Sensing handover method and corresponding sensing devices

FIELD OF THE INVENTION

The invention relates to the field of sensing of target objects or devices (which may or may not comprise a terminal device) by using fixed or mobile access devices in wireless networks, such as - but not limited to - fifth generation (5G) cellular communication systems. Although the invention will be described in the context of 5G networks, it would equally apply to other telecommunication systems, including cellular or based on a hybrid approach or ad hoc networks.

BACKGROUND OF THE INVENTION

As wireless communication systems such as 5G are foreseen to grow, there is an increasing need to be able to locate various nodes operating in the networks or to sense in real time their state. This applies in particular to mobile devices (e.g., user equipment (UEs)), which operate mostly as end terminals.

Thus, a useful asset for such networks can be augmented with wireless sensing capabilities to enable tracking or monitoring of targets as illustrated in Fig. 2. According to Fig. 2, a wireless access device 010, e.g., a base station or an access point, can perform wireless sensing in a sensing area Oil around the wireless access device 010. A target (device) 012, which may be a target device or an object (e.g., a car or a person) that may or may not be carrying or comprising a terminal device, is sensed or monitored or tracked or traced by means of different sensing technologies, e.g., radar measurements or channel state information (CSI) measurements, or Time of Flights of signals, or trilateration.

It is noted that the terms "sensing", "monitoring", "tracking" and "tracing" shall have the following meaning in this disclosure. Sensing or monitoring shall be understood as measuring or determining a (physical) parameter of a target (device) (e.g., the state of a target (device)) and can thus be used to enable tracking or tracing of the target (device) (e.g., tracking a state of the target (device) for a period of time). So-called 'mmWave' radar is a contactless sensing technology for detecting objects and providing range, velocity and angle of these objects and operates in a spectrum between 30GHz and 300GHz. Due to the technology's use of small wavelengths, it can provide submm range accuracy and is able to penetrate certain materials such as plastic, drywall, clothing, and is relatively impervious to environmental conditions such as rain, fog, dust and snow. The ability to sense surface positions and movements at sub-mm scale enables such systems to perform vital signs monitoring. As an example, signal wavebands of 5G communication systems or other suitable wireless communication systems can be used as mmWave radar e.g. to measure locations and movements of cars and people and even vital sign signals such as heart rate and breathing rate, but this requires knowledge of the transmission environment, approximate target location, and suitable modifications to the signaling system.

Fig. 3 shows a radar-based or CSI-based sensing system with a (distributed) wireless sensing solution in which a wireless sensing transmitter 013 and a wireless sending receiver 014 cooperate to sense a target 017. The wireless sensing transmitter 013 has a coverage area 015 and the wireless sensing receiver has a coverage area 016. The target 017 is monitored by means of a wireless sensing signal 018 whose wireless sensing signal reflection 019 is received by the wireless sensing receiver.

Wireless communication systems are distributed in the sense that there is a plurality of wireless access devices such as base stations or access points deployed in a region of interest (ROI), e.g., in a city or in a building. Thus, wireless sensing will require sensing of a target not only when the target is within the sensing range of a single wireless access device, but also within the overall ROI. An ROI can be defined as a location or area or volume in which a target is to be sensed/detected (i.e., a target location or area or volume) or in which the sensing is performed (i.e., a sensing location or area or volume).

SUMMARY OF THE INVENTION

It is an object of the invention to provide a sensing capability with wider range in wireless networks.

The above-mentioned object is achieved by a method as claimed in claim 1, a sensing apparatus as claimed in claim 15 and 16, an access device as claimed in claim 17, an access device or terminal device or network function as claimed in claim 18, a system as claimed in claim 19 and a computer program product as claimed in claim 20.

In accordance with a first aspect of the invention, a method of wirelessly sensing a state of a target using at least a first sensing device and a second sensing device is proposed, wherein the method comprises: determining whether a predetermined handover initiation condition is met, if the predetermined handover initiation condition is met, sending a first message to the second sensing device including at least a parameter related to the target, starting a service for the target by the second sensing device in response to a receipt of the first message. Thus, the first aspect of the invention enables the possibility of handing over the sensing (or tracking) of a target (device) to another sensing device. This allows maintaining the sensing or the tracking of the target (device) when the target (device) moves, for example out of coverage of the first sensing device. It is thus possible to keep the tracking, for example to maintain a real time tracking of the position or other state of the target (device), opening the door to other applications where the knowledge of such variable is essential. As an example, ultra-localized beam forming for improved communication capabilities would benefit from such real time tracking.

Therefore, a method of tracking a state of a target (device) including a handover process between a first sensing and communication device and a second sensing and communication device can be provided, wherein the handover process comprises the first sensing and communication device initiating a handover process once a predetermined handover initiation condition is met, the first sensing and communication device sending a first message to the second sensing and communication device including at least a parameter related to the target (device), and the second sensing and communication device starting a sensing or communication service with the target (device) subsequently to the reception of the first message.

The first sensing device may comprise a controller coupled to a sensor for sensing the state of the target (device), and a transceiver, the controller being configured for initiating the sensing handover process of the tracking of the target (device) to the second sensing device, wherein the controller is adapted to initiate the sensing handover process once the predetermined handover initiation condition is met, and wherein the transceiver is adapted to send the first message to the second device including at least a parameter related to the first target (device).

The second sensing device may comprise a controller coupled to a sensor for sensing the state of the target (device), and a transceiver being configured to receive the first message from the first sensing device including the parameter related to the target (device), wherein the controller causes the sensor to start sensing the target (device) subsequently to the reception of the first message.

The parameter related to the target may include at least one or more of the following: a spatial variable, absolute or relative location, absolute or relative speed, acceleration, orientation, direction of travel, travel direction variability, rotation rate, vibration rate such as a heart rate, or respiration rate, or a brain activity rate, health data of the user of the target, target pose, target gait, energy state of the target, power consumption of the target, or beam alignment. The value of one or more of these parameters related to the target (device) may be based on one or more monitored/tracked states of the target (device). The monitored state of the target (device) may include a spatial variable of the target (device), such as the location (absolute or relative), the speed (absolute or relative), the acceleration (absolute or relative), the altitude (absolute or relative), orientation, pose/gait information, shape/size information. The spatial variable may also include a travel direction or the change rate of such travel direction. Knowing a travel speed, direction or change rate of the travel direction helps to predict when to initiate the sensing handover and towards which other sensing device.

It is to be noted that, in some cases and exemplary embodiments, the target may include a device UE and the device may be involved in the sensing. In other examples and embodiments, the target may not carry a device UE and sensing may only be performed by, e.g., access devices. In the following description, unless explicitly expressed, the term "target" may be used to describe a target device including a communication device, such as a UE, or a simple target that does not include a communication device such as a UE.

The monitored state of the target (device) is not limited to the spatial variables (such as target location) and may consist of (or further comprise) other parameters such as health data of the target (e.g. heart rate, heart condition, blood pressure), energy state of the target (device) (e.g. remaining battery charge), power consumption of the target (device).

Another parameter that could become essential to enable ultra-high-rate communication is beam alignment, which for example correlates the current situation of the target (device) with the coverage by antenna beams (or lobes of transmitting antennas).

In a variant of the first aspect, the step of the second sensing device starting sensing the target (device) may include the transmission to and/or the reception from the first target (device) of a sensing signal/message. Indeed, as explained in further details in the following, the handover may be limited to the transmitting part of the sensing device or to the receiving part of the sensing device.

In another variant of the first aspect of the invention, the first sensing device may stop sensing the target (device) once a predetermined handover termination condition is met. More specifically, the handover termination condition may include at least one of the expiration of a timer e.g. a timer starting at the transmission of the first message, or a timer starting at the initiation of the handover, the first sensing device receiving an indication from the second sensing device or from the target (device) or from a network function in the core network that handover is completed, the first sensing device detecting that the second sensing device is sensing the first target (device), the target is detected to be at a distance relative to the first sensing device greater than a threshold, the quality of the sensing by the second sensing device is greater than a threshold, the quality of the sensing by the first sensing device is lower than a threshold.

In another variant of the first aspects, the handover initiation condition may include at least one of at least one of a sensed measurement on or of the target (device) meeting a threshold value, and a policy. More specifically, the sensed measurement meeting a threshold value may include at least one or more of: a parameter such as, e.g., signal strength, of the sensing signal is more or less than a threshold, the distance relative to the second sensing device is less than a threshold, the distance relative to the first target (device) is more than a threshold, a direction of travel of the target (device) is pointing towards the location of the second sensing device within an angular threshold, a direction of travel of the target (device) is pointing away from the location of the first sensing device within an angular threshold, the speed of the target (device) is higher than a speed threshold.

Thus, the handover can be initiated based on the quality of the sensing signal or the location of the target (device) relative to the first and/or second sensing devices, with for example some margins, to allow the handover to be completed before the target (device) is lost by the first sensing device. Such margins may be for example function of the speed of travel of the target (device) or other parameters. Some hysteresis margin may also be added to avoid back and forth handovers due to slight variations around the threshold value.

In addition or alternatively, the handover may be initiated based on a policy, which may include one or more elements, such as a periodic handover policy, i.e. handover is initiated if a sensing duration has expired. Other element may be based on the number of sensing devices currently sensing the target (device). For example, to maintain the accuracy of the target (device) tracking, a policy may aim at maintaining a sufficient number of sensing devices, e.g., forming a distributed array of sensing devices. If the number of sensing devices falls below a predefined number, handover may be initiated. A sensing device may be counted if the quality of the sensing is sufficiently high. Furthermore, if the strength of the sensing signal is below a given threshold, handover may be initiated.

In still another variant of the invention, a parameter related to the target (device) may include at least one of: a measurement report, a target (device) identifier, information regarding the estimated target (device) location, information regarding the target (device) type, information regarding the target (device) capabilities. Typically, the parameter transmitted in the first message may help the second sensing device to identify (or approximately locate) the target (device), in order to increase the speed of the handover.

In still another variant of the invention, the first and second sensing devices may be communication devices and the service may refer to a communication service for the target (device) by the second communication device.

In still another variant of the invention, the target (device) may monitor the handover initiation condition and sends the first message to the second sensing device.

In still another variant of the invention, the first sensing device may be formed by a first group of sensor apparatuses and/or the second sensing device may be formed by a second group of sensor apparatuses. Indeed, as mentioned earlier, the sensing devices may in fact be formed by multiple sensors or wireless nodes in a region, optionally organized with a master sensing device coordinating the other sensing devices in the group. Also, some of the sensor apparatuses of the first group may also be part of the second group of sensor apparatuses. Additionally, the group of sensor apparatuses may be formed in advance, based on their location in the vicinity of an area of interest.

All the previously detailed variants may be combined one with another and also apply to the following aspects of the invention.

In accordance with a second aspect of the invention, a sensing apparatus for wirelessly sensing a state of a target is proposed, the sensing apparatus being configured to initiate a handover process of the sensing of the target to a second sensing device in response to a determination that a predetermined handover initiation condition is met, and to send a first message including at least a parameter related to the first target to the second device.

In accordance with a third aspect of the invention, a sensing apparatus for wirelessly sensing a state of a target is proposed, the sensing apparatus being configured to receive a first message including a parameter related to the target from another sensing device, and to start sensing the target in response to a receipt of the first message

In accordance with a fourth aspect, it is proposed an access device comprising the sensing apparatus of the second aspect.

In accordance with a fifth aspect, it is proposed an access device or terminal device or network function comprising the sensing apparatus of the third aspect.

In accordance with a sixth aspect, it is proposed a system comprising an access device of the fourth aspect and an access device or terminal device or network function of the fifth aspect. In accordance with a seventh aspect of the invention, it is proposed a computer program product comprising instructions to cause, once loaded on a sensing device, the sensing device to perform the method of the first aspect of the invention.

In a further variant of the invention, a third sensing device may send the sensing request towards the second sensing device including identification information of the target.

In a still further variant of the invention, the third sensing device may combine the sensing information collected from the first and second sensing devices to sense the target over an overall area larger than the coverage area of either the first sensing device or the second sensing device.

In a still further variant of the invention, the third sensing device may interact with another device (e.g., NF/RAN in the 5GC) to get a configuration about the first and second sensing devices that can provide sensing results of a specific target in an area.

In a still further variant of the invention, the third sensing device interacts with another device (NF/RAN in the 5GC) to request the second device identity that can provide sensing results to sense a specific target.

In a still further variant of the invention, the third sensing device my interact with another device (e.g., NF/RAN in the 5GC) to request sensing results for a given area.

In a still further variant of the invention, the third sensing device may interact with an AF that requests the sensing of a given target.

It is noted that the above apparatus may be implemented based on discrete hardware circuitries with discrete hardware components, integrated chips, or arrangements of chip modules, or based on signal processing devices (e.g., mobile devices, access devices or other network devices or functions) or chips controlled by software routines or programs stored in memories, written on a computer readable media, or downloaded from a network, such as the Internet.

It shall be understood that the method of claim 1, the sensing apparatus of claim 15 and 16, the access device of claim 17, the access device or terminal device or network function of claim 18, the system of claim 19 and the computer program product of claim 20 may have similar and/or identical preferred embodiments, in particular, as defined in the dependent claims.

It shall further be understood that a preferred embodiment of the invention can also be any combination of the dependent claims or above embodiments with the respective independent claim.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following drawings: Fig. 1 schematically shows a distributed sensing function created via a 5G communication system link;

Fig. 2 schematically shows an architecture of a wireless network in which the invention can be implemented;

Fig. 3 schematically shows an architecture of a wireless network with distributed sensing capability in which the invention can be implemented;

Fig. 4 schematically shows an embodiment of a transmitter and receiver architecture, which may be used in embodiments of the present invention

Fig. 5 schematically shows an architecture of a wireless network with overlapping sensing structure in which the invention can be implemented;

Fig. 6 schematically shows a block diagram and an exchange of signals in accordance with a first embodiment of the invention;

Fig. 7 schematically shows a block diagram indicating how a handover is performed in accordance with the first embodiment of the invention;

Fig. 8 schematically shows a block diagram indicating how a handover is performed in accordance with a second embodiment of the invention;

Fig. 9 schematically represents a cell in which another embodiment of the invention is implemented;

Fig. 10 schematically represents sensing and sensing handover according to another embodiment of the invention;

Fig. 11 schematically represents sensing and sensing handover according to another embodiment of the invention;

Fig. 12 schematically represents a cooperative sensing procedure according to another embodiment of the invention; and

Fig. 13 schematically shows a block diagram and an exchange of signals for a cooperative sensing procedure according to another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention are now described based on a cellular communication network environment, such as 5G. However, the present invention may also be used in connection with other wireless technologies (e.g., IEEE 802.11/Wi-Fi or IEEE 802.15.4/ultra-wideband communication (UWB)) in which wireless sensing is provided or can be introduced.

Throughout the present disclosure, the abbreviation "gNB" (5G terminology) or "BS" (base station) is intended to mean a wireless access device such as a cellular base station or a WiFi access point or a UWB personal area network (PAN) coordinator. The gNB may consist of a centralized control plane unit (gNB-CU-CP), multiple centralized user plane units (gNB-CU-UPs) and/or multiple distributed units (gNB-DUs). The gNB is part of a radio access network (RAN), which provides an interface to functions in the core network (CN). The RAN is part of a wireless communication network. It implements a radio access technology (RAT). Conceptually, it resides between a communication device such as a mobile phone, a computer, or any remotely controlled machine and provides connection with its CN. The CN is the communication network's core part, which offers numerous services to customers who are interconnected via the RAN. More specifically, it directs communication streams over the communication network and possibly other networks.

Furthermore, the terms "base station" (BS) and "network" may be used as synonyms in this disclosure. This means for example that when it is written that the "network" performs a certain operation it may be performed by a CN function of a wireless communication network, or by one or more base stations that are part of such a wireless communication network, and vice versa. It can also mean that part of the functionality is performed by a CN function of the wireless communication network and part of the functionality by the base station.

Moreover, the terms "radar sensing" and "wireless sensing" are intended to cover not only techniques whereby a single device both sends and receives a radar signal, but also distributed RF based sensing techniques, such as techniques whereby the sensing signal is received by multiple devices in a distributed manner or techniques that are based on sensing of a channel state information (CSI) in a CSI-based distributed sensing solution and/or based on other types measurement information related to RF signals (e.g. MIMO sounding signal feedback, doppler phase shift measurements). The terms "radar sensing" and "wireless sensing" are used interchangeably in the description, and embodiments describing radar sensing as an example also extend to other types of wireless sensing, such as e.g. those using a reference signal so that UEs report relevant measurements of said reference signal, e.g., CSI-based sensing.

It is noted that throughout the present disclosure only those blocks, components and/or devices that are relevant for the proposed data distribution function are shown in the accompanying drawings. Other blocks have been omitted for reasons of brevity. Furthermore, blocks designated by same reference numbers are intended to have the same or at least a similar function, so that their function is not described again later.

SENSING SIGNALS The sensing function of the following embodiments may be implemented e.g. by a radar functionality in wireless communication involving one or more access devices (e.g., base stations (BS)) and/or one or more terminal devices (e.g., UEs).

As an example, Frequency Modulated Continuous Wave (FMCW) mmWave radar systems can measure range, velocity, and angle of arrival (if two receivers are available) of objects in the scene which reflect radio waves. Such radar systems emit a chirp signal, e.g., a sine wave that increases in frequency over time. The chirp signal (e.g., a continuous wave pulse) has a bandwidth and a frequency increase rate. Generally, a continuous series of such chirps are emitted. The transmitted and received analogue chirp signals are mixed to generate an intermediate frequency (IF) signal which corresponds to the difference in frequencies of the two signals (outbound and inbound) and whose output phase corresponds to the difference in the phases of the two signals.

Each surface of a scene or environment will therefore produce a constant frequency IF signal whose frequency relates to the distance to the surface (i.e., a first distance from the transmitter of the chirp signal to the surface plus a second distance from the surface to the receiver of the chirp signal). To resolve two surfaces at different distances, the two IF signals can be frequency resolved. A longer time window of the IF signal results in greater resolution. As the chirp time is related to its bandwidth (with constant chirp frequency change) the resolution of the radar is related to the chirp bandwidth. The IF signal may then be band pass filtered (to remove signals below some minimal range and frequencies above the maximum frequency for a subsequent analogue-to-digital converter (ADC)) and digitized prior to further processing. The upper frequency sensing range of the bandpass filter and ADC sets the maximum range that can be detected (i.e., IF frequencies increase with range).

To detect vibrations, the phase of the IF signal is important, since the phase (i.e., the difference in phases of the transmitted and received chirp signals) is a sensitive measure of small changes in the distance of a surface. Small distance changes can be detected in the phase signal but may be indiscernible in the frequency signal. Moreover, phase difference measures between two consecutive chirp signals can be used to determine the velocity of the surface.

As an example, a fast Fourier transform (FFT) processing can be performed across multiple chirp signals to enable separation of objects with the same range but moving at different velocities. A Fourier transform converts a signal from a space or time domain into the frequency domain. In the frequency domain the signal is represented by a weighted sum of sine and cosine waves. A discrete digital signal with N samples can be represented exactly by a sum of N waves. FFT provides a faster way of computing a discrete Fourier transform by using the symmetry and repetition of waves to combine samples and reuse partial results. This method can save a huge amount of processing time, especially with real-world signals that can have many thousands or even millions of samples. As a further example, angle estimation can be performed by using the phase difference between the received chirp signal at two separated receivers.

As another option, a channel state information (CSI) can be used, which is a measure of the phases and amplitudes of many frequencies detected at a receiver, thereby forming a complex 'map' of the radio environment, including effects of objects within that environment. CSI characterizes how wireless signals propagate from the transmitter to the receiver at certain carrier frequencies. CSI amplitude and phase are impacted by multi-path effects including amplitude attenuation and phase shift, e.g., by the displacements and movements of the transmitter, receiver, and surrounding objects and humans. In other words, CSI captures the wireless characteristics of the nearby environment. These characteristics, assisted by mathematical modeling or machine learning algorithms, can be used for different sensing applications.

A radio channel may be divided into multiple subcarriers, as is done e.g. in 5G communication systems (using e.g. orthogonal frequency division multiplexing (OFDM)). To measure CSI, the transmitter may send long training symbols (LTFs), which contain pre-defined symbols for each subcarrier, e.g., in a packet preamble. When those LTFs are received, the receiver can estimate a CSI matrix using the received signals and the original LTFs. For each subcarrier, the channel can be modeled by y = Hx + n, where y is the received signal, x is the transmitted signal, H is the CSI matrix, and n is the noise vector. The receiver estimates the CSI matrix H using a pre-defined signal x and the received signal y after signal processing such as removing cyclic prefix, de-mapping and demodulation. The estimated CSI is then a three-dimensional matrix of complex values and this matrix represents an 'image' of the radio environment at that time. By processing a time series of such 'images' information on movements, locations and vibrations of objects can be extracted.

Such a processing of a CSI matrix can be used for vital signs monitoring, presence detection, and human movement recognition. As an example, neural network like recognition techniques can be used to process the CSI matrix to perform such kinds of recognition.

It is noted that systems using channel state information (CSI) are somehow related to systems with FMCW mmWave radar. In a CSI-based system, the input signal X may be defined and the receiver may use the received signal Y to obtain H, i.e., as H = (Y - N) / X . In a FMCW mmWave radar, the transmitted signal Chirp X may also be predefined, and the receiver may uses the received signal Y to obtain a transfer function as H = Y / X . This last step is in fact somehow related to multiplying the locally computed chirp signal and the received chirp signal and applying a bandpass filter. According to various embodiments described below, the above described wireless sensing techniques are implemented in a mobile communication system (e.g. 5G or other cellular or WiFi communication systems), while the functional coexistence of radar and communication operating in the same frequency bands is configured to avoid interference bandwidths. Thereby, radio sensing can be integrated into large-scale mobile networks to create perceptive mobile networks.

As another example, the sensing signal may consist of a number of pulses sent, e.g., at specific frequencies and timing (sensing signal parameter information) by a sensing transmitter. The sensing receiver may include a number of bandpass filters that allow identifying the sensing signal parameter information, e.g, timing and frequency of the received pulses. In particular, if the transmitter determines a given pseudo-random sequence of frequency/timing pulses and beams it, e.g., by means of beamforming, in a specific direction, and if the transmitter communicates to the receiver the timing/frequency, in general, the sensing signal parameter information, of the transmitted sensing signal, the receiver can use its bandpass filters to identify the reception of the same transmitted pulses, i.e., sensing signal, based on the received sensing signal parameter information.

(DISTRIBUTED) SENSING CONFIGURATION AND OPERATION

Fig. 1 schematically shows a distributed radar function created via a wireless communication system link, which may be used in embodiments of the present invention.

However, it is to be noted that the present invention can be equally applied for nondistributed sensing services/function where a first sensing device performs sensing centrally and then (after handover) a second sensing device performs sensing centrally. Thus, the described embodiments can be implemented in a single device including both a transmitter and a receiver.

In a distributed radar function, in distinction to a purely centralized radar solution (i.e., whereby the transmitter and receiver of the radar signals are part of or operated by the same device), a part of the 5G (or other cellular or WiFi) network spectrum is configured (e.g., set into a radar mode) or is detected to be quiet/free of communication for a period of time to enable performing, e.g., remote vital signs and other measurements by construction of a distributed radar system between a base station (BS) 100 or UE (as transmitter) and at least oneUE 120 or base station (as receiver), while the lack of analogue signal exchange and the additional path length caused by the transmitter-receiver distance and the distance between the receiver (e.g., UE 120) and a target (e.g., human being) may be corrected for. To this end, a base station 100 (or UE) that will act as transmitter may set up a communication link with a UE 120 (or base station) that will act as a receiver (or vice versa) to exchange some control information and/or sensing measurements and/or (partial) sensing results. The control information may include a set of configuration parameters related to the distributed sensing operation. The parameters may include e.g., distance and angle from transmitter to receiver, pulse origination time, pulse phase, frequencies, possibly including chirp timing (CT), chirp profile (CP), target location (TL), phase offset (PO), time between subsequent sensing signals, number of repetitions, sensing signal waveform information, amplitudes, MIMO/beamforming parameters, number of transmitter antennas used, transmit power, potential interference patterns, an identifier/address (e.g., internet protocol (IP) address/uniform resource locator (URL) address) of a destination server and/or network function/device for sending the sensing results to (e.g., for storage or further processing), session or application related information (e.g., session identifier or application identifier), a desired accuracy for the sensing measurements, etc., and may be communicated in response (e.g., as a radio resource control (RRC) Connection Reconfiguration message including, e.g., a measurement configuration as specified in 3GPP TS 38.331 extended with sensing configuration parameters) to a request for radar (RR) (e.g., an initial Attach Request message from a UE to a base station or an RRC message or System Information as specified in 3GPP TS 38.331 from a base station to a UE, extended with a sensing request field) from the receiver side (e.g., UE 120), or may be sent to the receiver side by the transmitter side before the transmitter will start sending sensing signals (e.g., as part of a configuration/auxiliary information message/signal), or may be (partially) preconfigured on the receiver (e.g., stored in an universal subscriber identity module (USIM) or stored in a nonvolatile memory at manufacturing time), or may be configured on the receiver by means of a local application, or may be provided by the network (possibly via the transmitter or via another transmitter, or, e.g., provided by an access and mobility management function (AMF), policy control function (PCF), network exposure function (NEF), location management function (LMF), gateway mobile location center (GMLC), or other core network function (e.g., as specified in 3GPP TS 23.501)) as part of policy/system information/RRC configuration/session configuration (e.g., upon initial registration or connection setup of the receiver to the network or a previous initial registration/connection setup). These parameters may be configured differently per application (e.g., based on the sensing target or based on the sensing algorithm). A set of parameters may be combined in the form of a sensing profile that may be identifiable, e.g., by means of a profile identifier or application identifier or device identifier. After a sensing profile is sent/configured/pre-configured on a receiver, the activation of a sensing profile may be triggered by sending a signal/message to the receiver with an indicated sensing profile identifier. The sensing profile and/or the configuration parameters may also include an algorithm identifier, filter identifier or machine-learning model identifier to trigger the application of respectively a specific sensing algorithm, a filter or a machine learning model to use for analyzing/processing the received sensing signals. These algorithms, filters or models may be pre-configured/stored at the receiver beforehand, or transmitted by the transmitter to the receiver (e.g. as virtual machine code, filter parameters/code or model data), for example in a separate message, or may be downloaded (e.g., as virtual machine code, filter parameters/code or model data) by the receiver based on, e.g., a download URL or IP address of a server, may be configured for the application required. For example, if a precise distance measurement is required, the full set of parameters may be communicated, while if a phase-based velocity is required, only chirp parameters may be required. In some applications, the chirp parameters may be predefined and only an identifier indicating the set of chirp parameters may be exchanged. The parameters may also include a set of time/frequency resources (e.g., a semi-persistent schedule as defined in 3GPP TS 38.321) and/or time/frequency offsets in which the sensing signals are planned to be transmitted and/or when these are expected to arrive at the receiver. This information may also be provided as a time interval in which the receiver is expected to listen to incoming reflected sensing signals (e.g., as an offset to a start time or system frame number/subframe/symbol at which the signal will be transmitted by the transmitter). The start time, offset or time interval to perform the sensing by the receiver may be specified such that it starts at the start time or end time at which the first instance of the sensing signal is received by the receiver (i.e., the one received via a direct non-reflected path), i.e., reception of the first instance of the sensing signal can be used by the receiver to trig-ger/activate active sensing of the reflected sensing signals. The parameters may also include information about quiet periods or guard intervals that may be taken into account by the receiver device. In addition, the parameters may include information about encoded identity information or special symbol/preamble or a unique signal characteristic that can enable the receiver to uniquely identify the respective sensing signal from possible other sensing or communication signals. In order for the receiver to be capable of determining which parts of the sensing signal has encoded information in it (e.g., signal identity information, timestamp of when the transmitter sent the signal), additional timing or frequency information may be provided to identify start/end times or a subdivision of time intervals within the time interval for receiving a complete single sensing signal, that indicates where in the sensing signal the receiver can find the encoded information. In a similar way as for the sensing receiver, the sensing transmitter may be configured by the network (e.g., by an access and mobility management function (AMF), policy control function (PCF), network exposure function (NEF), location management function (LMF), gateway mobile location centre (GMLC), or other core network function (e.g., as specified in 3GPP TS 23.501)) as part of policy/system information/RRC configuration/session configuration (e.g., upon initial registration or connection setup of the sensing transmitter to the network or a previous initial registration/connection setup) with parameters on how to perform the sensing (e.g., pulse origination time, pulse phase, frequencies, possibly including chirp timing (CT), chirp profile (CP), target location (TL), phase offset (PO), time between subsequent sensing signals, sensing signal waveform information, amplitudes, MIMO/beamforming parameters, number of transmitter antennas to be used, transmit power, quiet periods or guard intervals that may be taken into account, etc.) and/or which algorithm, filter, sensing profile to use and/or which destination server and/or network function/device to send the sensing results to (e.g., for storage or further processing) and/or session or application related information (e.g., session identifier/application identifier), etc. The above-mentioned parameters for sensing may also be pre-configured on the transmitter (e.g., stored in USIM or stored in a nonvolatile memory at manufacturing time), or may be configured on the transmitter by means of a local application, or may be provided by the receiver.

In order to facilitate the configuration of the above mentioned sensing parameters, a sensing receiver or sensing transmitter device may provide its sensing related capabilities to the network (e.g., a core network function, or a service (operated/offered by the network) responsible for managing and/or performing the sensing (i.e., a sensing service), or an application function for managing and/or using the results of the sensing operations (i.e., a sensing application)), to one or more base stations, or to the other device(s) involved in the distributed sensing (e.g., to the sensing transmitter device in case of a sensing receiverdevice) by means of a capability exchange message (e.g., as part of the request for radar message, or an RRC UECapabilitylnformation message as specified in 3GPP TS 38.331, extended with some fields to denote the sensing related capabilities). The sensing related capability information may include for example device information (such as number of antennas or supported frequency ranges), wireless sensing signal processing capabilities (such as which algorithms supported, and/or whether it is capable of determining certain sensing results/goals (e.g., capable of determining a position or movement of a target object or a shape of a target object), one or more supported sensing profiles, etc.), wireless sensing signal transmission capabilities (whether this is supported and if so at which frequencies, etc.). The sensing receiver may be configured differently based on the received capabilities of the sensing receiver and/or sensing transmitter. The sensing transmitter may be configured differently and/or adapt the sensing signal based on the received capabilities of the sensing receiver and/or sensing transmitter.

The parameters to use for the configuration of the sensing transmitter and sensing receiver may depend on and be adapted based on sensing requirements that may be provided, e.g., through an application function or a network exposure function or other core network function/service or application, for example a sensing service or a sensing application. Such sensing requirements may, e.g., identify the type of sensing results that are expected to be calculated (e.g., movement, position, shape, material, biometrics), information about one or more target objects (e.g., information about rough location, last known location, identifiable features or already known features such as size or material or shape) and/or quality of service (e.g., desired accuracy, sampling rate) and/or information about algorithms/filters to be used and/or session/application related information (e.g., application identifier or session identifier). In Fig. 1, the base station (BS) 100 and/or the UE 120 determine(s) the (rough) location or area or volume of the target 150 by emitting a series of signals, e.g., chirp signals, that may be beamformed in the direction of the target 150. The (rough) location may also be in the form of a relative position, e.g., a set of distances and/or angles relative to a reference point (e.g., the transmitter or the receiver).

Optionally, e.g., before the actual radar sensing procedure is started between a transmitter and a receiver, the target angle and distance and/or target shape and/or target material/reflectivity characteristic may be determined using a location estimation radar operation and/or target shape determination operation and/or target material/reflectivity characteristic determination operation at the transmitter (e.g., base station (BS) 100), unless it is already known. This information may be stored at the transmitter and/or may be provided to the receiver and/or may be provided to a network function responsible for collecting the sensing measurements and/or (partial) sensing results and which may perform further processing on these sensing measurements/results to determine further sensing characteristics of a particular target.

Depending on the target sensing application, ahead of emitting a (chirp) signal, the precise timing of the phase and frequency (and optionally amplitude) of each individual (chirp) signal may be communicated (e.g., by using a protected standard communication signal) to the receiver (i.e., UE 120) optionally along with the location or relative position of the emitter (i.e., BS 100) and optionally rough location of the target 150. The idea of protected communication (encryption and/or integrity protection) is to make sure that only the target receiver can use this information. Based thereon, the receiver may optionally determine a path length and angle from the transmitter to the receiver and internally synthesize an analogue (chirp) signal matching the emitted (chirp) signal. Received and synthesized signals can be used for sensing purposes.

If the relative positions and exact times are known, the path length of reflected sensing signals via a target 150 can be determined and/or the target surface can be reconstruct-ed accurately, e.g., by detecting a correct intermediate frequency (IF) signal at a mixer output when the signal is a chirp signal. Knowing the rough position of the target object and/or by detecting the angle of arrival of the incoming reflected sensing signal(s), a distance or angle between the receiver and the target object and/or the emitter and the target object may be calculated. Knowing the phase and therefore phase difference, the velocity of the target 150 can be determined based on the frequency.

If only the velocity of the target 150 is required (as opposed to its position and velocity), the transmitter can optionally avoid providing its relative position and only communicate the phases, timing and frequency of emitted sensing signal. In certain cases, only the sensing signal itself may be transmitted to the receiver so that the receiver can use that sensing signal assuming a fixed time delay to compute the IF signal from which the velocity of the target can be derived. This may be of particular interest to measure vital signs such as breath or heart rate. For instance, it may allow to measure the speed of the breast when breathing and derive from it the breathing rhythm.

Given good enough reflecting surface location estimation, the receiver may ena-ble further data to be collected, such as skin conductivity.

In an example, the radar sensing capability can be achieved by the following procedures. The parameters of the sensing signals to be used in the transmitter sensing generation process, the rough location or relative position of the target and the position offset/angle from the transmitter to the receiver (e.g., UE 120), or the absolute/geographic location of the transmitter along with a future time or a set of time/frequency resources for first (and subsequent) sensing signals, are determined and communicated from the transmitter to the receiver by using, e.g., a protected communication signal.

Alternatively, some of the parameters may also be pre-configured at the receiver or may be configured at the receiver by means of a local application or may have been sent by the transmitter or the network at an earlier time (e.g., during a previous session). Then, the communicated parameter information is (optionally) decrypted and/or verified by the receiver. Thereafter, the transmitter emits sensing signals at the stated time by using, e.g., its discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) signal generation process to generate the sensing signal. The receiver may listen to the sensing signals at the time/resources as indicated in the parameter information. The receiver may use its DFT-s-OFDM signal generation process to generate an internal synthetic sensing signal (e.g., chirp) matching the parameters supplied, optionally with a delay corresponding to the direct distance from the transmitter to the receiver, thereby minimizing the IF frequency generated in the receiver. The receiver may use the supplied sensing parameter information and/or the internal representation of the sensing signals to configure its radio frequency (RF) reception frontend or signal detection unit to identify/detect the sensing signal amongst the signals received by the RF reception frontend. Upon detection and/or further processing of the received sensing signals, the receiver may determine and record/store start/end times, phase shifts, frequencies, amplitudes, signal deformations, signal strength, interference patterns, detected special symbols/preambles, encoded identity information of the sensing signals and/or timing of quiet periods between sensing signals. The receiver may use this information to further determine whether the received sensing signals are actually reflected by a target object or have been received via a direct non-reflected path between the transmitter and the receiver, in order to filter out only the relevant sensing signals to extract sensing information about a target object. To this end, the receiver may calculate the expected path loss and/or timing between transmitter and receiver for direct path, and expected path loss and/or timing via indirect reflected path via the target, and use this in the determination of whether the received sensing signals are actually reflected by a target object or have been received via a direct non-reflected path between the transmitter and the receiver.

Alternatively, the transmitter may calculate the expected path loss and/or timing between transmitter and receiver for direct path, and expected path loss and/or timing via indirect reflected path via the target, and send this information to the receiver, which can then use this in the determination. The receiver may form an IF signal using (e.g., mixing) the internal synthetic "emitted" sensing signal and the received sensing signal reflected at the target 150 and may perform band pass (or optionally only high pass filtering at the maximum frequency of the ADC) filtering and ADC to digitize the IF data and/or to digitize raw/filtered received reflected sensing signal data. To this end the receiver may create a compressed or uncompressed digitally sampled representation of the IF signal or the received raw/filtered reflected sensing signal(s), with a sampling frequency preconfigured at the receiver device, or a sampling frequency provided by the transmitter (e.g., as part of the sensing signal parameters). Also, information about which compression method/format to apply may be provided by the transmitter (e.g., as part of the sensing signal parameters) or preconfigured at the receiver. The digital IF signal may then be processed to yield application specific data (e.g., the output of one or more (pre-configured) algorithms or machine learning models), in this case sensing results related to the target (e.g. certain characteristics of the target such as its position, speed, shape, size, material composition etc. that may be determined after performing the respective signal processing/analysis on the received (reflected) sensing signals), or the digitized data from the receiver can be transmitted to the transmitter or a network function/device or a cloud to perform further application specific processing.

In addition to the processed or digitized data, the receiver may include identification information of the signal, sensing profile, algorithm/model, and/or the device, and may include timing and/or measurement information (e.g., arrival/end times, phase shifts, frequency, amplitude or signal deformations of the sensing signals) and/or antenna information/antenna sensitivity/MIMO configuration/beamforming configuration used by the receiver for sensing, and/or location/distance/angle related information of the receiver relative to the transmitter and/or the target, or as absolute coordinates, and/or information about the sensing application or sensing session (e.g., application identifier or session identifier).

A complete separation of transmitter and receiver in a digital radio system such as 5G implies that the receiver has no access to the analogue version of the directly emitted signal (phase, frequency), only the reflected sensing signal, and therefore cannot form the IF signal in the analogue domain. This would mean that all processing is performed on the received analogue signals (which requires a very fast ADC is to digitize the received "raw" sensing signal). Furthermore, in the proposed distributed radar sensing system, the distance to the reflecting surface of the target 150 depends on both the distances from the transmitter to the target 150 and from the receiver to the target 150 (rather than simply being twice the distance from the transmitter to the target, as in non-distributed radar systems).

The "minimum range" of the measurement corresponds to the direct distance from the transmitter to the receiver. Of course, objects may be measured which lie at smaller distances from the receiver, but their indicated range will always be greater than the direct distance from the transmitter to the receiver. Equal time returns lie on spatial position ellipses (return ellipses) having the transmitter and receiver positions as their two focal points. The minimum (degenerate) ellipse with a short axis length of zero (a straight line between transmitter and receiver) has a minimum delay time, which is the time taken for radio waves to go directly from transmitter to receiver.

The receiver may receive a signal corresponding to the directly transmitted signal straight from the transmitter to the receiver (a pseudo-surface at "zero" range, i.e., points on the direct line between transmitter and receiver).

Therefore, the proposed integrated distributed radar system may require a kind of clock-level synchronization between transmitter and receiver to remove ambiguity in sensing parameter estimation.

Furthermore, the auxiliary information signals (e.g., radar request and respond-ed parameters) can be communicated between the transmitter to the receiver via an alternative communication route (using, e.g., a separate band, a beam formed sub-beam directed at the receiver, or time interspersed signals between sensing signals) so that the receiver can obtain a representation of required details of the transmitted signal (e.g., precise timing, phase of the continuous (chirp) signal) in order to simulate the mixing of the transmitted and received signals to obtain an IF signal without requiring direct analysis of the analogue emitted signal. This could be done by, for example, internally generating an analogue version of the identical emitted sensing signal using the parameters supplied via the auxiliary information signal. Thus, to ensure that a correct timing is provided for this mixing of a simulated transmitter sensing signal and the actual received sensing signal, the transmitter should signal the precise timing, phase, frequencies etc. of the emitted signal to the receiver ahead of time.

Furthermore, the receiver may use the auxiliary/(pre-)configured information/parameters about the sensing signal to distinguish between a sensing signal received via a direct non-reflected path, versus reflected sensing signals. The receiver may ignore the sensing signals received via a direct non-reflected path (e.g., by ignoring the first instance of receiving the sensing signal (for example, by checking the arrival time of the sensing signal, or by checking for phase shifts, frequency changes, signal deformations, amplitude changes, interference patterns that correspond to identify which of the sensing signals has been reflected or not), or may use these signals to more accurately determine its relative position/distance/angle towards the transmitter. The receiver may also use the signal received via a direct non-reflected path as further input to the signal analysis algorithm/model, e.g., as additional reference signal for IF calculation, (relative) position calculation or additional phase shift/signal deformation/frequency/amplitude calculations.

Additionally, the distance and angle from the transmitter to the receiver or the absolute/geographical position of the transmitter may be signaled as well, in order to calculate the correct positions for detected surfaces.

Finally, if the receiver (or transmitter, or both) is a hand-held device, the move-ments and vibrations of that device(s) may be measured by corresponding sensors, in order to subtract them from the movements and vibrations of the detected surfaces for some sensing applications.

The proposed distributed radar system between, e.g., the base station (BS) 100 (as the transmitter) and the UE 120 (as the receiver and analyzer) provide the advantage that the receiver may be located more preferentially for obtaining the reflected sensing signals at higher signal strength than the transmitter (i.e., using the receiver part of the transmitter device to monitor the reflected sensing signals, e.g., as in the case of non-distributed sensing), for example it may be closer or more in the path of the reflected sensing signal, and may avoid some of the clutter from the transmitted signal.

Moreover, a single antenna may not operate in full continuous duplex mode, while the proposed distributed radar system separates the transmitter antenna from the receiver antenna.

As a further advantage, multiple receivers can be used with a single transmitter, each possibly associated with collecting vital signs from a different target (e.g., individual human being).

However, as explained above, the sensing may be performed centrally by a single first device and, after sensing handover, the sensing may again be performed centrally by a single second device.

SENSING TRANSMITTER AND RECEIVER ARCHITECTURE

Fig. 4 schematically shows an embodiment of a summarizing transmitter and receiver architecture (including optional elements and functions) of a communication system with distributed sensing capability.

Although the architecture shows the transmitter device and receiver device as distinct devices in a distributed sensing system, the functions of the sensing transmitter and sensing receiver may be co-located in the same device (e.g. in case of a centralized sensing architecture), whereby (a subset of) similar functions and elements are expected to be present. The proposed distributed radio wave sensing radar/communication system comprises a transmitter device (TX) 10 and a receiver device (RX) 20 and is configured to operate over a suitable radio frequency range (such as the initially mentioned mmWave range) and comprises RF hardware and signal processing algorithms to enable both standard communication, e.g., 5G, and radar sensing for vital signs, object detection and/or movement recognition. In 5G systems, two options for an uplink (UL) waveform are provided. One is cyclic prefix OFDM (CP- OFDM, same as downlink (DL) waveform) and the other one is discrete Fourier transform spread OFDM (DFT-s-OFDM) which corresponds to the UL waveform in long term evolution (LTE) systems (i.e., fourth generation (4G)). Transform precoding is the first step to create the DFT-s-OFDM waveform, followed by sub-carrier mapping, inverse FFT and cyclic prefix (CP) insertion. Whether a UE needs to use CP-OFDM or DFT-s-OFDM can be determined by a radio resource control (RRC) parameter.

A 5G transmitter or receiver with integrated radar sensing capability may have slightly modified DFT-s-OFDM and frequency domain spectral shaping (FDSS) filters enabling them to generate suitable chirps. Linear and other chirp signals can be generated with DFT-s-OFDM signals via a well-designed FDSS filter enabling standard communication hardware with only minor modification to generate suitable signals for radar. Their framework offers a way to efficiently synthesize chirps that can be used in dual-function radar and communication (DFRC) or wireless sensing applications with existing DFT-s-OFDM transceivers.

Other options for generating a signal suitable for simultaneously performing data transmission and radar sensing are described in Cong Li et al.: "Radar Communication Integrated Waveform Design Based on OFDM and Circular Shift Seguence", Mathematical Problems in Engineering, July 2017, and are based on a peak-to-mean envelope power ratio (PMERP) and a peak-to-side-lobe ratio (PSLR) of OFDM waveforms. To be specific, a Gray code technology can be adopted to reduce the PMERP and simultaneously choose an optimal cyclic sequence to improve the PSLR of an OFDM waveform. The optimal cyclic sequence is dynamically generated to continuously provide the best waveform according to the change of communication data. In addition, to meet the requirements of different radar detection tasks, two simple methods can be utilized to adjust the bandwidth of the OFDM waveform. One method is to design different subcarrier complex weights and the other method is to utilize a phase code technique.

The transmitter device (TX) 10 may be an access device (e.g., base station) or a terminal device (e.g., UE or internet of things (loT) device) and comprises a standard transmitter communication unit or system (S-TX-COM) 101 enabling standard communication, e.g., 5G, capabilities using, e.g., DFT-s-OFDM generated data communication signals. By operating in a "radar mode", the transmitter communication system 101 is capable of forming a radar mode signal generator (RM-SIG-GEN) 102 capable of, e.g., generating linear chirp signals (chirps) using minimally modified communication components. This can be achieved, e.g., by a using (slightly) modified DFT- s-OFDM with a suitable FDSS filter for converting the single-carrier nature of the DFT-s-OFDM signal to a linear combination of chirp signals circularly translated in the time domain, as described, e.g., in Alphan §ahin et al.: " DFT-spread-OFDM Based Chirp Transmission”, IEEE Communications Letters, Volume: 25, Issue: 3, March 2021. By exploiting properties of Fourier series and Bessel function of the first kind, an FDSS filter for an arbitrary chirp can be obtained.

Furthermore, the transmitter device 10 comprises a transmission frontend (TX/ANT) 103 (e.g., capable of operating in mmWave frequencies) including a transmitter coupled to antenna with beam forming capabilities.

Optionally, a reception frontend (RX/ANT) 104 (e.g., capable of operating in mmWave frequencies) may be provided (e.g., as a separate component or integrated with the transmission frontend 103 in a joint transceiver frontend), which includes a receiver coupled to an antenna with beam forming reception capabilities (e.g., if an additional non-distributed transmitter- only radar operation is to be performed to determine a target location, shape/size or material/reflectivity characteristic).

Additionally, the transmitter device 10 comprises a transmitter clock generator (TX- CLK) 105 for generating an accurate system clock for the transmitter device 10.

Optionally, a transmitter time delay measurement functionality (not shown) may be provided (e.g., implemented by a processor/controller of the transmitter device 10), which uses the standard transmitter communication unit 101 to perform a two-way time delay measurement with a cooperative receiver device (e.g., the receiver device 20).

Optionally, an encryption and decryption functionality (ENCR/DECR) 106 may be provided for implementing a suitable data encryption/decryption scheme (based on, e.g., the Advanced Encryption Standard (AES) algorithm or the Rivest, Shamir and Adleman (RSA) algorithm) and data integrity verification (e.g., a data verification scheme using a message authentication code or digital signatures). For instance, data may be distributed in a protected radio resource control (RRC) message.

As a further option, the transmitter device 10 may comprise a non-distributed (low- resolution) transmitter radar analysis system (L-RES RAS) 107, i.e., a radar analysis system that may comprises a receiver device and/or may comprise a (low-resolution) transmitter radar analysis system, which provides a non-distributed location radar scanning capability, which may include an intermediate frequency (IF) generation mixer (IF-MIX) 107-1 to which a copy of an emitted sensing signal and an externally received reflected sensing signal are supplied and mixed to generate a mixed signal including an IF signal. Furthermore, the transmitter radar analysis system 107 may comprise electronic signal processing components - including a transmitter band pass filter (BPF) 107-2 and an analog-to-digital converter (ADC) 107-3 - capable of IF filtering and analogue to digital conversion of the generated IF signal. Moreover, the transmitter radar analysis system 107 may comprise a digital signal processing component and algorithm system (DSP, implemented by, e.g., a digital signal processor) 107-4 which provide DSP capabilities for, e.g., location detection, preprocessing by clutter removal, etc.

As a still further option, the transmitter device 10 may comprise sensor components including transmitter movements sensors (TX-MOV-SEN) 108, such as accelerometers or the like, which measure movements and vibrations of the transmitter device 10.

Furthermore, the receiver device 20 may be an access device (e.g., base station) or a terminal device (e.g., UE or Internet of Things (loT) device) and may comprise a standard receiver communication unit or system (S-RX-COM) 201 that provides standard communication capabilities, e.g., in 5G, using, e.g., DFT-s-OFDM-generated data communication signals. By operating in a "radar mode", the receiver communication system 201 may be capable of forming a radar mode signal generator (RM-SIG-GEN) 202 that, e.g., generates linear sensing signals, e.g., by using a (slightly) modified DFT-s-OFDM signal, wherein the generated sensing signals may be used internally and not coupled to a transmitter and antenna. The waveform of the sensing signal may be generated from specific input parameters that may include at least one of a specific start time, a phase, an amplitude, a base frequency, a band width, a frequency slope, a sensing signal repetition frequency, a gap between sensing signals, and a total number of sensing signals.

Furthermore, the receiver device 20 comprises a reception frontend (RX/ANT) 204 which includes a receiver coupled to a antenna with beam forming reception capabilities, and which may be capable of operating in mmWave frequencies.

Additionally, the receiver device 20 comprises a receiver clock generator (RX-CLK) 205 for generating an accurate system clock for the receiver device 20.

Optionally, a receiver time delay measurement functionality (not shown) may be provided (e.g., implemented by a processor/controller of the receiver device 20), which uses the standard receiver communication unit 201 to perform a two-way time delay measurement with a cooperative transmitter device (e.g., the transmitter device 10).

Optionally, an encryption and decryption functionality (ENCR/DECR) 206 may be provided for implementing a suitable data encryption/decryption scheme (based on, e.g., the Advanced Encryption Standard (AES) algorithm or the Rivest, Shamir and Adleman (RSA) algorithm) and data integrity verification (e.g., a data verification scheme using a message authentication code or digital signatures) matched to the scheme(s) used on the transmitter side. For instance, data may be distributed in a protected radio resource control (RRC) message.

As a further option, the receiver device 20 may comprise a (low-resolution) nondistributed radar analysis system (L-RES RAS) 207 which provides a non-distributed location radar scanning capability, i.e., a radar analysis system that may comprise a receiver device and/or may comprise a (low-resolution) transmitter radar analysis system, which may include a transmitter frontend (TX/ANT) 203 including a transmitter coupled to an antenna with beam forming capabilities of the receiver device 20.

Additionally, the (low-resolution) radar analysis system 207 may include components which are shared with an additional high-resolution distributed radar analysis system (H-RES RAS) 209 and which may comprise an IF generation mixer (IF-MIX) 207-1, to which a (internally generated) copy of an emitted sensing signal and an externally received reflected sensing signal are input to generate a mixed signal including an IF signal, electronic signal processing components including a receiver band pass filter (BPF) 207-2 and an ADC 207-3 and capable of IF filtering and analogue to digital conversion of the generated IF signal, and an electronic and digital components and algorithm system (DSP, e.g., a digital signal processor) 207-4 which provide DSP capabilities for, e.g., location detection, preprocessing by clutter removal, etc.

The high-resolution distributed radar analysis system 209 may be configured to share electronics components of the IF generation mixer 207-1, which is configured to mix the inputs of an internally generated sensing signal based on supplied timing/phase parameters produced by the radar mode signal generator 202 and an externally received sensing signal supplied by the receiver frontend 204, electronic components of the receiver band pass filter 207-2 and ADC 207-3, which take an analogue IF signal, filter it with a suitable bandpass filter and perform analogue to digital conversion, and the electronic and digital components and algorithm system 207-4, which provides DSP capabilities for desired applications, including pre-processing by clutter removal etc. In order to prevent leakage/tampering of potentially privacy sensitive sensing information about a target, the radar analysis should run in a secure tamper-resistant subsystem, and the resulting sensing information should be stored on a secure storage and/or encrypted with non-tamper resistant credentials (such as subscriber identity module (e.g., USIM) credentials)

Alternatively, a final digital processing could be off-loaded from the receiver device 20 to the transmitter device 10 or to a network function/device or a cloud computing resource, which may return obtained results. Optionally, the receiver device 20 may comprise a user Interface (UI/MEM) 210 with data storage and display capabilities, which can input information from a user, store data in the receiver device 20 and output displays to the user. Specific elements of the user interface 210 may be dependent on the type of receiver device (e.g., UE) and its function. For example, a handheld smartphone device may have a sophisticated user interface 210 and display, while an loT monitoring device may simply have a visual or auditory alarm.

As a further option, the receiver device 20 may comprise receiver movements sensors (RX-MOV-SEN) 208 such as accelerometers, cameras, structured light sensors, etc., which measure movements and vibrations of the receiver device 20, and locations of nearby objects. The receiver device 20 may also communicate via its transmitter standard communication unit 201 to the transmitter device 10 its movements and vibrations by using a receiver movement data series during a sensing time interval, which have been obtained by the receiver movements sensors 208. The receiver movement data series may be sent to the transmitter by using a separate communication channel between the receiver and transmitter (e.g., as a series of RRC or media access control (MAC) control element (CE) messages).

SYSTEM ELEMENTS

Fig. 5 schematically shows an architecture of a wireless network with overlapping sensing structure in which the invention can be implemented.

As explained above, wireless sensing may require that a single wireless device is capable of sensing a target when the target is within the sensing range of the single wireless device, and may require means to allow multiple wireless access devices to work together to sense a target in the overall ROL This is illustrated by means of Fig. 5 which shows an ROI in the form of a hexagon 024. The target 021 can move anywhere in the ROI. Multiple wireless sensing devices with overlapping sensing areas are used for sensing/tracking/monitoring the target, each of those wireless sensing devices with a sensing area smaller than the ROI. For instance, wireless sensing device 022 has a sensing area 023. The system elements relative to the various embodiments of the invention are now described with reference to Fig. 6.

Fig. 6 schematically shows a block diagram and an exchange of signals in accordance with a first embodiment of the invention. Each signal exchange between involved system components is indicated as an arrow which starts resp. ends below the respective signaling components, while the time proceeds from the top to the bottom of Fig. 6. More specifically, the entities involved in the system and the types of sensing and cooperative sensing procedures disclosed in various embodiments of the invention are schematically described.

The following entities may be included:

• A (mobile) target (T) that may be a person, a car, an unmanned aerial vehicle (UAV), etc. requiring tracking, monitoring, or sensing services. A target device may be a UE (such as a mobile communication device) included in the target or used by the target. For instance, the target may be a car or a UAV and may include a target device/UE; such a target may require wireless sensing service to, e.g., better estimate its position. For instance, a target may be a person without a UE; such a target may have subscribed to a sensing service to keep track of his location as well as other parameters, e.g., health data monitoring such as heart and breathing rate. Other applications in other fields than health are also possible, for e.g. automotive, freight (e.g. by car, drone). More general, the terms "target" and "target object" indicate any entity that may be subject to wireless sensing. This may include people, animals, inanimate objects, structures consisting of several smaller entities (e.g. a cloud consisting of small waterdrops)). Also, the terms "target" and "target object" may be used as synonyms in this disclosure.

• S_Rxl refers to at least a first sensing receiver at a first location.

• S_Rx2 refers to at least a second sensing receiver at a second location.

• S_Txl refers to at least a first sensing transmitter at a first location.

• S_Tx2 refers to at least a second sensing transmitter at a second location.

• S_Rxl and S_Txl (S_Rx2 and S_Tx2) may be co-located at a first (second) location and may be implemented individually or jointly by means of a base station or a distributed unit of a base station, or an access point or a UE or a reflective intelligent surface (RIS) or a smart repeater. In some situations, only the receiver S_Rxi or the transmitter S_Txj are used for the sensing application.

• AMF refers to the 5G Core Access and Mobility Management function in charge managing registrations, reachability, connections, or mobility.

• SF refers to a sensing function in the core network in charge of managing sensing functionality of a given target.

• NEF refers to the network exposure function in the 3GPP 5G Architecture. This function provides a means to securely expose the services and capabilities provided by 3GPP network functions.

• AF refers to an (external) application function.

Throughout the present disclosure, the terms 'sensing' and 'monitoring' are used interchangeably. 1

OVERVIEW OF SENSING AND HANDOVER PROCEDURES

As shown on Fig. 6, centralized and distributed sensing paradigms may include:

• 031 (centralized): the first sensing transmitter sends a sensing signal 0311 and the first sensing receiver obtains sensing signal 0312 from the target.

• 032 (distributed): the first sensing transmitter sends a sensing signal 0321 and the second sensing receiver obtains sensing signal 0322 from the target.

A sensing signal may be based on multiple technologies. For instance, radar based where the sensing signal refers to the radar signal reflected on the target (device) and sensed by a sensing receiver, e.g., not co-located with the target (device). Or for instance based on a given reference signal where the sensing signal refers to measurements performed by a sensing receiver, e.g., at the target (device).

Furthermore, proposed types of cooperative handover procedures covered by handover mechanisms described in the following embodiments and illustrated in Fig. 6 include:

• 033 (sensing transmitter handover): the target is monitored first by the first sensing receiver by monitoring sensing signal 0332 obtained after reflection/measurements of sensing signal 0331 distributed by a first sensing transmitter. The first sensing receiver keeps sensing the sensing signal 0332 while performing a sensing handover towards the second sensing transmitter that starts providing support for the monitoring (i.e., by a sensing receiver) of the target by sending sensing signal 0333 that is received by the first sensing receiver as 0334.

• 034 (sensing receiver handover): the target is monitored first by the first sensing receiver by monitoring sensing signal 0342 obtained after reflection/measurements of sensing signal 0341 distributed by a first sensing transmitter. The first sensing receiver keeps sensing the sensing signal 0341 while the first sensing transmitter or the first sensing receiver itself performs a sensing handover towards the second sensing receiver that starts monitoring the target by measuring signal 0344.

• 035 (sensing handover): the target is monitored by carrying out a sensing handover from the first sensing receiver/transmitter (sending/receiving sensing signals 0351 and 0352) to the second sensing receiver/transmitter (sending/receiving sensing signals 0353 and 0354).

Proposed types of cooperative sensing procedures covered by the handover mechanisms described in the following embodiments and illustrated in Fig. 6 include:

• 031 + 032 (joint sensing with multiple receivers and transmitters): the first sensing transmitter sends a sensing signal 0311 and the first sensing receiver obtains sensing signal 0312 from the target. Simultaneously, the second sensing transmitter sends a sensing signal 0321 and the second sensing receiver obtains sensing signal 0322 from the target. The first and second sensing receivers combine the sensing signals, e.g., at the SF or the centralized unit of a base station or at a DU of a base station, to obtain a better sensed signal. Note that the transmitted sensing signals 0311 and 0321 may be different or related, e.g., may be the same sensing signal only differing a given phase.

• 036 (joint sensing with a single transmitter and multiple receivers): the first sensing transmitter sends a sensing signal 0361. The target (UE) reflects or transmits a sensing signal that is received by at least two receivers in signals/messages 0362 and 0363. The first and second sensing receivers combine the sensing signals, e.g., at the SF or the centralized unit of a base station or at a DU of a base station, to obtain a better sensed signal

• 037 (joint sensing with multiple transmitters and a single receiver): multiple sensing transmitter send sensing signals, i.e. the first sensing transmitter sends a sensing signal 0371 and a second sensing transmitter sends a sensing signal 0372. The target reflects or transmits a sensing signal that is received by a sensing receiver in signals/messages 0373.

SENSING HANDOVER PROCEDURE: OPERATION OF SENSING DEVICES

A first general embodiment is described with reference in Fig. 7. Fig. 7 schematically indicates a sensing mobility procedure corresponding, e.g., to 035 in Fig. 6. This sensing mobility procedure can be required in use cases where the sensing infrastructure is distributed, e.g., implemented by multiple sensing devices, e.g., 0401 and 0402 in Fig. 7, each device with a given sensing range or area. The first sensing device 0401 may include a first sensing receiver S_Rxl and a first sensing transmitter S_Txl. The second sensing device 0402 may include a second sensing receiver S_Rx2 and a second sensing transmitter S_Tx2. The sensing infrastructure covers an overall area (ROI), usually larger than the sensing area of a single sensing device as shown in Fig 5. The sensing devices 0401 and 0402 need to coordinate to sense targets that move through the overall sensing area. For instance, such a sensing infrastructure may be based on base stations in charge of keeping track of and sense cars, UAVs, people, etc.

In Fig. 7, the first sensing device 0401 and the second sensing device 0402 cooperate to keep track of a target 0400 moving from a first target location 0403 towards a second target location 0404. In this mobility procedure, the first and second sensing devices 0401 and 0402 have a limited sensing range and it is desired to keep track of the moving target 0400, e.g., a car, a UAV, a person, etc. The first and second sensing devices 0401 and 0402 may use multiple sensing technologies as described above. For instance, the first sensing device 0401 may send a sensing signal 0405 towards the target 0400 at the first target location 0403 and receive a message/signal 0406 that may be, e.g., (i) a message containing a set of CSI measurements collected by the target 0400 at the first location 0403 and/or (ii) a reflected component of the (radar) sensing signal 0405. In either case, the message/signal 0406 allows the first sensing device 0401 to determine certain aspects (such as position, speed, acceleration, beam alignment, heart rate, etc) of the target 0400 at the first location 0403. The first sensing device 0401 may determine that the target 0400 is moving away from its sensing area by monitoring certain aspects (e.g., signal strength, frequency shift, or measurements carried out by the target and included in the received signal 0406). If this event happens, the first sensing device 0401 informs the second sensing device 0402 of the approaching target 0400. Indeed, the first sensing device can look up in a list of neighboring sensing devices which one(s) is (are) most likely to become the sensing devices closest to the target (device) 0400 and initiate a handover on this basis.

The first sensing device 0401 may know which sensing device to inform based on, e.g., the second procedure described below in the context of Fig. 8, or a predetermined map of the sensing devices, or based on other embodiments in this application. Then, the first sensing device 0401 informs the second sensing device 0402 by sending a message 0407 to the second sensing device 0402, e.g., a base station, e.g., through a communication interface, e.g., the Xn interface, with the identity of the target 0400 and/or its current location (e.g., the first location 0403) and/or other parameter related to the target (e.g. a monitored state of the target). Note that the second sensing device 0402 may also be a UE and in this case the messages may be, e.g., RRC messages exchanged over the Uu interface. Note that the first and the second sensing devices may also both be UEs and in this case the messages may be exchanged over the PC5 interface. The first sensing device 0401 can know which sensing device to inform, e.g., if the sensing devices know the location or the sensing area of surrounding sensing devices. Note, that the first sensing device 0401 may also inform other sensing devices, e.g., proactively or based on a policy. The second sensing device 0402, upon reception of message 0407 may proceed to send (a) sensing signal(s) 0409. The second sensing device 0402 may also monitor whether it detects the sensing signal 0408 coming from the first sensing device 0401 reflected at the target 0400 at location 0403. The second sensing device 0402 may discern whether this signal 0408 comes from the target 0400 if the first sensing device 0401 uses a specific sensing signal, e.g., including an identifier identifying the sensing signal or using any signal that may be identifiable at least within the area, e.g., using a very specific radar signals, e.g., a very specific chirp timing/frequency. This identity of the sensing signal (and/or signal characteristics of the sensing signal and/or other information relevant for sensing, such as sensing measurements received thus far, sensing results, predicted/estimated trajectory/speed/direction of the intended target, target application ID/URL, identity of core network functions (e.g. sensing service) involved, identity or location of the first sensing device, information about surrounding sensor/receiver devices that may be involved in the measurements (e.g. their location), synchronization information, a set of target identification information (e.g. matching criteria for a target), or a sensing session identifier) from the first sensing device 0401 may be communicated to the second sensing device 0402 in message 0407. Note that the location of a target and of the first sensing device may be specified as an absolute position (e.g. geographical coordinates) or relative position (e.g. distance/angle from the receiver or other reference device or reference coordinate) or as an area/volume (e.g. an area/volume in which the target is expected to reside or in which it appears to be with minor fluctuations, e.g. due to measurement errors or signal variations), possibly formatted as a set of Universal Geographical Area Description (GAD) shapes (as specified in 3GPP TS 23.032). Upon reception of the signal 0408, the second sensing device 0402 may start transmitting its own sensing signal 0409 that may also be identifiable, e.g., by embedding an identifier or any other means. The second sensing device 0402 then receives a signal 0410, e.g., a reflected component of the sensing signal 0409 or any other information, that allows the second sensing device 0402 to sense/monitor/keep track of the target 0400. The second sensing device 0402 may use the information (i.e., parameters) that it has received (from the first sensing device 0401) about the target (e.g. the latest value of a monitored state of target 0400, or a set of target identification information) to identify target 0400 in its sensing data and/or verify if a detected object matches the target 0400 (e.g., by verifying if the sensing results correspond to the received information about the target within a (pre-)configured margin of error). Since the sensing measurements of target 0400 by the second sensing device 0402 may be initiated after a certain delay, the first sensing device 0401 may include a timestamp in the message or in the information inside the message about target 0400 (e.g., an absolute or relative time at which the value of a monitored state was determined before it was transmitted to the second sensing device 0402). The second sensing device 0402 may calculate the delay between such timestamp (or the time at which it received the message if no timestamp is included) and the time it initiated sensing of target 0400 or time it calculates (or has calculated) the first sensing results about target 0400. This delay may be used to compensate for the transitions/differences that may have occurred during that time in the sensing of target 0400. For example, if the target was moving at a certain speed in a certain direction, the location of the target 0400 determined by the second sensing device 0402 can be expected to be shifted. The second sensing device 0402 may estimate/predict (e.g., through extrapolation) a new position of the target or a value of a monitored state of the target by using the time delay, and may use the expected difference in position or state in the identification, matching or verification of target 0400 using the information received about the target 0400 from the first sensing device 0401. Alternatively or additionally, the time delay may be used to estimate/predict a new position of a target 0400 and use this new position for beamforming to the target 0400. At this point, the second sensing device 0402 may communicate to the first sensing device 0401 by means of message 0412 that it has sensed the target 0400, e.g., at the second target location 0404. The message may include the identity of the sensing signal 0409 used by the second sensing device 0402 as well as information regarding the sensing quality. Sensing quality may refer to, e.g., location accuracy, speed accuracy, target frequency (e.g., breathing, heart rate, in the case of a person), signal strength of the received signal, etc. The first sensing device 0401 may measure at this point a sensing signal 0411 coming from the second sensing device (e.g., a component of the sensing signal 0409 reflected at the target 0400 at the second location 0404 or a set of measurements by the target 0400 on signal 0409 that are sent to 0401). The first sensing device 0401 may release the tracking of the target 0400 and inform the second sensing device 0402 by means of a message 0413 that it is stopping the tracking. Alternatively, the first sensing device 0401 may stop tracking after sending message 0407. In particular, the first sensing device 0401 may stop tracking once it has sensed/received signal/message 0411. Alternatively, the first sensing device 0401 may have included already in message 0407 the condition for releasing the sensing, e.g., when the second sensing device 0402 achieves a given sensing quality on the target, or a time when the first sensing device 0401 will stop sensing of the target. When the second sensing device 0402 achieves this target sensing quality or other condition is fulfilled (e.g., a timer expiring), or when the second sensing device 0402 has initiated transmission of sensing signals or when the second sensing device 0402 has successfully received signal 0410, signal 0408 or message 0407, the second sensing device 0402 may inform the first sensing device 0401 about this in message 0412. In this case, the first sensing device 0401 may not be required to send message 0413. Note that the first and second sensing devices 0401 and 0402 may make use of distributed localization methods to determine the position of the target 0400 more accurately by using the reflected sensing signals 0408 and 0411. E.g., by measuring the sensing signal at two receiver devices to obtain a first equal-distance return ellipse (range ellipse) for the first receiver device and a second equal-distance return ellipse (range ellipse) for the second receiver device. The two range ellipses provide two intersection points, wherein one of the intersection points is selected as target location, if it is located in the beam forming direction and beam spread of the transmitted sensing signal. Alternatively, an equal-distance return ellipse (range ellipse) may be obtained for a first receiver device and an equal-distance return circle (range circle) may be obtained for a combined transmitter/receiver device. Again, one of the two intersection points of the range ellipse and the range circle is selected, if it is located in the beam forming direction and beam spread of the transmitted sensing signal. As an embodiment variant, another parameter that can be used in message 0407 between the first sensing device 0401 and the second sensing device 0402 is beam alignment. For example, the first sensing device (e.g. gNB or UE) 0401 may keep track of beamforming parameters (e.g. angle, focal point) that it uses for sensing and/or communication with a target (device). By communicating one or more of such beamforming (i.e. beam alignment) parameters, possibly in conjunction with location of the first sensing device and/or target (device), to other gNBs or UEs (e.g. acting as a second sensing device), the other gNBs or UEs can then apply beamforming parameters by adjusting for its own location relative to the first sensing device and/or target (device) to facilitate a smooth transition (i.e. with minimal or no interruption) of communication and/or sensing of the target. Similarly, in case of cooperative sensing or communication, the first sensing/communiation device can communicate such parameters to a second sensing/communication device. By aligning the beamforming patterns between the first sensing/communication device and second sensing/communication device, sensing of a target (device) and/or communication with a target (device) can be used to maximize the coverage of a target and/or reduce interference and/or enable sensing from different angles. Furthermore, if a target (device) is capable of beamforming itself for communication and/or sensing, information about beamforming may be shared between the target (device) and/or the first and/or second sensing device, so that beamforming between the target (device) and/or the first and/or second sensing device can be aligned, e.g. in order to reduce interference.

In another variant, the first sensing device 0401 may stop tracking the target (device) 0400 a predetermined time after the initiation of the handover, thus not requiring extra signaling from the second sensing device 0402. Optionally, this predetermined time may be based on an estimate of the speed of the target 0400 or a signal quality change rate. It is also possible to keep the monitoring as long as the first sensing device 0401 is able to detect the target (device) 0400, reducing thus the probability of losing the tracking. However, because of the low quality of the sensing at the end of the handover (when the target 0400 is getting far from the first sensing device 0401), it is possible to discard or at least weigh down the measurements to keep the estimate accurate.

(CONDITIONAL) SENSING HANDOVER PROCEDURE: OPERATION OF TARGET UE

In the description of this embodiment related to Fig. 7 so far, the target 0400 may have not been involved in the sensing mobility procedure, in particular, if wireless signals 0408, 0410 and 0411 are the pure reflection of sensing signals 0406 and 0409, e.g., a radar-based sensing signal such as chirp signal, respectively.

However, the target (device) 0400 may include the capabilities of a mobile device such as a UE in a wireless telecommunications system. The UE may therefore be able to measure the quality of the sensing signals distributed by sensing devices such as the first sensing device 0401 and the second sensing device 0402. This information may also be communicated to the sensing devices in, e.g., messages 0408 and 0411. This information can be used by the first and second sensing devices 0401 and 0402 to take the handover decision in the sensing mobility procedure.

This sensing signal broadcasted by a sensing device can be used - independently of other aspects in the rest in this embodiment -- by a target (device) to select a sensing device as its preferred monitoring device or transmitting device. Monitoring device refers to a device performing sensing monitoring tasks, in particular, tasks to sense the target (device). Transmitting device refers to a device transmitting sensing signals. In particular, sensing devices may broadcast reference sensing signals in a periodic fashion similar to the master information block (MIB) and the system information block (SI Bl) in a 5GS system. Such reference sensing signal may correspond, e.g., to an existing MIB/SIB1 or a radar chirp signal featured by a special physical sensing cell identifier (PSCI), an identifier identifying the sensing device capable of performing sensing services. A sensing device may use multiple beams to provide sensing services in different sectors around the sensing device and each of those beams may also be featured by a beam identifier. A target (device) may measure the sensing reference signals and select a (preferred) target sensing device based on the measured sensing signals. The target (device) may select the preferred target sensing device by attaching/registering/connecting to the (preferred) target sensing device. Alternatively, the target (device) may indicate a preference for a target sensing device in an RRC or a non-access stratum (NAS) message when attaching/registering to the network. Alternatively, a base station or sensing function (SF) in the core network may receive measurement reports from the target (device), e.g., derived from measurements of the sensing signal. These measurement reports may include a field/flag indicating a (preferred) target sensing device and/or whereby the measurement results in the measurement report are used by the base station or SF to determine which sensing signals or particular beams have the best signal quality and use this information to derive which transmitting device these signals/beams originated from and/or which monitoring device is in vicinity of the target and that may be capable of sensing the target. This may be used, e.g., to select the respective sensing device as (preferred) target sensing device (transmitting device and/or monitoring device) or perform other cooperative sensing procedures as described in this invention. In a further embodiment that can be combined with other embodiments, it may be required to determine if a monitoring device in vicinity of the target can receive a (reflected) sensing signal transmitted by a transmitting device. This may be done by using the estimated location of the target and monitoring device, possibly in addition using information about the environment (e.g. buildings in vicinity that may block signals, to derive (e.g., by using raytracing or using measurements of monitoring device or other UEs in vicinity or historical measurements of UEs in that vicinity (e.g. as provided by a network data analytics function (NWDAF))) that the target and monitoring device have line of sight and/or are expected to be at a location where it should be able to receive the (reflected) signals from the transmitting device.

Whether a target (device) requests or not, the sensing service may be implicitly or explicitly indicated to the (preferred) sensing device, e.g., gNB when the target (device) performs, e.g., Random Access. It may be implicitly indicated by using communication resources (e.g., a resource block) reserved for sensing or explicitly indicated by indicating it e.g. using a sensing request field/flag in a RRC Connection Request, or a field/flag in a UE Capability Information RRC message, or indirectly identified by a feature set ID, or indirectly identified by the UE capabilities provided by the AMF based on the identifier (e.g., a subscription concealed identifier (SUCI)) that is sent while attaching/registering to the network, or by the subscription information (e.g. as stored in the unified data management (UDM)) linked to the UE identifier (e.g., SUCI) that is sent while attaching/registering to the network, or by using another RRC or NAS message.

Additionally, the first sensing device 0401 of Fig. 6 may also know which sensing device should receive message 0407 if sensing devices around the first sensing device 0401 broadcast a baseline sensing signal, e.g., similar to the synchronization signals broadcasted by gNBs in the 5G communication system, that is either measured or reflected by the target 0400. If measured, measurements may be sent by the target (device) 0400 to the first sensing device 0401 as part of message 0406. The measurements may refer to the signal strength of the broadcasted sensing signals by different sensing devices. Based on these measurements, the first sensing device 0401 may know which sensing device should take over, e.g., the second sensing device 0402.

Additionally, or alternatively, the broadcasted baseline sensing signal as sent by other sensing devices in vicinity may include some identification information related to the originating sensing device. The first sensing device 0401 may compare the signal strength of the received broadcasted baseline sensing signals and/or determine whether or not these are line of sight or reflected by target 0400. If determined that the signal was reflected by the target 0400 and the quality of the received signal is good, it implies that the target (device) 0400 is in coverage of the sensing device that transmitted the respective baseline sensing. Alternatively, the target (device) 0400 may take this handover decision by itself (i.e., a conditional sensing handover). To this end, the target (device) 0400 is configured with a policy that specifies the conditions under which it has to request the sensing handover. These conditions may be configured by the SF or by a sensing device, e.g., the first sensing device 0401, e.g., a gNB or a gNB central unit. The conditions may refer, e.g., to a certain quality of the received sensing signal. When the conditions are met, the target (device) 0400 informs the first sensing device 0401 which second sensing device should take over the sensing tasks. For instance, if the target (device) 0400 measures a good quality of the sensing signal 0409, the target (device) 0400 may inform the first sensing device 0401 to release the sensing activity , and may inform the first sensing device 0401 (e.g., using the same message) that the second sensing device 0402 needs to take over the sensing of the target (device) 0400, upon which the first sensing device 0401 may inform the second sensing device 0402 about this (e.g. over the Xn interface), whereby it may transmit one or more parameters related to the target (e.g. a monitored state) to the second sensing device 0402 as described in other embodiments of this invention. Alternatively, the target (device) 0400 may directly inform the chosen target sensing device, e.g., the second sensing device 0402, that it should start performing sensing activities. This can be done if the target (device) 0400 accesses the sensing and/or communication service provided by the target sensing device, e.g., by performing random access, or sending an RRC message. The second sensing device 0402 may send a message to the first sensing device 0401 that it has started performing sensing of target device 0400 and may request one or more parameters related to the target (e.g., a monitored state) from the first sensing device 0401. Upon receiving such message(s), the first sensing device 0401 may transmit one or more parameters related to the target to the second sensing device 0402 as described in other embodiments of this invention, and may stop sensing of the target device 0400.

Note that the terminal device incorporated/carried by the device may not be a sensing device itself. In such case, the condition may not be a threshold sensing parameter, but e.g. a signal strength condition of a regular reference signal from a base station (e.g. PSS, SSS, SSB, ...). For instance, a first sensing device may configure a target (e.g., UE) with some threshold parameters for performing a conditional handover for sensing of the target 0500 (e.g., the strength of such regular signal from a base station). When the target (e.g., UE) determines that its signal parameters deviate from the configured parameters, the target (e.g., UE) triggers the conditional sensing handover procedure towards a second sending device. Here, network may be RAN or a network function (NF) in the CN or an AF. Alternatively, if the sensing devices are realized by means of gNB distributed units, or smart repeaters, or reconfigurable intelligent surfaces (RIS), then the central unit of a gNB may coordinate the sensing activities.

Alternatively, the target (device) 0400 may inform a network function in the core network, e.g., the SF, and the SF can coordinate sensing activities of the first and second sensing devices 0401 and 0402.

In another variant, the sensing device in charge of sensing the target device at a specific point of time is the base station to which the target device is connected. If the target device performs a communication handover according to TS 38.300 from a source base station to a target base station, the sensing of the target device may be performed by means of the source base station as long as the handover to the target base station is not complete or if the target base station is not able (e.g., not capable of or too overloaded to perform wireless sensing) to take over sensing of the target device. If the target base station is able to take over the sensing of the target device from the source base station, it may start sensing of the target device based on the target device information (e.g., identity, location) it received from the source base station.

SENSING RECEIVER/TRANSMITTER HANDOVER PROCEDURE

In the case of Fig. 7 each sensing device includes both a receiver and a transmitter, but the messages included in Fig. 7 and described above may also be applicable to implement, e.g., other handover procedures, e.g., 033 and 034, in Fig. 6.

In the case of a sensing receiver handover procedure as in 034, the messages/signals 0408 and 0410 of Fig. 7 do not apply, and thus the handover procedure is under control of the sensing receiver (S_Rxl) in the first sensing device 0401. This case illustrates a sensing handover procedure that moves (where here and in the following "to move" can be understood with the meaning of "to hand over") from a centralized sensing capability at the first sensing device 0401 towards a distributed sensing capability distributed over the first and second sensing devices 0401 and 0402. When the target 0400 is at the first location 0403, sensing transmitter and sensing receiver are co-located in the first sensing device 0401. When the active transmitter moves (i.e., is changed/handed over) to the second sensing device 0402 (e.g., because the target 0400 moves to the second location 0404, i.e. closer to the second sensing device 0402), the sensing transmitter and sensing receiver are not colocated anymore and message 0407 and sensing signals/messages, 0409 and 0411 form a closed control loop. In this case, message 0407 may also contain control information to steer the sensing transmitter of the second sensing device 0402, e.g., time synchronization information or signal parameters such as a beam direction.

In the case of a sensing transmitter handover procedure as in 033, the messages/signals 0409 and 0411 do not apply, and thus the handover procedure is under control of the sensing transmitter (S_Txl) in the first sensing device 0401. This illustrates a sensing handover procedure that moves from a centralized sensing capability at the first sensing device 0401 towards a distributed sensing capability distributed over the first and second sensing devices 0401 and 0402. When the target 0400 is at the first location 0403, sensing transmitter and sensing receiver are co-located. When the transmitter moves (i.e., is changed/handed over) to the second sensing device 0402, the sensing transmitter and sensing receiver are not co-located anymore and sensing signals/messages 0405 and 0408 as well as message 0412 form a closed control loop. In this case, message 0412 may also contain control information to steer the sensing transmitter of the first sensing device 0401 based on measurements of the sensing receiver of the second sensing device 0402. Message 0407 serves to indicate to the sensing receiver of the second sensing device 0402 the features of the sensing signal that it is expected to receive.

COOPERATIVE SENSING PROCEDURES

In accordance with another embodiment, a cooperative sensing procedure is described in Fig. 8, e.g., related to 031+032 in Fig 6. In this procedure, at least two sensing devices 0501 and 0502, e.g., two base stations or two UEs or a base station and a UE, are involved in the wireless sensing of a target 0500, e.g., a moving target, e.g., a car, a vehicle mounted relay, a UAV, or a person, that moves from a first location 0503 to a second location 0504 and then to a third location 0505. A cooperative sensing procedure may be important because a single sensing device may not have line of sight (LoS) with the target 0500 always, e.g., obstacles such as buildings may obstruct the LoS. For instance, in Fig. 8, a first obstacle 0507 blocks the LoS between the second sensing device 0502 and the target 0500 at the first location 0503. For instance, in Fig. 8, a second obstacle 0506 blocks the LoS between the first sensing device 0501 and the target 0500 at the second location 0504. To address this situation, the sensing system involves several procedures:

A first procedure that can be combined with other embodiments refers to a procedure that allows a sensing device to create and maintain its map of its sensing area or sensing volume. This procedure may be triggered by the sensing device itself, the sensing function (SF) 0510 in the 5G core network 0509, or an external AF through the NEF. The sensing area is defined as the area around the sensing device that can be sensed by the sensing device. The sensing volume is defined as the volume around the sensing device that can be sensed by the sensing device. The sensing area or volume is determined by the sensing range (how far the sensing device can sense assuming free space) of the sensing device and the obstacles (e.g., fixed obstacles) in its environment that may limit the sensing of the sensing device. The creation of this map can be done, e.g., by configuring the sensing device or SF with a map based on the known environment (e.g., buildings in a city) and location of the sensing device (e.g., gNB). This map can be retrieved, e.g., from an external application, through the NEF. This map can be created by actively sensing the environment, e.g., by beaming a sensing signal around the sensing device, and storing, e.g., in a data base co-located with the sensing device or in the SF 0510 in the 5G core network 0509, the locations of obstacles around the sensing device and determining the sensing area or sensing volume of the sensing device. This procedure can be repeated in a periodic manner to adapt the map according to seasonal changes (e.g., vegetation). The map should also be weather dependent (e.g., rain).

A second procedure that can be combined with other embodiments refers to a procedure for the configuration of cooperative sensing devices in a sensing device or the configuration of relationships between sensing devices in the SF 0510. In particular, o The SF 0510 may retrieve the map obtained by a sensing device and store it in a data base. The SF 0510 may determine white spots triggering the deployment of additional sensing devices. The SF 0510 may determine the sensing neighbors for each sensing device. o The first sensing device 0501 may be informed by the SF 0510 about the second sensing device 0502 that it can cooperate with in order to ensure wider/good sensing coverage. In particular, the SF 0510 may inform the first sensing device 0501 which sensing devices, e.g., the second sensing device 0502, can perform sensing at the limits of the sensing area or sensing volume of the first sensing device 0501. For instance, it can inform the first sensing device 0501 that the second sensing device 0502 can sense the target at the second location 0504. o To avoid interferences during sensing, the sensing devices may (1) have been configured, e.g., by the core network 0509, e.g., the SF 0510, with suitable timing/frequency resources (e.g., sensing signals using different timing or frequencies or codes) over respective first and second interfaces 0511 and 0512 or (2) communicate to each other over a respective third interface 0513 the resources that they are currently using for sensing to avoid using the same resources, a situation that may lead to a decrease in the sensing accuracy during operation. In certain cases, the sensing devices may require a tight cooperative sensing procedure, e.g., by broadcasting the same sensing signal in a coordinated manner, e.g., with a small phase shift to create a directional beam. In this case, the core network 0509, e.g., the SF 0510, or a central unit of a gNB may coordinate the suitable parameters.

A third procedure refers to a cooperative sensing procedure in which at least two sensing devices cooperate to sense a target by simultaneously sensing the target and (i) informing each other about the sensed features (e.g., location) of the target or (ii) combining the received signals to obtain a more accurate sensed signal. This simultaneous sensing may be: o 031+032 as in Fig. 6: at least two transmitters and at least two receivers. o 036 as in Fig. 6: a single transmitter and at least two receivers. o 037 as in Fig. 6: multiple transmitters and a single receiver.

A fourth procedure that can be combined with other embodiments in this invention refers to a procedure in which a central entity, e.g., the SF 0510 in Fig. 8 or an application function, gathers the sensed information of one or multiple targets as collected by the sensing devices. The central entity is in charge of linking the sensed information to a given target independently of the sensing devices used to sense the target. In applications in which the target is not linked to a device UE, the central entity may allocate an identifier to the target (e.g., the central entity may allocate a new (e.g., randomly chosen) identifier when a new and/or distinct object has been detected, or may allocate an identifier that is associated with a set of target identification information (e.g., matching criteria for a target), or may allocate an identifier based on a target identifier provided by an application or may allocate an identifier based on a subscription identifier associated with the sensing service and/or the sensing of the target, or may allocate an identifier based on an identification of the sensing session). This identifier may have also been allocated, e.g., initially, by a sensing device. This identifier may be a temporal identifier. This identifier may also be updated in a regular basis or when a given sensing device starts sensing the target, e.g., after a sensing handover procedure. This identifier may be linked to a subscriber identifier, e.g., the Subscription Permanent Identifier, once the managing (i.e. central) entity has identified the target In case the target is linked to a device UE (e.g., the target carries or encompasses a UE), the identity (or pseudonym linked to that identity) of the respective device UE (e.g., the Subscription Permanent Identifier (SUPI) related to that device UE) may be used as identifier of the target. For instance, a sensing identifier might be created that is linked to the SUPI of the UE and the binding is stored in a data base in the telecommunication system, e.g., in the UDM, AUSF, etc.

A fifth procedure that can be combined with other embodiments refers to a procedure in which a central entity, e.g., the SF 0501 of Fig. 8 or an application function, gathers the sensed information of one or multiple targets as collected by the sensing devices. The central entity is in charge of combining the sensed information from one or multiple targets. In particular, this means that sensing devices may send all sensed information of targets, e.g., location, speed, vital signs, etc to the SF or another managing (i.e. central) entity. The managing entity is then in charge of keeping track of a target when it moves across the sensing boundaries of different sensing devices.

For instance, in Fig. 8, the first sensing device 0501 senses the target 0500 at the first location 0503. When the target 0500 moves towards the second location 0504 that is not in the sensing area of the first sensing device 0501 due to the second obstacle 0506, the first sensing device 0501 informs the second sensing device 0502 by means of a message over the third interface 0513 (e.g., an Xn interface when the first and second sensing devices 0501 and 0502 are base stations or an Uu interface when the first and second sensing devices 0501 and 0502 are a base station and a UE or a PC5 interface when the first and second sensing devices 0501 and 0502 are two UEs) ensuring that the second sensing device 0502 is ready to start sensing the target 0500. The first sensing device 0501 may know which sensing device to inform by looking up a neighbor table that has been configured in the first sensing device 0501 in the context of the second procedure. Additionally, or alternatively, a network function, e.g., the SF, 0510, in the core network 0509 or an application function may inform/request the second sensing device 0502 about the need to start sensing the target 0500 when the target is about to move out of the sensing coverage area/volume of the first sensing device 0501.

It is worth noting that a (conditional) sensing handover procedure as described in the above embodiment and in Fig. 7 may not be feasible due to the presence of the first and second obstacles 0507 and 0506 that avoid smooth transition (in other words, the first sensing device 0501 may not observe a slow decrease in, e.g., the signal strength of the sensing signal from the target 0500, but this decrease may be abrupt); thus, the first sensing device 0501 needs to make aware the second sensing device 0502 well in advance of the upcoming target 0500 to ensure a proper sensing coverage. Similarly, even if the target (UE) 0500 can measure the reference sensing signals of other sensing devices, it may be that at the first location 0503 the first sensing device 0501 is the preferred option and it is only when the target 0500 moves to the second location 0504 that the measurements of the sensing signals by the target (UE) 0500 indicate the need of a sensing handover or triggers the initiation of cooperative sensing.

As described for Fig.7, sensing handover may be triggered by the network, e.g., when a first sensing device (e.g., base station) detects that it cannot sense well a target (e.g., it moves out of its coverage area or it moves towards the coverage area of a second sensing device), the first sensing device informs a second sensing device. These conditions may be based on a local policy or based on a configuration by a central controller (e.g., a gNB-CU, or a sensing network function). Conditional sensing handover may be triggered by the target (which incorporates or carries a terminal device (e.g., UE)) based on conditions configured in the target (e.g., UE) which may have been configured by the network beforehand, as described for Fig. 7. When the target 0500 moves towards the second location 0504 that is at the limit of the sensing area/volume of the first device or the first sensing device 0501 has detected an obstacle 0506 (e.g., due to a radar sweep of the area) or observes a sudden drop in receiving reflected sensing signals from target 0500,, the first sensing device 0501 may inform the second sensing device 0502 by means of a second message over the third interface 0513, e.g., the Xn, Uu, or PC5 interface. Additionally/alternatively, the NF 0510 may also inform the second sensing device. This ensures that the second sensing device 0502 starts sensing as soon as possible. In case of conditional handover, the terminal device carried/incorporated by the target 500 may inform the second sensing device 0502 to start sensing of target 0500 as soon as it notices a drop in receiving sensing signals or other (reference) signals (e.g., PSS, SSS) from the first sensing device and/or may inform the second sensing device 0502 to start sensing of target 0500 as soon as it can measure sensing signals or other (reference) signals (e.g., PSS, SSS) from the second sensing device. Additionally or alternatively, the terminal device carried/incorporated may be configured by the network (e.g., SF or by the first sensing device) about obstacles and/or areas with limited or no coverage and/or with information that maps a set of location/area/volume information (e.g., as denoted by a set of coordinates or GAD shapes as defined in 3GPP TS 23.032 or zone IDs as defined in 3GPP TS 38.331) to one or more sensing devices (identified e.g. by its cell ID or sensing signal identifier) which it can request to initiate sensing of target 0500. The terminal device carried/incorporated by the target 500 may use this information as (additional) condition to trigger handover, i.e., if it detects that it is currently located (e.g., through built-in GNSS receiver to determine its location) in a particular location/area/volume, it can request handover to a sensing device indicated in the configured information. At the third location 0505, both the first and second sensing devices 0501, 0502 can simultaneously sense the target 0500 since the third location 0505 is in the sensing area of both sensing devices. To this end, the first sensing device 0501 may have continued sensing of target 0500 based on the target's trajectory and/or the determination of the size of obstacle 0506, or based on a pre-configured time after it has not been able to sense target 0500 anymore (e.g., a retry timer). The first sensing device 0501 may receive information from the second sensing device 0502 (or NF 0510) about the current location and/or trajectory of target 0500 that the first sensing device 0501 may use to determine whether to continue or restart sensing of target 0500. In case of conditional handover, the terminal device carried/encompassed by the target may inform the first sensing device 0501 to initiate/continue sensing of target 0500 as soon as it can receive the sensing signals (or other signals) from the first sensing device 0501 again. Sensing measurements can be sent to the SF 0510 over the first and second interfaces 0511 and 0512 and the SF 0510 can combine the measurements to increase the sensing accuracy. COOPERATIVE SENSING WITH MULTIPLE DEVICES FORMING A SENSING ARRAY

In accordance with another embodiment, a cooperative sensing procedure is described in Fig. 10 in which multiple sensing devices are used as a sensing array to sense a target (device) 0700 at a given location. In the example of Fig. 10, six sensing devices 0701 to 0706 are involved in the sensing procedure and three of them constitute a dynamic sensing array 0709 to 0712. As the target 0700 moves, the respective members of the sensing array 0709 to 0712 are updated, in particular, with reference to Fig. 10, when:

• the target 0700 is at a first location 0713, a first sensing array 0709 is created, and the members are the first to third sensing devices 0701, 0702, and 0703.

• the target 0700 is at a second location 0714, a second sensing array 0710 is created, and the members are the second to fourth sensing devices 0702, 0703 and 0704.

• the array is at a third location 0715, a third sensing array 0711 is created, and the members are the third to fifth sensing devices 0703, 0704 and 0705.

• the array is at a fourth location 0716, a fourth sensing array 0712 is created, and the members are the fourth to sixth sensing devices 0704, 0705 and 0706.

The number of members in a sensing array may depend on at least one of the required sensing accuracy, the distance to the target 0700, and the parameter (location, speed,...) to sense. The number of members may be configured by a coordinating entity as below and may depend also on a policy configured by a given entity.

The members of the sensing array may require coordination of their sensing signals, e.g., the transmitted sensing signal may be different or the same sensing signal with, e.g., a certain delay or phase shift with the purpose of creating a beam focused on the target (device).

The members of the sensing array may require coordination of their sensing signals, e.g., the sensed sensing signal may be sent to an entity that may mix the sensed sensing signals of all the members of the sensing array or the estimated sensed parameters may be sent to an entity that may combine the estimated sensed parameters obtaining sensed parameters of higher accuracy. The entity may refer to the entity providing coordination.

The entity providing coordination may be one of the sensing devices or by a central controller, e.g., a central unit in a gNB or a NF, e.g., the SF, of the CN, or an AF.

When the target (device) 0700 moves, the members of the sensing array 0709 to 0712 may be updated using one of the embodiments above. For instance, when moving from the first location 0713 to the second location 0714, the created first sensing array 0710 may take the handover decision from the first sensing device 0701 to the fourth sensing device 0704 so that the first sensing array 0709 becomes the second sensing array 0710.

IMPROVING 5G COMMUNICATION HANDOVER PROCEDURES BY MEANS OF SENSING

Communication systems such as 5G rely on mobility procedures such as handover and conditional handover procedures (TS 38.300) to provide service to UE when they move through the 5G system (5GS), in other words, to get a UE connected to the 5GS through multiple gNBs. A communication system can benefit of sensing capabilities to improve such mobility procedures.

For instance, in an embodiment regarding a handover procedure for a mobile device in a cellular network (as described in Section 9.2.3.2.1 in TS 38.300), the handover decision of the source gNB in step 2 may not only depend on measurement control and reports exchanged in step 1, but also on accurate sensed information of the UE similar to the embodiments described in the context of Fig. 7. In particular, message 3 "Handover request" in Section 9.2.3.2.1 in TS 38.300 may correspond to and be enhanced by means of message 0407 of Fig. 7 and message 4 "Handover request acknowledgment" in Section 9.2.3.2.1 in TS 38.300 may correspond to and be enhanced by means of message 0412 of Fig. 7.

In an additional particular embodiment, sensed information related to the accurate location (position, speed,...) of the UE can improve mobility procedures in deployments such as depicted in Fig. 7 where a target 0500 (e.g., a UE) moves from the first location 0503 to the second location 0504. Additional information that may be sensed and exchanged with this purpose may include:

• the shape or size of the target (device) may(e.g., a truck with a UE installed), or

• information that the UE is carried on the body of a person, if this is detectable, or

• information on which side of the body such UE is worn (e.g., which side is obstructed by the person) or

• Its orientation.

While the reported measurements at the first location 0503 of Fig. 8 may usually not trigger a communication handover as per TS 38.300, the additional sensed information can help the first sensing device 0501 implementing the source gNB functionality to trigger the communication handover procedure towards the second sensing device 0502 implementing the target gNB functionality.

IMPROVING 5G COMMUNICATION BY MEANS OF SENSING Communication systems such as 5G allow UE devices to exchange data over the Uu interface (between UE and gNB) or over the PC5 interface (between 2 UEs). In the case of the Uu interface and dynamic scheduling (TS 38.300), communication resources are allocated to a UE by the gNB upon reception of a scheduling request (SR) sent by the UE. The decision on allocating resources and the specific allocated resources depends on, e.g.:

• measurements by UE and Network, e.g., channel quality indicator (CQI);

• buffer status report, or

• QoS requirements, or

• associated Radio bearer,

• etc.

Once the gNB has taken the decision, in particular, a scheduling decision, the gNB sends a message, e.g., a DCI (Downlink Control Information) message, specifying the allocated time and frequency resources.

Resource scheduling (and thus communication) can be improved by means of sensing by taking into account the history of CQI measurements or information regarding the mobility pattern (location, speed,...) of UEs or VMRs (vehicle mounted relays) or other type of (mobile) access devices. If a UE/VMR reports its mobility pattern, this information can be combined with the history of CQI measurements reported by the UE/VMR, to better estimate the actual CQI value of a UE or VMR.

Furthermore, resource scheduling can also be further improved by relying on sensed data obtained by sensing devices involved in this disclosure. The reason is that sensing devices co-located with communication devices such as gNBs can obtain/sense detailed information of the mobility pattern of UEs or other targets equipped with a UE such as a UAV or detect obstacles that may hamper communication or reduce signal quality. This allows gNBs to better predict the expected channel quality of the communication link between UE and gNB, and in this manner, perform better resource scheduling decisions. Furthermore, by using wireless sensing the location/mobility of a target equipped with a UE can be followed even if the UE is not communicating (e.g., low-power loT (Internet of Things) device that is sleeping but still moving, e.g. a sensor attached to a (moving) person/object that communicates intermittently or with large time intervals between subsequent communication, or an loT device that needs to harvest additional energy first before it can communicate again, or a very fast moving device, or a device for which its communication signals are "temporarily" having very low signal strength/quality or are blocked (e.g. when driving in a tunnel). Using the sensing information of a target and/or its environment, the handover or involvement of other sensing devices in cooperative sensing of the target can already be prepared (e.g. by providing the other sensing devices with data about the target and/or the UE equipped with the target, such as identity, location, speed, trajectory, ...).

For instance, in an embodiment, consider Fig. 9 showing a cell with a communication/sensing area where a base station 060 is capable of communication and sensing. There are first and second UEs 061 and 062. Fig. 9 includes a gray scale (indicated by different hatching densities) denoting a CQI measured by the UEs 061 and 062 at different locations in the communication/sensing area of the base station 060. At the current location, both the first and second UEs 061 and 062 report a high CQI value (dark pattern). However, based on the mobility pattern/trajectory of the UEs 061, 062 indicated in Fig. 9 by means of the arrow next to the UEs 061, 062, it is clear to see that the CQI value of the first UE 062 will remain high, but the CQI value of the first UE 061 is going to go down abruptly and remain low (white color). A sensing-capable device such as the base station (e.g., gNB) 060 can use this information to, e.g., allocate all resources to the first UE 061 as long as it has a high CQI and is at a suitable location and then once the first UE 061 has a worse coverage, allocate resources to the second UE 062. This allows improving the overall QoS in a sensing-capable 5GS.

In order to enable this embodiment, the user has to give consent to the network operator to make use of his/her sensed mobility pattern/trajectory with the purpose of improving the wireless communication capabilities. Such a user consent preferences may be stored in a user database (e.g., the UDM or UDR) as part of the subscription of the user. Upon registration of a UE of the user to the network or upon initiation of the sensing service or location service, the AMF, AUSF, SF, LMF, or other core network function may retrieve information about the user consent from the user database before proceeding with sensing of the UE. Such a user consent may also be collected by a visited network (e.g.,VPLMN) when the user registers with the serving network. The VPLMN (e.g., AMF or RAN) may also retrieve such a user consent from the user database (e.g., UDM/UDR) in the home network (HPLMN) or the home network may also provide the visited network with such user consent preferences after, e.g., primary authentication.

HANDOVER TAKING INTO ACCOUNT OBJECT SIGNAL REFLECTION/OBSTRUCTION

An additional embodiment that can be combined with the other embodiments or can be implemented independently is depicted in Fig. 11. In this embodiment, object signal reflection and/or obstruction is taken into account during handover. A first sensing device 0801 (for example a gNB), which includes a sensing transmitter S_TX1 and optionally a sensing receiver S_RX1 may be capable of distributed wireless sensing of a target object and/or target device 0800 (i.e., "target (device)" in short). To this end, it may transmit sensing signal(s) 0820 that may be part of a beam (indicated in hatching). The sensing signals 0820 may be reflected by the target (device) 0800, resulting in reflected signals 0821, which may be received by a receiving sensing device 0810 (for example a mobile device (e.g., UE)), which includes a sensing receiver S_RX10 and optionally a sensing transmitter S_TX10, which is called a "receiving sensing device" since it may not transmit sensing signals 0842). Based on the sensing signals received by the receiving sensing device 810 and optionally by a second sensing device 802 (e.g. another gNB), the first and/or second sensing devices 801 and/or 802 (and/or the receiving sending device 810) or a sensing function (e.g. a sensing control function in the core network or operated by a gNB-CU, not shown in Fig. 11) may collect the sensing measurements and/or intermediate calculations/sensing results from the various sensing devices (transmitted e.g. using signals 841 and 824) and calculate a characteristic (e.g. state/parameter such as location, size, shape, movement, temperature) of the target 0800. If at some point in time, the first sensing device 0801 or the receiving sending device 0810 or a sensing function (e.g. a sensing control function in the core network or operated by a gNB-CU) determine that another sensing device needs to get involved in transmitting (or receiving) of sensing signals (e.g., because of a handover or for cooperative sensing), it may transmit a signal to one or more neighboring sensing devices that it may want to request to get involved in the sensing of the target (device) 0800. In the example shown in Fig. 11, possible candidate sensing devices could be the second sensing device 802 and a third sensing device 0803, and signals 0822 and/or 0832 may be used to inform the candidate sensing device (note: instead of separate signals 0822 and 0832 this may also be done by a single broadcasted/multicasted signal). Such signals may include information about the target (device) 0800, such as location coordinates or area or direction information, and may include information about other sensing devices in the vicinity (which may include e.g. receiving sensing devices that are taking part in distributed sensing), such as their location coordinates. However, not all neighboring sensing devices may be good candidates to be involved in the sensing of a particular target (device). For example, the target (device) 0800 may obstruct sensing signals or may reflect sensing signals towards a certain direction that hamper receiving of the (reflected) sensing signals from reaching one or more of the receiving sensing devices due to target (device)'s size, shape, material composition. In the particular deployment as depicted in Fig. 10 where distributed sensing using the receiving sensing device 0810 is used, the signals from the third sensing device 0803 would not be able to reach the receiving sensing device 0810 (and possibly also not sensing the second device 0802), and hence may not be a good candidate to be involved in the sensing of the target (device) 0800. In order to determine if a neighboring device is a good candidate, it is important to detect whether the sensing signals transmitted by the candidate sensing devices would actually be able to be received by one or more sensing devices involved in the sensing of the target (device) 0800. In order to achieve this, candidate sensing devices may be instructed to initiate sending a set of initial sensing signals (e.g., sensing reference signals (as described above), possibly in different directions) and other sensing devices with reception capabilities such as the receiving sensing device 0810 may be requested to monitor whether they are able to receive those initial signals and/or detect that those signals have been reflected by the target (device) 0800. To this end, candidate sensing devices may be instructed to perform the transmission of those initial signals in sequence or in a different frequency range or using a different multiple access approach, to distinguish them at the receiving sensing devices (or the sensing function or other sensing device that collects and processes the sensing measurements and/or (partial) results from the receiving sensing devices), or insert an identifiable code that enables the receiving sensing devices (or the sensing function or other sensing device that collects and processes the sensing measurements and/or (partial) results from the receiving sensing devices) to distinguish them. These initial transmissions may be similar to the reference sensing signals mentioned in other embodiments. Based on the analysis of these initial transmissions, it will become clear which of the candidate sensing devices are able to transmit signals that can be received (after reflection by the target (device) 0800) by one or more other sensing devices. The sensing device (or sensing function) that decides on whether to involve another sensing device to transmit sensing signals (e.g., to initiate handover or collaborative sensing) can then make an informed decision which candidate sensing devices to consider since their sensing signals can be received and which ones not, and may further instruct one or more candidate sensing devices from which the sensing signals can be received accordingly, e.g., by sending additional signals/information to initiate handover as described in other embodiments. The candidate sensing devices from which the sensing signals cannot be received may be removed from the list of candidate sensing devices.

In the example shown in Fig. 9, the transmission of sensing signals 0833 by the third sensing device 0803 and the resulting reflections are unlikely to be able to be received by the receiving sensing device 0810 (and the second sensing device 0802), since the third sensing device 0803 is hidden behind the target (device) 0800, whereas sensing signals 0823 transmitted by the second sensing device 0802 and the resulting reflections are likely to be able to be received by the receiving sensing device 0810. The receiving sensing device 0810 may inform the first sensing device 0801 (or a sensing function) (e.g. by sending information about this via the signal 0841) that it is able to receive the signals from the second sensing device 0802 but not from the third sensing device 0803, and hence the second sensing device 0802 will be selected for handover or collaborative sensing. In summary, a sensing device or a device that supports a sensing function may support a method for selecting another sensing device for handover or collaborative sensing, whereby it determines a set of candidate sensing devices, (optionally) instruct the set of candidate sensing devices to initiate transmission of sensing signals (whereby the instructions may include information about a target (device) and/or information about other sensing devices), further (optionally) instruct a set of other sensing devices (which may be receiving sensing devices in case of distributed sensing) to listen for these sensing signals, and select a candidate sensing device for handover or collaborative sensing, e.g., based on whether or not one or more of the set of other sensing devices is able to receive these sensing signals (that may be reflected by a target (device)). The set of other sensing devices may send information whether or not they are able to receive the sensing signals to the sensing device or the device that supports a sensing function that is responsible for selecting another sensing device for handover or collaborative sensing.

Alternatively or additionally, a sensing device (or sensing function) that needs to select another sensing device for handover or to initiate collaborative sensing from a set of candidate sensing devices may determine or request/receive the (relative) position of the candidate sensing devices (e.g., through a message exchange with the candidate sensing devices (e.g., through signals 822/824 and/or 832/834 in Fig. 11) or from a location function or sensing function (e.g. location management function in the core network, not shown)). It may also determine the (relative) position of the target (device) (e.g. through a sensing function), and/or the receiving sensing devices (e.g. through signals 840/841 in Fig. 11 or a location function or sensing function) that may be involved in distributed sensing. Together with information about the target (device), such as its estimated/sensed position, size, shape, material, a sensing device (or sensing function) that needs to select another sensing device for handover or to initiate collaborative sensing from a set of candidate sensing devices may determine by calculating signal trajectories (e.g. through raytracing) whether sensing signals transmitted by candidate sensing devices can be received (after reflection) by one or more other sensing devices, including receiving sensing devices (such as the receiving sensing device 810), and/or whether their signals would be blocked/obscured by the target (device) or another obstacle. If so, then those sensing devices can be further considered and/or selected as additional sensing devices and/or be instructed to perform handover with. If not, then those sensing devices can be removed from the set of candidate sensing devices.

In summary, a sensing device or a device that supports a sensing function may support a method for selecting another sensing device for handover or collaborative sensing, whereby it determines a set of candidate sensing devices, determines the (relative) position of the candidate sensing devices and the (relative) position and/or other information (such as size, shape, material) of a target (device), and may also determine the (relative) position of other sensing devices that may be involved in the sensing of a target (device) (such as receiving sensing devices in case of distributed sensing), further determine whether signals transmitted by the candidate sensing devices would be able to be received by the other sensing devices (e.g. through by calculating signal trajectories and/or ray tracing) and/or whether their signals would be blocked/obscured by the target (device) or another obstacle, and select a candidate sensing device for handover or collaborative sensing if one or more of the set of other sensing devices is determined to be able and/or is determined not to be obscured by the target (device) to receive these sensing signals (that may be reflected by a target (device)).

Alternatively or additionally, if a receiving sensing device in case of distributed sensing (such as the receiving device 0810 of Fig. 11) also has a transmitter for sensing signals (e.g., S_TX10 which transmit the sensing signals 0842 of Fig. 11), then such receiving sensing device may be instructed (e.g. by a sensing device (e.g., the first sensing device 0801 of Fig. 11) or a sensing function that needs to select another sensing device for handover or to initiate collaborative sensing from a set of candidate sensing) to transmit sensing signals (possibly in different directions). This may be done through signals (such as signal 0840 in case of the receiving sensing device 0810 of Fig. 11), which may include information about the target (device), such as location coordinates or area or direction information, and may include information about other sensing devices in vicinity (which may include e.g. receiving sensing devices that are taking part in distributed sensing), such as their location coordinates. After receiving such instructions, the receiving sensing device (e.g., the receiving sensing device 0810) may transmit sensing signals aimed at the target (device) (e.g., the target (device) 0800). Such sensing signals may include a code through which it is possible to identify the receiving sensing device (e.g., the receiving sensing device 0810) that has transmitted these signals. Candidate sensing devices (e.g., the second and third sensing devices 0802 and 0803 of Fig. 11) for handover or collaborative sensing can be instructed to listen to such signal transmitted by the receiving sensing device (possibly reflected by the target (object). If a candidate sensing device (e.g., the second and third sensing devices 0802 or 0803) is able to receive those sensing signals, they may inform the sensing device (or sensing function) responsible for selecting a sensing device for handover or collaborative sensing, that it has received or has not received those sensing signals. If the candidate sensing device is able to receive those sensing signals, then it may be selected for handover or collaborative sensing, since in that case it is also a good candidate for transmitting signals in the inverse direction that may be detected/received by the receiving sensing device (e.g., the receiving sensing device 0810) in case of distributed sensing. If it is not able to receive those sensing signals, then it may not be selected. In summary, a sensing device or a device that supports a sensing function may support a method for selecting another sensing device for handover or collaborative sensing, whereby it determines a set of candidate sensing devices, instruct another sensing device involved in the sensing of a target (device) (such as receiving sensing devices in case of distributed sensing) to initiate transmission of sensing signals (whereby the instructions may include information about a target (device) and/or information about other/candidate sensing device), further instruct a set of candidate sensing devices to listen for these sensing signals, and select a candidate sensing device for handover or collaborative sensing if one or more of the set of candidate sensing devices is able to receive these sensing signals (that may be reflected by a target (device)). The set of candidate sensing devices may send information whether or not they are able to receive the sensing signals to the sensing device or the device that supports a sensing function that is responsible for selecting another sensing device for handover or collaborative sensing.

FURTHER EMBODIMENTS ON (CENTRALIZED) SENSING OF A MOVING TARGET

An additional embodiment for (centralized) sensing of a moving target, that can be combined with the other embodiments of this invention or can be implemented independently, is depicted in Fig. 12 in combination with Fig. 13. In this embodiment, a target 0998 is moving around in an area according to a trajectory 0999. The area is covered by a set of RAN entities (e.g., base stations, small cells, integrated access and backhaul (IAB) nodes, gNB-DU) 0910 (l..m) that are capable of acting as a sensing device (i.e., as sensing transmitter and/or sensing receiver). The RAN entities 0910 may operate under control of one or more RAN controllers (e.g., gNB-CU, RAN network control entity) 0911 (l..n), whereby a RAN controller 0911 may be combined in a single device with a RAN entity 0910, and whereby the RAN entities 0910 or the RAN controllers 0911 are possibly operated/managed by multiple network operators. The RAN entities 0910 together with the RAN controllers 0911 constitute a RAN 0901. The RAN entities 0910 may communicate with the RAN controllers 0911 using a first interface 0903 (e.g., an Fl interface) and may also communicate with each other (not shown in Fig. 12) using e.g. an Xn interface. The RAN 0901 may communicate with a core network (CN) 0900 using a second interface 0902, in particular it may communicate with an AMF 0920 over e.g. a next generation (NG) interface (using the NG application protocol (NGAP)) and/or communicate directly with a Sensing Function (SF) 0930 that may be a service offered by the CN 0901 (e.g., using a tunneled control plane protocol or user plane protocol over the second interface 0902 or a different interface). The SF 0930 may also be deployed (not shown in Fig. 12) as a service in one of the RAN entities 0910 or the RAN controllers 0911 (e.g., as part of its Edge computing environment). The CN 0900 may further consist of a Network Exposure Function (NEF) 0940 to communicate with an Application Function (AF) 0950 using a third interface 0905 (e.g., a N33 interface). In addition to the RAN entities 0910 capable of wireless sensing, also a number of UEs 0990 (l..k) with k>=0 may be capable of acting as a sensing device (i.e., sensing transmitter and/or sensing receiver), and may be present in the area as well. These UEs 0990 may be connected to one or more RAN entities 0910 using a fourth interface 0904 (e.g., a Uu interface), and may also communicate (not shown in Fig. 12) with each other e.g. using a PC5 interface. Note that the selection to which RAN entity 0910 a UE 0990 connects can be independent from the sensing operation. For example, a sensing signal transmitted by a first RAN entity 0910 (1) acting as a sensing transmitter may be received by a first UE 0990 (1) acting as a sensing receiver, whereby the first UE 0990 (1) may not be connected to the first RAN entity 0910 (1), but e.g. in case of Fig. 12 to a fifth RAN entity 0910 (5). The sensing measurement data of the first UE 0990 (1) acting as a sensing receiver may be received by the fifth RAN entity 0910 (5) to which it is connected, which may then forward the measurements to the respective sensing transmitter or to another destination (e.g., a central sensing service, or central repository e.g. in a CN or operated by a RAN controller), based on configuration/policy provided to the respective RAN entity by an SF (or other CN entity or RAN controller), or based on a destination provided by the UE.

An exemplary high-level procedure of how the target 0998 can be sensed whilst moving along its trajectory 0999 is shown in Fig. 13. Not all steps in Fig. 13 may always be required.

In a first step 931 the SF 0930 may determine a target sensing area/volume, e.g., as required for a given application and/or related to the area/volume that can be sensed by one or more sensing devices. This may be determined by, e.g., optionally receiving information 951 about the target sensing area/volume or a set of possible target locations or trajectory information provided by an AF 0950 via the NEF 0940 (i.e., using the third interface 0905). The AF 0950 may also provide other information, such as characteristics of target (e.g., size, shape, identity, speed) and/or expected sensing data (e.g., which sensing results/measurements it would like to receive about the target 0998 (e.g., location, size, sudden movements, regular displacement patterns) and/or the accuracy of the sensing results/measurements). Alternatively or additionally, the target sensing area/volume may be determined by estimating the location or receiving location information of the target 0998, e.g., from one or more RAN entities 0910 or UEs 0990, or e.g. from the target 0998 itself if the target 0998 encompasses a UE or a UE is carried by the target 0998 that may provide its location (e.g., through tracking area information provided during registration or for which the location may be obtained through a Location Management Function (LMF) using radio access technology (RAT)-dependent (e.g., time difference of arrival (TDOA)) or RAT-independent (e.g., global navigation satellite system (GNSS)) positioning and/or position information exchange. Alternatively or additionally, a target sensing area may be provided as part of the subscription information to a sensing service (e.g., stored in the UDM or Unified Data Repository (UDR)), which may be obtained by or provided to the SF 0930 when an application function or UE (e.g. upon registration) triggers activation of a sensing service. Based on a target location and/or target sensing area and/or trajectory information, the SF 0930 may determine a set of sensing devices for sensing of a target (i.e., sensing transmitters and/or sensing receivers) that are currently present/located in the target sensing area or that together cover a target sensing area or that are in vicinity of the target 0998. This may be a subset of all known or registered sensing devices, e.g. the SF 0930 may not select some sensing device because they may be switched off or sleeping, or some may be too overloaded (e.g., with communication tasks) that they should not be selected as sensing transmitter or receiver, or some may have insufficient capabilities for the given sensing task (e.g., if the sensing task requires only mmWave devices to be involved or requires a minimum bandwidth or set of resources to achieve high accuracy). The SF 0930 may also determine a set of sensing devices in neighboring areas (e.g., if the target 0998 is near the edge of a target sensing area or coverage area of a previously selected set of sensing devices) that may need to get involved in sensing of a target.

The SF 0930 may instruct/configure the determined set of sensing devices to initiate or prepare for sensing of a target. This may be done by a set of messages 932 that may be sent/tunneled/forwarded via the AMF 0920 to a set of RAN entities 0910 and/or RAN controllers 0911 and/or UEs 0990 that are part of the determined set of sensing devices, whereby the messages destined for a UE 0990 may be forwarded or repackaged by a RAN entity 0910 to which the UE 0990 is connected. The messages 932 may include sensing signal timing/frequency configuration, target characteristics, such as last known/estimated location, size, shape, velocity, thresholds (e.g., which minimal signal quality required before sensing measurements are performed or transmitted for further processing, minimum/maximum distance from target), identity of a target, and/or the environment (e.g., other sensing devices involved).

The execution of the sensing procedure may also require collecting the user consent preferences. This may involve:

• Sending a request to the UE asking the user for UC confirmation, and/or

• Retrieving the UC preferences from the UDM/UDR, e.g., through the AUSF; and/or

• Sharing the UC preferences with the serving network

And only performing the sensing operation if user consent is granted.

Alternatively or additionally, the SF 0930 may request the RAN 0900 (or other network function (e.g., LMF), not shown in Fig. 13) to determine a set of sensing devices for sensing of a target (i.e., sensing transmitters and/or sensing receivers) that are currently present/located in the target sensing area or that together cover a target sensing area or that are in vicinity of the target 0998, or are in a neighboring area, and/or that meet certain criteria (e.g., required capabilities for sensing, such as mmWave, sufficient bandwidth and/or resources available for sensing). To this end, the SF 0930 may send a message 933 to the RAN 0900 (e.g., to one or more of the RAN controllers 0911) (or other network function), which may include information about the target sensing area or target location information or trajectory information, and/or criteria/requirements/capabilities for sensing. The RAN 0900 (or other network function) may return e.g. in a message 934 the determined set of sensing devices to the SF 0930 for further configuration, or may itself instruct/configure the determined set of sensing devices to initiate or prepare for sensing of a target (e.g., by using information provided by the SF 0930 similar to the information provided in message 932 or pre-configured on the device).

In a next step 915 the determined sensing devices may initiate sensing of the target 0998. This may be based on previous instruction/configuration of the SF 0930 (or the RAN 0900), or the SF 0930 (or the RAN 0900) may send an explicit message 935 to the determined sensing devices to initiate the sensing. Step 915 involves transmitting sensing signals and receiving the sensing signals reflected by the target 0998 and/or sensing messages sent by a UE 0990 attached to/encompassed in the target 0998, and performing the necessary measurements on the (reflected) sensing signals and/or processing the sensing messages containing the measurements made by the UE 0990. The sensing measurements and/or sensing results derived from these measurements may be transmitted by the sensing devices using messages 916/996 to the SF 0930 (or to a RAN entity 0910 or a RAN controller 0911 collecting sensing measurements and/or performing some sensing calculations, or to a central repository from which a sensing service can retrieve these measurements/results) for further processing. The sensing measurements/results may include for each sensing receiver the signal strength and/or quality of the reflected sensing signals (e.g., per sensing signal identifier or beam identifier) or a measure of accuracy of a sensing result for the respective target 0998 (e.g., location accuracy, accuracy of matching target characteristics) or a measure of signal noise/disturbances or timing of sensing signals, or more specific results (such as a frequency (e.g., related to the heart rate of the target), or speed (e.g., related to the speed of a UAV / car target) or location (e.g., related to the location of a car target) or a set of detected objects or count (e.g., related to the number of persons in an area) or other application-related relevant results) and/or the SF 0930 (or the RAN 0900) may derive these quality and/or accuracy and/or noise and/or timing measures based on the received sensing measurements and/or results. Note that also sensing devices that may not receive sensing signals (or with very low quality) may send a sensing measurement report (e.g., indicating/showing no results, or showing signal strength zero for an expected sensing signal). Note that before the information is sent from the RAN 0900 or target 0990, the RAN entities may aggregate or process the measurements in a combined result report.

In a next step 917 the SF 0930 (or the RAN 0900 or by cooperation between the RAN 0900 and a network function (NF)) determines based on the received sensing measurements/results which sensing devices were close to the target and/or performed good measurements of the target and/or which reflected sensing signals were received with good quality (e.g., their timing, characteristics or identifier, based on which the SF 0930 may determine (possibly by requesting/receiving information from the RAN 0900 and/or the RAN controllers 0911 or the respective sensing devices) which sensing transmitter sent those sensing signals). Based on this information, the SF 0930 (or the RAN 0900) may select/change a determined set of sensing devices to be involved in sensing of the target 0998, and instruct/configure them accordingly (using messages 936 similar to messages 932). This helps in reducing the resources used for sensing of the target 0998, by not involving sensing devices that are not able to reach the target 0998 by transmitting sensing signals and/or that are not able to receive the sensing signals (e.g., too far away from the target 0998). The SF 0930 (or the RAN 0900) may select only the best suited/closest sensing devices as a subset of the initially determined set of sensing devices. Furthermore, if the target 0998 is moving, the SF 0930 (or the RAN 0900) may determine or predict (based on the location/trajectory of the target), which additional sensing devices may need to be involved in sensing of the target 0998 based on the direction, speed and/or current location of the target 0998, and/or the received measurements showing a decline or increase of signal strength/quality for a particular sensing device, and/or the location of nearby or neighboring sensing devices (e.g., base stations with overlapping coverage). The SF 0930 (or the RAN 0900) may use this information to instruct/configure these additional devices (e.g., using the messages 936) to prepare them for sensing of the target 0998, in order to assure service continuity. Additionally or alternatively, the SF 0930 (or the RAN 0900) may instruct/configure a sensing device to transmit information about the target 0998 (e.g., "hand-over" information such as target identity, location, sensing signal characteristics/timing) to one of these identified additional devices. This can be seen as two ways of facilitating "hand-over" of sensing between one set of sensing device to another set of sensing devices, i.e., directly by the SF 0930 (or the RAN 0900) or indirectly by letting a sensing device communicate the "hand-over" information to another sensing device.

In a particular example, the SF 0930 or the RAN 0900 (or another network function (e.g., the LMF)) initially selects only a single sensing transmitter and a single sensing receiver (which may be colocated in the same sensing device) that is closest or expected to be closest to the target 0998 or that has the required/best sensing capabilities for an initial sensing of the target 0998 or for performing a radar sweep of the area, to identify and/or determine a (more precise) location of the target 0998 and possible other characteristics of the target 0998. The respective single sensing receiver (and/or transmitter) may send its sensing measurements/results to the SF 0930 (or to a RAN entity 0910 and/or a RAN controller 0911 collecting sensing measurements and/or performing some sensing calculations, or to a central repository from which a sensing service can retrieve these measurements/results). Based on these sensing measurements and/or results, the SF 0930 (or the RAN 0900) may select one or more sensing devices for sensing of the target 0998 that are best suited/located closest to the target 0998. The SF 0930 may send sensing requests towards sensing device capable of providing sensing data of the target 0998 and/or capable of transmitting sensing signals that will be received by one or more sensing receivers (after reflection by the target 0998), and may stop sending sensing requests to a sensing device that is not capable anymore of providing sensing data of the target 0998 and/or capable anymore of transmitting sensing signals that will be received by one or more sensing receivers (after reflection by the target 0998), or send a message towards such sensing device to stop sensing of the target 0998 (e.g., stop transmitting or receiving sensing signals).

In a related embodiment, instead of the SF 0930 or the RAN 0900 performing above determination of a set of sensing devices for sensing the target 0998 and/or instructing/configuring the determined sensing devices (possibly including preparing neighboring sensing devices for service continuity/handover of the sensing of the target 0998), the AF 0950 communicating via the NEF 0940 may perform those actions. To this end, the AF 0950 may be provided (via the NEF 0940) with information about sensing devices and/or capabilities in a certain area, e.g., a requested target sensing area. Also, the AF 0950 may receive the sensing measurements/results (i.e., as indicated above for the SF 0930) to enable it to determine which sensing devices to include in sensing of the target 0998 or prepare for sensing of the target 0998. Additionally or alternatively, the AF 0950 may request a core network function (e.g., the SF 0930) or the RAN 0900 to provide a list of sensing devices based on an estimated location, speed or trajectory of the target 0998, whereby the sensing devices may be identified with a temporary identifier (e.g., issued by the NEF 0940 or another core network function) and/or a relative position to the target 0998 and/or a restricted set of information about the capabilities of the sensing device (e.g., provide information that it is capable of sensing using mmWave, but not which particular frequencies). The AF 0950 may use these temporary identifiers in its selection and/or its configuration messages for sensing. The NEF 0940 or the other core network function can translate the temporary identifier back to the original identifier in order to select or configure the respective sensing device accordingly. As described already, the various embodiments described above may apply to telecommunication applications, including for example wireless sensing applications or in 5G or later generations (6G, ...). They may also be applied to Wifi networks.

HIGH LEVEL USE CASES

Furthermore, the above embodiments can be configured to support multiple use cases, as explained in the following.

In a first use case about optimizing sensing mobility, a home of an elderly person has installed a new 5GS capable of providing communication and sensing capabilities through facilities. The deployed 5GS includes multiple sensing devices, e.g., base stations, providing connectivity and sensing capabilities of vital signs such as heart rate or breathing rate. Since elderly people move through the facilities, it is important to keep track of the vital signs independently of the base station used for sensing. The sensed vital signs are collected in a central server that is automatically monitored for anomalies. If a vital sign anomaly is detected, an alarm can be triggered indicating the vital sign condition as well as the location of the user. In the provided use case, base stations cooperate with each other to ensure efficient sensing handover. In a particular scenario, we consider a user, Robert, who moves through the facilities. Robert is currently sensed by means of base station A and is moving out of the sensing area of base station A and approaching the sensing area of base station B. Base station A and base station B cooperate in such a way that it is ensured that base station B has started a sensing session with Robert before base station A stops its current sensing session.

In this first use case, the following pre-conditions and assumptions apply:

1) The mobile network operator (MNO) operates the 5GS providing sensing services through base station A and base station B.

2) Robert has subscribed to the sensing service.

3) Robert is currently located in the living room and he is currently sensed by means of the base station A.

4) Robert decides to go for a walk to the garden that is covered by the base station B.

In this first use case, the following service flows need to be provided:

1. base station A senses Robert's vital signs and sends the sensed information together with Robert's location to a sensing server.

2. Robert starts moving toward the garden. 3. The sensing signal conditions become better from base station B than for base station

A.

4. Base stations A and B coordinate to handover the responsibility of sensing Robert from base station A to base station B.

5. Base station B senses Robert's vital signs and sends the sensed information together with Robert's location to a sensing server.

6. Base station A stops sensing Robert's vital signs.

In this first use case, the main post-condition is that Robert's vital signs are monitored without interruption independently of Robert's location.

In the first use case, there is a new requirement needed to support the use case, namely, the 5GS shall provide means to handover sensing tasks between different sensing devices.

In the second use case about cooperative sensing, a home of an elderly person has installed a new 5GS capable of providing communication and sensing capabilities through the facilities. The deployed 5GS includes multiple sensing devices, e.g., base stations, providing connectivity and sensing capabilities of vital signs such as heart rate or breathing rate. Since elderly people move through the facilities and facilities may include obstacles that hinder the sensing capabilities, some areas may not be covered by a single base station and multiple base stations may be required to ensure continuous sensing coverage. It is important to keep track of the vital signs independently of which base station can be used for sensing at a given instant of time. In the provided use case, base stations cooperate with each other to ensure efficient cooperative sensing. In a particular scenario, we consider a user, Robert, who is in an area that requires two base stations, base station A and base station B to ensure continuous sensing. Base station A and base station B have been configured to keep track of users in the area and provide sensing services in that area.

In the second use case, the following pre-conditions and assumptions apply:

1) The MNO operates the 5GS providing sensing services through base station A and base station B in a given area, e.g., a large garden.

2) The 5GS is aware of the black sensing spots of the base stations. This information is available to the base stations if they are configured to work in a cooperative manner.

3) Robert has subscribed to the sensing service.

4) Robert is currently located in the garden and he is currently sensed by means of base station A.

5) The 5GS has configured both base station A and base station B to sense the users in the garden, the region of interest.

6) Robert decides to move through the garden. In the second use case, the following service flows need to be provided:

1) Robert starts moving in the garden.

2) At any point of time, when a base station (e.g., A) infers that Robert is about leaving the sensing area of base station (e.g., A) and/or Robert is about entering the sensing area of another base station (e.g., B), the base station (e.g., A) may inform the other base station (e.g., B) about the event and the user's parameters, e.g., the location of Robert, so that the other base station can rapidly start sensing.

3) At any point of time, if Robert is in the sensing area of a base station (e.g., A), base station A senses Robert's vital signs and sends the sensed information together with Robert's location to a sensing server.

4) At any point of time, the sensing server combines the sensed input of multiple sensing devices in a single sensed map.

In this second use case, the main post-condition is that Robert's vital signs are monitored without interruption independently of its location.

In the second use case, there is a new requirement needed to support the use case, namely, the 5G system shall be able to perform simultaneous sensing of a target by means of multiple sensing devices.

In the third use case about optimized communication handover supported by sensing, a smart city has installed a new 5GS capable of providing communication and sensing capabilities. The deployed 5GS includes multiple sensing devices, e.g., base stations, providing connectivity and sensing capabilities to subscribed users. Since users move through the city, it is important to ensure efficient communication handover to be able to deliver the best possible communication link at any point of time. In a particular scenario, we consider a user, Robert, who moves through the city. Robert is currently serviced by means of base station A and is about moving out of the communication area of base station A in a sudden manner due to the spotty coverage in the city environment. The 5GS would benefit of an optimized communication handover supported by sensing to ensure better communication coverage.

In the third use case, the following pre-conditions and assumptions apply:

1) The MNO operates a 5GS providing communication and sensing services through base station A and base station B.

2) Robert has subscribed to the communication and sensing services.

3) The MNO has created an accurate map determining the achievable communication coverage based on the location of a user/UE.

4) Robert is currently located at location A and he is served by means of base station A. 5) Robert decides to move to a different location where the coverage of base station A suddently disappears.

In the third use case, the following service flows need to be provided:

1. Base station A senses that Robert is moving towards a location in which the coverage of base station A suddenly disappears.

2. Base station A may inform base station B about the need of communication handover.

3. Base station A may instruct the UE - based on the sensed location of the UE -- to perform handover when the UE is moving to the area which is better served by base station B.

In the third use case, the main post-condition is that Robert's communication link is featured by the best possible connection independently of its location.

In the third use case, there is a new requirement needed to support the use case, namely, the 5G system shall provide means to optimize communication handover by means of sensing.

To summarize, a wireless communication system with distributed sensing capability has been described, in which wireless devices cooperate with each other to perform a sensing handover by transferring sensing duties from a first wireless device to a second wireless device, so that multiple wireless devices can work together to sense a target in the overall range of interest.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. It can be applied to various types of UEs or terminal devices, such as mobile phone, vital signs monitoring/telemetry devices, smartwatches, detectors, vehicles (for vehicle-to-vehicle (V2V) communication or more general vehicle-to-everything (V2X) communication), V2X devices, Internet of Things (loT) hubs, loT devices, including low-power medical sensors for health monitoring, medical (emergency) diagnosis and treatment devices, for hospital use or first-responder use, virtual reality (VR) headsets, etc.

Moreover, the above embodiments may be implemented in a quasi-distributed deployment where the base station is a central unit (e.g., gNB-CU) and there are two distributed units (e.g., gNB- DUs), one acting as the transmitter device and the other acting as the receiver device, while the central unit may be the entity synchronizing the distributed units.

The base station may be any network access device (such as a base station, Node B (eNB, eNodeB, gNB, gNodeB, ng-eNB, etc.), access point or the like) that provides a geographical service area. Furthermore, at least some of the above embodiments may be implemented to provide network equipment for 5G/6G/xG cellular networks or a new product class of (low-cost/mid-cost) reconfigurable intelligent surfaces to improve coverage, reliability and speed of cellular networks.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. The foregoing description details certain embodiments of the invention. It will be appreciated, however, that no matter how detailed the foregoing appears in the text, the invention may be practiced in many ways, and is therefore not limited to the embodiments disclosed. It should be noted that the use of particular terminology when describing certain features or aspects of the invention should not be taken to imply that the terminology is being re-defined herein to be restricted to include any specific characteristics of the features or aspects of the invention with which that terminology is associated.

Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention, e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc. In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention, e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc. It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B.

The described operations implemented as program code means of a computer program and/or as dedicated hardware of the related network device or function, respectively. The computer program may be stored and/or distributed on a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.