TECHNICAL FIELD

The various example embodiments relate to relates to communica tions.

BACKGROUND

The fifth generation cellular systems (5G) aim to improve the through put by a huge factor (even up to 1000 or more), which provides a multitude of challenges, especially considering the scarcity of spectrum at low frequency bands and the need for supporting a very diverse set of use cases. In order to reach this goal, it is important to exploit the higher frequencies such as millimeter wave frequencies in addition to the more conventional lower frequencies. How ever, the connection between an access node (e.g., a gNodeB, gNB) and a terminal device at millimeter waves is highly sensitive to any kind of blockages due to the use of narrow beams and poor penetration capability of signals with high (car rier) frequency. Multiple beam pair links may be configured and updated between the access node and the terminal device to adapt to the movement of the terminal device and/or changes in the radio environment (e.g., sudden blockage caused by a moving obstruction such as a truck) within a cell and thus to improve reliability of millimeter wave connections. When operating using unlicensed millimeter- wave bands (e.g., 60 GHz band), certain beam pair link(s) may be unavailable for communications at a given time due to interference detected by the spectrum sharing mechanism (such as listen-before-talk). For this reason, it is desirable to provide beam diversity to mitigate temporal unavailability of the certain beam pair link (either due to sudden blockage due to movement, or channel access blockage due to spectrum sharing mechanism).

BRIEF DESCRIPTION

According to an aspect, there is provided the subject matter of the in dependent claims. Embodiments are defined in the dependent claims.

One or more examples of implementations are set forth in more detail in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. According to a first aspect, there is provided a terminal device com prising means for performing: monitoring physical downlink control channel, PDCCH, transmissions according to a first set of rules, wherein the first set of rules comprises rules for performing monitoring over at least two beam pair links, each beam pair link corresponding to a control resource set, CORESET, with a different active transmission configuration indication, TCI, state; receiving, us ing a first CORESET with a first active TCI state from an access node, an indication for limiting monitoring; and limiting, in response to the receiving of the indica tion, monitoring of PDCCH transmissions associated with CORESETs having an ac tive TCI state other than the first active TCI state for a period of time.

According to an example of the first aspect, the indication for limiting monitoring is received as a unicast transmission or as a broadcast transmission.

According to an example of the first aspect, the indication for limiting monitoring is received in a unicast or group-common PDCCH message or in a de modulation reference signal, DMRS, sequence or shift.

According to an example of the first aspect, the means are further con figured to perform: detecting a PDCCH transmission from a first beam pair link corresponding to the first CORESET with the first active TCI state, wherein the de tecting indicates a start of a channel occupancy time, COT.

According to an example of the first aspect, the detecting of the PDCCH transmission from the first beam pair link corresponds to detecting at least one of: a unicast PDCCH transmission; a wideband demodulation reference signal, WB DMRS, denoting the start of the COT; a wake up signal; and a group-common PDCCH transmission.

According to an example of the first aspect, the period of time is de fined as one of: a pre-defined end of the COT; an end of the COT defined in the de tected PDCCH transmission; an end of the COT defined in the indication for limit ing monitoring; a pre-defined end of a downlink portion of the COT; an end of a downlink portion of the COT defined in the detected PDCCH transmission; an end of a downlink portion of the COT defined in the indication for limiting monitoring; a pre-defined number of slots; a pre-defined number of symbols; a number of slots indicated in the detected PDCCH transmission; a number of slots indicated in the indication for limiting monitoring; a number of symbols indicated in the de tected PDCCH transmission; and a number of symbols indicated in the indication for limiting monitoring. According to an example of the first aspect, the period of time is de fined as at least one of: a period expiring at a beginning of the next monitoring oc casion of a search space associated with the first CORESET with the first active TCI state, a period expiring when a timer expires, wherein the timer counts down by slots or symbols from an initial pre-defined value and is started and subse quently reset upon a reception of downlink control information, DC1, of the first active TCI state in the terminal device and a period expiring when a second indi cation for limiting monitoring of PDCCH transmissions associated with CORESETs having an active TCI state other than the second active TCI state for a second pe riod of time is received in the terminal device.

According to a second aspect, there is provided a terminal device com prising means for performing: monitoring physical downlink control channel, PDCCH, transmissions according to a first set of rules, wherein the first set of rules comprises rules for performing monitoring over at least two beam pair links, each beam pair link corresponding to a control resource set, CORESET, with a different active transmission configuration indication, TCI state; detecting a PDCCH transmission from a first beam pair link corresponding to a first CORESET with a first active TCI state, wherein the detecting indicates a start of a COT; and limiting, in response to the detecting, monitoring of PDCCH transmissions associ ated with CORESETs having an active TCI state other than the first active TCI state for a period of time.

According to an example of the second aspect, the means are further configured to perform to perform the limiting of the monitoring of PDCCH trans missions associated with CORESETs having an active TCI state other than the first active TCI state for the period of time based on a configuration of the terminal de vice, the configuration being derived using a Radio Resource Control, RRC, proto col and/or based on contents of a unicast or group-common PDCCH transmission received by the terminal device as said PDCCH transmission.

According to an example of the second aspect, the detecting of the PDCCH transmission from the first beam pair link corresponds to detecting at least one of: a unicast PDCCH transmission; a wideband demodulation reference signal, WB DMRS, denoting the start of the COT; a wake up signal; and a group- common PDCCH transmission.

According to an example of the second aspect, the period of time is de fined as one of: a pre-defined end of the COT; an end of the COT defined in the de tected PDCCH transmission; a pre-defined end of a downlink portion of the COT; an end of a downlink portion of the COT defined in the detected PDCCH transmis sion; a pre-defined number of slots; a pre-defined number of symbols; a number of slots defined in the detected PDCCH transmission; a number of symbols defined in the detected PDCCH transmission; a period expiring at a beginning of the next monitoring occasion of a search space associated with the first CORESET with the first active TCI state; and a period expiring when a timer expires, wherein the timer counts down by slots or symbols from an initial pre-defined value and is started and subsequently reset upon a reception of downlink control information, DCI, of the first active TCI state in the terminal device. According to an example of the second aspect, the limiting of the moni toring of the PDCCH transmissions associated with the CORESETs having an ac tive TCI state other than the first active TCI state for the period of time comprises suspending the monitoring of the PDCCH transmissions associated with the CORESETs having an active TCI state other than the first active TCI state for the period of time.

According to an example of the second aspect, the limiting of the moni toring of the PDCCH transmissions associated with the CORESETs having an ac tive TCI state other than the first active TCI state for the period of time comprises suspending the monitoring of the PDCCH transmissions associated with a CORESET having an active TCI state with the lowest common search space, CSS, index for the period of time.

According to an example of the second aspect, the means are further configured to perform before the monitoring: in response to receiving a first con figuration message comprising at least two search space configurations associ- ated with at least two CORESETs and with at least two different configured and/or active TCI states comprising at least the first active TCI state, configuring the terminal device to perform the monitoring based on said at least two search space configurations.

According to an example of the first or second aspect, the provided ter- minal device is configured to operate in one or more unlicensed millimeter-wave bands.

According to an example of the first or second aspect, the provided ter minal device is a single-panel terminal device configured with multiple active beam pair links but being capable of serving only one beam pair link at a time. According to an example of the first or second aspect, the means com prised in the provided terminal device comprise at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the performance of the terminal device.

According to a third aspect, there is provided an access node compris ing means for performing: transmitting, using a first control resource set, CORESET, with a first active transmission configuration indication, TCI state, to a terminal device, an indication for limiting monitoring of physical downlink con trol channel, PDCCH, transmissions associated with CORESETs having an active TCI state other than the first active TCI state for a period of time.

According to an example of the third aspect, the means are further configured to perform, before the transmitting of the indication: causing configur ing the terminal device to monitor PDCCH transmissions according to a first set of rules by transmitting a first configuration message to the terminal device, wherein the first configuration message comprises at least two search space con figurations associated with at least two CORESETs and with at least two different configured and/or active TCI states comprising at least the first active TCI state for monitoring PDCCH transmissions.

According to an example of the third aspect, the means are further configured to perform: transmitting, before the transmitting of the indication for limiting monitoring, at least one message using a first CORESET with a first active TCI state to the terminal device.

According to an example of the third aspect, the means are further configured to perform: including, in the indication, information on the period of time, wherein the information on the period of time comprises information defin ing the period of time as at least one of a number of slots, a number of symbols, a pre-defined end of a channel occupancy time, COT, and a pre-defined end of a downlink portion of the COT or an indication bit having a pre-defined value for triggering a use of a pre-defined period of time for monitoring of PDCCH trans missions in the terminal device.

According to an example of the third aspect, the means are further configured to perform, before the transmitting of the indication: selecting a pe riod of time configuration for the terminal device dynamically from a pre-defined set of one or more period of time configurations, wherein each period of time con figuration in said pre-defined set defines the period of time as at least one of: a period expiring at an end of a COT, a period expiring at an end of a downlink por tion of a COT, a pre-defined number of slots, a pre-defined number of symbols, a number of slots indicated in the indication for limiting monitoring, a number of symbols indicated in the indication for limiting monitoring, a period expiring at a beginning of the next monitoring occasion of a search space associated with a first CORESET with the first active TCI state, a period expiring when a timer expires, wherein the timer counts down by slots or symbols from an initial pre-defined value and is started and subsequently reset upon a reception of downlink control information, DCI, of the first active TCI state in the terminal device and a period expiring when a second indication for limiting monitoring of PDCCH transmis sions associated with CORESETs having an active TCI state other than the second active TCI state for a second period of time is received in the terminal device; and causing configuring the terminal device to use the selected period of time configu ration by transmitting a second configuration message comprising the selected period of time configuration to the terminal device.

According to an example of the third aspect, the pre-defined set com prises two or more period of time configurations and the selecting of the period of time configuration for the terminal device is based on channel conditions, channel availability and/or a load in a network of the access node.

According to an example of the third aspect, the means comprised in the provided access node comprise at least one processor; and at least one memory including computer program code; the at least one memory and the com puter program code configured to, with the at least one processor, cause the per formance of the terminal device.

According to a fourth aspect, there is provided a method comprising: monitoring physical downlink control channel, PDCCH, transmissions according to a first set of rules, wherein the first set of rules comprises rules for performing monitoring over at least two beam pair links, each beam pair link corresponding to a control resource set, CORESET, with a different active transmission configu ration indication, TCI, state; receiving, using a first CORESET with a first active TCI state from an access node, an indication for limiting monitoring; and limiting, in response to the receiving of the indication, monitoring of PDCCH transmissions associated with CORESETs having an active TCI state other than the first active TCI state for a period of time.

According to a fifth aspect, there is provided a method comprising: monitoring physical downlink control channel, PDCCH, transmissions according to a first set of rules, wherein the first set of rules comprises rules for performing monitoring over at least two beam pair links, each beam pair link corresponding to a control resource set, CORESET, with a different active transmission configu ration indication, TCI, state; detecting a PDCCH transmission from a first beam pair link corresponding to a first CORESET with a first active TCI state, wherein the detecting indicates a start of a COT; and limiting, in response to the detecting, monitoring of PDCCH transmissions associated with CORESETs having an active TCI state other than the first active TCI state for a period of time.

According to a sixth aspect, there is provided a method comprising: transmitting, using a first control resource set, CORESET, with a first active trans mission configuration indication, TCI, state, to a terminal device, an indication for limiting monitoring of physical downlink control channel, PDCCH, transmissions associated with CORESETs having an active TCI state other than the first active TCI state for a period of time.

According to a seventh aspect, there is provided a computer program comprising instructions stored thereon for performing at least the following: monitoring physical downlink control channel, PDCCH, transmissions according to a first set of rules, wherein the first set of rules comprises rules for performing monitoring over at least two beam pair links, each beam pair link corresponding to a control resource set, CORESET, with a different active transmission configu ration indication, TCI, state; receiving, using a first CORESET with a first active TCI state from an access node, an indication for limiting monitoring; and limiting, in response to the receiving of the indication, monitoring of PDCCH transmissions associated with CORESETs having an active TCI state other than the first active TCI state for a period of time.

According to an eighth aspect, there is provided a computer program comprising instructions stored thereon for performing at least the following: monitoring physical downlink control channel, PDCCH, transmissions according to a first set of rules, wherein the first set of rules comprises rules for performing monitoring over at least two beam pair links, each beam pair link corresponding to a control resource set, CORESET, with a different active transmission configu- ration indication, TCI, state; detecting a PDCCH transmission from a first beam pair link corresponding to a first CORESET with a first active TCI state, wherein the detecting indicates a start of a channel occupancy time, COT; and limiting, in response to the detecting, monitoring of PDCCH transmissions associated with CORESETs having an active TCI state other than the first active TCI state for a pe- riod oftime. According to a ninth aspect, there is provided a computer program comprising instructions stored thereon for performing at least the following: transmitting, using a first control resource set, CORESET, with a first active trans mission configuration indication, TCI, state, to a terminal device, an indication for limiting monitoring of PDCCH transmissions associated with CORESETs having an active TCI state other than the first active TCI state for a period of time.

According to an tenth aspect, there is provided an electromagnetic sig nal using a first configuration resource set, CORESET, associated with a first ac tive transmission configuration indication, TCI, state, and carrying computer- readable data comprising an indication indicating whether or not to limit moni toring of physical downlink control channel, PDCCH, transmissions associated with CORESETs having an active TCI state other than the first active TCI state for a period of time.

BRIEF DESCRIPTION OF DRAWINGS

In the following, exemplary embodiments will be described with refer ence to the attached drawings, in which

Figure 1 illustrates a wireless communication scenario to which em bodiments may be applied;

Figures 2A, 2B and 3 illustrate processes according to embodiments; and

Figure 4 illustrates exemplary PDCCH monitoring operation according to an embodiment;

Figures 5 and 6 illustrate apparatuses according to embodiments.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

The following embodiments are exemplary. Although the specification may refer to "an", "one", or "some" embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

In the following, different exemplifying embodiments will be described using, as an example of an access architecture to which the embodiments may be applied, a radio access architecture based on long term evolution advanced (LTE Advanced, LTE-A) or new radio (NR, 5G), without restricting the embodiments to such an architecture, however. It is obvious for a person skilled in the art that the embodiments may also be applied to other kinds of communications networks hav ing suitable means by adjusting parameters and procedures appropriately. Some examples of other options for suitable systems are the universal mobile telecom munications system (UMTS) radio access network (UTRAN or E-UTRAN), longterm evolution (LTE, the same as E-UTRA), wireless local area network (WLAN or WiFi), worldwide interoperability for microwave access (WiMAX), Bluetooth®, personal communications services (PCS), ZigBee®, wideband code division multiple access (WCDMA), systems using ultra-wideband (UWB) technology, sensor networks, mo bile ad-hoc networks (MANETs) and Internet Protocol multimedia subsystems (IMS) or any combination thereof.

Figure 1 depicts examples of simplified system architectures only show ing some elements and functional entities, all being logical units, whose implemen tation may differ from what is shown. The connections shown in Figure 1 are logical connections; the actual physical connections may be different. It is apparent to a person skilled in the art that the system typically comprises also other functions and structures than those shown in Figure 1.

The embodiments are not, however, restricted to the system given as an example but a person skilled in the art may apply the solution to other communi cation systems provided with necessary properties.

The example of Figure 1 shows a part of an exemplifying radio access network.

Figure 1 shows user devices 100 and 102 configured to be in a wireless connection on one or more communication channels in a cell with an access node (such as (e/g)NodeB) 104 providing the cell. The physical link from a user device to a (e/g)NodeB is called uplink or reverse link and the physical link from the (e/g)NodeB to the user device is called downlink or forward link. It should be ap preciated that (e/g)NodeBs or their functionalities may be implemented by using any node, host, server or access point etc. entity suitable for such a usage.

A communications system typically comprises more than one (e/g)NodeB in which case the (e/g)NodeBs may also be configured to communicate with one another over links, wired or wireless, designed for the purpose. These links may be used for signaling purposes. The (e/g)NodeB is a computing device configured to control the radio resources of communication system it is coupled to. The NodeB may also be referred to as a base station, an access point or any other type of interfacing device including a relay station capable of operating in a wire less environment. As an example of the relay station, the gNB functionalities may be carried out by DU part of the 1AB (integrated access and backhaul) node. The (e/g)NodeB includes or is coupled to transceivers. From the transceivers of the (e/g)NodeB, a connection is provided to an antenna unit that establishes bi-direc tional radio links to user devices. The antenna unit may comprise a plurality of an tennas or antenna elements. The (e/g)NodeB is further connected to core network 110 (CN or next generation core NGC). Depending on the system, the counterpart on the CN side can be a serving gateway (S-GW, routing and forwarding user data packets), packet data network gateway (P-GW), for providing connectivity of user devices (UEs) to external packet data networks, or mobile management entity (MME), etc.

The user device (also called UE, user equipment, user terminal, terminal device, etc.) illustrates one type of an apparatus to which resources on the air in terface are allocated and assigned, and thus any feature described herein with a user device may be implemented with a corresponding apparatus, such as a relay node. An example of such a relay node is a so-called 1AB node, where UE function alities are carried out by MT (Mobile Termination) part of the 1AB node. The MT part may be called also as 1AB-UE.

The user device typically refers to a portable computing device that in cludes wireless mobile communication devices operating with or without a sub scriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (mobile phone), smartphone, personal digital as sistant (PDA), handset, device using a wireless modem (alarm or measurement de vice, etc.), laptop and/or touch screen computer, tablet, game console, notebook, and multimedia device. It should be appreciated that a user device may also be a nearly exclusive uplink only device, of which an example is a camera or video cam era loading images or video clips to a network. A user device may also be a device having capability to operate in Internet of Things (loT) network which is a scenario in which objects are provided with the ability to transfer data over a network with out requiring human-to-human or human-to-computer interaction. The user de vice (or in some embodiments a relay node) is configured to perform one or more of user equipment functionalities. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal or user equip ment (UE) just to mention but a few names or apparatuses. Various techniques described herein may also be applied to a cyber physical system (CPS) (a system of collaborating computational elements control ling physical entities). CPS may enable the implementation and exploitation of mas sive amounts of interconnected 1CT devices (sensors, actuators, processors micro controllers, etc.) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals.

It should be understood that, in Figure 1, user devices are depicted to include 2 antennas only for the sake of clarity. The number of reception and/or transmission antennas may naturally vary according to a current implementation.

Additionally, although the apparatuses have been depicted as single en tities, different units, processors and/or memory units (not all shown in Figure 1) may be implemented.

5G enables using multiple input - multiple output (M1MO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and employ ing a variety of radio technologies depending on service needs, use cases and/or spectrum available. 5G mobile communications supports a wide range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine type applications, including ve hicular safety, different sensors and real-time control. 5G is expected to have mul tiple radio interfaces, namely below 6GHz, cmWave and mmWave, and also being integratable with existing legacy radio access technologies, such as the LTE. Inte gration with the LTE may be implemented, at least in the early phase, as a system, where macro coverage is provided by the LTE and 5G radio interface access comes from small cells by aggregation to the LTE. In other words, 5G is planned to support both inter- RAT (Radio Access Technology) operability (such as LTE-5G) and inter- R1 operability (inter-radio interface operability, such as below 6GHz - cmWave, be low 6GHz - cmWave - mmWave). One of the concepts considered to be used in 5G networks is network slicing in which multiple independent and dedicated virtual sub-networks (network instances) may be created within the same infrastructure to run services that have different requirements on latency, reliability, throughput and mobility. The current architecture in LTE networks is fully distributed in the ra dio and fully centralized in the core network. The low latency applications and ser vices in 5G require to bring the content close to the radio which leads to local break out and multi-access edge computing (MEC). 5G enables analytics and knowledge generation to occur at the source of the data. This approach requires leveraging resources that may not be continuously connected to a network such as laptops, smartphones, tablets and sensors. MEC provides a distributed computing environ ment for application and service hosting. It also has the ability to store and process content in close proximity to cellular subscribers for faster response time. Edge computing covers a wide range of technologies such as wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer- to-peer ad hoc networking and processing also classifiable as local cloud/fog com puting and grid/mesh computing, dew computing, mobile edge computing, cloud let, distributed data storage and retrieval, autonomic self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and/or latency critical), critical communications (autono mous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications).

The communication system is also able to communicate with other net works, such as a public switched telephone network or the Internet 112, or utilize services provided by them. The communication network may also be able to sup port the usage of cloud services, for example at least part of core network opera tions may be carried out as a cloud service (this is depicted in Figure 1 by "cloud" 114). The communication system may also comprise a central control entity, or a like, providing facilities for networks of different operators to cooperate for exam ple in spectrum sharing.

Edge cloud may be brought into radio access network (RAN) by utilizing network function virtualization (NVF) and software defined networking (SDN). Us ing edge cloud may mean access node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head or base sta tion comprising radio parts. It is also possible that node operations will be distrib uted among a plurality of servers, nodes or hosts. Application of cloudRAN archi tecture enables RAN real time functions being carried out at the RAN side (in a dis tributed unit, DU 104) and non-real time functions being carried out in a central ized manner (in a centralized unit, CU 108). It should also be understood that the distribution of labor between core network operations and base station operations may differ from that of the LTE or even be non-existent. Some other technology advancements probably to be used are Big Data and all-IP, which may change the way networks are being constructed and managed. 5G (or new radio, NR) networks are being designed to support mul tiple hierarchies, where MEC servers can be placed between the core and the base station or nodeB (gNB). It should be appreciated that MEC can be applied in 4G networks as well.

5G may also utilize satellite communication to enhance or complement the coverage of 5G service, for example by providing backhauling. Possible use cases are providing service continuity for machine-to-machine (M2M) or Internet of Things (IoT) devices or for passengers on board of vehicles, or ensuring service availability for critical communications, and future railway/maritime /aeronautical communications. Satellite communication may utilize geostationary earth orbit (GEO) satellite systems, but also low earth orbit (LEO) satellite systems, in partic ular mega-constellations (systems in which hundreds of (nano) satellites are de ployed). Each satellite 106 in the mega-constellation may cover several satellite- enabled network entities that create on-ground cells. The on-ground cells may be created through an on-ground relay node 104 or by a gNB located on-ground or in a satellite.

It is obvious for a person skilled in the art that the depicted system is only an example of a part of a radio access system and in practice, the system may comprise a plurality of access nodes such as (e/g)NodeBs, the user device may have an access to a plurality of radio cells and the system may comprise also other ap paratuses, such as relay (or IAB) nodes or other network elements, etc. At least one of the (e/g)NodeBs or may be a Home(e/g)nodeB. Additionally, in a geographical area of a radio communication system a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided. Radio cells may be macro cells (or umbrella cells) which are large cells, usually having a diameter of up to tens of kilometers, or smaller cells such as micro-, femto- or picocells. The (e/g)NodeBs of Figure 1 may provide any kind of these cells. A cellular radio system may be imple mented as a multilayer network including several kinds of cells. Typically, in mul tilayer networks, one access node provides one kind of a cell or cells, and thus a plurality of (e/g)NodeBs are required to provide such a network structure.

For fulfilling the need for improving the deployment and performance of communication systems, the concept of "plug-and-play" (e/g)NodeBs has been introduced. Typically, a network which is able to use "plug-and-play" (e/g)Node Bs, includes, in addition to Home (e/g)NodeBs (H(e/g)nodeBs), a home node B gate way, or HNB-GW (not shown in Figure 1). A HNB Gateway (HNB-GW), which is typ ically installed within an operator’s network may aggregate traffic from a large number of HNBs back to a core network.

At least some of the embodiments to be discussed may specifically be targeting operation in unlicensed spectrum at millimeter waves. Operation in un licensed spectrum is regulated by certain channel access rules with the goal of en abling fair spectrum use among different RATs/networks or even among different (access) nodes of the same network on the same shared unlicensed spectrum. The rules may require, e.g., the use of listen-before-talk (LBT) -type channel access and/or the use of other channel sensing mechanisms such as detect-and-avoid (DAA) mechanism. Specifically in beam-based operation, said LBT operation may be performed on the intended transmit direction, i.e., the transmitter may per- form channel sensing using the beam it intends to use for the scheduled or planned transmission. In fact, a device with analog beamforming is not, by defini tion, capable of performing omnidirectional LBT. Thus, in the following scenarios of interest it is assumed that LBT or other channel sensing is performed per beam and that there exists also an LBT or channel sensing process per beam. One of the parameters used for limiting channel access in unlicensed spectrum relevant for the embodiments is Channel Occupancy Time (COT) which defines a time interval when the device occupies the channel. Typically, the COT is initiated by the LBT procedure. The maximum duration of the COT may vary de pending on the scenario and configuration. At least some of the embodiments may be targeting specifically the 60

GHz band which is an unlicensed band in most countries. The 60 GHz band may be understood, in the context of this application, as a frequency band comprising 60 GHz (or at least one frequencies in close vicinity of 60 GHz). Specifically, the 60 GHz band may be defined to correspond to a 60 GHz band as defined in any coun- try of the world (or European Union). For example, the 60 GHz band may corre spond to any of 57-71 GHz, 57-66 GHz, 57-64 GHz, 57.1-63.9 GHz and 59.4-62.9 GHz.

Other unlicensed millimeter-wave bands (i.e., bands other than the 60 GHz band) may be targeted in other embodiments. Said other unlicensed millime- ter-wave bands may comprise current or future unlicensed millimeter-wave bands. For example, said other unlicensed millimeter-wave bands may comprise FR2 band (24-52.6 GHz as defined in current NR) and/or a future extension to 52.6 - 114 GHz (to be covered in R17/18).

One suggested feature of the future 5G communications systems is the so-called 5G New Radio. 5G New Radio refers to a new global 5G standard for an orthogonal frequency-division multiplexing (OFDM) -based air interface designed to fit the more stringent requirements of the 5G systems (for example, providing different types of services to a huge number of different types of devices operat ing over a wide frequency spectrum). The 5G New Radio shall be able to allow network deployment with minimized manual efforts and as automated self-con- figuration as possible.

New Radio (or specifically Release-15 of New Radio) defines four dif ferent QCL (quasi co-location) types, between two reference signals (RS) or a ref erence signal and a channel (including physical data and control channels). Quasi co-location may be defined so that two antenna ports are said to be quasi co-lo- cated if some properties of the channel over which a symbol on one antenna port is conveyed can be inferred from the channel over which a symbol on the other antenna port is conveyed. An antenna port is, here, a logical concept defined such that the channel over which a symbol on the antenna port is conveyed can be in ferred from the channel over which another symbol on the same antenna port is conveyed. Each antenna port corresponds to a specific (characteristic) channel (i.e., symbols transmitted over a given antenna port are subject to the same prop agation conditions) and is associated with its own reference signal. There is one resource grid per antenna port.

In other words, each transmitted reference signal is subject to specific (characteristic) propagation conditions between a transmitter and a receiver and reference signals that are sharing the same or similar propagation conditions are considered quasi collocated. Each reference signal may have (or be associated with) a source reference signal. However, for example, SSB (Synchronization Sig nal Block referring more specifically to a Synchronization/ Physical Broadcast Channel block) does not have a source reference signal.

The QCL types are defined as shown in the table below.

To give an example, a PDCCH from an access node and a SSB are quasi collocated if it is determined that they both encounter similar channel conditions (or properties). Said channel conditions correspond to the QCL parameter sets as defined on the table above. When two reference signals or channels are of the same QCL-TypeD, it is assumed that the same analog beam-pair is utilized for both reception and transmission.

A Transmission Configuration Indicator (TCI) states are state configu rations within the higher layer parameter PDSCHConflg. Each TCl-State contains parameters for configuring a quasi co-location relationship between one or two downlink reference signals and the DMRS ports of the PDSCH, the DMRS port of PDCCH or the CS1-RS port(s) of a CS1-RS resource. TCI States are dynamically sent over in a DC1 (Downlink Control Information) message which includes configura tions such as QCL-relationships between the DL RSs in one CS1-RS (Channel State Information Reference Signal) set and the PDSCH DMRS (Physical Downlink Shared CHannel DeModulation Reference Signal) ports. A terminal device may be configured with a list of up to M TCl-States to decode a PDSCH according to a de tected Physical Downlink Control CHannel (PDCCH) with DC1 intended for the ter minal device and a given serving cell. Here, M is an integer which depends on the terminal device capability ( maxNumberActiveTCI-PerBWP).The embodiments to be discussed below may specifically employ single-panel terminal devices. A sin gle-panel terminal device is a terminal device comprising a single antenna panel (i.e., a single, typically flat antenna array) which in turn comprises a plurality of antenna elements. Consequently, a single-panel terminal device is capable of transmitting and receiving, respectively, via only said one antenna panel (or spe- cifically via an analog beam provided by said antenna panel in QCL-TypeD) at a given time and/or have only one baseband and thus need to decide a panel/beam from which to receive or transmit on. In at least some of the embodiments to be discussed below (e.g., ones employing 60 GHz band), it may be assumed that a terminal device is not capable of digital beamforming (i.e., not being able to use more than one beam at a given time). Moreover, it may be assumed that (single panel) terminal devices according to embodiments (or at least some of them) are capable of handling only one active TCI state at a given time.

In the embodiments to be discussed below, each terminal device may be configured with one or more CORESETs (COntrol REsource SETs). A CORESET may be defined as a set of physical resources (i.e., a specific area on NR Downlink Resource Grid) and a set of parameters that is used to carry the PDCCH and DC1. Specifically, a CORESET may be defined as a resource allocation unit made up of resource element groups (REGs) in frequency domain and 1 or 2 or 3 OFDM sym- bols in time domain. Each REG may be made of a resource block (RB) comprising 12 resource elements (RE). Each of said one or more CORESETs may comprise a single TCI state or multiple TCI states. Only one TCI state is active at a given time for a given CORESET. An access node may switch the active TCI state of the termi nal device by a transmitting MAC-CE (Medium Access Control - Control Element) command to the terminal device.

To deal with limitations of single-panel terminal devices, New Radio (Release 15) defines the following procedure for licensed bands. A terminal de vice, initially, follows the latest active TCI state activated for the latest downlink CORESET. In response to two CORESETs with different active TCI states becoming overlapped in time, the terminal device (capable of one active state) selects the TCI state of the CORESET with the lowest CSS (Common Search Space) index ofthe cell with the lowest serving cell ID.

Connection between an access node and a terminal device is sensitive to any kind of blockages at millimeter wave frequencies due to use of narrow beams and poor penetration capability of a signal at high carrier frequencies. Mul tiple beam pair links may be configured and updated between an access node and a terminal device to adapt to the movement of the terminal device within a cell. A beam pair link may be defined as a pair comprising a transmit beam at the access node and receive beam at the terminal device in downlink and as a pair compris- ing a transmit beam at the terminal device and a receive beam at the access node in uplink. Furthermore, when operating at 60 GHz scenario, certain beam pair link(s) may be unavailable for communications based on interference detected by the spectrum sharing mechanism (such as to LBT). For these reasons, it is desira ble to provide beam diversity to mitigate temporal unavailability of the certain beam pair link (either due to sudden blockage due to movement, or channel ac cess blockage due to spectrum sharing mechanism).

In the case of unlicensed operation (especially at the 60 GHz band) and single-panel terminal devices, the aforementioned licensed TCI state operational behavior is not ideal when multiple CORESETs with different TCI states are con- figured in the terminal device for beam diversity purpose. A terminal device which had previously detected a first COT with a first active TCI state would still need to monitor for CORESETs with a second active TCI state during said first COT according to the behavior described above. However, this is clearly ineffi cient operation in this case, because during the monitoring for the CORESETs with the second active TCI state, a terminal device cannot be served in the ongoing first COT applying the first active TCI state. Further, if multiple CORESETs with differ ent active TCI states would be overlapping, a terminal device would even need to drop monitoring for a CORESET with the first (active) TCI state corresponding to the first COT if the CORESET with the second active TCI state had a higher CSS in dex. This type of behavior is clearly not desirable. Finally, during the first COT, a multi-panel access node may acquire a second COT for the second active TCI state, which may correspond to a better beam for the terminal device, the access node may want to switch the terminal device to the second COT of the second active TCI state.

Figure 2A illustrates a process according to embodiments for perform ing PDCCH monitoring in an efficient manner. The illustrated process may be per formed by a terminal device or more specifically either of the terminal devices 100, 102 of Figure 1. Specifically, said terminal device maybe a single-panel ter minal device, that is, the terminal device may be configured with multiple active beam pair links, but it may be capable of serving only one beam pair link at a time. The terminal device may be configured to operate at millimeter wave frequencies. Moreover, said terminal device may be configured to operate using unlicensed spectrum (e.g., at a 60 GHz band) though in other embodiments licensed spec trum may also be used.

Referring to Figure 2A, the terminal device monitors, in block 201, PDCCH transmissions according to a first set of rules. Specifically, the first set of rules comprises rules for performing monitoring over at least two beam pair links. Each beam pair link corresponds to a CORESET with a different active TCI state. In other words, the terminal device is assumed to be configured to employ at least two beam pair links corresponding to at least two CORESETS with differ ent TCI states (or specifically with different active TCI states). Each CORESET may have multiple TCI states configured, but only one of them may be active at a given time for a given CORESET. The first set of rules may also comprise predefined search space priorities.

The terminal device receives, in block 202, using a first CORESET with a first active TCI state (via a wireless communications link) from an access node, an indication for limiting monitoring. Said first CORESET with the first active TCI state is associated with one of said at least two beam pair links. For example, the indication may be received, in block 202, in the content of the unicast or group- common PDCCH or content carried by the DMRS sequence or shifts. Further de tails regarding the reception of the indication for limiting monitoring is provided in relation to further embodiments.

In response to the receiving of the indication in block 202, the terminal device limits, in block 203, monitoring of PDCCH transmissions associated with CORESETs having a TCI state other than the first active TCI state for a period of time. In other words, the terminal device monitors in a normal manner only PDCCH transmissions associated with the first active TCI state during said period of time. The period of time may be a pre-defined period of time or a period of time determined dynamically by the terminal device, possibly based on information re ceived in the indication for limiting monitoring. The limiting of the monitoring in block 203 may comprise, specifically, suspending the monitoring of the PDCCH transmissions associated with the CORESETs having an active TCI state other than the first active TCI state for said period of time. In other embodiments, other limiting behavior may be, additionally or alternatively, applied. For example, the limiting in block 203 may comprise suspending the monitoring of the PDCCH transmissions associated with a CORESET having an active TCI state with the low est CSS index.

For example, if the terminal device is configured to perform monitor ing over first, second and third beam pair links corresponding to first, second and third CORESETs with first, second and third active TCI states, respectively, the terminal device may limit or suspend monitoring of PDCCH transmissions related to the second and third beam pair link corresponding to the second and third CORESETs with the second and third active TCI states while continuing the moni toring of PDCCH transmissions related to the first beam pair link corresponding to the first CORESET with the first active TCI state without change. After said pe riod of time has passed, the terminal device continues the monitoring of PDCCH transmissions from each of said at least two beam pair links (as indicated by the arrow connection block 203, to block 201).

Figure 2B illustrates a process according to embodiments for perform ing signaling to a terminal device so as to enable or trigger the terminal device to perform PDCCH monitoring in an efficient manner. The illustrated process may be performed by an access node (e.g., a gNB or an eNB) or more specifically by the access node 104 of Figure 1. The access node may be configured to operate at mil limeter wave frequencies. Moreover, said access node may be configured to oper ate using unlicensed spectrum (e.g., at a 60 GHz band) though in other embodi ments licensed spectrum may also be used. The process of Figure 2B carried out by the access node may corresponds to the process of Figure 2A carried out by a terminal device, that is, said processes may be carried out in parallel by said two entities.

It is assumed, in Figure 2B, that a terminal device connected to the ac cess node via a wireless communication link is, initially, configured to monitor PDCCH transmissions according to a first set of rules. Similar to as defined in rela tion to Figure 2A, the first set of rules comprises rules for performing monitoring over at least two beam pair links, each beam pair link corresponding to a CORESET with a different (active) TCI state. The configuring of the terminal de vice may have been carried out previously by the access node performing the pro cess of Figure 2B or some other access node (or other network node) by wire lessly transmitting a configuration message to the terminal device (see Figure 3) or by the terminal device itself.

The access node transmits, in block 211, using a first CORESET with a first active TCI state, an indication for limiting monitoring to the terminal device. Specifically, the indication in block 211 may be for limiting (or suspending) moni toring of PDCCH transmissions associated with CORESETs having an active TCI state other than the first active TCI state for a period of time. The transmission in block 211 may be a broadcast or a unicast transmission. Specifically, the indica tion may be transmitted, in block 211, in the content of the unicast or group-com mon PDCCH or content carried by the DMRS sequence or shifts.

In some embodiments, the access node may include, in the indication transmitted in block 211, information on said period of time. The access node (as opposed to the terminal device itself) may define the period of time (i.e., the dura tion of the period of time and/or the beginning of the period of time and/or the end of the period of time) in said information on the period of time. The period of time may be, for example, indicated as a number of slots or symbols. Alterna tively, the period of time may be indicated as a pre-defined end of a COT (i.e., a pre-defined end of channel occupancy) and a pre-defined end of a downlink por tion of the COT (i.e., a pre-defined end of channel occupancy for dowinlink).

In other embodiments, the information on said period of time may comprise a flag or an indication bit indicating to the terminal device whether or not to use a certain pre-defined period of time configuration (e.g., defining the pe riod of time as an end of the COT, as an end of a downlink portion of the COT or as a pre-defined number of slots or symbols) in limiting the PDCCH monitoring. In such embodiments, the terminal device may be preconfigured with said pre-de fined period of time configuration (e.g., as will be discussed in relation to Figure 3). Said flag or indication bit may act simultaneously also as an indicator on whether or not to limit the monitoring of PDCCH transmissions. Alternatively, dif ferent values of said flag or indication bit may correspond to different periods of time (preconfigured to the terminal device). This latter option of using a simple flag or indication bit has the advantage of low signalling overhead. Further op tions for the definition of the period of time (or the period of time configuration) according to embodiments is provided in relation to Figure 3 (specifically, in rela tion to block 304).

Figure 3 illustrates signaling between an access node and a terminal device according to embodiments for performing PDCCH monitoring in the termi nal device in an efficient manner. The illustrated processes corresponds for the most part to Figures 2A and 2B. Thus, the definitions for the terminal device and access node provided in relation to Figures 2A and 2B (unless otherwise stated).

In contrast to Figures 2A and 2B, Figure 3 illustrates (in elements 301 to 305) also the processes of configuring the terminal device for normal monitor ing operation (i.e., non-suspended operation) and for suspended monitoring op eration.

First, the access node causes, in elements 301, 302, 303, configuring a terminal device to monitor PDCCH transmissions according to a first set of rules. As defined also in relation to Figure 2, the first set of rules comprises rules for performing monitoring over at least two beam pair links, each beam pair link cor responding to a CORESET with a different active TCI state. Specifically, the caus ing configuring may comprise transmitting, by the access node in message 301, a first configuration message to the terminal device, receiving, in the terminal de vice in block 302, the first configuration message and configuring, in block 303, the terminal device according to the first configuration message. The first configu ration message (i.e., message 301) may comprise at least two search space config urations associated with at least two CORESETs and at least two different active (and/or configured) TCI states (comprising a first active TCI state and one or more other TCI states). The first configuration message may be transmitted using RRC (Radio Resource Control) signaling. Each search space configuration defines at least one search space. Therefore, in response to receiving the first configura tion message in block 302, the terminal device configures, in block 303, itself to perform the PDCCH monitoring based on said at least two search space configura tions.

It is assumed here that PDCCH monitoring occasions for at least two search spaces (defined in said at least two search spaces, respectively) associated with CORESETs with different active TCI states overlap at least partially in time. It is further assumed that the terminal device is capable of performing PDCCH moni toring at a given time only based on search spaces associated with CORESETs hav ing the same active TCI state.

Second, the access node causes, in elements 304, 305, 306, 307, config uring a terminal device to employ a particular period of time or period of time configuration in limiting the monitoring of the PDCCH transmissions. The access node selects, in block 304, a period of time configuration for the terminal device dynamically from a pre-defined set of one or more period of time configurations. Each period of time configuration in said pre-defined set may define the period of time as a pre-defined period of time or as a period expiring in response to certain criteria being met (i.e., a period duration of which depends, e.g., on network be havior). Specifically, each period of time configuration in said pre-defined set may define the period of time as at least one of:

• a period expiring at an end of the COT (i.e., at an end of the channel occupancy),

• a period expiring at an end of a downlink portion of the COT,

• a pre-defined number of slots,

• a pre-defined number of symbols,

• a number of slots to be indicated separately in an indication for limiting monitoring or in another PDCCH message,

• a number of symbols to be indicated separately in an indication for limiting monitoring or in another PDCCH message,

• a period expiring at a beginning of the next monitoring occasion of a search space associated with a first CORESET with the first active TCI state,

• a period expiring when a timer expires, wherein the timer counts down by slots or symbols (from an initial pre-defined value) and is started and subsequently reset upon a reception of DCI of the first active TCI state in the terminal device and • a period expiring when a second indication for limiting monitoring of PDCCH transmissions associated with CORESETs having an active TCI state other than the second active TCI state for a second period of time is received in the terminal device.

In some embodiments, said pre-defined set of one or more period of time configu rations may comprise multiple configurations corresponding to different pre-de- fined number of slots and/or multiple configurations corresponding to different pre-defined number of symbols. While said pre-defined set of one or more period of time configurations may consists, in some cases, of only a single period of time configuration, providing multiple options (i.e., a pre-defined set of two or more period of time configuration) provides the additional benefit of enabling the ac cess node to optimize performance based on channel conditions, channel availa bility and/or a load in a network of the access node.

In some embodiments, a period of time configuration may comprise a pre-defined period of time and one or more periods expiring in response to cer tain criteria being met (e.g., one or more of any of such options listed above).

After the selecting in block 304, the access node transmits, in message 305, a second configuration message to the terminal device. The second configu ration message comprises at least the selected period of time configuration. In re sponse to receiving, in block 306, the second configuration message, the terminal device configures, in block 307, itself according to the selected period of time con figuration.

While above it was assumed that the access node selects a single pe riod of time configuration and configures the terminal device to use said single period of time configuration, in some other embodiments, the access node may select two or more period of time configurations defining multiple periods of time (in element 304) and configure the terminal device to use said two or more pe riod of time configurations (in elements 305 to 307). In such embodiments, the terminal device may be able to select the period of time dynamically, for example, based on a received indication for limiting monitoring and information comprised therein (as will be discussed below).

In some embodiments, only one or none of the configurations defined in elements 301 to 303 and elements 304 to 307 may be carried out. In some other embodiments, both of the configurations defined in elements 301 to 303 and elements 304 to 307 may be carried out but in a different order or in parallel with each other. In some embodiments, the terminal device may be configured ac cording to any of the configurations described above by another network node (e.g., by another access node).

After the terminal device has been configured in elements 301 to 307, the terminal device monitors, in block 308, PDCCH transmissions according to the first set of rules, where the first set of rules comprises rules for performing moni toring over at least two beam pair links and based on said at least two search space configurations. Said at least two beam pair links and said at least two search space configurations are associated with at least two CORESETs and at least two different active TCI states. The monitoring in block 308 may, specifi cally, comprise searching for a COT start or for a COT presence based on each of said at least two search space configurations.

The access node transmits, in message 309, at least one message to the terminal device using a first CORESET with a first active TCI state. Said at least one message serves (in view of the illustrated process) to indicate to the terminal device that a PDCCH transmission (i.e., any PDCCH transmission) using a first CORESET with the first active TCI state has commenced. In some embodiments, said at least one message (i.e., message 309) may comprise information on one or more of a start of the COT (i.e., a start of the channel occupancy), an end of the COT (i.e., an end of the channel occupancy), a structure of the COT and a presence of the COT. Said at least one message may be, for example, at least one of unicast PDCCH transmission (or a unicast downlink control information, DCI), a wide band demodulation reference signal (WB DMRS) denoting the start of the COT, a wake up signal and a group-common PDCCH transmission. The transmission in message 309 may be a unicast or broadcast transmission.

When the access node transmits message 309, the terminal device is monitoring PDCCH according to block 308. Consequently, the terminal device re ceives, in block 310, the at least one message transmitted from the access node based on a search space associated with the first CORESET with the first active TCI state. In other words, the terminal device detects, in block 310, a PDCCH transmission from a first beam pair link corresponding to the first CORESET with the first active TCI state. Based on the receiving (or detecting) in block 310, the terminal device determines, in block 311, that a COT (and thus transmission) has started according to one or more search space(s) associated with CORESET(s) with the first active TCI state. In other words, the receiving in block 310, detects, in block 311, a start of the COT (based on the receiving of the message 309 in block 310).

Subsequently, the access node transmits, in message 312, an indication for limiting monitoring to the terminal device using the first CORESET with the first active TCI state, similar to as described in relation to Figure 2B. As described in detail in relation to Figure 2B, the indication in message 312 may comprise in formation on a period of time (e.g., an indication bit or information on a number of slots or symbols) to be used in limiting the monitoring of PDCCH transmissions. In some embodiments, messages 309, 312 may correspond to a single message. In some embodiments, the information on the period of time may comprise infor mation on one or more of the start of the COT, the end of the COT, the end of a downlink portion of the COT, the structure of the COT and a presence of the COT. Any of the listed options may be given, e.g., in slots.

The terminal device receives, in block 313, the indication for limiting monitoring (and optionally other control data) from the access node based on a search space associated with the first CORESET with the first active TCI state. Based on the received indication, the terminal device is able to determine PDCCH monitoring behavior for said at least two search space configurations associated with CORESET(s) with the other active TCI states for a period of time. Specifically, the terminal device, first, determines, in block 314, a period of time during which the PDCCH monitoring is to be limited. The determining in block 314 may be based on the period of time configuration or configurations of the terminal device (configured in elements 304, 305, 306, 307) and optionally the indication for lim iting monitoring.

The determining in block 314 may be carried out in multiple different ways depending, for example, on period of time configuration of the terminal de vice (e.g., as configured by the access node in elements 304, 305, 306, 307) and what information is received (or expected to be received) in block 313.

In some embodiments, the terminal device may be configured to only use a single period of time which is defined as at least one of an end of the COT (defined in message 305 as a part of the period of time configuration or later in message 309 or 312), an end of a downlink portion of the COT (defined in mes sage 305 as a part of the period of time configuration or later in message 309 or 312), a pre-defined number of slots or symbols and a number of slots or symbols defined in the indication for limiting monitoring (i.e., in message 309) or in the detected PDCCH transmission (i.e., in message 312). In such embodiments, the de termining in block 314 comprises simply selecting said one period of time.

As described in relation to Figure 2B, a flag or an indication bit (a value of which indicates whether or not certain pre-defined period of time is to be used in limiting PDCCH monitoring) may be comprised in the indication for limiting monitoring. Said flag or indication bit may be employed in the determining of the period of time in block 314. In other words, if an indication with an indication bit having a value Ύ is received in block 313, the terminal device may select a pre defined period of time (which may have been configured in elements 304 to 307 or before that). On the other hand, if an indication with an indication bit having a value 'O' is received in block 313, the terminal device may, depending on the em bodiment, continue monitoring of PDCCH transmission without any change (i.e., limiting or suspending of PDCCH monitoring is not triggered) or select a second pre-defined period of time (e.g., configured in elements 304 to 307) for use in lim iting or suspending of PDCCH monitoring.

As described above, the terminal device may, in some embodiments, be configured to employ a plurality of periods of time defined in a plurality of pe riod of time configurations. In such embodiments, the determining in block 314 may comprise selecting a period of time from a plurality of periods of time de fined in said plurality of period of time configurations, for example, based on in formation comprised in the indication for limiting monitoring. The indication for limiting monitoring may explicitly indicate which period of time to use or it may comprise information based on which the period of time may be determined (in block 314).

After the period of time has been determined in block 314, the termi nal device limits or suspends, in block 315, monitoring of PDCCH transmissions associated with CORESETs having an active TCI state other than the first active TCI state for said period of time, similar to as described in relation block 203 of Figure 2. After the period of time has passed, the terminal device continues, in block 316, normal monitoring of PDCCH transmission according to its configura tion (i.e., continues the monitoring started in block 308).

In some embodiments, blocks 312, 313 of Figure 3 maybe omitted. In such embodiments, the receiving of the indication for limiting monitoring may be implicit in the sense that the period of time following the detection (or detection time instance) in block 310 and the corresponding PDCCH monitoring behavior (i.e., blocks 311, 314, 315) at the terminal device may be determined, in response to the detecting in block 310, based on a configuration of the terminal device. Spe cifically, said configuration of the terminal device may be fixed or (pre-) deter mined in the specifications, configured via higher layers (i.e., using a RRC proto col), derived based on contents (or specifically contents other than the indication for limiting monitoring) of unicast or group-common PDCCH transmission re ceived by the terminal device from the access node or determined according any combination of the means listed above.

According to one such (simplistic) embodiment, the terminal device performs the following. First, the terminal device monitors, according to block 308, PDCCH transmissions according to a first set of rules. The first set of rules comprises rules for performing monitoring over at least two beam pair links, each beam pair link corresponding to a CORESET with a different active TCI state. The terminal device detects, according to block 310, a PDCCH transmission (i.e., mes sage 309) from a first beam pair link corresponding to a first CORESET with a first active TCI state, where the detecting indicates (or defines) a start of a COT (i.e., a start of the channel occupancy), according to block 311). Specifically, by receiving the PDCCH transmission corresponding to the first CORESET with the first active TCI state, the terminal device detects that the COT associated with the first CORESET and the first active TCI state has started. Finally, the terminal device limits, according to block 315, in response to the detecting, monitoring of PDCCH transmissions associated with CORESETs having an active TCI state other than the first active TCI state for a period of time.

Figure 4 illustrates an exemplary monitoring operation according to an embodiment. Specifically, the illustrated example corresponds to the case where the terminal device is configured so that the period of time for suspending PDCCH transmissions is defined to expire upon an end of a COT. In the illustrated example, a terminal device detects a start or presence of the COT and receives a Group Common (GC) -PDCCH transmission in a first CORESET 401 with a first ac tive TCI state in the beginning of slot n. Here, the received GC-PDCCH content is assumed to include the following indications:

• a slot where the COT ends (i.e., slot n+2 in this example) and

• an indication for liming monitoring defining that a terminal device shall suspend monitoring in CORESETs with other active TCI state(s) until the end of the COT. After the start of the COT, the terminal device buffers symbols according to the first active TCI state of the first CORESET. The elements 402, 403 correspond, re spectively, to PDSCH and the first CORESET (carrying no DCI).

As the indication for limiting monitoring indicates to suspend active TCI states other than the first active TCI state, the terminal device does not moni tor a second CORESET active with a second active TCI state and its corresponding associated search spaces at slot n+ 1, as is indicated by element 404. Instead, the terminal device waits until the end of the slot n+ 2, i.e., the end of the slot in which the COT ends, and only then detects the second CORESET with the second active TCI state in element 405. The end of the COT may be communicated to the termi nal device after the end of the slot n+2.

It should be noted that the embodiments discussed above are specifi cally targeting the scenario where PDCCH monitoring occasions for two (or more) search spaces associated with CORESETs with different active TCI states overlap, at least partially. If there is no such overlap, the terminal device follows or buffers the active TCI state of the latest CORESET following conventional NR functionali ties.

The blocks, related functions, and information exchanges described above by means of Figures 2A, 2B, 3 and 4 are in no absolute chronological order, and some of them may be performed simultaneously or in an order differing from the given one. In some embodiments, some of the steps may be neglected, for ex ample, if the relevant information is already available (e.g., stored to a memory).

Figure 5 illustrates an apparatus 501 configured to carry out the func tions described above in connection with a terminal device. The apparatus may, for example, correspond to any of the terminal devices 100, 102 of Figure 1. The apparatus may be an electronic device comprising electronic circuitries. The ap paratus may be a separate network entity or a plurality of separate entities. The apparatus may comprise a communication control circuitry 520, such as at least one processor, and at least one memory 530 including a computer program code (software) 531 wherein the at least one memory and the computer program code (software) are configured, with the at least one processor, to cause the apparatus to carry out any one of the embodiments of the terminal device described above.

The memory 530 may comprise a database 532 which may comprise information on, for example, one or more configurations for the monitoring of PDCCH transmissions and/or for the period(s) of time to be used in limiting moni toring. The memory 530 may also comprise other databases which may not be re- lated to the described PDCCH monitoring functionalities configuration functional ities according to embodiments.

Referring to Figure 5, the communication control circuitry 520 may comprise downlink monitoring circuitry 521. The downlink monitoring circuitry 521 maybe configured, for example, to carry out at any of the processes of Fig ures 2A and/or any of the processes performed by the terminal device in Figure 3.

Figure 6 illustrates an apparatus 601 configured to carry out the func tions described above in connection with an access node. The apparatus may, for example, correspond to the access node 104 of Figure 1. The apparatus may spe cifically be a gNB or eNB. The apparatus may be an electronic device comprising electronic circuitries. The apparatus may be a separate network entity or a plural ity of separate entities. The apparatus may comprise a communication control cir cuitry 620 such as at least one processor, and at least one memory 630 including a computer program code (software) 631 wherein the at least one memory and the computer program code (software) are configured, with the at least one pro cessor, to cause the apparatus to carry out any one of the embodiments of the ac cess node described above.

The memory 630 may comprise a database 632 which may comprise, for example, information on one or more configurations for used or to be used by a terminal device for performing (downlink) monitoring and/or one or more con figurations for period(s) of time (i.e., period of time configurations) used or to be used by a terminal device for limiting or suspending (downlink) monitoring, as described in previous embodiments. The memory 630 may also comprise other databases which may not be related to the functionalities of the access node ac cording to any of presented embodiments such as any databases used by relay or donor nodes in conventional operation.

Referring to Figure 6, the communication control circuitry 620 may comprise terminal device configuration circuitry 621 configured to configure ter minal devices to perform downlink monitoring according to any of presented em bodiments. The terminal device configuration circuitry 621 may be configured to carry out at least some of actions relating to Figure 2B and/or to elements blocks 301, 304, 305, 309, 312 of Figure 3.

The apparatuses 501, 601 described in relation to Figures 5 and 6 may further comprise communication interfaces (Tx/Rx) 510, 610 comprising hard ware and/or software for realizing communication connectivity according to one or more communication protocols. The communication interface may provide the apparatus with communication capabilities to communicate in the cellular com munication system and enable communication, for example, with network nodes and terminal devices. Specifically, the communication interfaces 510 of Figure 5 may enable communication with one or more access nodes and the communica tion interfaces 610 of Figure 6 may enable communication with one or more ter minal devices and one or more core network elements. The communication inter face 510, 610 may comprise standard well-known components such as an ampli fier, filter, frequency-converter, (de) modulator, and encoder/decoder circuitries and one or more antennas. The communication interfaces 510, 610 may comprise radio interface components providing the apparatus with radio communication capability in the cell.

The communications interfaces 510 of the apparatus 501 may specifi cally comprise a single antenna panel (i.e., a single, typically flat antenna array) which in turn comprises a plurality of antenna elements. Said single antenna panel (i.e., a single, typically flat antenna array) as well as the apparatus 501 as a whole may be configured to operate using unlicensed spectrum (e.g., using the 60 GHz band and/or the FR1 band).

The memories of the apparatuses described in relation to Figures 5 and 6 may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.

As used in this application, the term "circuitry may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as appli cable):

(i) a combination of analog and/or digital hardware cir- cuit(s) with software/firmware and

(ii) any portions of hardware processor(s) with soft ware (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform vari ous functions) and

(c) hardware circuit(s) and or processor(s), such as a microproces- sor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for oper ation.

This definition of circuitry applies to all uses of this term in this appli cation, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a base band integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

In an embodiment, at least some of the processes described in connec tion with Figures 2A, 2B, 3 and 4 may be carried out by an apparatus comprising corresponding means for carrying out at least some of the described processes. Some example means for carrying out the processes may include at least one of the following: detector, processor (including dual-core and multiple-core proces sors), digital signal processor, controller, receiver, transmitter, encoder, decoder, memory, RAM, ROM, software, firmware, display, user interface, display circuitry, user interface circuitry, user interface software, display software, circuit, antenna, antenna circuitry, and circuitry. In an embodiment, the at least one processor, the memory, and the computer program code form processing means or comprises one or more computer program code portions for carrying out one or more oper ations according to any one of the embodiments of Figures 2A, 2B, 3 and 4 or op erations thereof.

The techniques and methods described herein may be implemented by various means. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or combinations thereof. For a hardware implementation, the appa ratuses) of embodiments may be implemented within one or more application- specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field program mable gate arrays (FPGAs), processors, controllers, micro-controllers, micropro cessors, other electronic units designed to perform the functions described herein, or a combination thereof. For firmware or software, the implementation can be carried out through modules of at least one chipset (procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory unit and executed by processors. The memory unit may be implemented within the processor or externally to the processor. In the latter case, it can be communicatively coupled to the processor via various means, as is known in the art. Additionally, the components of the systems described herein may be rearranged and/or complemented by additional components in order to facilitate the achievements of the various aspects, etc., described with regard thereto, and they are not limited to the precise configurations set forth in the given figures, as will be appreciated by one skilled in the art.

Embodiments as described above may also be carried out in the form of a computer process defined by a computer program or portions thereof. Em bodiments of the methods described in connection with Figures 2A, 2B, 3 and 4 may be carried out by executing at least one portion of a computer program com prising corresponding instructions. The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, which may be any entity or device capable of carrying the program. For example, the computer program may be stored on a computer pro gram distribution medium readable by a computer or a processor. The computer program medium may be, for example but not limited to, a record medium, com puter memory, read-only memory, electrical carrier signal, telecommunications signal, and software distribution package, for example. The computer program medium may be a non-transitory medium. Coding of software for carrying out the embodiments as shown and described is well within the scope of a person of ordi nary skill in the art.

According to an embodiment, there is provided an electromagnetic sig nal using a first CORESET associated with a first active TCI state and carrying computer-readable data comprising an indication indicating whether or not to limit monitoring of PDCCH transmissions associated with CORESETs having an active TCI state other than the first active TCI state for a period of time. Said elec tromagnetic signal may correspond to transmission in block 211 and/or to mes sage 312 of Figure 3. The limiting of the monitoring of PDCCH transmissions and/or the period of time may be defined as described in relation to any of the previous embodiments. Moreover, the indication may be the indication for limit ing monitoring as defined in any of the embodiments described above. The indica tion may be, for example, an indication bit and/or information on a number of slots or symbols defining said period of time.

Even though the invention has been described above with reference to an example according to the accompanying drawings, it is clear that the invention is not restricted thereto but can be modified in several ways within the scope of the appended claims. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the in ventive concept can be implemented in various ways. Further, it is clear to a per son skilled in the art that the described embodiments may, but are not required to, be combined with other embodiments in various ways.