Method executed by user equipment, and user equipment

Abstract

The present disclosure provides a method executed by a user equipment (UE), and a UE. The method executed by a UE comprises: step 1, the UE receiving a paging message from a base station; step 2, if condition A and condition B are satisfied, executing at least one of operation 1 to operation 3, wherein the condition A is that the UE is in RRC_INACTIVE and has joined one or more MBS sessions indicated by a TMGI comprised in the paging message; and the condition B is that the paging message does not comprise a PagingRecordList field, or none of ue-Identities of all PagingRecord fields comprised in the paging message matches a UE identifier allocated by an upper layer or a full I-RNTI stored by the UE, or the UE has initiated an RRC connection resume procedure in which resumeCause is set to mt-SDT.

Description

Methods executed by user equipment and user equipment Technical Field

[0001] This invention relates to the field of wireless communication technology, and more specifically, to a method performed by a user equipment and a user equipment. Background Technology

[0002] A research project SI (see SP-190625) concerning improvements to the 5G multicast and broadcast service architecture has been approved. One of the goals of this SI (referred to as Goal A) is to support general MBS services in 5GS. Use cases that can benefit from this feature include (but are not limited to) public safety, V2X applications, transparent IPv4 / IPv6 multicast transport, IPTV, wireless software transport, group communication, and IoT applications. Correspondingly, at the 3rd Generation Partnership Project (3GPP) RAN#86 plenary meeting, a work project on NR Multicast and Broadcast Services (NR MBS) (see non-patent literature: RP-193248: New WID: NR Multicast and Broadcast Service) was proposed and approved. This work project aims to provide support for Goal A in the RAN. The goals of this work project have been largely achieved, and specific descriptions of the relevant solutions can be found in 3GPP Release 17 technical documents, such as TS38.300-h30, TS38.331-h30, and TS38.321-h30. At the 3GPP RAN#94 plenary meeting, a work project entitled Enhanced NR Multicast and Broadcast Services was approved (see non-patent literature: RP-213568: New WID: Enhancements of NR Multicast and Broadcast Services). This work project aims to further enhance MBS broadcast and multicast in version 17, one of its goals being to support user equipment receiving MBS multicast services / sessions in RRC inactive state.

[0003] This invention discusses issues related to RAN supporting user equipment to receive MBS multicast services / sessions in the RRC inactive state. Summary of the Invention

[0004] To address the aforementioned problems, the present invention provides a method executed by a user equipment and a user equipment thereof.

[0005] According to a first aspect of the present invention, a method performed by a user equipment (UE) is provided, comprising: a first step, wherein the UE receives a paging message from a base station; and a second step, wherein if conditions A and B are satisfied, at least one of operations 1 and 2 is performed: operation 1: if conditions C and D are satisfied, an RRC connection recovery process is initiated. operation 2: if condition D is satisfied, it is further determined whether condition C is satisfied; if condition C is satisfied, an RRC connection recovery process is initiated; operation 3: if condition D is not satisfied, at least one of operations 3-1 to 3-3 is performed: operation 3-1: detection of G-RNTI(s) corresponding to the TMGI(s) is started; operation 3-2: if the UE is notified to stop detecting G-RNTIs of all multicast sessions joined and configured to be received as RRC_INACTIVE, further, if there is no multicast MCCH, and if (1) the cell selected or reselected by the UE is different In the cell where the UE receives multicast services during RRC_CONNECTED, or (2) the UE is not configured to receive any multicast services during RRC_CONNECTED, and if condition C is met, then the RRC connection recovery process is initiated for multicast reception; Operation 3-3: If not met: the UE is notified to stop detecting G-RNTI(s) of all multicast sessions that have been joined and configured to receive RRC_INACTIVE, further, if met: the UE is notified to stop detecting G-RNTI of at least one multicast session and the PTM configuration of the multicast session is not included in the RRC release. The message then performs the following operations: If the multicast MCCH does not appear and condition C is met, an RRC connection recovery procedure is initiated for multicast reception; wherein, condition A is that the UE is in RRC_INACTIVE and the UE has joined one or more MBS sessions indicated by the TMGI contained in the paging message; condition B is that the paging message does not contain the PagingRecordList field, or the ue-Identity of all PagingRecord fields contained in the paging message does not match the UE identifier assigned by the upper layer or the fullI-RNTI stored by the UE, or the UE has initiated an RRC connection recovery procedure with resumeCause set to mt-SDT; condition C is that the paging message does not contain the mt-SDT indication; condition D is that at least one of the MBS sessions joined by the UE indicated by the TMGI contained in the paging message is not configured for reception in RRC_INACTIVE, or the inactiveReceptionAllowed of at least one of the MBS sessions joined by the UE indicated by the TMGI contained in the paging message is not included in the paging message.

[0006] Furthermore, according to a second aspect of the present invention, a user equipment is provided, comprising: a processor; and a memory storing instructions, wherein the instructions, when executed by the processor, perform the methods described above.

[0007] Invention Effects

[0008] According to the present invention, a method and corresponding user equipment are provided that can prevent the user equipment (UE) from initiating the RRC connection recovery process due to the lack of a valid PTM configuration during an MBS multicast session. Attached Figure Description

[0009] The above and other features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein:

[0010] Figure 1 is a flowchart schematically illustrating a method performed by a user equipment (UE) according to an embodiment of the present invention.

[0011] Figure 2 is a simplified structural block diagram of the user equipment involved in this invention. Detailed Implementation

[0012] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the present invention should not be limited to the specific embodiments described below. Furthermore, for the sake of simplicity, detailed descriptions of well-known technologies not directly related to the present invention have been omitted to prevent confusion in understanding the present invention.

[0013] The following describes some of the terminology involved in this invention. For the specific meanings of these terms, please refer to the latest relevant 3GPP documents, such as TS38.300-i20, TS38.321-i20, TS38.323-i20, and TS38.331-i20. Furthermore, while this embodiment of the invention uses broadcast / multicast services as an example, this embodiment is not limited to broadcast / multicast services and can be applied to other application scenarios.

[0014] UE: User Equipment.

[0015] RRC: Radio Resource Control.

[0016] RRC_CONNECTED: RRC connection state.

[0017] RRC_INACTIVE: RRC inactive state.

[0018] RRC_IDLE: RRC idle state.

[0019] RAN: Radio Access Network.

[0020] NR: New RAT, New Radio Access Technology.

[0021] MBS: Multicast / Broadcast Services. Multicast can also be called groupcast.

[0022] MTCH: MBS Traffic Channel.

[0023] AS: Access Stratum.

[0024] NAS: Non-Access Stratum.

[0025] RB: Radio Bearer. DRB is the data radio bearer, and SRB is the signaling radio bearer.

[0026] MRB: MBS Radio Bearer, which is a radio bearer configured for MBS delivery. MRBs are divided into multicast MRBs and broadcast MRBs. Multicast MRBs are radio bearers configured for MBS multicast transmission, and broadcast MRBs are radio bearers configured for MBS broadcast transmission.

[0027] TMGI: Temporary Mobile Group Identity, used to identify an MBS session. This disclosure describes an embodiment of TMGI used to identify an MBS multicast session.

[0028] RNTI: Radio Network Temporary Identifier.

[0029] PTM: Point to Multipoint, a delivery method for MBS services. In PTM delivery, the base station delivers a single copy of MBS data packets to a set of UEs. UEs use G-RNTI or G-CS-RNTI to receive PTM transmissions. For example, the base station schedules the same G-RNTI-based Group Common Physical Downlink Control Channel (PDCCH) using the same G-RNTI-based Group Common Physical Downlink Shared Channel (PDSCH).

[0030] PTP: Point to Point, a delivery method for MBS services. In PTP delivery, the RAN node delivers multiple copies of MBS data packets individually to each UE. For example, the base station uses a UE-specific PDCCH scrambled with a UE-specific RNTI to schedule a UE-specific PDSCH scrambled with the same UE-specific RNTI.

[0031] G-RNTI: Group RNTI, used to scramble the scheduling and transmission of PTM for one or more MBS multicast services.

[0032] The RRC Resume Request message (RRCResumeRequest or RCResumeRequest1) is used to request the resumption of a suspended RRC connection or to perform a RAN-based notification area RNA update. When a UE initiates an RRC connection resumption request, if the SIB1 received from the camped cell, serving cell, or cell performing the RRC resumption procedure contains a useFullResumeID field, then the UE uses the RCResumeRequest1 message and sets the resumeIdentity field in the RCResumeRequest1 message to the fullI-RNTI stored by the UE; otherwise, it uses RCResumeRequest and sets the resumeIdentity field in the RCResumeRequest message to the stored shortI-RNTI. The RRC Release message (RRCRelease) is used to command the release of an RRC connection or the suspension of an RRC connection. The RRC Reconfiguration message (RRCReconfiguration) is used to command the modification of an RRC connection. The RRCReject message is used to reject the establishment of an RRC connection or the resumption of an RRC connection. The RRC Setup message (RRCSetup) is used to establish an SRB1. SRB1 is used for RRC messages (which may include piggybacked NAS messages) and NAS messages established before SRB2 is established, both using the dedicated control channel DCCH logical channel. The RRC recovery message RRCResume is used to restore a suspended RRC connection. In this disclosure, the useFullResumeID field indicates the recovery identifier and recovery request message used. When this field is included in SIB1, the fullI-RNTI and RRCResumeRequest1 messages are used; when the field is not included in SIB1, the shortI-RNTI and RRCResumeRequest messages are used. The shortI-RNTI uses fewer bits than the I-RNTI-Value (i.e., the fullI-RNTI) to identify the suspended UE context of a UE in an RRC inactive state. The RRC recovery process (i.e., the RRC connection recovery process) is used to restore suspended RRC connections, including restoring SRB(s), DRB(s), and multicast MRB(s), or performing RNA updates, or implementing MBS multicast receive requests, or initiating small data transmission SDT in the RRC_INACTIVE state, etc. During the RRC recovery process, the UE sends an RRC recovery request message to the base station and may receive an RRC recovery message RRCResume, an RRC setup message RRCSetup, an RRC release message RRCRelease, or an RRC rejection message RRCReject from the base station.

[0033] In this invention, the network, base station, and RAN can be used interchangeably. The network can be a Long Term Evolution (LTE) network, an NR network, an enhanced Long Term Evolution (eLTE) network, or other networks defined in subsequent 3GPP evolution versions, such as a 6G network.

[0034] Currently, NR MBS services include MBS broadcast (also known as MBS broadcast session, broadcast MBS, or MBS broadcast service) and MBS multicast (also known as MBS multicast session, multicast MBS, or MBS multicast service). MBS broadcast provides a downlink-only MBS transmission mode for services with low Quality of Service (QoS), allowing UEs in RRC connected, RRC idle, and RRC inactive states to receive the MBS service. The UE obtains the MBS broadcast configuration information broadcast by the network through the MBS control channel MCCH. In 3GPP Release 17, before receiving MBS multicast services (i.e., MBS multicast sessions), the UE needs to establish an RRC connection with the base station. Then, the base station configures the resources for receiving MBS multicast services for the UE through dedicated RRC signaling (also known as RRC messages, such as RRC reconfiguration messages). The MBS radio bearer MRB for receiving these MBS multicast services is also configured by the base station for the UE through dedicated RRC signaling. Only UEs in RRC connected state with configured MRBs can receive the corresponding MBS multicast services.

[0035] Version 17 does not support UEs receiving MBS multicast sessions while in RRC inactive mode. Therefore, before receiving MBS multicast services (i.e., MBS multicast sessions), the UE needs to establish an RRC connection with the base station. Then, the base station (i.e., the network) configures the resources or PTM configuration for the UE to receive MBS multicast services through dedicated RRC signaling (also known as RRC messages, such as RRC reconfiguration messages). The MBS radio bearer MRB for receiving these MBS multicast services is also configured for the UE by the base station through dedicated RRC signaling. Only UEs in RRC connected mode with configured MRB can receive the corresponding MBS multicast services. The base station can send MBS multicast services using either PTM or PTP methods. Sending MBS multicast services using PTM means that the transport block containing MBS multicast session data is addressed using G-RNTI (or the PDCCH scheduling the transport block is addressed using G-RNTI or scrambled), while sending MBS multicast services using PTP means that the transport block containing MBS multicast session data is addressed using C-RNTI (or the PDCCH scheduling the transport block is addressed using C-RNTI or scrambled). Therefore, when an MBS multicast session is activated by the core network or a base station has MBS multicast session data to send, the network supporting MBS multicast notifies UEs in the RRC idle state or RRC inactive state through a group notification mechanism. Upon receiving the group notification, UEs that have joined the MBS multicast session or are interested in the MBS multicast session establish or restore an RRC connection with the network to receive the corresponding MBS multicast session. The group notification uses P-RNTI addressing on the physical downlink control channel (PDCCH) and a UE monitor paging channel. The paging message used for group notifications contains the MBS session identifier TMGI, which is used to page all UEs that have joined the relevant MBS multicast session and are in RRC idle or RRC inactive states. In other words, the base station does not page UEs individually (for the purpose of UEs receiving MBS multicast sessions).

[0036] Version 18 supports UE receiving MBS multicast sessions in RRC inactive state. For MBS multicast sessions configured for RRC inactive state reception, the base station can provide or configure PTM configuration information (also called MBS multicast session configuration information, MBS multicast session PTM configuration, or MBS multicast configuration) for receiving the MBS multicast session to the UE via dedicated RRC signaling (e.g., RRC Release message) or via the multicast MBS control channel MCCH (i.e., multicast MCCH). The information required to obtain the multicast MCCH (or multicast MCCH configuration) can be configured for the UE via dedicated RRC signaling or system information block (denoted as SIB24), i.e., SIB24 contains the information required to obtain the multicast MCCH / MTCH (i.e., MCCH and / or MTCH) configuration for MBS multicast reception in RRC inactive state. The PTM configuration information may include configuration information of the MRB corresponding to the MBS multicast session (e.g., mrb-ListMulticast indicating the list of multicast MRBs to which the relevant MBS multicast session is mapped) and / or fields indicating the index of the PDSCH configuration entry in the pdschConfigList of the MTCH and / or the identifier TMGI of the MBS multicast session and its corresponding G-RNTI / G-CS-RNTI and / or DRX configuration information, etc. The pdschConfigList field contains a list of PDSCH parameters that can be configured according to the G-RNTI; if included in SIB20 or SIB24, only one entry entity is allowed to be configured. For example, the PTM configuration of an MBS multicast session is information related to the reception of the MBS multicast session contained in the MBS MulticastConfiguration message. The MBSMulticastConfiguration message contains the control information applicable for MBS multicast services transmitted via multicast MRBs for RRC_INACTIVE UEs.The MBSMulticastConfiguration message can be transmitted on the multicast MCCH or included in the RRC release message. The multicast MCCH is a PTM downlink channel used to transmit control information of MBS multicast session associated with one or more MTCH(s) from the network to the UE in the RRC_INACTIVE state. For MBS multicast sessions received in the RRC_INACTIVE state, in this embodiment, the MBS multicast session being active or activated means that the MBS multicast session is in progress or about to begin, the UE has started receiving (or is receiving) the MBS multicast session, or the UE has started detecting the G-RNTI corresponding to the MBS multicast session, or the UE has started monitoring the multicast MCCH-RNTI (MBS Control Channel RNTI) of the multicast MCCH. The network can instruct the UE to activate or resume data transmission of the MBS multicast via the multicast MCCH, RRC signaling (e.g., RRC release message), or paging message. For example, including the TMGI of the MBS multicast session in the paging message indicates that the MBS multicast session has been activated or resumed data transmission. The absence of the stopMonitoringRNTI field for the MBS multicast session in the multicast MCCH or RRC release message indicates that the MBS multicast session has been activated or resumed data transmission. The stopMonitoringRNTI field is used to instruct the UE to stop detecting the G-RNTI of the corresponding multicast session. After receiving the indication that the MBS multicast session has been activated or resumed data transmission, the UE begins receiving the MBS multicast session (i.e., the UE begins detecting the G-RNTI corresponding to the MBS multicast session). The activation of MBS multicast in this embodiment also applies to the case of resuming data transmission in the MBS multicast session, which will not be elaborated further below. In this embodiment, the MBS multicast session being inactive or deactivated means that the MBS multicast session has ended or suspended data transmission, or the UE has stopped receiving the MBS multicast session (i.e., the UE stops detecting the G-RNTI corresponding to the MBS multicast session).The network associates a stopMonitoringRNTI field with each MBS multicast session in the multicast MCCH message (i.e., the MBSMulticastConfiguration message transmitted on the multicast MCCH) to explicitly instruct the UE to stop detecting the G-RNTI corresponding to the MBS multicast session (i.e., to instruct the MBS multicast session to be deactivated or to stop data transmission). Upon receiving this instruction, the UE stops receiving the MBS multicast session. The UE stopping receiving the MBS multicast session can mean the UE stops detecting the G-RNTI or G-CS-RNTI corresponding to the MBS multicast session. Therefore, in this disclosure, the instruction to deactivate or stop data transmission of the MBS multicast session is the same as the instruction to instruct the UE to stop detecting the G-RNTI or G-CS-RNTI associated with the MBS multicast session. Furthermore, the instruction to activate or resume data transmission of the MBS multicast session is the same as the instruction to start detecting the G-RNTI corresponding to the MBS multicast session, i.e., the MBS multicast session is not indicated as having stopped detecting G-RNTI. MBS multicast session deactivation includes situations where the MBS multicast session is temporarily without data transmission, and MBS multicast session activation includes situations where the MBS multicast session resumes data transmission. In this disclosure, the multicast session or service is the MBS multicast session or service. The following embodiments use G-RNTI as an example for illustration, and embodiments obtained by replacing G-RNTI with G-CS-RNTI are also within the scope of this disclosure.

[0037] Each MBS multicast session is identified by a TMGI and associated with a G-RNTI or G-CS-RNTI. The UE receives an MBS multicast session by detecting the G-RNTI or G-CS-RNTI associated with that MBS multicast session.

[0038] For a UE configured to receive an MBS multicast session in the RRC_INACTIVE state, when the MBS multicast session is activated or resumes data transmission, if the MBS multicast session is configured and / or allowed to receive data in the RRC_INACTIVE state, and / or the UE has a (valid) PTM configuration with the MBS multicast session, it can directly receive the MBS multicast session without establishing an RRC connection with the base station. The network can configure the PTM configuration information for the MBS multicast session received in the RRC_INACTIVE state for the UE via multicast MCCH and / or proprietary RRC signaling (e.g., RRC release message, RRC reconfiguration message) (e.g., included in the MBSMulticastConfiguration message). The MBS multicast configuration message (MBSMulticastConfiguration) can be transmitted on the multicast MCCH (in which case the MBSMulticastConfiguration message can be called a multicast MCCH message) or included in the RRC release message. If the RRC release message is used to configure the PTM configuration information of the MBS multicast session received by the UE in the RRC_INACTIVE state, the network can include the MBSMulticastConfiguration message in the RRC release message sent to the UE.

[0039] When a UE receives an RRC release message from a base station, if the multicastConfigInactive field is included in the received RRC release message, it indicates that the UE has been configured to receive MBS multicast in RRC_INACTIVE. The multicastConfigInactive field indicates whether the UE is configured to receive multicast sessions in RRC_INACTIVE. The multicastConfigInactive field may contain two fields: the inactivePTM-Config field and the inactiveMCCH-Config field. The inactivePTM-Config field carries an MBSMulticastConfiguration message, used to indicate the multicast sessions that can be received in RRC_INACTIVE, and optionally, the corresponding PTM configuration for the cell where the multicast session was received in RRC_CONNECTED. The inactiveMCCH-Config field carries system information SIB24, which indicates the multicast MCCH / MTCH configuration for MBS multicast reception in RRC_INACTIVE in the serving cell.

[0040] Currently, the instruction for the UE to start detecting the G-RNTI of the MBS multicast session can be implemented by including the TMGI of the MBS multicast session in the paging message (i.e., if the paging message received by the UE contains a TMGI that allows / configures the MBS multicast session to be received in RRC_INACTIVE, it means that the UE has received an instruction to start detecting the G-RNTI of the MBS multicast session). Alternatively, the MBSMulticastConfiguration message can indicate whether to stop detecting the G-RNTI corresponding to the MBS multicast session. Specifically, for an MBS multicast session whose TMGI is included in the MBSMulticastConfiguration message, if the MBSMulticastConfiguration message also contains the stopMonitoringRNTI field for the MBS multicast session, it indicates that the UE has received an indication to stop detecting the MBS multicast session's G-RNTI (i.e., stop detecting the MBS multicast session's G-RNTI). Conversely, if the MBSMulticastConfiguration message does not contain the stopMonitoringRNTI field, it indicates that the UE has not received an indication to stop detecting the MBS multicast session's G-RNTI. The stopMonitoringRNTI field instructs the UE to stop detecting the G-RNTI of the corresponding MBS multicast session. Stopping the detection of the MBS multicast session's G-RNTI is indicated by associating / configuring a stopMonitoringRNTI field with each MBS multicast session. If an MBS multicast session is not associated / configured with a corresponding stopMonitoringRNTI field, it indicates that the MBS multicast session has not been indicated to stop detecting G-RNTI. The MBSMulticastConfiguration message can be transmitted on the multicast MCCH or included in an RRC release message. Specifically, the MBSMulticastConfiguration message can be included in the MulticastConfigInactive field of the suspendConfig field in the RRC release message.The `suspendConfig` field indicates the configuration for the `RRC_INACTIVE` state. If the `RRC` release message received by the UE contains an `MBSMulticastConfiguration` message or a `MulticastConfigInactive` field, the UE is considered to be configured to receive MBS multicast or multicast sessions in `RRC_INACTIVE`. Alternatively, if the `RRC` release message received by the UE (or an `MBSMulticastConfiguration` message contained in the `RRC` release message) contains a `TMGI`, the UE is considered to be configured to receive the MBS multicast indicated by the `TMGI` in `RRC_INACTIVE`. It should be noted that UE obtaining the multicast MCCH refers to the UE obtaining the `MBSMulticastConfiguration` message from the multicast MCCH. For MBS multicast sessions configured for `RRC_INACTIVE` reception, if the `TMGI` of the MBS multicast session is included in a paging message and the paging message also contains the `inactiveReceptionAllowed` field corresponding to the `TMGI`, the UE considers it can receive the MBS multicast session in `RRC_INACTIVE`.

[0041] For a UE configured to receive MBS multicast sessions in RRC inactive mode, when the UE is in RRC inactive mode and receives a paging message from the base station, if the paging message contains an indication of downlink (i.e., for mobile terminated or for the user) small data SDT transmission (denoted as mt-SDT) and meets the conditions for initiating an RRC recovery process for SDT in response to RAN paging, then the RRC connection recovery process is initiated. If the resumeCause field carried in the RRC recovery request message sent by the UE during the RRC connection recovery process is set to mt-SDT, the UE may not be switched to RRC_CONNECTED. If the MBS multicast sessions that the UE has joined, as indicated by the TMGI in the paging message, are all configured for RRC_INACTIVE reception and the paging message contains the inactiveReceptionAllowed field of the TMGI, the RRC connection recovery process is initiated because the UE has already initiated an RRC connection recovery process for mt-SDT. During SDT, the UE is still in the RRC inactive state. At this time, how the UE should handle MBS multicast sessions that are included in the paging message and have been joined and configured to receive in the RRC inactive state, and whose paging message contains the inactiveReceptionAllowed field of the TMGI, is a problem that needs to be solved.

[0042] Furthermore, if the TMGI indicated in the paging message indicates that all MBS multicast sessions the UE has joined are configured for RRC_INACTIVE reception, and the paging message contains the inactiveReceptionAllowed field of the TMGI, and during the RRC connection recovery process initiated in response to the RAN paging, the resumeCause field carried in the RRC recovery request message is set to mt-SDT. Further, if the UE is notified to stop detecting G-RNTI(s) of all joined multicast sessions configured for RRC_INACTIVE reception, and further, if there is no multicast MCCH, and if the cell selected or re-selected by the UE is different from the cell where the multicast service(s) was received in RRC_CONNECTED, then the RRC connection recovery process is initiated for multicast reception. At this time, since the RRC connection recovery process has already been initiated for SDT, the UE cannot initiate the RRC connection recovery process again during the SDT process. How to prevent the UE from initiating the RRC connection recovery process for multicast reception during the SDT process is a problem that needs to be solved.

[0043] In this embodiment of the disclosure, the resumeCause field carried in the RRC recovery request message is set to mt-SDT, which means that the UE has received a paging message containing an mt_SDT indication and meets the condition of starting the RRC connection recovery process for SDT.

[0044] To address at least some of the aforementioned problems, this disclosure provides corresponding embodiments. Specific embodiments will be listed below to illustrate the processing method of the present invention. Furthermore, the embodiments listed below are merely examples and are not intended to limit the scope of the invention.

[0045] The embodiments of this disclosure are described in detail below. The purpose of this embodiment is to prevent the UE from initiating the RRC connection recovery process for MBS multicast reception during the RRC connection recovery process triggered by the mobile-facing SDT because there is no valid PTM configuration for an active MBS multicast session that is configured as RRC_INACTIVE for reception.

[0046] When a UE in RRC_INACTIVE receives a paging message from a base station, if the paging message contains the TMGI of the MBS multicast sessions that the UE has joined, and if the paging message does not trigger the UE to start the RRC connection recovery process (except for the RRC connection recovery process triggered by the inclusion of mt-SDT in the paging message or the RRC connection recovery process where resumeCause is set to mt-SDT), then the following is executed: (1) If all MBS multicast sessions that the UE has joined, indicated by the TMGI included in the paging message, are configured to receive RRC_INACTIVE and the paging message contains the inactiveReceptionAllowed of the TMGI, and if the UE is notified to stop detecting all joined MBS multicast sessions... Furthermore, if the UE selects or reselects a cell different from the cell in which the UE receives the MBS multicast session in RRC_CONNECTED, or if the UE is not configured to receive the multicast session in RRC_CONNECTED, further, if the paging message does not contain mt-SDT, then an RRC connection recovery process is initiated for multicast reception; or (2) if the UE is notified to stop detecting at least one PTM configuration G-RNTI of a multicast session not included in the RRC release message, and if there is no multicast MCCH, and the paging message does not contain mt-SDT, then an RRC connection recovery process is initiated for multicast reception. Wherein, an RRC connection recovery process where resumeCause is set to mt-SDT refers to an RRC connection recovery request message sent by the RRC connection recovery process carrying resumeCause set to mt-SDT. If the paging message does not contain mt-SDT, it can be replaced with "SDT process is not in progress," or "the paging message did not trigger the UE to start the RRC connection recovery process," or "the UE did not start the RRC connection recovery process with resumeCause set to mt-SDT."

[0047] The following is a detailed description.

[0048] Figure 1 is a flowchart schematically illustrating a method performed by a user equipment (UE) according to an embodiment of the present invention. As shown in Figure 1, this embodiment may include the following steps:

[0049] Step 101: The UE receives a paging message from the base station.

[0050] Step 102: Determine if condition A is met. If condition A is met, further determine if condition B is met. If condition B is met, perform at least one of the following operations:

[0051] Operation 1: If conditions C and D are met, then start the RRC connection recovery process.

[0052] Operation 2: If condition D is met, further determine whether condition C is met. If condition C is met, then start the RRC connection recovery process.

[0053] Operation 3: If condition D is not met, then perform at least one of the following operations: 3-1 to 3-3

[0054] Operation 3-1: Start detecting the G-RNTI(s) corresponding to the TMGI(s). It should be noted that the TMGI is included in the paging message, the UE has joined the MBS multicast session indicated by the TMGI, the MBS multicast session indicated by the TMGI is configured to be received in RRC_INACTIVE, and the paging message contains the inactiveReceptionAllowed corresponding to the TMGI.

[0055] Operation 3-2: If the UE is notified to stop detecting all G-RNTI(s) of multicast sessions that have been joined and configured to receive RRC_INACTIVE, further, if there is no multicast MCCH, and if (1) the cell selected or re-selected by the UE is different from the cell where the multicast service(s) was received in RRC_CONNECTED or (2) the UE is not configured to receive any multicast service or multicast session in RRC_CONNECTED, and if condition C is met, then the RRC connection recovery procedure is initiated for multicast reception.

[0056] Operation 3-3: If the following conditions are not met: the UE is notified to stop detecting G-RNTI(s) of all joined multicast sessions configured to receive RRC_INACTIVE, and further, if the following conditions are met: the UE is notified to stop detecting G-RNTI of at least one multicast session and the PTM configuration of the multicast session is not included in the RRC release message (the RRC release message is the most recently received RRC release message), then perform at least one of the following operations: Operation 3-3a and Operation 3-3b.

[0057] Operation 303a: If a multicast MCCH is present, obtain the MBSMulticastConfiguration message from the multicast MCCH.

[0058] Operation 303b: If the multicast MCCH does not appear and condition C is met, then the RRC connection recovery process is initiated for multicast reception.

[0059] The following describes the conditions involved in the embodiments of this disclosure.

[0060] Condition A: The UE is in RRC_INACTIVE and the UE has joined one or more MBS sessions indicated by the TMGI(s) contained in the paging message (i.e., the TMGI(s) contained in the pagingGroupList in the paging message).

[0061] Condition B: The paging message does not contain the PagingRecordList field, or the UE-Identity of all PagingRecord fields in the paging message does not match the UE identifier assigned by the upper layer or the fullI-RNTI stored by the UE, or the UE has initiated an RRC connection recovery procedure with resumeCause set to mt-SDT. It should be noted that the statement "the UE has initiated an RRC connection recovery procedure with resumeCause set to mt-SDT" can be replaced by "the UE has initiated an RRC connection recovery procedure with resumeCause set to mt-SDT" in response to the RAN paging message. The UE has initiated an RRC connection recovery procedure with resumeCause set to mt-SDT. Alternatively, the UE-Identity of the PagingRecord field in the paging message matches the fullI-RNTI stored by the UE, and the paging message contains an mt-SDT indication (i.e., an mt-SDT indication for the UE) and satisfies the conditions for initiating an SDT for a resume procedure initiated in response to RAN paging.

[0062] Condition C: The paging message does not contain an mt-SDT indication (i.e., it does not contain an mt-SDT indication for the UE).

[0063] Condition D: At least one of the MBS sessions to which the UE has joined, as indicated by the TMGI contained in the paging message, is not configured to receive in RRC_INACTIVE, or the inactiveReceptionAllowed of at least one MBS session to which the UE has joined, as indicated by the TMGI contained in the paging message, is not included in the paging message.

[0064] Condition E: The MBS sessions to which the UE has joined, as indicated by the TMGI(s) contained in the paging message, are all configured to be received in RRC_INACTIVE and the inactiveReceptionAllowed of the TMGI is included in the paging message.

[0065] As a variation of this embodiment, condition C can be replaced by one of the following conditions C1-C5:

[0066] Condition C1: In response to the paging message, the UE does not initiate the RRC connection recovery process.

[0067] Condition C2: The UE did not initiate the RRC connection recovery procedure for the mt-SDT purpose.

[0068] Condition C3: There is no ongoing RRC connection recovery process.

[0069] Condition C4: Not satisfied: The UE has initiated the resumeCause RRC connection recovery procedure set to mt-SDT.

[0070] Condition C5: Not satisfied: The ue-Identity of the PagingRecord field contained in the paging message matches the fullI-RNTI stored by the UE, and the paging message contains an mt-SDT indication (i.e., an mt-SDT indication for the UE) and satisfies the condition of initiating an RRC recovery procedure for SDT in response to RAN paging.

[0071] As a variation of this embodiment, the condition D that is not satisfied can be replaced with the condition E that is satisfied.

[0072] As a variation of this embodiment, condition B can be replaced with the following condition B1:

[0073] Condition B1: The paging message does not contain a PagingRecordList field, or the ue-Identity of all PagingRecord fields in the paging message does not match the UE identifier assigned by the upper layer or the fullI-RNTI stored by the UE (except where the ue-Identity of the PagingRecord field matches the fullI-RNTI stored by the UE and the mt-SDT is included in the paging message). Here, mt-SDT being included in the paging message means that the mt-SDT for the UE is included in the paging message.

[0074] When a UE in RRC_INACTIVE receives a paging message from a base station, it checks the PagingRecord contained in the paging message. If the ue-Identity in the PagingRecord matches the fullI-RNTI stored by the UE, and if conditions F1 to F3 are not met, and further, if condition G is met, and any one of conditions H1 to H3 is met, then at least one of the following operations I and II is performed:

[0075] Operation I: Start the RRC connection recovery process and set resumeCause to mt-SDT.

[0076] Operation II: If the following conditions are met: the paging message contains a PagingGroupList field, the UE is configured to receive MBS multicast in RRC_INACTIVE, and the paging message contains inactiveReceptionAllowed for all MBS sessions to which the UE has joined, as indicated by all TMGI(s) in the PagingGroupList, then at least one of operations 3-1 to 3-3 shall be performed.

[0077] The following describes the conditions involved in the embodiments of this disclosure:

[0078] Condition F1: The UE is configured by upper layers with Access Identity 1.

[0079] Condition F2: The UE is configured with Access Identity 2 by upper layers.

[0080] Condition F3: The UE is configured by upper layers with one or more Access Identities equal to 11-15.

[0081] Condition G: The paging message contains an mt-SDT indication (i.e., an mt-SDT indication for the UE) and satisfies the condition of initiating an RRC recovery procedure for SDT in response to a RAN paging.

[0082] Condition H1: The paging message does not contain the PagingGroupList field.

[0083] Condition H2: The paging message contains a PagingGroupList field, but the UE has not joined any MBS session indicated by the TMGI(s) contained in the PagingGroupList.

[0084] Condition H3: The paging message contains a PagingGroupList field, the UE is configured to receive MBS multicast in RRC_INACTIVE, and the paging message contains inactiveReceptionAllowed for all MBS sessions to which the UE has joined, as indicated by all TMGI(s) contained in the PagingGroupList.

[0085] It should be noted that in this embodiment of the disclosure, the condition "the paging message contains inactiveReceptionAllowed for all MBS sessions that the UE has joined indicated by all TMGI(s) in the PagingGroupList" can be replaced with "the paging message contains inactiveReceptionAllowed for all MBS sessions that the UE has joined indicated by all TMGI(s) in the PagingGroupList, and all MBS sessions that the UE has joined indicated by the TMGI(s) are configured to receive RRC_INACTIVE".

[0086] The following describes the process performed by a UE undergoing SDT due to the lack of a valid PTM configuration.

[0087] In one embodiment, while the SDT process is in progress, a UE with SDT capability initiates the following process due to the lack of a valid PTM configuration:

[0088] If an SDT procedure is in progress but the UE does not have a valid PTM configuration, further, if the UE does not transmit a UE Auxiliary Information (UEAssitanceInformation) message containing the nonSDT-DataIndication field after initiating the current RRC recovery procedure for SDT, then the transmission of the UEAssitanceInformation message is initiated to provide nonSDT-DataIndication.

[0089] The following describes the specific operations involved in initiating the transmission of the UEAssitanceInformation message to provide nonSDT-DataIndication.

[0090] If the transmission of a UEAssitanceInformation message is initiated due to the arrival of data and / or signaling indicating that it is mapped to an RB without SDT configuration, or due to an indication that there is no valid PTM configuration, then at least one of the following actions shall be performed:

[0091] Operation A1: Include nonSDT-DataIndication in the UEAssitanceInformation message.

[0092] Operation A2: If the UE initiates the transmission of the UEAssitanceInformation message due to the lack of a valid PTM configuration, the UEAssitanceInformation message includes resumeCause, whose value indicates the absence of a valid PTM configuration. Specifically, the UE can set the value of resumeCause as follows:

[0093] If the UE is configured with access identifier 1 by the upper layer, then the value of resumeCause is set to mps-PriorityAccess; otherwise (i.e., the UE is not configured with access identifier 1 by the upper layer), if the UE is configured with access identifier 2 by the upper layer, then the value of resumeCause is set to mcs-PriorityAccess; otherwise (i.e., the UE is not configured with both access identifier 1 and access identifier 2 by the upper layer), if the UE is configured with one or more of access identifiers 11-15 by the upper layer, then the value of resumeCause is set to highPriorityAccess; otherwise (i.e., the UE is not configured with either access identifier 1 or access identifier 2 by the upper layer, nor with any of access identifiers 11-15 by the upper layer), then the value of resumeCause is set to mt-Access.

[0094] As a variation of the above embodiment, the nonSDT-DataIndication field can replace the noValidPTM-ConfigIndication field, which is used to indicate that the UE does not have a valid PTM configuration or to indicate that the UE receiving a multicast session in RRC_INACTIVE is not configured with a valid PTM configuration for the MBS multicast session received in RRC_INACTIVE.

[0095] In this embodiment of the disclosure, the absence of a valid PTM configuration can be replaced by receiving a multicast session or by the absence of a multicast MCCH. Furthermore, the absence of a valid PTM configuration means that the UE does not have a valid PTM configuration for the multicast session indicated by the TMGI contained in the received paging message, where the multicast session is one the UE has joined and is configured to receive RRC_INAACTIVE, and the inactiveReceptionAllowed corresponding to the multicast session (i.e., its TMGI) is included in the paging message. The UE may consider that it does not have a valid PTM configuration for the multicast session indicated by the TMGI in at least one of the following situations:

[0096] Case 1: Not satisfied: The UE is notified to stop detecting G-RNTI(s) of all multicast sessions that have been joined and configured to be received as RRC_INACTIVE. Furthermore, the UE is notified to stop detecting G-RNTI of at least one multicast session and the PTM configuration of the multicast session is not included in the RRC release message (the RRC release message is the most recently received RRC release message). Furthermore, the multicast MCCH does not appear.

[0097] Case 2: The UE is notified to stop detecting all G-RNTI(s) of multicast sessions that have been joined and configured to be received in RRC_INACTIVE. Furthermore, there is no multicast MCCH and the following conditions are met: (1) the cell selected or re-selected by the UE is different from the cell where the multicast service(s) was received in RRC_CONNECTED; or (2) the UE is not configured to receive any multicast service (or multicast session) in RRC_CONNECTED.

[0098] In this embodiment of the disclosure, the nonSDT-DataIndication field is used to notify the network of the arrival of data and / or signaling mapped to a radio bearer without SDT configuration, and / or, when the SDT process is in progress, to notify the network that the UE does not have a valid PTM configuration. The UEAssistanceInformation message is used to indicate UE assistance information to the network.

[0099] In the existing process, when a UE initiates an RRC connection recovery procedure due to SDT, it will not initiate an RRC connection recovery procedure for MBS multicast reception. This is because after the UE initiates an RRC connection recovery procedure for SDT, the base station may send an RRCReject message to the UE. At this time, although the MBS multicast sessions the UE has joined, indicated by the TMGI in the paging message, are all configured for RRC_INACTIVE reception and the paging message contains the inactiveReceptionAllowed corresponding to the TMGI, the UE may not have a valid PTM configuration for the MBS multicast sessions indicated by the TMGI. Therefore, the UE still needs to initiate the RRC connection recovery procedure. The following embodiments address this issue.

[0100] When the UE receives the RRCReject message, if SDT is in progress, the UE determines whether it needs to initiate the RRC connection recovery process for MBS multicast reception. If so, the UE initiates the RRC connection recovery process for MBS multicast reception.

[0101] In addition, the UE can set an indicator to indicate whether an RRC connection recovery procedure needs to be initiated for MBS multicast reception. Upon receiving an RRCReject message, the UE checks whether the indicator exists (e.g., checks whether the value of the indicator is true). If the indicator exists or its value is set to true, the UE initiates an RRC connection recovery procedure for MBS multicast reception.

[0102] The UE can initialize the value of the indication flag when it receives a paging message or an RRRCRelease message, for example, by setting the value of the indication flag to false.

[0103] The UE can set the value of the indication flag in operation 2-2 of the foregoing embodiment to indicate that an RRC connection recovery procedure needs to be initiated for MBS multicast reception. Accordingly, operation 2-2 is replaced by the following operation 2-2':

[0104] Operation 2-2: If the UE is notified to stop detecting G-RNTI(s) of all multicast sessions that have been joined and configured to be received in RRC_INACTIVE, further, if a multicast MCCH exists, then the detection of multicast MCCH-RNTI begins, and the MBSMulticastConfiguration message is obtained from the multicast MCCH; otherwise (if the existence of a multicast MCCH is not satisfied), if the cell selected or re-selected by the UE is different from the cell where the multicast service(s) was received in RRC_CONNECTED, and mt-SDT is not included in the paging message, then the RRC connection recovery process is initiated for multicast reception. Where mt-SDT is not included in the paging message, it can be replaced with SDT in progress, or with the UE having initiated an RRC connection recovery procedure for SDT; otherwise (if the existence of multicast MCCH is not satisfied), if the cell selected or re-selected by the UE is different from the cell where the multicast service(s) was received in RRC_CONNECTED, but mt-SDT is included in the paging message, the value of the indication flag is set to indicate that there is a value corresponding to the need to initiate an RRC connection recovery procedure for MBS multicast reception, for example, the value of the indication flag is set to true.

[0105] The UE can reset the value of the indicator after initiating the RRC connection recovery process for MBS multicast reception, for example, by setting the value of the indicator to false.

[0106] The UE initiates the RRC connection recovery process to restore a suspended RRC connection or to initiate small data transmissions in an inactive RRC state. During this process, the UE generates an RRC recovery request message and receives response messages from the base station, such as an RRC recovery message, an RRC release message, or an RRC rejection message.

[0107] In this embodiment of the disclosure, the `inactiveReceptionAllowed` field indicates whether the UE with a valid PTM configuration for a TMGI in the `PagingGroupList` stays in `RRC_INACTIVE` to receive the corresponding MBS multicast session. The `pagingGroupList` field contains one or more TMGIs (i.e., a list of TMGIs), and the `PagingRecordList` field contains one or more `PagingRecord` fields (i.e., a list of PagingRecords). The PagingRecord field includes a ue-Identity field, and optionally, an accessType field indicating whether the paging message was initiated from a PDU session not accessed by 3GPP. The ue-Identity field indicates a value of ng-5G-S-TMSI or fullI-RNTI. ng-5G-S-TMSI contains the 5G S Temporary Mobility Identifier, a temporary UE identifier provided by the 5GC (5G core network, i.e., the upper layer) to uniquely identify the UE in the tracking area. The fullI-RNTI indicates a value (I-RNTI-Value) used to identify the suspended UE context of a UE in an RRC inactive state. The resumeCause field provides the reason for the RRC connection restoration request provided by the upper layer or RRC.

[0108] In this embodiment of the disclosure, the conditions for initiating the RRC recovery process for SDT are described in TS38.331-i20.

[0109] In this disclosure, MBS multicast or multicast session or service is MBS multicast session or service.

[0110] Unless otherwise specified, the embodiments executed by the UE or base station in this disclosure can be executed by the RRC entity in the UE or base station or executed at the RRC layer. In this disclosure, fields, domains, information elements, and parameters are used interchangeably. In embodiments of this disclosure, if multiple operations are included, embodiments obtained by changing the execution order of the operations are also within the scope of protection of this disclosure. When multiple parallel judgment conditions are included, embodiments obtained by changing the order of the judgment conditions are also within the scope of protection of this disclosure. The terms "and," "or," "and / or," "and," and "and" in the conditions involved in the embodiments of this disclosure are used interchangeably, and the resulting embodiments are also within the scope of this disclosure.

[0111] Figure 2 is a simplified structural block diagram of the user equipment involved in this invention.

[0112] As shown in Figure 2, the user equipment 20 includes at least a processor 201 and a memory 202. The processor 201 may include, for example, a microprocessor, a microcontroller, an embedded processor, etc. The memory 202 may include, for example, volatile memory (such as random access memory, RAM), a hard disk drive (HDD), non-volatile memory (such as flash memory), or other memory systems. Program instructions are stored on the memory 202. When executed by the processor 201, these instructions can perform one or more steps of the processing method of the UE disclosed herein.

[0113] In the embodiments of this disclosure, when multiple operations are included, the execution order of each operation is exemplarily listed. Embodiments obtained by changing the execution order of each operation are also within the scope of protection of this disclosure. Furthermore, when multiple judgment conditions are included, embodiments obtained by changing the execution order of the judgment conditions are also within the scope of protection of this disclosure.

[0114] Furthermore, the computer-executable instructions or program running on the device according to the invention can be a program that enables the computer to perform the functions of the embodiments of the invention by controlling the central processing unit (CPU). The program or the information processed by the program can be temporarily stored in volatile memory (such as random access memory RAM), hard disk drive (HDD), non-volatile memory (such as flash memory), or other memory systems.

[0115] Computer-executable instructions or programs for implementing the functions of the various embodiments of the present invention can be recorded on a computer-readable storage medium. The corresponding functions can be implemented by causing a computer system to read and execute the programs recorded on the recording medium. The term "computer system" here can refer to a computer system embedded in the device, and may include an operating system or hardware (such as peripheral devices). "Computer-readable storage medium" can be a semiconductor recording medium, an optical recording medium, a magnetic recording medium, a short-time dynamic program storage medium, or any other computer-readable recording medium.

[0116] Various features or functional modules of the devices used in the above embodiments can be implemented or executed by circuits (e.g., monolithic or multi-chip integrated circuits). Circuits designed to perform the functions described in this specification may include general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination of the above devices. A general-purpose processor may be a microprocessor, or any existing processor, controller, microcontroller, or state machine. The above circuits may be digital circuits or analog circuits. In cases where advancements in semiconductor technology have led to new integrated circuit technologies that replace existing integrated circuits, one or more embodiments of the present invention may also be implemented using these new integrated circuit technologies.

[0117] Furthermore, the present invention is not limited to the embodiments described above. Although various examples of the embodiments have been described, the present invention is not limited thereto. Fixed or non-mobile electronic devices installed indoors or outdoors can be used as terminal devices or communication devices, such as AV equipment, kitchen equipment, cleaning equipment, air conditioners, office equipment, vending machines, and other household appliances.

[0118] As described above, embodiments of the present invention have been described in detail with reference to the accompanying drawings. However, the specific structure is not limited to the above embodiments, and the present invention also includes any design modifications that do not depart from the spirit of the invention. Furthermore, various modifications can be made to the present invention within the scope of the claims, and embodiments obtained by appropriately combining the technical means invented in different embodiments are also included within the technical scope of the present invention. In addition, components with the same effects described in the above embodiments can be substituted for each other.

Claims

1. A method executed by a user equipment (UE), comprising: Step 1: The UE receives a paging message from the base station; and Step 2: If conditions A and B are met, perform at least one of the following operations: 1 through 3 Operation 1: If conditions C and D are met, then initiate the RRC connection recovery process; Operation 2: If condition D is met, further determine whether condition C is met. If condition C is met, then start the RRC connection recovery process. Operation 3: If condition D is not met, then perform at least one of the following operations: 3-1 to 3-3 Operation 3-1: Start detecting the G-RNTI(s) corresponding to the TMGI(s); Operation 3-2: If the UE is notified to stop detecting G-RNTIs of all multicast sessions that have been joined and configured to receive RRC_INACTIVE, further, if there is no multicast MCCH, and if (1) the cell selected or reselected by the UE is different from the cell in which the UE received multicast services when RRC_CONNECTED, or (2) the UE is not configured to receive any multicast services when RRC_CONNECTED, and if condition C is met, then the RRC connection recovery process is started for multicast reception; Operation 3-3: If the following conditions are not met: the UE is notified to stop detecting G-RNTI(s) of all multicast sessions that have been joined and configured to receive RRC_INACTIVE, further, if the following conditions are met: the UE is notified to stop detecting G-RNTI of at least one multicast session and the PTM configuration of the multicast session is not included in the RRC release message, then the following operation is performed: if the multicast MCCH does not appear and condition C is met, then the RRC connection recovery process is started for multicast reception; Wherein, condition A is that the UE is in RRC_INACTIVE and the UE has joined one or more MBS sessions indicated by the TMGI contained in the paging message; Condition B is that the paging message does not contain the PagingRecordList field, or the ue-Identity of all PagingRecord fields contained in the paging message does not match the UE identifier assigned by the upper layer or the fullI-RNTI stored by the UE, or the UE has started the RRC connection recovery process with resumeCause set to mt-SDT. Condition C is that the paging message does not contain an mt-SDT indication; Condition D is that at least one of the MBS sessions to which the UE has joined, as indicated by the TMGI contained in the paging message, is not configured to receive in RRC_INACTIVE, or that the inactiveReceptionAllowed of at least one MBS session to which the UE has joined, as indicated by the TMGI contained in the paging message, is not included in the paging message.

2. A user equipment, comprising: processor; as well as Memory, which stores instructions The above instructions are executed by the processor according to any one of claims 1.

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