REPORTING CONFIGURATION FOR NON-TERRESTRIAL NETWORK

Cross Reference to Related Application

This application claims priority of PCT Application Serial Number PCT/CN2022/123638 filed on September 30, 2022 with title of "METHODS AND APPARATUS FOR DETERMINING POWER HEADROOM REPORTING CONFIGURATION FOR NON-TERRESTRIAL NETWORK", the entire contents of which are incorporated herein by reference.

Technical Field

The embodiments herein relate generally to the field of communication, and more particularly, the embodiments herein relate to methods and apparatus for determining Power Headroom Reporting (PHR) configuration for a Non-Terrestrial Network (NTN).

Background

In 3GPP, 5G system (5GS) is a new generation’s radio access technology intended to serve use cases such as enhanced mobile broadband (eMBB), ultra-reliable and low latency communication (URLLC), Narrow Band Internet of Things (NB-IoT), and massive Machine Type Communication (mMTC). 5G includes the New Radio (NR) access stratum interface and the 5G Core Network (5GC). The New Radio (NR) physical and higher layers are reusing parts of the Long Term Evolution (LTE) specification, and add needed components to the LTE specification when motivated by new use cases. To benefit from the strong mobile ecosystem and economy of scale, the satellite network based on the terrestrial wireless access technologies including LTE and NR for satellite networks, is being specified in the 3GPP standard.

The low complexity and low cost UEs (e.g. NB-IoT NTN UEs) have different characteristics compared to legacy UEs. These characteristics result in some limitations. One such limitation is that these UEs have limited reporting capabilities compared to legacy UEs, and thus less accurate or less reliable power headroom reporting may result from these UEs.

Summary

It is therefore an object of the present disclosure to propose methods, UE, computer readable medium and computer program product for determining or selecting a PHR configuration for a NTN.

According to a first aspect, a method, performed by a UE, is provided. In the method, the UE selects, out of at least two PHR mapping tables, a PHR mapping table for use by the UE for reporting a Power Headroom (PH) value for a cell. The cell is managed by an NTN node. The PHR mapping table for the reporting is selected based on a type of the NTN node. The UE then transmits a reported PH value, selected from the selected PHR mapping table, to a network node serving the UE.

In an embodiment, the step selecting a PHR mapping table for reporting the PH value based on the type of the NTN node may further comprise selecting a first PHR mapping table among at least two PHR mapping tables when the type of the NTN node is a first type.

In an embodiment, the step of selecting a PHR mapping table for reporting the PH value based on the type of the NTN node may further comprise selecting a second PHR mapping table among the at least two PHR mapping tables when the type of the NTN node is a second type.

In an embodiment, the first and second PHR mapping tables may differ in terms of at least one of: a reporting resolution, a reporting range, a maximum reportable value, a minimum reportable value.

In an embodiment, the maximum reportable value of the second PHR mapping table may be higher than the maximum reportable value of the first PHR mapping table.

In an embodiment, the minimum reportable value of the first PHR mapping table may be lower than the minimum reportable value of the second PHR mapping table.

In an embodiment, the reporting resolution for negative reportable values of the first PHR mapping table may be higher than the reporting resolution for negative reportable values of the second PHR mapping table. In this embodiment, the reporting resolution for positive reportable values of the first PHR mapping table may be lower than the reporting resolution for positive reportable values of the second PHR mapping table.

In an embodiment, the reporting resolution for negative reportable values of the first PHR mapping table may be higher than the reporting resolution for negative reportable values of the second PHR mapping table. In this embodiment, the reporting range for positive reportable values of the first PHR mapping table may be lower than the reporting range for positive reportable values of the second PHR mapping table.

In an embodiment, the method may further comprise the step of estimating a PH value as a measured quantity value for the cell. The method may further comprise the step of selecting the reported PH value from the selected PHR mapping table based on the measured quantity value for the cell.

In an embodiment, the network node serving the UE is the NTN node serving the UE in the cell, a base station (BS) serving the UE in the cell and being connected to the NTN node via a gateway, or a second network node serving the UE in a second cell that is different from the cell.

In an embodiment, the cell is a Primary Cell (P-Cell) for the UE and the second cell is a Secondary Cell (S-Cell) for the UE.

In an embodiment, the cell is a S-Cell for the UE and the second cell is a P-Cell for the UE.

In an embodiment, the UE may be a NB-IoT device.

In an embodiment, the UE may transmit the reported PH value by using 2 bits within message 3 (Msg3) in a random access procedure.

In an embodiment, the UE may further indicate an index of the determined PHR mapping table by using an additional 1 -bit indicator.

In an embodiment, the UE may further indicate a PHR table indicator to indicate the PHR mapping table used by the UE.

In an embodiment, the UE may be operated in a normal coverage mode or an enhanced coverage mode.

In an embodiment, at least one of the NTN node and the network node serving the UE may be one of: a satellite node or a satellite access node (SAN), a high altitude platform BS (HAPS), a drone base station.

In an embodiment, the type of the NTN node may include a Non-Geostationary Earth Orbit Satellite (NGSO) type and a Geostationary Earth Orbit Satellite (GSO) type.

In an embodiment, the NGSO type may include a Low Earth Orbit (LEO) satellite type and a Medium Earth Orbit (MEO) satellite type, and the GSO type may include a Geostationary Earth Orbit (GEO) satellite type.

In an embodiment, the selected PHR mapping table may include 4 selectable reported values, in which: a reported value POWER HEADROOM O may be used for reporting a measured quantity value greater than or equal to -54 dB and less than 5 dB, a reported value P0WER HEADR00M 1 may be used for reporting a measured quantity value greater than or equal to 5 dB and less than 8 dB, a reported value P0WER HEADR00M 2 may be used for reporting a measured quantity value greater than or equal to 8 dB and less than 11 dB, and a reported value P0WER HEADR00M 3 may be used for reporting a measured quantity value greater than or equal to 1 IdB.

In an embodiment, the selected PHR mapping table may include 4 selectable reported values, in which: a reported value POWER HEADROOM O may be used for reporting a measured quantity value greater than or equal to -54 dB and less than -10 dB, a reported value POWER HEADROOM 1 may be used for reporting a measured quantity value greater than or equal to -10 dB and less than -2 dB, a reported value P0WER HEADR00M 2 may be used for reporting a measured quantity value greater than or equal to -2 dB and less than 6 dB, and a reported value P0WER HEADR00M 3 may be used for reporting a measured quantity value greater than or equal to 6 dB.

According to a second aspect, a UE, configured to perform the method of the first aspect, is provided. The UE comprises: at least one processor; and a non-transitory computer readable medium coupled to the at least one processor. In an embodiment, the non-transitory computer readable medium may store instructions executable by the at least one processor, whereby the at least one processor may be configured to perform the above methods related to the above UE.

According to a third aspect, a computer readable medium is provided. The computer readable medium stores computer readable code, which when run on an apparatus, causes the apparatus to perform any of the above methods.

According to a third aspect, a computer program product is provided. The computer program product stores computer readable code, which when run on an apparatus, causes the apparatus to perform any of the above methods.

With the embodiments herein, the PHR configuration may be adapted to the operating scenario, and thus the embodiments may allow the UE (for example the low complexity and low cost UE) to report more accurate information about the actual power usage in the UE. As a result, the network side may adapt the uplink transmission parameters for the UE based on the actual reported PHR information.

Brief Description of the Drawings

The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments of the present disclosure and, together with the description, further serve to explain the principles of the disclosure and to enable a person skilled in the pertinent art to make and use the embodiments disclosed herein. In the drawings, like reference numbers indicate identical or functionally similar elements, and in which:

Figure 1 shows an example architecture of a satellite network;

Figure 2 shows the orbital elements for a satellite;

Figure 3A is a schematic flow chart showing an example method in the UE, according to the embodiments herein;

Figure 3B is a schematic flow chart showing an example method in the UE, according to the embodiments herein;

Figure 4 is a schematic block diagram showing an example UE, according to the embodiments herein; and

Figure 5 is a schematic block diagram showing an example computer-implemented apparatus, according to the embodiments herein.

Detailed Description of Embodiments

Embodiments herein will be described in detail hereinafter with reference to the accompanying drawings, in which embodiments are shown. These embodiments herein may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. The elements of the drawings are not necessarily to scale relative to each other.

Reference to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrase "in an embodiment" appearing in various places throughout the specification are not necessarily all referring to the same embodiment.

In this disclosure, the term "satellite" is often used even when a more appropriate term would be "base station (BS) or radio network node (RNN) associated with the satellite". The term "satellite" may also be called as a satellite node, satellite access node (SAN), a NTN node, node in the space etc. Here, BS or RNN associated with a satellite might include both a regenerative satellite, where the BS or RNN is the satellite payload, i.e. the BS or RNN is integrated with the satellite, or a transparent satellite, where the satellite payload is a relay and BS or RNN is on the ground (i.e. the satellite relays the communication between the BS or RNN on the ground and the UE).

Time period or duration over which a UE can maintain connection, or can camp on, or can maintain communication, and so on to a satellite or base station, e.g. a gNB, is referred to as term "coverage time" or "serving time" or "network availability" or "sojourn time" or "dwell time" etc. The term "Non-coverage time", also known as "non-serving time" or "network unavailability", or "non-sojoum time" or "non-dwell time" refers to a period of time during which a satellite or gNB cannot serve or communicate or provide coverage to a UE. Another way to interpret the availability is that it is not about a satellite/network strictly not being able to serve the UE due to lack of coverage but that the UE does not need to measure certain "not likely to be serving cell (satellite via which serving cell is broadcasted)". In this case, the terminology may still be as in no coverage case or it may be different, e.g. "no need to measure".

The term "node" is used which can be a network node or a user equipment (UE). Examples of network nodes are NodeB, base station (BS), multi-standard radio (MSR) radio node such as MSR BS, eNodeB, gNodeB, MeNB, SeNB, satellite access node (SAN), location measurement unit (LMU), integrated access backhaul (IAB) node, network controller, radio network controller (RNC), base station controller (BSC), relay, donor node controlling relay, base transceiver station (BTS), Central Unit (e.g. in a gNB), Distributed Unit (e.g. in a gNB), Baseband Unit, Centralized Baseband, C-RAN, access point (AP), transmission points, transmission nodes, transmission reception point (TRP), RRU, RRH, nodes in distributed antenna system (DAS), core network node (e.g. MSC, MME etc), O&M, OSS, SON, positioning node (e.g. E-SMLC), etc.

The non-limiting term "UE" refers to any type of wireless device communicating with a network node and/or with another UE in a cellular or mobile communication system. Examples of UE are target device, device to device (D2D) UE, vehicular to vehicular (V2V), machine type UE, MTC UE or UE capable of machine to machine (M2M) communication, PDA, tablet, mobile terminals, smart phone, laptop embedded equipment (LEE), laptop mounted equipment (LME), USB dongles etc.

The term "radio access technology", or "RAT", may refer to any RAT, e.g. UTRA, E-UTRA, narrow band internet of things (NB-IoT), Wi-Fi, Bluetooth, next generation RAT, New Radio (NR), 4G, 5G, NR NTN, loT NTN, LTE NTN, etc. Any of the equipment denoted by the terms "node", "network node" or "radio network node" may be capable of supporting a single or multiple RATs.

The term "signal" or "radio signal" used herein can be any physical signal or physical channel. Examples of downlink (DL) physical signals are reference signal (RS) such as PSS, SSS, CSI-RS, DMRS signals in SS/PBCH block (SSB), discovery reference signal (DRS), CRS, PRS, NPSS, NSSS, NRS, etc. RS may be periodic e.g. RS occasion carrying one or more RSs may occur with certain periodicity e.g. 20 ms, 40 ms etc. The RS may also be aperiodic. Each SSB carries NR-PSS, NR-SSS and NR-PBCH in 4 successive symbols. One or multiple SSBs are transmit in one SSB burst which is repeated with certain periodicity e.g. 5 ms, 10 ms, 20 ms, 40 ms, 80 ms and 160 ms. The UE is configured with information about SSB on cells of certain carrier frequency by one or more SS/PBCH block measurement timing configuration (SMTC) configurations. The SMTC configuration comprising parameters such as SMTC periodicity, SMTC occasion length in time or duration, SMTC time offset with regard to reference time (e.g. serving cell’s SFN) etc. Therefore, SMTC occasion may also occur with certain periodicity e.g. 5 ms, 10 ms, 20 ms, 40 ms, 80 ms and 160 ms. Examples of uplink (UL) physical signals are reference signal such as SRS, DMRS etc. The term physical channel refers to any channel carrying higher layer information e.g. data, control etc. Examples of physical channels are PBCH, NPBCH, PDCCH, PDSCH, sPUCCH, sPDSCH, sPUCCH, sPUSCH, MPDCCH, NPDCCH, NPDSCH, E-PDCCH, PUSCH, PUCCH, NPUSCH etc.

The term "time resource" used herein may correspond to any type of physical resource or radio resource expressed in terms of length of time. Examples of time resources are: symbol, time slot, subframe, radio frame, TTI, interleaving time, slot, sub-slot, mini-slot, system frame number (SFN) cycle, hyper-SFN (H-SFN) cycle, DRX cycle, extended DRX cycle (eDRX) etc.

The term "power headroom report configuration", or "power headroom reporting (PHR) configuration" comprises at least one of a PHR resolution and PHR ranges (the maximum and minimum reportable PHR values). The terms "PHR configuration", "PHR reporting configuration" and "reporting configuration" are interchangeably used but have the same meaning.

It should also be understood that, a network node or a network function can be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., on a cloud infrastructure. loT NTN and NTN Characteristics

Figure 1 shows an example architecture of a satellite network 100. As shown in Figure 1, a satellite radio access network 100 may include the following components:

• A satellite 102 that refers to a space-home platform.

• An earth-based gateway 103 that connects the satellite to a base station (BS) 104 or a core network, depending on the choice of architecture.

• Feeder link that refers to the link between a gateway 103 and a satellite 102.

• Access link, or service link, that refers to the link between a satellite 102 and a UE 101.

Depending on the orbit altitude, a satellite 102 may be categorized as low earth orbit (LEO), medium earth orbit (MEO), or geostationary earth orbit (GEO) satellite.

• LEO: typical heights ranging from 250 - 1,500 km, with orbital periods ranging from 90 - 120 minutes.

• MEO: typical heights ranging from 5,000 - 25,000 km, with orbital periods ranging from 3 - 15 hours.

• GEO: height at about 35,786 km, with an orbital period of 24 hours.

Two basic architectures can be distinguished for satellite communication networks, depending on the functionality of the satellites in the system:

Transparent payload (also referred to as bent pipe architecture). The satellite forwards the received signal between the terminal and the network equipment on the ground with only amplification and a shift from uplink frequency to downlink frequency. When applied to general 3GPP architecture and terminology, the transparent payload architecture means that the gNB is located on the ground and the satellite forwards signals/data between the gNB and the UE.

Regenerative payload. The satellite includes on-board processing to demodulate and decode the received signal and regenerate the signal before sending it back to the earth. When applied to general 3GPP architecture and terminology, the regenerative payload architecture means that the gNB is located in the satellite.

In the work item for NR NTN in 3GPP release 17, only the transparent payload architecture is considered.

A satellite network or satellite based mobile network may also be called as NTN. On the other hand, mobile network with base stations on the ground may also be called as terrestrial network (TN) or non-NTN network. A satellite within NTN may be called as NTN node, NTN satellite or simply a satellite.

In the example in Figure 1, an example architecture of a satellite network with bent pipe transponders (i.e. the transparent payload architecture) is shown. The gNB (shown as BS 104) may be integrated in the gateway 103 or connected to the gateway 103 via a terrestrial connection (wire, optic fiber, wireless link).

A communication satellite typically generates several beams over a given area. The footprint of a beam is usually in an elliptic shape, which has traditionally been considered as a cell (such as the cell 110 in Figure 1), but cells consisting of the coverage footprint of multiple beams are not excluded in the 3GPP work. The footprint of a beam is also often referred to as a "spotbeam" (as shown in Figure 1). The footprint of a beam may move over the earth’s surface with the satellite movement or may be earth fixed with a beam pointing mechanism used by the satellite to compensate for the satellite’s motion. The size of a spotbeam depends on the system design, which may range from tens of kilometers to a few thousands of kilometers.

In a LEO or MEO communication system, a large number of satellites deployed over a range of orbits are required to provide continuous coverage across the full globe. Launching a mega satellite constellation is both an expensive and time-consuming procedure. It is therefore expected that all LEO and MEO satellite constellations for some time will only provide partial earth-coverage. In case of some constellations dedicated to massive loT services with relaxed latency requirements, it may not even be necessary to support full earth-coverage. It may be sufficient to provide occasional or periodic coverage according to the orbital period of the constellation.

A 3GPP device in RRC IDLE or RRC INACTIVE state is required to perform a number of procedures including measurements for mobility purposes, paging monitoring, logging measurement results, tracking area update, and searching for a new Public Land Mobile Network (PLMN), to mention a few. These procedures will consume power in devices, and a general trend in 3GPP has been to allow for relaxation of these procedures to prolong device battery life. This trend has been especially pronounced for loT devices supported by reduced capability (redcap), NB loT and LTE-Machine Type Communication (LTE M).

Propagation delay is an important aspect of satellite communications that is different from the delay expected in a terrestrial mobile system. For a bent pipe satellite network, the round-trip delay may, depending on the orbit height, range from tens of ms in the case of LEO satellites to several hundreds of ms for GEO satellites. As a comparison, the round-trip delays in terrestrial cellular networks are typically below 1 ms.

The distance between the UE 101 and a satellite 102 can vary significantly, depending on the position of the satellite 102, and thus the elevation angle s seen by the UE 101. Assuming circular orbits, the minimum distance is realized when the satellite 102 is directly above the UE 101 (;: = 90°), and the maximum distance when the satellite 102 is at the smallest possible elevation angle. Table 1 shows the distances between satellite 102 and UE 101 for different orbital heights and elevation angles together with the one-way propagation delay and the maximum propagation delay difference (the difference from the propagation delay at s = 90°). Note that this table assumes regenerative payload architecture. For the transparent payload case, the propagation delay between gateway and satellite needs to be considered as well, unless the base station corrects for that.

Table 1: Propagation delay for different orbital heights and elevation angles.

The propagation delay may also be highly variable due to the high velocity of the LEO and MEO satellites and change in the order of 10 - 100 ps every second, depending on the orbit altitude and satellite velocity.

Ephemeris data

In 3GPP TR 38.821, it has been captured that ephemeris data should be provided to the UE 101, for example to assist with pointing a directional antenna (or an antenna beam) towards the satellite 102. A UE 101 knowing its own position, e.g. thanks to Global Navigation Satellite System (GNSS) support, may also use the ephemeris data to calculate correct timing related and/or frequency drifts e.g. Timing Advance (TA) and Doppler shift. The contents of the ephemeris data and the procedures on how to provide and update such data have not yet been studied in detail.

A satellite orbit can be fully described using 6 parameters. Exactly which set of parameters is used can be decided by the user; many different representations are possible. For example, a choice of parameters used often in astronomy is the set (a, e, i, . co, t). Here, the semi -major axis a and the eccentricity s describe the shape and size of the orbit ellipse; the inclination i, the right ascension of the ascending node , and the argument of periapsis co determine its position in space, and the epoch t determines a reference time (e.g. the time when the satellites moves through periapsis). Figure 2 shows the orbital elements for a satellite 102, which illustrates this set of parameters.

A two-line element set (TLE) is a data format encoding a list of orbital elements of an Earth-orbiting object for a given point in time, the epoch. As an example of a different parametrization, TLEs use mean motion n and mean anomaly AL instead of a and t. A completely different set of parameters is the position and velocity vector (x, y, z, vx, vy, vz) of a satellite 102. These are sometimes called orbital state vectors. They can be derived from the orbital elements and vice versa since the information they contain is equivalent. All these formulations (and many others) are possible choices for the format of ephemeris data to be used in NTN.

Additionally, the ephemeris data may be accompanied with information on possible coverage area, or timing information when the satellite is going to serve a certain geographical area on Earth.

NB-IoT

The objective of Narrow Band Internet of Things (NB-IoT) is to specify a radio access for cellular internet of things (loT), based to a great extent on a non-backward-compatible variant of E-UTRA, that addresses improved indoor coverage, support for massive number of low throughput devices, low delay sensitivity, ultra-low device cost, low device power consumption and (optimized) network architecture.

The NB-IoT carrier BW (Bw2) is 200 KHz. Examples of operating bandwidth (Bwl) of LTE are 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, 20 MHz etc.

NB-IoT supports 3 different modes of operation:

1). ‘Stand-alone operation’ utilizing for example the spectrum currently being used by GERAN systems as a replacement of one or more GSM carriers. In principle it operates on any carrier frequency which is neither within the carrier of another system nor within the guard band of another system’s operating carrier. The other system can be another NB-IoT operation or any other RAT e.g. LTE, NR.

2). ‘Guard band operation’ utilizing the unused resource blocks within a LTE carrier’s guard-band or NR carrier’s guard-band. The term guard band may also interchangeably called guard bandwidth. As an example in case of LTE BW of 20 MHz (i.e. Bwl= 20 MHz or 100 RBs), the guard band operation of NB-IoT can be placed anywhere outside the central 18 MHz but within 20 MHz LTE BW.

3). ‘In-band operation’ utilizing resource blocks (RBs) within a normal LTE carrier or NR carrier. The in-band operation may interchangeably be called in-bandwidth operation. More generally the operation of one RAT within the BW of another RAT may also be called in-band operation. As an example in a LTE BW of 50 RBs (i.e. Bwl of 0 MHz or 50 RBs), NB-IoT operation over one resource block (RB) within the 50 RBs may be called in-band operation.

In NB-IoT, the downlink transmission is based on Orthogonal Frequenc -Division Multiplexing (OFDM) with 15 kHz subcarrier spacing for all the scenarios: standalone, guard-band, and in-band.

• For UL transmission, both multi-tone transmissions based on Single Carrier Frequency Division Multiple Access (SC-FDMA), and single tone transmission is supported

This means that the physical waveforms for NB-IoT in downlink and also partly in uplink is similar to legacy LTE.

In the downlink design, NB-IoT supports both master information broadcast and system information broadcast which are carried by different physical channels. For in-band operation, it is possible for NB-IoT UE to decode NB-PBCH without knowing the legacy PRB index. NB-IoT supports both downlink physical control channel (NB-PDCCH, or NB-M-PDCCH) and downlink physical shared channel (PDSCH). The operational mode (e.g. standalone, guard band, in-band) of NB-IoT is indicated to the UE e.g. in system information such as in NB-MIB. The downlink synchronization signals consist of NB-IoT primary synchronization signal (NPSS) and NB-IoT secondary synchronization signal (NSSS). The downlink reference signal is NB-IoT reference signal (NRS).

Furthermore, in NB-IoT anchor and non-anchor carriers are defined. In anchor carrier the UE assumes that NPSS/NSSS/NPBCH/SIB-NB are transmitted by a base station in the downlink. In non-anchor carrier the UE assumes that NPSS/NSSS/NPBCH/SIB-NB are NOT transmitted by the base station in the downlink. The anchor carrier is transmitted on subframes #0, #4, #5 in every frame and subframe #9 in every other frame. The anchor carriers transmitting NPBCH/SIB-NB contain also NRS. The non-anchor carrier contains NRS during certain occasions and UE specific signals such as NPDCCH and NPDSCH. The non-anchor carrier can be transmitted in any subframe other than those containing the anchor carrier. The resources for non-anchor carrier are configured by the network node. For example, the BS (e.g. eNB) transmits a bit map of DL subframes using IE (DL-Bitmap-NB) which are configured as non-anchor carrier. The anchor carrier and/or non-anchor carrier may typically be operated by the same network node e.g. by the serving cell. But the anchor carrier and/or non-anchor carrier may also be operated by different network nodes. The configuration of the non-anchor carriers is signaled to the UE via RRC message.

PH estimation and reporting procedures

The power headroom reporting (PHR) procedure is used by a UE to report its available transmit power to a network node e.g. to a serving cell. In general, PHR or simply power headroom (PH) is a relation between at least the UE’s available transmit power and a reference transmit power. Examples of available transmit power are total available power for transmitting one or more uplink signals. Examples of UL signals are UL reference signal (e.g. SRS), UL channel (e g. UL shared channel (UL-SCH), PUCCH, PUSCH, PRACH etc). Examples of the reference transmit power are UE maximum output power, UE configured maximum power (Pcmax) etc. The reference power used in PH estimation may also include maximum power reduction (MRP) and/or additional MPR (A-MPR). The UE maximum output power may also be called as UE nominal power. The UE nominal or maximum power defines the maximum output power of the UE and may be defined in terms of a power class e.g. power class 1 (e.g. 31 dBm), power class 2 (e.g. 26 dBm), power class 3 (e.g. 23 dBm) etc. The UE determines the available transmit power based on estimation, calculation or measurement of its transmission power over a reference period. The reference period, which may also be called as estimation, measurement or calculation period, may comprise of one or more time resources (e.g. symbol, slot, subframe etc). For example, the UE may estimate its transmission power based on measured transmit power in one or more previous time resources (e.g. symbol, slot, subframe etc) and/or it may be calculated based one or more operational parameters such as transport format, modulation order of signal, target signal quality etc.

In one example, PH is the difference between the reference transmit power and the estimated or calculated transmit power in log scale. In one example, PH is the difference between the UE configured maximum power and the estimated UE transmission power in log scale. The PHR is valuable for the base station (e.g. gNB) to enable efficient power control and link adaptation procedures, ensuring that the UE can reach as high bitrate as possible.

The PH can be estimated and transmitted for each serving cell e.g. PH for sPCell, PH for activated SCell etc. Examples of sPCell are PCell, PSCell etc. The UE may transmit the PH to a network node using MAC or other signaling mechanism e.g. RRC. The UE may transmit the PH periodically, aperiodically or when one or more reporting conditions or criteria are met. The power headroom reporting range can vary be from -Xn dB to Xm dB with a resolution of Xr dB. Examples of Xn, Xm and Xr are -23, 40 and 1 respectively.

An example of the limited reporting capabilities of the low complexity and low cost UEs (e.g. NB-IoT NTN UEs) may be the bits used for reporting the power headroom. For example, the NB-IoT UE has only 2 bits that can be used for reporting the power headroom, and this is much less compared to 6 bits used for PH reporting by legacy LTE UEs. This means that the NB-IoT UE can only report 4 different values while the latter can report up to 64 values of power headroom. The NTN network is operated by different types of satellites which have different characteristics in terms altitudes, speed, orbit etc. One of the commonly used satellites in NTN network is Low Earth Orbit (LEO) and operates at altitudes between 500 km - 1200 km. Another commonly used satellite is Geostationary Orbit (GEO) which operates at altitudes of 35786 km and assumed to be stationary above the equator. Medium Earth Orbit (MEO) satellites, on the other hand, operates at altitudes between LEO and GEO. The pathloss (PL) depends on the type of satellite serving the cell and leads to different power usage for the UL transmissions. For example, the UE served by LEO or MEO is subject to higher pathloss variation compared to those served by GEO satellites.

Since NB-IoT UE can only report fewer values compared to legacy LTE UEs, the reported value may not correctly or reliably reflect the actual power usage in the UE. The reported measurements are used by the network node for operational tasks e.g. scheduling, mobility, positioning etc. Hence, less accurate or less optimal scheduling decisions may be taken by the network node.

In view of the above, the embodiments propose a solution to determine PHR configuration for a NTN based on the type of the serving network node (such as satellite).

The embodiments described herein may be implemented in the wireless communication system 100 as shown in Figure 1. As shown, the wireless communication system 100 may comprise of a UE 101 operating in a cell 110 (also may be referred as celll) served by a network node such as satellite 102 (e.g. SAN1), obtaining information about the type of satellite 102 serving the cell 110 on which one or more signals are operated by the UE 101 from the network node such as satellite 102, e.g. from SAN1. Operation of signals comprises reception and/or transmission of signals between the UE 101 and the cell 110 (e.g. celll). Examples of reception of signals comprise at least receiving of reference signals for measurements, receiving of downlink channels. Examples of transmission of signals comprises at least transmission of uplink reference signals, channels etc.

In an embodiment, a UE 101 may estimate or measure or calculate a power headroom (PH) for the cell 110 (e.g. celll), and further obtain information about the type of satellite 102 serving or operating the cell 110 (e.g. celll) and determine or select one power headroom reporting (PHR) configuration out of at least two possible configurations for reporting or transmitting the PH measurement results to the network node such as satellite 102 or another network node (such as the BS 104). The UE 101 further transmits the estimated PH results according to or based on or using the determined PHR to the network node, e.g. satellite 102 and/or BS 104.

If the serving satellite 102 serving or managing the cell 110 (e.g. celll) belongs to type A (NGSO satellite e.g. LEO satellite), then the UE 101 may determine a first PHR configuration. Otherwise, if the serving satellite 102 belongs to type B (GSO satellite e.g. GEO satellite), then UE 101 may determine a second PHR configuration. The first and second PHR configurations may differ in terms of at least one of:

- The resolution of the reportable values within the reporting range.

- The ranges of the reportable values within the reporting range.

- The maximum reportable value within the reporting range.

- The minimum reportable value within the reporting range.

In one example, if the cell 110 (e.g. cell 1 ) is served by a LEO satellite, then UE 101 may determine or select a first PHR reporting configuration for celll. Otherwise, if the celll is served by a GEO satellite then the UE 101 may determine or select a second PHR reporting configuration for celll, where the reporting range is larger or/and resolution is more granular in the negative range/values in the first configuration compared to the second configuration to account for the more pathloss variation.

The embodiments described are applicable to UE capable of or supporting any one or more Power Classes (PCs), including for example PCI (31 dBm), PC2 (26 dBm), PCI.5 (29 dBm), PC3 (23 dBm), PC5 (20 dBm) etc.

Scenario description

The scenario may comprise a UE (UE1) 101 served by a first serving cell (celll) 110 operating on a first carrier frequency (Fl). Celll may be managed or operated by a first network node (NW1) 102. NW1 may be an example of an NTN node. Examples of the NTN node may be satellite node, high altitude platform BS (HAPS), drone base station, etc. Satellite node may also be called herein as satellite access node (SAN). An example of NW1 may be a first SAN (SAN1), which manages or serves or operates or controls celll.

The UE 101 may further be served by a second serving cell (cell2) (not shown) operating on a second carrier frequency (F2). Cell2 may be served or managed by NW1 or by a second network node (NW2). NW2 may also be example of an NTN node.

Examples of serving cells may be sPCell, SCell, anchor carrier, non-anchor carrier etc. Examples of sPCell may be PCell, PSCell etc. Fl, may be an anchor carrier or may be a non-anchor carrier. In another example, Fl, may be an anchor carrier and F2 may be non-anchor carrier.

In one example, the UE 101 may be configured to estimate the PH for celll and transmit the estimated PH for celll to celll. In another example, the UE 101 may be configured to estimate the PH for cell2 and transmit the estimated PH for cell2 to celll. In another example, the UE 101 may be configured to estimate the PH for cell2 and celll and transmit the estimated PH for cell2 and celll to either celll or on cell2.

The UE 101 may further operate or be configured in a certain coverage enhancement (CE) mode with regard to a certain cell e.g. with regard to celll. Examples of CE levels may be normal CE level, enhanced CE level (or may be called as extended CE level) etc. Normal CE level may also be called as baseline or reference CE level. The CE level may also be called as extended CE level or advanced CE level. In another example CE levels may be enumerated such as CE level # 0 (CEO), CE level # 1 (CE1), CE level # 2 (CE2), CE level # 3 (CE3) and so on.

The coverage level of the UE 101 may be expressed in terms of: received signal quality and/or received signal strength at the UE 101 with regard to a certain cell (e.g. celll, cell2 etc.) and/or received signal quality and/or received signal strength at a certain cell (e.g. celll, cell2 etc) with regard to the UE 101.

Examples of signal quality may be SNR, SINR, CQI, RSRQ, CRS Es/Iot, SCH Es/Iot, NRS Es/Iot, NSCH Es/Iot etc. Examples of signal strength may be path loss, RSRP, SCH RP etc. The notation Es/Iot may be defined as ratio of:

• Es, which is the received energy per RE (power normalized to the subcarrier spacing) during the useful part of the symbol, i.e. excluding the cyclic prefix, at the UE antenna connector, to

• lot which is the received power spectral density of the total noise and interference for a certain RE (power integrated over the RE and normalized to the subcarrier spacing) as measured at the UE antenna connector

Examples of normal and enhanced CE levels in terms of NSCH Es/Iot at the UE with regard to a cell (e.g. celll, cell2) may be:

• normal coverage, when: NSCH Es/Iot > -6 dB and NRS Es/Iot > -6 dB.

• enhanced coverage, when: (-15 dB > NSCH Es/Iot < -6 dB) and (-15 dB > NRS Es/Iot < -6 dB).

Consider another example of 4 coverage levels comprising based on SNR at the UE with regard to a cell (e.g. celll, cell2 etc):

Coverage enhancement level 0 (CEO) comprising SNR -6 dB at UE with regard to a cell;

Coverage enhancement level 1 (CE1) comprising -12 dB < SNR < -6 dB at UE with regard to a cell;

Coverage enhancement level 2 (CE2) comprising -15 dB < SNR < -12 dB at UE with regard to a cell; and

Coverage enhancement level 3 (CE3) comprising -18 dB < SNR < -15 dB at UE with regard to a cell. Figures 3A and 3B are schematic flow charts showing example methods 300 and 320, respectively, in the UE 101, according to the embodiments herein. Figure 3A shows methods in the UE 101 for determining PHR reporting configuration based on satellite type of an NTN cell. The embodiments described herein may also be implemented in any combination and in any order. The UE embodiment comprises at least the following steps performed by the UE 101 :

• Step S301 : Estimating a power headroom (PH) for a cell 110.

• Step S302: Obtaining information about a type of satellite 102 serving a cell 110 (e.g. cell 1) for which the PH is estimated by the UE 101.

• Step S303: Determining a PHR configuration for transmitting a measurement result of the estimated PH based on a type of satellite 102 serving or managing the cell 110.

• Step S304: Transmitting the PH measurement result (i.e. , the reported value) to a network node, e.g. satellite 102 and/or BS 104 using or based on the determined PHR configuration.

Figure 3B shows methods in the UE 101 for reporting a PH value for a cell 110 managed by an NTN node 102. The UE embodiment comprises at least the following steps performed by the UE 101:

• Step S321: Estimating a power headroom (PH) value as a measured quantity value for a cell 110.

• Step S325: Selecting, out of at least two PHR mapping tables, a PHR mapping table for the reporting based on a type of the NTN node 102.

• Step S326: Selecting the reported PH value from the selected PHR mapping table based on the measured quantity value for the cell 110.

• Step S330: Transmitting a reported PH value, selected from the selected PHR mapping table, to a network node serving the UE 101.

Note that, the above steps may be performed in any manner, for example, performed in any sequence, performed at the same time, or performed separately. For example, the UE 101 may firstly perform the step S302 and S303 for determining a PHR configuration, and then perform the step S301 and S304 for reporting the PH based on the determined PHR configuration. Likewise, the UE 101 may in the method 320 perform step S325 before performing step S321, for example. While the description in the below provides detailed information referring to the steps of method 300, the information provided is equally applicable to the method 320 though not organized to strictly follow the steps of this method. Step S301: Estimating a power headroom

In this step, the UE 101 may estimate a power headroom for at least one cell 110 (e.g. celll).

The power headroom may be estimated according to one or more procedures as described in the above "PH estimation and reporting procedures" section. For example, the PH may be defined as the difference between the UE maximum output power and the estimated output power. It is typically expressed in log scale. It is also measured and reported per component carrier (e.g. per serving cell etc.) in case the UE is configured with multicarrier operation e.g. CA, DC, both anchor and non-anchor carriers etc.

In an example, the power headroom may be defined as follows:

PH(i) = PcMAX,c(i)-{Po_PUSCH,c(l)+Ctc(l)’PL _c } (1)

In an example, for a NB-IoT UE, which has a dedicated uplink channel, the power headroom may be defined in a similar way as follows:

PH(i) = PcMAX,c(i)-{Po_NPUSCH,c(l)+Ctc(l)’PL _c } (2)

Where,

• Pcmax.c is the configured UE transmit power of the UE 101 for the serving cell 110, c (e.g. celll).

• PL _C is the path loss between the UE 101 and serving cell 110, c. It is calculated by the UE 101.

• PO_PUSCH,C or PQ_NPUSCH,C is a parameter configured by a network node 102 for the serving cell 110, c.

• a _c is a parameter provided by the higher layer for the serving cell, c

Step S302: UE obtaining information about satellite type

In this step, the UE 101 may obtain information about the type of satellite 102 serving, managing or operating the UE 101 in the cell 110 (e.g. celll) for which the PH is estimated by the UE 101. The obtained information may comprise:

Type of satellites, e.g. NGSO, GSO. Specific examples of satellites may be LEO, MEO, GEO etc. For example, the NGSO satellite may be LEO or MEO, while the GSO satellite may be GEO.

The UE 101 may obtain the information about the type of satellite 102 serving or managing the cell 110 (e.g. celll) for which the PH is estimated by the UE 101 based on one or more of the following mechanisms:

• By receiving information (e.g. Radio Resource Control (RRC) message), which identifies the type of the satellite 102, from a network node such as satellite 102 or BS 104, e.g. from the serving cell 110 of the UE.

• By acquiring the system information (e.g. master information block (MIB), one or more System Information Blocks (SIBs)) of the cell 110 (e.g. celll) for which the PH is estimated by the UE 101.

• Based on historical data or statistics. For example, if a certain cell (based on e.g. cell ID, global cell ID, carrier frequency of the cell etc) has been consistently served by GSO satellite in the past then the UE 101 may assume that the cell is served by GSO satellite (e.g. GEO satellite). In another example, if a certain cell has been consistently served by NGSO satellite in the past in certain location or geographical area then the UE may assume that the cell is served by NGSO satellite (e.g. LEO satellite).

Step S303: determining a PHR configuration based on the satellite type

In this step, the UE 101 may determine one PHR configuration out of at least two possible configurations for reporting PH for the cell (e.g. celll, cell2 etc.) to a network node such as satellite 102 or BS 104 based on at least a type of the satellite 102 serving or managing or controlling the cell 110 for which the PH is estimated by the UE 101 e.g. PH for celll.

Power headroom reporting may be used by the UE 101 to inform the serving network node such as satellite 102 or BS 104 about the power usage, i.e. amount of transmission power available at the UE 101. This information is later used by the scheduler in the network node 102 or 104 to allocate or adapt the transmission parameters used by the UE 101 for uplink transmission in the cell 110, e.g. modulation scheme, coding rate, and resources. The network node such as satellite 102 or BS 104 may further decide, based on the received PHR, whether to schedule the UE 101 or not e.g. in the next one or more uplink time resources. For example, if the PH value is below a certain threshold then the network node such as satellite 102 or BS 104 may decide not to schedule the UE 101 (e.g. due to insufficient UE available power); otherwise the network node such as satellite 102 or BS 104 may decide to schedule the UE 101 in the UL (e.g. if there is UL data for transmission).

The value of PH(i) can be either negative or positive. A negative value indicates to the network node such as satellite 102 or BS 104 that it has received an uplink resource grant which would require more transmission power than the UE 101 has available, e.g. serving network node such as satellite 102 or BS 104 has scheduled this UE with a data rate higher than what the UE 101 can handle, i.e. UE 101 is limited by PCMAX.C )- The network node such as satellite 102 or BS 104 has the possibility to adapt the scheduling grant based on the received PHR information. It is therefore important for the UE to correctly or more accurately report the actual or predicted usage of the power headroom. A positive value on the other hand means that the UE 101 has power left, i.e. it is not using the maximum power and/or can handle a higher data rate that what is currently scheduled with.

In principle, the PHR may be sent in any time resource (e.g. slot, subframe) in which the UE 101 has an uplink grant. In the case of NB-IoT, the NB-IoT UE may report the power headroom information using the message 3 (Msg3) in a random access procedure, by using 2-bits for the lowest configured NB-PRACH repetition level. This means that 4 different values may be reported compared to 64 values with the legacy LTE UE.

The NB-IoT UE in an NTN may be served by different types of satellites 102 that have different characteristics (e.g. altitudes, speed, orbits, etc.). This leads to different angle of horizon between the UE 101 and the satellite 102, different radio channel characteristics, link budget etc., based on the type of the satellite 102. For example, different types of satellite 102 may result in different signal strength (e.g. RSRP, NRSR, pathloss (PL) etc.) between the UE 101 and the satellite 102; whose signal strength difference may be very large due to the altitudes of the different types of satellites 102. In one example, it is assumed that higher pathloss (i.e., more variation) may be observed in cells served by a LEO or MEO satellite compared to cells served by a GEO satellite. Furthermore, in case of the GEO satellite, the variation may be relatively smaller. In another example, it is assumed that a UE served by cell 1 managed by a GEO would require more uplink resources since GEO is operating at much higher altitudes than LEO or MEO. Therefore, it would require more uplink repetitions in order to reach the GEO satellite which leads to more power consumptions.

The example in formula (1) shows that the power headroom calculation may depend on the PL, and considering that only 4 values can be reported for NB-IoT UE. The UE 101 can be served by different types of satellites 102 with different characteristics. As a result, the legacy PHR (e.g. legacy LTE PHR or LTE based NB-IoT PHR) reporting configuration may not be feasible or optimal. The PHR based on the legacy approach may lead to inefficient allocation of resources for UL transmission.

According to the methods disclosed in this disclosure, the UE 101 may determine one PHR configuration out of at least two possible configurations for reporting the determined or predicted power headroom, where the determination is based on the type of satellite 102 serving or managing cell 110 (i.e., cell 1 ).

By selecting a PHR reporting configuration based on the type of satellite 102 serving or managing the serving cell 110 (e.g. celll), the reported values (e.g. range and resolution) may be adapted to the operating scenario and the reported values may become more reliable.

Alternatively, the UE 101 may further indicate the configuration index (i.e., the index for the used PHR configuration), such as 1 additional bit indicator, on which it is used to report the PHR, if the estimated PHR’s cell is different from the cell to which the PHR is to be transmitted.

In an example, when the serving satellite 102 is of type LEO then it is more relevant or important to have higher reporting resolution/granularity in the lower reporting range (negative values) of the PHR reporting values since the UE 101 may be experiencing more pathloss variation compared to being served by a GEO satellite. In order to compensate for the fast moving satellites and/or higher pathloss, the UE 101 may therefore be using e.g. higher transmission power, more repetitions. Therefore, by using reporting configuration with higher reporting resolution in the negative range, the embodiment may allow the UE 101 to report more accurate values of the predicted power usage in the UE 101. In this case, the UE 101 may select PHR reporting configuration comprising of K possible reportable values in the reporting range as shown in a general example in Table 2.

Table 2: Power headroom report mapping for UE served by NGSO (e.g. LEO) satellite comprising of K number of reportable values

In an example, when the serving satellite 102 is of type GEO then it is more relevant to have higher reporting resolution/granularity in the higher reporting range (positive values) since the satellite 102 is more stationary compared to e.g. LEO or MEO and the UE 101 may not be experiencing higher pathloss variation compared to being served by a LEO or MEO. Because of the geostationary position of the GEO satellites, it can be assumed that the UE is in good coverage and it may not always be necessary to use the maximum power, or the highest repetitions compared to being served by a fast moving satellite such as LEO. Therefore, it is reasonable to assume that the predicted power headroom, PH(i), is often positive, and thus better resolution/ranges on the positive values are desired. In this case, the UE 101 may select PHR reporting configuration comprising of K possible reportable values in the reporting range, as shown in a general example in Table 3.

Table 3: Power headroom report mapping for UE served by GSO (e.g. GEO) satellite comprising of K number of reportable values

In an example, when the serving satellite 102 is of type GEO it may be useful to select a PHR reporting configuration that allows the UE 101 to report more values and/or values with higher resolutions/ranges in the negative range. This is because a geostationary satellite (e.g. GEO) is operating at significantly higher altitude compared to a non-geostationary satellite (e.g. LEO). Therefore, higher pathloss variation may be expected with GEO which may be compensated by the applying higher uplink transmission power and more repetitions. Consequently, the predicted power headroom, PH(i), is often negative and thus more accurate resolutions and ranges on the negative values are desired. In this case, in one example when the cell 110 is served by NGSO satellite, then the UE 101 may select PHR reporting configuration as shown in Table 2. But when the cell 110 is served by GSO satellite, then the UE 101 may select PHR reporting configuration as shown in Table 3.

In an example, when the satellite 102 serving the cell 110 (e.g. celll) is of type LEO, the PHR configuration comprising of 4 reportable values may be shown in table 4.

Table 4: Power headroom report mapping for UE served by NGSO (e.g. LEO) satellite comprising 4 reportable values

In an example, when the satellite 102 serving the cell 110 (e.g. celll) is of type GEO, the PHR configuration comprising of 4 reportable values may be shown in table 5.

Table 5: Power headroom report mapping for UE served by GSO (e.g. GEO) satellite comprising of 4 number of reportable values

The reporting configurations in Tables 2 and 3 may differ in terms of reporting resolutions and/or ranges and/or maximum reportable value and/or minimum reportable value. Similarly, the reporting configurations in Tables 4 and 5 also may differ in terms of reporting resolutions and/or ranges and/or maximum reportable value and/or minimum reportable value.

In an example, it may be assumed that the maximum reportable value in Table 3 may be higher than the maximum reportable value in Table 2, i.e. NK’>NK.

In an example, the minimum reportable value in Table 2 may be lower than the minimum reportable value in Table 3, i.e. N1 < N1’.

In an example, the difference between Tables 2 and 3 may be that Table 2 has more negative reportable values compared to Table 3. Therefore, the resolution or granularity of the reportable negative values may be assumed to be higher in Table 2 than in Table 3. The resolution or granularity of the positive reportable values in Table 2 may be assumed to be lower than in Table 3, but with the same power headroom.

In an example, the difference between Tables 2 and 3 may be that Table 2 has more negative reportable values compared to Table 3. Therefore, the resolution or granularity of the reportable negative values may be assumed to be higher in Table 2 than in Table 3. The power headroom of the positive reportable values in Table 2 may be assumed to be lower than in Table 3, but with the same power resolution or granularity.

In an example, the resolution or granularity of the reportable positive values may be assumed to be higher in Table 3 than Table 2. Therefore, the resolution or granularity of the reportable negative values may be assumed to be lower in Table 3 than in Table 2.

In an example, the resolution or granularity of the reportable positive values may be assumed to be higher in Table 3 than Table 2. Therefore, the negative power limit values may be assumed to be larger in Table 3 than in Table 2.

Examples of PHR reporting configuration for NB-IoT for UE power class 3 and 5 for normal coverage:

The example in Table 6 shows the PHR reporting configuration when enhanced coverage level 0 (also called as normal coverage) is selected and the serving cell (e.g. celll) for which the PH is reported is served or managed by a LEO satellite.

Table 6: Power headroom report mapping for UE category NB1 UEs for a cell (e.g. cell 1 ) served by LEO satellite during random access procedure

The example in Table 7 shows the PHR reporting configuration when enhanced coverage level 0 (also called as normal coverage) is selected and the serving cell (e.g. celll) for which the PH is reported is served or managed by a GEO satellite.

Table 7: Power headroom report mapping for UE category NB1 UEs for a cell (e.g. celll) served by GEO satellite during random access procedure

Another example in Table 8 shows the PHR reporting configuration when enhanced coverage level 0 (also called as normal coverage) is selected and the serving cell (e.g. celll) for which the PH is reported is served or managed by a LEO satellite.

Table 8: Power headroom report mapping for UE category NB1 UEs for a cell (e.g. celll) served by LEO satellite during random access procedure

The example in Table 9 shows the PHR reporting configuration when enhanced coverage level 0 (also called as normal coverage) is selected and the serving cell (e.g. celll) for which the PH is reported is served or managed by a GEO satellite.

Table 9: Power headroom report mapping for UE category NB1 UEs for a cell (e.g. celll) served by GEO satellite during random access procedure

Examples of PHR reporting configuration for NB-IoT for UE power class 3 and 5 for enhanced coverage

Example in Table 10 shows the PHR reporting configuration when enhanced coverage level other than 0 (also called as enhanced coverage) is selected and the serving cell is served or managed by a LEO satellite.

Table 10: Power headroom report mapping for UE category NB1 UEs not supporting enhanced PHR when the enhanced coverage level other than 0 is selected during random access procedure and UE is served by LEO satellite

The example in Table 11 shows the PHR reporting configuration when enhanced coverage level other than 0 (also called as enhanced coverage) is selected and the serving cell is served or managed by a GEO satellite.

Table 11: Power headroom report mapping for UE category NB1 UEs not supporting enhanced PHR when the enhanced coverage level other than 0 is selected during random access procedure and UE is served by GEO satellite

The step of determining of PHR configuration to be used by the UE 101 for reporting the PHR results to a network node such as satellite 102 or BS 104 may comprise, e.g., one or more of: • Determining based on a pre-defined rule. For example, assuming that the serving or measured cell 110 is served by different types of satellites 102, it is assumed that each satellite type is associated with a reporting configuration. For example, if celll is served by a LEO satellite, then the UE may use a first PHR reporting configuration. But if celll is served by a MEO satellite, then the UE 101 may use a second PHR reporting configuration. Similarly, if celll is served by GEO then the UE 101 may use a third PHR reporting configuration. The association between the satellite type and PHR reporting configuration is assumed to be predefined in this example.

• A message or indicator received from another node (e.g., a network node).

• Determining based on a value or using a value received from another node (e.g., a network node).

• Determining based on history or stored information.

Step S304: Reporting of measurement result to a serving node using determined PHR configuration

In this step, the UE 101 may transmit the PHR (i.e., reported value) based on the determined PHR report mapping to a network node such as satellite 102 or BS 104 e.g. NW1. The UE 101 may report or transmit the results of the estimated PH using the determined PHR to the network node such as satellite 102 or BS 104 using one or more of the following mechanisms:

• periodically, e.g. every T1 time period. The periodicity of the PHR can be configured by NWl.

• aperiodically, e.g. transmitting once or few times. For example, the PH is estimated and transmitted by the UE 101 in response to receiving a request or message from NW1.

• Based on one or more triggering conditions or fulfillment of the criteria, which can be pre-defined or configured by NW1. Examples of criteria are: o If the estimated PH changes by certain margin e.g. increases by certain margin (Ml), decreases by certain margin (M2) etc. o If the estimated PH becomes larger than certain threshold (Hl), o If the estimated PH becomes smaller than certain threshold (H2), o If the estimated PH is not within a set of thresholds, H3 and H4, o Based on the configuration of the ephemeris data for the cell (e.g. celll) on which the PH is estimated e.g.

□ If the UE has received new ephemeris data for the cell,

□ If the ephemeris data for the cell has expired or is no more valid. Alternatively, the UE 101 may further transmit the PHR table indicator to indicate the specific PHR table used by the UE 101, when the UE 101 transmits the PHR. In one example, the cell for which the PHR is calculated (e.g. NW2) is different from the target cell to which the PHR is to be reported (e.g. NW1).

The UE 101 may receive information about the scheduling resources (e.g. uplink grant) from a network node such as satellite 102 or BS 104 (e.g. NW1) for transmitting UL signals in the cell 110 for which the UE has transmitted the PH. The UE 101 may further use the allocated/configured UL resources for performing one or more of the following procedures or operational tasks:

• Sending a control channel to celll e.g. PUCCH or MPUCCH

• Sending a data channel to celll e.g. PUSCH

• Sending a random access related signal to celll e.g. PRACH, preamble etc.

• Sending S RS to celll.

With the embodiments herein, the PHR configuration may be adapted to the operating scenario, and thus the embodiments may allow the UE (for example the low complexity and low cost UE) to report more accurate information about the actual power usage in the UE. As a result, the network side may adapt the uplink transmission parameters for the UE based on the actual reported PHR information.

In some embodiments herein, the PHR may be adapted to link budget of satellite serving the UE. This in turn may allow more accurate PHR regardless of the type of satellite and/or orbit used by the satellite serving the cell on which the PH is reported.

Figure 4 is a schematic block diagram showing an example UE 101, according to the embodiments herein.

In an embodiment, the UE 101 may include at least one processor 401; and a non-transitory computer readable medium 402 coupled to the at least one processor 401. The non-transitory computer readable medium 402 may store instructions executable by the at least one processor 401, whereby the at least one processor 401 is configured to perform the steps in one of the example methods 300 and 320 as shown in the schematic flow charts of Figures 3 A and 3B; however, the details relating to Figure 3 A are omitted here for brevity.

Referring again to Figure 3B and the description above, the UE 101 and/or the at least one processor 401 of Figure 4, to perform the method 320 of Figure 3B, is configured to estimate a PH value as a measured quantity value for a cell 110. The cell 110 is managed by, or operated by, an NTN node 102. At least one of the NTN node 102 and the network node serving the UE 101 may be one of: a satellite node or a satellite access node (SAN), a high altitude platform BS (HAPS), or a drone base station. The network node serving the UE 101 may be an earth based network node, such as a base station (BS) 104 on the ground. The UE 101 may be a Narrow Band Internet of Things, NB-IoT, device. The UE 101 may be configured to be operated in a normal coverage mode or in an enhanced coverage mode. The normal coverage mode may include coverage enhancement (CE) mode 0 (also denoted CE level # 0 (CEO)), and the enhanced coverage mode may include CE mode 1, CE mode 2, and CE mode 3 (also denoted CE level # 1 (CE1), CE level # 2 (CE2), CE level # 3 (CE3), respectively).

The UE 101 and/or the at least one processor 401 is further configured to select, out of at least two PHR mapping tables, a PHR mapping table for the reporting based on a type of the NTN node 102 and to select a reported PH value from the selected PHR mapping table based on the measured quantity value for the cell 110. The UE 101 and/or the at least one processor 401 may be configured to select a first PHR mapping table when the type of the NTN node is a first type, and to select a second PHR mapping table when the type of the NTN node is a second type, out of the at least two PHR mapping tables. The first and second PHR mapping tables may differ in terms of at least one of: a reporting resolution, a reporting range, a maximum reportable value, a minimum reportable value. In one example, the maximum reportable value of the second PHR mapping table may be higher than the maximum reportable value of the first PHR mapping table. In another example, the reporting resolution for negative reportable values of the first PHR mapping table may be higher than the reporting resolution for negative reportable values of the second PHR mapping table and reporting resolution for positive reportable values of the first PHR mapping table may be lower than the reporting resolution for positive reportable values of the second PHR mapping table. In yet another example, the reporting resolution for negative reportable values of the first PHR mapping table may be higher than the reporting resolution for negative reportable values of the second PHR mapping table and the reporting range for positive reportable values of the first PHR mapping table may be lower than the reporting range for positive reportable values of the second PHR mapping table. In one example, the selected PHR mapping table may include 4 selectable reported values, in which: a reported value POWER HEADROOM O may be used for reporting a measured quantity value greater than or equal to -54 dB and less than 5 dB, a reported value POWER HEADROOM 1 may be used for reporting a measured quantity value greater than or equal to 5 dB and less than 8 dB, a reported value POWER HEADROOM 2 may be used for reporting a measured quantity value greater than or equal to 8 dB and less than 11 dB, and a reported value POWER HEADROOM 3 may be used for reporting a measured quantity value greater than or equal to lldB. In another example, the selected PHR mapping table may include 4 selectable reported values, in which: a reported value POWER HEADROOM O may be used for reporting a measured quantity value greater than or equal to -54 dB and less than -10 dB, a reported value POWER HEADROOM 1 may be used for reporting a measured quantity value greater than or equal to -10 dB and less than -2 dB, a reported value POWER HEADROOM 2 may be used for reporting a measured quantity value greater than or equal to -2 dB and less than 6 dB, and a reported value POWER HEADROOM 3 may be used for reporting a measured quantity value greater than or equal to 6 dB.

In some example embodiments, the first type may be GSO, such as GEO satellite type, and the second type may be NGSO, such as one of LEO satellite type and MEO satellite type. In other example embodiments the first type may be NGSO, such as one of LEO and MEO satellite types, and the second type may be GSO, such as GEO satellite type.

The UE 101 and/or the at least one processor 401 is then configured to transmit the selected reported PH value to a network node serving the UE 101. The UE 101 and/or the at least one processor 401 may be configured to transmit the reported PH value by using 2-bits within message 3, (Msg3), in a random access procedure. The UE 101 and/or the at least one processor 401 may further be configured to indicate an index of the selected PHR mapping table by using an additional 1 -bit indicator, or be configured to indicate a PHR table indicator to indicate the PHR mapping table used by the UE 101.

The network node serving the UE 101 may be the NTN node 102 serving the UE in the cell 110, or a BS 104 serving the UE in the cell 110 and being connected to the NTN node 102 via a gateway 103, or a second network node serving the UE in a second cell that is different from the cell 110. The cell 110 may be a Primary Cell, P-Cell, for the UE 101 and the second cell may be a Secondary Cell, S-Cell, for the UE 101. Alternatively, the cell 110 may be an S-Cell for the UE 101 and the second cell may be a P-Cell for the UE 101.

Note that, the UE 101 may be implemented as hardware, software, firmware and any combination thereof. For example, the UE 101 may include a plurality of units, circuitries, modules or the like, each of which may be used to perform one or more steps of the example method 300 or 320.

Figure 5 is a schematic block diagram showing an example computer-implemented apparatus 500, according to the embodiments herein. In an embodiment, the apparatus 500 may be configured as the above mentioned apparatus, such as the UE 101.

In an embodiment, the apparatus 500 may include but not limited to at least one processor such as Central Processing Unit (CPU) 501, a computer-readable medium 502, and a memory 503. The memory 503 may comprise a volatile (e.g., Random Access Memory, RAM) and/or non-volatile memory (e.g., a hard disk or flash memory). In an embodiment, the computer-readable medium 502 may be configured to store a computer program and/or instructions, which, when executed by the processor 501, causes the processor 501 to carry out any of the above mentioned methods 300, 320.

In an embodiment, the computer-readable medium 502 (such as non-transitory computer readable medium) may be stored in the memory 503. In another embodiment, the computer program may be stored in a remote location for example computer program product 504 (also may be embodied as computer-readable medium), and accessible by the processor 501 via for example carrier 505.

The computer-readable medium 502 and/or the computer program product 504 may be distributed and/or stored on a removable computer-readable medium, e.g. diskette, CD (Compact Disk), DVD (Digital Video Disk), flash or similar removable memory media (e.g. compact flash, SD (secure digital), memory stick, mini SD card, MMC multimedia card, smart media), HD-DVD (High Definition DVD), or Blu-ray DVD, USB (Universal Serial Bus) based removable memory media, magnetic tape media, optical storage media, magneto-optical media, bubble memory, or distributed as a propagated signal via a network (e.g. Ethernet, ATM, ISDN, PSTN, X.25, Internet, Local Area Network (LAN), or similar networks capable of transporting data packets to the infrastructure node).

Example embodiments are described herein with reference to block diagrams and/or flowchart illustrations of computer-implemented methods, apparatus (systems and/or devices) and/or non-transitory computer program products. It is understood that a block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, may be implemented by computer program instructions that are performed by one or more computer circuits. These computer program instructions may be provided to a processor circuit of a general purpose computer circuit, special purpose computer circuit, and/or other programmable data processing circuit to produce a machine, such that the instructions, which execute via the processor of the computer and/or other programmable data processing apparatus, transform and control transistors, values stored in memory locations, and other hardware components within such circuitry to implement the functions/ acts specified in the block diagrams and/or flowchart block or blocks, and thereby create means (functionality) and/or structure for implementing the functions/acts specified in the block diagrams and/or flowchart block(s).

These computer program instructions may also be stored in a tangible computer-readable medium that may direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instructions which implement the functions/acts specified in the block diagrams and/or flowchart block or blocks. Accordingly, embodiments of present inventive concepts may be embodied in hardware and/or in software (including firmware, resident software, micro-code, etc.) that runs on a processor such as a digital signal processor, which may collectively be referred to as “circuitry,” “a module” or variants thereof.

It should also be noted that in some alternate implementations, the functions/acts noted in the blocks may occur out of the order noted in the flowcharts. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality /acts involved. Moreover, the functionality of a given block of the flowcharts and/or block diagrams may be separated into multiple blocks and/or the functionality of two or more blocks of the flowcharts and/or block diagrams may be at least partially integrated. Finally, other blocks may be added/inserted between the blocks that are illustrated, and/or blocks/operations may be omitted without departing from the scope of inventive concepts. Moreover, although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

Many variations and modifications can be made to the embodiments without substantially departing from the principles of the present inventive concepts. All such variations and modifications are intended to be included herein within the scope of present inventive concepts. Accordingly, the above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended examples of embodiments are intended to cover all such modifications, enhancements, and other embodiments, which fall within the spirit and scope of present inventive concepts. Thus, to the maximum extent allowed by law, the scope of present inventive concepts are to be determined by the broadest permissible interpretation of the present disclosure including the following examples of embodiments and their equivalents, and shall not be restricted or limited by the foregoing detailed description.

Abbreviations

3GPP 3rd Generation Partnership Project 5G 5th Generation

BS Base Station

CA Carrier aggregation

CHO Conditional Handover

DC Dual connectivity eNB Evolved NodeB (LTE base station)

GEO Geostationary Orbit gNB Base station in NR.

GNSS Global Navigation Satellite System

HO Handover

LEO Low Earth Orbit

LTE Long Term Evolution

MAC Medium Access Control

NB-IoT Narrow Band Internet of Things

NR New Radio

NTN Non-Terrestrial Network

NW Network

PCell Primary Cell

PHR Power Headroom Reporting

PSCell Primary SCell

RAT Radio Access Technology

RRC Radio Resource Control

RRM Radio Resource Management

RS Reference Signal

RSRP Reference Signal Received Power

SCell Secondary Cell

SMTC SSB Measurement Timing Configuration

SNR Signal to noise ratio

UE User Equipment.