Use of non-terrestrial network for multicast and broadcast services

Abstract

A base station provides a multicast / broadcast service (MBS) in a wireless communication system. The base station transmits, to a non-terrestrial network (NTN) cell, information on one or more MBS ses

Description

BACKGROUND Field

[0001] Certain examples of the present disclosure provide approaches for using nonterrestrial networks for multicast and broadcast services. Description of Related Art

[0002] The content of the following documents is referred to below and / or their content provides background information and context that the following disclosure should be considered in view of: 3GPP TS 38.331 v18.0.0 January 2024 3GPP TS 36.331 V18.0.0 January 2024 3GPP TS 36.306 V18.0.0 January 2024 3GPP TS 38.304 V18.00 January 2024 3GPP TS 38.300 V18.0.0. January 2024 3GPP TS 38.213 V18.1.0 January 2024 3GPP TS 38.323 V18.0.0 January 2024 3GPP TS 38.322 V18.0.0 January 2024 3GPP TS 36.213 V18.1.0 January 2024 3GPP TS 36.304 V18.1.0 January 2024 3GPP TS 23.247 V18.4.0 December 2023 RP-211557 3GPP TSG RAN meeting #91-e e-meeting, March 22 - 26th, 2021 RP-202689 3GPP TSG RAN Meeting #90 Electronic Meeting, December 7 - 11,2020 RP-220953 3GPP TSG RAN Meeting #95e Electronic Meeting, March 17-23, 2022 RP-220979 3GPP TSG RAN Meeting #95e Electronic Meeting, March 17-23, 2022 RP-234078 3GPP TSG RAN Meeting #102, December 11-15, 2023 R2-2313780 3GPP TSG RAN WG2 Meeting #124, November 13-17, 2023 (Note: the example versions shown for each TS are non-limiting, other versions of the TS may be considered also)

[0003] Wireless or mobile (cellular) communications networks in which a mobile terminal (e.g., user equipment (UE), such as a mobile handset) communicates via a radio link with a network of base stations, or other wireless access points or nodes, have undergone rapid development through a number of generations. The 3rd Generation Partnership Project (3GPP) design, specify and standardise technologies for mobile wireless communication networks. Fourth Generation (4G) and Fifth Generation (5G) systems are now widely deployed, and development of Sixth Generation (6G) Systems is in progress.

[0004] 3GPP standards for 4G systems include an Evolved Packet Core (EPC) and an Enhanced-UTRAN (E-UTRAN: an Enhanced Universal Terrestrial Radio Access Network). The E-UTRAN uses Long Term Evolution (LTE) radio technology. LTE is commonly used to refer to the whole system including both the EPC and the E-UTRAN, and LTE is used in this sense in the remainder of this document. LTE should also be taken to include LTE enhancements such as LTE Advanced and LTE Pro, which offer enhanced data rates compared to LTE.

[0005] In 5G systems a new air interface has been developed, which may be referred to as 5G New Radio (5G NR) or simply NR. NR is designed to support the wide variety of services and use case scenarios envisaged for 5G networks, though builds upon established LTE technologies. New frameworks and architectures are also being developed as part of 5G networks in order to increase the range of functionality and use cases available through 5G networks.

[0006] In recent years, Non-Terrestrial Network (NTN) and Air-To-Ground (ATG) networks have been considered and their operation integrated into 3GPP systems in order to enhance coverage and / or provide alternative coverage mechanisms. Non-Terrestrial Networks (NTNs)

[0007] NR NTN (NR_NTN_solutions-Core) [RP-211557] was a 3GPP Work Item in 3GPP Release 17 to define solutions to enable New Radio (NR) and NG-RAN to support NTN. It addressed solutions fortransparent payload for both Geostationary and non-Geostationary network scenarios, with the UE having Global Navigation Satellite System (GNSS) capability and the satellite beams being both earth-fixed or earth-moving.

[0008] Figure 1 provides an illustration of an example NTN where a gateway (GW) 106 provides a feeder link 108 to a satellite 110 and the satellite provides an NTN cell 114 and an access link 116 to a device, such as a UE, within the NTN cell. The gateway may be connected to a gNB / eNB 104 which in turn is connected to a core network 102. The gateway 106 may be part of the gNB / eNB 104, separate to or partially integrated. Some of the functions of the gNB / eNB may also be implemented in the satellite 110 in some examples.

[0009] Internet of Things (loT) NTN was a 3GPP study and work item in 3GPP release 17 to provide NTN access for E-UTRAN loT devices (NB-loT and LTE-M / eMTC) [RP-202689], NR NTN was a work item in Rel-17 to specify adaptation to allow NR to function over NTN [RP-211557], NTN access may be through Lower Earth Orbit (LEO), Medium Earth Orbit (MEO) and Geostationary Orbit (GEO), as well as through High-Altitude Platform Systems (HAPS).

[0010] Following the work items in Release 17 there were work items to enhance NR NTN [RP-220953] and loT NTN [RP-220979] in Release 18.

[0011] NR NTN phase 3 [RP-234078] is a 3GPP Work Item in 3GPP Release 19 aiming to enhance NR NTN with a range of enhancements: - Downlink coverage enhancements - Uplink capacity and throughput enhancements by using Orthogonal Coverage Codes - MBS broadcast over NTN - Introduction of regenerative payload - Redcap and NTN enhancements - Terrestrial E-UTRAN to NR NTN mobility NTN System Information

[0012] As NTN has a number of NTN-specific information elements that are only required when accessing an NTN cell, and also due to the rather large information elements it was agreed that new system information blocks (SIB) were needed.

[0013] In NR NTN SIB19 contains the required information to access an NTN cell: SIB19 SIB 19 contains satellite assistance information for NTN access. SIB19 information element ref ereneeLoeatiC’n-rl" di a t enee T hra ah-r1" ntn-Neighi-'ellCc'nfigLiet*rl" X<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 1 at eNc’ nCr i t i e al Ext ansi an ma'’ingFefereneeL'2< atian-rlo iiiiiiiiiii MTn-neighdell'Zt'nfigLiat-rl" : : = HeighTellCanfig-rl? LJTIMIeighCellC'anfig-rl" : : = earrierFreq-r17 phyrC'ell Id-rl" ^lllllllllllllll IxtlwitehMthReSyne-rlE : : = n t n - C a n f i a - r 18 t-Ser^i’reStart-rll seb-TiineOffset-rlE Referen^eLacati 2‘n-rl"7 HTIHIeighlellC: nfigliet^rll IITN-neighCellCtrifigLiet-rlF : RaferaneeLaeatian-rl-'7 let E' dtehMthRelynr-rld liilllllllllllllllll^^ LKiEhRR (1- .54175511^17) 1 ;_____________________________________________SIB19 field descriptions_____________________________________________; ; distanceThresh ; Distance from the serving cell reference location and is used in location-based measurement initiation in ; RRC_IDLE and RRC_INACTIVE, as defined in TS 38.304

[20] , Each step represents 50m. This field is only ; present in an NTN cell.___________________________________________________________________________________________________; ; movingReferenceLocaiion ; Reference location of the serving cell of an NTN Earth moving system at a time reference. It is used in location- ; based measurement initiation in RRC_IDLE and RRC_INACTIVE, as defined in TS 38.304

[20] , The time ; reference of this field is indicated by epochTime in ntn-Config of the serving cell. This field is excluded when ; determining changes in system information, i.e., changes to movingReferenceLocaiion should neither result in i system information change notifications nor in a modification of valueTag in SIB1. This field is only present in an i NTN cell. i i ntn-Config i Provides parameters needed for the UE to access NR via NTN access such as Ephemeris data, common TA i parameters, k_offset, validity duration for UL sync information and epoch. In a TN cell, this field is only present in ; [ ntn-NeighCellConfigList and ntn-NeighCellConfigListExt. i i nin-NeighCeliConfigUsi, ntn-NeighCeiiConfigListExi i Provides a list of NTN neighbour cells including their ntn-Config, carrier frequency and PhysCellld. This set i includes all elements of ntn-NeighCellConfigList and all elements of ntn-NeighCellConfigListExt. If ntn-Config is i absent for an entry in ntn-NeighCellConfigListExt, the ntn-Config provided in the entry at the same position in ntn- i i NeighCellConfigList applies. Network provides ntn-Config for the first entry of ntn-NeighCellConfigList. If the ntn-i Config is absent for any other entry in ntn-NeighCellConfigList, the ntn-Config provided in the previous entry in i ntn-NeighCellConfigList applies. i i referenceLocaion 1 i Reference location of the serving cell provided via NTN quasi-Earth fixed system and is used in location-based i measurement initiation in RRC_IDLE and RRC_INACTIVE, as defined in TS 38.304

[20] , This field is only ; present in an NTN cell.___________________________________________________________________________________________________i i satSwitchWithReSync i Provides parameters for the target satellite required to perform satellite switch with re-synchronization. This field i is only present in an NTN cell and its presence indicates that satellite switch without PCI change is supported in i the cell. i i t-Service i Indicates the time information on when a cell provided via NTN system is going to stop serving the area it is ; currently covering. This field applies for both service link switches in NTN quasi-Earth fixed system and feeder ; link switches for both NTN quasi-Earth fixed and Earth moving system. The field indicates a time in multiples of ; 10 ms after 00:00:00 on Gregorian calendar date 1 January, 1900 (midnight between Sunday, December 31, ; 1899 and Monday, January 1, 1900). The exact stop time is between the time indicated by the value of this field ; minus 1 and the time indicated by the value of this field. The reference point for t-Service is the uplink time ; synchronization reference point of the cell. This field is only present in an NTN cell.__________________________________; In loT NTN SIB31 contains the required information to access an loT NTN cell: - SystemlnformationBlockType31 The IE SystemlnformationBlockTypeil contains satellite assistance information for the serving cell. SystemlnformationBlockTypeil is only signalled for an NTN cell. SysteminformationBlockType31 information element ::= SRvUEMCE { C'rbit^lF'&raifiet^rs Eph^ifierisOrbit alFareim^ter^-rl" bBbBbBbBbBbO nt a-Ochaim-Kl IlITEaER H ' - . Ai ■- - OFTIOHa.L, .... <y Ad d d < iOAi bbOOcObbOO^ BBBBBBBBiBiBtl^OO^BB^^ — Na ad ^FF si -Sync aliOityEnnaticn-rlO EIILH-IEFATED (s5, clu, nlS, =Ey OFT 101 JAL i a_£, c>', si — Haai FT, a4u. Itii s45, a5uf a55, and, alLO, al80 , SE40, s90S I apochTima-rlT BbBOAbO?^^^^ at art EubFrama-r1" Illllltlo^OI il 1 Bis lOOiOAL^I — Naad OALaOFATAB B B B B B B B B B B B B B B B B B B - BaAArAABiBBB — 1'Jaad :B:B:AAO0Os0AO8B:B:B:B lllllllllll iBiBdABAOdB OF i BBOBaAWoOAO I: OO£| : | : : : : : : : :^^ bbbbbbb F.af arenaaLncatian-rlc , HK'VinqCall-rlc' lllllllllllllll^^ B:B:B:B:B:B:B:B:B:B:B:B:B:OiOdOd£Od:tOrid^ iBOTiOOBBi — Naad iiOi IB di at annaThra ah-rl £ OFT 101 JAL i — Haai OF i AE1I1ET0F _________________________SystemlnformationBlockType31 field descriptions_________________________: distanceThresh Distance from the serving cell reference location and is used in location-based measurement initiation in : RRC_IDLE (as specified in TS 36.304 [4]) and RRC_CONNECTED. Each step represents 50m._____________: epochTime Epoch time of the satellite ephemeris data and common TA parameters, see TS 36.213

[23] , This field also i indicates the epoch time for the reference location of earth moving cells if present. The reference point for i epoch time of the serving satellite ephemeris and Common TA parameters is the uplink time synchronization i reference point when this field is provided in an NTN cell and the eNB when this field is provided in a TN cell, : epochTime is the starting time of a DL subframe indicated by startSFN and startSubframe. For serving cell, : the startSFN indicates the current SFN or the next upcoming SFN after the frame where the message : indicating the epochTime is received. : If the field is absent, the UE uses the starting time of the DL subframe corresponding to the end of the SI : window during which the SI message carrying SIB31(-NB) is transmitted. i E-UTRAN always includes epochTime when SIB31(-NB) is provided through dedicated signalling. i In case of handover or conditional handover, this field is based on the timing of the target cell, i.e. the i startSFN and startSubFrame number indicated in this field refers to the SFN and sub-frame of the target cell, i and UE considers the target cell epoch time (indicated by the startSFN and startSubFrame in this field) to be i the frame nearest to the frame where RRCConnectionReconfiguration message is received. i k-Mac Scheduling offset used when downlink and uplink frame timing are not aligned at the eNB, see TS 36.213 i

[23] , Unit in ms. i If the field if absent, the UE uses the (default) value of 0. i k-Offset Scheduling offset used in the timing relationships in NTN, see TS 36.213

[23] , Unit in ms. i nta-Common Network-controlled common TA, see TS 36.213

[23] , Unit of ps. i Step of 32.55208 xl 0-3 ps. Actual value = field value * 32.55208 xl 0-3. i If the field is absent, the UE uses the (default) value of 0. i nia-CommonDrift Drift rate of the common TA, see TS 36.213

[23] , Unit of ps / s. i Step of 0.2 xW3ps / s. Actual value = field value * 0.2 x10-3. i If the field is absent, the UE uses the (default) value of 0.__________________________________________________________I nta-CommonDriftVariation Drift rate variation of the common TA, see TS 36.213

[23] , Unit of ps / s2. i Step of 0.2 xW4ps / s2. Actual value = field value * 0.2 xio-4. i If the field is absent, the UE uses the (default) value of 0.__________________________________________________________I orbiialParameiers Instantaneous values of the satellite orbital parameters. The signalled values are valid at least for the duration i as defined by ul-SyncValidityDuration and epochTime._____________________________________________________I referenceLocation Reference location of the NTN quasi-earth fixed cell or earth moving cell, used in location-based i measurement initiation in RRC_IDLE (as specified in TS 36.304 [4]) and RRC_CONNECTED. If configured i by an earth moving cell, the broadcast reference location corresponds to the epoch time, and the UE derives i the real-time reference location based on the serving satellite ephemeris, see TS 36.304 [4].___________________: stateVectors Instantaneous values of the satellite state vectors. The signalled values are valid at least for the duration as i defined by ul-SyncValidityDuration and epochTime.________________________________________________________: ul-SyncValidityDuration Validity duration of the satellite ephemeris data and common TA parameters, i.e. maximum time duration i (from epochTime) during which the UE can apply the satellite ephemeris without acquiring new satellite : ephemeris, see TS 36.213

[23] , Unit in second. : Value s5 corresponds to 5 seconds, value slO corresponds to 10 seconds and so on. : The ul-SyncValidityDuration is only updated when at least one of epochTime, nta-CommonParameters, : ephemerisinfo is updated.______________________________________________________________________________________:

[0014] The system information contains, among other things, the following: - Serving cell Ephemeris elements - which allows UE to calculate the satellite position for doppler and time pre-compensation. This can be of two formats: o PVT format - which describes a (X,Y,Z) position as well as a speed vector (vX, vY, vZ) o Orbital parameters - this describes the orbital movements of the satellite which is then used to infer the satellite position - TA common parameters - this provides the common timing advance parameters which is introduced to compensate for the feeder link delays. The signaling consists of (in total taking up 57 bits) o Absolute TA common, taking up 23 bits o Drift of the TA common - how the TA common drifts, i.e. the first derivative, taking up 19 bits o Variation of the TA common - how the TA common varies, i.e. the second derivative of the TA common, taking up 15 bits - Synchronization validity duration - used to define how long the ephemeris and TA common is valid Epoch time - when the synchronization validity duration should start K-Offset - scheduling offset for timing relationship in NTN K-Mac - Scheduling offset used when the downlink and uplink frame timing is not aligned NR NTN specific information also include (as part of 38.331): o T-Service (signaled in SIB3 in loT NTN) o Reference location and distance threshold - used for location-based measurement initiation in RRC IDLE and RRC Connected mode o Neighbour cell ephemeris ■ This is used for idle mode measurements NTN System Information Acquisition

[0015] As the ephemeris constantly changes due to the movement of the NTN payload, there is a need to make sure that the UE is correctly synchronized. Thus whenever a UE is connected to an eNB, the UE needs to read the system information. There is furthermore a timer (T317) associated with the ephemeris element that is started every time SIB31 is read. At expiry of T317, the UE is no longer considered synchronized and it will have to re-acquire SIB31 in order to stay synchronized. In NR NTN, the UE shall ensure that it has a recent ephemeris (SIB19 in NR) by reading the SIB in time by UE implementation. In loT NTN, since an loT UE (LTE-M and NB-loT UE) is not expected to be able to acquire system information in connected mode, the UE tunes away and is likely unreachable while reading SIB31. If the loT NTN UE is unable to read the SIB31 within a timer (T318) with a configured duration, the UE performs RLF similar to other cases where Radio Link Failure (RLF) is performed. This operation (ephemeris synchronization) can be seen in Figure 2, where in a) SIB31 functions as normal (i.e. within the T318 timer that has been triggered by the expiry of the T317 timer) and b) where UE fails to read SIB31 during T318 which then expires and triggers RLF.

[0016] The T317 timer is different compared to a normal timer in RRC as it is not started at having received the SIB31. This is because the ephemeris has an epoch time, which is the reference point in time of when the ephemeris is defined. Thus the T317 is started from the epoch time, which may be in the past or in the future relative to have received SIB31. This means that in a UE implementation, the timer may be started with a different value with what was signaled according to what was signaled in the field ul-SyncValidityDuration in SIB31. Idle and Inactive Mode Mobility

[0017] Idle and inactive mode mobility is based on a UE autonomously performing measurements and deciding according to some rules whether a UE shall re-select to another cell or not to camp on.

[0018] During cell selection, the UE identifies suitable cells, which is according to a cell suitability criteria based on signal strength and signal quality measurements. After identifying one or several suitable cells, the UE can choose any of them.

[0019] During cell re-selection, the UE searches intra-frequency cells, inter-frequencies cells and inter-RAT cells. Each frequency will have a specific cell reselection priority, and the UE shall always choose a cell of highest priority, given that it is not barred or not allowed to camp on. If cells of equal priority are detected, then the UE shall rank all of the cells, where there ranking metric is based on signal strength and signal quality measurements and then choose the best candidate. The UE then camps on the newly re-selected cell. 5G MBS Broadcasting

[0020] Multicast / Broadcast Service (MBS) is a feature introduced in 3GPP Release 17 for 5G NR. It follows similar features introduced in previous generations of cellular communication standards, a notable case being Multimedia broadcast / Multicast Services (MBMS) introduced in 4G LTE.

[0021] As the name suggest, MBS feature can provide either multicast communication services, or broadcast communication services. For broadcast communication services, the same service and the same content data are provided simultaneously to all UEs in an area. For multicast communication services, the same service and content are provided to a configured set of UEs. Broadcast communication services can be received in RRC_IDLE, RRC_INACTIVE and RRC_CONNECTED, while multicast can only be received in RRC_CONNECTED.

[0022] MBS can also be provided to Redcap (reduced capability) UEs.

[0023] In order to receive the broadcast communication services when a UE is interested in receiving a broadcast service, the UE does the following: 1. A UE identifies that a cell is providing broadcast communication services. This is identified by a gNB broadcasting the system information SIB20. This can be acquired in RRCJDLE, RRC_INACTIVE and RRC_CONNECTED. a. The SIB20 contains the following information: i. mcch-Config contains the configuration of the MBS Control Channel (MCCH) ii. cfr-ConfigMCCH-MTCH contains the common frequency resource (CFR) which is used for MCCH and MBS Traffic Channel (MTCH) reception. This configuration in turn contains the frequency location and bandwidth, the PDSCH Config for MCCH and potentially a common control resource set. 2. The mcch-Config is then used to configure the UE to receive MCCH, where the RRC message MBSBroadcastConfiguration is sent. The MBSBroadcastConfiguration contain the following configuration: a. MTCH info in PDSCH Config and MTCH-SSB mapping i. MTCH PDSCH config contains the configuration to receive the broadcast data traffic b. MBS session info list i. Provides list of MBS sessions that are provided in the current cell. The session info contains 1. MBS session ID 2. The G-RNTI used for scrambling of MTCH 3. MBS Radio Bearer (MRB) configuration, i.e PDCP-Config and RLC-Config 4. MTCH neighbour cell, which are the neighbouring cells that the session is provided in. 5. PDSCH Config of the MTCH 6. MTCH to SSB mapping index c. MBS neighbour cell list which is a list of cells and the carrier frequencies d. DRX configuration - which can be used to perform DRX in RRC_CONNECTED 3. If a session that a UE is interested in following is present, the UE establishes an MRB using one of the configurations and then proceeds to receive the broadcast session on the indicated MTCH channel according to the configurations and continues to monitor MCCH.

[0024] The network can also broadcast other System Information used for service continuity of an MBS broadcast by broadcasting the SIB21. SIB21 provides the UE with information regarding the mapping between the serving and neighbouring carrier frequencies and the MBS Frequency Selection Area Identities (MBS FSAI). This is divided up in to information regarding the FSAIs on the intra frequency as well as FSAI on inter-frequencies.

[0025] Once the UE has acquired the SIB21, the UE can send a so-called MBSInterestlndication. MBSInterestlndication is an RRC message that is sent in RRC_CONNECTED to indicate to the network that it is interested in receiving a MBS broadcast service. The sending of this message can be triggered due to a range of reasons. The MBSInterestlndication can contain the frequencies that the UE wants to receive on, whether MBS shall have higher priority than user data, the MBS services the UE wants to receive. Example content of SIB20 and SIB21 is set out below. SIB20: SIB20 SIB20 contains the information required to acquire the MCCH / MTCH configuration for MBS broadcast. SIB20 information element mcch-Confip-rl7 1 ICCH-Config-rl", in-EWingf^ 'iTF-CintWKd'H-mCH-rl" < morh-CcTifiQFedCap-rlH 1 ICCH-Confip-rlO < mcch-RepetiticnE^riodAndOffet-rl? HCCH-RepetiticnFe-riv-iRndOf f ^et-rlF f in -'ll-T7in3~ DuidtKh-ir {_1_, 114, -lb p clip _ 141 ।, - 1 ', m h-ll 1111 -tti nF-n 1-11" . ... {it-, 114, ii>, 1-11« , it it> 4, itLp II >H-F-^lili nF = n< l-ii iOtt-^l-i 1 ::= ' u {■ ■ U , iipitllililililililii ECU U. ........................................................................ UES\(C>. . E , ilBpSE .31) , EUJEU. iiiiiiiiiiiiiiiiiiiii UUP (u. .355) SIB20 field descriptions cfr-ConfigMCCH-MTCH Common frequency resource used for MCCH and MTCH reception. If the field is absent, the CFR for broadcast has the same location and size as CORESET#0 and PDSCH configuration of MCCH is the same as PDSCH configuration provided in initialDownlinkBWP in SIB1. cfr-ConfigMCCH-MTCH-RedCap Common frequency resource used for MCCH and MTCH reception for RedCap UEs. If the field is absent, the RedCap UE can use cfr-ConfigMCCH-MTCH if the UE supports the configured bandwidth. mcch-WindowDuraiion Indicates, starting from the slot indicated by mcch-WindowStartSlot, the duration in slots during which MCCH may be scheduled. Absence of this field means that MCCH is only scheduled in the slot indicated by mcch-WindowStartSlot. The network always configures mcch-WindowDuration to be shorter or equal to the length of MCCH repetition period. mcch-ModificaiionPeriod Defines periodically appearing boundaries, i.e. radio frames for which SFN mod mcch-ModificationPeriod = 0. The contents of different transmissions of MCCH information can only be different if there is at least one such boundary in-between them. Value rf2 corresponds to two radio frames, value rf4 corresponds to four radio frames and so on. mcch-RepetiiionPeriodAnddffset Defines the length and the offset of the MCCH repetition period. rf1 corresponds to a repetition period length of one radio frame, rf2 corresponds to a repetition period length of two radio frames and so on. The corresponding integer value indicates the offset of the repetition period in the number of radio frames. MCCH is scheduled in the MCCH transmission window starting from each radio frame for which: SFN mod repetition period length = offset of the repetition period. mcch-WindowStarisiot Indicates the slot in which MCCH transmission window starts. SIB21: SIB21 SIB21 contains the mapping between the current and / or neighbouring carrier frequencies and MBS Frequency Selection Area Identities (FSAI). SIB21 information element mba-FSAI-IntcaFr^q-cl? I IEF-FCAI-Li3t-Kl~ / / / / / / / liiilili.OOO:iilii3SlilW / ili / / / / / / / / / / / / / / / / / / / / / / liit3S^ 1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111115^ I IEe-F^ -1-11" ::= - - <. । _________________________________________SIB21 field descriptions_______________________________________ mbs-FSAI-inierFreqUsi Contains a list of neighboring frequencies including additional bands, if any, that provide MBS services and the corresponding MBS FSAIs.__________________________________________________________________________ mbs-FSAI-lntraFreq Contains the list of MBS FSAIs for the current frequency. For MBS service continuity, the UE shall use all MBS FSAIs listed in mbs-FSAI-lntraFreq to derive the MBS frequencies of interest. MBS Idle / lnactive Mode Procedures

[0026] In order for a UE to receive a broadcast service, the UE needs to camp on a cell that provides the service. Since the UE may receive broadcast services in RRCJDLE and RRC_INACTIVE, there needs to be some way of handling of how the UE performs idle and inactive mode procedures, to ensure that there is service continuity even when the UE is not in RRC_CONNECTED. Without this, the UE may perform cell reselection and re-select to a cell that does not provide any of the broadcasted services.

[0027] The idle and inactive mode cell reselection procedures are based on measuring intra-frequency cells, inter-frequency cells and inter-RAT cells. Each of these frequencies and cells may have a priority called a cell reselection priority, which is a number from 0 to 7 that defines how prioritized a frequency is in the cell reselection algorithm. A UE shall for instance not reselect to a cell on frequency with lower priority as long as there are suitable cells that are on a high priority cells. For intra-frequency or inter-frequency cells of the same priority, the UE applies ranking of the cells in order to determine which cell to camp on. This ranking (cell ranking criterion R) is based on signal strength measurements along with configured offsets.

[0028] The idle and inactive mode cell reselection procedures are enhanced to ensure service continuity by doing the following: If there is only a single frequency in which the UE can receive the MBS broadcast service, the UE may consider this frequency to be highest priority, under two conditions that must be fulfilled: o This makes it so that the UE does not reselect to another cell that may have higher priority but does broadcast the MBS broadcast service o The first condition that must be fulfilled is that the cell of the selected frequency must broadcast SIB20 (SIB containing MCCH configuration) o Either one of the following: ■ MBS FSAI is indicated in SIB21 of the cell and the same MBS FSAI matches with the broadcast in the MBS User Service Description (USD) ■ SIB21 is not provided in the serving cell, but the frequency is included in the USD ■ SIB21 is provided in the serving cell, but... - The UE may consider other frequencies where it cannot receive the MBS broadcast service to be of the lowest priority o This makes it so that the UE only reselects among cells that perform the MBS broadcast service Relevant Terms

[0029] As defined in TS 23.247 V18.4.0 - Architectural enhancements for 5G multicastbroadcast services: • MBS service area: The area within which data of one Multicast or Broadcast MBS session may be sent. For location dependent MBS, for each MBS service area, an Area Session ID, which is unique per MBS Session ID, is allocated and the same location dependent content data for an MBS session is delivered to the UE(s) within an MBS service area. • Broadcast service area: The area within which data of one or multiple Broadcast MBS session(s) are sent.

[0030] In RP-234078, there is the following objective in the work item description: 3. Specify signaling of the intended service area of a broadcast service (e.g. MBS broadcast) via NR NTN [RAN2, RAN3] • Specify SIB signaling to indicate the intended service area in case the satellite footprint covers a larger area. [RAN2] • Specify the necessary signaling between CN and NG-RAN. [RAN3]

[0031] The justification for this objective is: 1) MBS feature provides an important add-value for NR NTN system, leveraging the large coverage of the NTN compared to TN. Terrestrial MBS features are equally available for NR NTN in the 5G specifications, but for some cases the intended service area is expected to be smaller than the coverage of a Uu cell, and some enhancements need to be done to notify the service area of a Broadcast service.

[0032] The reason for this objective is that intended service area for an MBS broadcast service can be smaller than that of an NTN cell. This is because an NTN cell can have a diameter larger than 100 km, whereas the service area may be intended to be much smaller. Using existing methods, it would not be possible for a network to make the service area smaller than the cell, as the cell would broadcast the transmissions associated with the broadcasted area across the cell. This can be seen in Figure 3, wherein the NTN cell area provided by satellite 302 is larger than the area where the (MBS) service is to be provided. To this end, there is a need to make the MBS service area smaller than the cell through signaling, i.e. to create a virtual (i.e. second, reduced, alternative smaller etc.) service area. SUMMARY

[0033] It is an aim of certain examples of the present disclosure to address, solve and / or mitigate, at least partly, at least one of the problems and / or disadvantages associated with the related art, for example at least one of the problems and / or disadvantages described herein. It is an aim of certain examples of the present disclosure to provide at least one advantage over the related art, for example at least one of the advantages described herein.

[0034] In accordance with a first aspect of the present disclosure, there is provided a method of a user equipment (UE) for receiving a multicast / broadcast service (MBS) in a wireless communication system, the method comprising: receiving, at the UE from a non-terrestrial network (NTN) node of the wireless communication system, information on one or more MBS sessions, wherein a respective service area is associated with each of the one or more MBS sessions; and if the UE is within a service area associated with a MBS session of interest from among the one or more MBS sessions, receiving, at the UE from the NTN node, the MBS session of interest.

[0035] In an example, the information on the one or more MBS sessions and / or the respective service areas are received via one or more of a system information block (SIB) and a MBS control channel (MCCH).

[0036] In an example, configuration information of the MCCH is included in one or more system information blocks (SIBs) received from the NTN node.

[0037] In an example, the method further comprises receiving, via the MCCH, configuration information of a MBS traffic channel (MTCH) for the MBS session of interest, wherein the MBS session of interest is received via the MTCH.

[0038] In an example, the method further comprises, if the UE is not within a service area associated with a MBS session of interest, not monitoring the MCCH.

[0039] In an example, the method further comprises, if the UE is within a service area associated with a MBS session of interest, monitoring the MCCH.

[0040] In an example, the method further comprises receiving information on the respective service areas via the MCCH.

[0041] In an example, the respective service areas are geographical areas.

[0042] In an example, each geographical area is defined by a geometric shape.

[0043] In an example, each geographical area is defined by a reference location and a radius.

[0044] In an example, the service area associated with the MBS session of interest is different to a coverage area of a cell provided by the NTN node.

[0045] In an example, the NTN node is a satellite.

[0046] In an example, the information on one or more MBS sessions and the MBS session of interest are received from a base station (e.g. next generation nodeB (gNB)) via the NTN node.

[0047] In an example, the wireless communication system is a 3GPP 5G wireless communication system.

[0048] In accordance with a second aspect of the present disclosure, there is provided a user equipment (UE) configured to perform the method of any of the foregoing aspects and examples

[0049] In accordance with a third aspect of the present disclosure, there is provided a of a base station for providing a multicast / broadcast service (MBS) in a wireless communication system, the method comprising: transmitting, to an non-terrestrial network (NTN) cell, information on one or more MBS sessions and respective service areas associated with each of the one or more MBS sessions; and transmitting, to the NTN cell, the one or more MBS sessions.

[0050] In an example, the information on the one or more MBS sessions and / or the respective service areas are transmitted via one or more of a system information block (SIB) and a MBS control channel (MCCH).

[0051] In an example, configuration information of the MCCH is transmitted in one or more system information blocks (SIBs).

[0052] In an example, the method further comprises transmitting, via the MCCH, configuration information of a MBS traffic channel (MTCH) for the MBS session of interest, wherein the MBS session of interest is received via the MTCH.

[0053] In an example, the method further comprises transmitting information on the respective service areas via the MCCH.

[0054] In an example, the respective service areas are geographical areas.

[0055] In an example, each geographical area is defined by a geometric shape.

[0056] In an example, each geographical area is defined by a reference location and a radius.

[0057] In an example, the service areas are different to a coverage area of the NTN cell.

[0058] In accordance with a fourth aspect of the present disclosure, there is provided a bases station configured to perform the method of any of the aforementioned aspects and examples.

[0059] Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Embodiments / examples of the present disclosure are further described hereinafter with reference to the accompanying drawings, in which: Figure 1 provides a diagram of an example non-terrestrial network (NTN); Figure 2 provides a diagram illustrating timers related to the acquisition of system information for NTNs; Figure 3 provides a diagram illustrating an example scenario where the area of an NTN cell is larger than an area where an MBS service is to be provided; Figure 4 provides a diagram illustrating a UE having access to an MBS service within a reduced area of an NTN cell; Figure 5 provides a diagram illustrating multiple different MCCH / MTCH configurations for a set of geographical areas within an NTN cell; Figure 6 provides a flow diagram illustrating a cell (re)selection and MBS session acquisition procedure in the context of MCCH configurations; Figure 7 provides a diagram illustrating multiple different MBS sessions for a set of geographical areas within an NTN cell; Figure 8 provides a flow diagram illustrating a cell (re)selection and MBS session acquisition procedure in the context of MBS configurations; Figure 9 provides a diagram illustrating multiple different MBS session areas within different MCCH-Config areas; Figure 10 provides a diagram of example MBS session service areas at a first point in time when the cell is provided by a non-stationary satellite; Figure 11 provides a diagram of example MBS session service areas at a second point in time when the cell is provided by a non-stationary satellite; Figure 12 provides a diagram of an example communication flow where a PDU session establishment message includes information on MBS geographical service areas; Figure 13 provides a diagram of an example communications flow where a UE includes a location indication in an MBS interest indication; Figure 14 provide a diagram of an example communication flow where geographical MBS service areas and based on NTN MBS Service and virtual NTN TAIs and CelllDs; and Figure 15 provides a block diagram of an exemplary network entity / function that may be used in certain examples of the present disclosure. DETAILED DESCRIPTION

[0061] The following description of examples of the present disclosure, with reference to the accompanying drawings, is provided to assist in a comprehensive understanding of certain examples of the present disclosure. The description includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the examples described herein can be made without departing from the scope of the invention or disclosure.

[0062] The same or similar components may be designated by the same or similar reference numerals, although they may be illustrated in different drawings.

[0063] Detailed descriptions of techniques, structures, constructions, functions or processes known in the art may be omitted for clarity and conciseness, and to avoid obscuring the subject matter of the present disclosure.

[0064] The terms and words used herein are not limited to the bibliographical or standard meanings, but are merely used to enable a clear and consistent understanding of the disclosure.

[0065] Throughout the description of this specification, the words “comprise”, “include” and “contain” and variations of the words, for example “comprising” and “comprises”, means “including but not limited to”, and is not intended to (and does not) exclude other features, elements, components, integers, steps, processes, operations, functions, characteristics, properties and / or groups thereof.

[0066] Throughout the description of this specification, the singular form, for example “a”, “an” and “the”, encompasses the plural unless the context otherwise requires. For example, reference to “an object” includes reference to one or more of such objects.

[0067] Throughout the description, the expression “at least one of A, B and / or C” (or the like) and the expression “one or more of A, B and / or C” (or the like) should be seen to separately include all possible combinations, for example: A, B, C, A and B, A and C, A and B and C.

[0068] Throughout the description of this specification, language in the general form of “X for Y” (where Y is some action, process, operation, function, activity or step and X is some means for carrying out that action, process, operation, function, activity or step) encompasses means X adapted, configured or arranged specifically, but not necessarily exclusively, to do Y.

[0069] Features, elements, components, integers, steps, processes, operations, functions, characteristics, properties and / or groups thereof described or disclosed in conjunction with a particular aspect, embodiment or example are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

[0070] The following examples are applicable to, and use terminology associated with, 3GPP 4G (e.g., LTE) and / or 5G (e.g., NR). However, the skilled person will appreciate that the techniques disclosed herein are not limited to these examples or to 3GPP 4G (e.g., LTE) and / or 5G (e.g., NR), and may be applied in any suitable system or standard, for example one or more existing and / or future generation wireless communication systems or standards (e.g., B5G, 5G-Advanced, 6G etc.). The skilled person will appreciate that the 19echniquees disclosed herein may be applied in any existing or future releases of 3GPP 4G (e.g., LTE) and / or 5G (e.g., NR) and / or 5G Advanced and / or 6G, and / or (3GPP Release 17, 18, 19, 20, etc.) or any other relevant standard. For example, the functionality of the various network entities and other features disclosed herein may be applied to corresponding or equivalent entities or features in other communication systems or standards. Corresponding or equivalent entities or features may be regarded as entities or features that perform the same or similar role, function, operation or purpose within the network.

[0071] Furthermore, the following also applies to the present disclosure: • The terms functionality / use-case / configuration / scenario / site may be used interchangeably. • The terms model and model functionality may be used interchangeably. • This disclosure also apply to non-3GPP entities. • The concepts, proposals, solutions, methods, embodiments, figures, and / or examples, presented in this disclosure, would apply to various type of communication systems, such as 4G, 4G-Advanced, 5G, 5G-Advanced, and 6G.

[0072] A particular network entity may be implemented as a network element on dedicated hardware, as a software instance running on a dedicated hardware, and / or as a virtualised function instantiated on an appropriate platform, e.g. on a cloud infrastructure.

[0073] The skilled person will appreciate that the present disclosure is not limited to the specific examples disclosed herein. For example: • The techniques disclosed herein are not limited to 3GPP 4G or 5G or 5G-Advanced and also apply to B5G and 6G systems. • One or more entities in the examples disclosed herein may be replaced with one or more alternative entities performing equivalent or corresponding functions, processes or operations. • One or more of the messages in the examples disclosed herein may be replaced with one or more alternative messages, signals or other type of information carriers that communicate equivalent or corresponding information. • One or more further elements, entities and / or messages may be added to the examples disclosed herein. • One or more non-essential elements, entities and / or messages may be omitted in certain examples. • The functions, processes or operations of a particular entity in one example may be divided between two or more separate entities in an alternative example. • The functions, processes or operations of two or more separate entities in one example may be performed by a single entity in an alternative example. • Information carried by a particular message in one example may be carried by two or more separate messages in an alternative example. • Information carried by two or more separate messages in one example may be carried by a single message in an alternative example. • The order in which operations are performed may be modified, if possible, in alternative examples. • The transmission of information between network entities is not limited to the specific form, type and / or order of messages described in relation to the examples disclosed herein. 5G MBS Over NTN

[0074] The present disclosure provides approaches for adapting 5G Multicast Broadcast Services (MBS) to also function over NTN.

[0075] Throughout this disclosure, it should be noted that ephemeris is not only applicable for satellite payloads, but can also apply to other platforms such a HAPS (High Altitude Platform Systems) or to other types of networks such as Air-To-Ground networks. Thus any mention of “satellite ephemeris” may not only apply to satellites but also other NTN platforms and / or payloads.

[0076] Throughout this disclosure, where the term “terrestrial network” is used, this may not only be a terrestrial network, but may also be considered to be any type of network that is not an NTN network. This for instance may include Air-To-Ground networks or similar. Another suitable name may for instance be “non-NTN” and thus a TN cell may thus be a “non-NTN cell”.

[0077] Throughout this disclosure, the wording “RRC connected”, “connected mode” or “RRC_CONNECTED” may be used interchangably. Similarly, “idle mode”, “RRC idle” or ”RRC_IDLE” may be interchangeably used. When methods related to “idle mode” is mentioned, unless otherwise stated, this may also encompass “inactive mode”, “RRC inactive” or “RRC_INACTIVE” as the actions performed in those two states in general are the same.

[0078] Throughout this disclosure, monitoring is generally meant to mean the idle / inactive mode action of detecting and measuring a cell on a frequency, while measuring means the action of detecting and measuring in connected mode. However, the terms may also be used interchangeably.

[0079] The present disclosure is predominantly described in terms of 5G NR, but all proposals, embodiments, and examples may also apply for eNBs or NG-eNBs (eNBs connected via 5GC). And all related, newly defined and / or existing: RRC signaling and / or messages, X2, Xn, S1, NG, and / or F1 signaling and messages, and / or related network entities (e.g. MME, AMF, other). Similarly, while the approaches in this disclosure reference 5G NR MBS, some or all of the approaches may also be relevant to 4G LTE MBMS.

[0080] Throughout this disclosure, the UE may determine by itself whether it is inside or outside an area. The UE can do this by using GNSS or any other positioning techniques to determine its location and use the signaled area (e.g. MBS service area) to determine whether it is inside or outside.

[0081] While the approaches of the present disclosure are described in terms of MBS Broadcast, they may also apply for MBS Multicast. In this case, the MBSBroadcastConfiguration may for instance be replaced by the MBSMulticastConfiguration message, and similar applies to other such broadcast / multicast messages. Restricting Access of an MBS Service to an Area

[0082] MBS services may have (e.g. required or desired) access restrictions based on location and such restrictions should operate in NTN cells. Thus even though the physical beam is broadcasting a specific service in (i.e. across) a non-terrestrial cell, it should be configured that a UE(s) does not have access to the specific service in locations outside of a particular area. This can be seen in Figure 4, which illustrates a reduced service area within an NTN cell area.

[0083] As can be seen from Figure 4 the UE only has access to a service (#1) in a specific location or specific area within the area of the NTN cell, such that in areas within the NTN cell area but outside of the service area the UE does not have access the service #1. To distinguish between the Service Area that can already be defined by means of cells and tracking areas (NR Cell Global Identifier and Tracking Area Identities), in this disclosure an area defined (e.g. using geographical coordinates) for the purpose of restricting access to MBS services may be referred to as a geographical (MBS) service area or MBS service area. However, any other suitable term may be used such as reduced (MBS) service area, permitted (MBS) service area, MBS service zone, MBS service sector, MBS service region, etc, or any suitable combination of any of these terms Furthermore, when the term “service area” is used alone, this should be interpreted as geographical (MBS) service area as opposed to an entire (NTN) cell area or a tracking area, which will be explicitly referred to as such.

[0084] To implement the geographical (MBS) service area(s), a geographical (MBS) service area may be indicated by the 5GC (e.g. received from AF or OAM) to gNB, e.g. during the MBS session join, establishment or modification procedures. One or more (MBS) service area(s) might be indicated during the MBS session join, establishment or modification procedures. The one or more geographical (MBS) service area(s) might be within one cell. The geographical (MBS) service area might be stored by the UDM, per broadcast service and / or per UE. Within one cell there may be multiple geographical (MBS) service area(s) each of which relates to one or more different services and or UEs.

[0085] The gNB may indicate the one or more geographical (MBS) service area(s) to the UE, e.g. via SI, MCCH, etc. Alternatively, the geographical (MBS) service area information might be provisioned to the UE, e.g. from the AF or service provider via application layer information, which is transparent to 3GPP system. Or the information is provided within higher layer information, e.g. MBS User Service Description (USD), as a part of MBS User Service Announcement.

[0086] The geographical service area information might be indicated to the UE before the service starts or after the UE indicate its MBS interests to the network.

[0087] The area (geographical (MBS) service area) used in this disclosure may be a range of different geometrical shapes: The area can be a circle which is defined by a reference location and a radius. Area can be a square defined by a refence location and a diameter. Area can be an hexagon or octagon defined by a reference location and its diameter. The area can be defined by a set of points (3 or more points) that make up an area (i.e. any suitable area may be defined).

[0088] The “area” may be an area on the surface of the earth, or the area may be calculated based on the Euclidean distance. This means that any distance to some points are defined by the distance on the surface of the area.

[0089] The geographical service area may also have a height or altitude component that determines whether a UE on a specific height may receive the service.

[0090] There may also be multiple geographical (MBS) service areas indicated. This can be useful if for instance the geographical area that the service intends to service is irregular. A good example of this is services intended for a specific country. The geographical (MBS) service areas may be overlapping. The UE would thus evaluate whether it is inside of any of the geographical areas indicated for the specific service.

[0091] The geographical (MBS) service areas may either move with the cell, or the geographical (MBS) service areas may be static. The geographical (MBS) service areas might be static even though the geographical (MBS) service areas are covered / served by different NTN / TN cells at different times or at a same time. Alternatively, the geographical (MBS) service areas might be static per (NTN) cell; when coverage is provided by other satellites / gNB, the geographical (MBS) service area(s) might be (re-)configured on a per cell basis / per cell level configuration.

[0092] Furthermore, although geographical restrictions (based on coordinates for example) are predominantly considered, alternative or additional approaches for defining an MBS service area may be used, such discriminating between parts of an NTN cell based on a signal strength or proximity to a specified entity (network or non-network related) for example.

[0093] While the wording used in this disclosure is that access is “restricted in the areas outside of the signalled areas”, it may also be considered that the access is “(only) allowed in the areas inside of the signalled areas”, or alternatively that “MBS NTN access is allowed in the areas inside the signalled areas”. Furthermore, the geographic restrictions on reception of the MBS services may be mandatory (i.e. it is not possible / permitted for UEs outside of the geographical (MBS) service area to receive the MBS service) or optional (i.e. whilst not advertised it is still possible for UEs outside of the geographical (MBS) service area to receive the MBS service).

[0094] Various approaches in accordance with the present disclosure for implementing geographical (MBS) service areas are set out below. Although the various approaches are predominantly described individually, the various approaches may be combined, and / or individual features of one approach may be introduced into another approach. Restricting Access via Location-specific MCCH Configuration

[0095] In an example of the present disclosure, the access restriction to an MBS broadcasting service is done via SIB20.

[0096] In this case the MCCH / MTCH configuration is configured with a specific location(s) / area(s). This can for instance be useful to allow for different MCCH / MTCH configurations for different areas within the cell, which is beneficial if the cell is very large, for instance covering multiple countries.

[0097] It may be such that one country applies a single MCCH / MTCH configuration to allow for commonality.

[0098] The above can be done by introducing multiple MCCH / MTCH configurations that are associated with different specific areas. For instance, MCCH and MTCH configuration 1 is associated location / area 1 and MCCH and MTCH configuration 2 is associated with location / area 2. An example of this can be seen in Figure 5, which illustrates multiple MCCH / MTCH configurations for a set of geographical areas. In particular, within the NTN cell, it can be seen that three different MCCH-config areas are defined: MCCH-Config Area 1, MCCH-Config Area 2, and MCCH Config-Area 3. Although shown as being adjacent and having a square shape, the areas associated with each MCCH / MTCH configuration may take any suitable shape and take any suitable arrangement relative to one another.

[0099] If the UE is outside of any of the service areas (i.e. MCCH / MTCH configuration areas) defined by the locations, then the UE may not / is not permitted to monitor (or continue to monitor) any of the MCCH (configurations) and consider that there is no MBS broadcast service provided in the cell. If a UE is within one of the service areas, it may monitor the MCCH (configurations). In some examples, a UE may only monitor MCCH configurations associated with the area in which it is located.

[00100] In one example, the UE may reselect to another cell if it determines that there are no MCCH configurations for its specific location and / or nearby locations. Thus the condition to reselect to another cell may for instance be that there are no MCCH configurations configured for the UE location, or that the UE is not in an area covered by an MCCH configuration, or similar. The procedure for re-selecting another cell can be seen in an example in Figure 6, where this figure sets out conditions for determining whether to consider a cell for cell selection or cell reselection. Similarly, the cell may not be considered for cell reselection or cell selection when evaluating the cell during cell selection or cell reselection procedure.

[00101] If the UE detects that there is no MCCH configuration in the area of the UE location in a cell (or in any other entities, such as in a Tracking Area or PLMN), the UE may consider that there is no MBS broadcast service at all in the area, for instance for the PLMN, the tracking area or for a specific frequency. This may be useful to ensure that a UE does not re-select or attempt to re-select to another cell when it is important that the UE continues to camp on the cell. The UE may for instance consider that the service is not provided by the cell if the UE location does not correspond to any of the MCCH areas.

[00102] In the example of Figure 6 the procedure (may also be considered to be conditions) is set out below. It should be noted that the procedure of Figure 6 is not limited to only the illustrated steps and that the procedure may include only some of the steps of Figure 6, may include other steps not included in Figure 6, one or more steps may be combined, and / or one or more steps may be separated into separate steps.

[00103] 0a. UE may have already selected the cell or is evaluating whether to re-select or select the cell via cell re-selection or cell selection.

[00104] 0b. UE may have already acquired the UE location (e.g. via GNNS).

[00105] 1. UE acquires the SIB20 of the cell

[00106] 2. UE checks whether it is inside of any of the areas defined by the MCCH configuration included in SIB20. The UE may need to acquire the UE location just before this step if the UE location has not been acquired in advance and / or if the location of the UE is rapidly changing.

[00107] 3a. If the UE is inside one of the areas, the UE monitors MCCH for an MBSBroadcastConfiguration and then further checks whether the MBS Broadcast service that the UE is interested in receiving is available. This means that the condition in TS 38.304 “If the MBS broadcast capable UE is receiving or interested to receive an MBS broadcast service(s) and can only receive this MBS broadcast service(s) by camping on a frequency on which it is provided" is evaluated to true for the specific cell or frequency.

[00108] 4a. If the MBS broadcast service (of interest) is available, the UE acquires the MBS broadcast session.

[00109] 4b. If the MBS broadcast service (of interest) is not available, the UE may not consider the cell for cell selection or cell reselection, similar to 3b.

[00110] 3b. If the UE is not inside any of the areas , the UE considers that there is no MBS broadcast service provided in the cell and may re-select to another cell if the cell has already been selected, and if the cell has not yet been selected, the UE does not consider the cell in cell selection or cell re-selection. This means that the UE does not even consider acquiring MBSBroadcastConfiguration message on any of the configured MCCH. This means that the condition in TS 38.304 “If the MBS broadcast capable UE is receiving or interested to receive an MBS broadcast service(s) and can only receive this MBS broadcast service(s) by camping on a frequency on which it is provided" is evaluated to false for the specific cell or frequency.

[00111] The above steps 0-2 may also be one single step or single condition.

[00112] Having separate MCCH means that there will be multiple MBSBroadcastConfiguration messages, one for each MCCH, and thus at least one for each geographical area. The UE is only required to acquire the MBSBroadcastConfiguration that is relevant to its own UE location. However, in some example, it may also acquire configurations of the neighbouring areas.

[00113] One example on how this can be configured is seen in Example #1a (see end of disclosure) and how it can be specified in the idle and inactive mode procedures can be seen in Example #1b.

[00114] In another example, the UE may consider that any signaled MCCH information for a specific area is common for all cells, for instance within a tracking area, or in a PLMN. Restricting Access via Geographical Service Areas

[00115] Another method of ensuring that the MBS broadcast is only received in a specific area is by limiting the service to a specific area, i.e. a geographical (MBS) service area. In the previous section, this is achieved by having separate MCCH configurations, but in this section this is done by defining areas related to each service. This may for instance mean that there is a single MCCH configuration that the UE monitors.

[00116] This alternative approach can be done by introducing what is known as geographical (MBS) service areas related to MBS Sessions or MBS services. This means that a specific geographical area will be related to an MBS session, which is defined by an MBS session Id. This means that a specific geographical area will have or be configured its own g-RNTI, MRBs, MTCH configuration, PDSCH configuration etc. This can be seen in Figure 7, wherein geographical areas of MBS sessions are illustrated. Additionally, multiple areas may have or be configured with the same g-RNTI, MRBs, MTCH configuration, PDSCH configuration etc. the g-RNTI, MRBs, MTCH configuration, PDSCH configuration might be per MBS session / service level information.

[00117] As can be seen in Figure 7, three different MBS-session service areas are defined: a service area for MBS-Session 1, a service area for MBS-Session 2, and a service area for MBS-Session 3. Although shown as being adjacent and having a square shape, the areas associated with each MBS session may take any suitable shape and take any suitable arrangement relative to one another.

[00118] The geographical service area may in some cases be or extend outside of the coverage area of the cell, which may indicate that another cell also provides the same service in the same area. This can be used by the UE in the cell reselection procedure. This also means that the geographical service areas can be considered global and is thus saved once the UE is no longer connected to the cell. The geographical service areas might be updated or overwritten by the network (5GC, gNB) or the service server. Similar may also apply to the MCCH-Config areas of Figure 5.

[00119] This approach means that when a UE is interested in receiving a service, the UE may further need to check, following acquisition of MCCH configuration information, whether the MBS service that it is interested in is provided where the UE is located. If the UE finds that the service is not provided for the area / UE location, the UE considers that the service is not provided in the cell or the area.

[00120] If the UE detects that there is no related MBS session or service that the UE is interested in in the geographical service area of the UE in a cell, the UE may consider that there is no MBS broadcast service at all in the area, for instance for the PLMN, the tracking area or for a specific frequency. This means that for the PLMN or for the tracking area or for a specific frequency, the MBS session is not provided in the area if it is not indicated in MBSBroadcastConfiguration. Therefore, the UE does not or is not allowed to monitor the DL data of the MBS session or the service. This may be also useful to ensure that a UE does not re-select to another cell to attempt to receive an MBS service that is not provided in the specific location either. The UE may for instance consider that the service is not provided by the cell if the UE location does not correspond to any of the areas of the MBS sessions that the UE is interested in.

[00121] In Figure 8 the procedure (may also be considered to be conditions) for the UE to select a cell is shown. It should be noted that the procedure of Figure 8 is not limited to only the illustrated steps and that the procedure may include only some of the steps of Figure 8, may include other steps not included in Figure 8, one or more steps may be combined, and / or one or more steps may be separated into separate steps.

[00122] 0a. UE may have already selected the cell or is evaluating whether to re-select or select the cell via cell re-selection or cell selection.

[00123] Ob. UE may have already acquired the UE location.

[00124] 1. UE acquires the SIB20 of the cell and configures to receive and monitor MCCH

[00125] 2. UE acquires MBSBroadcastConfiguration

[00126] 3. UE checks whether it is inside of any of the areas defined by the areas as defined by the MBS session for the MBS session(s) that the UE is interested in. The UE may need to acquire the UE location just before this step if the UE location has not been acquired in advance.

[00127] 4b. If the UE is not inside any of the areas, the UE considers that there is no MBS broadcast service provided in the cell and may re-select to another cell if the cell has already been selected, and if the cell has not yet been selected, the UE does not consider the cell in cell selection or cell re-selection.

[00128] 4a. If the UE is inside any of the areas, the UE may consider the cell for cell selection or reselection.

[00129] 5. If the UE is inside one of the areas, the UE may camp on the cell and may monitor MCCH / MTCH for the MBS session and receives the MBS Broadcast Service.

[00130] The above steps 0-3 may also be one single step or single condition.

[00131] The area-defined MCCH configurations described above and the MBS session based areas may be combined to produce separate MCCH configurations and then further subdivided services. This can be seen in Figure 9, which illustrates geographical MBS session areas within a MCCH configuration area. In particular, two MCCH-Config areas are defined (MCCH-Config Area 1 and MCCH-Config Area 2) within the area of an NTN cell, and then within MCCH-Config Area 1, four MBS session service areas are defined (services areas of MBS-Sessions 1-4). Such an approach may provide additional flexibility in providing location specific MBS services.

[00132] In Example #2 (see end of disclosure), some examples are given how MBS-session based areas may be specified. In Example #2a, a parallel list of services areas for each service area defined in the MBS-Sessionlnfo-r17 is defined. In Example #2b, how it is specified in idle and inactive mode procedures can be seen.

[00133] As is known, the MBSBroadcastConfiguration may also contain a list of neighbour cells that provide the same MBS broadcast service. As an additional aspect of this disclosure, the MBSBroadcastConfiguration may also contain a list of neighbour cells, and their areas, that provide the same MBS broadcast service. Alternatively, the network can indicate that the MBS broadcast is provided in the same geographical area of a neighbouring cell. This can be indicated using a single bit. This can for instance mean that the neighbouring cell will also indicate serving the specific MBS service using the same geographical service area. Restricting Access via SIB21

[00134] In another example of how the access can be restricted, restrictions may be implemented by restricting access via SIB21.

[00135] This can be done by introducing areas related to a MBS Frequency Selection Area Identity (FSAI). In this case, the UE does not consider any MBS FSAI if the UE is not located in the area associated with an MBS FSAI. An example of how this can be implemented in the specifications can be seen in Example #3 (see end of disclosure). Network Updating MBS Information

[00136] In non-stationary satellite constellations, such as LEO and MEO, the satellite will move and its physical beams will sweep the earth. This means that the cells move along the surface of the earth. This is referred to as earth-moving beams.

[00137] In this case, the geographical areas used to restrict access to an MBS session would need to be updated. This is because it is more likely that the geographical areas for MBS sessions are fixed. In this case the network will constantly / regularly have to update the areas that it covers, and consequently the MBS services that are provided. This can be seen in Figures 10 and 11, where geographical service areas associated with MBS sessions change overtime as the NTN satellite (and corresponding coverage) moves. If the areas for MBS sessions are not fixed, the changed areas associated with an MBS session may be signalled / configuration information updated or information for determining the moving location of an area may be signalled to a UE such that the UE can track the changing area associated with an MBS session.

[00138] Referring to Figure 10, at a first point in time, service areas of MBS-Sessions 1-3 are provided by the NTN cell. However, referring to Figure 11, at a second subsequent second point in time, the coverage of the NTN cell has changed (due to movement of the satellite or other cell-providing entity). Consequently, at the second point in time, the service areas of MBS-Session 1 and MBS-Session 2 are no longer within the coverage of the NTN cell and thus no longer signalled. The service area of MBS-Session 2 is still within the coverage of the NTN cell and areas corresponding to two new MBS sessions are now within the coverage of the NTN cell: MBS-Session 3 and MBS-Session 4. Although Figures 10 and 11 have been described with reference to service areas of MBS sessions, similar may also apply to MCCH config areas based implementations, such that the areas defined by MCCH may be updated for moving NTN cells. Similar may also apply to the combination of MBS session areas and MCCH configuration areas.

[00139] In one example of the present disclosure, the network indicates when the MBS service will no longer continue for a specific geographical area for that specific cell. This can for instance be indicated via signalling a time when the service will be provided, or a time when the service is no longer provided. This time can for instance be used by a UE to determine whether to camp on a specific cell to receive the service or not. Note that this is different from providing the time when a service will start, as this indicates when the service will start or stop for a specific cell.

[00140] In an alternative example, the network provides conditions when the MBS service will no longer continue for a specific geographical area for that specific cell. This can for instance be in the form of an RSRP threshold, or a distance threshold (where the distance may be the Euclidean distance from the UE to the satellite location as determine via the ephemeris). Higher Layer Methods for Restricting Access

[00141] In an example of the present disclosure, the geographical service areas are conveyed by MBS User Service Description (USD), e.g. as a part of MBS User Service Announcement from the network to the UE. Thus the UE will evaluate whether it shall attempt to receive, or consider itself to be interested in a service.

[00142] In another example, the UE is given information about the geographical service area in a NAS message, which is then used by the UE when it considers whether a service is available or not. This can for instance be included in a PDU session establishment accept message, in the Received MBS Container. Or during UE registration procedures, e.g. initial registration or registration update, within the registration accept message. The network is able to determine UE’s rough location during the registration procedures, then the network may send UE the geographical service areas of the MBS service(s) based on UE location and / or UE interests.

[00143] A UE may also be indicated a start and stop timer for a specific MBS service of a specific geographical service area.

[00144] The above information may be included in a new container in the PDU (or MBS) session establishment accept message. This can for instance be named MBS geographical area container, indicated during the UE registration procedures, e.g. initial registration or registration update, within the registration accept message.

[00145] If the geographical MBS service area is signalled in NAS, then the MBS service area field in Received MBS Container may be ignored, or the signalled field may be empty.

[00146] If higher layer methods supply methods for restricting an MBS session or service in a specific area, the UE may / shall not attempt to perform any cell reselection methods to select a cell that provides the service unless the UE is inside the service area. In other words, the UE does not consider itself to be “interested in a service” if it is determined that the UE is not inside of the geographical area of a specific service.

[00147] The UE may also indicate the UE location in a Requested MBS container sent in a PDU session establishment request or during the registration procedures.

[00148] An example of such an approach is shown in Figure 12, which illustrates PDU session establishment including the MBS geographical service areas. In particular, in Figure, at S1250 the UE send a PDU session establishment request to the AMF 1204. Subsequently, in a PDU session establishment accept message sent by the AMF at S1252, information on one or more MBS geographical service is included. At S1254, the UE may then evaluate whether it is inside an MBS geographical service area. If the UE is within an MBS geographical service area, it may start receiving an MBS service. In Figure 12, the PDU session establishment request and accept can be replaced by registration (update) request and accept. Signaling MBS Interestindication

[00149] In another example of the present disclosure, the UE may signal the coarse location of the UE in an MBSInterestlndication. This location can be useful for the network to configure suitable MBS broadcast services. This is because if any of the above approaches are used, then when an NTN MBS sets up a new MBS broadcast service, i.e. starts broadcasting a new service, the service may need to be associated with an area. Thus UE providing location information is useful to configure the service. This approach can be seen in Figure 13, which illustrates including coarse location information in an MBSInterestlndication message sent to the network. However, location information of any required accuracy may be provided, possibly depending on characteristics of the MBS services, characteristics of the UE, and / or privacy-related aspects for example.

[00150] In particular, in Figure 13 at S1350 an MBSInterestlndication is sent from a UE 1302 to an gNB 1304, where the MBSInterestlndication includes location information of the UE. At S1352, the gNB may then activate services based on the UE location. Such an approach may also be useful for multicast scenarios since the network will have indication of the UEs to configure the multicast for.

[00151] The MBSInterestlndication can for instance be configured to be triggered if the UE wants to access a service, but the service is outside of the geographical service area.

[00152] In an alternative, the UE may instead of indicating the UE location, indicate that the UE does currently not have access to the service in its location, i.e. the UE is outside of the service location.

[00153] It may also be such that the UE is not allowed to indicate interest in a service if the service is not provided in a geographical service area.

[00154] An example of use of the MBSInterestlndication can be implemented in the specifications can be seen in Example #4 (see end of disclosure). Inter-node Signalling

[00155] In another example of the present disclosure, the MBS service area in NTN may alternatively consist of NTN related information beyond a geographical area. It may for instance consist of the virtual cells, virtual TAs (also named NR NTN TAI) and the virtual PLMNs. This can be used for inter-node signaling, such as signaling between 5GC and RAN, for instance NGAP interface, orXn interface.

[00156] The above may be useful as the 5GC and RAN uses the virtual PLMN, virtual TAs and virtual cells, which are fixed on the ground, while the signalled PLMNs and cells on the Uu interface may be moving.

[00157] The above means that the NTN MBS service areas that are used in the core network and in-between gNBs (overXn interface) are then translated by the RAN to a geographical area, which is then signalled over the Uu interface (in system information etc as discussed above). Such an approach can be seen in Figure 14, which illustrates using virtual NTN identifiers between gNB and AMF and geographical area over Uu (between UE and gNB).

[00158] With reference to Figure 14, at step S1450, the AMF 1406 and gNB 1404 use virtual NTN TAIs and cells to define NTN MBS Service area(s). At step S1452, the gNB computes the geographical MBS Service area(s) based on NTN MBS Service based on virtual NTN TAIs and CelllDs. At step S1554 the gNB transmits information on the service area(s) to a UE 1402. The UE may then receive a related MBS service.

[00159] The NTN MBS service area, or the virtual MBS service area can be signalled in the following messages for NGAP interface: - BROADCAST SESSION SETUP and BROADCAST SESSION MODIFICATION - BROADCAST SESSION MODIFICATION REQUEST and BROADCAST SESSION MODIFICATION RESPONSE - HANDOVER REQUEST or HANDOVER REQUIRED

[00160] The NTN MBS service area, or the virtual MBS service area can be signalled in the following messages forXn interface: - HANDOVER REQUEST and HANDOVER REQUEST ACKNOWLEDGE - XN-U ADDRESS INDICATION - MULTICAST GROUP PAGING

[00161] The geographical service areas may also be conveyed by the gNB to the AMF or from AMF to the gNB.

[00162] Certain examples of the present disclosure may be provided in the form of an apparatus / device / network entity configured to perform one or more defined network functions and / or a method therefor. Such an apparatus / device / network entity may comprise one or more elements, for example one or more of receivers, transmitters, transceivers, processors, controllers, modules, units, and the like, each element configured to perform one or more corresponding processes, operations and / or method steps for implementing the techniques described herein. For example, an operation / function of X may be performed by a module configured to perform X (or an X-module). Certain examples of the present disclosure may be provided in the form of a system (e.g., a network) comprising one or more such apparatuses / devices / network entities, and / or a method therefor.

[00163] It will be appreciated that examples of the present disclosure may be realized in the form of hardware, software or a combination of hardware and software. Certain examples of the present disclosure may provide a computer program comprising instructions or code which, when executed, implement a method, system and / or apparatus in accordance with any aspect, example and / or embodiment disclosed herein. Certain embodiments of the present disclosure provide a machine-readable storage storing such a program.

[00164] Figure 15 is a block diagram of an exemplary network entity / function that may be used in examples of the present disclosure, such as the techniques disclosed in relation to any of the preceding figures. For example, any of the network entities, network function etc. (e.g. UE, BS, gNB / eNB, ATG entities, NTN nodes, etc.) may be provided in the form of the network entity illustrated in Figure 15. The skilled person will appreciate that a network entity / function may be implemented, for example, as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, and / or as a virtualised function instantiated on an appropriate platform, e.g. on a cloud infrastructure.

[00165] The entity 1500 comprises a processor (or controller) 1501, a transmitter 1503 and a receiver 1505. The receiver 1505 is configured for receiving one or more messages from one or more other network entities, for example as described above. The transmitter 1503 is configured for transmitting one or more messages to one or more other network entities, for example as described above. The processor 1501 is configured for performing one or more operations, for example according to the operations as described above.

[00166] It will be appreciated that, in each example / embodiment / aspect etc. described above, one or more features or operations may be omitted, modified or moved (e.g., to change the order of the features or the operations), if desired and appropriate.

[00167] Additionally, where the figures illustrating example method flows include text in relation to a specific step / operation, it will be appreciated that this text is simply an example of the corresponding step / operation, where a more general definition (such as may be found in the description of the corresponding step) may apply for the step / operation.

[00168] Additionally, regarding all of the above, one or more features or operations etc. from any example / embodiment may be combined with features or operations from any other example / embodiment. That is, the present disclosure should be considered to include all combinations of examples / embodiments disclosed herein, as appropriate, as well as combinations of individual features within and between each example / embodiment, as appropriate.

[00169] The techniques described herein may be implemented using any suitably configured apparatus and / or system. Such an apparatus and / or system may be configured to perform a method according to any aspect, embodiment or example disclosed herein. Such an apparatus may comprise one or more elements, for example one or more of receivers, transmitters, transceivers, processors, controllers, modules, units, and the like, each element configured to perform one or more corresponding processes, operations and / or method steps for implementing the techniques described herein. For example, an operation / function of X may be performed by a module configured to perform X (or an X-module). The one or more elements may be implemented in the form of hardware, software, or any combination of hardware and software.

[00170] It will be appreciated that examples of the present disclosure may be implemented in the form of hardware, software or any combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage, for example a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape or the like.

[00171] It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs comprising instructions that, when executed, implement certain examples of the present disclosure. Accordingly, certain examples provide a program comprising code for implementing a method, apparatus or system according to any example, embodiment and / or aspect disclosed herein, and / or a machine-readable storage storing such a program. Still further, such programs may be conveyed electronically via any medium, for example a communication signal carried over a wired or wireless connection.

[00172] While the disclosure has been shown and described with reference to certain examples, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the disclosure.

[00173] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. Example Changes to Specifications Example #1 -SIB20 restriction Example #la - RRC Changes to specification 38.331 in bold. The changes introduced in the ASN.l does the following: ............. ...................... Example based on 38.331 V18.CW.................................... 5.9.2.3 MCCH information acquisition by the UE An MBS capable UE interested to receive or receiving an MBS broadcast service shall: 1> if the procedure is triggered by an MCCH information change notification: 2> start acquiring tEcMBSBroadcastConfiguration message on MCCH in the concerned cell from the slot in which the change notification was received; 1> if the UE enters a cell providing SIB20 and there is no serviceArea configured for any of the MCCH; or 1> if the UE enters a cell providing SIB20 and there is a serviceArea configured for an MCCH that the UE location is inside of; or 1> if the UE receives sCellSIB20: 2> acquire theMBSBroadcastConfiguration message on MCCH in the concerned cell at the next repetition period. SIB20 SIB20 contains the information required to acquire the MCCH / MTCH configuration for MBS broadcast. SIB20 information element ri-L hti lib rpp-r utml r t h-I IT' H-11~ .. , llliillllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllli Conf moih-Rtp'^titiciiFii’icpidndOf f 5^1-11^ HCC'H-R^pt'tit.ionF^riC'dTmdOf f , hidcbi-WindC'VrDuratidn-rl" IF'1 0u {sli, ^14, s!8, sllu, sliO, =:140,=:160, 111 h~H 1111 dll llF-ll 1*11" {iXr 114f 11^, 1111 r It v, It* 4, 111^ ilpOO;3333333333333333333333333333333333333333330 l£( rr (1 11512, 111024, 1'12045, 1'14056, 115102, 1116554,; II >H-F-=^-titi iiF^n< l-ii 1 llllllllflllllllllllllllll^^ ililillllllililili^ !!!llllll^!!!!!!! |i|i|tiil|H|:|:|:| :i0:100l;0^0| >M, .. ' , U). .I-". f / 5.,255) Example #lb - idle and inactive mode procedures If the MBS broadcast capable UE is receiving or interested to receive an MBS broadcast service(s) and can only receive this MBS broadcast service(s) by camping on a frequency on which it is provided, the UE may consider that frequency to be the highest priority during the MBS broadcast session as specified in TS 38.300 [2] as long as the three following conditions are fulfilled: 1) SIB1 scheduling information of the cell reselected by the UE due to frequency prioritization for MBS contains SIB20; 2) Either: - One or more MBS FSAI(s) of that frequency is indicated in SIB21 of the serving cell and the same MBS FSAI(s) is also indicated for this MBS broadcast service in MBS User Service Description (USD) as specified in TS 26.346

[20] , or - SIB21 is not provided in the serving cell and that frequency is included in the USD of this service, or - SIB21 is provided in the serving cell but does not provide the frequency mapping for the concerned service, and that frequency is included in the USD of this service. 3) If the MCCH is configured with an an area and the UE is inside one of the MCCH configuration areas as defined by SIB20 NOTE 0g: It is up to UE implementation which frequency to select, when the USD provides multiple frequencies for the service the UE is interested in. If the MBS broadcast capable UE is receiving or interested to receive an MBS broadcast service, the UE may consider cell reselection candidate frequencies at which it cannot receive the MBS broadcast service to be of the lowest priority during the MBS broadcast session as specified in TS 38.300 [2], as long as SIB1 scheduling information of the cell contains SIB20 on the MBS frequency which the UE monitors and as long as the condition 2) above is fulfilled for the serving cell. NOTE Oh: Example scenarios in which such down-prioritisation may be needed include the cases where camping is not possible for the UE on the MBS broadcast frequency (e.g. the MBS broadcast frequency belongs to a PLMN different from UE's registered PLMN) while the UE can receive the MBS broadcast service when camped on another frequency than the MBS broadcast frequency or current frequency. NOTE Oi: The frequency prioritization for MBS broadcast, NR sidelink communication, or V2X sidelink communication may override the re-selection priorities for slice-based cell reselection. Example #2 - MBSBroadcastConfiguration Example #2a - RRC Changes to specification 38.331 in bold. The changes introduced in the ASN.l does the following 5.9.3.2 Initiation The UE applies the broadcast MRB establishment procedure to start receiving an MBS session of an MBS broadcast service it is interested in. The procedure may be initiated e.g. upon start of the MBS session, upon entering a cell providing an MBS broadcast service the UE is interested in, upon becoming interested in the ongoing MBS broadcast service, upon removal of the UE capability limitations inhibiting reception of the ongoing MBS broadcast service UE is interested in. If the MBS session has a configured area, the UE only initiates the procedure if the UE location is inside the MBS session area. The UE applies the broadcast MRB release procedure to stop receiving a session of an MBS broadcast service. The procedure may be initiated e.g. upon stop of the MBS session, upon leaving the cell broadcasting the MBS service the UE is interested in, upon losing interest in the MBS service, when capability limitations start inhibiting reception of the concerned service. - MBSBroadcastConfiguration The MBSBroadcastConfiguration message contains the control information applicable for MBS broadcast services transmitted via broadcast MRB. Signalling radio bearer: N / A REC-SAP: UM Logical channel: MCCH Direction: Network to UE MBSBroadcastConfiguration message cr i tic si Ext =-n ci c- ns nibcBrcadcact Ccnfiguxativn-i’l'l nritisalExtcncicncFutur- ggg|l|gggggggggggg^^ FiFiOllifFg IIBEBrccd'ScstConficurction-rll-IEc : : = n'i'C-EcccionlnfC'Lict-r 1" drx-lonf igF TI 1-Li c t-r 17 E'F -- -iiW1F 111-t 414 , pdcch-Cdnfigl ITCH-rl" lllllllllOiddd&OtOggdddO FFFFFFgOsBlFgWWiOOOiW ntTiCriticclExtcn =:itn HBF-K.=_i..nlht Li-t-rl , HBS-HcighhccirCcllLict-vl? <ddrd:?d.f ll'ldl'd t (m.E (I. .nrasNr^^ OF FFCCH-E nil fBr aLibd-il" ' , MT- H-^LB-IL-iH Ll^t-il" ' , FFFFFF:;noiic£xt±caiExtiensi^ _____________________________MBSBroadcastConfigu ration field descriptions_____________________________ pdsch-ConflgMfCH Provides parameters for acquiring the PDSCH for MTCH. When this field is absent, the UE shall use parameters in pdsch-ConfigMCCH to acquire the PDSCH for MTCH.____________________________________________________ mbs-SessionlnfoList Provides the configuration of each MBS session provided by MBS broadcast in the current cell. If rss®- mbs-NeighbourCellList List of neighbour cells providing one or more MBS broadcast services via broadcast MRB that are provided by the current cell. This field is used by the UE together with mtch-NeighbourCell field signalled for each MBS session in the corresponding MBS-Sessionlnfo. When an empty mbs-NeighbourCellList list is signalled, the UE shall assume that MBS broadcast services signalled in mbs-SessionlnfoList in the MBSBroadcastConfiguration message are not provided in any neighbour cell. When a non-empty mbs-NeighbourCellList is signalled, the current serving cell does not provide information about MBS broadcast services of a neighbour cell that is not included in mbs-NeighbourCellList, i.e., the UE cannot determine the presence or absence of an MBS service of a neighbour cell that is absent. When the field mbs-NeighbourCellList is absent, the current serving cell does not provide information about MBS broadcast services in the neighbouring cells, i.e. the UE cannot determine the presence or absence of an MBS service in neighbouring cells based on the absence of this field. MBS-SessionlnfoList The IE MBS-SessionlnfoList provides the list of ongoing MBS broadcast sessions transmitted via broadcast MRB and, for each MBS broadcast session, the associated G-RNTI and scheduling information. MBS-SessionlnfoList information element :OgF§OiO$^FF|dSlisiOi^FF^FOFFFFFFFFFOOFWFFFg^l^ FS^^idFiFlFlliFiW^FdiFgigFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF^ ulhtk-11" :: = icnld-rl 7 mrt’-Li tfBiX'ti z-ort-rl" mtcFi-SoI^odulinglnfo-r 1" :7x^d77d7777777777777777777777 IIIIIIlElpdOlOOlOOO 10*7:17:7:7:7:7:7:7:7:7:7:7:77 11110077777777777777^ l IFOLiotBrotdrttf-rl", D RI L-Cu n f i g FT1I-1 ndor- r 17 E DTCH-Configlnd^x-rl~ 144414444004440444140^ BFZ-7‘:TifigFTH~Indo:i~rl~ : : = EDSCH-ConfigInd^x-rlM ::= 00111i7W170000O00O0^^^O1^^777: 11JTECl? (g . .in^dtofEDSCH-CcOigETM-l-rl? / 1 IT> H-S 2B-I bp m [Um 1 ' In-i 1 ipTpdpWiiprEgiQil^OOOdSOEOiO;^^^ HFB-Li_fBt al -ut-11 :: = I nf oErc adr art -r 17 1 IFB-InfC'Broadraat-rl^ : : = IddllliWlp 14*777*77777: rlr-Config-rl" 101107^4^7^7^7^7^ MRB~BDCF'~i'onfigBroadoaot=rl", I IF B-FLO-O . nfigBr. a 7L art-r 1" , IOIOO0OOII4000 40 414114 7:7:7770004S4104440 :R:<:E:g7E:7:7s777777777777777777777777777777777777777777777777777777777777777 h~sd~rCca7ipr~3^icn~rl~ 7:7:7:7:7:7:7:7:70000777777777777777777777777777; 7777777777777777770010*7777777777777777777777777777777777777777777777 lllllllliotiiiiiiiii eEeEeEeEeEeEeEeEieoOOI^^ pro til el?: 0 U 0 t-r 17 EEEEEEEEEEEEEEEEEEEEE profit=Ox u 00 2-r17 sssS'OhHOcBOsSSSO^SSsssssS IIlOO' 111^ O r ' ■} ... KSIS^^ lOg777;7s DEFAULT IF, FMMEJV.7.W {nisi, inslO, ms4u, mslEU, msFOu, mslOUC1, 1 ogi salCh anne 11 dent ity-r IF Logicaldhannellderit it’ / , 22:0007:07:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7777^ 777:7:71^0100111440^:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:7:72 iiiiiiiiiiiiiiiiiiiiiiiiii MBS-SessionInfoList-vl900 : := $::'O$U:Ct'C$;l (1. .maxNrofMBS-Session-rl7) ) ••»< MBS- MBS-Sessionlnf 6O;i£19;;;;d;i:47;7;7 |4|;:;O^4444^4444444444444 iiiiiiiiiiiiiiii _______________________________MBS-SessionlnfoList field descriptions_______________________________ g-RNTI G-RNTI used to scramble the scheduling and transmission of MTCH.______________________________________ headercompression \t rohc is configured, the UE shall apply the configured ROHC profile(s) in downlink._____________________________ mbs-Sessionld Indicates an identifier of the MBS session provided by the MTCH.____________________________________________ mrb-listBroadcast A list of broadcast MRBs to which the associated broadcast MBS session is mapped to._______________________ mtch-neighbourCell Indicates neighbour cells which provide this service on MTCH. The first bit is set to 1 if the service is provided on MTCH in the first cell in mbs-NeighbourCellList, otherwise it is set to 0. The second bit is set to 1 if the service is provided on MTCH in the second cell in mbs-NeighbourCellList, and so on. If the service is not available in any neighbouring cell and mbs-NeighbourCellList is signalled, the network sets all bits in this field to 0. The field is absent when mbs-NeighbourCellList is absent or an empty mbs-NeighbourCellList is signalled. If this field is absent when mbs-NeighbourCellList is absent or a non-empty mbs-NeighbourCellList is signalled, the related service may or may not be available in any neighbouring cell, i.e. the UE cannot determine the presence or absence of an MBS service in neighbouring cells based on the absence of this field. If this field is absent and an empty mbs-NeighbourCellList is signalled, then the UE shall assume that MBS broadcast services signalled in mbs-SessionlnfoList in the MBSBroadcastConfiguration message are not provided in any neighbour cell. mtch-schedulinglnfo Indicates the index of DRX configuration entry in drx-ConfigPTM-List that is used for scheduling the MTCH. The value 0 corresponds to the first entry in drx-ConfigPTM-List, the value 1 corresponds to the second entry in drx-ConfigPTM-Listand so on. In case mtch-schedulinglnfo is absent fora G-RNTI (i.e. no PTM DRX), the UE shall monitor for PDCCH scrambled with G-RNTI in any slot according to the search space configured for MTCH [see TS 38.213

[13] , clause 10.1]._______________ mtch-SSB-MappingWindowIndex Indicates the index of MTCH-SSB-MappingWindowCycleOffset configuration entry in MTCH-SSB- MappingWindowList. The value 0 corresponds to the first entry in MTCH-SSB-MappingWindowList, the value 1 corresponds to the second entry in MTCH-SSB-MappingWindowList and so on. This field is set to the same value for all MBS sessions mapped to the same G-RNTI._________________________________________________ pdcp-SN-SizeDL Indicates that PDCP sequence number size of 12 bits is used, as specified in TS 38.323 [5], When the field is absent the UE applies the value as specified in 9.1.1.7._________________________________________________________ pdschConfiglndex Indicates the index of PDSCH configuration entry in pdschConfigList for MTCH. Value 0 corresponds to the first entry in pdschConfigList, the value 1 corresponds to the second entry in pdschConfigList and so on. When the field is absent the UE applies the first entry in pdschConfigList for MTCH. sn-FieldLength Indicates that the RLC SN field size of 6 bits is used, see TS 38.322 [4], When the field is absent the UE applies the value as specified in 9.1.1.7.____________________________________________________________________________ t-Reassembly Timer for reassembly in TS 38.322 [4], in milliseconds. Value msO means 0 ms, value ms5 means 5 ms and so on. When the field is absent the UE applies the value in specified in 9.1.1.7.___________________________________ t-Reordering Value in ms oft-Reordering specified in TS 38.323 [5], Value ms1 corresponds to 1 ms, value ms10 corresponds to 10 ms, and so on. When the field is absent the UE applies the value as specified in 9.1.1.7. Example #2b - idle and inactive mode procedures If the MBS broadcast capable UE is receiving or interested to receive an MBS broadcast service(s) and can only receive this MBS broadcast service(s) by camping on a frequency on which it is provided, the UE may consider that frequency to be the highest priority during the MBS broadcast session as specified in TS 38.300 [2] as long as the three following conditions are fulfilled: 1) SIB1 scheduling information of the cell reselected by the UE due to frequency prioritization for MBS contains SIB20; 2) Either: - One or more MBS FSAI(s) of that frequency is indicated in SIB21 of the serving cell and the same MBS FSAI(s) is also indicated for this MBS broadcast service in MBS User Service Description (USD) as specified in TS 26.346

[20] , or - SIB21 is not provided in the serving cell and that frequency is included in the USD of this service, or - SIB21 is provided in the serving cell but does not provide the frequency mapping for the concerned service, and that frequency is included in the USD of this service. 3) If a service area is configured for MBS session, the UE is inside the service area as defined by the MBS session in MBSBroadcastConfiguration NOTE 0g: It is up to UE implementation which frequency to select, when the USD provides multiple frequencies for the service the UE is interested in. If the MBS broadcast capable UE is receiving or interested to receive an MBS broadcast service, the UE may consider cell reselection candidate frequencies at which it cannot receive the MBS broadcast service to be of the lowest priority during the MBS broadcast session as specified in TS 38.300 [2], as long as SIB1 scheduling information of the cell contains SIB20 on the MBS frequency which the UE monitors and as long as the condition 2) above is fulfilled for the serving cell. NOTE Oh:Example scenarios in which such down-prioritisation may be needed include the cases where camping is not possible for the UE on the MBS broadcast frequency (e.g. the MBS broadcast frequency belongs to a PLMN different from UE's registered PLMN) while the UE can receive the MBS broadcast service when camped on another frequency than the MBS broadcast frequency or current frequency. NOTE Oi: The frequency prioritization for MBS broadcast, NR sidelink communication, or V2X sidelink communication may override the re-selection priorities for slice-based cell reselection. Example #3 - SIB21 Example #3a - SIB21 Changes to specification 38.331 in bold. SIB21 SIB21 contains the mapping between the current and / or neighbouring carrier frequencies and MBS Frequency Selection Area Identities (FSAI). SIB21 information element ittoa-FSAI -1 nt raFrnq-rl 7 I IEF-FSAI-Liat-nl~ m]?£-F£AI-Intei'Fu^qList-r I"7 I IBS-FS^J-Int e'rFreqLi^t-ul ihhhhhhhhhhii4hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh8 ?ssss:0S:6SOsS:S8fiB:gs®i:SssssssssssfiKOfisOj:O0: / ssss^ sss?ssOB8®8fBBO8ssssssssssssssOB80B:E8B8B8ssssss Blilililililililililililililililililililililililililil :OssOB4(Os?ssBsI08A1sSsSsSsSsSsSsSs jisjsjsjsjsjsseiivTc^^e&KsfeitsftcsEdcaSidtysjsjsi&feitsttcsiiS^^ __________________________________________SIB21 field descriptions______________________________________ mbs-FSAI-lnterFreqUst Contains a list of neighboring frequencies including additional bands, if any, that provide MBS services and the corresponding MBS FSAIs. If mbs-FSAI-lnterFreqList-v1900 is present, they shall contain the same number of entries, listed mbs-FSAi-lntraFreq Contains the list of MBS FSAIs for the current frequency. For MBS service continuity, the UE shall use all MBS FSAIs listed in mbs-FSAI-lntraFreq to derive the MBS frequencies of interest.________________________________ mbs-FSAFServiceArea Contains the list of MBS FSAIs for the current frequency. serviceArea_______________________________________ Example #3b - SIB21 If the MBS broadcast capable UE is receiving or interested to receive an MBS broadcast service(s) and can only receive this MBS broadcast service(s) by camping on a frequency on which it is provided, the UE may consider that frequency to be the highest priority during the MBS broadcast session as specified in TS 38.300 [2] as long as the three following conditions are fulfilled: 1) SIB1 scheduling information of the cell reselected by the UE due to frequency prioritization for MBS contains SIB20; 2) Either: - One or more MBS FSAI(s) of that frequency is indicated in SIB21 of the serving cell and the same MBS FSAI(s) is also indicated for this MBS broadcast service in MBS User Service Description (USD) as specified in TS 26.346

[20] , or - SIB21 is not provided in the serving cell and that frequency is included in the USD of this service, or - SIB21 is provided in the serving cell but does not provide the frequency mapping for the concerned service, and that frequency is included in the USD of this service. 3) If SIB21 is broadcast and a service area is configured with the MBS FSAI, the UE is located inside of the service NOTE Og: It is up to UE implementation which frequency to select, when the USD provides multiple frequencies for the service the UE is interested in. If the MBS broadcast capable UE is receiving or interested to receive an MBS broadcast service, the UE may consider cell reselection candidate frequencies at which it cannot receive the MBS broadcast service to be of the lowest priority during the MBS broadcast session as specified in TS 38.300 [2], as long as SIB1 scheduling information of the cell contains SIB20 on the MBS frequency which the UE monitors and as long as the condition 2) above is fulfilled for the serving cell. NOTE Oh:Example scenarios in which such down-prioritisation may be needed include the cases where camping is not possible for the UE on the MBS broadcast frequency (e.g. the MBS broadcast frequency belongs to a PLMN different from UE's registered PLMN) while the UE can receive the MBS broadcast service when camped on another frequency than the MBS broadcast frequency or current frequency. NOTE Oi: The frequency prioritization for MBS broadcast, NR sidelink communication, or V2X sidelink communication may override the re-selection priorities for slice-based cell reselection. Example #4 MBSInterestlndication The MBSInterestlndication message is used to inform network that the UE is receiving / interested to receive or no longer receiving / interested to receive MBS broadcast service(s) via a broadcast MRB. Signalling radio bearer: SRB1 REC-SAP: AM Logical channel: DCCH Direction: UE to Network MBSInterestlndication message HBl’Int-i'i^t In 31 riti m-vl31"1 ::= . ’ { nJ .-11 113-1---111(1111.1,1^-11^ MB.-II iiiMi^inijInl Ll.t-il'- . ' MBSInterestlndication field descriptions mbs-FreqUsi List of MBS frequencies on which the UE is receiving or interested to receive MBS broadcast service via a broadcast MRB. mbs-NonServinglnfoList Indicates information for MBS broadcast reception on the non-serving cell. mbs-Priority Indicates whether the UE prioritises MBS broadcast reception above unicast and MBS multicast reception. The field is present (i.e. value true), if the UE prioritises reception of broadcast services, on frequencies indicated in mbs-FreqList, above a reception of any of the unicast bearers and multicast MRBs. Otherwise the field is absent. mbs-ServiceUsi List of MBS broadcast services which the UE is receiving or interested to receive. Acronyms and Definitions 3GPP 3rd Generation Partnership Project 5G 5th Generation 5GC 5G Core 5QI 5G QoS Identifier 5GS 5G System 5GSM 5G System Session Management 5GMM 5G System Mobility Management AF Application Function Al Artificial Intelligence AM Acknowledged Mode AMF Access and Mobility Management Function AS Access Stratum ASP Application Service Provider ATG Air-To-Ground AUSF Authentication Server Function CDN Content Delivery Network DCAF Data Collection Application Function DNAI Data Network Access Identifier DNN Data Network Name DNS Domain Name Server DRB Data Radio Bearer eNB Evolved Node B EPC Evolved Packet Core FEC Forward Error Correction FQDN Fully Qualified Domain Name GBR Guaranteed Bit Rate gNB Next generation Node B GPSI Generic Public Subscription Identifier HSS Home Subscriber Service IAB Integrated Access and Backhaul ID Identity / ldentifier lloT Industrial Internet of Things IMEI International Mobile Equipment Identities IP Internet Protocol l-SMF Intermediate SMF LADN Local Area Data Network LL SSM Lower Layer SSM MBMS Multimedia Broadcast / Multicast Service MBS Multicast / Broadcast Service MBSF Multicast / Broadcast Service Function MBSTF Multicast / Broadcast Service Transport Function MB-SMF Multicast / Broadcast Session Management Function MB-UPF Multicast / Broadcast User Plane Function MCCH Multicast Control Channel MTCH Multicast Traffic Channel ML Machine Learning MME Mobility Management Entity MN Master Node MNF Monitoring Network Function MNO Mobile Network Operator MT Mobile Termination NAS Non-Access Stratum NEF Network Exposure Function NRF Network Repository Function NG-RAN Next Generation Radio Access Network NG-eNB Next Generation eNB NGAP Next Generation Application Protocol NSA Non-Standalone NSSF Network Slice Selection Function NTN Non-Terrestrial Networks NW Network NWDAF Network Data Analytics Function OS Operating System OSAPP OS Application PCF Policy Control Function PCO Protocol Configuration Options PDR Packet Detection Rule PDU Protocol Data Unit PLMN Public Land Mobile Network PTM Point To Multipoint PTP Point to Point QFI QoS Flow Identifier (ID) QoS Quality of Service RACH Random Access Channel RAN Radio Access Network RRC Radio Resource Control RSD Route Selection Descriptor SA Standalone SDAP Service Data Adaptation Protocol SDU Service Data Unit SGW Serving Gateway SIM Subscriber Identity Module SLA Service Level Agreement SM Session Management SMF Session Management Function SN Secondary Node S-NSSAI Single Network Slice Selection Assistance Information SSB Synchronization Signal Block SSM Source Specific IP Multicast address SSC Session and Service Continuity SRB Signaling Radio Bearer SUPI Subscription Permanent Identifier TA Tracking Area TAI Tracking Area Identity TE Terminal Equipment TM Transparent Mode TMGI Temporary Mobile Group Identity TS Technical Specification UAV Unmanned Aerial Vehicle UDM Unified Data Manager UDR Unified Data Repository UE User Equipment UL Uplink UM Unacknowledged Mode UP User Plane UPF User Plane Function URLLC Ultra-Reliable and Low-Latency Communication URSP UE Route Selection Policy

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