Managing paging for multicast services

Abstract

A paging method is implemented in a node of a radio access network (RAN) and comprises: receiving a message comprising an identifier of a multicast and / or broadcast service (MBS) session; and paging a user equipment (UE) using information in the message in response to determining that the message includes a paging list.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of the filing date of provisional U.S. patent application No. 63 / 371,632, entitled “Managing Paging for Multicast Services,” filed on August 16, 2022. The entire contents of the provisional application are hereby expressly incorporated herein by reference. Technical Field

[0003] The present disclosure relates to wireless communications, and more particularly to paging a UE for one or more multicast and / or broadcast services (MBS). Background Art

[0004] The background description provided herein is for the purpose of generally presenting the context of the present disclosure. The work of the presently named inventors (to the extent that it is described in this background section) and aspects of this description that may not have been identified as prior art at the time of filing are neither explicitly nor implicitly admitted to be prior art against the present disclosure.

[0005] In a telecommunication system, the Packet Data Convergence Protocol (PDCP) sublayer of the radio protocol stack provides services such as user plane data delivery, encryption, integrity protection, etc. For example, the PDCP layer defined for the Evolved Universal Terrestrial Radio Access (EUTRA) radio interface (see 3GPP specification TS 36.323) and New Radio (NR) (see 3GPP specification TS 38.323) provides sequencing of protocol data units (PDUs) in the uplink direction (from a user device (also referred to as user equipment (UE)) to a base station) and in the downlink direction (from a base station to a UE). Further, the PDCP sublayer provides services of signaling radio bearers (SRBs) to the radio resource control (RRC) sublayer. The PDCP sublayer also provides services of data radio bearers (DRBs) to the service data adaptation protocol (SDAP) sublayer or protocol layers such as the Internet Protocol (IP) layer, the Ethernet protocol layer, and the Internet Control Message Protocol (ICMP) layer. Generally speaking, a UE and a base station may use SRBs to exchange RRC messages and non-access stratum (NAS) messages, and may use DRBs to transmit data on a user plane.

[0006] Base stations operating in accordance with the fifth generation (5G) New Radio (NR) requirements support significantly larger bandwidths than fourth generation (4G) base stations. Therefore, the Third Generation Partnership Project (3GPP) has proposed that for Release 15, the user equipment unit (UE) supports a 100 MHz bandwidth in frequency range 1 (FR1) and a 400 MHz bandwidth in frequency range (FR2). Due to the relatively wide bandwidth of typical carriers, 3GPP has proposed for Release 17 that 5G NR base stations can provide multicast and / or broadcast services (MBS) to UEs, which can be useful in many content delivery applications such as transparent IPv4 / IPv6 multicast delivery, IPTV, wireless software delivery, group communications, IoT applications, V2X applications, and emergency messages related to public safety.

[0007] In order to provide multicast and / or broadcast services (MBS), the base station can configure common frequency resources (CFR) for multiple UEs and configure a group common physical downlink control channel (PDCCH) configuration. The base station can assign a group common radio network temporary identifier (RNTI) to these UEs to receive a physical downlink shared channel (PDSCH) transmission including MBS data packets. The base station can then send downlink control information (DCI) with a cyclic redundancy check (CRC) scrambled by the group common RNTI on the group common PDCCH to schedule PDSCH transmissions including MBS data packets.

[0008] When there is (usually temporarily) no data for the RAN to send to the UE for a multicast MBS session, the RAN may transition the UE to the RRC_IDLE or RRC_INACTIVE state. When the CN activates a multicast MBS session, the RAN notifies the UE in the RRC IDLE or INACTIVE state by sending a paging message for the multicast MBS session. After receiving the paging message, the UE reconnects to the RAN and transitions to the RRC_CONNECTED state.

[0009] However, it is unclear how the RAN determines the paging occasion and paging frame for sending the paging message. It is also unclear how the CN pages UEs operating in different 5G MM modes for multicast MBS sessions. In addition, according to the current 3GPP specification 24.501, when the UE operates in 5G MM-IDLE mode, the UE responds to paging for the MBS session (e.g., a paging indication including a temporary mobile group identity (TMGI)). However, when a UE in 5G MM-CONNECTED mode and an RRC inactivity indication receives paging for the MBS session, the UE does not respond to the paging. Therefore, the UE is unable to receive MBS data for the MBS session.

[0010] Further, when a UE in 5G MM-CONNECTED mode and RRC inactivity indication receives a paging message for an MBS session, the UE transitions to 5G MM-IDLE mode in some cases because the UE is unable to determine whether the paging message including the MBS session ID is a RAN paging message or an AMF paging message.

[0011] Furthermore, when the base station is distributed and thus includes a central unit (CU) and at least one distributed unit (DU), it is unclear how the DU determines a paging occasion and / or a paging frame in response to an interface message related to an MBS session. Summary of the invention

[0012] An example embodiment of the technology of the present disclosure is a paging method implemented in a node of a radio access network (RAN). The method includes: receiving a message including an identifier of a multicast and / or broadcast service (MBS) session; and in response to determining that the message includes a paging list, paging a user equipment (UE) using information in the message.

[0013] Another example embodiment of the techniques is a radio access network (RAN) node comprising: a transceiver; and processing hardware configured to implement the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1A is a block diagram of an example wireless communication system in which a RAN and / or a UE implement the techniques of the present disclosure for managing transmission and reception of MBS;

[0015] Figure 1B Yes, you can Figure 1A A block diagram of an example base station including a central unit (CU) and a distributed unit (DU) operating in a system of FIG.

[0016] Figure 2A is a block diagram of an example protocol stack, Figure 1A to Figure 1B The UE may communicate with the base station according to the example protocol stack;

[0017] Figure 2B is a block diagram of an example protocol stack, Figure 1A to Figure 1B The UE may communicate with the DU and CU of the base station according to the example protocol stack;

[0018] Figure 3 to Figure 4 is an example message sequence in which a base station sends one or more paging messages to page a UE operating in an inactive state for an MBS session, and the UE activates MBS reception to receive the MBS session in response to receiving the paging messages;

[0019] Figures 5 to 9C is a flow chart of an example method for paging a UE for an MBS session, which example method may be implemented by a core network (CN) node;

[0020] Figures 10 to 13B is a flow chart of an example method for paging a UE for an MBS session, which example method may be implemented by one or more RAN nodes (e.g., a non-distributed base station or a distributed base station including a CU and a DU);

[0021] Figure 14 to Figure 15 is a flow chart of an example method for receiving a paging message for an MBS session, which example method may be implemented by a UE. DETAILED DESCRIPTION

[0022] In general, the techniques of the present disclosure allow a UE to receive MBS information via radio resources allocated by a base station of a RAN. To this end, a base station may configure different radio resources in one or more overlapping cells to multicast or broadcast MBS data (and associated control information) and / or unicast non-MBS data (and associated control information) with one or more UEs on a downlink (DL). It should be noted that "sending" by a base station may refer interchangeably to "multicast", "broadcast" and / or "unicast". A base station may also unicast MBS data (and associated control information) to a UE on a dedicated DRB for the UE. One or more UEs may send non-MBS data to a base station on an uplink (UL).

[0023] Therefore, the base station of the present disclosure may configure one or more radio bearers to send MBS information (i.e., MBS data packets and / or control information) to the UE. The radio bearer that carries the MBS information to the UE may be a unicast DRB (i.e., a dedicated DRB for the UE) or a multicast DRB (i.e., a DRB that can be shared by multiple UEs, also referred to as an MBS radio bearer or MRB). For example, the base station may send a unicast configuration parameter or a multicast configuration parameter to the UE to configure the UE to receive MBS information via a unicast DRB or a multicast DRB, respectively. As used in the present disclosure, unless otherwise specifically noted, the term DRB may refer to a unicast DRB or a multicast DRB.

[0024] Figure 1AAn example wireless communication system 100 is depicted in which the MBS operation techniques of the present disclosure may be implemented. The wireless communication system 100 includes UEs 102A, UEs 102B, UEs 103A, UEs 103B, and base stations 104, 106 of a radio access network (RAN) (e.g., RAN 105) connected to a core network (CN) 110. For ease of reading, unless otherwise specified, UE 102 is used herein to represent UE 102A, UE 102B, or both UE 102A and UE 102B. Similarly, unless otherwise specified, UE 103 is used herein to represent UE 103A, UE 103B, or both UE 103A and UE 103B. For example, base stations 104, 106 may be any suitable type or types of base stations, such as an evolved Node B (eNB), a next generation eNB (ng-eNB), a 5G Node B (gNB), or a 6G base station. As a more specific example, base station 104 may be an eNB or a gNB, and base station 106 may be a gNB.

[0025] Base station 104 supports cell 124, and base station 106 supports cell 126. Cell 124 partially overlaps with cell 126, so that UE 102 and UE 103 can be within range to communicate with base station 104. UE 102A can be within range to communicate with base station 106 at the same time (or within range to detect or measure signals from two base stations 106). For example, the overlap can enable UE 102 to switch between cells (e.g., from cell 124 to cell 126A or 126B) or between base stations (e.g., from base station 104 to base station 106A or base station 106B) before UE 102 experiences a radio link failure. In addition, the overlap allows UE 102 to operate in dual connectivity (DC) with RAN 105. For example, UE 102 may communicate with base station 104 (operating as a master node (MN)) and base station 106A (operating as a secondary node (SN)) in DC, and after completing the handover to base station 106B, may communicate with base station 106B (operating as a MN). As another example, UE 102 may communicate with base station 104 (operating as a MN) and base station 106A (operating as a SN) in DC, and after completing the SN change, may communicate with base station 104 (operating as a MN) and base station 106B (operating as a SN).

[0026] More specifically, when UE 102 is in DC with base station 104 and base station 106A, base station 104 operates as a master eNB (MeNB), a master ng-eNB (Mng-eNB) or a master gNB (MgNB), and base station 106A operates as a secondary gNB (SgNB) or a secondary ng-eNB (Sng-eNB).

[0027] In non-MBS (i.e., unicast) operation, UE 102 may use radio bearers (e.g., DRBs or SRBs) that terminate at different times at a MN (e.g., base station 104) or a SN (e.g., base station 106). For example, after a handover to base station 106B or a SN change, UE 102 may use radio bearers (e.g., DRBs or SRBs) that terminate at different times at base station 106B. UE 102 may apply one or more security keys when communicating on the radio bearers in the uplink (UL) direction (i.e., from UE 102 to the base station) and / or in the downlink (DL) direction (i.e., from the base station to UE 102). In non-MBS operation, UE 102 sends data to a base station via a radio bearer on an uplink BWP of a cell (i.e., within an uplink BWP of a cell), and / or receives data from a base station via a radio bearer on a DL BWP of a cell. The UL BWP may be an initial UL BWP or a dedicated UL BWP, and the DL BWP may be an initial DL BWP or a dedicated DL BWP. The UE 102 may receive paging, system information, a public warning message, or a random access response on the DL BWP. In such non-MBS operation, the UE 102 may be in a connected state. Alternatively, if the UE 102 supports small data transmission in an idle or inactive state, the UE 102 may be in an idle or inactive state.

[0028] In MBS operation, UE 102 may use radio bearers (e.g., DRBs or MRBs) that terminate at different times at a MN (e.g., base station 104) or a SN (e.g., base station 106A). For example, after a handover to base station 106B or a SN change, UE 102 may use radio bearers (e.g., DRBs or MRBs) that terminate at different times at base station 106B, which may be a MN or a SN. The base station may utilize the radio bearers to send application-level messages such as security keys to UE 102. In some implementations, the base station (e.g., MN or SN) may send MBS data to UE 102 over dedicated radio resources (i.e., radio resources dedicated to UE 102) (e.g., via DRBs or MRBs). In these implementations, the base station may apply one or more security keys to protect the integrity of the MBS data and / or encrypt the MBS data and send the encrypted and / or integrity-protected MBS data to UE 102 over dedicated radio resources. Correspondingly, when receiving MBS data on a radio bearer in the downlink direction (from the base station to the UE 102), the UE 102 may apply one or more security keys to decrypt the MBS data and / or check the integrity of the MBS data. In other implementations, the base station (e.g., MN or SN) may send the MBS data from the base station to the UE 102 through a common radio resource (i.e., a radio resource shared by the UE 102 and other UEs such as a common frequency resource (CFR)) or a DL BWP of a cell (e.g., via a DRB or MRB). The DL BWP may be an initial DLBWP, a dedicated DL BWP, or an MBSDL BWP (i.e., a DL BWP specifically used for MBS or not used for unicast). In these implementations, the base station may avoid applying security keys to the MBS data and send the MBS data on the radio bearer. Correspondingly, the UE 102 may omit applying security keys to the MBS data received on the radio bearer. UE 102 may apply the application-level security key received from CN 110 or the MBS server to the MBS data received on the radio bearer.

[0029] Base station 104 includes processing hardware 130, which may include one or more general purpose processors (e.g., central processing units (CPUs)) and computer readable memory storing machine readable instructions executable on the one or more general purpose processors, and / or special purpose processing units. Figure 1AThe processing hardware 130 in the example implementation of includes a base station MBS controller 132 configured to manage or control the transmission of MBS information received from the CN 110 or edge server. For example, the base station MBS controller 132 may be configured to support radio resource control (RRC) configurations, procedures, and messaging associated with MBS procedures, and / or support necessary operations (e.g., MBS activation notification or multicast paging), as discussed below. The processing hardware 130 may include a base station non-MBS controller 134 configured to manage or control one or more RRC configurations and / or RRC procedures when the base station 104 operates as a MN or SN during non-MBS operation.

[0030] Base station 106 includes processing hardware 140, which may include one or more general purpose processors (eg, CPUs) and computer readable memory storing machine readable instructions executable on the general purpose processors, and / or special purpose processing units. Figure 1A The processing hardware 140 in an example implementation of includes a base station MBS controller 142 configured to manage or control the transmission of MBS information received from the CN 110 or an edge server. For example, the base station MBS controller 142 can be configured to support RRC configurations, procedures, and messaging associated with MBS procedures, and / or support necessary operations (e.g., MBS activation notifications), as discussed below. The processing hardware 140 may include a base station non-MBS controller 144 configured to manage or control one or more RRC configurations and / or RRC procedures when the base station 106 operates as a MN or SN during non-MBS operations.

[0031] UE 102 includes processing hardware 150, which may include one or more general-purpose processors (eg, CPUs) and computer-readable memory storing machine-readable instructions executable on the general-purpose processors, and / or special-purpose processing units. Figure 1A The processing hardware 150 in an example implementation of includes a UE MBS controller 152 configured to manage or control the reception of MBS information. For example, the UE MBS controller 152 may be configured to support RRC configurations, procedures, and messaging associated with MBS procedures, and / or support necessary operations (e.g., MBS activation notifications), as discussed below. The processing hardware 150 may include a UE non-MBS controller 154 configured to manage or control one or more RRC configurations and / or RRC procedures according to any of the implementations discussed below when the UE 102 communicates with the MN and / or SN during non-MBS operation.

[0032] CN 110 may be an evolved packet core (EPC) 111 or a fifth generation core (5GC) 160, both of which are Figure 1A . The base station 104 may be an eNB supporting an S1 interface for communicating with the EPC 111, an ng-eNB supporting an NG interface for communicating with the 5GC 160, or a gNB supporting an NR radio interface and an NG interface for communicating with the 5GC 160. The base station 106A may be an EUTRA-NR DC (EN-DC) gNB (en-gNB) with an S1 interface to the EPC 111, an en-gNB not connected to the EPC 111, a gNB supporting an NR radio interface and an NG interface to the 5GC 160, or an ng-eNB supporting an EUTRA radio interface and an NG interface to the 5GC 160. In order to exchange messages directly with each other during the scenarios discussed below, the base stations 104, 106A, and 106B may support an X2 or Xn interface.

[0033] Among other components, the EPC 111 may include a serving gateway (SGW) 112, a mobility management entity (MME) 114, and a packet data network gateway (PGW) 116. The SGW 112 is generally configured to deliver user plane packets related to audio calls, video calls, Internet traffic, etc., and the MME 114 is configured to manage authentication, registration, paging, and other related functions. The PGW 116 provides connectivity from the UE to one or more external packet data networks (e.g., an Internet network and / or an Internet Protocol (IP) Multimedia Subsystem (IMS) network). The 5GC 160 includes a user plane function (UPF) 162 and an access and mobility management (AMF) 164, and / or a session management function (SMF) 166. The UPF 162 is generally configured to deliver user plane packets related to audio calls, video calls, Internet traffic, etc., the AMF 164 is configured to manage authentication, registration, paging, and other related functions, and the SMF 166 is configured to manage PDU sessions.

[0034] UPF 162, AMF 164 and / or SMF 166 may be configured to support MBS. For example, SMF 166 may be configured to manage or control MBS transmission, configure UPF 162 and / or RAN 105 for MBS flow, and / or manage or configure MBS session or PDU session of MBS for UE 102. UPF 162 is configured to deliver MBS data packets of audio, video, Internet traffic, etc. to RAN 105. UPF 162 and / or SMF 166 may be configured for both unicast service and MBS, or only for MBS. In the case where SMF 166 is dedicated to MBS, SMF 166 is a multicast and / or broadcast MB-SMF. In the case where UPF 162 is dedicated to MBS, UPF 162 is a multicast and / or broadcast MB-UPF.

[0035] In general, the wireless communication network 100 may include any suitable number of base stations supporting NR cells and / or EUTRA cells. More specifically, the EPC 111 or the 5GC 160 may be connected to any suitable number of base stations supporting NR cells and / or EUTRA cells. For example, although the examples below specifically refer to specific CN types (EPC, 5GC) and RAT types (5GNR and EUTRA), in general, the technology of the present disclosure may also be applicable to other suitable radio access technologies and / or core network technologies, such as the sixth generation (6G) radio access and / or 6G core network or 5G NR-6G DC.

[0036] In different configurations or scenarios of the wireless communication system 100, the base station 104 may operate as a MeNB, a Mng-eNB, or a MgNB, and the base station 106 may operate as a MeNB, a Mng-eNB, a MgNB, a SgNB, or a Sng-eNB. The UE 102 may communicate with the base station 104 and the base station 106 via the same radio access technology (RAT) (such as EUTRA or NR) or via different RATs.

[0037] When the base station 104 is a MeNB and the base station 106 is an SgNB, the UE 102 may be in EN-DC with the MeNB 104 and the SgNB 106. When the base station 104 is a Mng-eNB and the base station 106 is an SgNB, the UE 102 may be in Next Generation (NG) EUTRA-NR DC (NGEN-DC) with the Mng-eNB 104 and the SgNB 106. When the base station 104 is a MgNB and the base station 106 is an SgNB, the UE 102 may be in NR-NR DC (NR-DC) with the MgNB 104 and the SgNB 106. When the base station 104 is a MgNB and the base station 106A is an Sng-eNB, the UE 102 may be in NR-EUTRA DC (NE-DC) with the MgNB 104 and the Sng-eNB 106.

[0038] Continue to refer Figure 1A , CN 110 communicatively connects UE 102 to MBS network 170 via RAN 105. MBS network 170 can provide UE 102 with multicast and / or broadcast services (MBS) to UE, which can be useful in many content delivery applications such as transparent IPv4 / IPv6 multicast delivery, IPTV, wireless software delivery, group communication, IoT applications, V2X applications, and emergency messages related to public safety. To this end, an entity (e.g., a server or server group) operating in MBS network 170 supports packet exchange with UE. Packets can transmit signaling (such as Session Initiation Protocol (SIP) messages, IP messages, or other suitable messages) and data ("or media"), such as text messages, audio and / or video.

[0039] Figure 1B An example distributed implementation of any one or more of the base stations 104, 106 is depicted. In this implementation, the base station 104 or 106 includes a central unit (CU) 172 and one or more distributed units (DUs) 174. The CU 172 includes processing hardware, such as one or more general-purpose processors (e.g., CPUs) and computer-readable memory storing machine-readable instructions executable on the general-purpose processors, and / or special-purpose processing units. For example, the CU 172 may include Figure 1A processing hardware 130 or 140.

[0040] Each of the DUs 174 also includes processing hardware, which may include one or more general-purpose processors (e.g., CPUs) and computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and / or a dedicated processing unit. For example, the processing hardware may include: a media access control (MAC) controller configured to manage or control one or more MAC operations or procedures (e.g., random access procedures); and a radio link control (RLC) controller configured to manage or control one or more RLC operations or procedures when a base station (e.g., base station 106A) operates as a MN or SN. The processing hardware may also include a physical layer controller configured to manage or control one or more physical layer operations or procedures.

[0041] In some implementations, CU 172 may include a logical node CU-CP 172A that hosts a control plane portion of a Packet Data Convergence Protocol (PDCP) protocol of CU 172 and / or a Radio Resource Control (RRC) protocol of CU 172. CU 172 may also include a logical node CU-UP 172B that hosts a user plane portion of a PDCP protocol and / or a Service Data Adaptation Protocol (SDAP) protocol of CU 172. CU-CP 172A may transmit non-MBS control information and MBS control information, and CU-UP 172B may transmit non-MBS data packets and MBS data packets, as described herein.

[0042] CU-CP 172A may be connected to multiple CU-UPs 172B via an E1 interface. CU-CP 172A selects an appropriate CU-UP 172B for the requested service of UE 102. In some implementations, a single CU-UP 172B may be connected to multiple CU-CPs 172A via an E1 interface. CU-CP 172A may be connected to one or more DUs 174 via an F1-C interface. CU-UP 172B may be connected to one or more DUs 174 via an F1-U interface under the control of the same CU-CP 172A. In some implementations, one DU 174 may be connected to multiple CU-UPs 172B under the control of the same CU-CP 172A. In these implementations, the connection between CU-UP 172B and DU 174 is established by CU-CP 172A using a bearer context management function.

[0043] Figure 2A An example protocol stack 200 is shown in a simplified manner according to which a UE 102 or 103 may communicate with an eNB / ng-eNB or gNB (e.g., one or more of base stations 104 and 106).

[0044] In the example stack 200, the physical layer (PHY) 202A of EUTRA provides transport channels to the EUTRA MAC sublayer 204A, which in turn provides logical channels to the EUTRA RLC sublayer 206A. The EUTRA RLC sublayer 206A in turn provides RLC channels to the EUTRA PDCP sublayer 208 and, in some cases, to the NR PDCP sublayer 210. Similarly, the NRRPHY 202B provides transport channels to the NR MAC sublayer 204B, which in turn provides logical channels to the NR RLC sublayer 206B. The NR RLC sublayer 206B in turn provides RLC channels to the NR PDCP sublayer 210. In some implementations, the UE 102 supports both the EUTRA and NR stacks as shown in FIG. 2 to support handover between EUTRA and NR base stations and / or to support DC over the EUTRA and NR interfaces. Further, as shown in Figure 2, the UE 102 can support the layering of NRPDCP 210 on the EUTRA RLC 206A, and the layering of SDAP sublayer 212 on the NR PDCP sublayer 210.

[0045] The EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 receive packets that may be referred to as service data units (SDUs) (e.g., from an Internet Protocol (IP) layer layered directly or indirectly on the PDCP layer 208 or 210), and output packets that may be referred to as protocol data units (PDUs) (e.g., to the RLC layer 206A or 206B). Except for cases where the difference between SDUs and PDUs is relevant, for simplicity, the present disclosure refers to both SDUs and PDUs as "packets." The packets may be MBS packets or non-MBS packets. For example, the MBS packets include MBS data packets that include application content for an MBS service (e.g., IPv4 / IPv6 multicast delivery, IPTV, wireless software delivery, group communication, IoT applications, V2X applications, and / or emergency messages related to public safety). In another example, the MBS packets include application control information for the MBS service.

[0046] For example, on the control plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 may provide SRBs to exchange RRC messages or non-access stratum (NAS) messages. NAS messages may include mobility management (MM) messages and session management (SM) messages. On the user plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 may provide DRBs to support data exchange. The data exchanged on the NR PDCP sublayer 210 may be SDAP PDUs, Internet Protocol (IP) packets, or Ethernet packets.

[0047] In a scenario where the UE 102 operates in EN-DC with the base station 104 operating as a MeNB and the base station 106 operating as an SgNB, the wireless communication system 100 can provide the UE 102 with a bearer terminated at the MN using the EUTRA PDCP sublayer 208, or a bearer terminated at the MN using the NR PDCP sublayer 210. In various scenarios, the wireless communication system 100 can also provide the UE 102 with a bearer terminated at the SN, which bearer terminated at the SN uses only the NR PDCP sublayer 210. The bearer terminated at the MN can be an MCG bearer, a split bearer, or an SCG bearer terminated at the MN. The bearer terminated at the SN can be an SCG bearer, a split bearer, or an MCG bearer terminated at the SN. The bearer terminated at the MN can be an SRB (e.g., SRB1 or SRB2) or a DRB. The bearer terminated at the SN can be an SRB or a DRB.

[0048] In some implementations, a base station (e.g., base station 104 or 106) broadcasts MBS data packets via one or more MBS radio bearers (MRBs), and then UE 102 receives the MBS data packets via the MRBs. The base station may include the configuration of the MRBs in the multicast configuration parameters (which may also be referred to as MBS configuration parameters) described below. In some implementations, the base station broadcasts the MBS data packets via the RLC sublayer 206, the MAC sublayer 204, and the PHY sublayer 202, and correspondingly, the UE 102 receives the MBS data packets using the PHY sublayer 202, the MAC sublayer 204, and the RLC sublayer 206. In these implementations, the base station and the UE 102 may not use the PDCP sublayer 208 and the SDAP sublayer 212 to communicate the MBS data packets. In other implementations, the base station sends the MBS data packets via the PDCP sublayer 208, the RLC sublayer 206, the MAC sublayer 204, and the PHY sublayer 202, and correspondingly, the UE 102 receives the MBS data packets using the PHY sublayer 202, the MAC sublayer 204, the RLC sublayer 206, and the PDCP sublayer 208. In these implementations, the base station and the UE 102 may not communicate the MBS data packets using the SDAP sublayer 212. In still other implementations, the base station sends the MBS data packets via the SDAP sublayer 212, the PDCP sublayer 208, the RLC sublayer 206, the MAC sublayer 204, and the PHY sublayer 202, and correspondingly, the UE 102 receives the MBS data packets using the PHY sublayer 202, the MAC sublayer 204, the RLC sublayer 206, the PDCP sublayer 208, and the SDAP sublayer 212.

[0049] Figure 2B An example protocol stack 250 is shown in a simplified manner and is similar to the example stack 200 except that the protocol stack 250 includes an RRC sublayer 213 , an MM sublayer 214 , and an SM sublayer 216 .

[0050] In example stack 250, similar to example stack 200, a UE (e.g., UE 102 or 103) communicates with a gNB (e.g., base station 104 or 106). The UE and gNB communicate RRC messages to each other via RRC sublayer 213. The UE communicates with an AMF (e.g., AMF 164) via gNB and MM sublayer 214, and communicates with an SMF (e.g., SMF 166) via gNB, AMF, and SM sublayer 216. The UE and AMF communicate MM messages, and the UE and SMF communicate SM messages.

[0051] The RRC sublayer 214 provides RRC procedures performed by the UE and the gNB. The RRC procedures include procedures for RRC connection establishment, security activation, RRC reconfiguration (e.g., setting, modification and / or release of SRBs and DRBs, and / or configuration and / or reconfiguration of PHY, MAC and RLC configuration parameters), measurement configuration and reporting, and / or RRC connection release. The RRC sublayer 213 also provides transport services to the MM sublayer 214. Therefore, each MM message is carried in an RRC message communicated between the UE and the gNB. The MM sublayer 214 provides MM procedures performed by the UE and the AMF. The MM procedures include registration, tracking area update, UE authentication, and control integrity protection and encryption, temporary identity allocation and / or UE capability reporting. The SM sublayer 216 provides SM procedures performed by the UE and the SMF. The SM procedures include procedures for PDU session establishment, PDU session modification, PDU session release, MBS session join and / or MBS session leave. The MM sublayer 214 also provides transport services to the SM sublayer 216. Therefore, each SM message is carried in an MM message communicated between the UE and the AMF.

[0052] There are two modes defined in the MM sublayer 214: MM-IDLE mode and MM-CONNECTED mode. The MM-IDLE mode defines a state when the UE does not have a signaling connection (i.e., NAS signaling connection) with the AMF, and the MM-CONNECTED mode defines a state when the UE has a signaling connection with the AMF. In some implementations, if the UE operates in the MM-CONNECTED mode in the MM sublayer 214 and operates in the RRC_INACTIVE state, the UE operates in MM-CONNECTED with RRC inactivity indication in the MM sublayer 214. In some implementations, if the UE operates in the MM-CONNECTED mode in the MM sublayer 214 and operates in the RRC_CONNECTED state, the UE operates in the MM-CONNECTED mode in the MM sublayer 214 (i.e., the UE operates in the MM-CONNECTED mode without RRC inactivity indication). In the following description, MM-CONNECTED means an MM-CONNECTED mode without RRC inactivity indication or an MM-CONNECTED mode in an RRC_CONNECTED state.

[0053] In some implementations, the MM sublayer 214 and the SM sublayer 216 are 5GMM sublayer and 5GSM sublayer, respectively. In some implementations, the MM-IDLE mode and the MM-CONNECTED mode are 5GMM-IDLE mode and 5GMM-CONNECTED mode, respectively. In some implementations, MM-IDLE (e.g., 5GMM-IDLE) and MM-CONNECTED (e.g., 5GMM-CONNECTED) are equivalent to connection management (CM)-IDLE and CM-CONNECTED, respectively.

[0054] To simplify the following description, unless explicitly described otherwise, UE 102 refers to UE 102A and UE 102B, and UE 103 refers to UE 103A and UE 103B.

[0055] Figure 3 and Figure 4 is a message passing diagram of an example scenario in which one or more UEs, RANs, CNs, and MBS networks implement the techniques of the present disclosure for managing MBS transmission and reception. In general, Figure 3 and Figure 4 Similar events in the drawings are labeled with similar reference numbers, with differences discussed below where appropriate. Except for the differences shown in the drawings and discussed below, any of the alternative implementations discussed with respect to a particular event (e.g., for message delivery and processing) may be applied to events labeled with similar reference numbers in other drawings.

[0056] First reference Figure 3 , the base station 104 in the example scenario 300 includes a central unit (CU) 172 and a distributed unit (DU) 174. The UE 102 initially operates 302 in an MM-CONNECTED mode and an RRC_CONNECTED state. The UE 102 in the RRC_CONNECTED state communicates 304 control signals and PDUs with the base station 104 using a plurality of configuration parameters. The UE 102 in the MM-CONNECTED mode communicates 304 data (e.g., NAS messages and / or user plane data) with the CN 110 via the base station 104. In some implementations, the PDUs may include RRC PDUs, PDCP PDUs, and / or SDAP PDUs. In other implementations, the PDUs may include NAS messages and / or user plane data.

[0057] In some implementations, the configuration parameters include configuration parameters related to the operation of the RRC and / or PDCP protocol layers (e.g., RRC 214 and / or NRPDCP 210), which the UE 102 and CU 172 use to communicate with each other. In some implementations, the configuration parameters include configuration parameters in the RadoBearerConfig information element (IE) and / or the MeasConfig IE defined in 3GPP specification 38.331.

[0058] In some implementations, the configuration parameters include configuration parameters related to the operation of the RRC, RLC, MAC, and / or PHY protocol layers (e.g., RLC 206B, MAC 204B, and / or PHY 202B), which are used by the UE 102 and the DU 174 to communicate with each other when the UE 102. In some implementations, the configuration parameters include configuration parameters in the CellGroupConfig IE defined in 3GPP specification 38.331.

[0059] In some implementations, UE 102 operates in MM-IDLE mode before event 302, and UE 102 performs NAS procedures with CN 110 via base station 104 to establish a NAS signaling connection with CN 110 (e.g., AMF 164). After successfully establishing the NAS signaling connection, UE 102 transitions from MM-IDLE mode to MM-CONNECTED mode.

[0060] When the UE 102 is communicating with the base station 104, the CU 172 may determine to transition the UE 102 from the connected state to the inactive state based on, for example, data inactivity of the UE 102 (i.e., the UE 102 in the connected state does not have data activity with the base station 104). In some implementations, the CU 172 implements a control plane entity CU-CP (e.g., CU-CP 172A) and a user plane entity CU-UP (e.g., CU-UP 172B), and the CU-CP makes a determination to transition the UE 102 to the inactive state. In some implementations, the CU 172 (or CU-CP) may determine that the UE 102 is in data inactivity based on UE assistance information received from the UE 102, and / or an inactivity notification received from the DU 174 and / or an inactivity notification received from the CP-UP. After a certain period of data inactivity, CU 172 may determine that CU 172 or UE 102 has not sent any data in the downlink direction or uplink direction, respectively, during the certain period. In response to this determination, CU 172 may determine to transition UE 102 to an inactive state.

[0061] In response to determining to transition UE 102 to an inactive state, CU 172 may generate an RRC release message (e.g., an RRCRelease message or an RRCConnectionRelease message) to transition UE 102 to an RRC_INACTIVE state. In some implementations, CU 172 includes a SuspendConfigIE for indicating that UE 102 transitions to an RRC_INACTIVE state. In some implementations, CU 172 generates a PDCP PDU including an RRC release message. Then, CU 172 sends 308 a CU-to-DU message (e.g., a UE context release command message, a UE context modification request message, or a DL RRC messaging message) including an RRC release message or a PDCP PDU to DU 174. Subsequently, DU 174 sends 310 an RRC release message to UE 102. In some implementations, DU 174 generates a MAC PDU including an RRC release message. The RRC release message instructs UE 102 to transition to an inactive state.

[0062] After receiving the RRC release message, the UE 102 transitions 314 from the RRC_CONNECTED state to the RRC_INACTIVE state, and transitions 314 from the MM-CONNECTED mode (i.e., without the RRC inactivity indication) to the MM-CONNECTED mode with the RRC inactivity indication. After transitioning to the RRC_INACTIVE state and the MM-CONNECTED mode with the RRC inactivity indication, the UE 102 camps on the cell (e.g., the cell 124). In the case of a PDCP PDU, the DU 174 generates an RLC PDU including the PDCP PDU, generates a MAC PDU including the RLC PDU, and sends 310 the MAC PDU to the UE 102. In some implementations, the UE 102 may retain the first part or all of the configuration parameters in response to the RRC release message, and the CU 172 also retains the first part or all of the configuration parameters. The UE 102 and the CU 172 may release the second part of the configuration parameters. DU 174 may send a DU-to-CU message (eg, a UE context release complete message or a UE context modification response message) to CU 172 in response to the CU-to-DU message.

[0063] After or in response to transitioning the UE 102 to the RRC_INACTIVE state, the CU 172 sends 312 an RRC Inactive Transition Report message to the CN 110 indicating that the UE 102 entered the RRC_INACTIVE state. The CN 110 determines 316 that the UE 102 is operating in the MM-CONNECTED mode with the RRC Inactive indication. At a later time, the CN 110 may notify the UE of the activation of the MBS session. To notify the UE of the MBS session activation, the CN 110 generates a CN to BS message including an MBS session ID and sends 318 the CN to BS message to the RAN 105. The MBS session ID identifies the MBS session. In some implementations, the CN to BS message of event 318 may be a Next Generation Application Protocol (NGAP) message defined in 3GPP specification 38.413. For example, the NGAP message is a multicast group paging message. In another example, the NGAP message is a multicast activation request message.

[0064] After receiving 318 the CN to BS message, CU 172 extracts the MBS session ID from the CN to BS message, generates a CU to DU message including the MBS session ID, and sends 320 a CU to DU paging message to DU 174. In some implementations, the CU to DU paging message is an F1 Application Protocol (F1AP) multicast group paging message. After receiving 320 the CU to DU paging message, DU 174 generates a paging message (e.g., an RRC paging message) including the MBS session ID. After (e.g., in response to) the CU to DU paging message of event 320, DU 174 sends 322 a paging message in at least one first paging occasion (PO) in at least one first paging frame (PF) on the cell (e.g., via broadcast) to page one or more UEs. In some implementations, DU 174 determines a first PO and a first PF for a UE operating in one of an RRC_IDLE state and an RRC_INACTIVE state.

[0065] In some implementations, DU 174 determines PF and PO according to the following formula:

[0066] The SFN of PF is given by:

[0067] ○(SFN+PF_offset)mod T=(T divN)*(UE_ID modN)

[0068] Index(i_s), indicating that the index of the PO is given by:

[0069] ○i_s=floor(UE_ID / N)modNs,

[0070] Wherein T is a discontinuous reception (DRX) cycle of a UE (eg, UE 102) operating in RRC_IDLE state or RRC_INACTIVE state.

[0071] If extended DRX (eDRX) is not configured for the UE, DU 174 may determine T by the shortest of the UE-specific DRX value (if configured by RRC (e.g., RRC release message) and / or upper layers or provided in PC5-RRC signaling in the case of L2 U2N relay UEs) and the default DRX value broadcasted in system information. In RRC_IDLE state, if UE-specific DRX is not configured by upper layers, DU 174 may apply the default value.

[0072] In the RRC_IDLE state, if the higher layer configures eDRX for the UE, that is, T eDRX,CN :

[0073] -If T eDRX,CN No longer than 1024 radio frames, then T = T eDRX,CN ;

[0074] -otherwise:

[0075] • During a CN configured PTW, the DU 174 may determine T by the shortest of the UE specific DRX value (if configured by upper layers) and the default DRX value broadcasted in the system information.

[0076] In the RRC_INACTIVE state, if eDRX is configured by RRC (e.g., base station 104), that is, T eDRX,RAN , and / or configured by the upper layer, i.e. T eDRX,CN :

[0077] -If T eDRX,CN and T eDRX,RAN If both are no longer than 1024 radio frames, then T = min{T eDRX,RAN ,T eDRX,CN}.

[0078] -If T eDRX,CN No longer than 1024 radio frames and T is not configured eDRX,RAN , then T is determined by the UE-specific DRX value configured by RRC and T eDRX,CN The shortest one among them is used to determine.

[0079] -If T eDRX,CN Longer than 1024 radio frames:

[0080] If T is not configured eDRX,RAN :

[0081] o During a CN configured PTW, T is determined by the shortest of the UE specific DRX value (if configured by RRC and / or upper layers) and the default DRX value broadcasted in system information. Outside a CN configured PTW, T is determined by the UE specific DRX value configured by RRC;

[0082] Otherwise, if T eDRX,RAN No longer than 1024 radio frames:

[0083] During a CN-configured PTW, T is determined by the UE-specific DRX value (if configured by upper layers) and T eDRX,RAN and the shortest of the default DRX values ​​broadcast in the system information. Outside the PTW configured by the CN, T is determined by T eDRX,RAN to be sure.

[0084] N: total number of paging frames in T

[0085] Ns: Number of paging occasions of PF

[0086] PF_offset: offset used for PF determination

[0087] UE ID (e.g., 5G-S-TMSI):

[0088] If the eDRX cycle is configured by RRC or upper layers and eDRX-Allowed is signaled in SIB1 (e.g., broadcasted on a cell (e.g., cell 124)):

[0089] -UE ID mod 4096

[0090] otherwise:

[0091] -UE ID mod 1024

[0092] A PF is a radio frame and may contain one or more POs. A PO may include one or more PDCCH monitoring opportunities and may consist of one or more time periods (e.g., subframes or OFDM symbols) in which DU 174 may send paging DCI. DU 174 may send system information (e.g., via broadcast) to configure UE 102 to monitor one or more PDCCH monitoring opportunities in a PO. For example, the system information may include a search space configuration (e.g., pagingSearchSpace) and / or a PDCCH monitoring configuration (e.g., firstPDCCH-Monit oringOccasionOfPO and nr0fPDCCH-MonitoringOccasionPerSSB-InPO).

[0093] In the above description, the term "upper layer" may refer to the MM sublayer 214 or the CN 110, and "RRC" may refer to the RRC sublayer 213 or the RRC. In some implementations, the DU 174 determines at least one first paging occasion for a UE operating in one of the RRC_IDLE states and a UE operating in the RRC_INACTIVE state.

[0094] DU 174 may determine the first PO and the first PF using the first UE identification index value (i.e., "UE ID" in the above formula), the first paging DRX cycle value (i.e., "T" in the above formula), and the formula described above. In some implementations, CU 172 may include a first UE identification list for paging in the CU-to-DU paging message. The first UE identification list for paging may include one or more items. In some implementations, CU 172 may include the first UE identification index value and the first paging DRX value in the first item of the one or more items. In some implementations, CU 172 receives the first UE paging list from CN 110, for example, in a CN-to-BS message of event 318, and the first UE paging list includes the first UE identification index value and the first paging DRX cycle value. In other implementations, CU 172 determines the first UE identification index value based on the first UE ID of UE 102A. For example, CU 172 sets the first UE identification index value to the first UE ID. In another example, CU 172 uses a formula to derive a first UE identification index value, wherein the first UE ID is used as an input to the formula. In one implementation, CU 172 receives the first UEID from UE 102A in an RRC message (e.g., an RRCSetupComplete message). In another implementation, CU 172 receives a CN to BS message (e.g., an NGAP message or a UE information transfer message) including the first UE ID from CN 110, instead of the CN to BS message of event 318. In one implementation, CU 172 receives a CN to BS message including a first paging DRX cycle value from CN 110, instead of the CN to BS message of event 318. For example, the CN to BS message is an NGAP message such as an initial context setup request message, a UE context modification request message, a handover request message, or a path switch request confirmation message. In one implementation, the first paging DRX cycle value is a UE-specific DRX cycle value of UE 102A received by CU 172 from CN 110. In another implementation, the first paging DRX cycle value is a default paging DRX cycle value used or configured by the base station 104 to page the UE.

[0095] In other implementations, CU 172 receives a BS-to-BS message including a first UE ID and / or a first paging DRX cycle value from another base station (i.e., a second base station such as base station 106). For example, the BS-to-BS message is an Xn Application Protocol (XnAP) message such as a handover request message or a retrieve UE context response message. In one implementation, the first paging DRX cycle value is a UE-specific DRX cycle value of UE 102A received by the second base station from CN 110. In another implementation, the first paging DRX cycle value is a default paging DRX cycle value used or configured by the second base station (e.g., base station 106) for paging UEs. In yet another implementation, the first paging DRX cycle value is a RAN paging cycle value used or configured by the second base station (e.g., base station 106) for UE 102A.

[0096] In yet other implementations, CU 172 determines a first paging DRX cycle value and includes the first paging DRX cycle value in the RRC release message at event 308. In these implementations, the first paging DRX cycle value is a RAN paging cycle value. In yet other implementations, CU 172 determines the first paging DRX cycle value as the minimum of a default paging DRX cycle value, a RAN paging cycle value, and / or a UE-specific DRX cycle value.

[0097] In some alternative implementations, instead of the CU 172, the DU 174 receives the first UE identification index value and / or the first paging DRX cycle value from an operations, administration, and maintenance (OAM) node.

[0098] In some implementations, DU 174 preconfigures (e.g., prestores or predetermines) one or more UE identification index values ​​and / or one or more paging DRX cycle values. DU 174 uses the preconfigured UE identification index value, the preconfigured DRX cycle value, and the formula described above to determine the first PO and the first PF. In some implementations, DU 174 does this because the CU-to-DU paging message of event 320 does not include a / the (first) UE identification list for paging, or DU 174 does not support a / the (first) UE identification list for paging. In these cases, CU 172 does not include a / the UE (first) identification list for paging in the CU-to-DU paging message of event 320 because the CN-to-BS message of event 318 does not include a / the (first) UE paging list, or CU 172 does not support a / the (first) UE identification list or a / the (first) UE paging list for paging. In one implementation, the preconfigured DRX cycle value includes a minimum value among a default paging DRX cycle value, a RAN paging cycle value, and / or a UE-specific DRX cycle value. In another implementation, the preconfigured DRX cycle value includes a default paging DRX cycle value, a RAN paging cycle value, and / or a UE-specific DRX cycle value.

[0099] In addition to the at least one first PO, in some implementations, the DU 174 may send 324 a paging message in at least one second PO in at least one second PF on the cell to page one or more UEs. In some implementations, the DU 174 determines the second PO and the second PF for a UE operating in the other of the RRC_IDLE state and the RRC_INACTIVE state.

[0100] In some implementations, DU 174 uses the second identification index value (i.e., "UE ID" in the above formula), the second paging DRX cycle value (i.e., "T" in the above formula), and the formula described above to determine the second PO and the second PF. In some implementations, CU 172 may include the second UE identification index value and the second paging DRX cycle value in the second item of one or more items in the first UE identification list for paging. Alternatively, CU 172 may send 321 a CU-to-DU paging message including the second UE identification list for paging. The second UE identification list for paging includes one or more items, and one of the one or more items includes the second UE identification index value and the second paging DRX cycle value. In some implementations, the first UE paging list includes the second UE identification index value and the second paging DRX cycle value. In other implementations, CU 172 determines the second UE identification index value based on the first UE ID. For example, CU 172 sets the second UE identification index value to the first UE ID. In another example, CU 172 uses a formula to derive a first UE identification index value, wherein the first UE ID is used as an input to the formula. In yet other implementations, CU 172 receives 319 a CN to BS message including a second UE paging list from CN 110, and the second UE paging list includes a second UE identification index value and a second paging DRX cycle value. The CN to BS message of event 319 may be an NGAP message defined in 3GPP specification 38.413. For example, the NGAP message is a multicast group paging message. In yet other implementations, CU 172 receives a CN to BS message including a second paging DRX cycle value from CN 110, rather than a CN to BS message of event 319. For example, the CN to BS message is an NGAP message such as an initial context setup request message, a UE context modification request message, a handover request message, or a path switch request confirmation message. In one implementation, the second paging DRX cycle value is a UE-specific DRX cycle value of UE 102A received by CU 172 from CN 110. In another implementation, the second paging DRX cycle value is a default paging DRX cycle value used or configured by the base station 104 to page the UE.

[0101] In other implementations, the BS-to-BS message includes the first UE ID and / or the second paging DRX cycle value. In one implementation, the second paging DRX cycle value is a UE-specific DRX cycle value of UE 102A received by the second base station from CN 110. In another implementation, the second paging DRX cycle value is a default paging DRX cycle value used or configured by the second base station (e.g., base station 106) for paging UEs.

[0102] In some implementations, the second PF partially or completely overlaps with the first PF. In other implementations, the second PF does not overlap with the first PF. In some implementations, the second PO partially overlaps with the first PO. In other implementations, the second PO does not overlap with the first PO.

[0103] In some implementations, the first PF is included in multiple instances of a paging DRX cycle having a length set by a first paging DRX cycle value or a preconfigured paging DRX cycle value. Each of the multiple instances includes a specific PF in the first PF. The multiple instances may be consecutive. At event 322, DU 174 sends a paging message in a first PO in a first PF in multiple instances of a paging DRX cycle. In other implementations, the first PF is included in multiple paging DRX cycles having a length set by a preconfigured paging DRX cycle value. Each of the multiple paging DRX cycles has a different DRX cycle length. In other words, at event 322, DU 174 sends a paging message in a first PO in a first PF in multiple paging DRX cycles. In yet other implementations, the first PF is included in multiple instances of multiple paging DRX cycles having a length set by a preconfigured paging DRX cycle value. Each of the multiple paging DRX cycles has a different length. In other words, at event 322, the DU 174 sends a paging message in a first PO in a first PF in a plurality of instances of the plurality of paging DRX cycles. For each of the plurality of paging DRX cycles, the plurality of instances may be consecutive.

[0104] In some implementations, DU 174 may send a paging message on a paging control channel (PCCH) in a first PO and / or a second PO. In some implementations, DU 174 may generate a DCI and a CRC of the DCI to send a paging message on the PDCCH at each PDCCH monitoring opportunity in each first PO in the first PO and / or each second PO in the second PO. The DCI used for the transmission of the paging message in the PDCCH monitoring opportunity may be the same or different. DU 174 scrambles the CRC using a paging radio network temporary identifier (P-RNTI). DU 174 may include a downlink assignment in the DCI indicating the radio resources used for the transmission of the paging message. DU 174 may transmit the DCI and the scrambled CRC to UE 102 on the PDCCH and send the paging message on the indicated radio resources.

[0105] When the UE 102 receives the DCI and the scrambled CRC on the PDCCH in a PDCCH opportunity in one of the first POs or one of the second POs, the UE 102 verifies the scrambled CRC using the P-RNTI. If the UE 102 verifies that the scrambled CRC is valid, the UE 102 receives or attempts to receive a paging message on the radio resource 322 or 324 according to the DCI. After receiving the paging message 322 or 324 or in response thereto, the UE 102 may perform 328 an RRC connection recovery procedure to activate (e.g., initiate) reception of the MBS session identified by the MBS session ID. In some implementations, the UE 102 may perform 326 a random access procedure with the DU 174 to perform the RRC connection recovery procedure.

[0106] In some implementations, the UE 102 sends an RRC recovery request message (e.g., an RRCResumeRequest message) to the CU 172 via the DU 174 to perform the RRC connection recovery procedure. In the case where the random access procedure is a four-step random access procedure, the UE 102 sends a message 3 including an RRC recovery request message to the DU 174, which in turn sends the RRC recovery request message to the CU 172. In the case where the random access procedure is a two-step random access procedure, the UE 102 sends a message A including an RRC recovery request message to the DU 174, which in turn sends the RRC recovery request message to the CU 172. In response to the RRC recovery request message, the CU 172 sends an RRC recovery message (e.g., an RRCResume message) to the UE 102 via the DU 174. In response to the RRC resume message, the UE 102 transitions 330 to an RRC_CONNECTED state and an MM-CONNECTED state (i.e., without an RRC inactivity indication), and sends an RRC resume complete message (e.g., an RRCResumeComplete message) to the CU 172 via the DU 174. After or in response to transitioning the UE 102 to the RRC_CONNECTED state, the CU 172 sends 332 an RRC Inactivity Transition Report message to the CN 110, which indicates that the UE 102 entered the RRC_CONNECTED state. The CN 110 determines 334 that the UE 102 is operating in the MM-CONNECTED mode (i.e., without an RRC inactivity indication).

[0107] After CN 110 determines at event 334 that UE 102 is operating in MM-CONNECTED mode (i.e., without RRC inactivity indication), CN 110 sends 336 MBS data packets to CU 172 (or CU-UP of CU 172). CU 172 then sends 338 the MBS data packets to DU 174. DU 174 sends 340 the MBS data packets to UE 102 via multicast. In some implementations, CU 172 generates PDCP PDUs that each include a specific MBS data packet in the MBS data packets and sends the PDCP PDUs to DU 174 at event 338. DU 174 generates MAC PDUs that include the PDCP PDUs and sends the MAC PDUs to UE 102 at event 340. Each of the MAC PDUs may include a specific PDCP PDU in the PDCP PDUs or a portion of the PDCP PDUs.

[0108] In some implementations, DU 174 generates a multicast configuration to configure MBS data reception on cell 124, and sends a DU to CU message (e.g., a UE context modification required message, a UE context modification response message, or a UE context setup response message) including the multicast configuration to CU 172. In one implementation, CU 172 includes the multicast configuration and / or the MRB configuration for configuring the MRB in the RRC recovery message. In another implementation, at event 304, CU 172 sends an RRC reconfiguration message including the multicast configuration and / or the MRB configuration to UE 102. After (i.e., in response to) receiving the RRC release message at event 310 and while UE 102 is operating 314 in the RRC_INACTIVE state, UE 102 retains the multicast configuration. At event 340 , the DU 174 transmits MBS data packets (eg, MAC PDUs or PDCP PDUs) according to the multicast configuration, and the UE 102 receives the MBS data packets from the DU 174 according to the multicast configuration and the MRB configuration.

[0109] Events 302, 304, 308, 310, 312, 314, 316, 326, 328, 332, 330, 334 are UE-specific. That is, these events occur for each of UE 102A and UE 102B.

[0110] Next go to Figure 4In scenario 400, UE 102 initially operates 414 in RRC_INACTIVE state and MM-CONNECTED mode with RRC inactivity indication, and UE 103 initially operates 415 in RRC_IDLE and MM-IDLE mode. Similar to event 314, UE 102 operates in 414 in RRC_INACTIVE state and MM-CONNECTED mode with RRC inactivity indication. Correspondingly, similar to event 316, CN 110 determines 416 that UE 102 operates in MM-CONNECTED mode with RRC inactivity indication. Correspondingly, CN 110 determines 417 that UE 103 operates in MM-IDLE mode.

[0111] Similar to event 318, CN 110 sends 418 a CN to BS message including the MBS session to CU 172 to notify the UE of the activation of the MBS session identified by the MBS session. Similar to event 320, after receiving the CN to BS message of event 418 (e.g., in response thereto), CU 172 sends 420 a CU to DU message to DU 174. Similar to event 322, DU 174 may send 422 a paging message in at least one first PO in at least one first PF on a cell (e.g., cell 124). Similar to event 324, DU 174 may send 424 a paging message in at least one second PO in at least one second PF on a cell.

[0112] Similar to event 328, after or in response to receiving 422 or 424 the paging message, UE 102 may perform 428 an RRC connection recovery procedure to activate (e.g., initiate) reception of the MBS session identified by the MBS session ID. In some implementations, similar to event 326, UE 102 may perform 426 a random access procedure with DU 174 to perform an RRC connection recovery procedure.

[0113] After or in response to receiving 422 or 424 the paging message, UE 103 performs 427 an RRC connection establishment procedure with CU 172 via DU 174. In some implementations, similar to event 326, UE 103 may perform 425 a random access procedure with DU 174 to perform an RRC connection establishment procedure. In response to the RRC connection establishment procedure, UE 103 transitions 431 to RRC_CONNECTED state and MM-CONNECTED mode (i.e., no RRC inactivity indication).

[0114] In order to perform the RRC connection establishment procedure, UE 103 sends an RRC setup request message (e.g., RRCSetupRequest message) to CU 172 via DU 174. In the case where the random access procedure is a two-step random access procedure, UE 103 sends the RRC setup request message to DU 174 in message A of the two-step random access procedure. In the case where the random access procedure is a four-step random access procedure, UE 103 sends the RRC setup request message in message 3 of the four-step random access procedure. Subsequently, DU 174 sends the RRC setup request message to CU 174. In response to the RRC setup request message, CU 172 sends an RRC setup message (e.g., RRCSetup message) to UE 103 via DU 174. In response, UE 103 transitions 431 to the RRC_CONNECTED state and sends an RRC setup completion message (e.g., RRCSetupComplete message) to CU 172 via DU 174.

[0115] In some implementations, the UE 103 configures a first SRB (e.g., SRB1) to communicate RRC messages with the CU 172 (via the DU 174) in response to the RRC setup message. In these implementations, the UE 103 sends an RRC setup complete message to the CU 172 via the first SRB and the DU 174. After transitioning 431 to the RRC_CONNECTED state, the UE 103 may send a service request message to the CN 110 via the DU 174 and the CU 172 to establish a NAS signaling connection. In one implementation, the UE 103 may include the service request message in the RRC setup complete message. The CU 172 retrieves the service request message from the RRC setup complete message and sends 429 a BS to CN message (e.g., an initial UE message message) including the service request message to the CN 110. After successfully sending the service request message, the UE 103 transitions 431 from the MM-IDLE mode to the MM-CONNECTED mode. After receiving the BS-to-CN message at event 429, CN 110 determines 442 that UE 103 is operating in MM-CONNECTED mode.

[0116] After performing the RRC connection establishment process with the UE 103, the CU 172 may perform a 433 security activation process (e.g., an RRC security mode process) with the UE 103 via the DU 174 to activate security (e.g., integrity protection / integrity check and / or encryption / decryption) regarding communication with the UE 102. In detail, the CU 172 may send a security activation command message (e.g., a SecurityModeCommand message) to the UE 103, for example, via the first SRB and the DU 174, to perform the 433 security activation process. In response, the UE 103 activates security (e.g., integrity protection and / or encryption) regarding communication with the CU 172, and sends a security activation completion message (e.g., a SecurityModeComplete message) to the CU 172, for example, via the first SRB and the DU 174. After activating security, CU 172 may perform 435 at least one RRC reconfiguration procedure with UE 102 via DU 174 to configure a second SRB (e.g., SRB2), DRB, and / or MRB to exchange RRC messages, unicast data, and / or multicast data with UE 103, respectively. In some implementations, CU 172 may perform 435 at least one RRC reconfiguration procedure with UE 102 via DU 174 to configure a second SRB (e.g., SRB2), DRB, and / or MRB to exchange RRC messages, unicast data, and / or multicast data with UE 103, respectively. Figure 3 The multicast configuration is received from DU 174, the multicast configuration and the MRB configuration for configuring the MRB are included in the RRC reconfiguration message in the RRC reconfiguration process, and the RRC reconfiguration message is sent to UE 103. In some implementations, CU 172 sends the multicast configuration and / or the MRB configuration to UE 102 in the RRC recovery message of the RRC connection recovery process. In other implementations, when UE 102 operates in the RRC_CONNECTED state before event 414, CU 172 sends the RRC reconfiguration message including the multicast configuration and / or the MRB configuration to UE 102.

[0117] After UE 102 and 103 transition to MM-CONNECTED mode, CN 110 sends 436 MBS data packets to CU 172 (or CU-UP of CU 172). CU 172 then sends 438 MBS data packets to DU 174. DU 174 sends 440 MBS data packets to UE 102 and UE 103 via multicast. Events 436, 438, and 440 are similar to events 336, 338, and 340. UE 102 and 103 receive 440 MBS data packets according to the multicast configuration and the MRB configuration.

[0118] Figures 5 to 9C is a flow chart depicting an example method that a CN node (e.g., CN 110 or AMF 164) may implement to page a UE for an MBS session. Fig.10and Fig.11 is a flow chart depicting an example method that a RAN node (eg, base station 104, CU 172, or CU-CP 172A) may implement to page a UE for an MBS session. Figures 12 to 13B is a flow chart depicting an example method that a RAN node (eg, base station 104 or DU 174) may implement to page a UE for an MBS session. Fig.14 and Fig.15 is a flow chart depicting an example method that a UE may implement to receive paging for an MBS session.

[0119] Figure 5 5 is a flow chart of an example method 500 for paging a UE for an MBS session. At block 502, a first CN node receives a request message for an MBS session from a second CN node. In some implementations, the request message includes an MBS session ID. In one implementation, the MBS session ID may be a temporary mobile group identifier (TMGI). In some implementations, the first CN node is an AMF (e.g., AMF 164), and the second CN node is an SMF (SMF 166) or an MB-SMF (e.g., MB-SMF166). In some implementations, the request message is a Namf_MT_EnableGroupReachability request message. In other implementations, the request message is a Namf_MBSCommunication_N2MessageTransfer request message.

[0120] At box 504, the first CN node notifies at least one RAN node to page at least one first UE and at least one second UE for the MBS session in response to receiving the request message, wherein the at least one UE operates in MM-CONNECTED in RRC inactive state and the at least one second UE operates in MM-IDLE state (e.g., events 38, 418).

[0121] Figure 66 is a flow chart of an example method 600 for paging a UE for an MBS session. At block 602, a CN node communicates with at least one first UE operating in an MM-CONNECTED mode without an RRC inactivity indication. At block 604, the CN node receives at least one first BS-to-CN message, each of which indicates that a specific UE of the at least one first UE enters an RRC_INACTIVE state (e.g., event 312). At block 606, it is determined based on the at least one first BS-to-CN message that the at least one first UE is operating in MM-CONNECTED with an RRC inactivity indication (e.g., events 316, 416). At block 608, the CN node determines or maintains at least one second UE operating in an MM-IDLE mode (e.g., event 417). At box 610, the CN node sends a CN to BS message to one or more RAN nodes to page at least one first UE and at least one second UE for an MBS session, wherein the at least one UE operates in MM-CONNECTED mode in an RRC inactive state and the at least one second UE operates in MM-IDLE mode (e.g., events 318, 418).

[0122] Figure 7 is a flow chart of an example method 700 for paging a UE for an MBS session. At box 702, a first CN node receives a request message for an MBS session from a second CN node. At box 704, the first CN node notifies at least one RAN node in response to the request message to page multiple UEs regardless of the protocol mode of the UEs (e.g., events 318, 418). In some implementations, when the first CN node determines to page multiple UEs for an MBS session, the first CN node does not check the protocol status of any UE. In some implementations, the protocol mode (or state) includes an MM-CONNECTED mode in an RRC inactive state, and an MM-IDLE mode. In some implementations, the protocol mode may further include an MM-CONNECTED mode (i.e., no RRC inactivity indication). For Figure 5 The examples and implementations described can be applied to Figure 7 .

[0123] FIG. 8A to FIG. 8B The same boxes in the drawings are marked with the same reference numerals.

[0124] Fig. 8AIt is a flowchart of an example method 800A for paging a UE for an MBS session. At block 802, the CN node sends a first CN-to-BS message to one or more RAN nodes to page UEs 1, …, N, where N > 1 (e.g., events 318, 319, 418, 419). At block 804, in response to sending or determining to send the first CN-to-BS message, the CN node starts paging timers 1, …, N for UEs 1, …, N respectively. At block 806, the CN node maintains the paging timers 1, …, N running until receiving paging response messages from UEs 1, …, N respectively or until the paging timers 1, …, N expire respectively.

[0125] In some implementations, the paging timer is an instance of timer T3513. In other implementations, the paging timer is an instance of a new timer defined in 3GPP specification 24.501 or in a 3GPP specification for 6G. In some implementations, the CN node receives a paging response message from UE M among UEs 1, …, N via one of the one or more RAN nodes, where 0 < M < N + 1. The CN node stops the paging timer M in response to the paging response message. If the CN node does not receive paging response messages from UEs 1, …, M - 1, M + 1, …, N, the CN node maintains the other paging timers 1, …, M - 1, M + 1, …, N running.

[0126] In some implementations, the CN node includes a first UE paging list in the first CN-to-BS message. In one implementation, the CN may include UE identification index values 1, …, N indicating UE IDs 1, …, N of UEs 1, …, N respectively in the first UE paging list. In another implementation, the CN node includes paging DRX cycle configurations 1, …, N for UEs 1, …, N respectively in the first UE paging list. Each of the one or more RAN nodes may determine paging occasions based on the UE identification index values 1, …, N and / or the paging DRX cycle configurations 1, …, N and send paging messages at the paging occasions.

[0127] In other implementations, the CN node does not include a UE paging list in the first CN-to-BS message. In these implementations, each of the one or more RAN nodes sends paging messages at paging occasions in one or more paging cycles determined by each RAN node.

[0128] If one, some or all of the paging timers 1, ..., N expire, the CN node may send a second CN to BS message to one or more RAN nodes to request the one or more RAN nodes to page some of the UEs 1, ..., N that have not yet been connected to the CN node. In some implementations, the CN node includes a second UE paging list in the second CN to BS message. In one implementation, the CN may include a UE identification index value in the second UE paging list, the UE identification index value indicating the UE ID of the UE with which the expired paging timer is associated. The CN node may include a paging DRX cycle value of the UE with which the expired paging timer is associated in the second UE paging list. Therefore, each of the one or more RAN nodes may determine a paging occasion based on the UE identification index value and / or the paging DRX cycle value, and send a paging message at the paging occasion, such as for Figure 3 The paging message may include an MBS session ID of the MBS session. In some implementations, the paging messages are the same paging messages. In other implementations, some of the paging messages include one or more UE IDs, and some of the paging messages do not include a UE ID.

[0129] In other implementations, the CN node does not include the UE paging list in the second CN to BS message. In these implementations, each of the one or more RAN nodes sends a paging message on a paging occasion in one or more paging cycles determined by each RAN node, such as for Figure 3 The paging message may include an MBS session ID of the MBS session. In other implementations, some of the paging messages include one or more UE IDs, and some of the paging messages do not include a UE ID.

[0130] Figure 8B 800B is a flow chart of an example method 800B, which is similar to the method 800A, except that the method 800B includes blocks 805 and 807 instead of blocks 804 and 806. At block 805, in response to sending the first CN to BS message, the CN node starts a single paging timer for UE 1, ..., N, respectively. At block 807, the CN node maintains the paging timer running until all paging response messages from UE 1, ..., N are received or the paging timer expires.

[0131] In some implementations, if the paging timer expires, the CN node may send a second CN to BS message to one or more RAN nodes requesting the one or more RAN nodes to page some of the UEs 1, ..., N that are not yet connected to the CN node, such as for Fig. 8A described.

[0132] 9A to 9C The same boxes in the drawings are marked with the same reference numerals.

[0133] Fig.9A 900A is a flow chart of an example method for paging a UE for an MBS session. At block 902, a CN node determines to send or sends a CN to BS message for paging to a RAN node (e.g., events 318, 418). At block 904, the CN node determines whether the CN to BS message is for unicast paging or for multicast paging. If the CN node determines that the CN to BS message (e.g., a first instance of the CN to BS message) is for unicast paging, the process proceeds to block 906A. At block 906A, the CN node starts a (single) paging timer in response to sending or determining to send the CN to BS message. Otherwise, if the CN node determines that the CN to BS message (e.g., a second instance of the CN to BS message) is for multicast paging, the process proceeds to block 908A. At block 908A, the CN node avoids starting a paging timer.

[0134] In some implementations, if the CN node receives a NAS message from the UE in response to paging, the CN node stops the paging timer. If the paging timer expires, the CN node may send a CN to BS message to the RAN node or another RAN node to page the UE.

[0135] Fig. 9B 900A, except that method 900B includes blocks 906B and 908B instead of blocks 906A and 908A. If the CN node determines that the CN to BS message (e.g., the first instance of the CN to BS message) is for unicast paging, the flow proceeds to block 906B. At block 906B, similar to block 906A, the CN node starts the first paging timer. Otherwise, if the CN node determines that the CN to BS message (e.g., the second instance of the CN to BS message) is for multicast paging, the flow proceeds to block 908B. At block 908B, similar to block 906A, the CN node starts the first paging timer. Figure 8B In block 805, the CN node starts a second paging timer. In some implementations, the first paging timer may be timer T3513, and the second paging timer is a timer other than timer T3513. For example, the second paging timer is a new timer defined in 3GPP specification 24.501. Figure 8B and Fig.9A The examples and implementations described can be applied to Fig. 9B .

[0136] In some implementations, the CN node starts a first paging timer and a second paging timer having the same timer value. In other implementations, the CN node starts a first paging timer and a second paging timer having a first timer value and a second timer value, respectively. In some implementations, the first timer value and the second timer value are different. In one implementation, the first timer value is smaller than the second timer value because the MBS session may take or allow longer time to wait for multiple UEs to respond to multicast paging.

[0137] Fig. 9C 900A and 900B, except that method 900C includes blocks 906C and 908C instead of blocks 906A-B and 908A-B. If the CN node determines that the CN to BS message (e.g., the first instance of the CN to BS message) is for unicast paging, the flow proceeds to block 906C. At block 906C, similar to block 906A, the CN node starts a paging timer with a first timer value. Otherwise, if the CN node determines that the CN to BS message (e.g., the second instance of the CN to BS message) is for multicast paging, the flow proceeds to block 908C. At block 908C, similar to block 906A, the CN node starts a paging timer with a first timer value. Otherwise, if the CN node determines that the CN to BS message (e.g., the second instance of the CN to BS message) is for multicast paging, the flow proceeds to block 908C. Fig.9A At block 906A, the CN node starts a paging timer with a second timer value. In some implementations, the paging timer is timer T3513 defined in 3GPP specification 24.501.

[0138] In some implementations, the first timer value and the second timer value are different. In one implementation, the first timer value is smaller than the second timer value because the MBS session may take or tolerate longer time to wait for multiple UEs to respond to the multicast paging.

[0139] Fig.101 is a flow chart of an example method 1000 for paging a UE for an MBS session. At block 1002, a RAN node receives a CN to BS message for an MBS session from a CN node (e.g., events 318, 418). In some implementations, the RAN node is a base station (e.g., base station 104) or a CU (e.g., CU 172 or CU-CP 172A), and the CN node is an AMF (e.g., AMF 164). At block 1004, the RAN node pages at least one first UE and at least one second UE for the MBS session in response to the CN to BS message, wherein at least one UE operates in an inactive state and at least one second UE operates in an idle state (e.g., events 320, 322, 321, 324, 420, 422, 421, 424). In some implementations, the inactive state and the idle state are an RRC_INACTIVE state and an RRC_IDLE state, respectively.

[0140] Fig.11 1 is a flow chart of an example method 1100 for paging a UE for an MBS session. At block 1102, a RAN node receives a CN to BS message for an MBS session from a CN node (e.g., events 318, 418). In some implementations, the RAN node is a base station (e.g., base station 104) or a CU (e.g., CU 172 or CU-CP 172A), and the CN node is an AMF (e.g., AMF 164). At block 1104, the RAN node pages multiple UEs in response to the CN to BS message regardless of the protocol state of the UE (e.g., events 320, 322, 321, 324, 420, 422, 421, 424). In some implementations, the protocol state includes an RRC_INACTIVE state and an RRC_IDLE state. In one implementation, the protocol state may further include an RRC_CONNECTED state.

[0141] Fig.121 is a flow chart of an example method 1200 for paging a UE for an MBS session. At block 1202, a RAN node receives an interface message including an MBS session ID (e.g., events 318, 320, 319, 321, 418, 420, 419, 421). At block 1204, the RAN node determines, in response to the interface message, at least one first paging occasion and at least one first paging frame for paging a UE operating in an inactive state and at least one second paging occasion and at least one second paging frame for paging a UE operating in an idle state. At block 1206, the RAN node sends a first paging message in at least one first paging occasion and at least one first paging frame (e.g., events 318, 320, 322, 418, 420, 422). At block 1208, the RAN node sends a second paging message in at least one second paging occasion and at least one second paging frame (e.g., events 321, 324, 421, 424).

[0142] against Figure 3 and Figure 4 The examples and implementations described can be applied to Fig.12 .

[0143] FIG. 13A to FIG. 14 Like boxes in B are marked with like reference numerals.

[0144] Fig.13A 1300A is a flow chart of an example method 1300A for paging a UE for an MBS session. At block 1302, a RAN node receives an interface message (e.g., events 318, 320, 319, 321, 418, 420, 419, 421) including an MBS session ID. At block 1304, the RAN node determines whether the interface message includes a paging list. If the RAN node determines that the interface message (e.g., a first instance of the interface message) includes a paging list, the flow proceeds to block 1306. At block 1306, the RAN node determines one or more paging occasions and one or more paging frames based on information in the paging list. Otherwise, if the RAN node determines that the interface message (e.g., a second instance of the interface message) does not include a paging list, the flow proceeds to block 1308. At block 1308, the RAN node determines one or more paging occasions and one or more paging frames based on preconfigured information. The flow proceeds from blocks 1306 and 1308 to block 1310. At block 1310, the RAN node sends one or more paging messages in one or more paging occasions and one or more paging frames (eg, events 322, 324, 422, 424).

[0145] In some implementations, at block 1306, the RAN node determines one or more instances of the one or more paging DRX cycles based on information in the UE paging list, and at block 1310, the RAN node sends one or more paging messages in one or more paging occasions and one or more paging frames in the one or more instances of the one or more paging DRX cycles. In some implementations, at block 1308, the RAN node determines one or more instances of the one or more paging DRX cycles based on preconfigured information, and at block 1310, the RAN node sends one or more paging messages in one or more paging occasions and one or more paging frames in the one or more instances of the one or more paging DRX cycles.

[0146] In some implementations, the information in the paging list includes one or more items, each of which includes a UE identification index value and / or a paging DRX cycle value. If one of the one or more items does not include a paging DRX cycle value, the RAN node may use a preconfigured paging DRX cycle value. In some implementations, the preconfigured information includes a preconfigured UE identification index value and a preconfigured paging DRX cycle value.

[0147] In some implementations, in the case where the interface message is a CN to BS message (e.g., events 318, 319, 418, 419), the paging list is a UE paging list. In some implementations, in the case where the interface message is a CN to DU message (e.g., events 320, 321, 420, 421), the paging list is a UE identity list for paging.

[0148] Fig. 13B is a flow chart of an example method 1300B, which is similar to method 1300A, except that method 1300B includes blocks 1301 and 1305 instead of blocks 1302 and 1304.

[0149] At block 1301, the RAN node receives an interface message including an MBS session ID and a paging list (e.g., events 318, 320, 319, 321, 418, 420, 419, 421). At block 1305, the RAN node determines that the RAN node supports the paging list. If the RAN node determines that the RAN node supports the paging list, the flow proceeds to block 1306. Otherwise, if the RAN node determines that the RAN node does not support the paging list, the flow proceeds to block 1308.

[0150] Fig. 13C is a flow chart of an example method 1300C, which is similar to methods 1300A and 1300B, except that method 1300C includes block 1303 instead of block 1305.

[0151] At block 1303, the RAN node ignores or discards the paging list. That is, at block 1308, regardless of whether the received interface message for paging the UE for the MBS session includes a paging list, the RAN node determines one or more paging occasions and one or more paging frames according to preconfigured information.

[0152] Fig.14 14 is a flow chart of an example method 1400 for receiving paging for an MBS session. At block 1402, the MM sublayer of the UE (e.g., the MM sublayer 214) receives a paging indication and a TMGI, for example, from a lower layer of the UE (e.g., an RRC sublayer, such as the RRC sublayer 213). At block 1404, the MM sublayer determines whether the UE is in an MM-CONNECTED mode with an RRC inactivity indication. If the MM sublayer determines that the UE is in an MM-CONNECTED mode with an RRC inactivity indication, the flow proceeds to block 1406. At block 1406, the MM sublayer requests initiation of an RRC connection recovery procedure (e.g., events 328, 428). In some implementations, the MM sublayer requests the lower layer to initiate the RRC connection recovery procedure. Otherwise, if the MM sublayer determines that the UE is in an MM-IDLE mode, the flow proceeds to block 1408. In block 1408, the MM sublayer requests initiation of an RRC connection establishment procedure (e.g., event 427). In some implementations, the MM sublayer requests the lower layer to initiate the RRC connection establishment procedure.

[0153] In some implementations, the lower layer may send a single message including a paging indication and a TMGI to the MM sublayer. In some implementations, the "TMGI" may be replaced with an "MBS session ID". In some implementations, the MM sublayer determines to remain in MM-CONNECTED mode with an RRC inactivity indication in response to receiving the paging indication and the TMGI. In some implementations, when the MM sublayer is in MM-CONNECTED mode with an RRC inactivity indication, the MM sublayer determines that the paging indication with the TMGI is a RAN paging. After (e.g., in response to) completing the RRC connection recovery procedure (e.g., receiving an RRC recovery message or sending an RRC recovery complete message), the lower layer sends a first lower layer indication to the MM sublayer. The MM sublayer transitions to MM-CONNECTED mode (i.e., without an RRC inactivity indication) in response to the first lower layer indication. In some implementations, the MM sublayer determines to remain in MM-IDLE mode in response to receiving the paging indication and the TMGI. In some implementations, when the MM sublayer is in MM-IDLE mode, the MM sublayer determines that the paging indication with the TMGI is a CN paging or an AMF paging. After completing the RRC connection establishment procedure (e.g., receiving an RRC setup message or sending an RRC setup complete message) or sending a NAS message (e.g., a ServiceRequest message) (e.g., in response thereto), the lower layer sends a second lower layer indication to the MM sublayer. The MM sublayer transitions to the MM-CONNECTED mode (i.e., without an RRC inactivity indication) in response to the second lower layer indication.

[0154] Fig.15 1 is a flow chart of an example method 1500 for receiving paging for an MBS session. At block 1502, the UE receives a paging message including a TMGI, for example, from a RAN node (e.g., DU 174 or base station 104) (e.g., events 322, 324, 422, 424). At block 1504, the UE determines whether the UE is in an RRC_INACTIVE state. If the UE determines that the UE is in an RRC_INACTIVE state, the flow proceeds to block 1506. At block 1506, the RRC sublayer initiates an RRC connection recovery procedure (e.g., events 328, 428). Otherwise, if the UE determines that the UE is in an RRC_IDLE state, the flow proceeds to blocks 1508 (optional) and 1510. At block 1508, the RRC sublayer of the UE (e.g., RRC sublayer 213) sends the TMGI to the MM sublayer of the UE. At block 1510, the UE initiates an RRC connection establishment procedure (e.g., event 427).

[0155] In some implementations, the RRC sublayer of the UE performs the actions described in blocks 1502, 1504, 1506, and 1510. In some implementations, the RRC sublayer sends a TMGI to the MM sublayer to indicate paging for the TMGI, i.e., Fig.14 The paging indication with TMGI.

[0156] The following additional considerations apply to the foregoing discussion.

[0157] In general, the description of one of the above figures may apply to another of the above figures. If there is no conflict, the examples, implementations, and methods described above may be combined. The events or boxes described above may be optional or may be omitted. For example, the events or boxes with dashed lines in the figures may be optional. In some implementations, "message" is used and "information element (IE)" can be used to replace "message", and vice versa. In some implementations, "IE" is used and "field" can be used to replace "IE", and vice versa. In some implementations, "configuration" can be replaced with "configurations" or "configuration parameters", and vice versa. In some implementations, "MBS" can be replaced with "MBS session", or vice versa. In some implementations, "MBS session ID" can be replaced with "MBS session ID" or "TMGI", and "MBS session" can be replaced with "multiple MBS sessions". "MM" can be replaced with "5GMM".

[0158] The user device (e.g., UE 102) in which the technology of the present disclosure can be implemented can be any suitable device capable of wireless communication, such as a smart phone, a tablet computer, a laptop computer, a mobile game console, a point of sale (POS) terminal, a health monitoring device, a drone, a camera, a media streaming dongle or another personal media device, a wearable device such as a smart watch, a wireless hotspot, a femtocell or a broadband router. Further, in some cases, the user device can be embedded in an electronic system, such as a head unit (head unit) or an advanced driver assistance system (ADAS) of a vehicle. Further, the user device can be operated as an Internet of Things (IoT) device or a mobile Internet device (MID). Depending on the type, the user device may include one or more general-purpose processors, a computer-readable memory, a user interface, one or more network interfaces, one or more sensors, etc.

[0159] Certain embodiments are described in the present disclosure as including logic or multiple components or modules. A module may be a software module (e.g., code stored on a non-transitory machine-readable medium) or a hardware module. A hardware module is a tangible unit that is capable of performing certain operations and may be configured or arranged in a particular manner. A hardware module may include a dedicated circuit system or logic that is permanently configured to perform certain operations (e.g., configured as a dedicated processor, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC)). A hardware module may also include programmable logic or circuit systems that are temporarily configured by software to perform certain operations (e.g., as contained within a general-purpose processor or other programmable processor). The decision to implement a hardware module with a dedicated and permanently configured circuit system or with a temporarily configured circuit system (e.g., configured by software) may be driven by cost and time considerations.

[0160] When implemented in software, the techniques may be provided as part of an operating system, as a library used by multiple applications, as a specific software application, etc. The software may be executed by one or more general-purpose processors or one or more special-purpose processors.

Claims

1. A paging method implemented in a node of a radio access network RAN, the method comprising: receiving a message comprising an identifier of a multicast and / or broadcast service MBS session; as well as In response to determining that the message includes a paging list, a user equipment UE is paged using information in the message.

2. The method of claim 1, wherein: the message including the paging list is a first message received in a first instance; The method further comprises, in a second example: receiving a second message; In response to determining that the second message does not include a paging list, paging the UE using preconfigured information.

3. The method of claim 2, wherein: The paging of the UE using the preconfigured information includes using a preconfigured paging cycle.

4. The method according to claim 2 or 3, wherein: The paging of the UE using the preconfigured information includes using a preconfigured identity index UEID value.

5. A method as claimed in any one of the preceding claims, wherein: The paging of the UE using the information in the message includes indexing a UE ID value using a UE identity included in the paging list.

6. The method of claim 5, wherein the paging of the UE using the information in the message comprises: Determine a paging frame PF for the paging using the UE ID value; as well as A paging message is sent in the PF.

7. The method of claim 6, wherein the paging of the UE using the information in the message comprises: Determine a paging occasion PO for the paging using the UE ID value; as well as The paging message is sent in the PO.

8. The method of claim 7, further comprising: System information including an indication of the PO is broadcast in the cell in which the UE operates, and the PO includes one or more physical downlink control channel (PDCCH) opportunities.

9. The method of any preceding claim, wherein the paging of the UE using the information in the message comprises: The discontinuous reception (DRX) cycle included in the paging list is used.

10. A method as claimed in any preceding claim, wherein the message is a multicast group paging message.

11. The method of claim 10, wherein: The node of the RAN is a distributed unit DU of a distributed base station, and The message is received from a central unit CU of the distributed base station.

12. A method as claimed in any preceding claim, wherein the paging of the UE comprises using a Temporary Mobile Group Identity (TMGI).

13. The method of any one of claims 1 to 5, further comprising: determining a first PO for paging one or more UEs operating in an idle state of a radio resource control, RRC, protocol; as well as A second PO is determined for paging one or more UEs operating in an inactive state of the RRC protocol.

14. The method of claim 13, further comprising: determining a first PF associated with the first PO; and A second PF associated with the second PO is determined.

15. A radio access network RAN ​​node, comprising: Transceiver; as well as Processing hardware configured to implement a method as claimed in any one of the preceding claims.

Images