WO2022236592A1

WO2022236592A1 - Method, device and computer readable medium for communication

Info

Publication number: WO2022236592A1
Application number: PCT/CN2021/092813
Authority: WO
Inventors: Zhe Chen; Gang Wang
Original assignee: Nec Corporation
Priority date: 2021-05-10
Filing date: 2021-05-10
Publication date: 2022-11-17

Abstract

Embodiments of the present disclosure relate to methods, devices and computer readable media for communication. According to embodiments of the present disclosure, a terminal device receives, from a network device a system information block for a multimedia broadcast multicast service (MBMS) control channel (MCCH) configuration. The system information block indicates an identity of a MCCH which is selected from a pluralities identities. The terminal device transmits a request for establishing a multicast radio bearer (MRB) associated with the MCCH to the network device. In this way, the terminal device can differentiate multiple MCCH.

Description

METHOD, DEVICE AND COMPUTER READABLE MEDIUM FOR COMMUNICATION

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to the field of telecommunication, and in particular, to methods, devices and computer storage media for communication.

BACKGROUND

With development of communication technologies, several solutions have been proposed to provide efficient and reliable solutions for communication. For example, Multicast and Broadcast Service (MBS) has been proposed to make it possible for efficient use of radio and network resources while transmitting audio and video content to a large group of end users. The term “MBS” used herein refers to a point-to-multipoint communication scheme where data packets are transmitted simultaneously from a single source to multiple destinations. MBS is a point-to-multipoint communication scheme where data packets are transmitted simultaneously from a single source to multiple destinations. The term broadcast refers to the ability to deliver content to all users. Multicast, on the other hand, refers to distribution of content among a specific group of users that are subscribed to those services.

SUMMARY

In general, embodiments of the present disclosure provide methods, devices and computer storage media for MBS multi radio bearer configuration.

In a first aspect, there is provided a method of communication. The method comprises: receiving, at a terminal device and from a network device, a system information block for a multimedia broadcast multicast service (MBMS) control channel (MCCH) configuration, the system information block indicating an identity of a MCCH; and transmitting, to the network device, a request for establishing a multicast radio bearer (MRB) associated with the MCCH.

In a second aspect, there is provided a method of communication. The method comprises: transmitting, at a network device and to a terminal device, a system information block for a multimedia broadcast multicast service (MBMS) control channel (MCCH) configuration, the system information block indicating an identity of a MCCH; and receiving, from the terminal device, a request for establishing a multicast radio bearer (MRB) associated with the MCCH.

In a third aspect, there is provided a method of communication. The method comprises: receiving, at a first network device and from a terminal device, a radio resource control (RRC) reestablishment request; transmitting, at the first network device and to a second network device, a request for retrieving a user equipment (UE) context; receiving, from the second network device, a UE context response indicating a configuration of a multicast radio bearer (MRB) which is configured at the terminal device; and transmitting, to the terminal device, a RRC reconfiguration for a data radio bearer (DRB) configuration, the DRB reconfiguration associated with an identity of the MRB.

In a fourth aspect, there is provided a terminal device. The terminal device comprises a circuitry configured to perform: receiving, from a network device, a system information block for a multimedia broadcast multicast service (MBMS) control channel (MCCH) configuration, the system information block indicating an identity of a MCCH; and transmitting, to the network device, a request for establishing a multicast radio bearer (MRB) associated with the MCCH.

In a fifth aspect, there is provided a network device. The network device comprises a circuitry configured to perform: transmitting, to a terminal device, a system information block for a multimedia broadcast multicast service (MBMS) control channel (MCCH) configuration, the system information block indicating an identity of a MCCH; and receiving, from the terminal device, a request for establishing a multicast radio bearer (MRB) associated with the MCCH.

In a sixth aspect, there is provided a network device. The network device comprises a circuitry configured to perform: receiving, at a first network device and from a terminal device, a radio resource control (RRC) reestablishment request; transmitting, at the first network device and to a second network device, a request for retrieving a user equipment (UE) context; receiving, from the second network device, a UE context response indicating a configuration of a multicast radio bearer (MRB) which is configured at the terminal device; and transmitting, to the terminal device, a RRC reconfiguration for a data radio bearer (DRB) configuration, the DRB reconfiguration associated with an identity of the MRB.

In a seventh aspect, there is provided a computer readable medium having instructions stored thereon. The instructions, when executed on at least one processor, cause the at least one processor to perform the method according to the first, second or third aspect of the present disclosure.

Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become more apparent, wherein:

Fig. 1 is a schematic diagram of a communication environment in which embodiments of the present disclosure can be implemented;

Fig. 2 illustrates a flow chart of an example method of communication implemented at a source network device in accordance with some embodiments of the present disclosure;

Fig. 3 illustrates a schematic diagram of an architecture of a multicast session in accordance with some embodiments of the present disclosure;

Fig. 4 illustrates a flow chart of an example method of communication implemented at a terminal device in accordance with some embodiments of the present disclosure;

Fig. 5 illustrates a flow chart of an example method of communication implemented at a network device in accordance with some embodiments of the present disclosure;

Fig. 6 illustrates a flow chart of an example method of communication implemented at a network device in accordance with some embodiments of the present disclosure; and

Fig. 7 is a simplified block diagram of a device that is suitable for implementing embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitations as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

As used herein, the term “terminal device” refers to any device having wireless or wired communication capabilities. Examples of the terminal device include, but not limited to, user equipment (UE) , personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs) , portable computers, tablets, wearable devices, internet of things (IoT) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, device on vehicle for V2X communication where X means pedestrian, vehicle, or infrastructure/network, or image capture devices such as digital cameras, gaming devices, music storage and playback appliances, or Internet appliances enabling wireless or wired Internet access and browsing and the like. The term “terminal device” can be used interchangeably with a UE, a mobile station, a subscriber station, a mobile terminal, a user terminal or a wireless device. In addition, the term “network device” refers to a device which is capable of providing or hosting a cell or coverage where terminal devices can communicate. Examples of a network device include, but not limited to, a Node B (NodeB or NB) , an Evolved NodeB (eNodeB or eNB) , a next generation NodeB (gNB) , a Transmission Reception Point (TRP) , a Remote Radio Unit (RRU) , a radio head (RH) , a remote radio head (RRH) , a low power node such as a femto node, a pico node, and the like.

In one embodiment, the terminal device may be connected with a first network device and a second network device. One of the first network device and the second network device may be a master node and the other one may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs) . In one embodiment, the first network device may be a first RAT device and the second network device may be a second RAT device. In one embodiment, the first RAT device is eNB and the second RAT device is gNB. Information related with different RATs may be transmitted to the terminal device from at least one of the first network device and the second network device. In one embodiment, first information may be transmitted to the terminal device from the first network device and second information may be transmitted to the terminal device from the second network device directly or via the first network device. In one embodiment, information related with configuration for the terminal device configured by the second network device may be transmitted from the second network device via the first network device. Information related with reconfiguration for the terminal device configured by the second network device may be transmitted to the terminal device from the second network device directly or via the first network device.

As used herein, the singular forms ‘a’ , ‘an’ and ‘the’ are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term ‘includes’ and its variants are to be read as open terms that mean ‘includes, but is not limited to. ’ The term ‘based on’ is to be read as ‘at least in part based on. ’ The term ‘one embodiment’ and ‘an embodiment’ are to be read as ‘at least one embodiment. ’ The term ‘another embodiment’ is to be read as ‘at least one other embodiment. ’ The terms ‘first, ’ ‘second, ’ and the like may refer to different or same objects. Other definitions, explicit and implicit, may be included below.

In some examples, values, procedures, or apparatus are referred to as ‘best, ’ ‘lowest, ’ ‘highest, ’ ‘minimum, ’ ‘maximum, ’ or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections.

The term “circuitry” used herein may refer to hardware circuits and/or combinations of hardware circuits and software. For example, the circuitry may be a combination of analog and/or digital hardware circuits with software/firmware. As a further example, the circuitry may be any portions of hardware processors with software including digital signal processor (s) , software, and memory (ies) that work together to cause an apparatus, such as a terminal device or a network device, to perform various functions. In a still further example, the circuitry may be hardware circuits and or processors, such as a microprocessor or a portion of a microprocessor, that requires software/firmware for operation, but the software may not be present when it is not needed for operation. As used herein, the term circuitry also covers an implementation of merely a hardware circuit or processor (s) or a portion of a hardware circuit or processor (s) and its (or their) accompanying software and/or firmware.

As mentioned above, the MBS has been proposed. The UE should register the MBS service. The term “MBS radio bearer (MRB) ” used herein can be defined as for transporting multicast and broadcast traffic in a point to point (PTP) or point to multipoint (PTM) mode. Multiple multimedia broadcast multicast service (MBMS) control channel (MCCH) may be supported. Multiple-MCCH case may also be discussed considering that 5G network is demanded to supply more diverse service types with different latency requirements. Since a MRB can include PTM or PTP mode, a radio resource control (RRC) re-establishment procedure may cause an issue of MRB to data radio bearer (DRB) convert.

In a long term evolution (LTE) system, the UE applies the single cell multicast radio bearer (SC-MRB) establishment procedure to start receiving a session of a MBMS service it has an interest in. The procedure may be initiated based on at least one of: a start of the MBMS session, entering a cell providing via SC-MRB a MBMS service in which the UE has interest, becoming interested in the MBMS service, removal of UE capability limitations inhibiting reception of the concerned service. In this case, the SC-MRB is fully established by UE internal behaviour and no network configuration involves.

In a new radio (NR) system, after the bearer is established by the UE, the UE should inform the network about the bearer, in order to guarantee quality of service of the bearer. Further, in NR, multiple MCCH is supported but the UE cannot differentiate the multiple MCCH.

In order to solve at least part of above problems, solutions on MBMS MRB MCCH are needed. According to embodiments of the present disclosure, a terminal device receives, from a network device a system information block for a multimedia broadcast multicast service (MBMS) control channel (MCCH) configuration. The system information block indicates an identity of a MCCH which is selected from a pluralities identities. The terminal device transmits a request for establishing a multicast radio bearer (MRB) associated with the MCCH to the network device. In this way, the terminal device can differentiate multiple MCCH.

Fig. 1 illustrates a schematic diagram of a communication system in which embodiments of the present disclosure can be implemented. The communication system 100, which is a part of a communication network, comprises a terminal device 110-1, a terminal device 110-2, ..., a terminal device 110-N, which can be collectively referred to as “terminal device (s) 110. ” The number N can be any suitable integer number.

The communication system 100 further comprises a network device 120-1, a network device 120-2, ..., a network device 120-M, which can be collectively referred to as “network device (s) 120. ” The number M can be any suitable integer number. In the communication system 100, the network devices 120 and the terminal devices 110 can communicate data and control information to each other. The numbers of devices shown in Fig. 1 are given for the purpose of illustration without suggesting any limitations.

Communications in the communication system 100 may be implemented according to any proper communication protocol (s) , comprising, but not limited to, cellular communication protocols of the first generation (1G) , the second generation (2G) , the third generation (3G) , the fourth generation (4G) and the fifth generation (5G) and on the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and/or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Divided Multiple Address (CDMA) , Frequency Divided Multiple Address (FDMA) , Time Divided Multiple Address (TDMA) , Frequency Divided Duplexer (FDD) , Time Divided Duplexer (TDD) , Multiple-Input Multiple-Output (MIMO) , Orthogonal Frequency Divided Multiple Access (OFDMA) and/or any other technologies currently known or to be developed in the future.

Embodiments of the present disclosure can be applied to any suitable scenarios. For example, embodiments of the present disclosure can be implemented at reduced capability NR devices. Alternatively, embodiments of the present disclosure can be implemented in one of the followings: NR multiple-input and multiple-output (MIMO) , NR sidelink enhancements, NR systems with frequency above 52.6GHz, an extending NR operation up to 71GHz, narrow band-Internet of Thing (NB-IOT) /enhanced Machine Type Communication (eMTC) over non-terrestrial networks (NTN) , NTN, UE power saving enhancements, NR coverage enhancement, NB-IoT and LTE-MTC, Integrated Access and Backhaul (IAB) , NR Multicast and Broadcast Services, or enhancements on Multi-Radio Dual-Connectivity.

Fig. 2 shows a signaling chart illustrating process 200 among devices according to some example embodiments of the present disclosure. Only for the purpose of discussion, the process 200 will be described with reference to Fig. 1. The process 200 may involve the terminal device 110-1, the network device 120-1 and the network device 120-2 in Fig. 1. It should be noted that the process 200 is only an example not limitation.

The network device 120-1 transmits 2005 a system information block to the terminal device 110-1. The system information block indicates an identity of a MCCH. For example, if a plurality of MCCHs are configured, there can be the plurality of identities for the plurality of MCCHs. The system information block can comprise a list of MCCH configurations. Each of the MCCH configuration may comprises one MCCH identity.. In this way, the terminal device 110-1 can differentiate multiple MCCH. In some embodiments, the system information block can comprise a quality of service (QoS) flow identity mapped for the MCCH. The system information block can also comprise a MBS service type. For example, the MBS service type comprises at least one of: MBS service information, MBS session information or a temporary mobile group identity. The terminal device 110-1 can determine a target MCCH configuration from the list of MCCH configurations based on the MBS service type. Alternatively or in addition, the system information block can comprise a multicast broadcast service (MBS) configuration. Table 1 below shows an example of the system information block. It should be noted that Table 1 is only an example not limitation.

Table 1

In some embodiments, the MBS configuration can indicate a MBS area list where the MCCH configuration is available. Table 2 below shows an example of the MBS configuration. It should be noted that Table 2 is only an example not limitation.

Table 2

Alternatively or in addition, the network device 120-1 can transmit 2008 a multicast traffic channel (MTCH) configuration to the terminal device 110-1. For example, the MTCH configuration can comprise the identity of the MCCH. Alternatively or in addition, the MTCH configuration can comprise a QoS flow identity to indicate the QoS flow being served. Table 3 below shows an example of the MTCH configuration. It should be noted that Table 3 is only an example not limitation.

Table 3

The network device 120-1 can transmit 2010 downlink control information (DCI) to the terminal device 110-1. In some embodiments, the downlink control information can comprise one or more identities of MCCHs which are to be updated. Alternatively or in addition, the downlink control information can indicate one or more multimedia broadcast single frequency network (MBSFN) areas to be updated. In LTE MBMS, the network device 120-1 can send DCI format 1C to update the MCCH. In DCI 1C, information for MCCH change notification can be used to update the MCCH. For example, the information for MCCH change notification can be 8 bits bitmap, which is to indicate which MBSFN area is updated. In some embodiments, a MCCH list can be included in the DCI in order to allow the network device 120-1 to indicate which MCCH and in which MBSFN area is changed. Table 4 below shows an example of the downlink control information. It should be noted that Table 4 is only an example not limitation.

Table 4

The terminal device 110-1 transmits 2015, to the network device 120-1, a request for establishing a MRB associated with the MCCH. In some embodiments, if there is more than one MCCH determined by the terminal device 110-1, the terminal device may request establishing more than one MRB. In other words, one MRB may correspond to one MCCH. In some embodiments, the terminal device 110-1 can receive a paging message associated with the MBS from the network device 120-1. In this situation, the terminal device 110-1 can transmit the request based on the reception of the paging message. Alternatively, the request can be transmitted to the network device 120-1 based on the reception of the MCCH configuration. In this way, the MRB can be configured by the network device 120-1.

The network device 120-1 can transmit 2020 a MRB configuration to the terminal device 110-1. The MRC configuration can indicate an identity of the MRB. In some embodiments, the identity of the MRB can be a reused DRB identity. If the DRB identity is reused, the number of DRB identities can be extended from a first number to a second number. For example, the values of DRB identities can be from 1 to 64. In other words, the number of the DRB identities can be extended from 32 to 64. In this case, if the identity of the MRB is the DRB identity, the identity of the MRB is larger than 32. In this situation, only as an example, the MRB configuration can comprise the parameter “DRB-Identity-v17 :: = INTEGER (33.. 64) . ”

Alternatively, the identity of the MRB can be an identity dedicated to the MRB. For example, the values for MRB identities can be from 1 to 32. In this way, it does not impact the current specification and avoid collision between the DRB scheduling and MRB scheduling. In this case, the MRB configuration can comprise the parameter “MRB-Identity-v17 :: = INTEGER (1.. 32) . ” Table 5 below shows an example of the MRB configuration. It should be noted that Table 5 is only an example not limitation.

Table 5

In some embodiments, the network device 120-1 can configure a PTP bearer as a uni-directional uplink radio link control (RLC) acknowledge mode (AM) bearer. In this case, the MRB configuration can indicate the PTP bearer as a uni-directional uplink radio link control (RLC) acknowledge mode (AM) bearer. For example, as shown in Fig. 3, the multicast session can comprise a service data adaptation protocol (SDAP) layer 310, a PDCP layer 320, a RLC layer 330 and a MAC layer 340. In the RLC layer 330, there is a PTP bearer (entity) 3301 and a PTM bearer (entity) 3302. In the MAC layer 340, there is a dedicated traffic channel (DTCH) 3401 and a MTCH 3402. In this situation, if the PTP bearer 3301 is configured with the MRB, and if the PTP bearer 3302 is only used for PDCP status report and the re-transmission is issued by PDCP layer 320 in the mode of PTM, the network device 120-1 can configure the PTP bearer 3301 as a uni-directional uplink (UL) RLC bearer. Alternatively, if the PTP bearer 3301 is configured with the MRB and if the PTP bearer 3301 is only used for RLC re-transmission, the network device 120-1 can configure the PTP bearer 3301 as uni-directional downlink (DL) RLC bearer. Table 6 below shows an example of the PTP bearer. It should be noted that Table 6 is only an example not limitation.

Table 6

Alternatively or in addition, if the PTP bearer configured with the MRB is used for transmission, the network device 120-1 can configure one or more of the following parameters in the MRB configuration as optional: t-PollRetransmit, poll protocol data unit (pollPDU) , pollByte, or a max retransmission threshold. In this case, the MRB configuration can indicate that at least one of the following is optional: t-PollRetransmit, poll protocol data unit (pollPDU) , pollByte, or a max retransmission threshold. For example, if the PTP bearer 3301 is configured with the MRB, and if the PTP bearer 3301 is only used for re-transmission, then the ul-AM-RLC is mandated to only used to transfer RLC status report. Therefore, the parameters “t-PollRetransmit” , “pollPDU” , “pollByte” and “maxRetxThreshold” should be configured optional. Alternatively or in addition, if the DL PTP bearer is only used for re-transmission, a length of a radio link control sequence number is decreased from a third number of bits to a fourth number of bits. For example, the RLC sequence number (SN) length is can be reduced from 18 bits to 12 bits. It should be noted that the SN length can be any suitable length. Table 7 below shows an example of UM-AM-RLC configuration. It should be noted that Table 7 is only an example not limitation.

Table 7

In some embodiments, if this MRB is associated both PTM and PTP bearers, the network device 120-1 can configure two logical channels, each with the same MRB-ID. Each logical channel has separate RLC configuration and MAC configuration. Table 8 below shows an example of MRB configuration. It should be noted that Table 8 is only an example not limitation.

Table 8

In other embodiments, the network device 120-1 can transmit 2025 a logical channel configuration of a PTP bearer to the terminal device 110-1. For example, if logical channel is a uni-directional logical channel, the logical channel configuration indicates that uplink specific parameters are optional if the PTP bearer is configured with the MRB. Table 9 below shows an example of the logical channel configuration. It should be noted that Table 9 is only an example not limitation.

Table 9

The “UL” field is mandatory present for a logical channel with uplink if it serves DRB. It is optionally present, Need R, for a logical channel with uplink if it serves an SRB or MRB. Otherwise it is absent.

In some embodiments, since the SDAP header and default DRB are unnecessary for MRB, the parameters “sdap-HeaderUL” and “defaultDRB” may not be configured for MRB. Table 10 below shows an example of SDAP configuration. It should be noted that Table 10 is only an example not limitation.

Table 10

In some embodiment, the terminal device 110-1 may suffer radio link failure (RLF) before handover. In some scenarios, a target network device (for example, the network device 120-2) cannot support multicast (PTM) mode, which means the target network device can only setup a DRB with PTP bearer only for the terminal device 110-1. For example, when the terminal device 110-1 is moving to a cell edge, the terminal device 110-1 may suffer RLF before handover. In this case, the terminal device 110-1 performs RRC re-establishment. The terminal device 110-1 can transmit 2030 a RRC reestablishment request to the network device 120-2. When the terminal device 110-1 re-establishes a RRC connection to the network device 120-2, the network device 120-2 can only setup a DRB with PTP bearer only for the terminal device 110-1. In this case, the network device 120-2 can transmit 2035, to the network device 120-1, a request for retrieving a context of the terminal device 110-1 from the network device 120-1. The network device 120-1 can transmit 2040 a UE context response to the network device 120-2. The network device 120-1 can include the MRB information (for example, the MRB configuration shown in Table 8) into the UE context response. In this situation, when the network device 120-2 retrieves the UE context from the network device 120-1, the network device 120-2 may transform the MRB from the network device 120-1 to a DRB in the network device 120-2.

The network device 120-2 can transmit 2045 a RRC reconfiguration for the DRB configuration. The DRB configuration can be associated with the identity of the MRB. For example, the DRB in the RRC reconfiguration may indicate the MRB identity. Table 11 below shows an example of RRC reconfiguration. It should be noted that Table 11 is only an example not limitation.

Table 11

The terminal device 110-1 can transmit 2050 a PDCP status report to the network device 120-2. In this case, the terminal device 110-1 transmits the PDCP status report instead of a SN status transfer by the network device 120-1. The network device 120-2 can determine the MBMS session by the DRB of the PDCP status report to keep the MBS data transmission to the terminal device 110-1. In this way, it ensures the reliability of the MBS data transmission.

In some embodiments, the network device 120-1 can transmit 2055 an indication to the terminal device 110-1. The indication can be used for switching the MRB from PTM mode to the PTP mode. The indication can comprise identity information to indicate the MBS service. For example, the indication can comprise one or more of: a MRB identity, a temporary mobile group identity, a quality of service flow identity, a MBMS area identity, or a MBMS session identity. The indication can also indicate whether a PDCP status report is required. In some embodiments, if the indication indicates that the PDCP status report is required, the terminal device 110-1 can transmit the PDCP status report to the network device 120-1. In this way, it ensures the reliability of the MBS data transmission.

Fig. 4 shows a flowchart of an example method 400 in accordance with an embodiment of the present disclosure. Only for the purpose of illustrations, the method 400 can be implemented at a terminal device 110-1 as shown in Fig. 1.

At block 410, the terminal device 110-1 receives a system information block from the network device 120-1. For example, if a plurality of MCCHs are configured, there can be the plurality of identities for the plurality of MCCHs. The system information block can comprise a list of MCCH configurations. Each of the MCCH configuration may comprises one MCCH identity. In this way, the terminal device 110-1 can differentiate multiple MCCH. In some embodiments, the system information block can comprise a quality of service (QoS) flow identity mapped for the MCCH. The system information block can also comprise a MBS service type. For example, the MBS service type comprises at least one of: MBS service information, MBS session information or a temporary mobile group identity. The terminal device 110-1 can determine a target MCCH configuration from the list of MCCH configurations based on the MBS service type. Alternatively or in addition, the system information block can comprise a multicast broadcast service (MBS) configuration.

In some embodiments, the MBS configuration can indicate a MBS area list where the MCCH configuration is available. Alternatively or in addition, the terminal device 110-1 can receive a multicast traffic channel (MTCH) configuration from the network device 120-1. For example, the MTCH configuration can comprise the identity of the MCCH. Alternatively or in addition, the MTCH configuration can comprise a QoS flow identity to indicate the QoS flow being served.

In other embodiments, the terminal device 110-1 can receive downlink control information (DCI) from the network device 120-1. In some embodiments, the downlink control information can comprise one or more identities of MCCHs which are to be updated. Alternatively or in addition, the downlink control information can indicate one or more multimedia broadcast single frequency network (MBSFN) areas to be updated.

At block 420, the terminal device 110-1 transmits, to the network device 120-1, a request for establishing a MRB associated with the MCCH. In some embodiments, if there is more than one MCCH determined by the terminal device 110-1, the terminal device may request establishing more than one MRB. In other words, one MRB may correspond to one MCCH. In some embodiments, the terminal device 110-1 can receive a paging message associated with the MBS from the network device 120-1. In this situation, the terminal device 110-1 can transmit the request based on the reception of the paging message. Alternatively, the request can be transmitted to the network device 120-1 based on the reception of the MCCH configuration. In this way, the MRB can be configured by the network device 120-1.

The terminal device 110-1 can receive a MRB configuration from the network device 120-1. The MRC configuration can indicate an identity of the MRB. In some embodiments, the identity of the MRB can be a reused DRB identity. If the DRB identity is reused, the number of DRB identities can be extended from a first number to a second number. For example, the values of DRB identities can be from 1 to 64. In other words, the number of the DRB identities can be extended from 32 to 64. In this situation, only as an example, the MRB configuration can comprise the parameter “DRB-Identity-v17 :: =INTEGER (33.. 64) . ”

Alternatively, the identity of the MRB can be an identity dedicated to the MRB. For example, the values for MRB identities can be from 1 to 32. In this way, it does not impact the current specification and avoid collision between the DRB scheduling and MRB scheduling. In this case, if the identity of the MRB is the DRB identity, the identity of the MRB is larger than 32. In this case, the MRB configuration can comprise the parameter “MRB-Identity-v17 :: = INTEGER (1.. 32) . ”

In some embodiments, the MRB configuration can indicate the PTP bearer as a uni-directional uplink radio link control (RLC) acknowledge mode (AM) bearer. In this situation, if the PTP bearer is configured with the MRB, and if the PTP bearer is only used for PDCP status report and the re-transmission is issued by PDCP layer in the mode of PTM, the network device can configure the PTP bearer 3301 as a uni-directional uplink (UL) RLC bearer. Alternatively, if the PTP bearer is configured with the MRB and if the PTP bearer is only used for RLC re-transmission, the network device 120-1 can configure the PTP bearer 3301 as uni-directional downlink (DL) RLC bearer.

Alternatively or in addition, if the PTP bearer configured with the MRB is used for transmission, the MRB configuration can indicate that at least one of the following is optional: t-PollRetransmit, poll protocol data unit (pollPDU) , pollByte, or a max retransmission threshold. Alternatively or in addition, if the DL PTP bearer is only used for re-transmission, a length of a radio link control sequence number is a default/predetermined number. In other words, the RLC sequence number (SN) length can be a fixed value and the network device 120-2 does not need to configure the RLC SN length. For example, the RLC SN length is can be fixed to 12 bits. It should be noted that the SN length can be any suitable default length.

In other embodiments, the terminal device 110-1 can receive a logical channel configuration of a PTP bearer from the network device 120-1. For example, if logical channel is a uni-directional logical channel, the logical channel configuration indicates that uplink specific parameters are optional if the PTP bearer is configured with the MRB. In some embodiments, since the SDAP header and default DRB are unnecessary for MRB, the parameters “sdap-HeaderUL” and “defaultDRB” may not be configured for MRB.

In some embodiment, the terminal device 110-1 may suffer radio link failure (RLF) before handover. In some scenarios, a target network device (for example, the network device 120-2) cannot support multicast (PTM) mode, which means the target network device can only setup a DRB with PTP bearer only for the terminal device 110-1. For example, when the terminal device 110-1is moving to a cell edge, the terminal device 110-1 may suffer RLF before handover. In this case, the terminal device 110-1 performs RRC re-establishment. The terminal device 110-1 can transmit a RRC reestablishment request to the network device 120-2. The terminal device 110-1 can receive a RRC reconfiguration for the DRB configuration from the network device 120-2. The DRB configuration can be associated with the identity of the MRB. For example, the DRB in the RRC reconfiguration may indicate the MRB identity. The terminal device 110-1 can transmit a PDCP status report to the network device 120-2. In this case, the terminal device 110-1 transmits the PDCP status report instead of a SN status transfer by the network device 120-1. The network device 120-2 can determine the MBMS session by the DRB of the PDCP status report to keep the MBS data transmission to the terminal device 110-1. In this way, it ensures the reliability of the MBS data transmission.

In some embodiments, the terminal device 110-1 can receive an indication from the network device 120-1. The indication can be used for switching the MRB from PTM mode to the PTP mode. The indication can comprise identity information to indicate the MBS service. For example, the indication can comprise one or more of: a MRB identity, a temporary mobile group identity, a quality of service flow identity, a MBMS area identity, or a MBMS session identity. The indication can also indicate whether a PDCP status report is required. In some embodiments, if the indication indicates that the PDCP status report is required, the terminal device 110-1 can transmit the PDCP status report to the network device 120-1. In this way, it ensures the reliability of the MBS data transmission.

Fig. 5 shows a flowchart of an example method 500 in accordance with an embodiment of the present disclosure. Only for the purpose of illustrations, the method 500 can be implemented at a network device 120-1 as shown in Fig. 1.

At block 510, the network device 120-1 transmits a system information block to the terminal device 110-1. For example, if a plurality of MCCHs are configured, there can be the plurality of identities for the plurality of MCCHs. In this case, the identity can be selected from the plurality of identities. In this way, the terminal device 110-1 can differentiate multiple MCCH. In some embodiments, the system information block can comprise a quality of service (QoS) flow identity mapped for the MCCH. Alternatively or in addition, the system information block can comprise a multicast broadcast service (MBS) configuration.

In some embodiments, the MBS configuration can indicate a MBS area list where the MCCH configuration is available. Alternatively or in addition, the network device 120-1 can transmit a multicast traffic channel (MTCH) configuration to the terminal device 110-1. For example, the MTCH configuration can comprise the identity of the MCCH. Alternatively or in addition, the MTCH configuration can comprise a QoS flow identity to indicate the QoS flow being served.

The network device 120-1 can transmit downlink control information (DCI) to the terminal device 110-1. In some embodiments, the downlink control information can comprise the identity of the MCCH which is to be updated. Alternatively or in addition, the downlink control information can indicate a multimedia broadcast single frequency network (MBSFN) area to be updated. In LTE MBMS, the network device 120-1 can send DCI format 1C to update the MCCH. In DCI 1C, information for MCCH change notification can be used to update the MCCH. For example, the information for MCCH change notification can be 8 bits bitmap, which is to indicate which MBSFN area is updated. In some embodiments, a MCCH list can be included in the DCI in order to allow the network device 120-1 to indicate which MCCH and in which MBSFN area is changed.

At block 520, the network device 120-1 receives, from the terminal device 110-1, a request for establishing a MRB associated with the MCCH. In some embodiments, the terminal device 110-1 can receive a paging message associated with the MBS from the network device 120-1. In this situation, the terminal device 110-1 can transmit the request based on the reception of the paging message. Alternatively, the request can be transmitted to the network device 120-1 based on the reception of the MCCH configuration. In this way, the MRB can be configured by the network device 120-1.

The network device 120-1 can transmit a MRB configuration to the terminal device 110-1. The MRC configuration can indicate an identity of the MRB. In some embodiments, the identity of the MRB can be a reused DRB identity. If the DRB identity is reused, the number of DRB identities can be extended from a first number to a second number. For example, the values of DRB identities can be from 1 to 64. In other words, the number of the DRB identities can be extended from 32 to 64. In this situation, only as an example, the MRB configuration can comprise the parameter “DRB-Identity-v17 :: =INTEGER (33.. 64) . ”

Alternatively, the identity of the MRB can be an identity dedicated to the MRB. For example, the values for MRB identities can be from 1 to 32. In this way, it does not impact the current specification and avoid collision between the DRB scheduling and MRB scheduling. In this case, the MRB configuration can comprise the parameter “MRB-Identity-v17 :: = INTEGER (1.. 32) . ”

In some embodiments, the network device 120-1 can configure a PTP bearer as a uni-directional uplink radio link control (RLC) acknowledge mode (AM) bearer. In this case, the MRB configuration can indicate the PTP bearer as a uni-directional uplink radio link control (RLC) acknowledge mode (AM) bearer.

Alternatively or in addition, if the PTP bearer configured with the MRB is used for transmission, the network device 120-1 can configure one or more of the following parameters in the MRB configuration as optional: t-PollRetransmit, poll protocol data unit (pollPDU) , pollByte, or a max retransmission threshold. In this case, the MRB configuration can indicate that at least one of the following is optional: t-PollRetransmit, poll protocol data unit (pollPDU) , pollByte, or a max retransmission threshold.

In some embodiments, if this MRB is associated both PTM and PTP bearers, the network device 120-1 can configure two logical channels, each with the same MRB-ID. Each logical channel has separate RLC configuration and MAC configuration.

In other embodiments, the network device 120-1 can transmit a logical channel configuration of a PTP bearer to the terminal device 110-1. For example, if logical channel is a uni-directional logical channel, the logical channel configuration indicates that uplink specific parameters are optional if the PTP bearer is configured with the MRB. In some embodiments, since the SDAP header and default DRB are unnecessary for MRB, the parameters “sdap-HeaderUL” and “defaultDRB” may not be configured for MRB.

When the terminal device 110-1 re-establishes a RRC connection to the network device 120-2, the network device 120-2 can only setup a DRB with PTP bearer only for the terminal device 110-1. In this case, the network device 120-1 can receive, from the network device 120-2, a request for retrieving a context of the terminal device 110-1 from the network device 120-1. The network device 120-1 can transmit a UE context response to the network device 120-2. The network device 120-1 can include the MRB information (for example, the MRB configuration shown in Table 8) into the UE context response.

In some embodiments, the network device 120-1 can transmit an indication to the terminal device 110-1. The indication can be used for switching the MRB from PTM mode to the PTP mode. The indication can comprise identity information to indicate the MBS service. For example, the indication can comprise one or more of: a MRB identity, a temporary mobile group identity, a quality of service flow identity, a MBMS area identity, or a MBMS session identity. The indication can also indicate whether a PDCP status report is required. In some embodiments, if the indication indicates that the PDCP status report is required, the terminal device 110-1 can transmit the PDCP status report to the network device 120-1. In this way, it ensures the reliability of the MBS data transmission.

Fig. 6 shows a flowchart of an example method 600 in accordance with an embodiment of the present disclosure. Only for the purpose of illustrations, the method 600 can be implemented at a network device 120-2 as shown in Fig. 1.

At block 610, the network device 120-2 receives a radio resource control (RRC) reestablishment request from the terminal device 110-1. When the terminal device 110-1 re-establishes a RRC connection to the network device 120-2, the network device 120-2 can only setup a DRB with PTP bearer only for the terminal device 110-1.

At block 620, the network device 120-2 transmits, to the network device 120-1, a request for retrieving a context of the terminal device 110-1 from the network device 120-1.

At block 630, the network device 120-2 receives a UE context response from the network device 120-1. The MRB information (for example, the MRB configuration shown in Table 8) can be included in the UE context response. In this situation, when the network device 120-2 retrieves the UE context from the network device 120-1, the network device 120-2 may transform the MRB from the network device 120-1 to a DRB in the network device 120-2.

At block 640, the network device 120-2 transmits a RRC reconfiguration for the DRB configuration. The DRB configuration can be associated with the identity of the MRB. For example, the DRB in the RRC reconfiguration may indicate the MRB identity.

In some embodiments, the network device 120-2 can receive a PDCP status report from the terminal device 110-1. In this case, the terminal device 110-1 transmits the PDCP status report instead of a SN status transfer by the network device 120-1. The network device 120-2 can determine the MBMS session by the DRB of the PDCP status report to keep the MBS data transmission to the terminal device 110-1. In this way, it ensures the reliability of the MBS data transmission.

In some embodiments, a terminal device comprises circuitry configured to receive, from a network device, a system information block for a multimedia broadcast multicast service (MBMS) control channel (MCCH) configuration, the system information block indicating an identity of a MCCH; transmit , to the network device, a request for establishing a multicast radio bearer (MRB) associated with the MCCH.

In some embodiments, the system information block indicates a list of MCCH configurations, and the device comprises circuitry configured to determine one or more target MCCH configurations from the list of MCCH configurations based on a multicast broadcast service (MBS) service type.

In some embodiments, the device comprises circuitry configured to receive the system information for the MCCH configuration by receiving the system information comprising at least one of: a quality of service (QoS) flow identity mapped for the MCCH, a MBS service type, wherein the MBS service type comprises at least one of: MBS service information, MBS session information or a temporary mobile group identity, or a multicast broadcast service (MBS) configuration, and wherein the MBS configuration indicates a MBS area list where the MCCH configuration is available.

In some embodiments, the device comprises circuitry configured to receive, from the network device, a multicast traffic channel (MTCH) configuration comprising: the identity of the MCCH, and a quality of service (QoS) flow identity to indicate the QoS flow being served.

In some embodiments, the device comprises circuitry configured to receive, from the network device, downlink control information indicating the identity of the MCCH which is to be updated and a multimedia broadcast single frequency network (MBSFN) area to be updated.

In some embodiments, the device comprises circuitry configured to receive, from the network device, a MRB configuration one or more identities of MCCHs which are to be updated and one or more multimedia broadcast single frequency network (MBSFN) areas to be updated.

In some embodiments, in accordance with a determination that the identity of the MRB is the DRB identity, the identity of the MRB is larger than 32.

In some embodiments, wherein the MRB configuration indicates that a point to point (PTP) bearer configured with the MRB is auni-directional uplink radio link control (RLC) acknowledge mode (AM) bearer; or wherein the MRB configuration indicates that the PTP bearer configured with the MRB is an unidirectional downlink RLC un-acknowledge mode (UM) bearer.

In some embodiments, wherein in accordance with a determination that a point to point (PTP) bearer configured with the MRB is used for retransmission, the MRB configuration indicates that at least one of the following parameters is optional: t-PollRetransmit, poll protocol data unit (pollPDU) , pollByte, or a max retransmission threshold.

In some embodiments, wherein in accordance with a determination that a point to point (PTP) bearer configured with the MRB is used for retransmission, a length of a radio link control sequence number is a default number.

In some embodiments, the device comprises circuitry configured to receive, from the network device, a logical channel configuration of a point to point (PTP) bearer; and wherein in accordance with a determination that that a logical channel is a uni-directional logical channel, the logical channel configuration indicates that uplink specific parameters is optional if the PTP bearer is configured with the MRB.

In some embodiments, wherein at least one of the following is absent in the MRB configuration: a service data adaptation protocol (SDAP) header, or a default data radio bearer.

In some embodiments, the device comprises circuitry configured to transmit, to another network device, a radio resource control (RRC) reestablishment request; receive, from the other network device, a RRC reconfiguration for a data radio bearer (DRB) configuration, the DRB configuration associated with an identity of the MRB; and transmit, to the other network device, a packet data convergence protocol (PDCP) status report.

In some embodiments, the device comprises circuitry configured to receive, from the network device, an indication for switching the MRB from a point to multi-point (PTM) mode to a point to point (PTP) mode; and wherein the indication indicating at least one of: a MRB identity, a temporary mobile group identity, a quality of service flow identity, a MBMS area identity, a MBMS session identity, or whether a packet data convergence protocol (PDCP) status report is required.

In some embodiments, the device comprises circuitry configured to in accordance with a determination that the indication indicates that the PDCP status report is required, transmit the PDCP status report to the network device.

In some embodiments, a network device comprises circuitry configured to transmit, to a terminal device, a system information block for a multimedia broadcast multicast service (MBMS) control channel (MCCH) configuration, the system information block indicating an identity of a MCCH; and receive, from the terminal device, a request for establishing a multicast radio bearer (MRB) associated with the MCCH.

In some embodiments, the network device comprises circuitry configured to transmit the system information for the MCCH configuration by transmitting the system information comprising at least one of: a quality of service (QoS) flow identity mapped for the MCCH, a MBS service type, wherein the MBS service type comprises at least one of: MBS service information, MBS session information or a temporary mobile group identity, or a multicast broadcast service (MBS) configuration, and wherein the MBS configuration indicates a MBS area list where the MCCH configuration is available.

In some embodiments, the network device comprises circuitry configured to transmit to the terminal device, a multicast traffic channel (MTCH) configuration comprising: the identity of the MCCH to associate with the MCCH configuration, and a quality of service (QoS) flow identity to indicate the QoS flow being served.

In some embodiments, the network device comprises circuitry configured to transmit. to the terminal device, downlink control information indicating the identity of the MCCH which is to be updated and a multimedia broadcast single frequency network (MBSFN) area to be updated.

In some embodiments, the network device comprises circuitry configured to transmit, to the terminal device, a MRB configuration indicating an identity of the MRB, and wherein the identity of the MRB is a reused data radio bearer (DRB) identity or an identity dedicated to the MRB.

In some embodiments, wherein in accordance with a determination that the identity of the MRB is the reused DRB identity, the identity of the MRB is larger than 32.

In some embodiments, wherein the MRB configuration indicates that a point to point (PTP) bearer configured with the MRB is an uni-directional uplink radio link control (RLC) acknowledge mode (AM) bearer; or wherein the MRB configuration indicates that the PTP bearer configured with the MRB is an unidirectional downlink RLC un-acknowledge mode (UM) bearer.

In some embodiments, the network device comprises circuitry configured to in accordance with a determination that a point to point (PTP) bearer configured with the MRB is used for retransmission, configure at least one of the following parameter in the MRB configuration as optional: t-PollRetransmit, poll protocol data unit (pollPDU) , pollByte, or a max retransmission threshold.

In some embodiments, the network device comprises circuitry configured to in accordance with a determination that that a logical channel of a point to point (PTP) bearer is a uni-directional logical channel, configure uplink specific parameters in a logical channel configuration as optional if the PTP bearer is configured with the MRB; and transmit, to the terminal device, the logical channel configuration.

In some embodiments, , wherein at least one of the following is absent in the MRB configuration: a service data adaptation protocol (SDAP) header, or a default data radio bearer.

In some embodiments, the network device comprises circuitry configured to receive, from another network device, a request for retrieving a user equipment (UE) context; and transmit, to the other network device, a UE context response indicating the MRB configuration.

In some embodiments, the network device comprises circuitry configured to transmit, to the terminal device, an indication for switching the MRB from a point to multi-point (PTM) mode to a point to point (PTP) mode; and wherein the indication indicating at least one of: a MRB identity, a temporary mobile group identity, a quality of service flow identity, a MBMS area identity, a MBMS session identity, or whether a packet data convergence protocol (PDCP) status report is required.

In some embodiments, the network device comprises circuitry configured to in accordance with a determination that the indication indicates that the PDCP status report is required, receive the PDCP status report from the terminal device.

In some embodiments, a first network device comprises circuitry configured to receive, from a terminal device, a radio resource control (RRC) reestablishment request; transmit, at the first network device and to a second network device, a request for retrieving a user equipment (UE) context; receive, from the second network device, a UE context response indicating a configuration of a multicast radio bearer (MRB) which is configured at the terminal device; and transmit, to the terminal device, a RRC reconfiguration for a data radio bearer (DRB) configuration, the DRB reconfiguration associated with an identity of the MRB.

In some embodiments, a first network device comprises circuitry configured to receive, from the terminal device, a packet data convergence protocol (PDCP) status report; determine a multimedia broadcast multicast service (MBMS) session based on the DRB of the PDCP status report; and perform a multicast broadcast service (MBS) data transmission on the DRB.

Fig. 7 is a simplified block diagram of a device 700 that is suitable for implementing embodiments of the present disclosure. The device 700 can be considered as a further example implementation of the network device 120, or the terminal device 110 as shown in Fig. 1. Accordingly, the device 700 can be implemented at or as at least a part of the terminal device 110, or the network device 120.

As shown, the device 700 includes a processor 710, a memory 720 coupled to the processor 710, a suitable transmitter (TX) and receiver (RX) 740 coupled to the processor 710, and a communication interface coupled to the TX/RX 740. The memory 710 stores at least a part of a program 730. The TX/RX 740 is for bidirectional communications. The TX/RX 740 has at least one antenna to facilitate communication, though in practice an Access Node mentioned in this application may have several ones. The communication interface may represent any interface that is necessary for communication with other network elements, such as X2 interface for bidirectional communications between eNBs, S1 interface for communication between a Mobility Management Entity (MME) /Serving Gateway (S-GW) and the eNB, Un interface for communication between the eNB and a relay node (RN) , or Uu interface for communication between the eNB and a terminal device.

The program 730 is assumed to include program instructions that, when executed by the associated processor 710, enable the device 700 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to Figs. 2 to 6. The embodiments herein may be implemented by computer software executable by the processor 710 of the device 700, or by hardware, or by a combination of software and hardware. The processor 710 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 710 and memory 720 may form processing means adapted to implement various embodiments of the present disclosure.

The memory 720 may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory 720 is shown in the device 700, there may be several physically distinct memory modules in the device 700. The processor 710 may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 700 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or method as described above with reference to Figs. 2 to 10. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

The above program code may be embodied on a machine readable medium, which may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

A communication method, comprising:

receiving, at a terminal device and from a network device, a system information block for a multimedia broadcast multicast service (MBMS) control channel (MCCH) configuration, the system information block indicating an identity of a MCCH; and

transmitting, to the network device, a request for establishing a multicast radio bearer (MRB) associated with the MCCH.
The method of claim 1, wherein the system information block indicates a list of MCCH configurations, and wherein the method further comprising:

determining one or more target MCCH configurations from the list of MCCH configurations based on a multicast broadcast service (MBS) service type.
The method of claim 1, wherein receiving the system information block for the MCCH configuration comprises:

receiving the system information block comprising at least one of:

a quality of service (QoS) flow identity mapped for the MCCH,

a multicast broadcast service (MBS) configuration, wherein the MBS configuration indicates a MBS area list where the MCCH configuration is available, or

a MBS service type, wherein the MBS service type comprises at least one of: MBS service information, MBS session information or a temporary mobile group identity.
The method of claim 1, further comprising:

receiving, from the network device, a multicast traffic channel (MTCH) configuration comprising:

the identity of the MCCH, and

a quality of service (QoS) flow identity to indicate the QoS flow being served.
The method of claim 1, further comprising:

receiving, from the network device, downlink control information indicating the one or more identities of MCCHs which are to be updated and one or more multimedia broadcast single frequency network (MBSFN) areas to be updated.
The method of claim 1, further comprising:

receiving, from the network device, a MRB configuration indicating an identity of the MRB, and

wherein the identity of the MRB is a data radio bearer (DRB) identity or an identity dedicated to the MRB.
The method of claim 6, wherein in accordance with a determination that the identity of the MRB is the DRB identity, the identity of the MRB is larger than 32.
The method of claim 6, wherein the MRB configuration indicates that a point to point (PTP) bearer configured with the MRB is an uni-directional uplink radio link control (RLC) acknowledge mode (AM) bearer.
The method of claim 6, wherein in accordance with a determination that a point to point (PTP) bearer configured with the MRB is used for retransmission, the MRB configuration indicates that at least one of the following parameters is optional:

t-PollRetransmit,

poll protocol data unit (pollPDU) ,

pollByte, or

a max retransmission threshold.
The method of claim 1, wherein in accordance with a determination that a point to point (PTP) bearer configured with the MRB is used for retransmission, a length of a radio link control sequence number is a default number.
The method of claim 1, further comprising:

receiving, from the network device, a logical channel configuration of a point to point (PTP) bearer; and

wherein in accordance with a determination that that a logical channel is a uni-directional logical channel, the logical channel configuration indicates that uplink specific parameters is optional if the PTP bearer is configured with the MRB.
The method of claim 7, wherein at least one of the following is absent in the MRB configuration:

a service data adaptation protocol (SDAP) header, or

a default data radio bearer.
The method of claim 1, further comprising:

transmitting, to another network device, a radio resource control (RRC) reestablishment request;

receiving, from the other network device, a RRC reconfiguration for a data radio bearer (DRB) configuration, the DRB configuration associated with an identity of the MRB; and

transmitting, to the other network device, a packet data convergence protocol (PDCP) status report.
The method of claim 1, further comprising:

receiving, from the network device, an indication for switching the MRB from a point to multi-point (PTM) mode to a point to point (PTP) mode; and

wherein the indication indicating at least one of:

a MRB identity,

a temporary mobile group identity,

a quality of service flow identity,

a MBMS area identity,

a MBMS session identity, or

whether a packet data convergence protocol (PDCP) status report is required.
The method of claim 14, further comprising:

in accordance with a determination that the indication indicates that the PDCP status report is required, transmitting the PDCP status report to the network device.
A communication method, comprising:

transmitting, at a network device and to a terminal device, a system information block for a multimedia broadcast multicast service (MBMS) control channel (MCCH) configuration, the system information block indicating an identity of a MCCH; and

receiving, from the terminal device, a request for establishing a multicast radio bearer (MRB) associated with the MCCH.
The method of claim 16, wherein the system information block indicates a list of MCCH configurations.
The method of claim 16, wherein transmitting the system information for the MCCH configuration comprises:

transmitting the system information comprising at least one of:

a quality of service (QoS) flow identity mapped for the MCCH,

a multicast broadcast service (MBS) configuration, wherein the MBS configuration indicates a MBS area list where the MCCH configuration is available, or

a MBS service type, wherein the MBS service type comprises at least one of: MBS service information, MBS session information or a temporary mobile group identity.
The method of claim 16, further comprising:

transmitting, to the terminal device, a multicast traffic channel (MTCH) configuration comprising:

the identity of the MCCH, and

a quality of service (QoS) flow identity to indicate the QoS flow being served.
The method of claim 16, further comprising:

transmitting, to the terminal device, downlink control information indicating the one or more identities of MCCHs which are to be updated and one or more multimedia broadcast single frequency network (MBSFN) areas to be updated.
The method of claim 16, further comprising:

transmitting, to the terminal device, a MRB configuration indicating an identity of the MRB, and

wherein the identity of the MRB is a data radio bearer (DRB) identity or an identity dedicated to the MRB.
The method of claim 21, wherein in accordance with a determination that the identity of the MRB is the reused DRB identity, the identity of the MRB is larger than 32.
The method of claim 16, wherein the MRB configuration indicates that a point to point (PTP) bearer configured with the MRB is a uni-directional uplink radio link control (RLC) acknowledge mode (AM) bearer.
The method of claim 16, further comprising:

in accordance with a determination that a point to point (PTP) bearer configured with the MRB is used for retransmission, configuring at least one of the following parameter in the MRB configuration as optional:

t-PollRetransmit,

poll protocol data unit (pollPDU) ,

pollByte, or

a max retransmission threshold.
The method of claim 16, wherein in accordance with a determination that a point to point (PTP) bearer configured with the MRB is used for retransmission, a length of a radio link control sequence number is a default number.
The method of claim 16, further comprising:

in accordance with a determination that that a logical channel of a point to point (PTP) bearer is a uni-directional logical channel, configuring uplink specific parameters in a logical channel configuration as optional if the PTP bearer is configured with the MRB; and

transmitting, to the terminal device, the logical channel configuration.
The method of claim 16, wherein at least one of the following is absent in the MRB configuration:

a service data adaptation protocol (SDAP) header, or

a default data radio bearer.
The method of claim 16, further comprising:

receiving, from another network device, a request for retrieving a user equipment (UE) context; and

transmitting, to the other network device, a UE context response indicating the MRB configuration.
The method of claim 16, further comprising:

transmitting, to the terminal device, an indication for switching the MRB from a point to multi-point (PTM) mode to a point to point (PTP) mode; and

wherein the indication indicating at least one of:

a MRB identity,

a temporary mobile group identity,

a quality of service flow identity,

a MBMS area identity,

a MBMS session identity, or

whether a packet data convergence protocol (PDCP) status report is required.
The method of claim 29, further comprising:

in accordance with a determination that the indication indicates that the PDCP status report is required, receiving the PDCP status report from the terminal device.
A communication method,

receiving, at a first network device and from a terminal device, a radio resource control (RRC) reestablishment request;

transmitting, at the first network device and to a second network device, a request for retrieving a user equipment (UE) context;

receiving, from the second network device, a UE context response indicating a configuration of a multicast radio bearer (MRB) which is configured at the terminal device; and

transmitting, to the terminal device, a RRC reconfiguration for a data radio bearer (DRB) configuration, the DRB reconfiguration associated with an identity of the MRB.
The method of claim 31, further comprising:

receiving, from the terminal device, a packet data convergence protocol (PDCP) status report;

determining a multimedia broadcast multicast service (MBMS) session based on the DRB of the PDCP status report; and

performing a multicast broadcast service (MBS) data transmission on the DRB.
A terminal device comprising:

circuitry, configured to perform the method according to any of claims 1 to 16.
A network device comprising:

circuitry, configured to perform the method according to any of claims 16 to 30 or 31 to 32.
A computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method according to any of claims 1 to 15, or 16 to 30 or 31 to 32.