CN117678246A

CN117678246A - Method for processing multicast/broadcast service, user equipment and base station

Info

Publication number: CN117678246A
Application number: CN202180100622.XA
Authority: CN
Inventors: 张鑫; 生嘉
Original assignee: Huizhou TCL Cloud Internet Corp Technology Co Ltd
Current assignee: Huizhou TCL Cloud Internet Corp Technology Co Ltd
Priority date: 2021-07-15
Filing date: 2021-07-15
Publication date: 2024-03-08
Also published as: WO2023283896A1

Abstract

A method for processing multicast/broadcast service MBS can be executed in user equipment UE. The method comprises the following steps: receiving multicast/broadcast service MBS data transmitted through an MBS Transmission Channel (MTCH)/MBS Control Channel (MCCH), wherein the MTCH/MCCH is configured by a Multicast Radio Bearer (MRB) of a base station; determining whether the UE remains in a radio resource control, RRC, connected state when the multicast session has no ongoing data; determining whether a data inactivity timer is applicable to the MTCH/MCCH when the UE remains in an RRC connected state; setting the data inactivity timer to a value representing an infinite duration when the data inactivity timer is applicable to the MTCH/MCCH; and closing the data inactivity timer when the data inactivity timer is not applicable to the MTCH/MCCH. The DRBs and MRBs for transmitting and receiving MBS data can be maintained for a longer time even though there is no ongoing data.

Description

Method for processing multicast/broadcast service, user equipment and base station

Technical Field

The present invention relates to the field of communication systems, and more particularly, to a method of handling a multicast/broadcast service system.

Background

Wireless communication systems and networks have evolved into broadband and mobile systems. In a cellular wireless communication system, a User Equipment (UE) is connected to a Radio Access Network (RAN) through a radio link. The RAN includes a set of Base Stations (BS) and interfaces to a Core Network (CN). These base stations provide radio links with UEs located within the cell covered by the base stations, the core network provides overall network control, and the RAN and CN each perform their respective functions on the overall network. The third generation partnership project (3 GPP) has developed a Long Term Evolution (LTE) system, i.e., an evolved universal mobile telecommunications system terrestrially incorporated radio access network (E-UTRAN), for mobile access networks in which one or more macro cells are supported by base stations called enodebs or enbs (evolved nodebs). LTE is further evolving towards 5G or NR (new radio) systems, where one or more cells are supported by base stations called gnbs.

NR increases support for multicast and broadcast services. There are two transmission methods available for transmitting data packet streams of Multicast and Broadcast Services (MBS) over the air. One method is a point-to-multipoint (PTM) transmission method in which the RAN node transmits a single copy of MBS data packets over the air to a group of UEs. Another approach is the point-to-point (PTP) transmission method, wherein the RAN node transmits a single copy of the MBS data packet to each UE by radio.

RAN2 is developing two MBS delivery modes: delivery mode 1 (DM 1) and delivery mode 2DM2.DM1 is used for multicast session delivery, and is applicable to RRC connected UEs. The UE is provided with MBS configuration. DM1 may use point-to-point and point-to-multipoint transmissions and may utilize UL UE feedback, such as hybrid automatic repeat request (HARQ), when the UE is in a Radio Resource Control (RRC) connected state. DM2 is used for broadcast session delivery and is applicable to UEs in RRC connected state, RRC idle state and RRC inactive state.

RAN2 also defines two types of logical channels, namely an MBS Transport Channel (MTCH) and an MBS Control Channel (MCCH), for at least broadcast session transfer using DM2. The MBS transmission channel is also called a multicast transmission channel, and the MBS control channel is also called a multicast control channel. The MTCH is a point-to-multipoint downlink channel used to transmit traffic data from the network to the UE. The MCCH is a point-to-multipoint downlink channel for transmitting MBS control information from a network to a UE, and is applicable to one or more MTCHs.

The UE may be capable of receiving a multicast/broadcast service in a mixed mode or a broadcast mode. Using the mixed mode (i.e., DM 1), a multicast and broadcast service may be provided for UEs in a Radio Resource Control (RRC) connected state using MBS Radio Bearers (MRBs) or Data Radio Bearers (DRBs). Using the broadcast mode (i.e., DM 2), the multicast/broadcast service may be provided using the MRB of the UE in the RRC connected state, the RRC idle state, or the RRC inactive state.

Technical problem

MBS services can be received regardless of Radio Resource Control (RRC) state. However, upon receiving DM1, the UE needs to maintain an RRC connected state to handle the MBS service/multicast session, and when the multicast session has no ongoing data, the UE needs to maintain the RRC connected state, which is the first problem to be solved. Furthermore, when the UE may transition to the RRC idle/inactive state, the MBS service may need to set a different data inactivity timer value for each MAC entity. However, after the data inactivity timer adopts the set value, the set value will be applied by the whole MAC entity, which is the second problem to be solved.

Technical proposal

A first aspect of the present invention proposes a method for handling multicast/broadcast services MBS, the method being performed at a user equipment UE, the method comprising: receiving multicast/broadcast service MBS data transmitted through an MBS Transmission Channel (MTCH)/MBS Control Channel (MCCH), wherein the MTCH/MCCH is configured by a Multicast Radio Bearer (MRB) of a base station; determining whether the UE remains in a radio resource control, RRC, connected state when the multicast session has no ongoing data; determining whether a data inactivity timer is applicable to the MTCH/MCCH when the UE remains in an RRC connected state; setting the data inactivity timer to a value representing an infinite duration when the data inactivity timer is applicable to the MTCH/MCCH; and closing the data inactivity timer when the data inactivity timer is not applicable to the MTCH/MCCH.

A second aspect of the present invention provides a user equipment comprising: a memory storing instructions; and one or more processors coupled to operate with the memory, wherein the one or more processors execute the instructions to perform operations comprising: receiving multicast/broadcast service MBS data transmitted through an MBS Transmission Channel (MTCH)/MBS Control Channel (MCCH), wherein the MTCH/MCCH is configured by a Multicast Radio Bearer (MRB) of a base station; determining whether the UE remains in a radio resource control, RRC, connected state when the multicast session has no ongoing data; determining whether a data inactivity timer is applicable to the MTCH/MCCH when the UE remains in an RRC connected state; setting the data inactivity timer to a value representing an infinite duration when the data inactivity timer is applicable to the MTCH/MCCH; and closing the data inactivity timer when the data inactivity timer is not applicable to the MTCH/MCCH.

A third aspect of the present invention provides a method of processing a multicast/broadcast service MBS, the method being performed in a base station, the method comprising: transmitting multicast/broadcast service MBS data to User Equipment (UE) through an MBS transmission channel (MTCH/MBS Control Channel (MCCH), wherein the MTCH/MCCH is configured by a Multicast Radio Bearer (MRB) of the base station; transmitting a configuration to the UE for the UE to perform steps comprising: determining whether the UE remains in a radio resource control, RRC, connected state when the multicast session has no ongoing data; determining whether a data inactivity timer is applicable to the MTCH/MCCH when the UE remains in an RRC connected state; setting the data inactivity timer to a value representing an infinite duration when the data inactivity timer is applicable to the MTCH/MCCH; and closing the data inactivity timer when the data inactivity timer is not applicable to the MTCH/MCCH.

A fourth aspect of the present invention provides a base station, comprising: a memory storing instructions; and one or more processors coupled to operate with the memory, wherein the one or more processors execute the instructions to perform operations comprising: transmitting multicast/broadcast service MBS data to User Equipment (UE) through an MBS transmission channel (MTCH/MBS Control Channel (MCCH), wherein the MTCH/MCCH is configured by a Multicast Radio Bearer (MRB) of the base station; transmitting a configuration to the UE for the UE to perform steps comprising: determining whether the UE remains in a radio resource control, RRC, connected state when the multicast session has no ongoing data; determining whether a data inactivity timer is applicable to the MTCH/MCCH when the UE remains in an RRC connected state; setting the data inactivity timer to a value representing an infinite duration when the data inactivity timer is applicable to the MTCH/MCCH; and closing the data inactivity timer when the data inactivity timer is not applicable to the MTCH/MCCH.

The method of the present invention may be implemented in a chip. The chip may include a processor configured to invoke and run a computer program stored in a memory to cause a device on which the chip is installed to perform the method of the invention.

The invention may program and store computer executable instructions in a non-transitory computer readable medium. The non-transitory computer readable medium, when loaded into a computer, instructs the processor of the computer to perform the methods disclosed herein. The non-transitory computer readable medium may include at least one of the following readable media: hard disks, CD-ROMs, optical storage devices, magnetic storage devices, read-only memory, programmable read-only memory, erasable programmable read-only memory, EPROM, electrically erasable programmable read-only memory, and flash memory.

The disclosed methods may be programmed as a computer program product that causes a computer to perform the disclosed methods.

The disclosed methods may be programmed as a computer program that causes a computer to perform the disclosed methods.

Advantageous effects

The embodiment of the invention provides a method, a base station and user equipment for processing multicast/broadcast service MBS. Upon receiving DM1, the UE can maintain the RRC connected state to handle the MBS service/multicast session and allow the RRC connected state to be maintained when the multicast session has no ongoing data. The method is by setting the data inactivity timer to a value indicating an infinite duration or closing the data inactivity timer. When the multicast session has no ongoing data, the UE may save resources (e.g., memory resources, processing resources, or battery power, etc.) by maintaining the RRC connected state and receive the multicast session using the maintained MRB, thereby reducing latency and saving signaling overhead associated with establishing the MRB. In addition, in case that the UE can transition to the idle/inactive mode when no data is in progress, the present invention suggests to replace the value of the data inactivity timer corresponding to DRB with the value of the data inactivity timer corresponding to MRB or to select the larger value of the data inactivity timers of DRB and MRB as the value of the data inactivity timer of DRB and MRB. Therefore, DRBs and MRBs for transmitting and receiving MBS data can be maintained for a longer time even though there is no ongoing data.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic diagram of a communication system according to an embodiment of the invention.

Fig. 2 illustrates a downlink layer 2 architecture for a multicast session.

Fig. 3 illustrates a downlink layer 2 architecture for a broadcast session.

Fig. 4 is a flowchart illustrating a MBS method according to an embodiment of the present invention.

FIG. 5 is a flowchart illustrating a method for handling MBS according to another embodiment of the invention.

Fig. 6 is a block diagram of an example system for wireless communication according to an embodiment of the present invention.

Detailed Description

The embodiments of the present invention describe in detail technical matters, structural features, achieving objects and effects with reference to the accompanying drawings as follows. In particular, the terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure.

Referring to fig. 1, the communication system includes a User Equipment (UE) 10, a Base Station (BS) 200, and a network entity apparatus 30. The connections between the devices and the device components are shown as lines and arrows in the figures. The UE 10 may include a processor 11, a memory 12, and a transceiver 13. The base station 200 may include a processor 201, a memory 202, and a transceiver 203. The network entity device 300 may include a processor 301, a memory 302, and a transceiver 303. Each processor 11, 201, and 301, when executed, may implement the functions, processes, and/or methods provided by the embodiments. The radio interface protocol layer may be implemented in the processor 11, 201, 301. Various programs and information may be stored in each memory 12, 202, and 302 to coordinate the operation of the connected processors. Each transceiver 13, 203, 303 is coupled to a processor for transmitting and/or receiving radio signals or wired signals. The functions carried by the base station 200 include inter-cell radio resource management (MME), radio Bearer (RB) control, connection mobility control, radio admission control, measurement configuration/configuration, dynamic resource allocation (scheduler). Base station 200 may be referred to by other terminology such as an evolved NodeB (eNB), a gNB, an Access Point (AP), or one of the other types of radio nodes. In 3GPP, the term "cell" can refer to the area covered by a base station or a base station subsystem serving the coverage area.

The processors 11, 201, 301 may include Application Specific Integrated Circuits (ASICs), other chipsets, logic circuits, and/or data processing devices. The memory 12, 202, 302 may include Read Only Memory (ROM), random Access Memory (RAM), flash memory, memory cards, storage media, and/or other storage devices. The transceivers 13, 203, and 303 may include baseband circuitry and Radio Frequency (RF) circuitry to process radio frequency signals. When the embodiments are implemented in software, the techniques described herein may be implemented with modules, procedures, functions, entities, etc. that perform the functions described herein. Modules may be stored in memory and executed by a processor. The memory may be implemented within the processor or external to the processor, and various means known in the art can be coupled to the processor.

The network entity device 300 may be a node in the CN. The CN may include a LTECN or 5G core network (5 GC) including a User Plane Function (UPF), a Session Management Function (SMF), a mobility management function (AMF), a Unified Data Management (UDM), a Policy Control Function (PCF), a Control Plane (CP)/User Plane (UP) split (CUPS), an authentication server (AUSF), a Network Slice Selection Function (NSSF), and a network opening function (NEF).

The UE 10 may transition between an RRC connected state, an RRC idle state, and an RRC inactive state. In the RRC inactive state, the UE 10 maintains the RRC connected state while reducing signaling and power consumption. In the RRC inactive state, the UE 10 may transition to the RRC connected state through RRC connection restoration (also referred to as RRC restoration), or may transition to the RRC idle state through RRC connection release or due to a connection failure. In the RRC connected state and the RRC inactive state, the UE 10 has registered with and is connected to the core network. In the RRC idle state, the UE 10 will de-register from the core network.

When the base station 200 detects that the UE 10 has no traffic to send and receive for a defined period of time, it is typically dependent on the state of a data inactivity timer (also called datainactivity timer in the LTE and NR protocol specifications of 3 GPP) 204 (10 seconds, 20 seconds, etc.), which is defined in the base station 200 and configurable, and the base station 200 may then initiate an RRC procedure accordingly, transitioning the UE 10 from a Radio Resource Control (RRC) connected state to an RRC inactive state or an RRC idle state. If the UE 10 is not active for a short period of time, the UE 10 may suspend its session by entering an RRC inactive state and after a period of time may revert to an RRC connected state to resume its session. In the RRC idle state, the UE 10 has no connection with the network entity device 300 and all the contexts related to the UE 10 are deleted from the E-UTRAN. When the UE 10 is in an idle state using the data inactivity timer, existing connections such as Signal Radio Bearers (SRBs), multicast and broadcast service radio bearers (MRBs), and Data Radio Bearers (DRBs) are removed. The S1-MME control plane and S1-U user plane connections are also removed.

Please refer to fig. 2 and 3. Fig. 2 illustrates a downlink layer 2 architecture for a multicast session. Fig. 3 illustrates a downlink layer 2 architecture for a broadcast session. Target applications for Multicast and Broadcast Services (MBS) include radio broadcasting, real-time streaming video services, file transfer, and emergency alerts. Multicast and broadcast content is transmitted through a geographic area called an MBS zone. An MBS zone is a set of one or more base stations that transmit the same content. Each base station capable of providing MBS services may belong to one or more MBS zones. Each MBS zone has a unique zone identifier identification. The base station 200 may provide multicast and broadcast services corresponding to different MBS zones. The MBS data burst may be transmitted in the form of a plurality of sub-packets, which may be transmitted at different time intervals to allow the UE 10 to combine the sub-packets without transmitting acknowledgements. The UEs 10 in the MBS zone (including the UEs 10a and 10 b) are assigned a common multicast station identifier. MBS PDUs are transmitted by all base stations within the same MBS zone. MBS services may be provided over dedicated radio frequency carriers or hybrid unicast, multicast and broadcast radio frequency carriers. The UE 10 may receive MBS contents within the MBS zone in a connected state or an idle state.

The base station 200 may transmit the MRB/DRB configuration of the MRB/DRB to the UE 10 in a Radio Link Control (RLC) Acknowledged Mode (AM). The term MRB/DRB is used herein to refer to MRB, DRB or both. In RLC AM, acknowledgement (ACK) or Negative Acknowledgement (NACK) feedback and retransmission may be used to support reliable transmission of multicast/broadcast traffic. ACK or NACK (referred to as ACK/NACK) feedback may be transmitted by the UE 10 in the RLC status report. The base station 200 may send the MRB/DRB configuration in a configuration message, e.g., an RRC message. The base station 200 and the UE 10 may establish an MRB/DRB based on the MRB/DRB configuration. The MRB configuration may indicate an MBS Control Channel (MCCH) for transmitting the multicast/broadcast control message. The MRB configuration may also indicate an MBS Transport Channel (MTCH) for transmitting multicast/broadcast data. The DRB configuration may indicate a Dedicated Transport Channel (DTCH) for transmitting multicast/broadcast data or unicast data. The DRB configuration may indicate a Dedicated Control Channel (DCCH) for transmitting a multicast/broadcast control message or a unicast control message. For example, the MRB/DRB configuration may indicate resources (e.g., time domain resources, frequency domain resources, or spatial domain resources) allocated to the MCCH and MTCH. The MRB configuration may indicate a group radio network temporary identifier (G-RNTI) associated with the MRB. The G-RNTI may be used for transmission and reception of communications at the MRB. In some embodiments, different multicast/broadcast subscriptions may be associated with different G-RNTIs.

The MRB configuration may indicate a retransmission configuration of multicast/broadcast traffic transmitted over the MRB. For example, the MRB configuration may indicate that the retransmission is a unicast retransmission (a cell radio network temporary identifier (C-RNTI) may be used in a similar manner as the G-RNTI), a multicast/broadcast retransmission (a G-RNTI may be used, as described above) to enable switching between unicast and multicast/broadcast. The retransmission configuration may indicate one or more resources for retransmission.

In RRC connected mode, the base station 200 may transmit multicast/broadcast control information to the UE 10 through the MRB (e.g., on the MCCH). The base station 200 may transmit MBS data to the UE 10 through the MRB (e.g., on the MTCH).

After configuring the MRB, the UE 10 may transition from the RRC connected state to an RRC idle state or an RRC inactive state, e.g., exit the connected state and enter one of the idle state or the inactive state. The UE 10 may transition from the RRC connected state to the RRC idle state through RRC connection release (RRC connection release). Alternatively, the UE 10 may suspend (RRC connection suspension) through the RRC connection to transition from the RRC connected state to the RRC inactive state. When a connection between the UE 10 and the base station 200 is established (e.g., by an RRC connection establishment procedure), the UE 10 may transition from an RRC idle state to an RRC connected state.

The MRB configuration may indicate an idle/inactive state configuration of the MRB. The term idle/inactive state is used herein to refer to an RRC idle state and/or an RRC inactive state. The MAC of the UE 10 may be configured by the UE RRC with the data inactivity monitoring function when the UE 10 is in the RRC connected state. The UE RRC may control data inactivity operations by configuring the data inactivity timer 204. The data inactivity timer may be used to control data inactivity operations. When configuring the data inactivity timer 204, if the UE 10 receives a MAC Service Data Unit (SDU) of a DTCH logical channel, DCCH logical channel, or CCCH logical channel, the UE 10 may start or restart the data inactivity timer 204. Alternatively, if the UE 10 receives a MAC SDU transmitted by a DTCH logical channel or DCCH logical channel, the UE 10 may start or restart the data inactivity timer 204. If the data inactivity timer 204 expires, the UE 10 may indicate to the upper layer the expiration of the data inactivity timer 204. Specifically, upon expiration of the data inactivity timer 204, the UE 10 may perform an operation upon exiting the RRC connected state, the release being due to "RRC connection failure", and the UE 10 may exit the RRC connected state and enter the RRC idle state.

Referring to fig. 1 and 4, fig. 4 shows a method of MBS processing according to an embodiment of the present invention, the method includes steps 302-328.

Step 302: multicast/broadcast service (MBS) data configured according to an MBS Radio Bearer (MRB) configuration of the base station 200 is received through an MBS Transport Channel (MTCH)/MBS Control Channel (MCCH). In the present invention, MBS data is focused on multicast data that can be transmitted in an RRC connected state but not in an RRC idle/inactive state.

Step 304: it is determined whether the UE 10 is forcibly required to maintain the RRC connected state when the multicast session has no ongoing data.

Step 306: when the UE 10 is required to maintain the RRC connected state, it is determined whether the data inactivity timer 204 is applicable to the MTCH/MCCH.

Step 308: when the data inactivity timer 204 is applicable to the MTCH/MCCH, the data inactivity timer is set to a value indicating an infinite duration.

Step 310: when the data inactivity timer 204 is not applicable to the MTCH/MCCH, it is determined whether the UE 10 receives Data Radio Bearer (DRB) data before receiving MBS data.

Step 312: when the UE 10 receives DRB data before receiving MBS data, it is determined whether to configure the data inactivity timer 204 in the DRB configuration procedure.

Step 314: when the UE 10 does not receive DRB data before receiving MBS data, the data inactivity timer 204 is closed.

Step 316: when the UE 10 needs to receive DRB data, the data inactivity timer 204 is closed during DRB configuration.

Step 318: when the data inactivity timer 204 has not been configured during DRB configuration, the data inactivity timer 204 is closed.

Step 320: when the data inactivity timer 204 is configured during DRB configuration, the data inactivity timer 204 is stopped during MRB configuration.

Step 322: when the UE 10 is not required to maintain the RRC connected state, a data inactivity timer 204 is enabled for the MTCH/MCCH.

Step 324: it is determined whether the Data Radio Bearer (DRB) and the MBS Radio Bearer (MRB) share the value of the data inactivity timer 204.

Step 326: when the DRB and the MRB share the value of the data inactivity timer, the value of the data inactivity timer 204 of the DRB is replaced with the value of the data inactivity timer 204 of the MRB, or the larger value of the data inactivity timer 204 corresponding to the DRB and the value of the inactivity timer 204 corresponding to the MRB is selected as the value of the inactivity timer 204 corresponding to the DRB and the MRB.

Step 328: when the DRB and the MRB do not share the value of the data inactivity timer 204, the values of the data inactivity timers 204 of the DRB and the MRB are set to the same value or different values.

According to the present disclosure, the method provides a mechanism for the following two scenarios. Steps 304-320 are for a scenario where the UE needs to maintain a connected mode when the multicast session has no data, and steps 322-328 are for a scenario where the UE may transition to an idle/inactive mode when no data is in progress.

When transmission of multicast/broadcast service (MBS) data is through an MBS Transmission Channel (MTCH)/MBS Control Channel (MCCH) configured from the base station 200, the UE 10 determines whether the UE 10 is forced to maintain an RRC connected state when a multicast session has no ongoing data. If the UE 10 is forced to maintain the RRC connected state, the UE 10 determines whether the data inactivity timer 204 is applicable to an MBS Transmission Channel (MTCH)/MBS Control Channel (MCCH). If the data inactivity timer 204 is applicable to the MTCH/MCCH, the data inactivity timer 204 is set to a value that indicates an infinite duration. As shown in table 1, the data inactivity timer 204 may be preset to one of predetermined values, e.g., s1, s2, s180. Once the data inactivity timer 204 is set to a value that indicates an infinite period of time, expiration of the data inactivity timer 204 will not occur. Thus, the UE 10 can always maintain the RRC connected state even though the UE 10 does not have ongoing multicast session data.

TABLE 1

The data inactivity timer may be defined as shown in table 1. For example, the value s1 corresponds to 1 second, s2 corresponds to 2 seconds, and so on.

In step 314, when the UE 10 receives MBS data before and without receiving DRB data, the data inactivity timer 204 is closed during MRB configuration or in response to closing information contained in RRC signaling, medium Access Control (MAC) Control Element (CE), or Downlink Control Information (DCI) transmitted by the base station 200. Closing the data inactivity timer 204 may be accomplished by not configuring the data inactivity timer 204. Since the data inactivity timer 204 is not configured, the data inactivity timer 204 is not triggered, so the UE 10 may remain in the RRC connected state even if there is no ongoing data for the multicast session.

In step 312, when the UE 10 receives DRB data before receiving MBS data, the UE 10 determines whether to configure the data inactivity timer 204 in the DRB configuration procedure. When the data inactivity timer 204 is not configured during DRB configuration, the data inactivity timer 204 is closed during MRB configuration or in response to closing information contained in RRC signaling, MAC CE, or DCI transmitted by the base station 200. Closing the data inactivity timer 204 may be accomplished by not configuring the data inactivity timer 204. Since the data inactivity timer 204 is not configured, the data inactivity timer 204 is not triggered, so the UE 10 may remain in the RRC connected state even if there is no ongoing data for the multicast session.

In step 320, the data inactivity timer 204 is stopped when the data inactivity timer 204 is configured during DRB configuration, during MRB configuration, or in response to a shutdown message. Wherein the shutdown information is included in RRC signaling, MAC CE, or DCI transmitted by the base station 200. Since the data inactivity timer 204 is not configured during MRB configuration, the data inactivity timer 204 is not triggered, so the UE 10 may remain RRC connected even if no ongoing data is used for the multicast session.

Referring to FIG. 5, a flowchart of a method for processing MBS according to another embodiment of the invention is shown. In step 330, even if the UE 10 is required to remain in the RRC connected state (step 304), the UE 10 may enter an RRC idle/inactive state in response to some predetermined condition, such as whether the power value of the UE 10 is below a threshold. According to some embodiments, when the power value of the UE 10 is below a threshold (e.g., 20% of battery power), the UE 10 may be triggered to enter an RRC idle/inactive state. The UE 10 may automatically transition from the RRC connected state to the RRC idle/inactive state and send a message to the base station 200 that the UE 10 has entered the RRC idle/inactive state. In another embodiment, when the power value of the UE 10 is below the threshold, the UE 10 sends a request to the base station 200 to enter the RRC idle/inactive state. Then, the base station 200 issues a command to enter the RRC idle/inactive state to the UE 10, causing the UE 10 to transition from the RRC connected state to the RRC idle/inactive state in response to the command to enter the RRC idle/inactive state.

The present invention also proposes another solution for the scenario where the UE can transition to RRC idle/inactive mode when no data is in progress. In step 322, the data inactivity timer 204 for the MTCH/MCCH will be enabled when the UE 10 is not required to remain in the RRC connected state. The UE 10 then determines whether the value of the data inactivity timer 204 is shared by the Data Radio Bearer (DRB) and the multicast/broadcast radio bearer (MRB).

When the DRB and the MRB do not share the value of the data inactivity timer 204, the value of the data inactivity timer 204 corresponding to the DRB and the value of the data inactivity timer 204 corresponding to the MRB may be set to different values, for example, as follows:

DataInactivityTimer-DRB：：＝ENUMERATED{s1，s2，s3，s5，s7，s10，s15，s20，s40，s50，s60，s80，s100，s120，s150，s180}

DataInactivityTimer-MRB：：＝ENUMERATED{s360，s720}

in another embodiment, when the value of the data inactivity timer 204 is not shared by the DRB and the MRB, the value of the data inactivity timer 204 corresponding to the DRB and the value of the data inactivity timer 204 corresponding to the MRB may take the same value or otherwise be set to another same value, for example, as shown in the following figure:

DataInactivityTimer-MRB：：＝ENUMERATED{s150，s180，s360，s720}

in step 328, when the DRB and the MRB share the value of the data inactivity timer, the value of the data inactivity timer 204 of the DRB is replaced by the value of the data inactivity timer 204 of the MRB. In this embodiment, the UE 10 may decide that the value of the data inactivity timer 204 of the MRB has a higher priority, replacing the value of the data inactivity timer 204 of the DRB with the value of the data inactivity timer 204 of the MRB. For example, if the value of the data inactivity timer 204 of the MRB is s150 (150 seconds) and the value of the data inactivity timer 204 of the DRB is s180 (180 seconds), the UE 10 replaces the value of the data inactivity timer 204 of the DRB from "s180" to "s150".

In another embodiment, when the value of the data inactivity timer is shared by the DRB and the MRB, the greater value of the values of the data inactivity timer 204 corresponding to the DRB and the data inactivity timer 204 corresponding to the MRB is selected as the value shared by the inactivity timers 204 of the DRB and the MRB. For example, if the value of the data inactivity timer 204 of the MRB is s150 (150 seconds) and the value of the data inactivity timer 204 of the DRB is s180 (180 seconds), the UE 10 determines that the value of the data inactivity timer 204 of the DRB (s 180) is greater than the value of the data inactivity timer 204 of the MRB (s 150). Thus, the UE 10 replaces the value of the data inactivity timer 204 of the MRB from "s150" to "s180".

For the case where the UE 10 may transition to idle/inactive mode when no data is in progress, the present invention suggests replacing the value of the data inactivity timer of DRB with the value of the data inactivity timer of MRB or selecting the larger value of the data inactivity timers of DRB and MRB as the value of the inactivity timers of DRB and MRB. Therefore, DRBs and MRBs for transmitting and receiving MBS data can be maintained for a longer time even though there is no ongoing data.

Fig. 6 is a block diagram of a system 700 for wireless communication according to an embodiment of the present invention. The present embodiments may be implemented into a system using any suitably configured hardware and/or software. Fig. 5 illustrates a system 700 including Radio Frequency (RF) circuitry 710, baseband circuitry 720, processing unit 730, memory/storage unit 740, display 750, camera 760, sensor 770, and input/output (I/O) interface 780, coupled to one another as shown.

The processing unit 730 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. Processors may include any combination of general-purpose processors and special-purpose processors, such as graphics processors and application processors. The processor may be coupled with the storage/memory and configured to execute instructions stored in the storage/memory to activate various applications and/or operating systems running on the system. The radio frequency circuitry 710, baseband circuitry 720, processing unit 730, memory/storage 740, display 750, camera 760, sensor 770, and I/O interface 780 are existing components in system 700 such as, but not limited to, notebook computing devices, tablet computing devices, netbooks, ultrabooks, smartphones, and the like. Furthermore, instructions as a software product may be stored in a readable storage medium of a computer. The software product in the computer is stored in a storage medium including a plurality of commands for a computing device (e.g., a personal computer, a server, or a network device) to execute all or part of the steps disclosed by the embodiments of the present invention. The storage medium includes a USB disk, a removable hard disk, a Read Only Memory (ROM), a Random Access Memory (RAM), a floppy disk, or other medium capable of storing program code.

Embodiments of the present invention are a combination of techniques/procedures that may be employed in the 3GPP specifications to create the end product. The embodiment of the invention provides a method, a base station and user equipment for processing multicast/broadcast service MBS. Upon receiving DM1, the UE can maintain the RRC connected state to handle the MBS service/multicast session and allow the RRC connected state to be maintained when the multicast session has no ongoing data. The method is by setting the data inactivity timer to a value indicating an infinite duration or closing the data inactivity timer. When the multicast session has no ongoing data, the UE may save resources (e.g., memory resources, processing resources, or battery power, etc.) by maintaining the RRC connected state and receive the multicast session using the maintained MRB, thereby reducing latency and saving signaling overhead associated with establishing the MRB. In addition, in case that the UE can transition to the idle/inactive mode when no data is in progress, the present invention suggests to replace the value of the data inactivity timer corresponding to DRB with the value of the data inactivity timer corresponding to MRB or to select the larger value of the data inactivity timers of DRB and MRB as the value of the data inactivity timer of DRB and MRB. Therefore, DRBs and MRBs for transmitting and receiving MBS data can be maintained for a longer time even though there is no ongoing data.

While the embodiments of the invention have been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but is intended to cover various arrangements included within the scope of the appended claims without departing from the broadest interpretation of the claims.

Claims

1. A method of handling multicast/broadcast service, MBS, performed at a user equipment, UE, the method comprising:

receiving multicast/broadcast service MBS data transmitted through an MBS Transmission Channel (MTCH)/MBS Control Channel (MCCH), wherein the MTCH/MCCH is configured by a Multicast Radio Bearer (MRB) of a base station;

determining whether the UE remains in a radio resource control, RRC, connected state when the multicast session has no ongoing data;

determining whether a data inactivity timer is applicable to the MTCH/MCCH when the UE remains in an RRC connected state;

setting the data inactivity timer to a value representing an infinite duration when the data inactivity timer is applicable to the MTCH/MCCH; and

and closing the data inactivity timer when the data inactivity timer is not applicable to the MTCH/MCCH.

2. The method according to claim 1, characterized in that it further comprises:

When the data inactivity timer is not applicable to the MTCH/MCCH, determining whether the UE receives data radio bearer DRB data before receiving the MBS data.

3. The method according to claim 2, characterized in that it further comprises:

when the UE receives the MBS data and the DRB data before receiving the MBS data, judging whether the data inactivity timer is configured in a DRB configuration process;

stopping the data inactivity timer when the data inactivity timer is configured in the DRB configuration process; and

and closing the data inactivity timer when the data inactivity timer is not configured in the DRB configuration process.

4. A method according to claim 3, wherein the stop data inactivity timer comprises:

stopping the data inactivity timer during the MRB configuration or when responding to stopping information contained in RRC signaling, medium access control MAC control element CE, or downlink control information DCI; and

the close data inactivity timer comprises:

the data inactivity timer is closed during the MRB configuration or when a closing information is responded, wherein the closing information is included in the RRC signaling, the MAC CE, or the DCI.

5. The method according to claim 2, characterized in that it further comprises:

and closing the data inactivity timer when the UE receives the MBS data before receiving the DRB data.

6. The method of claim 5, wherein the closing a data inactivity timer comprises:

7. The method according to claim 5, further comprising:

the data inactivity timer is closed during the DRB configuration or when responding to closing information, wherein the closing information is contained in the RRC signaling, the MAC CE, or the DCI, when the UE receives the DRB data before receiving the MBS data.

8. The method of claim 1, wherein after the UE remains in the RRC connected state, the method further comprises:

when a condition is responded, the UE is triggered to enter an RRC idle/inactive state.

9. The method of claim 8, wherein upon triggering the UE to enter the RRC idle/inactive state, the method further comprises:

A message is sent to the base station to indicate that the UE has entered the RRC idle/inactive state.

10. The method of claim 8, wherein the triggering the UE to enter the RRC idle/inactive state comprises:

transmitting a request to enter the RRC idle/inactive state to the base station; and

entering the RRC idle/inactive state in response to a command sent by the base station to enter the RRC idle/inactive state.

11. The method of claim 8, wherein the condition comprises determining whether a power value of the UE is below a threshold.

12. The method as recited in claim 1, further comprising:

and when the UE does not maintain the RRC connection state, enabling the data inactivity timer applicable to the MTCH/MCCH.

13. The method as recited in claim 11, further comprising:

it is determined whether the data radio bearer DRB and the MBS radio bearer MRB share the value of the data inactivity timer.

14. The method as recited in claim 13, further comprising:

and when the DRB and the MRB share the value of the data inactivity timer, replacing the value of the data inactivity timer corresponding to the DRB with the value of the data inactivity timer corresponding to the MRB.

15. The method as recited in claim 13, further comprising:

when the DRB and the MRB share the value of the data inactivity timer, a larger value of the data inactivity timer is selected as the value of the inactivity timer for the DRB and the MRB.

16. The method as recited in claim 13, further comprising:

and when the DRB and the MRB do not share the value of the data inactivity timer, setting the value of the data inactivity timer corresponding to the DRB and the value of the data inactivity timer corresponding to the MRB to be the same value or different values.

17. A user equipment, comprising:

a memory storing instructions; and

one or more processors coupled to operate with the memory, wherein one or more of the processors execute the instructions to perform operations comprising:

18. The user equipment of claim 17, further comprising:

19. The user equipment of claim 18, further comprising:

20. The user equipment of claim 19, wherein the stop data inactivity timer comprises:

the close data inactivity timer comprises:

21. The user equipment of claim 18, further comprising:

22. The user equipment of claim 21, wherein the closing the data inactivity timer comprises:

23. The user equipment of claim 21, further comprising:

24. The user equipment of claim 17, wherein after the UE remains in an RRC connected state, the operations further comprise:

25. The user equipment of claim 23, wherein upon triggering the UE to enter the RRC idle/inactive state, the operations further comprise:

26. The user equipment of claim 23, wherein the triggering the UE to enter the RRC idle/inactive state comprises:

27. The user equipment of claim 23, wherein the condition comprises determining whether a power value of the UE is below a threshold.

28. The user device of claim 17, wherein the operations further comprise:

29. The user device of claim 27, wherein the operations further comprise:

30. The user device of claim 28, wherein the operations further comprise:

31. The user device of claim 28, wherein the operations further comprise:

32. The user device of claim 28, wherein the operations further comprise:

33. A method of processing a multicast/broadcast service MBS, the method being performed in a base station, the method comprising:

transmitting multicast/broadcast service MBS data to User Equipment (UE) through an MBS transmission channel (MTCH/MBS Control Channel (MCCH), wherein the MTCH/MCCH is configured by a Multicast Radio Bearer (MRB) of the base station;

transmitting a configuration to the UE for the UE to perform steps comprising:

34. The method of claim 32, further comprising:

35. The method as recited in claim 33, further comprising:

36. The method as recited in claim 34, further comprising:

transmitting MRB configuration or stop/close information to the UE, wherein the stop/close information is contained in RRC signaling, medium access control MAC control element CE, or downlink control information DCI;

wherein said stopping said data inactivity timer comprises:

stopping the data inactivity timer during the MRB configuration process or when responding to a stop message; and

The closing the data inactivity timer comprises:

the data inactivity timer is closed during the MRB configuration process or when responsive to a closing information.

37. The method as recited in claim 33, further comprising:

38. The method as recited in claim 36, further comprising:

transmitting MRB configuration or shutdown information to the UE, wherein the shutdown information is contained in RRC signaling, medium access control MAC control element CE, or downlink control information DCI;

wherein the close data inactivity timer comprises:

39. The method of claim 36, further comprising:

transmitting DRB configuration or shutdown information to the UE, wherein the shutdown information is contained in RRC signaling, medium access control, MAC, control element, CE, or downlink control information, DCI;

wherein the close data inactivity timer comprises:

the data inactivity timer is closed during the DRB configuration process or when responding to a closure message.

40. The method of claim 32, wherein after the UE maintains the RRC connected state, the method further comprises:

when the power value of the UE is below a threshold, a message is received from the UE to indicate that the UE has entered the RRC idle/inactive state.

41. The method as recited in claim 32, further comprising:

receiving a request to enter the RRC idle/inactive state from the UE when the power value of the UE is below a threshold; and

transmitting a command to enter the RRC idle/inactive state to the UE.

42. The method as recited in claim 32, further comprising:

43. The method as recited in claim 41, further comprising:

44. The method as recited in claim 42, further comprising:

45. The method of claim 43, further comprising:

46. The method as recited in claim 44, further comprising:

47. A base station, comprising:

a memory for storing instructions;

a transceiver operatively coupled to the memory, wherein one or more of the processors perform the method of any of claims 32 to 45.

48. A chip, comprising:

a processor configured to invoke and run a computer program stored in a memory to cause a device on which the chip is installed to perform the method of any of claims 1 to 16.

49. A computer readable storage medium in which a computer program is stored, wherein the computer program causes a computer to perform the method of any one of claims 1 to 16.

50. A computer program product comprising a computer program, wherein the computer program causes a computer to perform the method of any one of claims 1 to 16.