WO2022135400A1

WO2022135400A1 - Method and user equipment for handling reception of multicast-broadcast service

Info

Publication number: WO2022135400A1
Application number: PCT/CN2021/140103
Authority: WO
Inventors: Hengli CHIN; Chiahung Lin; Hungchen CHEN; Yunglan TSENG
Original assignee: FG Innovation Co Ltd
Current assignee: FG Innovation Co Ltd
Priority date: 2020-12-21
Filing date: 2021-12-21
Publication date: 2022-06-30
Anticipated expiration: 2023-06-21

Abstract

A method and a user equipment (UE) for handling reception of Multicast-Broadcast Service (MBS) is provided. The method includes: receiving at least one of a first downlink (DL) assignment and a second DL assignment for scheduling a first MBS corresponding to a first MBS Radio Bearer (MRB), the first DL assignment being associated with a first Group-Radio Network Temporary Identifier (G-RNTI) for the first MRB and the second DL assignment being associated with a Cell-Radio Network Temporary Identifier (C-RNTI) of the UE; receiving data of the first MBS based on the at least one of the first DL assignment and the second DL assignment; receiving a switching indication from a network; determining, based on the switching indication, whether to stop or start receiving the at least one of the first DL assignment and the second DL assignment.

Description

METHOD AND USER EQUIPMENT FOR HANDLING RECEPTION OF MULTICAST-BROADCAST SERVICE

CROSS-REFERENCE TO RELATED APPLICATION (S)

The present disclosure claims the benefit of and priority to U.S. Provisional Patent Application Serial No. 63/128,695, filed on December 21, 2020, entitled “METHOD AND APPARATUS TO HANDLE RECEPTION OF NR BROADCAST MULTICAST SERVICE” ( “the ’695 provisional” ) . The contents of the ’695 provisional are hereby incorporated fully by reference into the present disclosure for all purposes.

FIELD

The present disclosure is related to wireless communication, and more particularly, to a method and a user equipment (UE) for handling reception of Multicast-Broadcast Service (MBS) in next generation wireless communication networks.

BACKGROUND

Various efforts have been made to improve different aspects of wireless communication for cellular wireless communication systems, such as 5G New Radio (NR) , by improving data rate, latency, reliability, and mobility. The 5G NR system is designed to provide flexibility and configurability to optimize the network services and types, accommodating various use cases such as enhanced Mobile Broadband (eMBB) , massive Machine-Type Communication (mMTC) , and Ultra-Reliable and Low-Latency Communication (URLLC) . However, as the demand for radio access continues to increase, there exists a need for further improvements in the art.

SUMMARY

The present disclosure is related to a method and a user equipment for handling reception of Multicast-Broadcast Service (MBS) in the next generation wireless communication networks.

In a first aspect of the present disclosure, a method performed by a user equipment (UE) for handling reception of MBS is provided. The method includes: receiving at least one of a first downlink (DL) assignment and a second DL assignment for scheduling a first MBS corresponding to a first MBS Radio Bearer (MRB) , the first DL assignment being associated with a first Group-Radio Network Temporary Identifier (G-RNTI) for the first MRB and the second DL assignment being associated with a Cell-Radio Network Temporary Identifier (C-RNTI) of the UE; receiving data of the first MBS based on the at least one of the first DL assignment and the second DL assignment; receiving a switching indication from a network; determining, based on the switching indication, whether to stop or start receiving the at least one of the first DL assignment and the second DL assignment.

In an implementation of the first aspect of the present disclosure, the method further includes: determining, based on the switching indication, whether to stop or start monitoring at least one of a first search space for receiving the first DL assignment and a second search space for receiving the second DL assignment.

In an implementation of the first aspect of the present disclosure, the method further includes: transmitting an uplink (UL) feedback in response to reception of the switching indication.

In an implementation of the first aspect of the present disclosure, the UL feedback is a Packet Data Convergence Protocol (PDCP) status report, and the PDCP status report is transmitted from a PDCP entity of the UE that corresponds to the first MRB.

In an implementation of the first aspect of the present disclosure, the switching indication is a Radio Resource Control (RRC) message, a Medium Access Control (MAC) Control Element (CE) , or Downlink Control Information (DCI) .

In an implementation of the first aspect of the present disclosure, the first MRB corresponds to a Packet Data Convergence Protocol (PDCP) entity and at least one of a first Radio Link Control (RLC) entity configured for point-to-multipoint (PTM) transmission and a second RLC entity configured for point-to-point (PTP) transmission, and the method further includes: stopping receiving the first DL assignment in a case that the first MRB corresponds to the PDCP entity and the first RLC entity and the second RLC entity, and the switching indication indicates the first RLC entity is released; and starting receiving the first DL assignment in a case that the first MRB corresponds to the PDCP entity and the second RLC entity, and the switching indication indicates the first RLC entity is configured for the first MRB.

In an implementation of the first aspect of the present disclosure, the method further includes: starting receiving the first DL assignment in a case that only the second DL assignment is received, and the switching indication indicates the transmission mode of the first MBS is switched; and starting receiving the second DL assignment in a case that only the first DL assignment is received, and the switching indication indicates the transmission mode of the first MBS is switched.

In an implementation of the first aspect of the present disclosure, the method further includes: receiving at least one of a third DL assignment and a fourth DL assignment for scheduling a second MBS corresponding to a second MRB, the third DL assignment being associated with a second G-RNTI for the second MRB and the fourth DL assignment being associated with the C-RNTI of the UE; receiving data of the second MBS based on the at least one of the third DL assignment and the fourth DL assignment; determining, based on the switching indication, whether to stop or start receiving the at least one of the third DL assignment and the fourth DL assignment.

In an implementation of the first aspect of the present disclosure, the first MRB corresponds to a first Packet Data Convergence Protocol (PDCP) entity and at least one of a first Radio Link Control (RLC) entity configured for point-to-multipoint (PTM) transmission and a second RLC entity configured for point-to-point (PTP) transmission, and the second MRB corresponds to a second PDCP entity and at least one of a third RLC entity configured for PTM transmission and a fourth RLC entity configured for PTP transmission, and the method further includes: stopping receiving the first DL assignment and the third DL assignment in a case that the first MRB corresponds to the first PDCP entity and the first RLC entity and the second RLC entity, the second MRB corresponds to the second PDCP entity and the third RLC entity and the fourth RLC entity, and the switching indication indicates the first RLC entity and the third RLC entity are released, and starting receiving the first DL assignment and the third DL assignment in a case that the first MRB corresponds to the first PDCP entity and the second RLC entity, the second MRB corresponds to the second PDCP entity and the fourth RLC entity, and the switching indication indicates the first RLC entity is configured for the first MRB and the third RLC entity is configured for the second MRB.

In a second aspect of the present disclosure, a UE for handling reception of MBS is provided. The UE includes a processor; and a memory coupled to the processor, wherein the memory stores a computer-executable program that when executed by the processor, causes the processor to: receive at least one of a first DL assignment and a second DL assignment for scheduling a first MBS corresponding to a first MRB, the first DL assignment being associated with a first G-RNTI for the first MRB and the second DL assignment being associated with a C-RNTI of the UE; receive data of the first MBS based on the at least one of the first DL assignment and the second DL assignment; receive a switching indication from a network; and determine, based on the switching indication, whether to stop or start receiving the at least one of the first DL assignment and the second DL assignment.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the disclosure are best understood from the following detailed disclosure when read with the accompanying drawings. Various features are not drawn to scale. Dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a schematic diagram illustrating various delivery methods for delivering MBS traffic in the 5GS according to an example implementation of the present disclosure.

FIG. 2 is a schematic diagram illustrating that the PDCP layer (e.g., PDCP entity) of the BS/UE as an anchor to support dynamic switch according to an example implementation of the present disclosure.

FIG. 3 is a dynamic switch procedure of MBS delivery according to an example implementation of the present disclosure.

FIG. 4 is a flowchart illustrating a method performed by a UE for handling reception of Multicast-Broadcast Service (MBS) according to an example implementation of the present disclosure.

FIG. 5 is a flowchart illustrating a method performed by a UE for handling reception of Multicast-Broadcast Service (MBS) according to another example implementation of the present disclosure.

FIG. 6 is a block diagram illustrating a node for wireless communication according to an example implementation of the present disclosure.

DESCRIPTION

The acronyms in the present application are defined as follows and unless otherwise specified, the acronyms have the following meanings:

Acronym Full name

3GPP 3 ^rd Generation Partnership Project

5G 5 ^th Generation

ACK Acknowledgement

AM Acknowledgement mode

ARQ Automatic Repeat Request

BCCH Broadcast Control Channel

BCH Broadcast Channel

BL Bandwidth reduced Low complexity

BS Base Station

BSR Buffer Status Report

BWP Bandwidth Part

CA Carrier Aggregation

CC Component Carrier

CCCH Common Control Channel

CE Control Element

CG Cell Group

CN Core Network

CORESET Control Resource Set

C-RNTI Cell-Radio Network Temporary Identifier

CRC Cyclic Redundancy Check

DC Dual Connectivity

DCI Downlink Control Information

DL Downlink

DL-SCH Downlink Shared Channel

DRB Data Radio Bearer

eNB Evolved Node B

E-UTRA Evolved Universal Terrestrial Radio Access

E-UTRAN Evolved Universal Terrestrial Radio Access Network

gNB Next Generation Node B

G-RNTI Group Radio Network Temporary Identifier

HARQ Hybrid Automatic Repeat Request

ID Identity

IE Information Element

L1 Layer 1

L2 Layer 2

LCG Logical Channel Group

LCH Logical Channel

LCID Logical Channel Identity

LTE Long Term Evolution

MAC Medium Access Control

MBMS Multimedia Broadcast Multicast Service

MBS Multicast-Broadcast Service

MBSFN Multicast Broadcast Single Frequency Network

MCCH Multicast Control Channel

MCE Multi-cell/multicast Coordination Entity

MCG Master Cell Group

MCH Multicast Channel

MIMO Multi-input Multi-output

MRB Multicast-Broadcast Service Radio Bearer

MR-DC Multi-RAT Dual Connectivity

MSG Message

MTCH Multicast Traffic Channel

NB-IoT Narrow Band Internet of Things

NDI New Data Indicator

NR New RAT/Radio

NUL Normal Uplink

NW Network

PCell Primary Cell

PDCCH Physical Downlink Control Channel

PDCP Packet Data Convergence Protocol

PDSCH Physical Downlink Shared Channel

PDU Protocol Data Unit

PHY Physical Layer

PMCH Physical Multicast Channel

PSCell Primary SCell

PTAG Primary Timing Advance Group

PTM Point to Multipoint

PTP Point to Point

PUCCH Physical Uplink Control Channel

PUSCH Physical Uplink Shared Channel

RA Random Access

RLC Radio Link Control

RNTI Radio Network Temporary Identifier

RRC Radio Resource Control

SCell Secondary Cell

SCG Secondary Cell Group

SC-MCCH Single Cell Multicast Control Channel

SC-MTCH Single Cell Multicast Traffic Channel

SC-N-RNTI Single Cell Notification Radio Network Temporary Identifier

SC-PTM Single Cell Point to Multipoint

SC-MRB Single Cell Multicast-Broadcast Service Radio Bearer

SC-RNTI Single Cell Radio Network Temporary Identifier

SDAP Service Data Adaptation Protocol

SDU Service Data Unit

SI System Information

SIB System Information Block

SR Scheduling Request

SRB Signaling Radio Bearer

SSB Synchronization Signal Block

SpCell Special Cell

SPS Semi Persistent Scheduling

SUL Supplementary Uplink

TA Timing Advance

TAG Timing Advance Group

TB Transport Block

TMGI Temporary Mobile Group Identity

TR Technical Report

TRP Transmission/Reception Point

TS Technical Specification

UE User Equipment

UL Uplink

UL-SCH Uplink Shared Channel

UM Unacknowledged Mode

WI Work Item

5GS 5G System

The following contains specific information related to implementations of the present disclosure. The drawings and their accompanying detailed disclosure are merely directed to implementations. However, the present disclosure is not limited to these implementations. Other variations and implementations of the present disclosure will be obvious to those skilled in the art. Unless noted otherwise, like or corresponding elements among the drawings may be indicated by like or corresponding reference numerals. Moreover, the drawings and illustrations in the present disclosure are generally not to scale and are not intended to correspond to actual relative dimensions.

For the purposes of consistency and ease of understanding, like features may be identified (although, in some examples, not illustrated) by the same numerals in the drawings. However, the features in different implementations may be different in other respects and shall not be narrowly confined to what is illustrated in the drawings.

The phrases “in one implementation, ” or “in some implementations, ” may each refer to one or more of the same or different implementations. The term “coupled” is defined as connected whether directly or indirectly via intervening components and is not necessarily limited to physical connections. The term “comprising” means “including, but not necessarily limited to” and specifically indicates open-ended inclusion or membership in the so-disclosed combination, group, series or equivalent. The expression “at least one of A, B and C” or “at least one of the following: A, B and C” means “only A, or only B, or only C, or any combination of A, B and C. ”

For the purposes of explanation and non-limitation, specific details such as functional entities, techniques, protocols, and standards are set forth for providing an understanding of the disclosed technology. In other examples, detailed disclosure of well-known methods, technologies, systems, and architectures are omitted so as not to obscure the present disclosure with unnecessary details.

Persons skilled in the art will immediately recognize that any network function (s) or algorithm (s) disclosed may be implemented by hardware, software or a combination of software and hardware. Disclosed functions may correspond to modules which may be software, hardware, firmware, or any combination thereof. A software implementation may include computer executable instructions stored on a computer readable medium such as memory or other type of storage devices. One or more microprocessors or general-purpose computers with communication processing capability may be programmed with corresponding executable instructions and perform the disclosed network function (s) or algorithm (s) . The microprocessors or general-purpose computers may include Application Specific Integrated Circuitry (ASIC) , programmable logic arrays, and/or using one or more Digital Signal Processor (DSPs) . Although some of the disclosed implementations are oriented to software installed and executing on computer hardware, alternative implementations implemented as firmware or as hardware or as a combination of hardware and software are well within the scope of the present disclosure.

The computer-readable medium includes but is not limited to Random Access Memory (RAM) , Read Only Memory (ROM) , Erasable Programmable Read-Only Memory (EPROM) , Electrically Erasable Programmable Read-Only Memory (EEPROM) , flash memory, Compact Disc Read-Only Memory (CD-ROM) , magnetic cassettes, magnetic tape, magnetic disk storage, or any other equivalent medium capable of storing computer-readable instructions.

A radio communication network architecture such as a Long-Term Evolution (LTE) system, an LTE-Advanced (LTE-A) system, an LTE-Advanced Pro system, or a 5G NR Radio Access Network (RAN) typically includes at least one base station (BS) , at least one UE, and one or more optional network elements that provide connection within a network. The UE communicates with the network such as a Core Network (CN) , an Evolved Packet Core (EPC) network, an Evolved Universal Terrestrial RAN (E-UTRAN) , a 5G Core (5GC) , or an internet via a RAN established by one or more BSs.

A UE may include but is not limited to a mobile station, a mobile terminal or device, or a user communication radio terminal. The UE may be a portable radio equipment that includes but is not limited to a mobile phone, a tablet, a wearable device, a sensor, a vehicle, or a Personal Digital Assistant (PDA) with wireless communication capability. The UE is configured to receive and transmit signals over an air interface to one or more cells in a RAN.

The BS may include but is not limited to a node B (NB) in the UMTS, an evolved node B (eNB) in LTE or LTE-A, a radio network controller (RNC) in UMTS, a BS controller (BSC) in the GSM/GERAN, an ng-eNB in an Evolved Universal Terrestrial Radio Access (E-UTRA) BS in connection with 5GC, a next generation Node B (gNB) in the 5G-RAN, or any other apparatus capable of controlling radio communication and managing radio resources within a cell. The BS may serve one or more UEs via a radio interface.

A BS may be configured to provide communication services according to at least a Radio Access Technology (RAT) such as Worldwide Interoperability for Microwave Access (WiMAX) , Global System for Mobile communications (GSM) that is often referred to as 2G, GSM Enhanced Data rates for GSM Evolution (EDGE) RAN (GERAN) , General Packet Radio Service (GPRS) , Universal Mobile Telecommunication System (UMTS) that is often referred to as 3G based on basic wideband-code division multiple access (W-CDMA) , high-speed packet access (HSPA) , LTE, LTE-A, evolved LTE (eLTE) that is LTE connected to 5GC, NR (often referred to as 5G) , and/or LTE-A Pro. However, the scope of the present disclosure is not limited to these protocols.

The BS is operable to provide radio coverage to a specific geographical area using a plurality of cells forming the RAN. The BS supports the operations of the cells. Each cell is operable to provide services to at least one UE within its radio coverage. Each cell (often referred to as a serving cell) may provide services to serve one or more UEs within its radio coverage such that each cell schedules the DL and optionally UL resources to at least one UE within its radio coverage for DL and optionally UL packet transmissions. The BS can communicate with one or more UEs in the radio communication system via the plurality of cells. A cell may allocate sidelink (SL) resources for supporting Proximity Service (ProSe) or Vehicle to Everything (V2X) service. Each cell may have overlapped coverage areas with other cells.

As discussed above, the frame structure for NR supports flexible configurations for accommodating various next generation (e.g., 5G) communication requirements such as Enhanced Mobile Broadband (eMBB) , Massive Machine Type Communication (mMTC) , and Ultra-Reliable and Low-Latency Communication (URLLC) , while fulfilling high reliability, high data rate and low latency requirements. The Orthogonal Frequency-Division Multiplexing (OFDM) technology in the 3rd Generation Partnership Project (3GPP) may serve as a baseline for an NR waveform. The scalable OFDM numerology such as adaptive sub-carrier spacing, channel bandwidth, and Cyclic Prefix (CP) may also be used. Additionally, two coding schemes are considered for NR, specifically Low-Density Parity-Check (LDPC) code and Polar Code. The coding scheme adaption may be configured based on channel conditions and/or service applications.

Moreover, it is also considered that in a transmission time interval TX of a single NR frame, at least downlink (DL) transmission data, a guard period, and uplink (UL) transmission data should be included, where the respective portions of the DL transmission data, the guard period, and the UL transmission data should also be configurable, for example, based on the network dynamics of NR. In addition, sidelink resources may also be provided in an NR frame to support ProSe services.

In addition, the terms “system” and “network” herein may be used interchangeably. The term “and/or” herein is only an association relationship for describing associated objects and represents that these relationships may exist. For example, A and/or B may indicate that: A exists alone, A and B exist at the same time, or B exists alone. In addition, the character “/” herein generally represents that the former and latter associated objects are in an “or” relationship.

Examples of some selected terms are provided as follows.

User Equipment (UE) : The UE may be referred to PHY/MAC/RLC/PDCP/SDAP/RRC entity. The PHY/MAC/RLC/PDCP/SDAP/RRC entity may be referred to the UE.

Network (NW) : The NW may be a network node, a TRP, a cell (e.g., SpCell, PCell, PSCell, and/or SCell) , an eNB, a gNB, and/or a base station.

Serving Cell: A PCell, a PSCell, or an SCell. The serving cell may be an activated or a deactivated serving cell.

Special Cell (SpCell) : For Dual Connectivity operation, the Special Cell may refer to the PCell of the MCG or the PSCell of the SCG depending on if the MAC entity is associated to the MCG or the SCG, respectively. Otherwise, the Special Cell may refer to the PCell. A Special Cell may support PUCCH transmission and contention-based Random Access, and may be always activated.

Component Carrier (CC) : The CC may be PCell, PSCell, and/or SCell.

Broadcast/multicast HARQ process: A HARQ process that is allocated to DL resources that may be specifically used for transmission of MBSs. The MBS HARQ process may be used for identifying a DL resource (for transmitting a TB/MAC PDU) . The DL resource may map to an MBS DL Transport channel (e.g., BCH, MCH) and/or MBS DL LCH (e.g., MTCH, MCCH, BCCH, SC-MTCH, SC-MCCH) .

Soft buffer: one soft buffer may correspond to a DL (MBS) HARQ process.

The UL grant may be used to indicate a PUSCH resource. The PUSCH resource may also be referred to as UL-SCH resource. In the case of Dual Connectivity (DC) or Multi-RAT Dual Connectivity (MR-DC) , an MBS may be supported by both the Master Node and the Secondary Node. The configuration related to the MBS may be delivered through SRB1 or SRB3. A TB may also be referred to as a MAC PDU. The configurations in the UL BWP (e.g., configuration of UL resource for transmission of control or data traffic) may be applied to both NUL and SUL. A NR MBS radio bearer may be used to receive MBS (s) in NR, and a UE may need to establish a NR MBS radio bearer for the reception of (DL) MBS (s) . One NR MBS radio bearer may be mapped to one or more LCHs. One NR MBS radio bearer may be used for reception of one or more MBSs. An MBS may be identified via TMGI or sessionId of the MBS. A PDCCH/search space may also be referred to as a CORESET.

In a multi-RAT connectivity scenario, the UE may receive the MBS configuration by reading the broadcast system information directly. In this scenario, the secondary node may be either eNB or gNB. The MBS configuration may be referred to both the MBMS configuration in LTE E-UTRA and/or MBS configuration in 5G NR. For example, the configurations that may be provided by the network via broadcast system information may be referred to as MBS configuration. For MBS configuration that is configured via dedicated RRC signaling, the master node may forward the MBS configuration generated by the secondary node. The secondary node may forward the MBS configuration generated by the master node. The MBS configuration may be referred to both the MBMS configuration in LTE E-UTRA and/or MBS configuration in 5G NR.

An LTE MBMS aims to provide an efficient mode of delivery both broadcast and multicast services over the core network. The broadcast service may be provided via a DL-only point-to-multipoint transmission from the network to multiple UEs, the content of the broadcast service may be transmitted once to all UEs in a geographical area, and users may be free to choose whether or not to receive the content of the broadcast service. The multicast service may be provided via a DL-only point-to-multipoint transmission from the network to a managed group of UEs, the content of the multicast service may be transmitted once to the whole group, and only the users belonging to the managed group can receive the content of the multicast service. According to the 3GPP Technical Specification (TS) 36.300 V16.3.0, a UE may receive MBMS (from the network) in RRC_IDLE state. A UE may receive MBMS (from the network) in RRC_CONNECTED state (if the UE is not a NB-IoT UE, BL UE or UE in enhanced coverage) . Transmission of a MBMS in E-UTRAN may use either MBSFN transmission or SC-PTM transmission. The MCE may make the decision on whether to use SC-PTM or MBSFN for each MBMS session.

The LTE MBMS may be transmitted using a SC-PTM transmission. The MBMS transmitted using the SC-PTM transmission may have the following characteristics (a) - (g) :

(a) The MBMS may be transmitted in the coverage of a single cell.

(b) One SC-MCCH and one or more SC-MTCHs may be mapped on a DL-SCH. The DL- SCH may be mapped to a PDSCH. The SC-MCCH and the SC-MTCH may be logical channels. The SC-MCCH may be a point-to-multipoint downlink channel used for transmitting MBMS control information (e.g., SCPTMConfiguration message as specified in the 3GPP TS 36.331 V16.2.0) from the network to the UE, for one or more SC-MTCHs. The SC-MCCH may be only used by UEs that receive or are interested to receive MBMS using SC-PTM. The SC-MTCH is a point-to-multipoint downlink channel used for transmitting traffic data from the network to the UE using SC-PTM transmission. The SC-MTCH may be only used by UEs that receive MBMS using SC-PTM.

(c) The SC-MCCH and/or the SC-MTCH may be mapped on SC-MRB. The SC-MRB may be a radio bearer used for reception of MBMS service (transmitted using SC-PTM transmission) .

(d) Scheduling may be done by the eNB.

(e) The SC-MCCH and the SC-MTCH transmissions (e.g., the PDSCH used for transmission of SC-MCCH information and the PDSCH used for transmission of SC-MTCH information) are each scheduled/indicated by a logical channel specific RNTI on PDCCH (there is a one-to-one mapping between TMGI and G-RNTI used for the reception of the DL-SCH to which a SC-MTCH is mapped) .

The PDCCH (DCI) associated (e.g., CRC scrambled) with a SC-RNTI may be used to indicate the transmission of the SC-MCCH (e.g., the PDSCH on which the SC-MCCH is mapped) .

The PDCCH (DCI) associated (e.g., CRC scrambled) with a G-RNTI may be used to indicate the transmission of the SC-MTCH (e.g., the PDSCH on which the SC-MTCH is mapped) .

The value of the SC-RNTI may be “FFFB” which is a value represented in hexadecimal, as specified in the 3GPP TS 36.321 V16.2.0.

The value of the G-RNTI and a (1-to-1) mapping between the G-RNTI and its respective TMGI/MBMS session is indicated via the SCPTMConfiguration message (e.g., SC-MCCH) . A single SCPTMConfiguration message may indicate a list of one or more G-RNTIs and their respective TMGIs/MBMS sessions.

(f) A single transmission may be used for the DL-SCH (i.e., neither blind HARQ repetitions nor RLC quick repeat) on which the SC-MCCH or the SC-MTCH is mapped.

(g) The SC-MCCH and the SC-MTCH may use the RLC-UM.

The MBS may be delivered via at least one of a unicast transmission and a multicast transmission. The broadcast/multicast service may be delivered from a single data source (e.g., the MBS server) to multiple UEs. Multiple delivery methods may be used to deliver the MBS traffic in the 5GS. FIG. 1 is a schematic diagram illustrating various delivery methods for delivering MBS traffic in the 5GS according to an example implementation of the present disclosure. From the 5G CN 100 point of view, the following two delivery methods (a) and (b) may be applied to the MBS.

(a) The 5GC individual MBS traffic delivery method. The 5G CN 100 may receive a single copy of MBS data packets 101 and may deliver separate copies of those MBS data packets 101 to individual UEs via per-UE PDU sessions. For example, the 5G CN 100 may receive a single copy of MBS data packets 101 and may deliver separate copies of those MBS data packets 101 to the UE 102 and UE 104 via the PDU session 103 and the PDU session 105, respectively. Hence, for each UE, one PDU session may be required to be associated with an MBS session. The 5GC individual MBS traffic delivery method may be referred to as a unicast delivery method.

(b) The 5GC shared MBS traffic delivery method. The 5G CN 100 may receive a single copy of MBS data packets 101 and may deliver a single copy of those MBS data packets 101 to a gNB (in the RAN 106) via the MBS session 107. then the gNB (in the RAN 106) may deliver the single copy of those MBS data packets to one or

more UEs

108, 110.

From the RAN 106 point of view (in the case of the 5GC shared MBS traffic delivery method) , the following two delivery methods (a) and (b) may be used for transmission of the MBS packet flows over the radio (e.g., between the gNB (in the RAN 106) and the UEs 108, 110) .

(a) The PTP delivery method. The gNB (in the RAN 106) may deliver separate copies of the MBS data packets over the radio to individual UE (e.g., the UE 108, 110) .

(b) The PTM delivery method. A gNB (in the RAN 106) may deliver a single copy of the MBS data packets over the radio to a set of UEs (e.g., the UEs 108, 110) . The PTP or PTM delivery method (with the 5GC shared delivery method) and the 5GC individual MBS traffic delivery method may be used at the same time for an MBS session.

For the 5GC individual MBS traffic delivery method, the transmission of an MBS session over the radio may be performed on a PDCCH for a C-RNTI and a DL-SCH MAC PDU may be received. For the PTP delivery method, DCI associated with C-RNTI may be transmitted on the PDCCH for scheduling of the MBS data packet in the DL. The PTP delivery method may be referred to as the unicast transmission or the PTP transmission in the present disclosure. For the PTM delivery method, a DCI associated with G-RNTI may be transmitted on PDCCH for scheduling of a group-common PDSCH in the DL. The group-common PDSCH (scrambled by the G-RNTI) may include MBS data packet. This transmission scheme may be referred to as PTM transmission scheme 1. In some implementations, for the PTM delivery method, a DCI associated with C-RNTI may be transmitted on PDCCH for scheduling of a group-common PDSCH in the DL. The group-common PDSCH (scrambled by the G-RNTI) may include MBS data packet. This transmission scheme may be referred to as PTM transmission scheme 2. In general, the PTM delivery method may be referred to as the multicast transmission or the PTM transmission in the present disclosure. Here, the G-RNTI may be associated with one or more MBSs. Each MBS may be associated with an MBS ID (e.g., TMGI, sessionId, G-RNTI, etc. ) . In some implementations, the network may transmit a message that includes a list of one or more G-RNTIs and their respective MBS (e.g., TMGI, sessionId, etc. ) to one or more UEs. Hence, a UE may maintain multiple G-RNTIs, and multiple UEs may share the same G-RNTI.

In 3GPP, it has been agreed to specify support for dynamic change of MBS delivery between the multicast transmission (e.g., the PTM transmission) and the unicast transmission (e.g., the PTP transmission) with service continuity for a UE. The network may dynamically change the MBS provisioning to a UE between the multicast transmission (e.g., the PTM transmission) and the unicast transmission (e.g., the PTP transmission) . Moreover, it is agreed that the network makes the decision of the dynamic switch. Whenever the network makes the decision of dynamic switch from the unicast transmission (e.g., the PTP transmission) to the multicast transmission (e.g., the PTM transmission) and/or from the multicast transmission (e.g., the PTM transmission) to the unicast transmission (e.g., the PTP transmission) for one or more MBSs, a switching indication (or different types of switching indications) may be transmitted to the UE (s) that is receiving the one or more MBSs.

One 5G protocol layer (e.g., the PDCP layer) may act as an anchor layer to support dynamic switch between the unicast transmission (e.g., the PTP transmission) and the multicast transmission (e.g., the PTM transmission) . FIG. 2 is a schematic diagram illustrating that the PDCP entity 201 of the BS/UE as an anchor to support dynamic switch according to an example implementation of the present disclosure. The DCI associated with the G-RNTI/C-RNTI 202 may be used for scheduling of group-common PDSCH including MBS data packet for the PTM delivery method. The DCI associated with the C-RNTI 204 may be used for scheduling dedicated (e.g., UE-specific) PDSCH including MBS data packet for the PTP delivery method.

In the present disclosure, an MRB may associate with a PDCP entity. The PDCP entity that associates with the MRB may associate with either one or two RLC entities. Each RLC entity may operate in either a RLC Unacknowledged Mode (RLC-UM) or a RLC Acknowledged Mode (RLC-AM) . In some implementations, the PDCP entity may associate with one RLC-UM entity for PTP transmission. In some implementations, the PDCP entity may associate with one RLC-AM entity for PTP transmission. In one case, the PDCP entity may associate with one RLC-UM entity for PTM transmission. In some implementations, the PDCP entity may associate with two RLC-UM entities, one for PTP transmission and the other for PTM transmission. In some implementations, the PDCP entity may associate with one RLC-UM entity for PTM transmission and one RLC-AM entity for PTP transmission. Taking FIG. 2 as an example, the PDCP entity 201 may associate with one RLC entity 203 for PTM transmission and one RLC entity 205 for PTP transmission. Here, the RLC entity 205 for PTP transmission may either operate in RLC-AM or RLC-UM, and the RLC entity 203 for PTM transmission may operate in RLC-UM. Moreover, in FIG. 2, the RLC entity 203 for PTM transmission and the RLC entity 205 for PTP transmission may both associate with the MAC entity 206.

An MRB may be referred to as a multicast MRB or a broadcast MRB. An MBS session may be referred to as a multicast session or a broadcast session. A multicast session may use a multicast mode, and a broadcast session may use a broadcast mode. A multicast MRB may be used for a multicast session, and a broadcast MRB may be used for a broadcast session. The PTM transmission scheme may be used/configured for a broadcast MRB. At least one of PTP transmission scheme and PTM transmission scheme may be used/configured for a multicast MRB. The dynamic switching may refer to activation/deactivation of PDCCH monitoring for DCI associated with G-RNTI.

In the present disclosure, the detailed design of the switching indication is described, e.g., how the switching indication (s) is provided from the network to the UE. The UE behaviors upon/after receiving the switching indication, from the network, are also described in the present disclosure. FIG. 3 is a dynamic switch procedure 300 of MBS delivery according to an example implementation of the present disclosure. In action 302, the network 320 may deliver an MBS (or data of an MBS) via the PTP transmission to the UE 310. While the network 320 delivers the MBS via PTP transmission, the UE 310 may monitor on PDCCH for DCI associated with C-RNTI that schedules dedicated (e.g., UE-specific) PDSCH. In action 304, the network 320 may transmit a switching indication to the UE 310. The switching indication may indicate that a transmission mode of the MBS is switched from the PTP transmission to the PTM transmission. In action 306, the UE 310 may transmit a confirmation (e.g., a confirmation message) to the network 320 in response to reception of the switching indication from the network 320. In action 308, the network 320 may deliver the MBS (or the data of the MBS) via the PTM transmission to the UE 310. While the network 320 delivers the MBS via PTM transmission, the UE 310 may monitor on PDCCH for DCI associated with C-RNTI/G-RNTI that schedules group-common PDSCH.

The switching indication may be a (common or dedicated) RRC message, a (common or dedicated) PDCP control PDU, a (common or dedicated) RLC control PDU, a (common or dedicated) MAC CE, and/or a (common or dedicated) L1 signaling (e.g., DCI) . These kinds of switching indication may be broadcasting, multicasting, or unicasting. In other words, the switching indication (s) may be provided via common, group-common, or dedicated signaling.

The switching indication may identify one or more MBSs in which the transmission mode needs to be switched, e.g., from the multicast transmission to the unicast transmission or from the unicast transmission to the multicast transmission. The switching indication may include the identity of the one or more MBSs in which the transmission mode needs to be switched, e.g., from the multicast transmission to the unicast transmission or from the unicast transmission to the multicast transmission. The switching indication may indicate the identity of one or more MBSs in which the transmission mode needs to be switched (e.g., by indicating the TMGI, sessionId, LCID, bearer ID, QoS flow ID, etc., that corresponds to the one or more MBSs) . Upon/After receiving the switching indication, the UE may determine the one or more MBSs in which the transmission mode (s) need to be switched and may perform the action described in the present disclosure.

In some implementations, there may be two different switching indications, one for indicating the transmission mode of an MBS/MBSs is/are commanded to switch from the PTP transmission to the PTM transmission, the other for indicating the transmission mode of an MBS(s) /MBSs is/are commanded to switch from the PTM transmission to the PTP transmission. In some implementations, there may be only one switching indication for indicating the transmission mode of an MBS/MBSs is/are commanded to switch from the PTP transmission to the PTM transmission. There may be no switching indication for indicating the transmission mode of an MBS/MBSs is/are commanded to switch from the PTM transmission to the PTP transmission. If a UE receives the switching indication for indicating the transmission mode of an MBS/MBSs is/are commanded to switch from the PTP transmission to the PTM transmission, the corresponding configuration for PTP reception associated the indicated MBS/MBSs may be released or suspended. In some implementations, there may be only one switching indication for indicating the transmission mode of an MBS/MBSs is/are commanded to switch from the PTM transmission to the PTP transmission. There may be no switching indication for indicating the transmission mode of an MBS/MBSs is/are commanded to switch from the PTP transmission to the PTM transmission. If a UE receives the switching indication for indicating the transmission mode of an MBS/MBSs is/are commanded to switch from the PTM transmission to the PTP transmission, the corresponding configuration for PTM reception associated the indicated MBS (s) may be released or suspended.

The DCI used for the MBS related scheduling may have one field to identify one or more MBSs in which the transmission mode needs to be switched. For example, the field may provide a bit map for indicating the corresponding MBS whether to change the transmission mode. If the bit is “0” , the transmission mode may not be changed. If the bit is “1” , the transmission mode may be changed, e.g., the transmission mode is changed from the multicast transmission to the unicast transmission or from the unicast transmission to the multicast transmission.

The switching indication may include the identity of a group of one or more MBSs in which the transmission mode needs to be switched, e.g., from the multicast transmission to the unicast transmission or from the unicast transmission to the multicast transmission. In some implementations, the network may configure, to a UE, one or more MBSs in a group (e.g., by providing the one or more MBSs with the same group ID) . Then, the network may transmit the switching indication to the UE. The switching indication may identify the group in which the transmission mode needs to be switched. This may be done by including a group ID of the group in the switching indication. Upon/After receiving the switching indication, the UE may determine the group of one or more MBSs in which the transmission mode needs to be switched and may perform the action described in the present disclosure.

In some implementations, there may be two different switching indications, one for indicating the transmission mode of an MBS/MBSs is/are switched from the PTP transmission to the PTM transmission, the other for indicating the transmission mode of an MBS/MBSs is/are switched from the PTM transmission to the PTP transmission. The network may send one of the two switching indications together with a group ID. In some implementations, there may be only one switching indication for indicating the transmission mode of an MBS/MBSs is/are commanded to switch from the PTP transmission to the PTM transmission. There may be no switching indication for indicating the transmission mode of an MBS/MBSs is/are commanded to switch from the PTM transmission to the PTP transmission. The network may send the switching indication together with a group ID. In some implementations, there may be only one switching indication for indicating the transmission mode of an MBS/MBSs is/are commanded to switch from the PTM transmission to the PTP transmission. There may be no switching indication for indicating the transmission mode of an MBS/MBSs is/are commanded to switch from the PTP transmission to the PTM transmission. The network may send the switching indication together with a group ID.

Table 1 shows an example of a mapping between MBS group ID and MBS IDs. The network may configure/provide the mapping between MBS group ID and MBS IDs (e.g., G-RNTI, TMGI, sessionId, LCID, bearer ID, QoS flow ID, etc. ) to MBS interested UEs, e.g., the network may provide the information such as Table 1 to one or more UEs via broadcast system information (e.g., SIB) or dedicated RRC signaling. After the network provides such information, the UE may consider MBSs with the same MBS group ID as the same MBS group. The DCI used for MBS related scheduling may have one field to identify a group of one or more MBSs (e.g., one or more MBS IDs) in which the transmission mode needs to be switched. For example, the field may provide a bit map for indicating the corresponding MBS group whether to change the transmission mode. If a first value (e.g., “0” ) is used in a bit, the transmission mode may not be changed for the MBS group that corresponds to the bit. If a second value (e.g., “1” ) is used in the bit, the transmission mode may be changed for the MBS group that corresponds to the value the bit, e.g., the transmission mode is changed from the multicast transmission to the unicast transmission or from the unicast transmission to the multicast transmission.

Table 1

MBS Group ID	MBS ID
0	3
1	0, 1, 5
2	2, 4
3	6, 7

The mapping between CORESET/PDCCH/search space and one or more MBSs and/or one or more MBS service groups may be provided, by the network, via broadcast system information (e.g., SIB) or dedicated signaling (e.g., RRC signaling) . The network may indicate that a CORESET/PDCCH/search space (e.g., CORESET/PDCCH/search space with a specific ID) may be used to receive scheduling of one or more MBSs and/or one or more MBS groups. The network may indicate whether the UE can receive scheduling of new transmission and/or scheduling of retransmission for (each of) the one or more MBSs and/or (each of) the one or more MBS groups on the CORESET/PDCCH/search space (e.g., CORESET/PDCCH/search space with the specific ID) . The network may indicate whether the UE can receive scheduling of the PTP transmission (e.g., the DCI associated with the C-RNTI) or the PTM transmission (e.g., the DCI associated with the C-RNTI and/or the G-RNTI) for (each of) the one or more MBSs and/or (each of) the one or more MBS groups on the CORESET/PDCCH/search space (e.g., CORESET/PDCCH/search space with the specific ID) .

A CORESET/PDCCH/search space used for the PTM transmission (of an MBS) may be different from a CORESET/PDCCH/search space used for the PTP transmission (of the same MBS) . The CORESET/PDCCH/search space used for the PTM transmission and/or the PTP transmission (of an MBS) may be provided by the network via broadcast system information (e.g., SIB) or dedicated signaling (e.g., RRC signaling) . In some implementations, the CORESET/PDCCH/search space used for the PTM transmission and/or the PTP transmission may be preconfigured in the UE. The search space used for the PTM transmission (of an MBS) may be at least a common search space and a UE-specific search space. The search space used for the PTP transmission (of an MBS) may be a UE-specific search space. In some implementations, the network may independently configure a CORESET/PDCCH/search space configuration used for the PTM transmission (of an MBS) and independently configure a CORESET/PDCCH/search space configuration used for the PTP transmission (of the same MBS) . In other words, a CORESET/PDCCH/search space configuration used for the PTM transmission (of an MBS) may be independent from a CORESET/PDCCH/search space configuration used for the PTP transmission (of the same MBS) . The CORESET/PDCCH/search space configuration of an MBS may (only) be configured in the same Cell/BWP/MBS common frequency resource where the MBS is configured.

A CORESET/PDCCH/search space used for monitoring DCI associated with a G-RNTI (for scheduling of MBS data) may be different from a CORESET/PDCCH/search space used for monitoring DCI associated with a C-RNTI (for scheduling of MBS data) . The CORESET/PDCCH/search space used for monitoring DCI associated with G-RNTI and/or C-RNTI (for scheduling of MBS data) may be provided by the network via broadcast system information (e.g., SIB) or dedicated signaling (e.g., RRC signaling) . In some implementations, the CORESET/PDCCH/search space used for monitoring DCI associated with G-RNTI and/or C-RNTI (for scheduling of MBS data) may be preconfigured in the UE. In some implementations, the network may independently configure a CORESET/PDCCH/search space configuration used for monitoring DCI associated with a G-RNTI and independently configure a CORESET/PDCCH/search space configuration used for monitoring DCI associated with a C-RNTI. In other words, a CORESET/PDCCH/search space configuration used for monitoring DCI associated with a G-RNTI may be independent from a CORESET/PDCCH/search space configuration used for monitoring DCI associated with a C-RNTI. Here, the DCI associated with a C-RNTI may be a DL assignment that is used to schedule a group-common PDSCH (including MBS data) or a UE-specific PDSCH (including unicast data) .

A CORESET/PDCCH/search space used for monitoring DCI associated with a first G-RNTI (for scheduling data of a first MBS) may be different from a CORESET/PDCCH/search space used for monitoring DCI associated with a second G-RNTI (for scheduling data of a second MBS) . In some implementations, the network may independently configure a CORESET/PDCCH/search space configuration used for monitoring DCI associated with a first G-RNTI (for scheduling data of a first MBS) and independently configure a CORESET/PDCCH/search space configuration used for monitoring DCI associated with a second G-RNTI (for scheduling data of a second MBS) .

The switching indication may include the identity of the CORESET/PDCCH/search space in which the transmission mode needs to be switched. The network may configure, to a UE, one or more MBSs to a specific CORESET/PDCCH/search space (e.g., by providing the one or more MBSs the same SearchSpaceId/ControlResourceSetId) . The UE may monitor the DL scheduling information that schedules the one or more MBSs via the specific CORESET/PDCCH/search space. Then, the network may transmit a switching indication to the UE. The switching indication may identify the specific CORESET/PDCCH/search space in which the transmission mode needs to be switched. This may be done by including a SearchSpaceId/ControlResourceSetId of the specific CORESET/PDCCH/search space in the switching indication. Upon/After receiving the switching indication, the UE may determine the one or more MBSs corresponding to the specific CORESET/PDCCH/search space in which the transmission mode needs to be switched and may stop monitor the specific CORESET/PDCCH/search space. The switching indication may also include the new CORESET/PDCCH/search space. Upon/After reception of the switching indication, the UE may begin to monitor the new CORESET/PDCCH/search space included in the switching indication.

The network may configure, to a UE, which CORESET/PDCCH/search space are used for transmission mode switching. If the UE monitors the MBS related DCI in the CORESET/PDCCH/search space configured for transmission mode switching, the transmission mode may be changed from the multicast transmission to the unicast transmission or from the unicast transmission to the multicast transmission. The UE may only receive the switching indication on a CORESET/PDCCH/search space that is for transmission mode switching.

The mapping between a Cell/BWP/MBS common frequency resource and one or more MBSs and/or one or more MBS groups may be provided, by the network, via broadcast system information (e.g., SIB) or dedicated signaling (e.g., RRC signaling) . The network may indicate that the Cell/BWP/MBS common frequency resource (e.g., Cell/BWP/MBS common frequency resource with a specific ID) may be used to receive (scheduling of) one or more MBSs and/or one or more MBS groups. The network may indicate whether the UE can receive (scheduling of) new transmission and/or (scheduling of) retransmission for (each of) the one or more MBSs and/or (each of) the one or more MBS groups on the BWP/common frequency resource (e.g., Cell/BWP/MBS common frequency resource with the specific ID) . The network may indicate whether the UE can receive (scheduling of) the PTP transmission or the PTM transmission for (each of) the one or more MBSs and/or (each of) the one or more MBS groups on the BWP/common frequency resource (e.g., Cell/BWP/MBS common frequency resource with the specific ID) .

The switching indication may include the identity of the Cell/BWP/MBS common frequency resource in which the transmission mode needs to be switched. The network may configure, to a UE, one or more MBSs to a specific Cell/BWP/MBS common frequency resource (e.g., by providing the one or more MBSs with the same bwp-Id) . The UE may monitor the one or more MBSs on the specific Cell/BWP/MBS common frequency resource. Then, the network may transmit the switching indication to the UE. The switching indication may identify the specific Cell/BWP/MBS common frequency resource in which the transmission mode needs to be switched. This may be done by including a bwp-Id of the specific Cell/BWP/MBS common frequency resource in the switching indication. Upon/After receiving the switching indication, the UE may determine the one or more MBSs corresponding to the specific Cell/BWP/MBS common frequency resource in which the transmission mode needs to be switched, and may perform the action described in the present disclosure. The switching indication may also include the new Cell/BWP/MBS common frequency resource. Upon/After reception of the switching indication, the UE may begin to monitor the Cell/BWP/MBS common frequency resource included in the switching indication.

The switching indication may explicitly indicate whether one or more (identified) MBSs needs to switch the transmission mode from the multicast transmission to the unicast transmission or from the unicast transmission to the multicast transmission. In some implementations, a first value (e.g., “1” ) may be used to indicate the transmission mode switching from the multicast transmission to the unicast transmission, and a second value (e.g., “0” ) may be used to indicate the transmission mode switching from the unicast transmission to the multicast transmission. The first value and the second value may be included in at least one of the following fields 1 to 6 of the switching indication.

Field 1: The switching indication may be a L1 signaling (e.g., a DCI) , which may be referred to as a switching indication L1 signaling. The field 1 may be a field in the switching indication L1 signaling. The field 1 may be an NDI field in the DCI field. The field 1 may be a HARQ ID field in the DCI field.

Field 2: The switching indication may be a MAC CE, which may be referred to as a switching indication MAC CE. The filed 2 may a field in MAC subheader that corresponds to the switching indication MAC CE. A first LCID value in (the LCID field of) the MAC subheader that corresponds to the switching indication MAC CE may indicate the transmission mode switching from the multicast transmission to the unicast transmission, and a second LCID value in (the LCID field of) the MAC subheader that correspond to the switching indication MAC CE may indicate the transmission mode switching from the unicast transmission to the multicast transmission.

Field 3: The switching indication may be a MAC CE, which may be referred to as a switching indication MAC CE. The filed 3 is a field in the switching indication MAC CE.

Field 4: The switching indication may a RLC control/data PDU. The field 4 may be a field in the RLC control/data PDU.

Field 5: The switching indication may be a PDCP control/data PDU. The filed 4 may be a field in the PDCP control/data PDU.

Field 6: The switching indication may be a RRC message. The filed 6 may be a field in RRC message.

In some implementations, the switching indication may be a bitmap that includes multiple bits. The bitmap may be included in at least one of the fields 1 to 6 as described above (e.g., from the field 1 to the field 6) . Each bit in the bitmap may correspond to at least one of an MBS and an MBS group. A first bit may correspond to a first MBS or a first MBS group, a second bit may correspond to a second MBS or a second MBS group, and so on. Table 2 shows an example of an MBS table. In the MBS table, each element may correspond to one or more the MBS IDs. Each bit in the bitmap may correspond to an element of the MBS table (e.g., Table 2) .

Table 2

Element	MBS ID
1	3
2	0, 1, 5
3	2, 4
4	6, 7

A first value (e.g., “1” ) in the first bit may indicate the transmission mode switching from the multicast transmission to the unicast transmission for the first MBS/the first MBS group/the first element of the MBS table, and a second value (e.g., “0” ) in the first bit may indicate the transmission mode switching from the unicast transmission to the multicast transmission for the first MBS/the first MBS group) /the first element of the MBS table. A first value (e.g., “1” ) in the second bit may indicate the transmission mode switching from the multicast transmission to the unicast transmission for the second MBS/the second MBS group) /the second element of the MBS table, and a second value (e.g., “0”) in the second bit may indicate the transmission mode switching from unicast transmission to multicast transmission for the second MBS/the second MBS group/the second element of the MBS table. An MBS ID (e.g., G-RNTI, TMGI, sessionId, LCID, bearer ID, QoS flow ID, etc. ) may be mapped to each MBS. Such a mapping may be configured by the network or preconfigured in the UE. One or more MBSs may be mapped to an MBS group. Such a mapping may be configured by the network or preconfigured in the UE. The MBS table (e.g., Table 2) may be configured by the network via dedicated (RRC) signalling or broadcast system information (e.g., SIB) . Taking Table 2 for example, a first value (e.g., “1” ) in the first bit may indicate the transmission mode switching from the multicast transmission to the unicast transmission for the MBS with ID=3, and a second value (e.g., “0”) in the first bit may indicate the transmission mode switching from the unicast transmission to the multicast transmission for the MBS with ID=3.

The switching indication may include multiple bits. The multiple bits may be included in at least one of the fields 1 to 6 as described above (e.g., the multiple bits may be included in a DCI-based, MAC CE-based, RLC control/data PDU-based, PDCP control/data PDU-based, and/or RRC message-based switching indication) . On the other hand, the MBS table (e.g., Table 2) may include multiple elements. Each value in the multiple bits may correspond to an element of the MBS table (e.g., Table 2) . For example, a first value (e.g., value 0) in the multiple bits may correspond to a first element of the MBS table, a second value (e.g., value 1) in the multiple bits may correspond to a second element of the MBS table, and so on. The MBS table (e.g., Table 2) may be configured by the network via dedicated (RRC) signalling or broadcast system information (e.g., SIB) . An element of the MBS table (e.g., Table 2) may correspond to one or more MBSs and/or one or more MBS groups. Taking Table 2 for example, if the switching indication indicates a value of 2 (e.g., 01 in binary) , it may imply the transmission mode of the MBS with ID of 0, 1, and 5 may be switched.

The switching indication may only be transmitted on specific Cell/BWP/frequency resource. Specifically, the switching indication may only be transmitted on at least one of the following locations 1-4.

Location 1: A specific BWP. The specific BWP may be the UE’s default BWP/initial BWP. The specific BWP may be the UE’s dormant BWP. The specific BWP may be a BWP explicitly configured by the network (or preconfigured by the UE) to be explicitly used for the transmission of the MBSs, e.g., for the transmission of the data from an MBS radio bearer. The UE may use both the UE-specific RNTI (e.g., the C-RNTI) to decode the scheduling information of an MBS (e.g., the unicast transmission) and the G-RNTI to decode the scheduling information of an MBS (e.g., the multicast transmission) . The specific BWP may be a BWP for the transmission of the data from a unicast radio bearer (e.g., DRB) .

Location 2: An MBS common frequency resource. The MBS common frequency resource may be a frequency resource that is within the frequency range of a (dedicated) BWP configured for a UE.The MBS common frequency may be used for the transmission of the DL MBS data packet (e.g., the MBS radio bearer that is other than the DRB) via the unicast transmission and/or the multicast transmission The MBS common frequency resource may not be used for the transmission of the DL unicast data packet (e.g., the DRB) . The network may configure one MBS common frequency resource in a (dedicated) BWP configured for the UE.

Location 3: A specific cell. The specific cell may be the SpCell. The specific cell may be a cell explicitly configured by the network (or preconfigured by the UE) to be explicitly used for the transmission of the MBSs, e.g., for the transmission of the data from an MBS radio bearer. The UE may use both the UE-specific RNTI (e.g., the C-RNTI) to decode the scheduling information of an MBS (e.g., the unicast transmission) and the G-RNTI to decode the scheduling information of an MBS (e.g., the multicast transmission) .

Location 4: A specific CORESET/PDCCH/search space. The specific cell may be a cell explicitly configured by the network (or preconfigured by the UE) . The switching indication may be delivered in the group common PDCCH (if the serving cell instructs the UE to switch from the PTM transmission to the PTP transmission) . The switching indication may be delivered in the UE-specific PDCCH (if the serving cell instructs the UE to switch from the PTP transmission to the PTM transmission) .

A UE may not move to a dormant BWP, if the UE is still interested in receiving an MBS. A UE may not move to a dormant BWP, if the UE has established a LCH that is mapped to an NR MBS radio bearer. The network may map a LCH to a NR MBS radio bearer by including the ID of the LCH and the ID of the NR MBS radio bearer in the same RLC-BearerConfig.

In the following, the UE behavior upon (or after) receiving the switching indication is described. The UE may perform at least one of the following actions (a) - (c) upon/after receiving the switching indication from the network. The UE may perform at least one of the following actions (a) -(c) after a period upon/after receiving the switching indication from the network. The period may be preconfigured by the UE or configured by the network. The at least one of following actions (a) - (c) may be performed by the UE in an orderly fashion.

(a) Stop/start the PDCCH/search space monitoring for the UE’s group RNTI.

The UE’s group RNTI may be a G-RNTI or another type of RNTI that is common among multiple UEs. One or more UEs that receive on a (common) PDCCH/search space associated with the same group RNTI (e.g., the G-RNTI) may receive the same MBS (s) . The switching indication transmitted by the network may identify one or more MBSs that needs to switch the transmission mode, e.g., from the multicast transmission to the unicast transmission and/or from the unicast transmission to the multicast transmission. When the UE receives the switching indication identifying the one or more MBSs, the UE may stop/start the PDCCH/search space monitoring for the UE’s group RNTI that only corresponds to the identified MBSs. The mapping between the group RNTI and one or more MBSs may be provided by the network via broadcast system information (e.g., SIB) or dedicated signaling (e.g., RRC signaling) .

The UE may receive MBS 1 via UE’s group RNTI 1 and MBS 2 via UE’s group RNTI 2. The UE may receive both MBSs via the multicast transmission. Upon/After reception of the switching indication that identifies change in the transmission mode of the MBS 1 (e.g., from the multicast transmission to the unicast transmission) , the UE may only stop the PDCCH/search space monitoring for the UE’s group RNTI 1. The UE may (re) start the PDCCH/search space monitoring for receiving the MBS data via the PTP transmission (e.g., based on the PTP configuration (s) for MBS1) . The UE may continue the PDCCH/search space monitoring for the UE’s group RNTI 2. Upon/After reception of another switching indication that identifies change in transmission mode of MBS 1 (e.g., from the unicast transmission to the multicast transmission) , the UE may resume/ (re) start the PDCCH/search space monitoring for the UE’s group RNTI 1.

The UE may stop/start the PDCCH/search space monitoring for the UE’s group RNTI (that corresponds to an MBS) upon/after reception of the switching indication (that indicates transmission switching of the MBS) from the network. Upon/After reception of the switching indication (for the MBS) from the network, the UE may stop/start the PDCCH/search space monitoring for the UE’s group RNTI (that corresponds to the MBS) in the first symbol/slot/subframe after the end of the DL transmission carrying the switching indication. The UE may not continue monitoring the rest of the PDCCH/search space for the switching indication upon the switching indication is received successfully during the monitoring progress.

The UE may stop/start the PDCCH/search space monitoring for the UE’s group RNTI (that corresponds to an MBS) after a period T1 upon/after reception of the switching indication from the network. Upon/After reception of the switching indication (for the MBS) from the network, the UE may stop/start the PDCCH/search space monitoring for the UE’s group RNTI (that corresponds to the MBS) in the first symbol/slot/subframe after the period T1. The period T1 may be preconfigured in the UE and/or configured by the network via broadcast system information (e.g., SIB) or dedicated signaling (e.g., RRC signaling) . The period T1 may be in units of symbol, slot, subframe, millisecond, second, etc.

The UE may stop/start the PDCCH/search space monitoring for the UE’s group RNTI (that corresponds to an MBS) (after a period T1) upon/after transmitting a feedback in response to reception of the switching indication (for the MBS) from the network. The feedback may be a RRC message, a PDCP status report, a RLC status PDU, a confirmation MAC CE, a HARQ ACK/NACK, etc. The confirmation MAC CE/RRC message may indicate whether the switching indication has been received by the UE. The confirmation MAC CE/RRC message may indicate whether the switching indication corresponding to a specific service has been received by the UE. The confirmation MAC CE/RRC message may include a bitmap with i bits. Each bit in the bitmap may be mapped/corresponded to a specific MBS. Each bit in the bitmap may be mapped/corresponded to an element of an MBS table (e.g., Table 2) . A first value in a first bit may be used to indicate that the switching indication which is used for switching the transmission mode for the MBS corresponding to the first bit, has been received by the UE. A second value in a first bit may be used to indicate that the switching indication which is used for switching the transmission mode for the MBS corresponding to the first bit, has not been received by the UE. The first value in the first bit may be used to indicate that the switching indication which is used for switching the transmission mode for the MBS corresponding to the first element of the MBS table (e.g., Table) , has been received by the UE. The second value in the first bit may be used to indicate that the switching indication which is used for switching the transmission mode for the MBS corresponding to the first element of the MBS table (e.g., Table 2) , has not been received by the UE.

If the switching indication (for an MBS) is received by the UE, the UE may stop/start the PDCCH/search space monitoring for the UE’s group RNTI (that corresponds to the MBS) upon/after transmitting a feedback in response to reception of the switching indication (for the MBS) from the network. The feedback may be a HARQ feedback (e.g., HARQ ACK/NACK) corresponding to the HARQ process of the TB carrying the switching indication. The feedback may be a confirmation MAC CE, RLC status PDU, PDCP status report, and/or RRC confirmation message. The UE may stop/start the PDCCH/search space monitoring for the UE’s group RNTI after a period T1, upon/after transmitting the feedback in response to reception of the switching indication.

The UE may stop the PDCCH/search space monitoring for the UE’s group RNTI (that corresponds to an MBS) if the switching indication received from the network indicates switching (of the MBS) from the multicast transmission to the unicast transmission. The UE may start the PDCCH/search space monitoring for the UE’s group RNTI (that corresponds to an MBS) if the switching indication received from the network indicates switching (of the MBS) from the unicast transmission to the unicast transmission.

(b) Start/stop monitoring on a specific PDCCH/search space/Cell/BWP/MBS common frequency resource.

The specific PDCCH/search space/Cell/BWP/MBS common frequency resource may be used to monitor the UE’s C-RNTI, G-RNTI, UE-specific RNTI, etc. The UE-specific RNTI may correspond to one or more MBSs. The mapping between each UE-specific RNTI and one or more MBSs may be preconfigured in the UE and/or configured by the network via broadcast system information (e.g., SIB) or dedicated signaling (e.g., RRC signaling) .

In some implementations, the specific PDCCH/search space/Cell/BWP/MBS common frequency resource may correspond to one or more MBSs. The UE may only receive DL assignment (e.g., DCI associated with G-RNTI, UE-specific RNTI, and/or C-RNTI) which schedules the new transmission and/or retransmission of one or more MBSs, on the specific PDCCH/search space/Cell/BWP/MBS common frequency resource. The UE may only receive the MAC PDU (e.g., TB) which corresponds to the one or more services, on the specific Cell/BWP/MBS common frequency resource. The PDSCH for transmission of the MBS (from the network to the UE) may only be configured, by the network, on the specific Cell/BWP/MBS common frequency resource.

The switching indication transmitted by the network may identify one or more MBSs that needs to switch the transmission mode, i.e., from the multicast transmission to the unicast transmission and/or from the unicast transmission to the multicast transmission. In some implementations, when the UE receives the switching indication which indicates the transmission mode switching from the unicast transmission to the multicast transmission (for one or more MBSs) , the UE may stop monitoring on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via unicast transmission. The UE may receive the DCI associated with the C-RNTI and/or the UE-specific RNTI (that corresponds to the one or more MBSs) on specific PDCCH (s) /search space (s) . The specific PDCCH (s) /search space (s) may be used for receiving DCI indicating scheduling information (e.g., the DL assignment) of (the one or more) MBSs for new transmission and/or retransmission. Note that for a new transmission, the NDI indicated in the DCI for the DL assignment may be toggled when comparing with the previous DL assignment with the same HARQ process.

In some implementations, when the UE receives the switching indication which indicates the transmission mode switching from the unicast transmission to the multicast transmission (for one or more MBSs) , the UE may stop monitoring on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the unicast transmission. The UE may receive the DCI associated with the C-RNTI and/or the UE-specific RNTI (that corresponds to the one or more MBSs) on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the unicast transmission. The specific PDCCH (s) /search space (s) , which is for scheduling (the one or more) MBSs via the unicast transmission, may be used for scheduling new transmission and/or retransmission for (the one or more) MBSs. In the case of new transmission, the NDI received on the specific PDCCH may be toggled compared to the value in the previously received HARQ information for the HARQ Process ID. In the case of new transmission, the NDI received on the specific PDCCH may not be toggled compared to the value in the previously received HARQ information for the HARQ Process ID. The UE may stop its monitoring on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the unicast transmission, after a period T2 upon/after receiving the switching indication.

In some implementations, when the UE receives the switching indication which indicates the transmission mode switching from the unicast transmission to the multicast transmission (for one or more MBSs) , the UE may stop monitoring DCI associated with a specific RNTI, e.g., C-RNTI and/or UE-specific RNTI, on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the unicast transmission. When the UE receives the switching indication which indicates the transmission mode switching from the unicast transmission to the multicast transmission (for one or more MBSs) , the UE may stop monitoring on the specific PDCCH (s) /search space (s) that is for scheduling new transmission and/or retransmission of (the one or more) MBSs via the unicast transmission. When the UE receives the switching indication which indicates the transmission mode switching from the unicast transmission to the multicast transmission (for one or more MBSs) , the UE may start monitoring on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the multicast transmission.

The UE may receive DCI associated with the G-RNTI (that corresponds to the one or more MBSs) on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via multicast transmission. The specific PDCCH (s) /search space (s) which is for scheduling (the one or more) MBSs via the multicast transmission, may be used for scheduling new transmission and/or retransmission for (the one or more) MBSs. In the case of new transmission, the NDI received on the specific PDCCH may be toggled compared to the value in the previously received HARQ information for the HARQ Process ID. In the case of new transmission, the NDI received on the specific PDCCH may not be toggled compared to the value in the previously received HARQ information for the HARQ Process ID.

The UE may commence its monitoring on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the multicast transmission after a period T2, upon/after receiving the switching indication. The UE may commence its monitoring on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the multicast transmission after a period T2, upon/after the UE stops its monitoring on the other specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the unicast transmission.

The UE may perform BWP switching (after a period T2) , upon/after receiving the switching indication that indicates the transmission mode switching from the unicast transmission to the multicast transmission (for the one or more MBSs) . The UE may perform BWP switching (after a period T2) , upon/after receiving the switching indication that indicates the transmission mode switching from the unicast transmission to the multicast transmission (for the one or more MBSs) . The UE may perform BWP switching (after a period T2) , upon/after transmitting a feedback in response to reception of the switching indication (for the one or more MBSs) from the network. The feedback may be a RRC message, a PDCP status report, a RLC status PDU, a confirmation MAC CE, a HARQ ACK/NACK, etc. The confirmation MAC CE/RRC message may indicate whether the switching indication has been received by the UE. The confirmation MAC CE/RRC message may indicate whether the switching indication corresponding to a specific service has been received by the UE.

The network may configure, to a UE, specific PDCCH (s) /search space (s) that is for scheduling (one or more) MBSs via the unicast transmission on a first BWP, and configure the UE specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the multicast transmission on a second BWP. If the UE is initially receiving (the one or more) MBSs via the unicast transmission on the first BWP, the UE may perform BWP switching from the first BWP to the second BWP upon/after reception of the switching indication that indicates the transmission mode switching from the unicast transmission to the multicast transmission (for the one or more MBSs) . The switching indication may or may not include the identity of the new BWP (e.g., BWP ID) that the UE may switch to (e.g., the second BWP) .

When the UE receives the switching indication which indicates the transmission mode switching from the unicast transmission to the multicast transmission (for one or more MBSs) , the UE may start monitoring DCI associated with a specific RNTI, e.g., G-RNTI, on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the multicast transmission. When the UE receives the switching indication which indicates the transmission mode switching from the unicast transmission to the multicast transmission (for one or more MBSs) , the UE may start monitoring on the specific PDCCH (s) /search space (s) that is for scheduling new transmission and/or retransmission of (the one or more) MBSs via the multicast transmission. When the UE receives the switching indication which indicates the transmission mode switching from the multicast transmission to the unicast transmission (for one or more MBSs) , the UE may stop monitoring on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the multicast transmission. When the UE receives the switching indication which indicates the transmission mode switching from the multicast transmission to the unicast transmission (for one or more MBSs) , the UE may stop monitoring DCI associated with a specific RNTI, e.g., G-RNTI, on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the multicast transmission. When the UE receives the switching indication which indicates the transmission mode switching from the multicast transmission to the unicast transmission (for one or more MBSs) , the UE may stop monitoring on the specific PDCCH (s) /search space (s) that is for scheduling new transmission and/or retransmission of (the one or more) MBSs via the multicast transmission. When the UE receives the switching indication which indicates the transmission mode switching from the multicast transmission to the unicast transmission (for one or more MBSs) , the UE may start monitoring on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the unicast transmission.

The UE may commence its monitoring on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the unicast transmission after a period T2, upon/after receiving the switching indication. The UE may commence its monitoring on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the unicast transmission after a period T2, upon/after the UE stops its monitoring on the other specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the multicast transmission.

The UE may perform BWP switching (after a period T2) , upon/after receiving the switching indication that indicates the transmission mode switching from the multicast transmission to the unicast transmission (for the one or more MBSs) . The UE may perform BWP switching (after a period T2) , upon/after receiving the switching indication that indicates the transmission mode switching from the multicast transmission to the unicast transmission (for the one or more MBSs) . The UE may perform BWP switching (after a period T2) , upon/after transmitting a feedback in response to reception of the switching indication (for the one or more MBSs) from the network. The feedback may be a RRC message, a PDCP status report, a RLC status PDU, a confirmation MAC CE, a HARQ ACK/NACK, etc. The confirmation MAC CE/RRC message may indicate whether the switching indication has been received by the UE. The confirmation MAC CE/RRC message may indicate whether the switching indication corresponding to a specific service has been received by the UE.

The network may configure, to a UE, specific PDCCH (s) /search space (s) that is for scheduling (one or more) MBSs via the multicast transmission on a first BWP, and specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the unicast transmission on a second BWP. If the UE is initially receiving (the one or more) MBSs via the multicast transmission on the first BWP, the UE may perform BWP switching from the first BWP to the second BWP upon/after reception of the switching indication that indicates the transmission mode switching from the multicast transmission to the unicast transmission (for the one or more MBSs) . The switching indication may or may not include the identity of the new BWP (e.g., BWP ID) that the UE may switch to (e.g., the second BWP) .

When the UE receives the switching indication which indicates the transmission mode switching from the multicast transmission to the unicast transmission (for one or more MBSs) , the UE may start monitoring DCI associated with C-RNTI and/or UE-specific RNTI on the specific PDCCH (s) /search space (s) that is for scheduling (the one or more) MBSs via the unicast transmission. When the UE receives the switching indication which indicates the transmission mode switching from the multicast transmission to the unicast transmission (for one or more MBSs) , the UE may start monitoring on the specific PDCCH (s) /search space (s) that is for scheduling new transmission and/or retransmission of (the one or more) MBSs via the multicast transmission. The period T2 may be preconfigured in the UE and/or configured by the network via broadcast system information (e.g., SIB) or dedicated signaling (e.g., RRC signaling) . The period T2 may be in units of symbol, slot, subframe, millisecond, second, etc.

(c) Sending a feedback to the network.

The UE (e.g., MAC entity) may trigger a confirmation MAC CE upon/after receiving the switching indication from the network. The UE may trigger a confirmation MAC CE upon/after receiving the switching indication if the switching indication has at least one specific characteristic. Then, upon the UE (e.g., MAC entity) has an UL resource allocated for new transmission, the UE (e.g., MAC entity) may instruct the Multiplexing and Assembly procedure to generate a confirmation MAC CE for transmission on the UL resource, and cancel the triggered confirmation MAC CE. The switching indication may be considered as having specific characteristics if the switching indication indicates the transmission mode switching from the unicast transmission to the multicast transmission. The switching indication may be considered as having specific characteristics if the switching indication indicates the transmission mode switching from the multicast transmission to the unicast transmission. The switching indication may be considered as having specific characteristics if the switching indication indicates the transmission mode switching of a specific MBS (group) . The specific MBS (group) may be indicated by the network or preconfigured by the UE. The confirmation MAC CE may indicate whether the switching indication has been received by the UE. The confirmation MAC CE may indicate whether the switching indication corresponding to a specific service has been received by the UE. The triggered confirmation MAC CE may be cancelled upon the MAC is reset. The triggered confirmation MAC CE may be cancelled if the MBS corresponding to the switching indication is stopped. The triggered confirmation MAC CE may be cancelled if the UE leaves the area of the MBS corresponding to the switching indication. The triggered confirmation MAC CE may be cancelled if the UE loses interest in the MBS corresponding to the switching indication. The triggered confirmation MAC CE may be cancelled if capability limitations start inhibiting reception of the MBS corresponding to the switching indication.

The UE (e.g., receiving side of an AM RLC entity) may trigger a RLC STATUS reporting upon/after receiving the switching indication from the network. The UE may trigger a RLC STATUS reporting upon/after receiving the switching indication if the received switching indication has at least one specific characteristic. When RLC STATUS reporting has been triggered, the UE (e.g., receiving side of an AM RLC entity) may construct a single RLC STATUS PDU (if the t-StatusProhibit is not running) for transmission in the UL. The pending RLC STATUS report may be dropped/overridden if the PTP transmission for the MBS that corresponds to the switching indication is switched off. The pending RLC STATUS report may be dropped/overridden if the MBS corresponding to the switching indication is stopped. The pending RLC STATUS report may be dropped/overridden if the UE leaves the area of the MBS corresponding to the switching indication. The pending RLC STATUS report may be dropped/overridden if the UE loses interest in the MBS corresponding to the switching indication. The pending RLC STATUS report may be dropped/overridden if capability limitations start inhibiting reception of the MBS corresponding to the switching indication.

The UE (e.g., receiving PDCP entity) may trigger a PDCP status reporting upon/after receiving the switching indication from the network (if the UE is configured to send a PDCP status report) . The UE may trigger a PDCP status report upon/after receiving the switching indication if the switching indication has at least one specific characteristic. When PDCP status reporting has been triggered, the UE (e.g., receiving PDCP entity) may compile a PDCP status report for transmission in the UL. The triggered PDCP status report may be cancelled if the MBS corresponding to the switching indication is stopped. The triggered PDCP status report may be cancelled if the MBS corresponding to the switching indication is stopped. The triggered PDCP status report may be cancelled if the UE leaves the area of the MBS corresponding to the switching indication. The triggered PDCP status report may be cancelled if the UE loses interest in the MBS corresponding to the switching indication. The triggered PDCP status report may be cancelled if capability limitations start inhibiting reception of the MBS corresponding to the switching indication.

The UE (e.g., RRC entity) may initiate a procedure to send a RRC confirmation message upon/after receiving the switching indication from the network. The UE may initiate the procedure upon/after receiving the switching indication if the switching indication has at least one specific characteristic. When the procedure has been initiated, the UE (e.g., RRC entity) may send the RRC confirmation message to the network. The RRC confirmation message may indicate whether the switching indication has been received by the UE. The RRC confirmation message may indicate whether the switching indication corresponding to a specific service has been received by the UE. The RRC confirmation message may be the UE assistance information. The UE may stop the CORESET/PDCCH/search space monitoring for the UE’s group RNTI upon receiving PDCCH/SS reconfiguration. The UE may stop the CORESET/PDCCH/search space monitoring for the UE’s group RNTI upon receiving MBS change notification.

FIG. 4 is a flowchart illustrating a method 400 performed by a UE for handling reception of Multicast-Broadcast Service (MBS) according to an example implementation of the present disclosure. Although

actions

402, 404, 406 and 408 are illustrated as separate actions represented as independent blocks in FIG. 4, these separately illustrated actions should not be construed as necessarily order dependent. The order in which the actions are performed in FIG. 4 is not intended to be construed as a limitation, and any number of the disclosed blocks may be combined in any order to implement the method, or an alternate method. Moreover, each of

actions

402, 404, 406 and 408 may be performed independent of other actions and can be omitted in some implementations of the present disclosure.

In action 402, the UE may receive at least one of a first downlink (DL) assignment and a second DL assignment for scheduling a first MBS corresponding to a first MBS Radio Bearer (MRB) . The first DL assignment may be associated with a first Group-Radio Network Temporary Identifier (G-RNTI) for the first MRB and the second DL assignment may be associated with a Cell-Radio Network Temporary Identifier (C-RNTI) of the UE. The first DL assignment associated with the first G-RNTI may be used for the first MBS (corresponding to the first MRB) for point-to-multipoint (PTM) transmission, and the second DL assignment associated with the C-RNTI of the UE may be used for the first MBS (corresponding to the first MRB) for point-to-point (PTP) transmission. The first MRB may correspond to a first Packet Data Convergence Protocol (PDCP) entity and at least one of a first Radio Link Control (RLC) entity configured for point-to-multipoint (PTM) transmission and a second RLC entity configured for point-to-point (PTP) transmission.

In action 404, the UE may receive data of the first MBS based on the at least one of the first DL assignment and the second DL assignment.

In action 406, the UE may receive a switching indication from a network. The switching indication may be a Radio Resource Control (RRC) message, a Medium Access Control (MAC) Control Element (CE) , or Downlink Control Information (DCI) . The UE may transmit an uplink (UL) feedback in response to reception of the switching indication. The UL feedback may be a Packet Data Convergence Protocol (PDCP) status report, and the PDCP status report may be transmitted from a PDCP entity of the UE that corresponds to the first MRB.

In action 408, the UE may determine, based on the switching indication, whether to stop or start receiving the at least one of the first DL assignment and the second DL assignment. The UE may start receiving the first DL assignment in a case that only the second DL assignment is received, and the switching indication indicates the transmission mode of the first MBS is switched, and the UE may start receiving the second DL assignment in a case that only the first DL assignment is received and the switching indication indicates the transmission mode of the first MBS is switched. In some implementations, the UE may determine, based on the switching indication, whether to stop or start monitoring at least one of a first search space and a second search space, and the first search space is for receiving the first DL assignment and the second search space is for receiving the second DL assignment. In some implementations, the UE may stop receiving the first DL assignment in a case that the first MRB corresponds to the PDCP entity, the first RLC entity and the second RLC entity, and the switching indication indicates the first RLC entity is released, and the UE may start receiving the first DL assignment in a case that the first MRB corresponds to the PDCP entity and the second RLC entity, and the switching indication indicates the first RLC entity is configured for the first MRB.

The method 400 provided in the present disclosure allows the network to dynamically control the UE’s behavior on DL assignment monitoring/search space monitoring of an MBS. It is beneficial to provide scheduling flexibility to the network. Moreover, based on the switching indication introduced in the method 400, the UE may start/stop its PDCCH/search space monitoring for PTP transmission and/or PTM transmission of an MBS. The power consumption of the UE may thus be reduced.

FIG. 5 is a flowchart illustrating a method 500 performed by a UE for handling reception of Multicast-Broadcast Service (MBS) according to another example implementation of the present disclosure. Although

actions

502, 504, 506, 510, 512 and 514 are illustrated as separate actions represented as independent blocks in FIG. 5, these separately illustrated actions should not be construed as necessarily order dependent. The order in which the actions are performed in FIG. 5 is not intended to be construed as a limitation, and any number of the disclosed blocks may be combined in any order to implement the method, or an alternate method. Moreover, each of

actions

502, 504, 506, 510, 512 and 514 may be performed independent of other actions and can be omitted in some implementations of the present disclosure.

Actions

502, 504 and 506 respectively correspond to

actions

402, 404 and 406 illustrated in FIG. 4.

In action 510, the UE may receive at least one of a third DL assignment and a fourth DL assignment for scheduling a second MBS corresponding to a second MRB. The third DL assignment may be associated with a second G-RNTI for the second MRB and the fourth DL assignment may be associated with the C-RNTI of the UE. The third DL assignment associated with the second G-RNTI may be used for the second MBS (corresponding to the second MRB) for point-to-multipoint (PTM) transmission, and the fourth DL assignment associated with the C-RNTI of the UE may be used for the second MBS (corresponding to the second MRB) for point-to-point (PTP) transmission. The second MRB may correspond to a second PDCP entity and at least one of a third RLC entity configured for PTM transmission and a fourth RLC entity configured for PTP transmission.

In action 512, the UE may receive data of the second MBS based on the at least one of the third DL assignment and the fourth DL assignment.

In action 514, the UE may determine, based on the switching indication, whether to stop or start receiving the at least one of the first DL assignment and the second DL assignment, and the at least one of the third DL assignment and the fourth DL assignment. The UE may stop receiving the first DL assignment and the third DL assignment in a case that the first MRB corresponds to the first PDCP entity, the first RLC entity and the second RLC entity, the second MRB corresponds to the second PDCP entity, the third RLC entity and the fourth RLC entity, and the switching indication indicates the first RLC entity and the third RLC entity are released. The UE may start receiving the first DL assignment and the third DL assignment in a case that the first MRB corresponds to the first PDCP entity and the second RLC entity, the second MRB corresponds to the second PDCP entity and the fourth RLC entity, and the switching indication indicates the first RLC entity is configured for the first MRB and the third RLC entity is configured for the second MRB.

The method 500 provided in the present disclosure allows the network to dynamically control the UE’s behavior on DL assignment monitoring/search space monitoring of more than one MBS. It is beneficial to provide scheduling flexibility to the network. Moreover, based on the switching indication introduced in the method 500, the UE may start/stop its PDCCH/search space monitoring for PTP transmission and/or PTM transmission of more than one MBS. The power consumption may thus be reduced.

FIG. 6 is a block diagram illustrating a node 600 for wireless communication according to an example implementation of the present disclosure. As illustrated in FIG. 6, a node 600 may include a transceiver 620, a processor 628, a memory 634, one or more presentation components 638, and at least one antenna 636. The node 600 may also include a radio frequency (RF) spectrum band module, a BS communications module, a network communications module, and a system communications management module, Input /Output (I/O) ports, I/O components, and a power supply (not illustrated in FIG. 6) .

Each of the components may directly or indirectly communicate with each other over one or more buses 640. The node 600 may be a UE or a BS that performs various functions disclosed with reference to FIG. 4 and FIG. 5.

The transceiver 620 has a transmitter 622 (e.g., transmitting/transmission circuitry) and a receiver 624 (e.g., receiving/reception circuitry) and may be configured to transmit and/or receive time and/or frequency resource partitioning information. The transceiver 620 may be configured to transmit in different types of subframes and slots including but not limited to usable, non-usable and flexibly usable subframes and slot formats. The transceiver 620 may be configured to receive data and control channels.

The node 600 may include a variety of computer-readable media. Computer-readable media may be any available media that may be accessed by the node 600 and include volatile (and/or non-volatile) media and removable (and/or non-removable) media.

The computer-readable media may include computer-storage media and communication media. Computer-storage media may include both volatile (and/or non-volatile media) , and removable (and/or non-removable) media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules or data.

Computer-storage media may include RAM, ROM, EPROM, EEPROM, flash memory (or other memory technology) , CD-ROM, Digital Versatile Disks (DVD) (or other optical disk storage) , magnetic cassettes, magnetic tape, magnetic disk storage (or other magnetic storage devices) , etc. Computer-storage media may not include a propagated data signal. Communication media may typically embody computer-readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanisms and include any information delivery media.

The term “modulated data signal” may mean a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. Communication media may include wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared and other wireless media. Combinations of any of the previously listed components may also be included within the scope of computer-readable media.

The memory 634 may include computer-storage media in the form of volatile and/or non-volatile memory. The memory 634 may be removable, non-removable, or a combination thereof. Example memory may include solid-state memory, hard drives, optical-disc drives, etc. As illustrated in FIG. 6, the memory 634 may store a computer-readable and/or computer-executable program 632 (e.g., software codes) that are configured to, when executed, cause the processor 628 to perform various functions disclosed herein, for example, with reference to FIG. 4 and FIG. 5. Alternatively, the program 632 may not be directly executable by the processor 528 but may be configured to cause the node 600 (e.g., when compiled and executed) to perform various functions disclosed herein.

The processor 628 (e.g., having processing circuitry) may include an intelligent hardware device, e.g., a Central Processing Unit (CPU) , a microcontroller, an ASIC, etc. The processor 628 may include memory. The processor 628 may process the data 630 and the program 632 received from the memory 634, and information transmitted and received via the transceiver 620, the base band communications module, and/or the network communications module. The processor 628 may also process information to send to the transceiver 620 for transmission via the antenna 636 to the network communications module for transmission to a CN.

One or more presentation components 638 may present data indications to a person or another device. Examples of presentation components 638 may include a display device, a speaker, a printing component, a vibrating component, etc.

In view of the present disclosure, it is obvious that various techniques may be used for implementing the disclosed concepts without departing from the scope of those concepts. Moreover, while the concepts have been disclosed with specific reference to certain implementations, a person of ordinary skill in the art may recognize that changes may be made in form and detail without departing from the scope of those concepts. As such, the disclosed implementations are to be considered in all respects as illustrative and not restrictive. It should also be understood that the present disclosure is not limited to the particular implementations disclosed and many rearrangements, modifications, and substitutions are possible without departing from the scope of the present disclosure.

Claims

A method performed by a user equipment (UE) for handling reception of Multicast-Broadcast Service (MBS) , the method comprising:

receiving at least one of a first downlink (DL) assignment and a second DL assignment for scheduling a first MBS corresponding to a first MBS Radio Bearer (MRB) , the first DL assignment being associated with a first Group-Radio Network Temporary Identifier (G-RNTI) for the first MRB and the second DL assignment being associated with a Cell-Radio Network Temporary Identifier (C-RNTI) of the UE;

receiving data of the first MBS based on the at least one of the first DL assignment and the second DL assignment;

receiving a switching indication from a network; and

determining, based on the switching indication, whether to stop or start receiving the at least one of the first DL assignment and the second DL assignment.
The method of claim 1, further comprising:

determining, based on the switching indication, whether to stop or start monitoring at least one of a first search space for receiving the first DL assignment and a second search space for receiving the second DL assignment.
The method of claim 1, further comprising:

transmitting an uplink (UL) feedback in response to reception of the switching indication.
The method of claim 3, wherein the UL feedback is a Packet Data Convergence Protocol (PDCP) status report, and the PDCP status report is transmitted from a PDCP entity of the UE that corresponds to the first MRB.
The method of claim 1, wherein the switching indication is a Radio Resource Control (RRC) message, a Medium Access Control (MAC) Control Element (CE) , or Downlink Control Information (DCI) .
The method of claim 1, wherein the first MRB corresponds to a Packet Data Convergence Protocol (PDCP) entity and at least one of a first Radio Link Control (RLC) entity configured for point- to-multipoint (PTM) transmission and a second RLC entity configured for point-to-point (PTP) transmission, and the method further comprises:

stopping receiving the first DL assignment in a case that the first MRB corresponds to the PDCP entity and the first RLC entity and the second RLC entity, and the switching indication indicates the first RLC entity is released; and

starting receiving the first DL assignment in a case that the first MRB corresponds to the PDCP entity and the second RLC entity, and the switching indication indicates the first RLC entity is configured for the first MRB.
The method of claim 1, further comprises:

starting receiving the first DL assignment in a case that only the second DL assignment is received, and the switching indication indicates the transmission mode of the first MBS is switched; and

starting receiving the second DL assignment in a case that only the first DL assignment is received, and the switching indication indicates the transmission mode of the first MBS is switched.
The method of claim 1, further comprising:

receiving at least one of a third DL assignment and a fourth DL assignment for scheduling a second MBS corresponding to a second MRB, the third DL assignment being associated with a second G-RNTI for the second MRB and the fourth DL assignment being associated with the C-RNTI of the UE;

receiving data of the second MBS based on the at least one of the third DL assignment and the fourth DL assignment; and

determining, based on the switching indication, whether to stop or start receiving the at least one of the third DL assignment and the fourth DL assignment.
The method of claim 8, wherein:

the first MRB corresponds to a first Packet Data Convergence Protocol (PDCP) entity and at least one of a first Radio Link Control (RLC) entity configured for point-to-multipoint (PTM) transmission and a second RLC entity configured for point-to-point (PTP) transmission, and

the second MRB corresponds to a second PDCP entity and at least one of a third RLC entity configured for PTM transmission and a fourth RLC entity configured for PTP transmission, and the method further comprises:

stopping receiving the first DL assignment and the third DL assignment in a case that the first MRB corresponds to the first PDCP entity and the first RLC entity and the second RLC entity, the second MRB corresponds to the second PDCP entity and the third RLC entity and the fourth RLC entity, and the switching indication indicates the first RLC entity and the third RLC entity are released, and

starting receiving the first DL assignment and the third DL assignment in a case that the first MRB corresponds to the first PDCP entity and the second RLC entity, the second MRB corresponds to the second PDCP entity and the fourth RLC entity, and the switching indication indicates the first RLC entity is configured for the first MRB and the third RLC entity is configured for the second MRB.
A user equipment (UE) for handling reception of Multicast-Broadcast Service (MBS) , the UE comprising:

a processor; and

a memory coupled to the processor, wherein the memory stores a computer-executable program that when executed by the processor, causes the processor to perform the method of any of claims 1 to 9.