WO2023126800A1

WO2023126800A1 - Adaptive reference signal configuration (rsc) selection

Info

Publication number: WO2023126800A1
Application number: PCT/IB2022/062701
Authority: WO
Inventors: Ming Li; Muhammad Ali Kazmi; Johan Rune
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2022-01-03
Filing date: 2022-12-22
Publication date: 2023-07-06

Abstract

A method (500) performed by a UE. The method includes obtaining information identifying N reference signal configuration, RSC, sets, wherein N > 1 and each RSC set comprises one or more reference signal configurations, RSCs. The method also includes selecting M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N. The method also includes using at least one of the selected M RSC sets to perform one or more tasks.

Description

ADAPTIVE REFERENCE SIGNAL CONFIGURATION (RSC) SELECTION

TECHNICAL FIELD

[001] Disclosed are embodiments related to the adaptive selection of one or more reference signal configurations (RSCs).

BACKGROUND

[002] There is an ongoing resurgence of satellite communications. For example, several plans for satellite networks have been announced in the past few years. Satellite networks can complement terrestrial mobile networks by providing connectivity to underserved areas and providing multicast and/or broadcast services.

[003] Adapting conventional, terrestrial wireless access technologies, including Long

Term Evolution (LTE) and New Radio (NR), to work well with satellite networks is drawing significant interest, which is reflected in standardization work performed by the 3rd Generation Partnership Project (3 GPP).

[004] In 3GPP Release 15, the first release of the Fifth Generation (5G) system (5GS) was specified. This is a new radio access technology (RAT) intended to serve may use cases, such as, for example, enhanced mobile broadband (eMBB), ultra-reliable and low latency communication (URLLC), and massive machine-type-communications (mMTC). 5G includes the NR access stratum interface and the 5G Core Network (5GC). The NR physical and higher layers reuse parts of the LTE specification, and to that add needed components when motivated by new use cases. One such component is the introduction of a sophisticated framework for beam forming and beam management to extend the support of the 3 GPP technologies to a frequency range going beyond 6 GHz.

[005] In Release 15, 3 GPP started the work to prepare NR for operation in a Non¬

Terrestrial Network (NTN). The work was performed within the study item “NR to support NonTerrestrial Networks” and resulted in 3GPP Technical Report (TR) 38.811 V15.4.0. In 3GPP Release 17 (Rel-17), there is ongoing related work item, “Solutions for NR to support nonterrestrial networks”, 3GPP document, RP-213691. [006] Characteristics of Satellite Radio Access Network

[007] Depending on the orbit altitude, a satellite may be categorized as low earth orbit

(LEO), medium earth orbit (MEO), or geostationary earth orbit (GEO) satellite. For LEO, typical heights range from 250 to 1,500 km, with orbital periods ranging from 90 to 120 minutes; for MEO typical heights range from 5,000 to 25,000 km, with orbital periods ranging from 3 to 15 hours; and for GEO the height is about 35,786 km, with an orbital period of 24 hours.

[008] Two basic architectures can be distinguished for satellite communication networks, depending on the functionality of the satellites in the system.

[009] The first is referred to as “Transparent payload” (also referred to as bent pipe architecture). In this 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 3 GPP 5G architecture and terminology, the transparent payload architecture means that the 5G base station (gNB) is located on the ground and the satellite forwards signals/data between the gNB and the UE.

[0010] The second is referred to as “Regenerative payload.” In this architecture, 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 3 GPP architecture and terminology, the regenerative payload architecture means that the gNB is located in the satellite.

[0011] In the work item for NRNTN in 3 GPP Rel-17, only the transparent payload architecture is considered.

[0012] A satellite network or satellite based mobile network may also be called a nonterrestrial network (NTN). On the other hand mobile network with base stations on the group 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.

[0013] 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, but cells consisting of the coverage footprint of multiple beams are not excluded in the 3 GPP work. The footprint of a beam is also often referred to as a spotbeam. 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 (where the latter may be referred to as quasi-earth-fixed beams or quasi- earth-fixed cells). The size of a spotbeam depends on the system design, which may range from tens of kilometers to a few thousands of kilometers.

[0014] 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.

[0015] A 3GPP UE may be in a RRC IDLE or RRC INACTTVE state. When such a UE is in such a state the UE required to perform number of procedures including, for example, measurements for mobility purposes, paging monitoring, logging measurement results, tracking area update, and search for a new Public Land Mobile Network (PLMN) to mention a few. These procedures will consume power, and a general trend in 3 GPP has been to allow for relaxation of these procedures to prolong the UE’s battery life. This trend has been especially pronounced for loT devices supported by reduced capability (redcap), NB-IoT and LTE-M.

[0016] 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.

[0017] The distance between the UE and a satellite can vary significantly, depending on the position of the satellite and thus the elevation angle s seen by the UE. Assuming circular orbits, the minimum distance is realized when the satellite is directly above the UE (s = 90°), and the maximum distance when the satellite is at the smallest possible elevation angle. Table 1 shows the distances between satellite and UE 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

[0018] 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 to 100 ps every second, depending on the orbit altitude and satellite velocity.

[0019] Ephemeris data

[0020] In 3 GPP TR 38.821 , it has been noted that ephemeris data should be provided to the UE, for example to assist with pointing a directional antenna (or an antenna beam) towards the satellite. A UE knowing its own position (e.g., via 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).

[0021] 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, s, i, Q, 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 Q, 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).

[0022] A two-hne 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 M instead of a and t.

[0023] A completely different set of parameters is the position and velocity vector (x, y, z, vx, vy, vz) of a satellite. 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.

[0024] SSB-MTC and measurement gaps

[0025] The NR synchronization signal (SS) consists of a primary SS (PSS) and secondary SS (SSS). The NR physical broadcast channel (PBCH) carries basic system information. The combination of SS and PBCH is referred to as Synchronization Signal Block (SSB) in NR. Multiple SSBs are transmitted in a localized burst set. Within an SS burst set, multiple SSBs can be transmitted in different beams. The transmission of SSBs within a localized burst set is confined to a 5 ms window. The set of possible SSB time locations within an SS burst set depends on the numerology which in most cases is uniquely identified by the frequency band. The SSB periodicity can be configured from the value set {5, 10, 20, 40, 80, 160} ms (where the unit used in the configuration is subframe, which has a duration of 1 ms).

[0026] A UE does not need to perform measurements with the same periodicity as the SSB periodicity. Accordingly, the SSB measurement time configuration (SMTC) has been introduced for NR. The signaling of SMTC window informs the UE of the timing and periodicity of SSBs that the UE can use for measurements. The SMTC window periodicity can be configured from the value set {5, 10, 20, 40, 80, 160} ms, matching the possible SSB periodicities. The SMTC window duration can be configured from the value set {1, 2, 3, 4, 5} ms (where the unit used in the configuration is subframe, which has a duration of 1 ms). The SMTC window duration may also be simply called as SMTC duration or SMTC length or SMTC occasion duration or SMTC occasion length etc. [0027] The UE may use the same RF module for measurements of neighboring cells and data transmission in the serving cell. Measurement gaps allow the UE to suspend the data transmission in the serving cell and perform the measurements of neighboring cells. The measurement gap repetition periodicity can be configured from the value set {20, 40, 80, 160} ms, the gap length can be configured from the value set {1.5, 3, 3.5, 4, 5.5, 6, 10, 20} ms. Usually, the measurement gap length is configured to be larger than the SMTC window duration to allow for RF retuning time. Measurement gap time advance is also introduced to fine tune the relative position of the measurement gap with respect to the SMTC window. The measurement gap timing advance can be configured from the value set {0, 0.25, 0.5} ms. FIG. 1 provides an illustration of SSB, SMTC window, and measurement gap. [0028] For NR, the different variants of SMTC (SSB-MTC, SSB-MTC2 and SSB-

MTC3) that are currently specified are defined as shown in Table 2 in ASN. 1 code in 3 GPP TS 38.331 version 16.6.0.

TABLE 2

[0029] Note that SSB-MTC3 is defined to be used only by integrated access backhaul

(IAB) nodes, but it has been proposed that SSB-MTC3 could be reused for NTN UEs.

SUMMARY [0030] Certain challenges presently exist. For example, satellite movement (resulting in moving cells or switching cells) and long propagation delays are challenges that need to be addressed in an NTN. The default assumption in terrestrial network design (e g., NR or LTE) is that cells are stationary, but this is not the case in NTN, especially when LEO satellites are considered. A LEO satellite may be visible to a UE on the ground only for a few seconds or minutes. There are two different options for LEO deployment. The beam/cell coverage is fixed with respect to a geographical location with earth-fixed beams (which may be referred to as quasi- earth-fixed beams or quasi-earth-fixed cells), i.e., steerable beams from satellites ensure that a certain beam covers the same geographical area even as the satellite moves in relation to the surface of the earth. On the other hand, with moving beams a LEO satellite has fixed antenna pointing direction in relation to the earth’s surface (e.g., perpendicular to the earth’s surface) and thus cell/beam coverage sweeps the earth as the satellite moves. In that case, the spotbeam, which is serving the UE, may switch every few seconds.

[0031] The propagation delays in terrestrial mobile systems are usually less than 1 millisecond; in contrast, the propagation delays in NTN can be much longer, ranging from several milliseconds (LEO) to hundreds of milliseconds (GEO) depending on the altitudes of the spaceborne or airborne platforms deployed in the NTN.

[0032] Depending on the deployment it is also possible that there is a large number of occasional satellite coverage fully overlapping or partially overlapping between coverage of different satellites. Typically, a device camping on a network expects continuous network availability. This is in contrast to camping on a network where radio access network associated with satellites (e.g., LEO, MEO or GEO) is moving and not providing carefully designed coverage like cell configuration in terrestrial network. Long propagation delays also aggravate UE’s measurement load because measurement needs to cover the wide range of propagation delays from different satellites.

[0033] Furthermore, a network node may configure M SMTCs in one measurement object (MO), but not all UEs allow measurements on all M SMTCs in one occasion or periodicity; instead, from 1 to M possibly due to some reasons such as capacity limitation on SMTC number, SMTC configurations limitation, measurement limitation, power saving, no/inaccurate UE position, no/inaccurate satellite ephemeris data and so on. The problem is more acute when the UE is in RRC_IDLE/INACTIVE state. In this case, SMTC configurations are cell specific and broadcasted by a network node (i.e., SMTC configurations cannot be signaled for a specific UE). Enhancements in terms of the trade-off between flexibility and simplicity are therefore necessary. Furthermore, some of the explicit details or methods for the realization of the configuration are lacking.

[0034] Accordingly, in one aspect there is provided a method performed by a UE. The method includes obtaining information identifying N RSC sets (N > 1), where each RSC set comprises one or more RSCs. For example, in one embodiment, the received information identifies N RSCs and in another embodiment the received information identified N groups of RSCs. The method also includes selecting M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N. The method also includes using at least one of the selected M RSC sets to perform one or more tasks.

[0035] There is also provided a computer program comprising instructions which when executed by processing circuitry of a UE causes the UE to perform the UE methods disclosed herein. In one embodiment, there is provided a carrier containing the computer program wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium. There is also provided a UE configured to perform any of the UE methods disclosed herein. The UE may include processing circuitry and a memory containing instructions executable by the processing circuitry whereby the UE is configured to perform any one of the UE methods disclosed herein.

[0036] In another aspect there is provided a method performed by a network node. The method includes transmitting information identifying N reference signal configuration, RSC, sets, wherein N > 1 and each RSC set comprises one or more reference signal configurations, RSCs. The method also includes transmitting information for enabling a UE to select M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N.

[0037] There is also provided a computer program comprising instructions which when executed by processing circuitry of a network node causes the network node to perform the network node methods disclosed herein. In one embodiment, there is provided a carrier containing the computer program wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium. There is also provided a network node configured to perform any of the network node methods disclosed herein. The network node may include processing circuitry and a memory containing instructions executable by the processing circuitry whereby the network node is configured to perform any one of the network node methods disclosed herein. [0038] The embodiments disclosed herein provide several advantages. For example, the embodiments enable a UE to select the most optimal or preferred reference signal configurations (RSCs) (e.g., SMTCs) from a plurality of configured RSCs.

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments.

[0040] FIG. 1 illustrates SSB, SMTC window, and measurement gap.

[0041] FIG. 2 illustrates a NTN according to an embodiment.

[0042] FIG. 3 shows an example where 4 RSCs per MO or per frequency layer are transmitted/configured in a cell.

[0043] FIG. 4A illustrates four simultaneous non-overlapping RSCs.

[0044] FIG. 4B illustrates two overlapping RSCs.

[0045] FIG. 5 is a flowchart illustrating a process according to some embodiments.

[0046] FIG. 6 is a flowchart illustrating a process according to some embodiments.

[0047] FIG. 7 is a block diagram of a UE according to some embodiments.

[0048] FIG. 8 is a block diagram of a network node according to some embodiments.

DETAILED DESCRIPTION

[0049] Terminology

[0050] The time period over which a UE can maintain connection, or can camp on, or can maintain communication, and so on to a gNB (e.g., a gNB carried by a satellite) is referred to as “coverage time” or “serving time” or “network availability” or “sojourn time” or “dwell time” etc. The term “Non-coverage time” (a.k.a., “non-serving time” or “network unavailability” or “non-sojourn time” or “non-dwell time”) refers to a period of time during which a gNB cannot serve or communicate or provide coverage to a UE. Another way to interpret the availability is that it is not about a gNB not being able to serve the UE due to lack of coverage, but rather the UE does not need to measure on certain cells which are “not likely to become the serving cell of the UE.” The UE may determine this based on, for example, ephemeris data broadcasted by the serving satellite. In this case, the terminology may still be as in no coverage case or it may be different (e.g., “no need to measure”).

[0051] As used herein, a “node” can be a network node or a UE. An example of a network node is a base station (e.g., gNB), multi-standard radio (MSR) radio node, 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), remote radio unit (RRU), remote radio head (RRH) nodes in distributed antenna system (DAS), core network node, etc.

[0052] The term “UE” refers to any type of device capable of wirelessly communicating with a network node and/or with another UE. Examples of UE are target device, device to device (D2D) UE, vehicular to vehicular (V2V), machine type UE, machine type communication (MTC) UE or UE capable of machine to machine (M2M) communication, personal digital assistant (PDA), tablet, mobile terminals, smart phone, laptop embedded equipment (LEE), laptop mounted equipment (LME), dongles, etc.

[0053] The term signal or radio signal used herein can be any physical signal or physical channel. Examples of downlink (DL) physical signals are reference signals (RSs) such as PSS, SSS, channel state information (CSI) RS (CSLRS), demodulation RS (DMRS) signals in SS/PBCH block (SSB), discovery reference signal (DRS), etc. An 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. A UE is configured with information about SSB on cells of certain carrier frequency by one or more SS/PBCH block measurement timing configurations (SMTCs). The SMTC comprises parameters such as SMTC periodicity, SMTC occasion length in time or duration, SMTC time offset wrt 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 sounding reference signal (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 Physical Broadcast Channel (PBCH), Physical DL Control Channel (PDCCH), Physical DL Shared Channel (PDSCH), etc.

[0054] FIG. 2 illustrates an example NTN. As shown in FIG. 2, the example NTN includes the following components: a satellite 202, a UE 212, and an earth-based gateway 204 that connects the satellite to a network node 206 (e.g., a base station) (or connects the satellite to a core network if the satellite carries the network node 206). The link 208 between gateway 204 and satellite 202 is referred to as the feeder link 208 and the link 210 between satellite 202 and UE 212 is referred to as the access link 210 (a.k.a., service link 210). In this scenario, UE 212 is located within a first cell 214, which is managed or served by network node 206. UE 212 may be configured to perform one or more measurements on signals (e.g. reference signals (RSs)) of one or more cells belong to one or more carrier frequencies. The UE may receive signals (e.g. RS) that are transmitted by satellite 202.

[0055] This disclosure describes a process for UE 212 to adaptively select a set of one or more reference signal configurations (RSCs) (e.g., select a single RSC or a group of RSCs) based on certain criteria (i.e., a set of a set of one or more selection criterions). In one use case, a network node transmits information about at least two sets of RSCs (e.g., at least two set of SMTCs), which information is received by at least UE 212. An RSC provides information about one or more RSs. An SMTC provides information about one or more RSs used for measurements. The embodiments are applicable for measurements on any type of RS, such as SSB, CSI-RS, DMRS, etc.

[0056] The UE selects an RSC set (i.e., a single RSC or a group of RSCs) based on one or more criterions and uses the selected RSC(s) for performing one or more operational tasks (e.g., performing one or more measurements on one or more cells etc.) The selection of the RSC(s) may depend on the capabilities of the UE 212 in terms of number of supported RSCs. Examples of criteria are priority level associated with a set of RSCs, received signal level (e.g. path loss, reference signal received power (RSRP), reference signal received quality (RSRQ), etc.) at the UE in the cell. The criteria can be pre-defined or configured by a network node. [0057] In one embodiment, UE 212 compares a received signal level with at least one signal level threshold and selects an RSC set (i.e., a group of RSCs or a single RSC) based on the comparison. In another embodiment, each RSC set is assigned a priority and the UE selects the RSC sets based on the priorities (e.g., UE selects highest priority RSC). The priority information can be communicated to the UE in a variety of ways.

[0058] To illustrate the various embodiments, it will be assumed that UE 212 is configured with at least two sets of RSCs (a first set of one or more RSCs and a second set of one or more RSCs). Accordingly, in one embodiment UE 212 may be configured with a first RSC and a second RSC, while in another embodiment UE 212 may be configure with a first group of one or more RSCs and a second group of one or more RSCs. For example, in one embodiment, network node 206 transmits to UE 212 an RRC message comprising a measurement object (MO) information element (IE) that identifies a first RSC and a second RSC for a certain carrier frequency. The term carrier frequency may also be called as carrier frequency layer, carrier or layer. Information about the carrier frequency is indicated to the UE in the MO by frequency channel number (e.g., ARFNC, NR-ARFCN etc ). One or more cells may belong to or operate on the indicated carrier frequency. Embodiments are applicable for any number of RSCs per MO configured in a cell for enabling the UE to perform the measurements on one or more cells of the carrier frequency. Embodiments are applicable for measurements on any type of RS.

[0059] Each RSC (e.g., SMTC) transmitted to the UE in a MO is associated with corresponding RSC parameters (e.g., in case RSC is an SMTC the SMTC parameters includes: SMTC index or identifier (e.g. SMTC1), SMTC duration, SMTC periodicity and time offset etc.). In general, an RSC may comprises: an RS index or identifier (e.g. RSI), RS duration, RS periodicity, time offset etc.

[0060] In one embodiments, multiple SMTC configurations are enabled by introducing different time offsets. Two or more SMTC configurations are considered as at least partly overlapped in time provided that their SMTC durations at least partly overlap in time. They may also be called as partly or partially overlapping SMTC configurations. Two or more SMTC configurations are considered as fully overlapped in time provided that their SMTC durations fully overlap in time. They may also be called as fully overlapping SMTC configurations. When SMTC durations of two or more SMTC configurations do not overlap in time at all, then they are called as non-overlapping SMTC configurations.

[0061] One example is depicted in FIG. 3, where 4 RSCs per MO or per frequency layer are transmitted/configured in cell 214. As shown in the figure, RSC # 1 (RSC_1) and RSC # 4 (RSC_4) do not overlap in time, RSC # 2 (RSC_2) and RSC # 3 (RSC_3) partly overlap in time due to different time offsets. RSC 1, RSC 2, RSC 3 and RSC 4 indicate indexes or identifiers of multi-RSC; they can also be referred to as RRC IE parameters.

[0062] In one example, measurement adaptation or adaptive measurement or adaptive measurement procedure enables UE 212, while maintaining the connection with network node 206, to measure on signals with different rate and/or periodicity and/or over different time period in certain RRC states (e.g., in RRC IDLE/RRC INACTIVE).

[0063] In a low activity RRC states (e.g. in RRC IDLE/RRC IN ACTIVE state), the UE needs to measure the SSB of neighboring cells to perform cell reselection. In low activity RRC states, the UE typically performs measurement on signals (e.g., SSB) of one or more cells (e.g. satellites) once every K^th DRX cycle (e g. K=l, K=2 etc.). To ensure the UE can detect the SSB of neighboring cell accurately, system information of the current serving cell will include the RSC of neighboring cells per carrier frequency (e g. RSC_1, RSC_2 etc.). In one example, the number of RSCs transmitted (e g. broadcasted) is N which may be less than maximum number of RSCs that can be supported.

[0064] In RRC_CONNECTED state, network node 206 (or another access point) may transmit to UE 212 an RRC message identifying a set of N RSCs. For example, the RRC message may contain an MO IE that contains information identifying each RSC included in the set of N RSCs. An RSC can be based on the propagation delay difference between at least one target cell and the serving cell of a given UE. An RSC can be adaptively updated based on change in the propagation delay difference over time. In one example, the number of RSCs signaled by NW is N which may be less than or equal to the maximum number (M) of RSCs which can be supported by the network.

[0065] When a UE is in the RRC IDLE/RRC INACTIVE state, the network (NW) (e.g., network node 206) can’t provide a UE specific RSC to UE 212 by dedicated signaling (e.g. RRC signaling). In one example, RSCs by NW including RSC indexes or identifiers, RSC periodicity, RSC offset, RSC duration are different in RRC IDLE/RRC INACTIVE state and in RRC CONNCETED state.

[0066] UE 212 may support up to Nmax number of RSCs for performing one or more measurements. In one example, Nmax=4. UE 212 can indicate its capability in terms of maximum number of supported RSCs by transmitting a message via signaling (e.g. in RRC configuration message, in non-access stratum (NAS) signaling message etc ). The capability of supporting certain number (P) (where P < Nmax) of RSC implies that UE 212 can perform one or more measurements using P RSC on one or more cells of a carrier frequency.

[0067] In one example, capability of RSCs supported by UE may be indicated in terms of one or more parameters related to the RSC (e.g. RSC identifier, RSC periodicity, RSC offset, RSC duration etc.). In one example, UE 212 may indicate that it can support certain number of RSCs for any set of RSC parameters. In another example, UE 212 may indicate that it can support certain number of RSCs for specific set of RSC parameters (e.g., UE can support P RSCs provided that at least the RSC periodicity is the same for all RSCs but their RSC durations and/or time offset can be different). In one example UE 212 may indicate that the capability of RSCs supported by UE 212 is different in RRC IDLE/IN ACTIVE state and RRC CONNCETED state. In another example, capability of RSCs supported by UE can be same in

RRC IDLE/INACTIVE state and RRC CONNCETED state.

[0068] Criteria for RSC(s) Selection

[0069] UE 212 selects at least a single RSC or at least a group of RSCs configured by the NW in a MO for certain carrier frequency based on criteria (a.k.a., rule). One or more of the selection criterions can be pre-defined and/or configured by the NW. Examples criterions include: received signal level, location, time and other kinds of metrics at UE 212, and/or the priority levels associated with the configured RSCs.

[0070] RSC Selection Based On Received Signal Level

[0071] In one example, UE 212 selects from a set of RSCs (i.e., RSC 1, RSC 2, ..., RSC_N) at least one an RSC (denoted RSC_i) based on a relation between a received signal level (S) at UE 212 in a cell and a signal level threshold (H). In general, the RSC_i is selected based on relation or function between S and threshold (H).

[0072] A general example of a function for determining RSC i based on relation between S and Hk is expressed by (1) as follows:

RSC_i = f(S, H) (1)

[0073] In another example, UE 212 selects from a set of N RSC groups (i.e., RSCG I, RSCG 2, ..., RSCG N) at least one an RSC group (denoted RSCG i) based on a relation between a received signal level (S) at UE 212 in a cell and a signal level threshold (G).

[0074] In this example, in general RSC group i (RSCG_i) is selected based on relation or function between S and threshold (G). The RSC group (RSCG) may comprises one or more RSCs. Different RSC groups may have the same size or different size. The size of the RSC group may be pre-defined or configured by the network node. In one example, an RSC group may contain only one RSC. In another example, an RSC group may contain two RSCs, etc.

[0075] In one example UE 212 may use all RSCs in the selected group if UE 212 supports at least the number of RSCs in the group. In another example, UE 212 may select a subgroup of the RSCs in the selected group of the RSCs, for performing measurements. In one example, UE 212 may select any subgroup of the RSCs in the selected group. In another example, UE 212 may select the subgroup of RSCs based on one or more RSC parameters. In one specific example, UE 212 may select the subgroup of RSCs which have the largest RSC durations in the selected group. In one example, the subgroup of RSC may comprise one RSC. In another example, the subgroup of RSCs may comprise the number of RSCs supported by UE 212 (e.g., based on UE 212 capability.

[0076] A general example of a function for determining RSCG i based on relation between S and Gk is expressed by (2) as follows:

RSCG i = f(S, G) (2)

[0077] Examples of function f(S,H) and f(S,G) are maximum, minimum, sum, comparison, ceiling, floor, product, average, xth percentile, combination of two or more functions etc. [0078] Examples of received signal level (S) are signal strength, signal quality etc., estimated or measured by UE 212 on signal received by UE 212. Examples of signal strength are path loss, RSRP etc. Examples of signal quality are RSRQ, SNR, SINR etc.

[0079] The thresholds (e.g., G, H) can be pre-defined or configured by the network node (e.g., via signalling such as RRC etc.).

[0080] A general example of determining RSC i based on a comparison between S and H when N number of RSCs are configured is shown in table 3. A specific example of determining RSC i based on a comparison between S and 3 thresholds (Hl, H2 and H3) when 4 RSCs are configured is shown in table 4. Another specific example of determining RSC_i based on a comparison between S and one (Hl) when 2 RSCs are configured is shown in table 5.

TABLE 3: A general example of determining the RSC out of ‘N’ number of configured RSCs based on received signal level

TABLE 4: A specific example of determining the RSC out of 4 RSCs based on received signal level.

TABLE 5: A specific example of determining the RSC out of 2 RSCs based on received signal level.

[0081] A general example of determining RSC group i based on a comparison between S and G when N number of RSC groups (RSCGs) are configured is shown in table 6. A specific example of determining RSCG_i based on a comparison between S and one threshold (Gl) when 2 RSCGs are configured is shown in table 7. In this example each RSCG contains 2 RSCs. Another specific example of determining RSCG_i based on a comparison between S and one threshold (Gl) when also 2 RSCGs are configured is shown in table 8. However, in this example the two groups contain different number of RSCs (e.g., RSCG_1 and RSCG_2 contain 1 RSC and 3 RSCs, respectively.

TABLE 6: A general example of determining the RSC group out of ‘N number of configured RSCGs based on received signal level

TABLE 7: A specific example of determining the RSC group out of 2 RSC groups based on received signal level.

TABLE 8: A specific example of determining the RSC group out of 2 RSC groups based on received signal level.

[0082] RSC Selection Based On Other Metrics

[0083] There are other metrics UE 212 can use to select RSC(s). One example is that UE 212 selects the RSC(s) based on a relation between RSC validity time at UE 212 in a cell and a time length threshold (H_validtime). Another example is that UE 212 selects the RSC(s) based on a relation between RSC burst size at UE 212 in a cell and a time length threshold (H_burst). Another example is that UE 212 the RSC(s) based on a relation between RSC offset at UE 212 in a cell and a time length threshold (H_ offset). Another example is that UE 212 selects the RSC(s) based on a relation between distance between serving cell center/edge and UE in a cell and a distance threshold (H_Ls). Another example is that UE 212 selects the RSC(s) based on a relation between distance between neighbor cells center/edge and UE in a cell and a distance threshold (H_ Ln).

[0084] RSC Selection Based on Priority Levels

[0085] In another example, UE 212 selects the RSC(s) based on the priority level associated with the RSCs and the number of RSCs that UE 212 can support. The priority level associated with the RSCs can be determined based on a rule, which can be pre-defined, or can be configured by the NW. The number of RSCs that UE 212 can support may depend on whether or not the RSCs overlap. For instance, UE 212 can support 4 simultaneous non- overlapping RSCs (see FIG. 4A); but UE 212 cannot support simultaneous overlapping RSCs (see e.g., RSC_2 and RSC 3 shown in FIG. 4B).

[0086] Besides RSCs signaled by NW (e. g. in RRC IDLE/INACTIVE state or RRC_CONNCETED state), NW may also provide priority information associated with the RSCs. UE 212 may choose the highest priority RSC(s) according to the obtained priority information. In one embodiment, the priority information is provided per MO, (i.e., the priority information prioritizes between RSCs in the same MO) and UE 212 will not compare priority levels of RSCs configured in different MOs.

[0087] In one example, the priority information is shown in table 9 as an example, in which priority level is RSC_1> RSC_2> RSC_3> RSC_4 (i.e., RSC_1 has highest priority and RSC_4 has the lowest priority). The priority information can be pre-defined or configured by NW (e.g., RRC configuration).

TABLE 9

[0088] In configuration information, priorities associated with RSCs may be explicitly indicated (e.g., priority levels 1 - N). That is, each configured RSC set may be associated with a priority level number indicating the priority of the RSC(s) in the RSC set. Alternatively, the priorities may be implicitly configured. For instance, the priorities may be implied by the order in which the RSCs appear in the configuration data (e.g., in the MO IE).

[0089] In one example, the order in which the RSCs appear in the configuration data is based on RSC offsets, which may indicate propagation delay, from shortest one to longest one or from longest one to shortest one. [0090] In another example, the order in which the RSCs appear in the configuration data is based on overlap due to RSC offsets, from the RSC(s) with the smallest, or no overlap to the RSC(s) with the largest overlap. Alternatively, the RSCs can be ordered from the RSC(s) with the largest overlap to the RSC(s) with the smallest, or no overlap.

[0091] In another example, the order in which the RSCs appear in the configuration data is based on RSC periodicity, from shortest one to longest one or from longest one to shortest one.

[0092] In another example, the order in which the RSCs appear in the configuration data is based on RSC duration, from shortest one to longest one or from longest one to shortest one. [0093] In another example, the order in which the RSCs appear in the configuration data is based on RSC validity time, from shortest one to longest one or from longest one to shortest one.

[0094] In another example, each RSC is associated with a different satellite and the order in which the RSCs appear in the configuration data is based on the distance from the satellite to a serving satellite. Hence, the RSC associated with the satellite closes to the serving satellite may be listed first and the RSC associated with the satellite furthers from the serving satellite may be listed last.

[0095] In another example, in case of quasi-earth-fixed cells, RSCs are ordered based on the remaining time until the cell(s) they are associated with will disappear (i.e. stop serving their respective geographical area). The ordering could be from longer to shorter remaining service time or from shorter to longer remaining service time.

[0096] Below are some examples of different selection rules.

[0097] If UE 212 is capable of using only a single RSC and is configured by the NW with 4 RSCs, UE 212 shall use the RSC with highest priority as its measurement window, when performing measurements in accordance with the MO configuration.

[0098] If UE 212 is capable of using only two RSCs and is configured by the NW with 4 RSCs, UE 212 shall use the two RSCs with highest priorities (i.e., the RSC having the highest priority and the RSC having the 2nd highest priority) as its measurement window, when performing measurements in accordance with the MO configuration.

[0099] In another example, the priority information is shown in Table 10. Compared with Table 9, table 10 explicitly indicates each RSC priority which is pre-defined or configured by the NW1 (e.g., via RRC configuration).

TABLE 10 Alternative RSC priority information

[00100] According to table 10, if UE 212 is capable of using only one RSC and is configured by the NW with 2 RSCs, UE 212 shall use RSC_1 as its measurement window when performing measurements in accordance with the MO configuration (i.e., select the RSC with highest priority).

[00101] According to table 10, if UE 212 is capable of using only a single RSC and is configured by the NW with RSC_2 and RSC 3, then UE 212 use RSC_2 as its measurement windows when performing measurements in accordance with the MO configuration (i.e., select the RSC with highest priority). [00102] According to table 10, if UE 212 is capable of using only two RSCs and is configured by the NW with 4 RSCs, UE 212 shall use RSC_1 and RSC_2 as its measurement windows when performing measurements in accordance with the MO configuration.

[00103] In another example, priority level can also be different for different UE capabilities. As shown in table 11, a change of priority compared with table 10 is, for UEs capable of using only 2 RSCs, RSC_2 has 3^rd priority and RSC_3 has 2^nd priority. In this sense, If UE 212 is capable of using only two RSCs and is configured by the NW with all four RSCs, UE 212 shall use RSC_1 and RSC_3 as its measurement windows, when performing measurements in accordance with the MO configuration. TABLE 11

[00104] In another example, the priority information is shown in Table 12, in which the priority queue is decided based on Cell/SSB-IDs and/or Satellite IDs/types as example.

[00105] One example is that the priority queue is RSC associated with Cell/SSB-IDs and/or Satellite ID/type A > RSC associated with Cell/SSB-IDs and/or Satellite IDs/types B > RSC associated with Cell/SSB-IDs and/or Satellite IDs/types C > RSC associated with Cell/SSB-IDs and/or Satellite IDs/types D.

[00106] According to table 12, if UE 212 is capable of using only a single RSC then UE 212 shall always use RSC which is associated with Cell/SSB-IDs and/or Satellite ID/type A as its measurement window, when performing measurements in accordance with the MO configuration. TABLE 12

[00107] As another example, the priority information is shown in Table 13. Compared with Table 12, table 13 explicitly indicates each RSC priority which may be pre-defined or configured by NW.

TABLE 13

[00108] Combination of criteria for determining RSCs

[00109] In another example, UE 212 may select one or more RSCs based on combination of criteria (e.g., based on received signal level and network configured priority level).

[00110] In one example, if UE 212 is capable of using only a single RSC (e.g. can only measure 1 RSC in one occasion) and each available RSC has the same priority, then UE 212 selects the RSC based on the received signal level. If, however, one of the available RSCs has a priority higher than the rest, then UE 212 select the RSC having the highest priority.

[00111] The priority group-based solution can bring benefit when the number of defined priorities is greater than 1 but less than the number of RSCs which UE shall support.

[00112] In the example illustrated by the table 14 below, this hybrid solution would mean that a UE capable of using 3 RSCs use RSC_1, RSC_2 and RSC_4 (since they all have priority 1 while RSC_3 has priority 2 and thus cannot replace any of the priority 1 RSCs). A UE capable of using only two RSCs would use RSC_1 and one of RSC_2, RSC_3 and RSC_4, wherein the choice between RSC_2, RSC_3 and RSC_4 is UE autonomous (e.g., based on specified, configured or implementation specific criteria). A UE capable of using only a single RSC would use RSC_4.

TABLE 14

[00113] Using the Selected RSC(s)

[00114] UE 212 may use the selected RSC(s) to perform one or more operational tasks. Examples of tasks include:

[00115] (1) Signaling to the NW information about the RSCs selected; the information may comprise indexes or identifiers of the RSCs selected;

[00116] (2) Signaling to the NW information about (e.g. indexes, identifiers etc) the selected RSCs which are actually used by UE 212 for performing a measurement; and

[00117] (3) Signaling to the NW measurement results (e.g., successful SSB identification or failed SSB identification or measured power level, such as SSB RSRP) on RSCs which are measured with by UE.

[00118] In one embodiment, the NW may change RSCs including number of RSCs based on above indications from UE.

[00119] Validity of UE-based choice solution or NW controlled indication

[00120] RSC utilization by UE 212 shall be treated as a dynamic changeable configuration, wherein the validity may base on: Time (e.g., serving time determined according to remaining serving time of the current cell or/neighboring cell) and/or Location (e g., distance between UE 212 and the satellite or the distance between UE 212 and the cell center or the distance between UE 212 and a cell reference location exceeds a given threshold). [00121] In one embodiment, when a selected RSC becomes invalid (e.g., due to timer expiration), UE 212 informs the NW and the NW can send new/updated MO with new RSCs Alternatively, the NW itself can determine that the selected RSC(s) is invalid and then provide new/updated MO to UE with new set of RSCs. In general, the validity conditions or the conditions for invalidation of RSCs, may be signaled by the network (e.g., combined with, or associated with, the RSCs (and signaled together)).

[00122] Additional embodiments

[00123] The following additional embodiments or options are mainly targeting UEs in RRC IDLE or RRC INACTIVE state, but applicability in RRC CONNECTED state is not excluded, especially if the network is not aware of UE 212’s capability to handle parallel RSCs, (e.g., because UE 212 has not signaled this in its capability signaling).

[00124] In one embodiment, the RSC priorities the network configures are location or area dependent. For instance, different sets of priorities may be associated with (i.e. applicable in) different areas (e.g., defined as different sectors of a cell, or different beam coverage areas, or as geographical areas) The area and shape description means specified in 3GPP TS 23.032 can be used for this purpose. Depending on where UE 212 is located in the cell, it will thus apply different sets of priorities associated with the configured RSCs.

[00125] In another embodiment, the RSC priorities the NW configures are dynamic in the sense that they may change over time in accordance with a configured or specified rule or algorithm (or a configured index pointing out one of a set of specified rules or algorithms). This may result in that the priority order of the configured RSCs change over time.

[00126] In another embodiment, a UE may base the selection further on the distances or propagation delays to the concerned satellites (i.e. the satellites serving the cells with associated RSCs) or the propagation delays to the concerned gNBs (i.e. the gNBs serving the cells for which the RSCs apply). For instance, UE 212 may give higher priority to (and thus preferably select) RSCs for which UE 212-satellite distance or propagation delay, or the gNB-UE propagation delay, is smaller than to RSCs for which UE 212-satellite distance or propagation delay, or the gNB-UE propagation delay, is greater. These priorities, and UE 212’s consequent RSC selection may thus change with the movement of satellites (and also with the movements of UE 212), resulting in changes in UE 212 autonomous prioritization and selection of RSCs. This scheme depends on that UE 212 knows the ephemeris data of the concerned satellite, as well as its own location (which may be obtained through GNSS measurements), and, in the case of the gNB-UE propagation delay (assuming the transparent payload architecture with the gNB on the ground) UE 212 also has to be informed by the network of the gNB-satellite feeder link delay.

[00127] In yet another embodiment, a UE which cannot simultaneously apply all the configured RSCs may apply a time division multiplexing (TDM) scheme, applying a subset (or just one) of the configured RSCs at a time.

[00128] In some embodiments, UE 212’s capability to handle parallel RSCs may be flexible, such as depending on the RSC periodicity (e.g. longer periodicity may imply that a greater number of parallel RSCs can be handled), whether RSCs overlap or not, how much the RSCs overlap, etc.

[00129] In some embodiments, a UE may not be able to handle overlapping RSCs and thus may handle N non-overlapping RSCs but will have to ignore all but one of a group of overlapping RSC windows (i.e. a group of windows whose envelope becomes a single large window). As an example, when this is applied to the RSCs of FIG. 3 (and N > 3), UE 212 could support either RSC_1, RSC_2 and RSC_4 or RSC_1, RSC_3 and RSC_4, since UE 212 (with this embodiment) can handle only one of the overlapping RSC_2 and RSC_3 windows.

[00130] An option, which may be combined with any of the previously described embodiments, is that UE 212’s capability restriction on the number of parallel RSCs it can support can be separate for SSB-MTC, SSB-MTC2 and/or SSB-MTC3. In general, the restriction on the number of parallel RSCs a UE can support may be assumed to apply per measurement object (MO), while there may be no, or a different, restriction on the number of measurement objects UE 212 can handle (which thus means that the number of supported RSCs across all MOs will be greater than the number of RSCs UE 212 can support for each MO).

[00131] Any of the previously described embodiments may be combined.

[00132] FIG. 5 is a flowchart illustrating a process 500, according to an embodiment.

Process 500 may be performed by UE 212 and may begin in step s502. [00133] Step s502 comprises obtaining information identifying N RSC sets (N > 1), where each RSC set comprises one or more RSCs. For example, in one embodiment, the received information identifies N RSCs and in another embodiment the received information identified N groups of RSCs.

[00134] Step s504 comprises selecting M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N.

[00135] Step s506 comprises using at least one of the selected M RSC sets to perform one or more tasks.

[00136] In some embodiments, the first selection criterion is a signal level criterion, a validity time criterion, a priority criterion, a location criterion, or a time criterion.

[00137] In some embodiments, the N RSC sets comprises a first RSC set, RSC_S1, and a second RSC set, RSC_S2, the first selection criterion is the signal level criterion, and selecting the M RSC sets from the N RSC sets comprises: the UE receiving a signal; the UE determining a signal level, S, of the received signal; and the UE comparing S to a first signal level threshold, Hl. In some embodiments, selecting the M RSC sets from the N RSC sets further comprises the UE selecting RSC_S1 as a result of determining that S is less than Hl . In some embodiments, selecting the M RSC sets from the N RSC sets further comprises the UE selecting RSC_S2 as a result of determining that S is greater than Hl .

[00138] In some embodiments, selecting the M RSC sets from the N RSC sets further comprises: the UE comparing S to a second signal level threshold, H2, and the UE selecting RSC_S2 as a result of determining that S is greater than Hl and determining that S is less than H2.

[00139] In some embodiments, the N RSC sets comprises a first RSC set, RSC_S1, and a second RSC set, RSC_S2, the first selection criterion is the validity time criterion, and selecting the M RSC sets from the N RSC sets comprises: the UE determining a first validity time for RSC SI; the UE determining a second validity time for RSC S2; and the UE selecting the M RSC sets using the determined validity times. [00140] In some embodiments, the first selection criterion is the priority criterion, each one of the N RSC sets has a corresponding priority, and the UE selects the M RSC sets based on the corresponding priorities. In some embodiments, the set of selection criterions further comprises a second selection criterion, the second selection criterion is the signal level criterion, and selecting the M RSC sets from the N RSC sets comprises: the UE selecting J RSC sets from the N RSC sets based on the corresponding priorities, wherein M < J < N, the UE receiving a signal; the UE determining a signal level, S, of the received signal; and the UE selecting the M RSC sets from the J RSC sets using S and a signal threshold.

[00141] In some embodiments, obtaining the information identifying the N RSC sets comprises receiving a radio resource control (RRC) message comprising a MO IE, wherein the MO IE comprises the information identifying the N RSC sets.

[00142] In some embodiments, RSC is an SMTC.

[00143] In some embodiments, each RSC set consists of a single RSC.

[00144] In some embodiments, process 500 also includes transmitting to a network node a message comprising information identifying the selected RSCs.

[00145] In some embodiments, using one or more of the selected M RSC sets to perform one or more tasks comprises using at least one of the M RSC sets to measure a reference signal.

[00146] FIG. 6 is a flowchart illustrating a process 600, according to an embodiment. Process 600 may be performed by a network node (e.g., network node 206) and may begin in step s602.

[00147] Step s602 comprises transmitting information identifying N reference signal configuration, RSC, sets, wherein N > 1 and each RSC set comprises one or more reference signal configurations, RSCs.

[00148] Step s604 comprises transmitting information for enabling UE to select M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N.

[00149] In some embodiments, the first selection criterion is: a signal level criterion, a validity time criterion, a priority criterion, a location criterion, or a time criterion. [00150] In some embodiments, the N RSC sets comprises a first RSC set, RSC_S1, and a second RSC set, RSC_S2, the first selection criterion is the validity time criterion, and the method further comprises transmitting information enabling the UE to determine a first validity time for RSC_S1 and determine a second validity time for RSC_S2. [00151] In some embodiments, transmitting the information identifying the N RSC sets comprises transmitting a radio resource control, RRC, message comprising a measurement object (MO) information element (IE) wherein the MO IE comprises the information identifying the N RSC sets. The table below illustrates an example MO IE.

TABLE 15 - Example MO IE

A description of the IES contained with the MO is provided in the tables below:

The IE SSB-MTC is used to configure measurement timing configurations, i.e., timing occasions at which the UE measures SSBs. The table below shows the details of the SSB-MTC IE.

[00152] In some embodiments, the first selection criterion is the priority criterion, and each one of the N RSC sets has a corresponding priority. In some embodiments, the MO IE identifies the corresponding priorities. In some embodiments, the MO IE comprises an ordered list of N RSC set identifiers and the position of an RSC set identifier in the list signals the priority of the RSC set identified by the RSC set identifier.

[00153] In some embodiments, each RSC is an SMTC.

[00154] In some embodiments, each RSC set consists of a single RSC.

[00155] In some embodiments, process 600 further includes receiving a message comprising information identifying selected RSCs.

[00156] FIG. 7 is a block diagram of UE 212, according to some embodiments. As shown in FIG. 7, UE 212 may comprise: processing circuitry (PC) 702, which may include one or more processors (P) 755 (e.g., one or more general purpose microprocessors and/or one or more other processors, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like); communication circuitry 748, which is coupled to an antenna arrangement 749 comprising one or more antennas and which comprises a transmitter (Tx) 745 and a receiver (Rx) 747 for enabling UE 212 to transmit data and receive data (e.g., wirelessly transmit/receive data); and a storage unit (a.k.a., “data storage system”) 708, which may include one or more non-volatile storage devices and/or one or more volatile storage devices. In embodiments where PC 702 includes a programmable processor, a computer readable medium (CRM) QQ342 may be provided. CRM QQ342 stores a computer program (CP) 743 comprising computer readable instructions (CRI) 744. CRM 742 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some embodiments, the CRI 744 of computer program 743 is configured such that when executed by PC 702, the CRI causes UE 212 to perform steps described herein (e g., steps described herein with reference to the flow charts). In other embodiments, UE 212 may be configured to perform steps described herein without the need for code. That is, for example, PC 702 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and/or software.

[00157] FIG. 8 is a block diagram of a network node 206, according to some embodiments, that can implement any one or more of the network nodes described herein. That is, network node 206 can perform the above described network node method. As shown in FIG.

8, network node 206 may comprise: processing circuitry (PC) 802, which may include one or more processors (P) 855 (e.g., a general purpose microprocessor and/or one or more other processors, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like), which processors may be co-located in a single housing or in a single data center or may be geographically distributed (i.e., network node 206 may be a distributed computing apparatus); at least one network interface 848 comprising a transmitter (Tx) 845 and a receiver (Rx) 847 for enabling network node 206 to transmit data to and receive data from other nodes connected to a network 110 (e.g., an Internet Protocol (IP) network) to which network interface 848 is connected (directly or indirectly) (e.g., network interface 848 may be wirelessly connected to the network 110 via an AP and a core network, in which case network interface 848 is connected to an antenna arrangement); and a storage unit (a.k.a., “data storage system”) 808, which may include one or more non-volatile storage devices and/or one or more volatile storage devices. In embodiments where PC 802 includes a programmable processor, a computer readable medium (CRM) 842 may be provided. CRM 842 stores a computer program (CP) 843 comprising computer readable instructions (CRI) 844. CRM 842 may be a non-transitory CRM, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some embodiments, the CRI 844 of computer program 843 is configured such that when executed by PC 802, the CRI causes network node 206 to perform steps described herein (e.g., steps described herein with reference to the flow charts). In other embodiments, network node 206 may be configured to perform steps described herein without the need for code. That is, for example, PC 802 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and/or software.

[00158] Summary of Various Embodiments

[00159] Al. A method performed by a user equipment, UE, the method comprising: obtaining information identifying N reference signal configuration, RSC, sets, wherein N > 1 and each RSC set comprises one or more reference signal configurations, RSCs; selecting M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N; and using at least one of the selected M RSC sets to perform one or more tasks.

[00160] A2. The method of embodiment Al, wherein the first selection criterion is: a signal level criterion, a validity time criterion, a priority criterion, a location criterion, or a time criterion.

[00161] A3. The method of embodiment A2, wherein the N RSC sets comprises a first

RSC set, RSC_S1, and a second RSC set, RSC_S2, the first selection criterion is the signal level criterion, and selecting the M RSC sets from the N RSC sets comprises: the UE receiving a signal; the UE determining a signal level, S, of the received signal; and the UE comparing S to a first signal level threshold, Hl .

[00162] A4. The method of embodiment A3, wherein selecting the M RSC sets from the N

RSC sets further comprises the UE selecting RSC_S1 as a result of determining that S is less than Hl.

[00163] A5. The method of embodiment A3, wherein selecting the M RSC sets from the N

RSC sets further comprises the UE selecting RSC_S2 as a result of determining that S is greater than Hl.

[00164] A6. The method of embodiment A3, wherein selecting the M RSC sets from the N

RSC sets further comprises: the UE comparing S to a second signal level threshold, H2, and the UE selecting RSC_S2 as a result of determining that S is greater than Hl and determining that S is less than H2. [00165] A7. The method of embodiment A2, wherein the N RSC sets comprises a first

RSC set, RSC_S1, and a second RSC set, RSC_S2, the first selection criterion is the validity time criterion, and selecting the M RSC sets from the N RSC sets comprises: the UE determining a first validity time for RSC_S1; the UE determining a second validity time for RSC_S2; and the UE selecting the M RSC sets using the determined validity times.

[00166] A8. The method of embodiment A2, wherein the first selection criterion is the priority criterion, each one of the N RSC sets has a corresponding priority, and the UE selects the M RSC sets based on the corresponding priorities.

[00167] A9. The method of embodiment A8, wherein the set of selection criterions further comprises a second selection criterion, the second selection criterion is the signal level criterion, and selecting the M RSC sets from the N RSC sets comprises: the UE selecting J RSC sets from the N RSC sets based on the corresponding priorities, wherein M < J < N, the UE receiving a signal; the UE determining a signal level, S, of the received signal; and the UE selecting the M RSC sets from the J RSC sets using S and a signal threshold.

[00168] Al 0. The method of any one of embodiments Al -A9, wherein obtaining the information identifying the N RSC sets comprises receiving a radio resource control, RRC, message comprising a measurement object, MO, information element, IE, wherein the MO IE comprises the information identifying the N RSC sets

[00169] Al l. The method of any one of embodiments A1-A10, wherein each RSC is an SSB measurement time configuration, SMTC.

[00170] Al 2. The method of any one of embodiments Al -Al l, wherein each RSC set consists of a single RSC.

[00171] Al 3. The method of any one of embodiments Al -Al 2, further comprising: transmitting to a network node a message comprising information identifying the selected RSCs.

[00172] A14. The method of any one of embodiments Al-13, wherein using the selected

M RSC sets to perform one or more tasks comprises: using at least one of the M RSC sets to measure a reference signal. [00173] 17. A method performed by a network node, the method comprising: transmitting information identifying N reference signal configuration, RSC, sets, wherein N > 1 and each RSC set comprises one or more reference signal configurations, RSCs; and transmitting information for enabling a user equipment, UE, to select M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N.

[00174] B2. The method of embodiment 17, wherein the first selection criterion is: a signal level criterion, a validity time criterion, a priority criterion, a location criterion, or a time criterion.

[00175] B3. The method of embodiment B2, wherein the N RSC sets comprises a first

RSC set, RSC_S1, and a second RSC set, RSC_S2, the first selection criterion is the validity time criterion, and the method further comprises transmitting information enabling the UE to determine a first validity time for RSC_S 1 and determine a second validity time for RSC_S2.

[00176] B4. The method of embodiment B2, wherein transmitting the information identifying the N RSC sets comprises transmitting a radio resource control, RRC, message comprising a measurement object, MO, information element, IE, wherein the MO IE comprises the information identifying the N RSC sets.

[00177] B5. The method of embodiment B4, wherein the first selection criterion is the priority criterion, and each one of the N RSC sets has a corresponding priority.

[00178] B6. The method of embodiment B5, wherein the MO IE identifies the corresponding priorities.

[00179] B7. The method of embodiment B6, wherein the MO IE comprises an ordered list of N RSC set identifiers and the position of an RSC set identifier in the list signals the priority of the RSC set identified by the RSC set identifier.

[00180] B8. The method of any one of embodiments 17-B7, wherein each RSC is an SSB measurement time configuration, SMTC.

[00181] B9. The method of any one of embodiments 17-B8, wherein each RSC set consists of a single RSC. [00182] 170. The method of any one of embodiments 17-B9, further comprising: receiving a message comprising information identifying selected RSCs.

[00183] Cl. A computer program (743) comprising instructions (744) which when executed by processing circuitry (702) of a UE (212) causes the UE to perform the method of any one of embodiments Al -Al 4.

[00184] C2. A computer program (843) comprising instructions (844) which when executed by processing circuitry (802) of a network node (206) causes the network node to perform the method of any one of embodiments 17-170.

[00185] C3. A carrier containing the computer program of embodiment Cl or C2, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium (842).

[00186] DI. A user equipment, UE (212), the UE (212) being configured to: obtain information identifying N reference signal configuration, RSC, sets, wherein N > 1 and each RSC set comprises one or more reference signal configurations, RSCs; select M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N; and use at least one of the selected M RSC sets to perform one or more tasks

[00187] D2. A user equipment, UE (212), the UE (212) comprising processing circuitry

(702) and a memory (742), the memory containing instructions (744) executable by the processing circuitry whereby the UE is configured to: obtain information identifying N reference signal configuration, RSC, sets, wherein N > 1 and each RSC set comprises one or more reference signal configurations, RSCs; select M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N; and use at least one of the selected M RSC sets to perform one or more tasks.

[00188] D3. The network node of embodiments DI or D2, wherein the network node is further configured to perform the method of any one of embodiments A2-A14.

[00189] El. A network node (206), the network node (206) being configured to: transmit information identifying N reference signal configuration, RSC, sets, wherein N > 1 and each RSC set comprises one or more reference signal configurations, RSCs; and transmit information for enabling a user equipment, UE, to select M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N.

[00190] E2. A network node (206), the network node (206) comprising processing circuitry (802) and a memory (842), the memory containing instructions (844) executable by the processing circuitry whereby the network node is configured to: transmit information identifying N reference signal configuration, RSC, sets, wherein N > 1 and each RSC set comprises one or more reference signal configurations, RSCs; and transmit information for enabling a user equipment, UE, to select M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N.

[00191] E3. The network node of embodiments El or E2, wherein the network node is further configured to perform the method of any one of embodiments B2-170.

[00192] While various embodiments are described herein, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of this disclosure should not be limited by any of the above-described exemplary embodiments. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

[00193] Additionally, while the processes described above and illustrated in the drawings are shown as a sequence of steps, this was done solely for the sake of illustration. Accordingly, it is contemplated that some steps may be added, some steps may be omitted, the order of the steps may be re-arranged, and some steps may be performed in parallel.

Claims

44 CLAIMS

1. A method (500) performed by a user equipment, UE, (212) the method comprising: obtaining (s502) information identifying N reference signal configuration, RSC, sets, wherein N > 1 and each RSC set comprises one or more reference signal configurations, RSCs; selecting (s504) M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N; and using (s506) at least one of the selected M RSC sets to perform one or more tasks.

2. The method of claim 1, wherein the first selection criterion is: a signal level criterion, a validity time criterion, a priority criterion, a location criterion, or a time criterion.

3. The method of claim 2, wherein the N RSC sets comprises a first RSC set, RSC_S1, and a second RSC set, RSC_S2, the first selection criterion is the signal level criterion, and selecting the M RSC sets from the N RSC sets comprises: the UE receiving a signal; the UE determining a signal level, S, of the received signal; and the UE comparing S to a first signal level threshold, Hl .

4. The method of claim 3, wherein selecting the M RSC sets from the N RSC sets further comprises the UE selecting RSC_S1 as a result of determining that S is less than Hl.

5. The method of claim 3, wherein selecting the M RSC sets from the N RSC sets further comprises the UE selecting RSC_S2 as a result of determining that S is greater than Hl. 45

6. The method of claim 3, wherein selecting the M RSC sets from the N RSC sets further comprises: the UE comparing S to a second signal level threshold, H2, and the UE selecting RSC_S2 as a result of determining that S is greater than Hl and determining that S is less than H2.

7. The method of claim 2, wherein the N RSC sets comprises a first RSC set, RSC_S1, and a second RSC set, RSC_S2, the first selection criterion is the validity time criterion, and selecting the M RSC sets from the N RSC sets comprises: the UE determining a first validity time for RSC_S 1 ; the UE determining a second validity time for RSC_S2; and the UE selecting the M RSC sets using the determined validity times.

8. The method of claim 2, wherein the first selection criterion is the priority criterion, each one of the N RSC sets has a corresponding priority, and the UE selects the M RSC sets based on the corresponding priorities.

9. The method of claim 8, wherein the set of selection criterions further comprises a second selection criterion, the second selection criterion is the signal level criterion, and selecting the M RSC sets from the N RSC sets comprises: the UE selecting J RSC sets from the N RSC sets based on the corresponding priorities, wherein M < J < N, the UE receiving a signal; the UE determining a signal level, S, of the received signal; and the UE selecting the M RSC sets from the J RSC sets using S and a signal threshold. 46

10. The method of any one of claims 1-9, wherein obtaining the information identifying the N RSC sets comprises receiving a radio resource control, RRC, message comprising a measurement object, MO, information element, IE, wherein the MO IE comprises the information identifying the N RSC sets.

11. The method of any one of claims 1-10, wherein each RSC is an SSB measurement time configuration, SMTC.

12. The method of any one of claims 1-11, wherein each RSC set consists of a single RSC.

13. The method of any one of claims 1-12, further comprising: transmitting to a network node a message comprising information identifying the selected RSCs.

14. The method of any one of claims 1-13, wherein using the selected M RSC sets to perform one or more tasks comprises: using at least one of the M RSC sets to measure a reference signal.

15. The method of any one of claims 1-14, wherein the at least one of the selected M RSC sets comprises a first RSC and a second RSC, and using the at least one of the selected M RSC sets to perform one or more tasks comprises: applying the first RSC at a first time, and applying the second RSC at a second time subsequent to the first time.

16. The method of any one of claims 1-14, wherein the M RSC sets comprise a first RSC set and a second RSC set, the first RSC set comprises a first RSC, the second RSC set comprises a second RSC, and using the at least one of the selected M RSC sets to perform one or more tasks comprises: applying the first RSC at a first time, and applying the second RSC at a second time subsequent to the first time.

17. A method (600) performed by a network node (206), the method comprising: transmitting (s602) information identifying N reference signal configuration, RSC, sets, wherein N > 1 and each RSC set comprises one or more reference signal configurations, RSCs; and transmitting (s604) information for enabling a user equipment, UE, to select M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N.

18. The method of claim 17, wherein the first selection criterion is: a signal level criterion, a validity time criterion, a priority criterion, a location criterion, or a time criterion.

19. The method of claim 18, wherein the N RSC sets comprises a first RSC set, RSC_S1, and a second RSC set, RSC_S2, the first selection criterion is the validity time criterion, and the method further comprises transmitting information enabling the UE to determine a first validity time for RSC_S1 and determine a second validity time for RSC_S2.

20. The method of claim 18, wherein transmitting the information identifying the N RSC sets comprises transmitting a radio resource control, RRC, message comprising a measurement object, MO, information element, IE, wherein the MO IE comprises the information identifying the N RSC sets.

21. The method of claim 20, wherein the first selection criterion is the priority criterion, and each one of the N RSC sets has a corresponding priority.

22. The method of claim 21, wherein the MO IE identifies the corresponding priorities.

23. The method of claim 22, wherein the MO IE comprises an ordered list of N RSC set identifiers and the position of an RSC set identifier in the list signals the priority of the RSC set identified by the RSC set identifier.

24. The method of any one of claims 17-23, wherein each RSC is an SSB measurement time configuration, SMTC.

25. The method of any one of claims 17-24, wherein each RSC set consists of a single RSC.

26. The method of any one of claims 17-25, further comprising: receiving a message comprising information identifying selected RSCs.

27. A computer program (743) comprising instructions (744) which when executed by processing circuitry (702) of a UE (212) causes the UE to perform the method of any one of claims 1-16.

28. A computer program (843) comprising instructions (844) which when executed by processing circuitry (802) of a network node (206) causes the network node to perform the method of any one of claims 17-26.

29. A carrier containing the computer program of claim 27 or 28, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium (742, 842). 49

30. A user equipment, UE (212), the UE (212) being configured to: obtain information identifying N reference signal configuration, RSC, sets, wherein N > 1 and each RSC set comprises one or more reference signal configurations, RSCs; select M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N; and use at least one of the selected M RSC sets to perform one or more tasks.

31. A user equipment, UE (212), the UE (212) comprising processing circuitry (702) and a memory (742), the memory containing instructions (744) executable by the processing circuitry whereby the UE is configured to: obtain information identifying N reference signal configuration, RSC, sets, wherein N > 1 and each RSC set comprises one or more reference signal configurations, RSCs; select M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N; and use at least one of the selected M RSC sets to perform one or more tasks.

32. The UE of claim DI or D2, wherein the UE is further configured to perform the method of any one of claims 2-16.

33. A network node (206), the network node (206) being configured to: transmit information identifying N reference signal configuration, RSC, sets, wherein N > 1 and each RSC set comprises one or more reference signal configurations, RSCs; and transmit information for enabling a user equipment, UE, to select M RSC sets from the N RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N.

34. A network node (206), the network node (206) comprising processing circuitry (802) and a memory (842), the memory containing instructions (844) executable by the processing circuitry whereby the network node is configured to: 50 transmit information identifying N reference signal configuration, RSC, sets, wherein N >

1 and each RSC set comprises one or more reference signal configurations, RSCs; and transmit information for enabling a user equipment, UE, to select M RSC sets from the N

RSC sets based on a set of selection criterions, wherein the set of selection criterions comprises a first selection criterion and M < N.

35. The network node of claims 33 or 34, wherein the network node is further configured to perform the method of any one of claims 18-26.