Method performed by user equipment (UE) in RRC_inactive state, and ue

Abstract

The present disclosure provides a method performed by a user equipment (UE) in an RRC_INACTIVE state, and a UE. The method method performed by a UE in an RRC_INACTIVE state comprises: the UE receives an SIB1 from a base station and saves the SIB1; and when related information in the SIB1 is forwarded to an upper layer and the forwarded information does not cause the upper layer to trigger message transmission, if the UE is configured to receive MBS multicast in RRC_INACTIVE, and further, if SIB24 is not scheduled in the SIB1 on a new cell after cell selection or reselection, starting an RRC connection recovery process, the new cell after the cell selection or cell reselection being a cell different from the cell in which the UE receives an MBS multicast session in RRC_CONNECTED.

Description

Method performed by a user equipment in an RRC_INACTIVE state and user equipment TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, and more particularly, to a method performed by a user equipment and a user equipment. BACKGROUND

[0002] A study item (SI) on architecture improvement for 5G multicast broadcast service (see SP-190625 for details) has been approved. One of the objectives of this SI (referred to as objective A) is to support generic MBS services in 5GS, and 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 delivery, group communications, and Internet of Things applications, etc. Accordingly, at the 3rd Generation Partnership Project (3GPP) RAN #86 plenary meeting, a work item on NR multicast and broadcast service (see Non-Patent Literature: RP-193248: New WID: NR Multicast and Broadcast Service) was proposed and approved. This work item aims to provide support for objective A in the RAN. The objectives of this work item have been basically achieved, and the detailed description of the related solutions can be found in the 3GPP Release 17 technical documents, such as TS 38.300-h70, TS 38.331-h70, TS 38.321-h70, etc. At the 3GPP RAN #94 plenary meeting, a work item named Enhancements of NR Multicast and Broadcast Services was approved (see Non-Patent Literature: RP-213568: New WID: Enhancements of NR Multicast and Broadcast Services). This work item aims to further enhance the MBS broadcast multicast of Release 17, and one of its objectives is to support user equipment receiving MBS multicast services / sessions in an RRC inactive state.

[0003] The present application discusses related issues involved in supporting user equipment receiving MBS multicast services / sessions in an RRC inactive state by the RAN. SUMMARY

[0004] To solve at least part of the above problems, the present application provides a method performed by a user equipment and a user equipment.

[0005] According to a first aspect of the present application, a method performed by a user equipment (UE) in RRC_INACTIVE is provided, comprising: the UE receiving a SIB1 from a base station and saving the SIB1; in case that the UE is configured to receive MBS multicast in RRC_INACTIVE and there is at least one MBS multicast session not indicated as stop detecting G-RNTI, and the UE forwards the relevant information in the SIB1 to upper layer and the forwarded information does not cause the upper layer to trigger message transmission, further, if there is no SIB24 scheduled in the SIB1 on the new cell after cell selection or reselection, starting a RRC connection resume procedure; wherein the new cell after cell selection or cell reselection is a cell different from a reference cell.

[0006] In the above method related to the first aspect of the present application, the reference cell is a PCell (primary cell) when the UE receives an RRCRelease message, or a PCell when the UE is in RRC_CONNECTED, or a cell where the UE receives an MBS multicast session when the UE is in RRC_CONNECTED, or if the UE is configured with an MBS multicast session when the UE is in RRC_CONNECTED, the reference cell is a cell where the UE receives an MBS multicast session when the UE is in RRC_CONNECTED; otherwise, the reference cell is a PCell when the UE is in RRC_CONNECTED or a PCell when the UE receives an RRCRelease message or a cell where the UE receives an RRCRelease message, or a cell indicated in the received RRCRelease message, or a cell where a PTM configuration configured in the received RRCRelease message is applied.

[0007] Further, according to a second aspect of the present application, a method performed by a user equipment (UE) is provided, comprising: the UE receiving an RRCRelease message from a base station; if a multicastConfigInactive field contained in the RRCRelease message is set to "setup", further, if the RRCRelease message provides a multicast PTM configuration for a multicast session not indicated as stop detecting G-RNTI, and A1 or A2 is satisfied, applying the multicast PTM configuration and / or detecting a multicast MCCH-RNTI; wherein,

[0008] A1: the UE is configured with an MBS multicast session when the UE is in RRC_CONNECTED, and the cell selected by the UE is a cell where the UE receives the MBS multicast session when the UE is in RRC_CONNECTED;

[0009] A2: the UE is not configured with a MBS multicast session in RRC_CONNECTED and the cell selected by the UE is the cell where the UE receives the RRC release message or the primary cell (PCell) or the PCell at the time the UE receives the RRC release message or the PCell at the time the UE is in RRC_CONNECTED.

[0010] Further, according to the third aspect of the present application, a user equipment is provided, comprising: a processor; and a memory storing instructions, wherein the instructions, when executed by the processor, perform the method described above.

[0011] According to the method performed by the user equipment and the user equipment, the user equipment in RRC_INACTIVE can determine whether the cell after performing cell selection or cell reselection is a new cell, and the user equipment can determine whether to apply the PTM configuration when receiving the RRC release message containing the PTM configuration, and the user equipment in RRC_INACTIVE can determine whether to acquire the MBS multicast configuration message when moving to the cell providing SIB24 when receiving the MBS multicast in RRC_INACTIVE. BRIEF DESCRIPTION OF DRAWINGS

[0012] The above and other features of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:

[0013] Fig. 1 is a schematic flowchart illustrating a method performed by a user equipment according to an embodiment of the present application.

[0014] Fig. 2 is a schematic flowchart illustrating a method performed by a user equipment according to another embodiment of the present application.

[0015] Fig. 3 is a block diagram illustrating a user equipment according to an embodiment of the present application. DETAILED DESCRIPTION

[0016] Some terms related to the present application are described below, and the specific meanings of the terms can be found in the latest relevant documents of 3GPP, such as TS38.300, TS38.321, TS38.323, TS38.331, etc. In addition, the embodiments of the present application are described by taking broadcast / multicast services as an example, but the embodiments of the present application are not limited to broadcast / multicast services, and can also be applied to other application scenarios.

[0017] UE: User Equipment, user equipment.

[0018] RRC: Radio Resource Control, radio resource control.

[0019] RRC_CONNECTED: RRC connected state.

[0020] RRC_INACTIVE: RRC inactive state.

[0021] RRC_IDLE: RRC idle state.

[0022] RAN: Radio Access Network.

[0023] NR: New RAT, New Radio Access Technology.

[0024] MBS: Multicast / Broadcast Services.

[0025] AS: Access Stratum.

[0026] NAS: Non Access Stratum.

[0027] RB: Radio Bearer.

[0028] MRB: MBS Radio Bearer, a radio bearer that is configured for MBS delivery.

[0029] TMGI: Temporary Mobile Group Identity.

[0030] RNTI: Radio Network Temporary Identifier.

[0031] PTM: Point to Multipoint, a delivery mode of MBS service. In PTM delivery mode, a gNB delivers a single copy of MBS data packets to a set of UEs. A UE uses a G-RNTI or a G-CS-RNTI to receive PTM transmission. For example, a gNB schedules the same group-common physical downlink shared channel (PDSCH) using a group-common physical downlink control channel (PDCCH) with a G-RNTI.

[0032] PCell: Primary Cell, a MCG cell, operating on a primary frequency, in which a UE performs an initial connection establishment procedure or initiates a connection re-establishment procedure.

[0033] Dual connectivity or multi-connectivity: refers to a UE in RRC_CONNECTED state that has established a radio access with more than one network node and is capable of data transmission over the physical radio access. In dual connectivity, a UE with multiple Tx / Rx capability is configured to use resources provided by two network nodes connected through non-ideal backhaul. One of the network nodes acts as the master node (MN or MN gNB) and the other as the secondary node (SN or SN gNB). The MN and SN are connected through a network interface and at least the MN is connected to the core network. The MN can be implemented by one gNB / eNB / ng-eNB, and the group of serving cells controlled by the MN is referred to as the master cell group (MCG), i.e., the MCG is associated with the MN. The MCG contains at least one primary serving cell operating on a primary frequency, referred to as the primary cell (PCell), over which the UE performs the initial connection establishment procedure or initiates the connection re-establishment procedure. The MCG can also contain other cells, which are collectively referred to as secondary serving cells (SCells). Correspondingly, the SN can be implemented by one or more gNBs / eNBs / ng-eNBs, and the group of serving cells controlled by the SN is referred to as the secondary cell group (SCG), i.e., the SCG is associated with the SN. The SCG contains at least one primary serving cell, referred to as the primary secondary cell (PSCell). The UE performs random access (if needed) on the PSCell when performing a synchronization reconfiguration (synchronization reconfiguration for SCG or SCG change) procedure. The SCG can also contain other cells, which are collectively referred to as SCells. In this disclosure, SpCell can refer to the PCell of the MCG or the PSCell of the SCG.

[0034] G-RNTI: Group RNTI, used to scramble the scheduling and transmission of PTM for one or more MBS multicast services.

[0035] G-CS-RNTI: Group Configured Scheduling RNTI, used to scramble the semi-persistent scheduling (SPS) group-common physical downlink shared channel (PDSCH) and the activation / deactivation of the SPS group-common PDSCH for one or more MBS multicast services.

[0036] MTCH: MBS Traffic Channel, MBS traffic channel, is a PTM downlink channel used for transmitting MBS data of multicast session or broadcast session from the network to the UE. Unless otherwise specified, the MTCH involved in the embodiments of the present disclosure refers to the multicast MTCH used for transmitting the MBS multicast session.

[0037] MCCH: MBS Control Channel, MBS control channel, is a PTM downlink channel used for transmitting MBS broadcast or MBS multicast control information associated to one or several MTCH(s)from the network to the UE. The MCCH includes broadcast MCCH and multicast MCCH. Unless otherwise specified, the MCCH involved in the embodiments of the present disclosure refers to the multicast MCCH.

[0038] RRCResumeRequest or RRCResumeRequestl is used to request to resume a suspended RRC connection or to perform a RAN-based notification area, RNA, update. The UE uses the RRCResumeRequestl message and sets the resumeIdentity field in the RRCResumeRequestl message to the UE stored full I-RNTI, if the useFullResumeID field is included in the SIB1 received from the camped or serving cell or the cell performing the RRC resume procedure, or uses the RRCResumeRequest and sets the resumeIdentity field in the RRCResumeRequest message to the stored short I-RNTI, otherwise, when initiating the RRC connection resume request. The RRCRelease message is used to order the release of one RRC connection or to suspend one RRC connection. The RRCReconfiguration message is used to order the modification of an RRC connection. The RRCSetup message is used to establish SRB1. SRB1 is used for RRC messages, which can include piggybacked NAS messages, and for NAS messages before SRB2 is established, both use the dedicated control channel, DCCH, logical channel. The RRCResume message is used to resume a suspended RRC connection. In this disclosure, the useFullResumeID field indicates the resume identity and resume request message to use, when the field is included in SIB1, the full I-RNTI and RRCResumeRequestl message are used, when the field is not included in SIB1, the short I-RNTI and RRCResumeRequest message are used. The short I-RNTI uses fewer bits than the I-RNTI-Value, i.e. full I-RNTI, to identify the suspended UE context of a UE in RRC inactive state. The RRC resume procedure, i.e. RRC connection resume procedure, is used to resume a suspended RRC connection, including resuming SRB(s), DRB(s) and multicast MRB(s), or to perform an RNA update, or to implement an MBS multicast reception request, or to initiate small data transmission, SDT, in RRC_INACTIVE state, etc. In the RRC resume procedure, the UE sends the RRC resume request message to the base station and can receive the RRC resume message RRCResume or the RRC setup message RRCSetup or the RRC release message RRCRelease or the RRC reject message RRCReject from the base station.

[0039] In the present application, network, base station and RAN are used interchangeably, and the network can be a long term evolution (LTE) network, a NR network, an enhanced long term evolution (eLTE) network, or other network defined in subsequent evolution versions of 3GPP.

[0040] Currently, the NR MBS service includes MBS broadcast (also referred to as MBS broadcast session or broadcast MBS or MBS broadcast service or MBS broadcast service) and MBS multicast (also referred to as MBS multicast session or multicast MBS or MBS multicast service or MBS multicast service). The MBS broadcast provides a downlink-only MBS transmission mode for low quality of service (QoS) services, so that UEs in RRC connected state, RRC idle state and RRC inactive state can all receive the MBS service. The UE obtains the MBS broadcast configuration information broadcast by the network through the MBS control channel (MCCH).

[0041] In Rel-17, UE is not supported to receive MBS multicast session in RRC inactive state. Therefore, UE needs to establish RRC connection with the base station before receiving MBS multicast service (i.e. MBS multicast session), and then the UE is configured by the base station (i.e. network) through dedicated RRC signaling (also called RRC message, e.g. RRC reconfiguration message) to receive the resource or PTM configuration of MBS multicast service, and the MBS radio bearer (MRB) for receiving these MBS multicast services is also configured by the base station through dedicated RRC signaling for the UE. Only the UE in RRC connected state and configured with MRB can receive the corresponding MBS multicast service. The base station can send MBS multicast service in PTM mode or PTP mode. Using PTM mode to send MBS multicast service means that the transport block containing MBS multicast session data is addressed by G-RNTI (or the PDCCH scheduling the transport block is addressed or scrambled by G-RNTI), while using PTP mode to send MBS multicast service means that the transport block containing MBS multicast session data is addressed by C-RNTI (or the PDCCH scheduling the transport block is addressed or scrambled by C-RNTI). Therefore, when a MBS multicast session is activated by the core network or the base station has MBS multicast session data to send, the network supporting MBS multicast notifies the UE in RRC idle state or RRC inactive state through a group notification mechanism. Upon receiving the group notification, the UE that has joined or is interested in the MBS multicast session establishes or resumes RRC connection with the network to receive the corresponding MBS multicast session. The group notification is addressed with P-RNTI on PDCCH, and the UE monitors the paging channel. The paging message for group notification contains MBS session identification TMGI, which is used to page all UEs that have joined the related MBS multicast session and are in RRC idle state or RRC inactive state. In other words, the base station does not individually page the UE (for the purpose of receiving MBS multicast session).

[0042] In Release 18, UE is supported to receive MBS multicast session in RRC inactive state. For MBS multicast session configured for RRC inactive state reception, the base station can provide or configure the PTM configuration information (also referred as configuration information of MBS multicast session or PTM configuration of MBS multicast session or MBS multicast configuration) for UE to receive the MBS multicast session through dedicated RRC signaling (e.g. RRCRelease message) or through multicast MBS control channel MCCH (i.e. multicast MCCH). While the information required to acquire the multicast MCCH (or multicast MCCH configuration) can be configured for UE through dedicated RRC signaling or system information block (denoted as SIB24), i.e. SIB24 contains the information required to acquire the configuration of multicast MCCH / MTCH (i.e. MCCH and / or MTCH) for RRC inactive state MBS multicast reception. The PTM configuration information can include the configuration information of MRB corresponding to the MBS multicast session and / or the identification TMGI of the MBS multicast session and its corresponding G-RNTI / G-CS-RNTI and / or DRX and / or other configuration information. For example, the PTM configuration of a certain MBS multicast session is the information contained in MBSMulticastConfiguration message related to the reception of the MBS multicast session. Wherein, 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 multicast MCCH or contained in RRC release message. Wherein, the multicast MCCH is an APTM downlink channel used for transmitting control information of MBS multicast session associated to one or several MTCH(s) from the network to the UE in RRC_INACTIVE state.For the MBS multicast session received in RRC_INACTIVE state, the MBS multicast session in the embodiment of the present disclosure is in the active state or activated, which means that the MBS multicast session is ongoing or about to start, the UE starts to receive (or is receiving) the MBS multicast session or the UE starts to detect the G-RNTI corresponding to the MBS multicast session or the UE starts to monitor the multicast MCCH-RNTI of the multicast MCCH. The network can indicate the UE that the MBS multicast is activated or resumes data transmission through the multicast MCCH or RRC signaling (such as RRC release message) or through the paging message. For example, the TMGI of the MBS multicast session is included in the paging message, which means that the MBS multicast session is activated or resumes data transmission, and the stopMonitoringRNTI field of the MBS multicast session is not included in the multicast MCCH or RRC release message, which means that the MBS multicast session is activated or resumes data transmission, wherein the stopMonitoringRNTI field is used to indicate the UE to stop detecting the G-RNTI corresponding to the multicast session. The UE starts to receive the MBS multicast session after receiving the indication that the MBS multicast is activated or resumes data transmission (i.e., the UE starts to detect the G-RNTI corresponding to the MBS multicast session). The MBS multicast activated in the embodiment of the present disclosure also applies to the case of resuming the data transmission of the MBS multicast session, which will not be described below. The MBS multicast session in the embodiment of the present disclosure is in the inactive state or deactivated, which means that the MBS multicast session has ended or paused data transmission or the UE stops 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 for each MBS multicast session in the multicast MCCH message to explicitly indicate the UE to stop detecting the G-RNTI corresponding to the MBS multicast session (i.e., to indicate that the MBS multicast session is deactivated or stops data transmission). The UE stops receiving the MBS multicast session after receiving the indication. The UE stops receiving the MBS multicast session can be that the UE stops detecting the G-RNTI or G-CS-RNTI corresponding to the MBS multicast session. Therefore, in the present disclosure, the indication that the MBS multicast session is deactivated or stops data transmission is the indication that the UE stops detecting the G-RNTI or G-CS-RNTI associated with the MBS multicast session. In addition, the indication that the MBS multicast session is activated or resumes data transmission is the indication that the UE starts to detect the G-RNTI corresponding to the MBS multicast session, i.e., the MBS multicast session is not indicated to stop detecting the G-RNTI. The MBS multicast session is deactivated, which includes the case that the MBS multicast session has no data transmission temporarily, and the MBS multicast session is activated, which includes the case that the MBS multicast session resumes data transmission.In this disclosure, a multicast session or service is MBS multicast session or service. The following embodiments are illustrated by taking G-RNTI as an example, and the embodiments obtained by replacing G-RNTI with G-CS-RNTI are also within the scope of this disclosure.

[0043] Each MBS multicast session is identified by a TMGI and is associated with a G-RNTI or G-CS-RNTI. A UE receives a MBS multicast session by detecting the G-RNTI or G-CS-RNTI associated with the MBS multicast session.

[0044] For a UE configured with MBS multicast sessions that can be received in RRC_INACTIVE state, when a MBS multicast session is activated or resumes data transmission, if the MBS multicast session is configured and / or allowed to be received in RRC_INACTIVE state and / or the UE is in (valid) PTM configuration with the MBS multicast session, the UE can directly receive the MBS multicast session without establishing RRC connection with the base station. The network can configure the PTM configuration information (e.g., contained in MBSMulticastConfiguration message) of the MBS multicast session received in RRC_INACTIVE state for the UE through multicast MCCH and / or dedicated RRC signaling (e.g., RRC release message, RRC reconfiguration message). The MBS multicast configuration message MBSMulticastConfiguration can be transmitted on the multicast MCCH (at this time the MBSMulticastConfiguration message can be referred to as the multicast MCCH message), or can be contained in the RRC release message. If the RRC release message is used to configure the PTM configuration information of the MBS multicast session received in RRC_INACTIVE state for the UE, the network can contain the MBSMulticastConfiguration message in the RRC release message sent to the UE.

[0045] In the embodiments of the present disclosure, the Multicast MCCH-RNTI (i.e. Multicast MCCH-RNTI) is used for dynamically scheduled Multicast MCCH signaling and / or Multicast MCCH change notification or for dynamically scheduled MCCH signaling and / or MCCH change notification or for scrambling the CRC of DCI or DCI format or for scrambling the PDCCH for MBS multicast transmission purpose or for scrambling the CRC of DCI or DCI format for MBS multicast purpose or for scheduling the PDSCH transmitting MBS multicast session. The DCI or DCI format can be DCI format 4_0 or DCI format 4_1.

[0046] The UE receives the RRC release message from the base station, and when the multicastConfigInactive field is contained 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 the multicast sessions or services that the UE can receive when in RRC_INACTIVE or the multicast sessions or services that the UE can receive in the current serving cell (i.e. the cell receiving the RRC release message).

[0047] In the present disclosure, the role of the multicastConfigInactive field is replaced by one of the following embodiments, which is also within the scope of the present disclosure:

[0048] The multicastConfigInactive field indicates the multicast sessions or services that the UE can receive in the current serving cell when in RRC_INACTIVE, or the multicastConfigInactive field is used to indicate the multicast sessions or services that the UE can receive when in RRC_INACTIVE, or the multicastConfigInactive field is used to indicate the multicast sessions or services that the UE can receive in the current serving cell when in RRC_INACTIVE before acquiring the Multicast MCCH, or the multicastConfigInactive field is used to indicate the multicast sessions or services that the UE can receive when in RRC_INACTIVE before acquiring the Multicast MCCH, or the multicastConfigInactive field is used to indicate the multicast sessions or services that the UE can receive in the serving cell when in RRC_INACTIVE, and the serving cell is the cell receiving the multicast sessions or services when in RRC_CONNECTED.

[0049] Optionally, the multicastConfigInactive field also contains the corresponding configuration of these multicast sessions. (Or the configuration of the MBS multicast service for the current serving cell or the configuration of the MBS multicast service valid for the current serving cell), the current serving cell refers to the cell where the UE receives the RRC release message or the cell where the UE receives the MBS multicast session in RRC_CONNECTED. The serving cell or the cell where the UE last or previously receives the RRC release message can refer to the cell where the UE last or previously receives the RRC release message or the primary cell PCell or the cell where the UE receives the MBS multicast session in RRC_CONNECTED.

[0050] The multicastConfigInactive field can contain two fields, namely the inactivePTM-Config field and the inactiveMCCH-Config field. The inactivePTM-Config field indicates the PTM configuration in the serving cell for receiving MBS multicast in RRC_INACTIVE, which carries the MBSMulticastConfiguration message. The inactiveMCCH-Config field carries the system information SIB24.

[0051] Currently, it can be achieved by including the TMGI of the MBS multicast session in the paging message to indicate the UE to start detecting the G-RNTI of the MBS multicast session (i.e. if the UE receives the paging message containing a TMGI of an MBS multicast session allowed / configured to be received in RRC_INACTIVE, it means that the UE receives the indication to start detecting the G-RNTI of the MBS multicast session). It can also be indicated in the MBSMulticastConfiguration message whether to stop detecting the G-RNTI corresponding to the MBS multicast session. Specifically, for the MBS multicast session whose TMGI is included in the MBSMulticastConfiguration message, if the MBSMulticastConfiguration message further contains the stopMonitoringRNTI field of the MBS multicast session, it means that the UE receives the indication to stop detecting the G-RNTI (i.e. stop detecting the G-RNTI of the MBS multicast session) of the MBS multicast session. Otherwise (i.e. the MBSMulticastConfiguration message does not contain the stopMonitoringRNTI field of the MBS multicast session), it means that the UE does not receive the indication to stop detecting the G-RNTI of the MBS multicast session. The stopMonitoringRNTI field indicates the UE to stop detecting the G-RNTI of the corresponding MBS multicast session. By associating / configuring a stopMonitoringRNTI field for each MBS multicast session, it indicates to stop detecting the G-RNTI of the MBS multicast session. If an MBS multicast session is not associated / configured with a corresponding stopMonitoringRNTI field, it means that the MBS multicast session is not indicated to stop detecting the G-RNTI. The MBSMulticastConfiguration message can be transmitted on the multicast MCCH or included in the RRC release message. Specifically, the MBSMulticastConfiguration message can be included in the MulticastConfigInactive field in the suspendConfig field of the RRC release message.The suspendConfig field indicates the configuration of the RRC_INACTIVE state. If the UE receives an RRC release message containing the MBSMulticastConfiguration message or the MulticastConfigInactive field, it is considered that the UE is configured to receive the MBS multicast or multicast session in the RRC_INACTIVE state. Or if the UE receives an RRC release message (or the MBSMulticastConfiguration message contained in the RRC release message) containing a TMGI, it is considered that the UE is configured to receive the MBS multicast in the RRC_INACTIVE state. It should be noted that the acquisition of the multicast MCCH by the UE refers to the acquisition of the MBSMulticastConfiguration message by the UE from the multicast MCCH.

[0052] Whether a cell or base station provides (i.e., supports) the multicast MCCH is optional, in other words, even if the base station or cell configures the UE to receive the MBS multicast session in the RRC_INACTIVE state, it does not necessarily broadcast the multicast MCCH. The configuration information of the multicast MCCH can be configured through SIB24, and if the base station does not provide (i.e., does not support) the multicast MCCH, the base station or cell can or can not provide SIB24, in which case SIB24 will not be scheduled by SIB1 of the base station or cell.

[0053] A UE in RRC_INACTIVE initiates RRC connection resume procedure when it acquires SIB1, forwards the relevant information in the SIB1 (e.g. cellIdentity for explicitly identifying a cell within one PLMN / SNPN, trackingAreaCode for indicating the tracking area code of the cell indicated by cellIdentity field, PLMN identity or SNPN identity or PNI-NPN identity) to upper layer and the forwarded information does not cause upper layer to trigger message transmission, if the UE is configured to receive MBS multicast in RRC_INACTIVE and at least one MBS multicast session is not indicated to stop detecting G-RNTI (in other words, at least one active MBS session is configured to be received in RRC_INACTIVE state, or at least one MBS multicast session configured to be received in RRC_INACTIVE is not indicated to stop detecting G-RNTI, or the UE is configured to receive one or more MBS multicast sessions in RRC_INACTIVE state, at least one of which is in active state or is not indicated to stop detecting G-RNTI), and further if SIB24 is not scheduled in the SIB1 in the new cell after cell selection or reselection (or in the new cell selected or reselected after performing cell selection or cell reselection, SIB24 is not scheduled in the SIB1, the new cell selected or reselected is the cell in which the UE receives the SIB1), the UE initiates RRC connection resume procedure. In carrier aggregation (CA) scenario, when a UE in RRC_CONNECTED state and configured with CA receives an RRC release message from the base station indicating the UE to enter RRC_INACTIVE state, the UE performs cell selection and reads SIB1 from the selected cell as needed. At this time, if the UE selects a new cell and SIB24 is not scheduled in the SIB1, the UE determines whether to initiate RRC connection resume procedure according to whether the set conditions are met. However, since the UE is configured with CA (i.e. the UE works on multiple cells) in RRC_CONNECTED state, it is a problem to be solved to determine which cell (referred to as reference cell or original cell or old cell) to judge whether the selected or reselected cell is a new cell.

[0054] In the present disclosure, "select" can be replaced by "select or reselect". The SIB24 is not scheduled in the SIB1 in the selected or reselected new cell means that the SIB1 is acquired from the selected or reselected new cell, and the SIB24 is not scheduled in the SIB1. The SIB1 schedules the SIB24 means that the SIB24 is contained in the field SI-SchedulingInfo broadcasted or contained by the SIB1. Correspondingly, the SIB1 does not schedule the SIB24 means that the SIB24 is not contained in the field SI-SchedulingInfo broadcasted or contained by the SIB1. The SI-SchedulingInfo contains information for acquiring SI messages. The SIB1 is one of the system information broadcasted by a cell. The SIB1 contains information relevant when evaluating if a UE is allowed to access a cell and defines the scheduling of other system information. It also contains radio resource configuration information that is common for all UEs and barring information applied to the unified access control.

[0055] In view of the problems in the prior art, the present disclosure proposes the following embodiments, but the following embodiments are only used for illustration and do not limit the protection scope of the present disclosure.

[0056] Embodiment 1

[0057] As shown in FIG. 1, at step 101, the UE in RRC_INACTIVE receives SIB1 from a base station and saves the SIB1.

[0058] In step 103, in the case that the UE is configured to receive MBS multicast in RRC_INACTIVE and there is at least one MBS multicast session (i.e. there is at least one MBS multicast session among the MBS multicast sessions configured for the UE to receive in RRC_INACTIVE) not indicated to stop detecting G-RNTI, and in the case that SIB24 is not scheduled in SIB1 in the new cell after cell selection, start the RRC connection resume procedure (or start the RRC connection resume for MBS multicast reception), wherein the new cell is a cell different from the PCell at which the UE receives (i.e. the latest or previous time the UE receives) the RRCRelease message.

[0059] In the present disclosure, the cell (i.e. the cell after performing cell selection or cell reselection) against which the UE determines whether the cell after cell selection or reselection is a new cell (i.e. the original cell) is referred to as the reference cell. For example, the reference cell in embodiment 1 is the PCell at which the UE receives (i.e. the latest or previous time the UE receives) the RRCRelease message. Here, the RRC release message can be received from the PCell or from an SCell. At this time, the new cell is a cell different from the reference cell.

[0060] Variations of embodiment 1

[0061] By setting different reference cells to determine whether the UE selects or reselects to a new cell, a plurality of variations of embodiment 1 can be obtained, for example:

[0062] Variation 1: The new cell in step 103 is a cell different from the PCell at which the UE is in RRC_CONNECTED (i.e. the latest or previous time the UE is in RRC_CONNECTED). In other words, the reference cell is the PCell at which the UE is in RRC_CONNECTED (i.e. the latest or previous time the UE is in RRC_CONNECTED).

[0063] Variation 2: The new cell in step 103 is a cell different from the cell in which the UE received the MBS multicast session in RRC CONNECTED (i.e. the last time or previously in RRC CONNECTED). In other words, the reference cell is the cell in which the UE received the MBS multicast session in RRC CONNECTED (i.e. the last time or previously in RRC CONNECTED).

[0064] Variation 3: If the UE has a cell in RRC CONNECTED in which the UE received the MBS multicast session (or the UE was configured with the MBS multicast session in RRC CONNECTED, or the UE had the MBS multicast session before being released to RRC INACTIVE, or the UE had or is receiving the MBS multicast session before receiving the RRC release message), the new cell in step 103 is a cell different from the cell in which the UE received the MBS multicast session in RRC CONNECTED (i.e. the last time or previously in RRC CONNECTED); otherwise, the new cell in step 103 is a cell different from the PCell of the UE in RRC CONNECTED or the new cell in step 103 is a cell different from the PCell of the UE in which the UE received (i.e. the last time or previously received) the RRC release message or the new cell in step 103 is a cell different from the cell in which the UE received (i.e. the last time or previously received) the RRC release message. In other words, if the UE has a cell in RRC CONNECTED in which the UE received the MBS multicast session (or the UE was configured with the MBS multicast session in RRC CONNECTED, or the UE had the MBS multicast session before being released to RRC INACTIVE, or the UE had or is receiving the MBS multicast session before receiving the RRC release message), the reference cell is the cell in which the UE received the MBS multicast session in RRC CONNECTED (i.e. the last time or previously in RRC CONNECTED); otherwise, the reference cell is the PCell of the UE in RRC CONNECTED or the cell in which the UE received (i.e. the last time or previously received) the RRC release message or the PCell of the UE in which the UE received (i.e. the last time or previously received) the RRC release message.

[0065] Variation 4: The new cell in step 103 is a cell different from the cell indicated in the RRC release message received (or the last time or previously received) by the UE. In other words, the reference cell is the cell indicated in the RRC release message received by the UE. Wherein the cell indicated in the RRC release message is the cell to which the PTM configuration carried in the RRC release message is applied, in other words, the PTM configuration carried in the RRC release message is configured for the cell.

[0066] Variation 5: The new cell in step 103 is a cell different from the cell to which the PTM configuration carried by the RRC release message received (or last received or previously received) by the UE is applied. In other words, the reference cell is a cell to which or for which the PTM configuration carried or included or configured in the RRC release message received (i.e. last received or previously received) by the UE is applied.

[0067] Optionally, in embodiment 1 and its variations, in the following case, although the cell selected or reselected by the cell selection or cell reselection (i.e. the cell selected or reselected by performing the cell selection or cell reselection) is the reference cell, the UE considers the cell selected or reselected by the cell selection or cell reselection as a new cell:

[0068] If the cell selected or reselected by the cell selection or cell reselection performed by the UE is the reference cell, but the UE has selected or reselected or camped on other cells after receiving the RRC release message and / or before performing the current cell selection or cell reselection. In other words, the UE has selected or reselected (or camped on) other cells different from the reference cell after receiving the RRC release message (i.e. the UE has selected or reselected (or camped on) other cells after receiving the RRC release message, and then selected or reselected the reference cell again.

[0069] In the embodiments of the present disclosure, the condition: if the SIB1 does not schedule SIB24, can be replaced by: if the SIB1 of the selected cell or reselected cell does not schedule SIB24 or if the SIB1 of the camped cell does not schedule SIB24. The embodiments obtained after replacing the condition are still within the scope of protection of the present disclosure. Wherein the SIB1 of the selected cell or reselected cell refers to the SIB1 received by the UE from the cell or the SIB1 broadcast by the cell. The current selected or reselected cell refers to the cell to which the UE has selected or reselected, i.e. the cell in which the UE is located (or camps) after performing the selection or reselection operation.

[0070] In the embodiments of the present disclosure, after starting the RRC connection resume for MBS multicast reception, the UE can perform the following operations:

[0071] A UE in RRC_INACTIVE, if configured to receive MBS multicast in RRC_INACTIVE, further if the RRC connection resume is triggered for MBS multicast reception upon reception of SIB1, start the RRC connection resume procedure and / or set the resumeCause to mt-Acess. The resumeCause is used to provide the resume cause for the RRC connection resume request as provided by the upper layers or RRC.

[0072] The purpose of the RRC connection resume procedure is mainly to resume a suspended RRC connection, including resuming SRBs, DRBs, multicast MRBs or performing RAN-based Notification Area, RNA, update, or to initiate RRC_INACTIVE small data transmission, SDT.

[0073] A UE receives an RRC release message from a base station, the RRC release message contains a multicastConfigInactive field, which indicates the multicast sessions or services that the UE can receive in the current serving cell when in RRC_INACTIVE, the current cell is the cell where the UE received the MBS multicast session when in RRC_CONNECTED. When the multicastConfigInactive field is included (i.e. its value is set to “setup”) in the received RRC release message, it indicates that the UE has been configured to receive MBS multicast in RRC_INACTIVE. However, in the case of CA, if the UE has not been configured with MBS multicast session when in RRC_CONNECTED, it is not possible to determine which cell is the current serving cell. The following embodiments solve this problem.

[0074] Embodiment 2

[0075] As shown in FIG. 2, at step 201, the UE receives an RRC release message from a base station.

[0076] In step 202, if the multicastConfigInactive field (i.e., the multicastConfigInactive field is set to "setup") is included in the RRC release message, further if the multicast PTM configuration is provided for the multicast session which is not indicated to stop detecting G-RNTI in the RRC release message (or if the multicast PTM configuration is provided for the multicast session in the RRC release message), and A1 or A2 is satisfied, the multicast PTM configuration and / or detecting multicast MCCH-RNTI (when multicast MCCH is provided) is applied. Wherein,

[0077] A1: The UE is configured with the MBS multicast session (i.e., the UE is configured with the MBS multicast session in RRC_CONNECTED or the UE is configured with the MBS multicast session before receiving the RRC message), and the cell selected by the UE is the cell of the MBS multicast session received by the UE in RRC connected state.

[0078] A2: The UE is not configured with the MBS multicast session (i.e., the UE is not configured with the MBS multicast session in RRC_CONNECTED or the UE is not configured with the MBS multicast session before receiving the RRC message), and the cell selected by the UE is the cell where the UE receives (i.e., the latest reception or previous reception) the RRC release message or is the primary cell PCell or is the PCell when the UE receives (i.e., the latest reception or previous reception) the RRC release message or is the primary cell PCell when the UE is in RRC_CONNECTED.

[0079] In embodiment 2, the multicastConfigInactive field can have the following B1-B3:

[0080] B1: The multicastConfigInactive field indicates the multicast session or service that the UE can receive in the serving cell when the UE is in RRC_INACTIVE, and if the UE is configured with the MBS multicast session in RRC connected state, the serving cell is the cell where the UE receives the MBS multicast session in RRC connected state, otherwise, the serving cell is the cell where the UE receives (i.e., the latest reception or previous reception) the RRC release message or is the primary cell PCell when the UE is in RRC_CONNECTED or is the primary cell PCell when the UE receives (i.e., the latest reception or previous reception) the RRC release message.

[0081] B2: The multicastConfigInactive field indicates the multicast session or service that the UE receives when in RRC_INACTIVE, and optionally also provides the corresponding configuration for the multicast session or service for the serving cell. Where the serving cell is the cell on which the UE receives the MBS multicast session when in RRC CONNECTED if the UE is configured with the MBS multicast session when in RRC CONNECTED, otherwise the serving cell is the cell on which the UE receives (i.e. last or previously received) the RRC release message or the primary cell PCell when the UE is in RRC CONNECTED or the primary cell PCell when the UE receives (i.e. last or previously received) the RRC release message.

[0082] B3: The multicastConfigInactive field indicates the multicast session or service that the UE receives when in RRC_INACTIVE, and optionally also provides the corresponding configuration for the multicast session or service. If there is a multicast session that is not indicated to stop detecting the G-RNTI, the UE in RRC INACTIVE receives the multicast session on the cell on which the UE receives the multicast session when the UE was previously in RRC CONNECTED; otherwise, the UE in RRC INACTIVE receives the multicast session or service on the cell on which the UE receives (i.e. last or previously received) the RRC release message or the primary cell PCell when the UE is in RRC CONNECTED or the primary cell PCell when the UE receives (i.e. last or previously received) the RRC release message.

[0083] The multicast PTM configuration in the present disclosure can refer to the MRB configuration of the multicast MBS session.

[0084] In the embodiments of the present disclosure, the UE being configured with the MBS multicast session when in RRC CONNECTED is that the UE is receiving or configured with the MBS multicast session when in RRC CONNECTED.

[0085] Optionally, in the embodiments of the present disclosure, the cell in which the UE receives the MBS multicast session in RRC_CONNECTED can be replaced by the cell in which the UE receives the MBS multicast session configured for RRC_INACTIVE reception in RRC_CONNECTED. If none of the MBS multicast sessions configured for RRC_INACTIVE reception is configured at the UE when the UE is in RRC_CONNECTED, it is also considered that the UE is not configured with the MBS multicast session in RRC_CONNECTED. The cell in which the UE receives the MBS multicast session in RRC_CONNECTED can also be replaced by the cell in which the UE receives the G-RNTI in RRC_CONNECTED or the cell in which the UE receives the G-RNTI of the MBS multicast session configured for RRC_INACTIVE reception in RRC_CONNECTED. In addition, if all the multicast sessions configured for the UE in RRC_CONNECTED are configured for PTP transmission or all the MBS multicast sessions configured for RRC_INACTIVE reception are configured for PTP transmission in RRC_CONNECTED, it is also considered that the UE is not configured with the MBS multicast session in RRC_CONNECTED.

[0086] The multicastConfigInactive field can include two fields, namely the inactivePTM-Config field and the inactiveMCCH-Config field. The inactivePTM-Config field indicates the PTM configuration of the MBS multicast received in RRC_INACTIVE in the serving cell, wherein the MBSMulticastConfiguration message is carried. The inactiveMCCH-Config field carries the system information SIB24.

[0087] For the UE configured to receive the MBS multicast service in RRC_INACTIVE, when the UE moves to a different cell providing the SIB24, the UE acquires the MBSMulticastConfiguration message from the multicast MCCH of the cell in the next repetition period. However, how the UE determines whether it has moved to a different cell is a problem to be solved. The following embodiments solve this problem.

[0088] Embodiment 3

[0089] For a UE configured to receive an MBS multicast service in RRC_INACTIVE, when the UE performs cell selection or cell reselection to select a new cell providing SIB24, the UE acquires an MBSMulticastConfiguration message on a multicast MCCH of the new cell in the next repetition period. Where the UE performs cell selection, the new cell is a cell different from the reference cell described in Embodiment 1 and its variants. Here, the above is not repeated.

[0090] In the present disclosure, the MBS multicast or multicast session or service is the MBS multicast session or service.

[0091] Unless otherwise specified, the embodiments performed by the UE or the base station in the present disclosure can be performed by the RRC entity in the UE or the base station or at the RRC layer. In the present disclosure, the fields, domains, and information elements are used interchangeably. In the embodiments of the present disclosure, if multiple operations are included, the embodiments obtained by changing the execution order of the operations are also within the scope of protection of the present disclosure, and when multiple parallel judgment conditions are included, the embodiments obtained by changing the order of the judgment conditions are also within the scope of protection of the present disclosure. In the embodiments of the present disclosure, “and”, “or”, “and / or”, “and”, and “and” in the conditions are used interchangeably, and the embodiments obtained are also within the scope of the present disclosure.

[0092] Next, a user device that can perform the method performed by the user device described in detail above in the present disclosure as an embodiment will be described using FIG. 3.

[0093] FIG. 3 is a block diagram showing a user device UE related to the present disclosure.

[0094] As shown in FIG. 3, the user device UE 400 includes a processor 401 and a memory 402. The processor 401 can include, for example, a microprocessor, a microcontroller, an embedded processor, or the like. The memory 402 can include, for example, a volatile memory (such as a random access memory (RAM)), a hard disk drive (HDD), a non-volatile memory (such as a flash memory), or other memory, or the like. The memory 402 stores program instructions thereon. The instructions, when executed by the processor 401, can perform the above-described method performed by the user device described in detail in the present disclosure.

[0095] The above has described in detail the method performed by the user device and the user device related to the present disclosure based on Embodiment 1 and the like, but the present disclosure is not limited to the method performed by the user device and the user device, and can be implemented in other ways as long as the spirit of the present disclosure can be achieved.

[0096] The method and the apparatus involved in the present disclosure have been described above in connection with preferred embodiments. Those skilled in the art can understand that the method shown above is only exemplary, and the embodiments described above can be combined with each other without contradiction. The method of the present disclosure is not limited to the steps and the order shown above.

[0097] In the embodiments of the present disclosure, in the case of containing multiple operations, the embodiments of the present disclosure exemplarily list the execution order of each operation, and the embodiments obtained by changing the execution order of each operation are also within the protection scope of the present disclosure. In addition, in the case of containing multiple judgment conditions, the embodiments obtained by changing the execution order of each judgment condition are also within the protection scope of the present disclosure. In addition, in the present disclosure, unless specifically stated, the meaning of the domain defined in one embodiment can also be applied to the corresponding domain involved in other embodiments. In addition, in the embodiments of the present disclosure, “if”, “when”, “if the”, “when the”, “in the case of”, “satisfy” or “satisfy the condition” can be replaced by “in the case of”. In the embodiments of the present disclosure, the embodiments obtained by replacing “and”, “and”, “and” in part or all of the conditions with “or” are also within the protection scope of the present disclosure; the embodiments obtained by replacing “or” in part or all of the conditions with “and” are also within the protection scope of the present disclosure.

[0098] In addition, the user equipment shown above can include more modules, for example, modules that can be developed or will be developed in the future, which can be used for base stations, MMEs, or UEs, and the like. The various identifiers shown above are only exemplary and not limited to the specific information elements as examples of these identifiers. Those skilled in the art can make many changes and modifications according to the teachings of the embodiments shown.

[0099] It should be understood that the above embodiments of the present disclosure can be realized by software, hardware or a combination of software and hardware. For example, various components inside the base station and the user equipment in the above embodiments can be realized by various devices, including but not limited to: analog circuit devices, digital circuit devices, digital signal processing (DSP) circuits, programmable processors, special integrated circuits (ASICs), field programmable gate arrays (FPGAs), programmable logic devices (CPLDs), and the like.

[0100] In addition, the computer executable instructions or programs running on the apparatus according to the present disclosure can be programs for making a computer realize the functions of the embodiments of the present disclosure by controlling a central processing unit (CPU). The programs or information processed by the programs can be temporarily stored in a volatile memory (such as a random access memory RAM), a hard disk drive (HDD), a non-volatile memory (such as a flash memory), or other memory systems.

[0101] Computer-executable instructions or programs for implementing the functions of the embodiments of the present application can be recorded on a computer-readable storage medium. The corresponding functions can be implemented by causing a computer system to read the programs recorded on the recording medium and execute the programs. The so-called "computer system" herein can be a computer system embedded in the device and can include an operating system or hardware such as a peripheral device. The "computer-readable storage medium" can be a semiconductor recording medium, an optical recording medium, a magnetic recording medium, a short-time dynamic storage program recording medium, or any other recording medium readable by a computer.

[0102] The various features or functional modules of the device used in the above-described embodiments can be implemented or executed by a circuit (e.g., a single-chip or multi-chip integrated circuit). The circuit designed to perform the functions described in the present specification can include a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, or any combination thereof. The general-purpose processor can be a microprocessor, but implementation is not limited thereto. The general-purpose processor can also be any existing processor, controller, microcontroller, or state machine. The above-described circuit can be a digital circuit, and also can be an analog circuit. If new integrated circuit technologies appear due to the advancement of semiconductor technologies, one or more embodiments of the present application can also be implemented using such new integrated circuit technologies.

[0103] Furthermore, the present application is not limited to the above-described embodiments. Although various examples of the embodiments have been described, the present application 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 devices, kitchen devices, cleaning devices, air conditioners, office devices, vending machines, and other home appliances.

[0104] As described above, the embodiments of the present application have been described in detail with reference to the accompanying drawings. However, the specific configuration is not limited to the above-described embodiments, and the present application includes any design modification without departing from the spirit of the present application. In addition, various modifications can be made to the present application within the scope of the claims, and embodiments obtained by appropriately combining the technical means invented in the different embodiments are also included in the technical scope of the present application. Furthermore, components described in the above-described embodiments having the same effect can be substituted for each other.

Claims

1. A method performed by a user equipment (UE) in an RRC_INACTIVE state, comprising: The UE receives SIB1 from the base station and stores the SIB1; In a case where the relevant information in the SIB1 is forwarded to the upper layer and the forwarded information does not result in the upper layer triggering message transmission, if the UE is configured to receive MBS multicast in RRC_INACTIVE, and further, if SIB24 is not scheduled in the SIB1 on the new cell after cell selection or reselection, initiating the RRC connection recovery procedure; The new cell after the cell selection or cell reselection is different from the cell in which the UE receives the MBS multicast session when the UE is in RRC_CONNECTED.

2. The method according to claim 1, wherein The information forwarded to the upper layer includes a cellIdentity field for clearly identifying a cell in a PLMN / SNPN and a trackingAreaCode field for indicating the tracking area code to which the cell indicated by the cellIdentity field belongs.

3. The method according to claim 1 or 2, wherein: The upper layer is the NAS layer.

4. A user equipment, comprising: processor; as well as a memory, wherein instructions are stored in the memory; When the instructions are executed by the processor, the user equipment is caused to execute the method according to any one of claims 1 to 3.

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