TWI792614B - Methods and apparatus for multicast and broadcast service - Google Patents

Abstract

Apparatus and methods are provided for multicast and broadcast service. The method can include configuring, by a user equipment (UE), a multicast radio bearer (MRB) for one or more multicast and broadcast services (MBSs) in a wireless network, wherein an MRB configuration enables feedback for the one or more MBSs; establishing the MRB and a UE protocol stack for an active MBS based on the MRB configuration upon detecting one or more activation conditions, wherein the MRB is associated with one or two channels comprising a multicast channel and a unicast channel; receiving data packets of the active MBS through the established MRB in a multi-cast service area comprising one or more serving cells; reconfiguring the MRB to change a type of the MRB upon detecting one or more reconfiguration conditions; and releasing the MRB upon detecting one or more releasing conditions..

Description

Method and user equipment for multicast broadcast service

The present invention relates generally to wireless communications and, more particularly, to reliable multicast transmission over multicast radio bearers (MRBs).

With the exponential growth of wireless data services, the delivery of content to a large mobile user base is growing rapidly. Initial wireless multicast/broadcast services include streaming services such as mobile TV and IPTV. With the ever-increasing demand for large group content delivery, the latest application development of mobile multicast services requires highly robust and critical communication services, such as group communication in disaster situations, and the necessity of multicast services related to public safety networks. Early 3GPP defined enhanced multimedia broadcast multicast service (eMBMS) in LTE standard, defined single-cell point to multipoint (single-cell point to multipoint, SC-PTM) service and multicast broadcast Single-frequency network (multicast-broadcast single-frequency network, MBSFN). 5G multicast and broadcast service (MBS) is defined based on the unicast 5G core (5G core, 5GC) architecture. Various applications may rely on multicast transported communications, such as live streaming, video distribution, vehicle-to-everything (V2X) communications, public safety (PS) communications, file downloads, etc. In some cases, the cellular system may need to enable reliable multicast transmission to guarantee the reception quality at the UE side. The reliable transmission of some multicast services in the NR system requires feedback on the reception of the multicast transmission, which helps the network to retransmit the necessary content to the UE.

Improvements and enhancements are needed to support reliable multicast transmission and reception over MRBs.

An embodiment of the present invention provides a method for MBS, including: UE configures MRB for one or more MBSs in a wireless network, wherein the MRB configuration enables feedback to the one or more MBSs; When one or more start conditions, based on the MRB configuration, establish the MRB and user equipment protocol stack for the active MBS, wherein the MRB is associated with one or two channels including a multicast channel and a unicast channel; receiving data packets of said active MBS via said MRB established in a multicast service area comprising one or more serving cells; reconfiguring said MRB upon detection of one or more reconfiguration conditions to change said MRB and release the MRB when one or more release conditions are detected.

Another embodiment of the present invention provides a user equipment, including: a transceiver, used to send and receive radio frequency signals in a wireless network; an MRB configuration module, used to configure an MRB in the wireless network for one or A plurality of MBSs, wherein the MRB configuration enables feedback to the one or more MBSs; the MRB control module is used to establish the MRB and the active MBS based on the MRB configuration when one or more activation conditions are detected. User equipment protocol stacking, wherein the MRB is associated with one or two channels including a multicast channel and a unicast channel; the MRB receiving module is used to pass in a multicast service area including one or more service cells The established MRB receives the data packet of the active MBS; the MRB reconfiguration module is used to reconfigure the MRB when one or more reconfiguration conditions are detected, so as to change the type of the MRB; and MRB release A module that releases the MRB when one or more release conditions are detected.

Reference will now be made in detail to some embodiments of the invention, examples of which are illustrated in the accompanying drawings.

The present invention provides methods, devices, processing systems and computer-readable media for new radio (new radio, NR) access technology or 5G technology or other radio access technologies. NR, etc. can support various wireless communication services, such as enhanced mobile broadband for wide bandwidth, millimeter wave for high carrier frequency, large-scale MTC for non-backward compatible machine type communication (MTC) technology and/or for Mission-critical ultra-reliable low-latency communications. These services may have latency and reliability requirements. These services may also have different transmission time intervals (transmission time interval, TTI) to meet their respective quality of service (quality of service, QoS) requirements. Also, these services may co-exist in the same subframe.

FIG. 1 is a schematic system diagram of a wireless communication network supporting reliable multicast transmission for multicast services according to an embodiment of the present invention. Wireless communication network 100 includes one or more fixed infrastructure elements forming a network distributed over a geographical area. An infrastructure unit may also be called an access point, access terminal, base station, Node-B, evolved Node-B (eNode-B), next-generation Node-B (gNB), or other terminology used in the art. A base station may serve multiple mobile stations within a service area (eg, a cell or a magnetic sector of a cell), for example, a cell, or a magnetic sector of a cell. In some systems, one or more base stations are coupled to the controller to form an access network coupled to one or more core networks, the access network being coupled to one or more core networks. gNB 106, gNB 107 and gNB 108 are base stations in the wireless network, and their service areas may or may not overlap with each other. In one embodiment, a user equipment (UE) or mobile station 101 is located in a service area covered by gNB 106 and gNB 107 . As an example, UE or mobile station 101 is only located in the service area of gNB 106 and is connected to gNB 106. A UE or mobile station 102 is only located in the service area of the gNB 107 and is connected to the gNB 107 . The gNB 106 is connected to the gNB 107 through the Xn interface 121 . The gNB 106 is connected to the gNB 108 through the Xn interface 122 . The 5G network entity 109 is connected to gNBs 106, 107 and 108 via NG connections 131, 132 and 133, respectively. In one embodiment, gNB 106 and gNB 107 provide the same MBMS service. Service continuity is guaranteed during handover when UE 101 moves from gNB 106 to gNB 107 and vice versa. The area covered by gNBs 106 and 107 with the same MBMS service is a multicast service area for MBMS service.

FIG. 1 further shows a simplified block diagram of a base station and a mobile device/UE for multicast transmission. The gNB 106 has an antenna 156, which transmits and receives radio signals. The RF transceiver circuit 153 coupled to the antenna receives RF signals from the antenna 156 , converts the RF signals to baseband signals, and sends the baseband signals to the processor 152 . The RF transceiver 153 also converts the baseband signal received from the processor 152 to an RF signal and sends it to the antenna 156 . The processor 152 processes the received baseband signals, and invokes various functional modules to perform functions in the gNB 106 . Memory 151 stores program instructions and data 154 to control the operation of gNB 106 . The gNB 106 also includes a set of control modules 155 for performing functional tasks to communicate with mobile stations. These control modules can be implemented by circuits, software, firmware or a combination of the above.

FIG. 1 also includes a simplified block diagram of a UE, such as UE 101 . The UE has an antenna 165 that transmits and receives radio signals. The RF transceiver circuit 163 coupled to the antenna receives RF signals from the antenna 165 , converts the RF signals to baseband signals, and sends the baseband signals to the processor 162 . In one embodiment, the RF transceiver 163 may include two RF modules (not shown) for transmitting and receiving in different frequency bands. The RF transceiver 163 also converts the baseband signal received from the processor 162 to an RF signal and sends it to the antenna 165 . The processor 162 processes the received baseband signals and invokes various functional modules to perform functions in the UE 101 . The memory 161 stores program instructions and data 164 to control the operation of the UE 101. Antenna 165 sends uplink transmissions to antenna 156 of gNB 106 and receives downlink transmissions from antenna 156 of gNB 106 .

UE 101 also includes a set of control modules for performing functional tasks. These control modules can be implemented by circuits, software, firmware or a combination of the above. The MRB configuration module 191 configures MRBs for one or more MBSs in the wireless network, wherein the MRB configuration enables feedback to one or more MBSs. The MRB control module 192 establishes the MRB and UE protocol stack for the active MBS based on the MRB configuration when one or more start conditions are detected, wherein the MRB is associated with one or two channels including a multicast channel and a unicast channel couplet. The MRB receiving module 193 receives data packets of active MBSs through established MRBs in a multicast service area including one or more serving cells. The MRB release module 194 releases the MRB when one or more release conditions are detected. The MRB reconfiguration module 195 reconfigures the MRB upon detection of one or more reconfiguration conditions. In an embodiment, the UE also has a radio resource control (radio resource control, RRC) state controller 197 , an MBS controller 198 and a protocol stack controller 199 . The RRC state controller 197 controls the UE RRC state according to commands from the network and UE conditions. RRC supports the following states: RRC Idle (RRC_IDLE), RRC Connected (RRC_CONNECTED) and RRC Inactive (RRC_INACTIVE). In one embodiment, the UE can receive the multicast broadcast service in the RRC idle/RRC inactive state. The UE applies the MRB establishment procedure to start a session receiving the service it is interested in. The UE applies the MRB release process and stops receiving the session. The MBS controller 198 controls the establishment/addition, reconfiguration/modification and release/removal of MRBs based on different sets of conditions for MRB establishment, reconfiguration and release. Protocol stack controller 199 manages adding, modifying or removing protocol stacks for MRBs. The protocol stack includes packet data convergence protocol (PDCP) layer 182, radio link control (radio link control, RLC) layer 183, media access control (media access control, MAC) layer 184 and physical (PHY) Layer 185. In one embodiment, the service data adaptation protocol (service data adaptation protocol, SDAP) layer 181 is an optional configuration. In one embodiment, the RLC layer 183 supports automatic repeat request (automatic repeat request, ARQ) error correction, segmentation and reassembly, re-segmentation, repetition detection, reconstruction and other functions. In an embodiment, a new procedure for RLC reconfiguration is performed, which can reconfigure RLC entities associated to one or two logical channels. In another embodiment, the MAC layer 184 supports mapping between logical channels and transport channels, multiplexing, demultiplexing, hybrid automatic repeat request (hybrid automatic repeat request, HARQ), radio resource selection, and the like.

FIG. 2 is a schematic diagram of an exemplary NR wireless system with a centralized upper layer of an NR radio interface stack according to an embodiment of the present invention. There may be different protocol division options between the central unit (CU)/gNB node upper layer (upper layer) and distributed unit (DU)/gNB node lower layer (lower layer). The functional division between the central unit and gNB lower layers may depend on the transport layer. Since higher protocol layers have lower performance requirements on the transport layer in terms of bandwidth, latency, synchronization, and jitter, low-performance transport between the central unit and lower gNB layers can enable high protocol layers of the NR radio stack in the central unit get support. In one embodiment, the SDAP and PDCP layers are located in the central unit, while the RLC, MAC and physical layers are located in the distributed units. A core unit 201 is connected to a central unit 211 with a gNB upper layer 252 . In an embodiment, the gNB upper layer 252 includes a PDCP layer and an optional SDAP layer. The central unit 211 is connected to decentralized units 221, 222 and 223, wherein the distributed units 221, 222 and 223 correspond to the cells 231, 232 and 233, respectively. The distributed units 221 , 222 and 223 include a gNB lower layer 251 . In one embodiment, gNB lower layer 251 includes PHY, MAC and RLC layers. In another embodiment 260, each gNB has a protocol stack 261 comprising SDAP, PDCP, RLC, MAC and PHY layers.

FIG. 3 is an exemplary diagram of different MRB configurations for supporting reliable MBS according to an embodiment of the present invention. MRB provides a multicast service, which is only provided by a multicast traffic channel (multicast traffic channel, MTCH) with UE protocol stack 302, only by a dedicated traffic channel (dedicated traffic channel, DTCH) with UE protocol stack 303, or with UE protocol Both MTCH and DTCH of the stack 301 are carried. In an embodiment 320, MRB 321 is configured to be associated with MTCH. In an embodiment 330, MRB 331 is configured to be associated with DTCH. In an embodiment 310, MRB 311 is configured to be associated with MTCH and DTCH. To support downlink over-the-air multicast transmissions, one or more multicast MRBs are established to correspond to the multicast streams of a particular multicast session. The MRB can perform point-to-multipoint (point-to-multipoint, PTM) transmission, point-to-point (point-to-point, PTP) transmission and a combination of PTM and PTP transmission in the cell. Different configurations can be described as different transmission modes/lanes/MRB types. In an embodiment 310 with a split MRB configuration, the MRB is configured with a PTM 312 leg and a PTP 313 leg. In another embodiment 320 of the MTCH-only MRB configuration, the MRB is configured with only the PTM leg 322 and the PTP leg 323 is not configured or enabled/established for the MTCH-only MRB configuration. In yet another embodiment 330 of the DTCH-only MRB configuration, the MRB is configured with only the PTP branch 333, and the PTM branch 332 is not configured or enabled/established for the DTCH-only MRB configuration.

In some systems, such as NR systems, NR multicast/broadcast is transmitted within the coverage area of a cell. In one embodiment, a multicast control channel (MCCH) provides information on the NR multicast/broadcast service list for ongoing sessions transmitted on the MTCH. At the physical layer, the MTCH is scheduled by the gNB in the search space of the physical downlink control channel (PDCCH), which is scrambled by the group radio network temporary identification (G-RNTI). The UE decodes the MTCH data of the multicast session in the multicast physical downlink shared channel (PDSCH). In legacy systems supporting MBMS/eMBMS, the radio bearer structure for multicast and broadcast transmissions is modeled independently of unicast transmissions. Due to the unidirectional transmission of traditional MBMS/eMBMS services, the transmission of multicast/broadcast sessions adopts the RLC unacknowledged mode (unacknowledged mode, UM). In this case, no interaction between multicast and unicast is required for a particular UE in RRC connected state. For NR networks, reliable transmission is required to provide new services through MBS. Traditional multicast transmissions do not guarantee successful reception by all UEs unless very conservative link adaptation is done, which greatly reduces resource efficiency. To support reliable multicast transmission of MBS, each UE receiving the service needs a feedback channel in the uplink. The receiving UE can use the feedback channel to feed back its reception status about the service to the network, and the network can perform necessary retransmission according to the feedback to improve transmission reliability. From the perspective of uplink feedback, the feedback channel can be used for layer 2 (layer 2, L2) feedback, such as RLC status report and/or PDCP status report. In addition, the feedback channel can be used for HARQ feedback. Furthermore, feedback should be a bi-directional channel between the UE and the network, assuming the network can use this channel to perform the required packet retransmissions. Packet retransmissions are L2 retransmissions (such as RLC retransmissions and/or PDCP retransmissions). In addition, the feedback channel can be used for HARQ retransmission.

FIG. 4 is a schematic diagram of a protocol stack with MRB configuration based on PDCP retransmission according to an embodiment of the present invention. In PDCP-based retransmission 490, there is one PDCP entity 491 per MRB. Two logical channels (i.e. MTCH and DTCH) are associated with PDCP entities, and each logical channel corresponds to one RLC entity. The RLC entity 492 corresponds to the MTCH, and the RLC entity 493 corresponds to the DTCH. From UE perspective, PDCP status report triggering PDCP retransmission is passed to RLC entity 493 corresponding to DTCH. From a network point of view, the PDCP protocol data unit (protocol data unit, PDU) for retransmission is delivered through DTCH. The MAC entity 494 respectively maps the logical channels MTCH and DTCH to two transmission channels: a multicast channel (multicast channel, MCH) and a downlink shared channel (downlink shared channel, DL-SCH). The UE monitors two independent transmission channels through different radio network temporary identification (RNTI). Robust header compression (robust header compression, ROHC) and security features are optional for multicast transmissions. The RLC layer only includes segmentation, and the ARQ function of the RLC layer is moved to the PDCP layer. RLC 492 and RLC 493 map to MAC entity 494 and are used to send data packets to PHY 495.

A network entity such as a base station/gNB transmits MBS data packets to N UEs over the PTM link and retransmits the MBS data packets over the PTP link associated with the PDCP protocol stack based on feedback. Correspondingly, a UE configured with a stack based on the PDCP protocol receives an MBS data packet from the base station on the PTM RB and sends a feedback to the base station. Multicast is scheduled independently of PTP transport. The protocol stack of the base station and UE includes SDAP layer 401 , PDCP layer 402 , RLC layer 403 and MAC layer 404 . SDAP layer 401 processes QoS flow 481 , including QoS flow processing 411 at the base station for UE-1 and QoS flow processing 412 for UE-N, and QoS flow processing 413 at UE for UE. The PDCP layer 402 includes ROHC functions and security functions. ROHC functionality and security functionality are optional for multicast transmission. The PDCP layer 402 includes ROHC 421 and security 424 for UE-1 multicast at the base station, ROHC 4212 and security 4242 for UE-1 unicast, ROHC 422 and security 425 for UE-N multicast, The functions of ROHC 4222 and security 4252 for UE-N unicast, and the functions of ROHC 423 and security 426 at UE. RB 482 is processed in PDCP layer 402 . The RLC layer 403 includes segmentation and ARQ functions at the base station, including segmentation and ARQ 431 for UE-1 multicast, segmentation and ARQ 432 for UE-1 unicast, Segmentation and ARQ 433 for UE-N unicast 434; and segmentation and ARQ functions at UE, including segmentation and ARQ 435 for unicast channels, and for multicast channels Segmentation and ARQ 436. The RLC channel 483 is handled in the RLC layer 403 . The MAC layer 404 includes functions for scheduling and priority processing 441 at the base station, multiplexing 443 and HARQ 446 for UE-1 at the base station, multiplexing 444 and HARQ 447 for UE-N; Scheduling and prioritization 442 for UEs, multiplexing 445 and HARQ 448 functions for UEs. The MAC layer 404 handles logical lanes 484 and transport lanes 485 .

FIG. 5 is a schematic diagram of a protocol stack with RLC retransmission-based MRB configuration according to an embodiment of the present invention. In RLC-based retransmission 590 , one PDCP entity 591 , one RLC entity 592 , one MAC entity 593 and one PHY entity 594 corresponding to each MRB are included. The RLC entity 592 is associated to two logical channels, MTCH and DTCH. From the perspective of the UE, the RLC status report that triggers the RLC retransmission is transmitted through the DTCH. From a network point of view, RLC PDUs that need to be retransmitted are delivered via DTCH. The MAC entity 594 maps logical channels MTCH and DTCH to two transport channels: MCH and DL-SCH, respectively. The UE monitors two independent transmission channels through different RNTIs.

A network entity such as a base station/gNB transmits MBS data packets with PTM RBs to N UEs and retransmits MBS data packets on PTP RBs associated with the RLC protocol stack based on feedback. Correspondingly, the UE configured with stacking based on the RLC protocol receives the MBS data packet from the base station on the PTM RB and sends a feedback to the base station. Multicast is scheduled independently of PTP transport. The protocol stack of the base station and UE includes SDAP layer 501 , PDCP layer 502 , RLC layer 503 and MAC layer 504 . SDAP layer 501 processes QoS flow 581 , including QoS flow processing 511 at base station for UE-1 and QoS flow processing 512 for UE-N, and QoS flow processing 513 at UE for UE. The PDCP layer 502 includes ROHC functions and security functions. ROHC functionality and security functionality are optional for multicast transmission. PDCP layer 502 includes ROHC 521 and security 524 for UE-1 multicast at the base station, ROHC 5212 and security 5242 for UE-1 unicast, ROHC 522 and security 525 for UE-N multicast, Functions of ROHC 5222 and security 5252 for UE-N unicast, and functions of ROHC 523 and security 526 at UE. RB 582 is processed in PDCP layer 502 . The RLC layer 503 includes segmentation and ARQ functions at the base station, including segmentation and ARQ 531 for UE-1 multicast, segmentation and ARQ 532 for UE-1 unicast, Segmentation and ARQ 533 for UE-N unicast, Segmentation and ARQ 534 for UE-N unicast; and Segmentation and ARQ 535 at UE. The RLC channel 583 is handled in the RLC layer 503 . The MAC layer 504 includes functions for scheduling and priority processing 541 at the base station, multiplexing 543 and HARQ 546 for UE-1 at the base station, multiplexing 544 and HARQ 547 for UE-N; Scheduling and prioritization 542 for UEs, multiplexing 545 and HARQ 548 functions for UEs. The MAC layer 504 handles logical lanes 584 and transport lanes 585 .

FIG. 6 is a schematic diagram of a protocol stack with MAC retransmission-based MRB configuration according to an embodiment of the present invention. In MAC-based retransmission 690 , one PDCP entity 691 , one RLC entity 692 , one MAC entity 694 and one PHY entity 695 corresponding to each MRB are included. The RLC entity 692 is associated to one logical channel, ie MTCH. The MAC entity 694 maps logical channels MTCH to MCH and DL-SCH. The MCH is used for the initial transmission and optional retransmission of a transmission block (TB). DL-SCH is used for retransmission of TB. From the perspective of the UE, the HARQ feedback that triggers the HARQ retransmission is transmitted through the UL-SCH. From a network point of view, TBs that need to be retransmitted are delivered via DL-SCH. The UE monitors two independent transmission channels through different RNTIs.

A network entity such as a base station/gNB transmits MBS data packets with PTM RBs to N UEs and retransmits MBS data packets on PTP RBs associated with the MAC protocol stack based on feedback. Correspondingly, the UE configured with stacking based on the MAC protocol receives the MBS data packet from the base station on the PTM RB and sends a feedback to the base station. Multicast is scheduled independently of PTP transport. The protocol stack of the base station and UE includes SDAP layer 601 , PDCP layer 602 , RLC layer 603 and MAC layer 604 . SDAP layer 601 processes QoS flow 681 , including QoS flow processing 611 for UE-1 at the base station, QoS flow processing 612 for UE-N at the base station, and QoS flow processing 613 at the UE for UE. The PDCP layer 602 includes ROHC functions and security functions. ROHC functionality and security functionality are optional for multicast transmission. PDCP layer 602 includes ROHC 621 and security 624 for UE-1 multicast at the base station, ROHC 6212 and security 6242 for UE-1 unicast, ROHC 622 and security 625 for UE-N multicast, The functions of ROHC 6222 and security 6252 for UE-N unicast, and the functions of ROHC 623 and security 626 at UE. RB 682 is processed in PDCP layer 602 . The RLC layer 603 includes segmentation and ARQ functions at the base station, including segmentation and ARQ 631 for UE-1 multicast, segmentation and ARQ 632 for UE-1 unicast, Segmentation and ARQ 633 for UE-N unicast; Segmentation and ARQ 634 for UE-N unicast; and Segmentation and ARQ 635 at UE. The RLC channel 683 is handled in the RLC layer 603 . The MAC layer 604 includes the functions of scheduling and prioritization 641 at the base station, multiplexing 643 and HARQ 646 for UE-1 at the base station, multiplexing 644 and HARQ 647 for UE-N at the base station. The MAC layer 604 handles logical lanes 684 and transport lanes 685 .

FIG. 7 is a schematic diagram of a table for establishing MRB configurations for different retransmission configurations according to an embodiment of the present invention. The MRB can be configured as a separate MRB 701 with both MTCH and DTCH, or as an MTCH MRB 702 with only MTCH activation/establishment, or as a DTCH MRB 703 with only DTCH activation/establishment. MRBs may be configured as PDCP-based 710 , RLC-based 720 and MAC-based 730 based on the retransmission layer. PDCP-based retransmission 710 enables retransmission processing at the PDCP layer to enhance reliability. In an embodiment, the PCDP based MRB is configured as a split MRB with a PDCP entity 711, two RLC entities 714 and 715 associated with MTCH and DTCH respectively. A PCDP-based MRB may be configured or established as an MTCH-only MRB, with a PDCP entity 712 and an RLC entity 716 associated with MTCH. In MTCH-only mode, the RLC entity 717 associated with DTCH is either not configured or not activated/established. A PCDP based MRB may be configured or established as a DTCH-only MRB, with a PDCP entity 713 and an RLC entity 719 associated with DTCH. In DTCH-only mode, the RLC entity 718 associated with MTCH is either not configured or not activated/established.

RLC-based retransmission 720 enables retransmission processing at the RLC layer to enhance reliability. In an embodiment, the RLC-based MRB is configured as a split MRB with a PDCP entity and one RLC entity 721 associated with MTCH and DTCH. RLC based MRBs may be configured or established as MTCH-only MRBs, with one PDCP entity and one RLC entity 722 associated with MTCH. In MTCH-only mode, DTCH is either not configured or initiated/established. RLC based MRBs may be configured or established as DTCH-only MRBs, with one PDCP entity and one RLC entity 723 associated with DTCH. In DTCH-only mode, MTCH is either not configured or not enabled/established.

MAC-based retransmission 730 enables retransmission processing at the MAC layer to enhance reliability. In an embodiment, the MAC based MRB is configured as a split MRB with one PDCP entity, one RLC entity and one MAC entity 731 that maps MTCH to both MCH and DL-SCH. A MAC-based MRB can be configured or established as an MTCH-only MRB, with one PDCP entity, one RLC entity, and one MAC entity 732 that maps MTCH to MCH. In MTCH-only mode, DTCH is either not configured or initiated/established. A MAC based MRB can be configured or established as a DTCH-only MRB with one PDCP entity, one RLC entity and one MAC entity 733 that maps MTCH to DL-SCH. In DTCH-only mode, MTCH is either not configured or not enabled/established.

FIG. 8 is a schematic diagram of top-level design of MRB establishment, release and reconfiguration processes for different retransmission configurations according to an embodiment of the present invention. The UE monitors and detects one or more activation/establishment conditions 801 of the MRB configuration. In step 810, upon detection of one or more establishment conditions, the UE may establish an MRB for the active MBS and the UE protocol stack based on the configured MRB, wherein the MRB is associated with one or two channels including a multicast channel and/or a unicast channel Associated. The UE applies the MRB establishment procedure to start receiving the session of the multicast service. When one of the establishment conditions is satisfied, the UE establishes/adds the MRB. Establishment conditions include initializing the active MBS, entering the multicast service area, re-entering the multicast service area, being interested in receiving the indication of the active MBS, and receiving commands for establishing/adding MRBs (such as RRC reconfiguration messages).

The UE monitors and detects one or more release conditions 802 of the MRB configuration. In step 820, the UE releases the MRB when one or more release conditions are detected. The UE applies the MRB release procedure to stop receiving the session. When one of the release conditions is met, the UE releases/removes the MRB. The release conditions include: stopping the active MBS, leaving the multicast service area, stopping receiving the indication of the active MBS, losing interest in the multicast service, receiving a command to release the MRB, and a state transition of leaving from the UE connected state.

The UE monitors and detects one or more reconfiguration conditions 803 of the MRB configuration. In step 830, upon detection of one or more reconfiguration conditions, the UE reconfigures MRBs. The UE applies the MRB reconfiguration procedure to change the MRB type (e.g. split MRB, MTCH-only MRB, DTCH-only MRB), switch the transmission mode (i.e. PTM, PTP or PTM+PTP) for an ongoing session of the multicast service. When one of the reconfiguration conditions is met, the UE reconfigures/modifies MRBs. The reconfiguration conditions include performing a state transition to the UE connected state and receiving a command to modify/reconfigure the MRB.

FIG. 9 is an exemplary schematic diagram of MRB establishment processes for different retransmission configurations according to an embodiment of the present invention, including a process 910 based on PCDP, a process 920 based on RLC and a process 930 based on MAC. For the process 910 of obtaining reliability enhancement based on PDCP retransmission, in step 911, the UE establishes a PDCP entity for the MRB. The UE establishes split MRBs, MTCH-only MRBs or DTCH-only MRBs. In step 912, UE establishes RLC entity and configures MTCH logical channel for MRB. In step 913, the UE establishes an RLC entity and configures a DTCH logical channel for the MRB. Execute step 912 for only MTCH MRBs and split MRBs, and execute step 913 for only DTCH MRBs and split MRBs. The UE establishes two RLC entities and configures two logical channels for MRB, configures MTCH in step 915 and configures DTCH in step 916 . Execute step 915 for only MTCH MRB and split MRB, and execute step 916 for only DTCH MRB and split MRB. In step 917, the UE configures a MAC entity to map MTCH to MCH and/or map DTCH to DL-SCH.

For the RLC-based retransmission process 920, at step 921, the UE establishes a PDCP entity and a specific RLC entity for the MRB. The UE establishes split MRBs, MTCH-only MRBs or DTCH-only MRBs. In step 922, the UE establishes an RLC entity and configures a logical channel of MTCH or DTCH or both for MRB. At step 925, the MTCH is configured based on the MRB configuration. At step 926, the DTCH is configured based on the MRB configuration. Step 925 is performed for MTCH-only MRBs and split MRBs. Step 926 is performed for DTCH-only MRBs and split MRBs. In step 927, the UE configures a MAC entity to map MTCH to MCH and/or DTCH to DL-SCH.

For the MAC-based procedure 930, at step 931, the UE establishes a PDCP entity. In step 932, the UE establishes an RLC entity for the MRB. In step 933, the UE configures a MAC entity to map MTCH to MCH and DL-SCH.

FIG. 10 is an exemplary schematic diagram of MRB reconfiguration processes for different retransmission configurations according to an embodiment of the present invention, including a PDCP-based reconfiguration process 1010, an RLC-based reconfiguration process 1020, and a MAC-based reconfiguration process 1030. For the process 1010 of obtaining reliability enhancement based on PDCP retransmission, in step 1011, the UE reconfigures the PDCP entity for the MRB according to the configuration (such as pdcp-config). In step 1012, the UE performs RLC bearer addition/modification based on the configuration (such as RLC-BearerConfig). Correspondingly, the PDCP entity is reconfigured as one of the following three options: one RLC entity for MTCH, one RLC entity for DTCH, or two RLC entities for MTCH and DTCH respectively for MRB. For MRB reconfiguration, a change between three options is performed. If no logical channel with the given logical channel identity (logicalChannelIdentity) has been previously configured, the UE associates the logical channel with the PDCP entity identified by the servedRadioBearer. In step 1013, the UE configures a MAC entity for the logical channel according to the configuration (such as mac-LogicalChannelConfig).

For the RLC-based retransmission process 1020, in step 1021, the UE reconfigures the PDCP entity for the MRB according to the configuration (such as pdcp-config). In step 1022, the UE performs RLC entity reconfiguration based on the configuration (such as RLC-BearerConfig). Correspondingly, an RLC entity is associated with one or two logical channels, namely MTCH, DTCH or DTCH and MTCH. For RLC reconfiguration, a change between associations with MTCH, DTCH, and MTCH and DTCH is performed. In step 1023, the UE configures a MAC entity for the logical channel according to the configuration (such as mac-LogicalChannelConfig).

For the MAC-based retransmission process 1030, in step 1031, the UE reconfigures the PDCP entity for the MRB according to the configuration (such as pdcp-config). In step 1032, the UE performs RLC bearer addition/modification based on the configuration (such as RLC-BearerConfig). In step 1033, the UE configures a MAC entity for the logical channel according to the configuration (such as mac-LogicalChannelConfig). Correspondingly, a MAC entity is associated with one or two transport channels, namely MCH, DL-SCH or MCH and DL-SCH.

FIG. 11 is an exemplary schematic diagram of MRB configuration release processes for different retransmission configurations according to an embodiment of the present invention, including a PDCP-based release process 1110, an RLC-based release process 1120, and a MAC-based release process 1130. For the process 1110 of obtaining reliability enhancement based on PDCP retransmission, at step 1111 , the UE releases the PDCP entity for the MRB. At step 1112, the UE releases one or both RLC entities and associated logical channels. In step 1113, the UE releases the MAC configuration of the MRB. For the process 1120 of obtaining reliability enhancement based on RLC retransmission, at step 1121, the UE releases the PDCP entity for the MRB. At step 1122, the UE releases the RLC entity and associated one or two logical channels. In step 1123, the UE releases the MAC configuration of the MRB. For the procedure 1130 for reliability enhancement based on MAC retransmission, at step 1131 , the UE releases the PDCP entity for the MRB. At step 1132, the UE releases the RLC entity and the associated logical channel, ie MTCH. In step 1133, the UE releases the MAC configuration of the MRB.

FIG. 12 is an exemplary flowchart of performing MRB reconfiguration during RRC state transition from idle/inactive to connected according to an embodiment of the present invention. In step 1201, the UE establishes an MRB in an idle/inactive state for a multicast service. In step 1202, the UE transitions to connected mode for unicast service. In step 1203, the UE sends a multicast interest indication to the network to inform which multicast service is ongoing or interested. In step 1204, in response to the interest indication, the UE receives an RRC reconfiguration message to reconfigure the MRB. The UE then performs MRB reconfiguration based on the RRC reconfiguration message.

FIG. 13 is an exemplary flowchart of UE MRB configuration, establishment, reconfiguration and release procedures for reliable MBS according to an embodiment of the present invention. In step 1301, the UE configures MRBs for one or more MBSs in a wireless network, wherein the MRB configuration enables feedback to one or more MBSs. In step 1302, upon detection of one or more activation conditions, the UE establishes an MRB and UE protocol stack for an active MBS based on the MRB configuration, wherein the MRB is associated with one or two channels including a multicast channel and a unicast channel. In step 1303, the UE receives the data packet of the active MBS through the established MRB in the multicast service area including one or more serving cells. In step 1304, the UE reconfigures the MRB to change the type of the MRB when one or more reconfiguration conditions are detected. In step 1305, the UE releases the MRB upon detection of one or more release conditions.

In an embodiment, a storage medium (such as a computer-readable storage medium) stores a program, and when the above program is executed, the UE executes the embodiment of the present invention.

Although the present invention has been disclosed above with respect to preferred embodiments, it is not intended to limit the present invention. Various changes, modifications and combinations can be made to each feature in each embodiment without departing from the scope of protection of the present invention defined by the patent scope of the application.

100: wireless system 101-102: User Equipment 106-108: base station 109: 5G network entities 121-122: Xn interface 131-133: NG connection 151, 161: memory 152, 162: Processor 153, 163: Transceiver 154, 164: program 155: Control module 156, 165: Antenna 181, 401, 501, 601: SDAP layer 182, 402, 502, 602: PDCP layer 183, 403, 503, 603: RLC layer 184, 404, 504, 604: MAC layer 185: PHY layer 191:MRB configuration module 192:MRB control module 193:MRB receiving module 194:MRB release module 195:MRB reconfiguration module 197: RRC state controller 198:MBS controller 199: Protocol stack controller 201: Core unit 211:Central unit 221-223: Decentralized Units 231-233: Community 250, 260: embodiment 251: gNB lower layer 252: gNB upper layer 261: Protocol stacking 301-303: UE protocol stack 310, 320, 330: Examples 311, 321, 331, 701-703: MRB 312, 322, 332: PTM branches 313, 323, 333: PTP branches 411-433, 511-513, 611-613: QoS flow processing 421-423, 4212-4222, 521-522, 5212-5222, 621-623, 6212-6222: ROHC 424-426, 4242-4252, 524-525, 5242-5252, 624-626, 6242-6252: Security 431-436, 531-535, 631-635: Segmentation and ARQ 441-442, 541-542, 641: Scheduling and Prioritization 443-445, 543-545, 643-644: multiplexing 446-448, 546-548, 646-647: HARQ 481, 581, 681: QoS flow 482, 582, 682: RB 483, 583, 683: RLC channel 484, 584, 684: logical channel 485, 585, 685: transmission channel 490, 710, 910, 1010, 1110: based on PDCP 491, 591, 691, 711, 712, 713: PDCP entity 492-493, 592, 692, 714-715, 716-717, 718-719, 721-723: RLC entities 494, 594, 694, 731-733: MAC entity 495, 595, 695: PHY entity 590, 720, 920, 1020, 1120: based on RLC 690, 730, 930, 1030, 1130: based on MAC 801-803: Conditions 810-830, 911-917, 921-927, 931-933, 1011-1013, 1021-1023, 1031-1033, 1011-1113, 1121-1123, 1131-1133, 1201-1204, 1301-1305: Procedure

A more complete understanding of this application can be had by reading the ensuing detailed description and examples with reference to the accompanying drawings, in which: FIG. 1 is a schematic system diagram of a wireless communication network supporting reliable multicast transmission for multicast services according to an embodiment of the present invention. FIG. 2 is a schematic diagram of an exemplary NR wireless system with a centralized upper layer of an NR radio interface stack according to an embodiment of the present invention. FIG. 3 is an exemplary diagram of different MRB configurations for supporting reliable MBS according to an embodiment of the present invention. FIG. 4 is a schematic diagram of a protocol stack with MRB configuration based on PDCP retransmission according to an embodiment of the present invention. FIG. 5 is a schematic diagram of a protocol stack with RLC retransmission-based MRB configuration according to an embodiment of the present invention. FIG. 6 is a schematic diagram of a protocol stack with MAC retransmission-based MRB configuration according to an embodiment of the present invention. FIG. 7 is a schematic diagram of a table for establishing MRB configurations for different retransmission configurations according to an embodiment of the present invention. FIG. 8 is a schematic diagram of top-level design of MRB establishment, release and reconfiguration processes for different retransmission configurations according to an embodiment of the present invention. FIG. 9 is an exemplary diagram of an MRB establishment process for different retransmission configurations according to an embodiment of the present invention. FIG. 10 is an exemplary diagram of an MRB reconfiguration process for different retransmission configurations according to an embodiment of the present invention. FIG. 11 is an exemplary schematic diagram of the MRB configuration release process for different retransmission configurations according to an embodiment of the present invention. FIG. 12 is an exemplary flowchart of performing MRB reconfiguration during RRC state transition from idle/inactive to connected according to an embodiment of the present invention. FIG. 13 is an exemplary flowchart of UE MRB configuration, establishment, reconfiguration and release procedures for reliable MBS according to an embodiment of the present invention.

1301-1305: steps

Claims (9)

A method for multicast broadcast service, comprising: configuring a multicast radio bearer MRB for one or more multicast broadcast service MBS in a wireless network by a user equipment, wherein an MRB configuration is enabled for the Feedback of one or more MBSs, wherein the MRB is configured to enable feedback to the active MBS based on PDCP retransmission, and wherein the user equipment agrees that the stack includes an MRB PDCP entity; upon detection of one or more When a condition is activated, based on the MRB configuration, the MRB and a user equipment protocol stack are established for the active MBS, wherein the MRB is associated with one or two channels including a multicast channel and a unicast channel; receiving data packets of the active MBS via the established MRB in a multicast service area of one or more serving cells; reconfiguring the MRB when one or more reconfiguration conditions are detected, to change the MRB A type of , wherein reconfiguring the MRB includes reconfiguring the MRB PDCP entity, and updating one or two corresponding RLC entities for the MRB; and releasing the MRB when one or more release conditions are detected . The method for multicast broadcast service according to claim 1, wherein the one or more start conditions include: initializing the active MBS, entering the multicast service area, re-entering the multicast service area . Interested in receiving an indication of the active MBS, and receiving an order to establish the MRB. The method for multicast broadcast service according to claim 1, wherein the one or more release conditions include: stopping the active MBS, leaving the multicast service area, losing interest in the multicast service, Stop receiving an indication of the active MBS, receive a command to release the MRB, and perform a state transition to leave the connected state of the UE. The method for multicast broadcast service as recited in claim 1, wherein the MRB is configured to enable feedback for the active MBS based on a Packet Data Convergence Protocol (PDCP) retransmission, and wherein the user equipment protocol stack Including an MRB PDCP entity. The method for multicast broadcast service according to claim 4, wherein the MRB is established together with a multicast channel and a unicast channel, and the user equipment protocol stack further includes two radio link control RLC entities , a multicast data packet for the multicast channel, and a unicast data packet for the unicast channel. The method for multicast broadcast service as recited in claim 4, wherein the MRB is established through a single channel selected from a multicast channel and a unicast channel, and wherein the UE protocol stack further includes an RLC entity. The method for multicast broadcast service according to claim 4, wherein releasing the MRB includes: releasing the MRB PDCP entity for the MRB; releasing one or two corresponding RLC entities for the MRB; and Release one or two logical channels associated for the MRB. The method for multicast broadcast service as claimed in claim 1, wherein the reconfiguration condition includes performing a UE state transition to UE connected state, and receiving a command to modify the MRB. A user equipment, comprising: a transceiver for sending and receiving wireless signals in a wireless network; a multicast radio bearer MRB configuration module for configuring an MRB in the wireless network for a or a plurality of multicast broadcast service MBSs, wherein the MRB is configured to enable feedback to the one or more MBSs, wherein the MRB is configured to enable feedback to the active MBSs based on PDCP retransmissions, and wherein the user The device protocol stack includes an MRB PDCP entity; An MRB control module, configured to establish the MRB and a user equipment protocol stack for an active MBS based on the MRB configuration when one or more activation conditions are detected, wherein the MRB includes a multicast channel and One or two channels of a unicast channel are associated; an MRB receiving module is used to receive the data packet of the active MBS through the established MRB in a multicast service area including one or more service cells ; An MRB reconfiguration module, used to reconfigure the MRB when one or more reconfiguration conditions are detected, so as to change a type of the MRB, wherein reconfiguring the MRB includes reconfiguring the MRB PDCP entity, and update one or two corresponding RLC entities for the MRB; and an MRB release module, release the MRB when one or more release conditions are detected.

Images