WO2023283896A1

WO2023283896A1 - Method for processing multicast/broadcast service, user equipment, and base station

Info

Publication number: WO2023283896A1
Application number: PCT/CN2021/106590
Authority: WO
Inventors: Xin Zhang; Jia SHENG
Original assignee: Huizhou Tcl Cloud Internet Corporation Technology Co.Ltd
Priority date: 2021-07-15
Filing date: 2021-07-15
Publication date: 2023-01-19
Also published as: CN117678246A

Abstract

A method for processing multicast/broadcast service (MBS) executable in a user equipment includes: receiving MBS data over MTCH/MCCH that are configured by a MRB configuration from a base station; determining whether the user equipment (UE) is mandated to stay in RRC connected state when there is no data ongoing for multicast session; when the UE is mandated to stay in the RRC connected state, determining whether a data inactivity timer is applicable to MTCH/MCCH; when the data inactivity timer is applicable to the MTCH/MCCH, setting the data inactivity timer to a value indicative of an infinite duration; and when the data inactivity timer is not applicable to the MTCH/MCCH, disabling the data inactivity timer during MRB configuration procedure. The DRB and the MRB for transmitting and receiving MBS data can be maintained for a longer time period even if no data ongoing.

Description

Method for Processing Multicast/Broadcast Service, User Equipment, and Base Station

Technical Field

The present disclosure relates to the field of communication systems, and more particularly, to a method of the broadcast/multicast service (MBS) system.

Background Art

Wireless communication systems and networks have developed towards being a broadband and mobile system. In cellular wireless communication systems, user equipment (UE) is connected by a wireless link to a radio access network (RAN) . The RAN comprises a set of base stations (BSs) which provide wireless links to the UEs located in cells covered by the base station, and an interface to a core network (CN) which provides overall network control. As will be appreciated the RAN and CN each conduct respective functions in relation to the overall network. The 3rd Generation Partnership Project (3GPP) has developed the so-called Long Term Evolution (LTE) system, namely, an Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, (E-UTRAN) , for a mobile access network where one or more macro-cells are supported by a base station known as an eNodeB or eNB (evolved NodeB) . More recently, LTE is evolving further towards the so-called 5G or NR (New Radio) systems where one or more cells are supported by a base station known as a gNB.

Support for multicast and broadcast services is added to NR. There are two delivery methods for the transmission of multicast and broadcast service (MBS) packet flows over radio. One method is a point-to-multipoint (PTM) delivery method in which a RAN node delivers a single copy of MBS data packets over radio to a set of UEs. The other method is a point-to-point (PTP) delivery method in which a RAN node delivers separate copies of MBS data packet over radio to individual UE.

RAN2 is working on two MBS delivery modes: Delivery mode 1 (DM1) and DM2. DM1 is used for multicast session delivery and is applicable to UEs in RRC connected state. The UE is provided with MBS configuration. DM1 can use both Point-to-Point and Point-to-Multipoint transmissions and can take advantage of UL UE feedback, e.g. 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, RRC idle and RRC inactive states.

RAN2 also defines two types of logical channels, i.e. an MBS Transport Channel (MTCH) and an MBS Control Channel (MCCH) , used at least for broadcast session delivery using DM2. The MBS Transport Channel also referred to as Multicast Transport Channel, and the MBS Control Channel also referred to as Multicast Control Channel. MTCH is a point-to-multipoint downlink channel for transmitting traffic data from the network to the UE. MCCH is a point-to-multipoint downlink channel used for transmitting MBS control information from the network to the UE, for one or several MTCHs.

A UE may be capable of receiving multicast/broadcast services in a mixed mode or a broadcast mode. Using mixed mode (i.e. DM1) , multicast and broadcast services may be delivered using either a MBS radio bearer (MRB) or a data radio bearer (DRB) for a UE in a radio resource control (RRC) connected state. Using broadcast mode (i.e. DM2) , multicast/broadcast services may be delivered using an MRB for a UE in an RRC connected state, an RRC idle state, or an RRC inactive state.

Technical Problem

MBS services can be received regardless of the radio resource control (RRC) states. However, upon the reception of DM1, the UE is required to stay in RRC connected state to handle MBS services/multicast session and is allowed to stay in RRC connected state when no data ongoing for the multicast session. Hence this first issue needs to be addressed. Furthermore, the UE can transit to RRC idle/inactive state. However, MBS service may require different values of data inactivity timer that is set per MAC entity. Once the data inactivity timer is set as a value, the value will be applied by the whole MAC entities. This second issue needs to be addressed.

Technical Solution

A first aspect of the present disclosure is to propose a method for processing multicast/broadcast service (MBS) executable in a user equipment includes: receiving multicast/broadcast service (MBS) data over MBS transport channel (MTCH) /MBS control channel (MCCH) that are configured by a multicast radio bearer (MRB) configuration from a base station; determining whether the user equipment (UE) is mandated to stay in RRC connected state when there is no data ongoing for multicast session; when the UE is mandated to stay in the RRC connected state, determining whether a data inactivity timer is applicable to MBS transport channel (MTCH) /MBS control channel (MCCH) ; when the data inactivity timer is applicable to the MTCH/MCCH, setting the data inactivity timer to a value indicative of an infinite duration; and when the data inactivity timer is not applicable to the MTCH/MCCH, disabling the data inactivity timer.

A second aspect of the disclosure provides a user equipment. The user equipment includes a memory storing instructions, and one or more processors operatively coupled to the memory. The processor executes the instructions to perform following operations comprising: receiving multicast/broadcast service (MBS) data over MBS transport channel (MTCH) /MBS control channel (MCCH) that are configured by a multicast radio bearer (MRB) configuration from a base station; determining whether the user equipment (UE) is mandated to stay in RRC connected state when there is no data ongoing for multicast session; when the UE is mandated to stay in the RRC connected state, determining whether a data inactivity timer is applicable to MBS transport channel (MTCH) /MBS control channel (MCCH) ; when the data inactivity timer is applicable to the MTCH/MCCH, setting the data inactivity timer to a value indicative of an infinite duration; and when the data inactivity timer is not applicable to the MTCH/MCCH, disabling the data inactivity timer.

A third aspect of the disclosure provides a method for processing multicast/broadcast service (MBS) executable in a base station. The method includes: transmitting, to a user equipment (UE) , multicast/broadcast service (MBS) data over MBS transport channel (MTCH) /MBS control channel (MCCH) that are configured by a multicast radio bearer (MRB) configuration; and transmitting a configuration to the UE so that the UE perform steps comprising: determining whether the user equipment (UE) is mandated to stay in RRC connected state when there is no data ongoing for multicast session; when the UE is mandated to stay in the RRC connected state, determining whether a data inactivity timer is applicable to MBS transport channel (MTCH) /MBS control channel (MCCH) ; when the data inactivity timer is applicable to the MTCH/MCCH, setting the data inactivity timer to a value indicative of an infinite duration; and when the data inactivity timer is not applicable to the MTCH/MCCH, disabling the data inactivity timer.

A fourth aspect of the disclosure provides a base station. The base station includes: a memory storing instructions and a transceiver transmitting, to a user equipment (UE) , multicast/broadcast service (MBS) data over MBS transport channel (MTCH) /MBS control channel (MCCH) that are configured by a multicast radio bearer (MRB) configuration, and transmitting a configuration to the UE so that the UE perform operations comprising: determining whether the user equipment (UE) is mandated to stay in RRC connected state when there is no data ongoing for multicast session; when the UE is mandated to stay in the RRC connected state, determining whether a data inactivity timer is applicable to MBS transport channel (MTCH) /MBS control channel (MCCH) ; when the data inactivity timer is applicable to the MTCH/MCCH, setting the data inactivity timer to a value indicative of an infinite duration; and when the data inactivity timer is not applicable to the MTCH/MCCH, disabling the data inactivity timer.

The disclosed method may be implemented in a chip. The chip may include a processor, configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute the disclosed method.

The disclosed method may be programmed as computer executable instructions stored in non-transitory computer readable medium. The non-transitory computer readable medium, when loaded to a computer, directs a processor of the computer to execute the disclosed method.

The non-transitory computer readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory.

The disclosed method may be programmed as computer program product, that causes a computer to execute the disclosed method.

The disclosed method may be programmed as computer program, that causes a computer to execute the disclosed method.

Advantageous Effects

Embodiments of the disclosure are provided to a method for processing multicast/broadcast service (MBS) , a base station and a user equipment. Upon the reception of DM1, the UE is capable of staying in RRC connected state to handle MBS services/multicast session and is allowed to stay in RRC connected state when no data ongoing for the multicast session by setting the data inactivity timer a value indicative of an infinite duration or disabling the data inactivity timer. By staying in RRC connected state when there is no data ongoing for multicast session, the UE can conserve resources (such as memory resources, processing resources, or battery power, among other examples) and use the maintained MRB to receive multicast session, which reduces latency and conserves signaling overhead associated with establishing the MRB. Furthermore, for the scenario that UE can transit to idle/inactive mode when no data ongoing, the present disclosure proposes that a value of the data inactivity timer for the DRB is replaced with a value of the data inactivity timer for the MRB, or a bigger value of the data inactivity timers for DRB and MRB is selected as the value of the inactivity timers of the DRB and the MRB. Accordingly, the DRB and the MRB for transmitting and receiving MBS data can be maintained for a longer time period even if no data ongoing.

Description of Drawings

In order to more clearly illustrate the embodiments of the present disclosure or related art, the following figures will be described in the embodiments are briefly introduced. It is obvious that the drawings are merely some embodiments of the present disclosure, a person having ordinary skill in this field can obtain other figures according to these figures without paying the premise.

Fig. 1 illustrates a schematic diagram showing a telecommunication system according to an embodiment of the present disclosure.

Fig. 2 illustrates a Downlink Layer 2 Architecture for Multicast Session.

Fig. 3 illustrates a Downlink Layer 2 Architecture for Broadcast Session.

Fig. 4 shows a flowchart of a method of MBS according to an embodiment of the present disclosure.

Fig. 5 depicts a method of handling MBS according to another embodiment of the present disclosure.

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

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the disclosure are described in detail with the technical matters, structural features, achieved objects, and effects with reference to the accompanying drawings as follows. Specifically, the terminologies in the embodiments of the present disclosure are merely for describing the purpose of the certain embodiment, but not to limit the disclosure.

With reference to Fig. 1, a telecommunication system including a UE 10, a base station 200, and a network entity device 30. Connections between devices and device components are shown as lines and arrows in the figures. The telecommunication system is operated in a wireless network which may be a Long Term Evolution (LTE) network or some other wireless network, such as a 5G or NR network. The UE 10 may include a processor 11, a memory 12, and a transceiver 13. The first 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 of the

processors

11, 201, and 301 may be configured to implement proposed functions, procedures and/or methods described in the description. Layers of radio interface protocol may be implemented in the

processors

11, 201 and 301. Each of the

memory

12, 202, and 302 operatively stores a variety of program and information to operate a connected processor. Each of the

transceiver

13, 203, and 303 is operatively coupled with a connected processor, transmits and/or receives radio signals or wireline signals. The base station 200 hosts the functions, such as inter-cell radio resource management (MME) , radio bearer (RB) control, connection mobility control, radio admission control, measurement configuration/provision, dynamic resource allocation (scheduler) . The base station 200 may be referred to as another terminology, such as evolved NodeB (eNB) , a gNB, an access point (AP) , or one of other types of radio nodes. In 3GPP, the term “cell” can refer to a coverage area of a BS or a BS subsystem serving this coverage area.

Each of the

processor

11, 201, and 301 may include an application-specific integrated circuits (ASICs) , other chipsets, logic circuits and/or data processing devices. Each of the

memory

12, 202, and 302 may include a read-only memory (ROM) , a random access memory (RAM) , a flash memory, a memory card, a storage medium and/or other storage devices. Each of the

transceiver

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 can be implemented with modules, procedures, functions, entities and so on, that perform the functions described herein. The modules can be stored in a memory and executed by the processors. The memory can be implemented within a processor or external to the processor, in which those can be communicatively coupled to the processor via various means are known in the art.

The network entity device 300 may be a node in a CN. CN may include LTE CN or 5G core (5GC) which includes user plane function (UPF) , session management function (SMF) , mobility management function (AMF) , unified data management (UDM) , policy control function (PCF) , control plane (CP) /user plane (UP) separation (CUPS) , authentication server (AUSF) , network slice selection function (NSSF) , and the network exposure function (NEF) .

UE 10 may transition among an RRC connected state, an RRC idle state, and an RRC inactive state. In the RRC inactive state, the UE maintains the RRC connection while reducing signaling and power consumption. In the RRC inactive state, the UE 10 may transition to the RRC connected state via RRC connection resumption (also referred to as RRC resume) , or may transition to the RRC idle state via RRC connection release or due to a connection failure. In the RRC connected state and the RRC inactive state, the UE is registered with and connected to the core network. In the RRC idle state, the UE is de-registered from the core network.

When the base station 200 detects the UE 10 which does not have any traffic to send and receive during a defined period of time, usually referred to a data inactivity timer (and also referred to as dataInactivityTimer in the LTE and NR protocol specifications of 3GPP) 204 (10 seconds, 20 second and so on) which is defined in the base station 200 and also is configurable, then the base station 200 can initiate RRC procedures to transit the UE 10 from radio resource control (RRC) connected state to RRC inactive state or RRC idle state. If there is no activity from the UE 10 for a short time, the UE 10 can suspend its session by moving to RRC inactivity state and can resume its session moving to the RRC connected state. In RRC idle state, the UE 10 does not have any connectivity to the network entity device 300, and all context relating to the UE 10 is removed from the E-UTRAN. When the UE 10 is idled with 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. S1-MME control plane and S1-U user plane connections are also removed.

Please refer to Fig. 2 and Fig. 3. Fig. 2 illustrates a Downlink Layer 2 Architecture for Multicast Session. Fig. 3 illustrates a Downlink Layer 2 Architecture for Broadcast Session. Target applications for Multicast and Broadcast Service (MBS) include radio broadcasting, live streaming video services, file delivery and emergency alerts. The multicast and broadcast content is transmitted over a geographical area referred to as an MBS zone. The MBS zone is a collection of one or more base stations transmitting the same content. Each base station capable of MBS service may belong to one or more MBS zones. Each MBS zone is identified by a unique zone identifier. A base station 200 may provide multicast and broadcast services corresponding to different MBS zones. The MBS data bursts may be transmitted in the form of several sub-packets, and these sub-packets may be transmitted in different time intervals to allow the UE 10 to combine the sub-packets without transmission of acknowledgement. The UEs 10 (including UEs 10a and 10b) in an MBS zone are assigned a common multicast station identifier. The MBS PDUs are transmitted by all base stations in the same MBS zone. The MBS service may be delivered via a dedicated RF carrier or a mixed unicast, multicast, and broadcast RF carrier. The UE 10 can receive the MBS content within the MBS zone in connected state or idle state.

The base station 200 may transmit an MRB/DRB configuration for an MRB/DRB in a radio link control (RLC) acknowledged mode (AM) to the UE 10. The term MRB/DRB may be used herein to refer to the MRB, the DRB, or both. In RLC AM, reliable transmission of multicast/broadcast traffic may be supported using acknowledgment (ACK) or negative acknowledgement (NACK) feedback and retransmissions. The ACK or NACK (referred to as ACK/NACK) feedback may be transmitted by the UE 10 in an RLC status report. The base station 200 may transmit the MRB/DRB configuration in a configuration message, such as 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 transmission of multicast/broadcast control messages. The MRB configuration may indicate an MBS transport channel (MTCH) for transmission of multicast/broadcast data. The DRB configuration may indicate a dedicated transport channel (DTCH) for transmission of multicast/broadcast data or unicast data. The DRB configuration may indicate a dedicated control channel (DCCH) for transmission of multicast/broadcast control messages or unicast control messages. For example, the MRB/DRB configuration may indicate resources (such as time domain resources, frequency domain resources, or spatial domain resources) allocated to the MCCH and the MTCH. The MRB configuration may indicate a group radio network temporary identifier (G-RNTI) associated with the MRB. The G-RNTI may be used to transmit communications and to receive communications on the MRB. In some embodiments, different multicast/broadcast subscriptions may be associated with different G-RNTIs.

The MRB configuration may indicate a retransmission configuration for multicast/broadcast traffic transmitted via the MRB. For example, the MRB configuration may indicate whether retransmissions are unicast retransmissions (which may use a cell radio network temporary identifier (C-RNTI) in a similar manner as a G-RNTI) , multicast/broadcast retransmissions (which may use a G-RNTI, as described above) , or capable of being switched between unicast and multicast/broadcast. The retransmission configuration may indicate one or more resources to be used for retransmissions.

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

The UE 10 may transition from the RRC connected state to the RRC idle state or RRC inactive state after the MRB has been configured, such as by exiting the connected state and entering one of the idle state or the inactive state. For example, the UE 10 may transition from an RRC connected state to an RRC idle state via RRC connection release. Alternatively, the UE may transition from the RRC connected state to the RRC inactive state via RRC connection suspension. When the connection between the UE 10 and the base station 200 is established (such as 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 for the MRB. The term idle/inactive state may be used herein to refer to the RRC idle state, the RRC inactive state, or both. A UE MAC may be configured by a UE RRC with a data inactivity monitoring functionality, when the UE 10 in RRC Connected state. The UE RRC may control data inactivity operation by configuring the data inactivity timer 204. Data inactivity timer may be used to control data inactivity operation. When the data inactivity timer 204 is configured, the UE 10 may start or restart data inactivity timer 204, if the UE 10 receives the MAC service data unit (SDU) for DTCH logical channel, DCCH logical channel, or CCCH logical channel. Or, the UE 10 may start or restart data inactivity timer 204, if the UE 10 transmits the MAC SDU for DTCH logical channel, or DCCH logical channel. If the data inactivity timer 204 expires, the UE 10 may indicate the expiry of the data inactivity timer 204 to upper layers. Specifically, upon expiry of the data inactivity timer 204, the UE 10 may perform actions upon leaving RRC connected state, with release cause “RRC connection failure” , and the UE 10 may leave RRC connected state and enter RRC IDLE state.

Referring to Fig. 1 and Fig. 4 showing a method of handling MBS according to an embodiment of the present disclosure, the method includes Block 302-Block 328 as introduced below.

Block 302: Receive multicast/broadcast service (MBS) data over MBS transport channel (MTCH) /MBS control channel (MCCH) that are configured by an MBS radio bearer (MRB) configuration from a base station 200. In this disclosure, the MBS data focuses on multicast data which may be transmitted in the RRC connected state but not transmitted in RRC idle/inactive state.

Block 304: Determine whether the UE 10 is mandated to stay in RRC connected state when there is no data ongoing for multicast session.

Block 306: When the UE 10 is mandated to stay in the RRC connected state, determine whether a data inactivity timer 204 is applicable to MTCH/MCCH.

Block 308: When the data inactivity timer 204 is applicable to the MTCH/MCCH, set the data inactivity timer to a value indicative of an infinite duration.

Block 310: When the data inactivity timer 204 is not applicable to the MTCH/MCCH, determine whether the UE 10 receives data radio bearer (DRB) data before receiving the MBS data.

Block 312: When the UE 10 receives DRB data before receiving MBS data, determine whether the data inactivity timer 204 has been configured during a DRB configuration procedure.

Block 314: When the UE 10 does not receive DRB data before receiving the MBS data, disabling the data inactivity timer 204.

Block 316: Disable the data inactivity timer 204 during a DRB configuration procedure when the UE 10 needs to receive the DRB data.

Block 318: When the data inactivity timer 204 has not been configured during the DRB configuration procedure, disabling the data inactivity timer 204.

Block 320: When the data inactivity timer 204 has been configured during the DRB configuration procedure, stop the data inactivity timer 204 during the MRB configuration procedure.

Block 322: When the UE 10 is not mandated to stay in the RRC connected state, enable the data inactivity timer 204 applicable to the MTCH/MCCH.

Block 324: Determine whether values of the data inactivity timer 204 are shared by a data radio bearer (DRB) and an MBS radio bearer (MRB) .

Block 326: When values of the data inactivity timer are shared by the DRB and the MRB, replace a value of the data inactivity timer 204 for the DRB with a value of the data inactivity timer 204 for the MRB, or select a bigger value of the data inactivity timers 204 as the value of the inactivity timers 204 of the DRB and the MRB.

Block 328: When values of the data inactivity timer 204 are not shared by the DRB and the MRB, set the values of the data inactivity timers 204 of the DRB and the MRB as the same value or different values.

According to the present disclosure, the method provides mechanism of the following two scenarios. Block 304-Block 320 are operated for the scenario that UE needs to stay in connected mode when no data ongoing for multicast session, and Block 322-Block 328 are operated for the scenario that UE can transit to idle/inactive mode when no data ongoing.

When multicast/broadcast service (MBS) data over MBS transport channel (MTCH) /MBS control channel (MCCH) that are configured by the multicast radio bearer (MRB) configuration from the base station 200, the UE 10 determines whether the UE 10 is mandated to stay in RRC connected state when there is no data ongoing for multicast session. If the UE 10 is mandated to stay in the RRC connected state, the UE 10 determines whether a data inactivity timer 204 is applicable to MBS transport channel (MTCH) /MBS control channel (MCCH) . If the data inactivity timer 204 is applicable to the MTCH/MCCH, set the data inactivity timer 204 to a value indicative of an infinite duration. As shown in Table 1, the data inactivity timer 204 is preset as one of predefined values, such as s1, s2, ……, s180. Once the data inactivity timer 204 is set to a value indicative of an infinite duration, expiration of the data inactivity timer 204 will not occur. Accordingly, the UE 10 can maintain in the RRC connected state even if there is no data ongoing for multicast session.

TABLE 1

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

In block 314, when the UE 10 does not receive DRB data before receiving the MBS data, the data inactivity timer 204 is disabled during the MRB configuration procedure or in response to a disabling information included in the RRC signaling, Medium access control (MAC) control element (CE) , or downlink control information (DCI) sent from the base station 200. Disabling the data inactivity timer 204 can be realized by not configuring the data inactivity timer 204. Since the data inactivity timer 204 is not configured, the data inactivity timer 204 can not be triggered so that the UE 10 can maintain in the RRC connected state even if there is no data ongoing for multicast session.

In block 312, when the UE 10 receives DRB data before receiving MBS data, the UE 10 determines whether the data inactivity timer 204 has been configured during a DRB configuration procedure. When the data inactivity timer 204 has not been configured during the DRB configuration procedure, the data inactivity timer 204 is disabled during the MRB configuration procedure or in response to a disabling information included in the RRC signaling, the MAC CE, or the DCI sent from the base station 200. Disabling the data inactivity timer 204 can be realized by not configuring the data inactivity timer 204. Since the data inactivity timer 204 is not configured, the data inactivity timer 204 can not be triggered so that the UE 10 can maintain in the RRC connected state even if there is no data ongoing for multicast session.

In block 320, when the data inactivity timer 204 has been configured during the DRB configuration procedure, stop the data inactivity timer 204 during the MRB configuration procedure or in response to a disabling information included in the RRC signaling, the MAC CE, or the DCI sent from the base station 200. Since the data inactivity timer 204 is not configured to the MRB configuration procedure, the data inactivity timer 204 can not be triggered so that the UE 10 can maintain in the RRC connected state even if there is no data ongoing for multicast session.

Refer to Fig. 5 depicts a method of handling MBS according to another embodiment of the present disclosure. Furthermore, in block 330, even if the UE 10 is mandated to stay in the RRC connected state (block 304) , the UE 10 may enter RRC idle/inactive state in response to some predetermined conditions such as whether the power level of the UE 10 is lower than a threshold. According to one embodiment, when the power level of the UE 10 is lower than a threshold (e.g., 20%of a battery power) , the UE 10 is triggered to enter RRC idle/inactive state. The UE 10 may automatically transition from RRC connected state to the RRC idle/inactive state, and send to the base station 200 a message that the UE 10 has been entered to the RRC idle/inactive state. In another embodiment, when the power level of the UE 10 is lower than the threshold, the UE 10 transmits to the base station 200 a request of entering the RRC idle/inactive state. Then, the base station 200 delivers a command of entering the RRC idle/inactive state to the UE 10, so that the UE 10 transitions from RRC connected state to the RRC idle/inactive state in response to the command of entering the RRC idle/inactive state.

The present disclosure also proposes another solution for the scenario that UE can transit to idle/inactive mode when no data ongoing. In Block 322, when the UE 10 is not mandated to stay in the RRC connected state, the data inactivity timer 204 applicable to the MTCH/MCCH is enabled. Then, the UE 10 determines whether values of the data inactivity timer 204 are shared by a data radio bearer (DRB) and a multicast/broadcast radio bearer (MRB) .

When values of the data inactivity timer 204 are not shared by the DRB and the MRB, the values of the data inactivity timers 204 of the DRB and the MRB may be set as different values, for example, as shown below:

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 values of the data inactivity timer 204 are not shared by the DRB and the MRB, the values of the data inactivity timers 204 of the DRB and the MRB may be overlapped, or set as the same different values, for example, as shown below:

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

In block 328, when values of the data inactivity timer are shared by the DRB and the MRB, a value of the data inactivity timer 204 for the DRB is replaced with a value of the data inactivity timer 204 for the MRB. In this embodiment, the UE 10 may determine the value of the data inactivity timer 204 for the MRB as a higher priority, and thus replaces the value of the data inactivity timer 204 for the DRB with the value of the data inactivity timer 204 for the MRB. For example, if the value of the data inactivity timer 204 for the MRB is s150 (150 second) and the value of the data inactivity timer 204 for the DRB is s180 (180 second) , the UE 10 replaces the value of the data inactivity timer 204 for the DRB from “s180” to “s150. ”

In another embodiment, when values of the data inactivity timer are shared by the DRB and the MRB, a bigger value of the data inactivity timers 204 is selected as the value of the inactivity timers 204 of the DRB and the MRB. For example, if the value of the data inactivity timer 204 for the MRB is s150 (150 second) and the value of the data inactivity timer 204 for the DRB is s180 (180 second) , the UE 10 determines the value (s180) of the data inactivity timer 204 for the DRB is bigger than the value (s150) of the data inactivity timer 204 for the MRB. Therefore, the UE 10 replaces the value of the data inactivity timer 204 for the MRB from “s150” to “s180. ”

For the scenario that UE can transit to idle/inactive mode when no data ongoing, the present disclosure proposes that a value of the data inactivity timer for the DRB is replaced with a value of the data inactivity timer for the MRB, or a bigger value of the data inactivity timers for DRB and MRB is selected as the value of the inactivity timers of the DRB and the MRB. Accordingly, the DRB and the MRB for transmitting and receiving MBS data can be maintained for a longer time period even if no data ongoing.

Fig. 6 is a block diagram of an example system 700 for wireless communication according to an embodiment of the present disclosure. Embodiments described herein may be implemented into the system using any suitably configured hardware and/or software. Fig. 6 illustrates the system 700 including a radio frequency (RF) circuitry 710, a baseband circuitry 720, a processing unit 730, a memory/storage 740, a display 750, a camera 760, a sensor 770, and an input/output (I/O) interface 780, coupled with each other as illustrated.

The processing unit 730 may include a circuitry, such as, but not limited to, one or more single-core or multi-core processors. The processors may include any combinations of general-purpose processors and dedicated processors, such as graphics processors and application processors. The processors may be coupled with the memory/storage and configured to execute instructions stored in the memory/storage to enable various applications and/or operating systems running on the system. The RF circuitry 710, baseband circuitry 720, processing unit 730, memory/storage 740, display 750, camera 760, sensor 770, and I/O interface 780 are well-known elements in the system 700 such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, an ultrabook, a smartphone, etc. In addition, the instructions as a software product can be stored in a readable storage medium in a computer. The software product in the computer is stored in a storage medium, including a plurality of commands for a computational device (such as a personal computer, a server, or a network device) to run all or some of the steps disclosed by the embodiments of the present disclosure. The storage medium includes a USB disk, a mobile hard disk, a read-only memory (ROM) , a random access memory (RAM) , a floppy disk, or other kinds of media capable of storing program codes.

The embodiment of the present disclosure is a combination of techniques/processes that can be adopted in 3GPP specification to create an end product. Embodiments of the disclosure are provided to a method for processing multicast/broadcast service (MBS) , a base station and a user equipment. Upon the reception of DM1, the UE is capable of staying in RRC connected state to handle MBS services/multicast session and is allowed to stay in RRC connected state when no data ongoing for the multicast session by setting the data inactivity timer a value indicative of an infinite duration or disabling the data inactivity timer. By staying in RRC connected state when there is no data ongoing for multicast session, the UE can conserve resources (such as memory resources, processing resources, or battery power, among other examples) and use the maintained MRB to receive multicast session, which reduces latency and conserves signaling overhead associated with establishing the MRB. Furthermore, for the scenario that UE can transit to idle/inactive mode when no data ongoing, the present disclosure proposes that a value of the data inactivity timer for the DRB is replaced with a value of the data inactivity timer for the MRB, or a bigger value of the data inactivity timers for DRB and MRB is selected as the value of the inactivity timers of the DRB and the MRB. Accordingly, the DRB and the MRB for transmitting and receiving MBS data can be maintained for a longer time period even if no data ongoing.

While the present disclosure has been described in connection with what is considered the most practical and preferred embodiments, it is understood that the present disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.

Claims

A method for processing multicast/broadcast service (MBS) executable in a user equipment, comprising:

receiving multicast/broadcast service (MBS) data over MBS transport channel (MTCH) /MBS control channel (MCCH) that are configured by a multicast radio bearer (MRB) configuration from a base station;

determining whether the user equipment (UE) is mandated to stay in RRC connected state when there is no data ongoing for multicast session;

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

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

when the data inactivity timer is not applicable to the MTCH/MCCH, disabling the data inactivity timer.
The method of claim 1, further comprising:

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.
The method of claim 2, further comprising:

when the UE receives DRB data before receiving MBS data, determining whether the data inactivity timer has been configured during a DRB configuration procedure;

when the data inactivity timer has been configured during the DRB configuration procedure, stopping the data inactivity timer; and

when the data inactivity timer has not been configured during the DRB configuration procedure, disabling the data inactivity timer.
The method of claim 3, wherein the stopping the data inactivity timer comprises:

stopping the data inactivity timer during the MRB configuration procedure, or in response to a stop information included in RRC signaling, Medium access control (MAC) control element (CE) , or downlink control information (DCI) ; and

the disabling the data inactivity timer comprises:

disabling the data inactivity timer during the MRB configuration procedure, or in response to a disabling information included in the RRC signaling, the MAC CE, or the DCI.
The method of claim 2, further comprising:

when the UE does not receive DRB data before receiving the MBS data, disabling the data inactivity timer.
The method of claim 5, wherein the disabling the data inactivity timer comprises:

disabling the data inactivity timer during the MRB configuration procedure, or in response to a disabling information included in the RRC signaling, the MAC CE, or the DCI.
The method of claim 5, further comprising:

disabling the data inactivity timer during a DRB configuration procedure or in response to a disabling information included in the RRC signaling, the MAC CE, or the DCI, when the UE receives the DRB data before receiving the MBS data.
The method of claim 1, wherein after the UE is mandated to stay in the RRC connected state, the method further comprises:

in response to a condition, triggering the UE to enter RRC idle/inactive state.
The method of claim 8, wherein after the triggering the UE to enter RRC idle/inactive state, the method further comprises:

transmitting to the base station a message that the UE has been entered to the RRC idle/inactive state.
The method of claim 8, wherein the triggering the UE to enter the RRC idle/inactive state comprises:

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

entering the RRC idle/inactive state in response to a command of entering the RRC idle/inactive state sent from the base station.
The method of claim 8, wherein the condition comprises determining whether a power level of the UE is lower than a threshold.
The method of claim 1, further comprising:

when the UE is not mandated to stay in the RRC connected state, enabling the data inactivity timer applicable to the MTCH/MCCH.
The method of claim 11, further comprising:

determining whether values of the data inactivity timer are shared by a data radio bearer (DRB) and an MBS radio bearer (MRB) .
The method of claim 13, further comprising:

when values of the data inactivity timer are shared by the DRB and the MRB, replacing a value of the data inactivity timer for the DRB with a value of the data inactivity timer for the MRB.
The method of claim 13, further comprising:

when values of the data inactivity timers are shared by the DRB and the MRB, selecting a bigger value of the data inactivity timers as the value of the inactivity timers of the DRB and the MRB.
The method of claim 13, further comprising:

when values of the data inactivity timer are not shared by the DRB and the MRB, setting the values of the data inactivity timers of the DRB and the MRB as the same value or different values.
A user equipment, comprising:

a memory, storing instructions; and

one or more processors operatively coupled to the memory, wherein the processor executes the instructions to perform following operations comprising:

receiving multicast/broadcast service (MBS) data over MBS transport channel (MTCH) /MBS control channel (MCCH) that are configured by a multicast radio bearer (MRB) configuration from a base station;

determining whether the user equipment (UE) is mandated to stay in RRC connected state when there is no data ongoing for multicast session;

when the UE is mandated to stay in the RRC connected state, determining whether a data inactivity timer is applicable to MBS transport channel (MTCH) /MBS control channel (MCCH) ;

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

when the data inactivity timer is not applicable to the MTCH/MCCH, disabling the data inactivity timer.
The user equipment of claim 17, further comprising:

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.
The user equipment of claim 18, further comprising:

when the UE receives DRB data before receiving MBS data, determining whether the data inactivity timer has been configured during a DRB configuration procedure;

when the data inactivity timer has been configured during the DRB configuration procedure, stopping the data inactivity timer; and

when the data inactivity timer has not been configured during the DRB configuration procedure, disabling the data inactivity timer.
The user equipment of claim 19, wherein the stopping the data inactivity timer comprises:

stopping the data inactivity timer during the MRB configuration procedure, or in response to a stop information included in RRC signaling, Medium access control (MAC) control element (CE) , or downlink control information (DCI) ; and

the disabling the data inactivity timer comprises:

disabling the data inactivity timer during the MRB configuration procedure, or in response to a disabling information included in the RRC signaling, the MAC CE, or the DCI.
The user equipment of claim 18, further comprising:

when the UE does not receive DRB data before receiving the MBS data, disabling the data inactivity timer.
The user equipment of claim 21, wherein the disabling the data inactivity timer comprises:

disabling the data inactivity timer during the MRB configuration procedure, or in response to a disabling information included in the RRC signaling, the MAC CE, or the DCI.
The user equipment of claim 21, further comprising:

disabling the data inactivity timer during a DRB configuration procedure or in response to a disabling information included in the RRC signaling, the MAC CE, or the DCI, when the UE receives the DRB data before receiving the MBS data.
The user equipment of claim 17, wherein after the UE is mandated to stay in the RRC connected state, the method further comprises:

in response to a condition, triggering the UE to enter RRC idle/inactive state.
The user equipment of claim 23, wherein after the triggering the UE to enter RRC idle/inactive state, the method further comprises:

transmitting to the base station a message that the UE has been entered to the RRC idle/inactive state.
The user equipment of claim 23, wherein the triggering the UE to enter the RRC idle/inactive state comprises:

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

entering the RRC idle/inactive state in response to a command of entering the RRC idle/inactive state sent from the base station.
The user equipment of claim 23, wherein the condition comprises determining whether a power level of the UE is lower than a threshold.
The user equipment of claim 17, further comprising:

when the UE is not mandated to stay in the RRC connected state, enabling the data inactivity timer applicable to the MTCH/MCCH.
The user equipment of claim 27, further comprising:

determining whether values of the data inactivity timer are shared by a data radio bearer (DRB) and an MBS radio bearer (MRB) .
The user equipment of claim 28, further comprising:

when values of the data inactivity timer are shared by the DRB and the MRB, replacing a value of the data inactivity timer for the DRB with a value of the data inactivity timer for the MRB.
The user equipment of claim 28, further comprising:

when values of the data inactivity timers are shared by the DRB and the MRB, selecting a bigger value of the data inactivity timers as the value of the inactivity timers of the DRB and the MRB.
The user equipment of claim 28, further comprising:

when values of the data inactivity timer are not shared by the DRB and the MRB, setting the values of the data inactivity timers of the DRB and the MRB as the same value or different values.
A method for processing multicast/broadcast service (MBS) executable in a base station, comprising:

transmitting, to a user equipment (UE) , multicast/broadcast service (MBS) data over MBS transport channel (MTCH) /MBS control channel (MCCH) that are configured by a multicast radio bearer (MRB) configuration;

transmitting a configuration to the UE so that the UE perform steps comprising:

determining whether the UE is mandated to stay in RRC connected state when there is no data ongoing for multicast session;

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

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

when the data inactivity timer is not applicable to the MTCH/MCCH, disabling the data inactivity timer.
The method of claim 32, further comprising:

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.
The method of claim 33, further comprising:

when the UE receives DRB data before receiving MBS data, determining whether the data inactivity timer has been configured during a DRB configuration procedure;

when the data inactivity timer has been configured during the DRB configuration procedure, stopping the data inactivity timer; and

when the data inactivity timer has not been configured during the DRB configuration procedure, disabling the data inactivity timer.
The method of claim 34, further comprising:

transmitting to the UE the MRB configuration procedure or a stop/disabling information included in RRC signaling, Medium access control (MAC) control element (CE) , or downlink control information (DCI) ;

wherein the stopping the data inactivity timer comprises:

stopping the data inactivity timer during the MRB configuration procedure, or in response to the stop information; and

the disabling the data inactivity timer comprises:

disabling the data inactivity timer during the MRB configuration procedure, or in response to the disabling information.
The method of claim 33, further comprising:

when the UE does not receive DRB data before receiving the MBS data, disabling the data inactivity timer.
The method of claim 36, further comprising:

transmitting to the UE the MRB configuration procedure or a disabling information included in RRC signaling, Medium access control (MAC) control element (CE) , or downlink control information (DCI) ;

wherein the disabling the data inactivity timer comprises:

disabling the data inactivity timer during the MRB configuration procedure, or in response to the disabling information.
The method of claim 36, further comprising:

transmitting to the UE a DRB configuration procedure or a disabling information included in RRC signaling, Medium access control (MAC) control element (CE) , or downlink control information (DCI) ;

wherein the disabling the data inactivity timer comprises:

disabling the data inactivity timer during the DRB configuration procedure, or in response to the disabling information.
The method of claim 32, wherein after the UE is mandated to stay in the RRC connected state, the method further comprises:

when a power level of the UE is lower than a threshold, receiving, from the UE, a message that the UE has been entered to the RRC idle/inactive state.
The method of claim 32, further comprising:

when a power level of the UE is lower than a threshold, receiving, from the UE, a request of entering the RRC idle/inactive state; and

transmitting a command of entering the RRC idle/inactive state to the UE.
The method of claim 32, further comprising:

when the UE is not mandated to stay in the RRC connected state, enabling the data inactivity timer applicable to the MTCH/MCCH.
The method of claim 41, further comprising:

determining whether values of the data inactivity timer are shared by a data radio bearer (DRB) and an MBS radio bearer (MRB) .
The method of claim 42, further comprising:

when values of the data inactivity timer are shared by the DRB and the MRB, replacing a value of the data inactivity timer for the DRB with a value of the data inactivity timer for the MRB.
The method of claim 43, further comprising:

when values of the data inactivity timers are shared by the DRB and the MRB, selecting a bigger value of the data inactivity timers as the value of the inactivity timers of the DRB and the MRB.
The method of claim 44, further comprising:

when values of the data inactivity timer are not shared by the DRB and the MRB, setting the values of the data inactivity timers of the DRB and the MRB as the same value or different values.
A base station, comprising:

a memory, storing instructions;

one or more processors operatively coupled to the memory, wherein the processor executes the instructions to perform the method of any one of claims 32-45.
A chip, comprising:

a processor, configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute the method of any one of claims 1-16.
A computer readable storage medium, in which a computer program is stored, wherein the computer program causes a computer to execute the method of any one of claims 1-16.
A computer program product, comprising a computer program, wherein the computer program causes a computer to execute the method of any one of claims 1-16.