Multicast broadcast service reception with duplicate data packets

Abstract

The present invention provides an apparatus and method for MBS reception with duplicate data packets. In an example, a UE establishes a protocol stack with a PTM branch and a PTP branch, receives duplicate data packets from the PTM branch and the PTP branch, and processes the duplicate data packets from the PTM and PTP branches at a duplicate protocol layer. The MBS data packets are duplicated at a corresponding duplicate protocol layer of a network node. The UE duplicate protocol layer may be a PDCP layer, an RLC layer, or a PHY layer. When the RLC SN is different in PTM, the RLC layer includes a PTM RLC entity and a PTP RLC entity. The UE duplicate protocol layer merges received data packets and / or discards duplicate data packets from the PTM branch and the PTP branch. By utilizing the present invention, MBS transmission and reception can be performed reliably.

Description

[0001] Cross-references

[0002] This application is filed under 35 USC §111(a), and is based on and claims priority under 35 USC §120 and §365(c) to international application No. PCT / CN2020 / 103241, filed on July 21, 2020, with the invention title “Methods and apparatus of Multicast and Broadcast Service Reception,” and the above application is incorporated by reference. Technical Field

[0003] The present invention relates to wireless communications, and more particularly to multicast broadcast service (MBS) reception with duplicated data packets. Background Art

[0004] With the exponential growth of wireless data services, content delivery to large mobile user groups has developed rapidly. The initial wireless multicast / broadcast services included streaming services such as mobile TV and IPTV. With the growing demand for content delivery to large groups, the latest application developments for mobile multicast services require highly robust and critical communication services, such as group communications in disaster situations, and the necessity of multicast services related to public safety networks. Early 3GPP defined enhanced multimedia broadcast multicast service (eMBMS) in the long term evolution (LTE) standard. Single-cell point to multipoint (SC-PTM) service and multicast-broadcast single-frequency network (MBSFN) are also defined. 5G MBS is defined based on the unicast 5G core (5Gcore, 5GC) architecture. Various applications may rely on communications over multicast transmissions, 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 broadcast transmissions to ensure the reception quality on the UE side. The reception and transmission of MBS in the NR system requires higher reliability. In order to ensure higher reliability, feedback on the reception of MBS data packets is required to help the network perform necessary retransmissions. In addition, the traditional PTM / multicast radio bearer (RB) transmission and reception method cannot meet the MBS requirements for many service reliability requirements.

[0005] Improvements and enhancements are needed to increase the reliability of MBS transmission and reception. Summary of the invention

[0006] The present invention provides an apparatus and method for MBS reception with duplicate data packets. In an example, a UE establishes a protocol stack with a PTM branch and a PTP branch for a configured MBS. The UE receives duplicate data packets from the PTM branch and the PTP branch at the same time, and processes the duplicate data packets from the PTM and PTP branches at the duplication protocol layer. The MBS data packets are duplicated at the corresponding duplication protocol layer of the network node. In one embodiment, the UE duplication protocol layer is a PDCP layer, and the PDCP SNs of the PTM branch and the PTP branch are unified. In another embodiment, the UE duplication protocol layer is an RLC layer. When the RLC SNs in the PTM and PTP branches are different, the RLC layer includes two RLC entities, one for the PTM branch and one for the PTP branch. In another embodiment, when the RLC SNs from the PTM branch and the PTP branch are aligned, the RLC layer includes one RLC entity. In yet another embodiment, the UE duplication layer is a PHY layer, and both the PTM branch and the PTP branch are received from HARQ. The UE monitors the G-RNTI of the PTM branch and the C-RNTI of the PTP branch. The UE duplicate protocol layer combines the data packets received from the PTM branch and the PTP branch, and / or discards the duplicate data packets received from the PTM branch and the PTP branch.

[0007] In another exemplary embodiment, the base station establishes a network protocol stack having a PTM branch and one or more PTP branches for one or more subscribed UEs for DL ​​data packets of the configured MBS. The base station transmits duplicate data packets for the MBS on the PTM branch and the PTP branch simultaneously, wherein the data packets for the MBS are duplicated at the duplication protocol layer. In one embodiment, the duplication layer is a PHY layer with HARQ, an RLC layer, or a PDCP layer.

[0008] The above is not intended to define the present invention. The present invention is defined by the claims.

[0009] By utilizing the present invention, MBS transmission and reception can be performed reliably. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The accompanying drawings illustrate embodiments of the present invention, wherein like numerals indicate like components.

[0011] Figure 1 is a system diagram of an exemplary NR wireless network supporting MBS transmission and reception with duplicate data packets in the wireless network.

[0012] Figure 2 is a diagram of an exemplary NR wireless system with a centralized upper layer of an NR radio interface stack and a UE stack supporting multicast and unicast protocols.

[0013] Figure 3is an exemplary schematic diagram of different transmission modes, wherein the PTM branch and the PTP branch are used for transmission and reception of MBS data packets.

[0014] Figure 4 is an exemplary schematic diagram of duplicate HARQ reception through PTM and PTP branches.

[0015] Figure 5 is an exemplary schematic diagram of duplicate RLC reception through PTM and PTP branches.

[0016] Figure 6 is an exemplary schematic diagram of duplicate PDCP reception via PTM and PTP branches.

[0017] Figure 7 is an exemplary schematic diagram of the top-level process of different MBS mode switching processes in MBS transmission and reception.

[0018] Figure 8 is an exemplary flow chart of UE MBS reception with duplicate data packets.

[0019] Fig. 9 is an exemplary flow chart of a base station MBS transmission with duplicate data packets. DETAILED DESCRIPTION

[0020] Reference will now be made in detail to some embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

[0021] The present application provides methods, devices, processing systems and computer-readable media for NR (new radio access technology or 5G technology) or other radio access technologies. NR can support various wireless communication services, such as enhanced mobile broadband for wide bandwidth, millimeter waves for high carrier frequencies, large-scale machine type communications for non-backward compatible MTC technologies, and / or mission-critical ultra-reliable low-latency communications. These services may have latency and reliability requirements. These services may also have different transmission time intervals (TTIs) to meet their respective quality of service (QoS) requirements. In addition, these services can coexist in the same subframe.

[0022] Figure 11 is a system diagram of an exemplary NR wireless network supporting MBS transmission and reception with replicated data packets in a wireless network. A wireless system 100 (e.g., an NR wireless system) includes one or more fixed infrastructure units forming a network distributed over a geographic area. These infrastructure units may also be referred to as access points, access terminals, base stations, node Bs, evolved node Bs (eNode-Bs), next generation node Bs (gNBs), or other terms used in the art. The network may be a homogeneous network or a heterogeneous network and may be deployed using the same or different frequencies. gNB 101 and gNB 102 are base stations in the NR network, and their service areas may or may not overlap with each other. A backhaul connection such as 136 connects non-co-located receiving infrastructure units such as gNB 101 and 102. These backhaul connections may be ideal or non-ideal. gNB 101 is connected to gNB 102 via an Xn interface. Base stations such as gNB 101 and gNB 102 are connected to the 5GC network 103 through network interfaces, such as the N2 interface for the control plane and the N3 interface for the user plane.

[0023] NR wireless network 100 also includes multiple communication devices or mobile stations, such as user equipment (UE) 111, 112, 113, 114, 116, 117, 118, 121 and 122. UE may also be referred to as a mobile station, mobile terminal, mobile phone, smart phone, wearable device, IoT device, tablet computer, laptop computer or other terms used in the art. A mobile device may establish one or more unicast connections with one or more base stations. For example, UE 115 has a unicast connection 133 with gNB 101. Similarly, UE 121 is connected to gNB 102 via unicast connection 132.

[0024] In one example, one or more radio bearers are established for one or more multicast sessions / services. gNB101 and gNB 102 provide multicast service 1. UEs 111, 112, and 113 receive the multicast service from gNB 101. UEs 121 and 122 receive the multicast service from gNB 102. gNB 101 provides multicast service 2 to a UE group of UEs 116, 117, and 118. Multicast service 1 and multicast service 2 are transmitted in multicast mode via multicast radio bearers (MRBs) configured in the NR wireless network. The receiving UEs receive data packets of the multicast service via the corresponding configured MRBs. UE 111 receives multicast service 1 from gNB 101. gNB 102 also provides multicast service 1. In one example, unicast RBs associated with the multicast RBs are configured for reliable MBS. UE 121 is configured with multicast service 1. UE 121 is configured with multicast RBs and unicast RB 132. Unicast RB 132 receives MBS data packets together with multicast RBs. Unicast RB 132 is used to provide reliable MBS for UE 121. Similarly, UE 111, 112 and 113 receive multicast service 1 through corresponding multicast RBs and / or unicast RBs. For reliability, each UE receiving MBS is also configured with at least one corresponding unicast RB. Similarly, for multicast service 2, UE 116, 117 and 118 receive multicast service 2 through corresponding multicast RBs and / or unicast RBs. For reliability, each UE receiving MBS is also configured with at least one corresponding unicast RB. In one scenario, the multicast service is configured with a unicast radio bearer. Multicast service 3 is transmitted to UE 113 and UE 114 through unicast radio links 131 and 134, respectively. In one embodiment, upon detection of a predefined event, the MBS delivered via a unicast bearer through a point-to-point (PTP) protocol stack is switched to a point-to-multipoint (PTM) branch configured for the UE. The gNB switches the service mode from unicast to multicast using the PTM branch upon detection of one or more triggering events.

[0025] Figure 1A simplified block diagram of a base station and a mobile device / UE for MBS transmission and reception with replicated data packets is further shown. The gNB 102 has an antenna 156 that sends and receives radio signals. An RF transceiver circuit 153 coupled to the antenna receives an RF signal from the antenna 156, converts the RF signal to a baseband signal, and sends the baseband signal 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 signal and calls different functional modules to perform functional features in the gNB 102. The memory 151 stores program instructions and data 154 to control the operation of the gNB 102. The gNB 102 also includes a set of control modules 155 for performing functional tasks to communicate with the mobile station.

[0026] Figure 1 A simplified block diagram of a UE (such as UE 111) is also shown. The UE has an antenna 165 for sending and receiving radio signals. An RF transceiver circuit 163 coupled to the antenna receives an RF signal from the antenna 165, converts the RF signal into a baseband signal, and sends the baseband signal to the processor 162. In one embodiment, the RF transceiver may include two RF modules (not shown). The first RF module is used for high frequency (HF) transmission and reception; the other RF module is different from the HF transceiver and is used for transmission and reception in different frequency bands. The RF transceiver 163 also converts the baseband signal received from the processor 162 into an RF signal and sends it to the antenna 165. The processor 162 processes the received baseband signal and calls different functional modules to perform functional features in the UE 111. The memory 161 stores program instructions and data 164 to control the operation of the UE 111. Antenna 165 sends uplink transmissions to antenna 156 of gNB 102 and receives downlink (DL) transmissions from antenna 156 of gNB 102.

[0027] The UE also includes a set of control modules for performing functional tasks. These functional modules can be implemented by circuits, software, firmware or a combination of the above. The MBS configuration module 191 configures the MBS between the network nodes in the wireless network. The protocol module 192 establishes a UE protocol stack including a PTM branch and a PTP branch for DL ​​data packets of the MBS. The MBS receiving module 193 receives duplicate data packets of the MBS from the PTM branch and the PTP branch at the same time. The replication module 194 processes the duplicate data packets received from the PTM branch and the PTP branch at the replication protocol layer, wherein the data packets of the MBS are replicated at the corresponding replication protocol layer at the network node.

[0028] Figure 22 is a schematic diagram of an exemplary NR wireless system with a centralized upper layer of an NR radio interface stack and a UE stack supporting multicast and unicast protocols. There may be different protocol partitioning options between the central unit (CU) and distributed unit (DU) of a gNB node. The functional partitioning between the CU and DU of a gNB node may depend on the transport layer. Since the higher protocol layers have lower performance requirements on the transport layer in terms of bandwidth, delay, synchronization, and jitter, low-performance transmission between the gNB CU and DU can enable the high protocol layers of the NR radio stack to be supported in the central unit. In one embodiment, the service data adaptation protocol (SDAP) and packet data convergence protocol (PDCP) layers are located in the CU, while the RLC, media access control (MAC) and physical (PHY) layers are located in the DU. The core unit 201 is connected to the central unit 211 with the gNB upper layer 252. In one embodiment 250, the gNB upper layer 252 includes a PDCP layer and an optional SDAP layer. The central unit 211 is connected to the distributed units 221, 222, and 223, where 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, the gNB lower layer 251 includes PHY, MAC, and RLC layers. In another embodiment 260, each gNB has a protocol stack 261 including SDAP, PDCP, RLC, MAC, and PHY layers.

[0029] There are two delivery methods for transmitting MBS data packet streams over the air. The PTM delivery method refers to a radio area network (RAN) node delivering a single copy of an MBS data packet to a group of UEs over the air. The PTP delivery method refers to a RAN node delivering a separate copy of an MBS data packet to a single UE over the air. RAN nodes (i.e., gNBs or base stations) can use PTM, PTP, or a combination of PTP / PTM modes to deliver MBS data for a specific MBS service to interested UEs within a cell. The simultaneous PTP / PTM delivery modes are supported to meet different treatments of UEs for MBS service reception, such as different radio resource utilization schemes, or different QoS requirements. In addition, considering the need to support reliable multicast transmission, the accompanying / associated PTP transmission branch can be used to perform UE-specific retransmissions. Then from the perspective of the RAN node, there are four transmission modes for transmitting MBS data over the air interface: PTM-only transmission, PTP-only transmission, PTM and PTP (where PTP is used for initial transmission), and PTM and PTP (where PTP is used only for retransmission).

[0030] Figure 3 is an exemplary schematic diagram of different transmission modes, where PTM branches and PTP branches are used for transmission and reception of MBS data packets. The RAN node / network node configures MBS for one or more subscribed UEs in the wireless network. Each subscribed UE configures MBS with the network node. When the RAN node configures PTM branches and PTP branches for MBS data transmission for a specific MBS session, some UEs may receive only PTM branches, some UEs may receive only PTP branches, and some UEs may receive both PTM branches and PTP branches.

[0031] Corresponding to the transmission mode adopted by the RAN node, there are also different options to model the reception behavior from the perspective of UE reception. The four transmission modes include PTM-only mode 301, PTP-only mode 302, PTM-PTP mode 303, and PTM-retransmission-only-PTP mode 304. For PTM-only mode 301, the UE only receives the PTM branch regardless of any other PTP branches established by the network for other UEs. From the perspective of the UE, reliable reception is not expected in this case. This option requires the RAN node to establish a PTM branch for the transmission of a specific MBS session. For PTP-only mode 302, the UE only receives the PTP branch regardless of the ongoing PTM branches established by the network for other UEs. From the perspective of the UE, reliable reception can be expected if necessary. This option requires the RAN node to establish a UE-specific PTP branch for the transmission of a specific MBS session. For PTM-PTP mode 303, the UE receives the initial transmission of MBS data from the PTM branch and the PTP branch. The RAN node establishes a PTM branch and a UE-specific PTP branch for the UE. The RAN node transmits data to the PTM branch and the UE-specific PTP branch in a duplicated manner. During MBS reception, the UE merges the duplicated MBS data packets received from the PTM branch and the PTP branch, and discards the duplicated data if any. For the PTM-retransmission-only-PTP mode 304, the UE receives the initial transmission of the MBS data from the PTM branch and receives the retransmission of the MBS data from the PTP branch. The RAN node establishes the PTM branch and the UE-specific PTP branch for the UE. The PTP branch is only used for data retransmission based on UE-specific uplink feedback. During MBS reception, the UE merges the data received from the two branches.

[0032] Different configurations / alternatives may be implemented for each MBS mode based on the protocol layer handling uplink feedback, duplicating reception or receiving retransmission data on a PTM branch and / or a PTP branch.

[0033] Alt-1A 311: PTM reception only without providing UL feedback, which is traditional PTM reception.

[0034] Alt-1B 312: PTM-only reception with HARQ layer uplink feedback.

[0035] Alt-2A 321: PTP reception only, no UL feedback is provided, this is traditional PTP reception.

[0036] Alt-2B 322: PTP-only reception with HARQ layer uplink feedback, which is legacy PTP reception.

[0037] Alt-2C 323: PTP-only reception with RLC layer uplink feedback, which is the legacy PTP reception.

[0038] Alt-2D 324: PTP-only reception with PDCP layer uplink feedback, which is legacy PTP reception.

[0039] Alt-3B 331: PTM / PTP reception, duplicate HARQ layer reception via the PTM / PTP branch.

[0040] Alt-3C 332: PTM / PTP reception, duplication of RLC layer reception via PTM / PTP tributary.

[0041] Alt-3D 333: PTM / PTP reception, which replicates the PDCP layer reception through the PTM / PTP branch.

[0042] Alt-4B 341: PTM / PTP reception with HARQ layer uplink feedback (reception of PTP branches for HARQ retransmissions).

[0043] Alt-4C 342: PTM / PTP reception with RLC layer uplink feedback (reception of PTP branches for RLC retransmission).

[0044] Alt-4D 343: PTM / PTP reception with PDCP layer uplink feedback (reception of PTP branches for PDCP retransmission).

[0045] For Alt-1A 311, the UE does not provide any feedback. This configuration is suitable for services such as broadcast applications. In one embodiment, the network performs a one-shot transmission. In another embodiment, the network performs blind retransmission in HARQ or L2. Following the general principle of PTM RB reception, it requires the UE to establish a single PDCP entity and RLC entity for DL ​​reception, and the RLC entity operates in receive-only mode. For Alt-1B 312, the UE needs to provide HARQ feedback based on the resources allocated by the RAN node. In one embodiment, the network uses HARQ feedback to determine the required retransmission. For PTP-only mode processes, including Alt-2A321, Alt-2B 322, Alt-2C 323 and Alt-2D 324, the UE is configured with a PTP branch for MBS. The UE uses unicast reception to receive MBS data packets. The network needs to establish an independent UE-specific PTP RB for the UE.

[0046] For PTM and PTP modes 303, three schemes 331, 333 and 332 are available. For Alt-3B 331, the UE receives the PTM branch and the PTP branch at the HARQ layer. In one embodiment of Alt-3B 331, from the HARQ point of view, the replication is at the PHY layer, and the details can be found in Figure 4 In another embodiment of Alt-3C 332, the replication is located at the RLC layer, for details, see Figure 5 In another embodiment of Alt-3D 333, the replication is located at the PDCP layer, for details, see Figure 6 .

[0047] For the PTM-retransmission-only-PTP mode 304, three schemes 341, 342 and 343 are available. In one embodiment of Alt-4B 341, the UE receives the PTM branch and the PTP branch from the HARQ perspective. In one embodiment, the UE monitors the PDCCH scrambled by the group radio network temporary identifier (G-RNTI) for PTM reception and monitors the PDCCH scrambled by the cell RNTI (C-RNTI) for PTP reception. The UE can only receive HARQ retransmissions of transmission blocks (TBs) from the PTP branch. The UE always receives different RV versions of the same TB from two branches. In one embodiment, HARQ combining is performed at the physical layer. The UE provides its uplink HARQ feedback to the network based on the HARQ combining result for a specific TB, and expects to receive HARQ retransmissions for the same TB from the PTP branch. At the RAN node side, the initial transmission of TBs for multicast data is performed on the PTM branch, while the retransmission of TBs occurs on the PTP branch. In one embodiment, the HARQ transmission is supported by different HARQ entities or different HARQ processes.

[0048] In another embodiment of Alt-4C 342, on the UE side, the UE performs PTP as well as PTM reception. The PTP branch is monitored only to receive retransmitted RLC data packets. The UE establishes a single / combined DRB and a single PDCP entity to receive the PTM branch and the PTP branch. The UE can establish a single RLC entity to receive both branches. The UE monitors two independent logical channels (LCH) with different RNTIs, one for PTM data and the other for PTP data. The UE assembles data packets from two independent LCHs in the RLC, assuming that the sequence numbers (SN) are aligned because the sequence numbers (SN) should be allocated by a single RLC SN allocation function block on the network side. In the uplink, when a polling request for multicast transmission is received, the UE provides uplink feedback (i.e., RLC status report) to the network. The network side supports independent RLC functions for each UE. It should be noted that the PTP RLC function is only a part of the RLC entity function because there is no SN allocation function. The PDCP packets are transferred to the common RLC SN allocation function block of the RLC layer. The PTM RLC entity operates for initial PTM transmissions. Any transmission in PTP (or unicast mode) is for PTP retransmissions. In one embodiment, each UE-specific RLC AM entity has one or more retransmission buffers.

[0049] In another embodiment of Alt-4D 343, on the UE side, the UE performs PTP as well as PTM reception. The UE establishes a single / combined DRB and a single PDCP entity to receive the PTM branch and the PTP branch. In one embodiment, the UE establishes two RLC entities to receive the two branches, both of which operate in RLC UM mode. The UE monitors two independent LCHs (one for PTM data and the other for PTP data) through different RNTIs. The UE assembles data packets from the two independent LCHs in PDCP. Because the SN should be allocated by a single PDCP SN allocation functional block on the network side, the UE assumes that the SNs are aligned. In the uplink, the UE provides uplink feedback (i.e., PDCP status report) to the network. In one embodiment, when a polling request for multicast transmission is received, an uplink report is sent to the network. From the network side, the network side supports independent PDCP functions for each UE. The PTP PDCP function is only a part of the PDCP entity function because there is no SN allocation function. The SDAP packet is transmitted to the common PDCP SN allocation functional block of the PDCP layer. The PTM PDCP entity operates for initial PTM transmissions. Any transmission in PTP (or unicast mode) is for PTP retransmissions. In one embodiment, each UE-specific PDCP AM entity has one or more retransmission buffers.

[0050] Figure 4 4 is an exemplary schematic diagram of duplicate HARQ reception through PTM and PTP branches. UE 410 is configured with MBS. UE 410 is configured with a UE protocol stack including a PTM branch and a PTP branch for DL ​​data packets of MBS. The UE 410 protocol stack includes two PHY entities: PTM HARQ 411 and PTP HARQ 412. The UE 410 protocol stack also includes a MAC entity 413, an RLC entity 415 and a PDCP entity 417. UE 410 receives duplicate data packets for MBS from the PTM branch and the PTP branch at the same time, and processes the duplicate data packets received from the PTM branch and the PTP branch at a duplicate protocol layer (such as a PHY layer), wherein the data packets of MBS are duplicated at the corresponding duplicate protocol layer of the network node. The PDCP entity 417 sends the processed data packet 401 to the upper layer of UE 410. An exemplary network node gNB 430 transmits one or more multicast streams 403 for MBS to one or more UEs, such as UE 410. The MBS from gNB 430 is configured with PTM RBs and PTP RBs. The UE monitors the PDCCH scrambled by G-RNTI for PTM reception and monitors the PDCCH scrambled by C-RNTI for PTP reception. The UE may receive the same TB from two branches. The UE may receive the same or different RV versions of the same TB from two branches. The PHY layer performs HARQ combining through PHY entities 411 and 412. In one embodiment, the UE provides its uplink HARQ feedback to the network based on the HARQ combining result of a specific TB, expecting to receive HARQ retransmissions of the same TB. At the network node end, the multicast data packet is replicated on the PTM branch and the PTP branch at the HARQ layer through different HARQ entities or different HARQ processes, such as PTM HARQ of PHY 431 and PTM HARQ of PHY 432. The gNB 430 transmits the duplicated data packets of the MBS on the PTM branch and the PTP branch simultaneously, wherein the data packets of the MBS are duplicated at the duplication protocol layer, the PHY layer with HARQ entities 431 and 432. The network protocol stack also includes a MAC entity 433, an RLC (UM) entity 435, and a PDCP entity 437.

[0051] Figure 5 is an exemplary schematic diagram of duplicate RLC reception through PTM and PTP branches.

[0052] UE 510 is configured with MBS. UE 510 is configured with UE protocol stack, which can be used through PTM branch and

[0053] The PTP branch receives the DL data packet of the MBS. The UE 510 protocol stack includes a PHY entity 511, a MAC entity 513, two RLC entities (including a PTM RLC entity 515 and a PTP RLC entity 516), and a PDCP entity 517. The UE 510 receives the duplicate data packets of the MBS from the PTM branch and the PTP branch at the same time, and processes the duplicate data packets received from the PTM branch and the PTP branch at the duplication protocol layer (such as the RLC layer), wherein the data packets for the MBS are duplicated at the RLC layer of the network node. The PDCP entity 517 sends the processed data packet 501 to the upper layer of the UE 510.

[0054] The exemplary network node gNB 530 transmits one or more multicast streams 503 for MBS to one or more UEs, such as UE 510. The gNB 530 establishes a network protocol stack for DL ​​data packets of MBS, including a PTM branch and one or more PTP branches for one or more subscribing UEs, and transmits duplicate data packets for MBS on the PTM branch and the PTP branch simultaneously, wherein the data packets for MBS are duplicated at the duplication protocol layer, the RLC layer having RLC entities 535 and 536. The network protocol stack also includes a PHY entity 531, a MAC entity 533, and a PDCP entity 537.

[0055] In one embodiment, the RLC SN of the PTM branch is different from the RLC SN of the PTP branch. The UE protocol stack includes two RLC entities, one for the PTM branch 515 and one for the PTP branch 516. The PDCP layer 517 of the UE protocol stack discards the duplicated data packets. From the perspective of RLC in a single DRB, the UE receives the PTM branch and the PTP branch. In one embodiment, the UE receives the same PDCP packet from two transmission branches. The UE uses two RLC entities 515 and 516 to receive the two branches because the SN of the data packet is assigned by different RLC entities 535 and 536 on the network side. The RLC SN of the PTM branch is different from the RLC SN of the PTP branch of each subscribed UE. In one embodiment, the UE provides its independent uplink HARQ feedback to the network based on the reception of each transmission branch. There is no HARQ combining between the two branches. On the RAN node side, at the RLC layer, the multicast data packet is duplicated on the PTM branch and the PTP branch.

[0056] In another embodiment 520, the RLC SNs of the PTM branch and the PTP branch are aligned, and wherein the UE protocol stack includes an RLC entity to discard duplicate data packets. On the network side, the RLC SN allocation functions of the PTM branch and the PTP branch are combined. The RLC SNs of the PTM branch and the PTP branch of each subscribed UE are aligned. The RLC data packets transmitted through the PTM branch and the PTP branch share a consistent RLC SN. The alternative UE 520 protocol stack includes a PHY entity 521, a MAC entity 523, a combined RLC entity 525 for duplicate data packets, and a PDCP entity 527. The UE uses a single RLC entity 525 to receive the PTM branch and the PTP branch, and discards redundant RLC data packets based on checking the RLC SN of the data packets.

[0057] Figure 6 6 is an exemplary schematic diagram of duplicate PDCP reception through PTM and PTP branches. UE 610 is configured with MBS. UE 610 is configured with a UE protocol stack including a PTM branch and a PTP branch for DL ​​data packets of MBS. The UE 610 protocol stack includes a PHY entity 611, a MAC entity 613, two RLC entities for duplicate data (PTM RLC entity 615 and PTP RLC entity 616), and a PDCP entity 617. UE 610 receives duplicate data packets of MBS from the PTM branch and the PTP branch at the same time, and processes the duplicate data packets received from the PTM branch and the PTP branch at a duplicate protocol layer (such as a PDCP layer), wherein the data packets for MBS are duplicated at the PDCP layer of the network node. The PDCP entity 617 sends the processed data packet 601 to the upper layer of UE 610.

[0058] The exemplary network node gNB 630 transmits one or more multicast streams 603 for MBS to one or more UEs, such as UE 610. The gNB 630 establishes a network protocol stack for DL ​​data packets of MBS, including a PTM branch and one or more PTP branches. The data packets of MBS are replicated at the replication protocol layer, the PDCP layer. The PDCP layer includes a PDCP SN allocation functional entity 637, which is used to allocate PDCP SNs to PTM PDCP entity 638 and PTP PDCP entity 639. The RLC layer includes a PTM RLC functional entity 635 and a PTP RLC functional entity 636. The network protocol stack also includes a PHY entity 631 and a MAC entity 633.

[0059] At the PDCP layer, multicast data packets are replicated on the PTM branch and the PTP branch. The UE performs PTP and PTM reception together. From the UE reception perspective, the UE uses two RLC entities (RLC entity 615 for PTM branch and RLC entity 616 for PTP branch) to receive data from PTM and PTP branches. The network side has a unified SN allocation 637 for PDCP packets. The UE PDCP entity combines the data packets received from the PTM branch and the PTP branch based on the unified PDCP SN. At the RAN node side, at the PDCP layer, multicast data packets are replicated on the PTM branch and the PTP branch.

[0060] In another example, based on the UE reception selection, the UE reception option can be switched during MBS reception. In one embodiment, the decision to switch is made by the network. From the UE reception perspective, there are different cases for PTM / PTP switching, each of which requires different processing to achieve service continuity during the UE's PTM / PTP switching.

[0061] Figure 7 is an exemplary schematic diagram of the top-level process of different MBS mode switching processes in MBS transmission and reception. Figure 3 As discussed in , there are four MBS transmission modes: PTM-only 301, PTP-only 302, PTM-PTM 303, and PTM-retransmission-only-PTP mode 304. In an example, the network monitors one or more triggering events and initiates the mode switching. In the first scenario 710, the MBS transmission mode is switched from PTM-only to PTP-only. During the switching process, the data packets transmitted by the PTP branch need to be consistent with the data packets transmitted by the previous PTM branch to ensure service continuity. Specifically, if the PTM / PTP switching is implemented on HARQ, the next multicast TB from the upper layer needs to be delivered to the PTP HARQ entity, and the UE needs to monitor the C-RNTI scrambled PDCCH to receive the PTP branch. If the PTM / PTP switching is implemented on L2, the next L2 data packet transmitted to the UE via the PTP branch needs to inherit the SN from the PTM branch. In order to maintain service continuity, the UE expects to receive the data packets that were not successfully received (from the previous branch) after switching to the new branch.

[0062] In the second scenario 720, the MBS transmission mode is switched from PTP-only to PTM-only. During the switching process, the data packets transmitted by the PTM branch need to be consistent with the data packets transmitted by the previous PTP branch to ensure service continuity. Specifically, if PTM / PTP switching is implemented in HARQ, the next multicast TB from the upper layer needs to be delivered to the PTM HARQ entity, and the UE needs to monitor the G-RNTI-scrambled PDCCH to receive the PTM branch. If PTM / PTP switching is implemented in L2, the next L2 data packet transmitted to the UE via the PTM branch may or may not match the SN of the PTP branch. In order to maintain service continuity, the UE may receive data packets that were not successfully received after switching to the PTM branch.

[0063] In the third scenario 730, the MBS transmission mode is switched from the PTP-only mode to the PTM-PTP mode. During the switching, the UE needs to combine the data packets from the PTM branch and the PTP branch after the PTM / PTP switching. Since the PTP branch is still retained, this scenario can better maintain service continuity because the UE can receive the data packets that were not successfully received after switching from the PTP branch.

[0064] In the fourth scenario 740, the MBS transmission mode is switched from PTP-only to PTM-retransmission-only-PTP. During the switch, the UE is able to combine data packets from the PTM branch and the PTP branch (for retransmission) after the PTM / PTP switch. Since the PTP branch is still reserved for retransmission, this scenario can better maintain service continuity because the UE can receive data packets that were not successfully received after switching from the PTP branch. The data transmission consistency requirement is the same as 730.

[0065] In the fifth scenario 750, the MBS transmission mode is switched from PTM-PTP to PTP only. During the switching process, the PTP branch is still retained, which is more conducive to maintaining service continuity because the UE can receive unsuccessfully received data packets from the PTP branch after the switching. The data transmission consistency requirement is the same as 710.

[0066] In the sixth scenario 760, the MBS transmission mode is switched from PTM-retransmission-only-PTP to PTP only. During the switching process, the PTP branch is still retained, and the UE can receive the unsuccessfully received data packets from the PTP branch after the switching. The data transmission consistency requirement is the same as 710.

[0067] In one embodiment, the MBS transmission mode switching is a dynamic switching determined by the network based on one or more predefined triggering events. In one embodiment, the dynamic mode switching is handled by HARQ. In another embodiment, the dynamic mode switching is handled by the RLC layer. In yet another embodiment, the dynamic mode switching is handled by the PDCP layer. In the first embodiment, the dynamic mode switching is handled by HARQ. For example, for the switch from PTM-only to PTP-only based on scenario 710, a UE-specific PTP transmission branch can be established through a UE-specific HARQ entity. If there is no valid PTM transmission branch, the multicast TB will be transferred to PTP HARQ. In this case, if multiple UEs receive their specific PTP branches (which may include a PTM HARQ entity providing services to other UEs in PTM mode), the multicast TB is transmitted in a duplicate manner on multiple HARQ entities. If the UE does not correctly receive the previous multicast RB through the PTM mode before switching, the UE is at risk of missing the TB when switching to the PTP branch. The performance of service continuity during dynamic handover is subject to specific HARQ operations, such as HARQ retransmissions based on HARQ feedback during this period, which can be coordinated with RAN1 for further evaluation.

[0068] In a second embodiment, the dynamic mode switching is handled by the RLC layer. During the switching, the UE and the network use uplink feedback based on the RLC layer. For example, specifically to 710, a UE-specific PTP transmission branch can be established as an RLC transmission branch. During the switching from PTM-only to PTP-only, the PTM RLC function at the RAN node can be simply disabled. The RLC SN allocation function transmits new data packets to each UE-specific RLC function that has been established. From the UE's perspective, the protocol stack for data reception is retained, but there is no need to monitor the PTM branch. The RAN node needs to notify the UE of the above switching to perform corresponding adaptation from the UE side. In one scenario, after switching from PTM-only to PTP-only, the RAN node reserves multicast RBs to continue to support PTM transmission to other UEs. For the RAN node and the UE, the same PDCP entity is used after the switching. In another exemplary example of 760, the PTP branch exists for L2-based retransmission before the switching. After the switching, the PTP branch is used for initial transmission. If any RLC data packets need to be retransmitted after the switch, the data packets are transmitted via the PTP branch after the transmission mode is switched.

[0069] In a third embodiment, dynamic mode switching is handled by the PDCP layer. During switching, the UE and the network use uplink feedback based on the PDCP layer. For example, specifically to 710, a UE-specific PTP transmission branch can be established as a PDCP transmission branch. During switching, the PTM PDCP function of the RAN node can be simply disabled. The common PDCP SN allocation function transmits new data packets to each established UE-specific PDCP function. From the UE's perspective, the protocol stack for data reception is retained, but there is no need to monitor the PTM branch. For the RAN node and the UE, since the PDCP SN allocation function is maintained, the operation of the PDCP after the mode switch is consistent. PDCP-based mode switching should support PDCP feedback to allow PDCP-based retransmission after mode switching.

[0070] Figure 8 is an exemplary flow chart of UE MBS reception with duplicate data packets. In step 801, the UE configures MBS with a network node in a wireless network. In step 802, the UE establishes a UE protocol stack including a PTM branch and a PTP branch for DL ​​data packets of the MBS. In step 803, the UE simultaneously receives duplicate data packets for the MBS from the PTM branch and the PTP branch. In step 804, the UE processes the duplicate data packets received from the PTM branch and the PTP branch at a duplicate protocol layer, wherein the data packets for the MBS are duplicated at the corresponding duplicate protocol layer at the network node.

[0071] Fig. 9 is an exemplary flow chart of a base station MBS transmission with duplicate data packets. In step 901, the base station configures MBS for one or more subscribing UEs in a wireless network. In step 902, the base station establishes a network protocol stack for DL ​​data packets of the MBS, including a PTM branch for one or more subscribing UEs and one or more PTPs. In step 903, the base station transmits duplicate data packets for the MBS on both the PTM branch and the PTP branch, wherein the data packets for the MBS are duplicated at the duplication protocol layer.

[0072] Although the present invention has been described in conjunction with specific embodiments for illustrative purposes, the present invention is not limited thereto. Therefore, various modifications, adaptations and combinations of the various features of the described embodiments may be implemented without departing from the scope of the present invention as described in the claims.

Claims

1. A method for receiving a multicast broadcast service with a replicated data packet, comprising: A multicast broadcast service MBS between a user equipment and a network node in a wireless network; Establishing a user equipment protocol stack including a point-to-multipoint PTM branch and a point-to-point PTP branch for downlink data packets of the MBS; receiving the duplicate data packets of the MBS from the PTM branch and the PTP branch simultaneously; as well as The replicated data packets received from the PTM branch and the PTP branch are processed at a replication protocol layer, wherein the data packets of the MBS are replicated at the corresponding replication protocol layer at the network node.

2. The method for receiving a multicast broadcast service with a duplicate data packet as claimed in claim 1, wherein: The duplicate protocol layer is a Packet Data Convergence Protocol (PDCP) layer of the user equipment protocol stack, and wherein a sequence number SN of a PDCP packet is unified in the PTM branch and the PTP branch.

3. The method for receiving a multicast broadcast service with a duplicate data packet as claimed in claim 2, wherein: The user equipment protocol stack includes two radio link control RLC entities, one for the PTM branch and one for the PTP branch.

4. The method for receiving a multicast broadcast service with a duplicate data packet as claimed in claim 1, wherein: The duplicate protocol layer is the RLC layer of the user equipment protocol stack.

5. The method for receiving a multicast broadcast service with a duplicate data packet as claimed in claim 4, wherein: The RLC SN of the PTM branch is different from the RLC SN of the PTP branch, and the user equipment protocol stack includes two RLC entities, one for the PTM branch and one for the PTP branch, and wherein a PDCP layer of the user equipment protocol stack discards the duplicated data packet.

6. The method for receiving a multicast broadcast service with duplicate data packets as claimed in claim 4, wherein: RLC SNs of the PTM branch and the PTP branch are aligned, and the user equipment protocol stack includes an RLC entity that discards duplicate data packets.

7. The method for receiving a multicast broadcast service with a duplicate data packet as claimed in claim 1, wherein: The duplicate protocol layer is a physical layer of the user equipment protocol stack, and wherein the PTM branch and the PTP branch are both received at a hybrid automatic repeat request layer.

8. The method for receiving a multicast broadcast service with duplicate data packets as claimed in claim 7, wherein: The user equipment monitors a group radio network temporary identifier for the PTM branch and a cell radio network temporary identifier for the PTP branch.

9. The method for receiving a multicast broadcast service with a duplicate data packet as claimed in claim 1, wherein: Processing the received duplicate data packets includes at least one of the following processes: the process includes combining data packets received from the PTM branch and the PTP branch, and discarding duplicate data packets from the PTM branch and the PTP branch.

10. A method for transmitting a multicast broadcast service with a replicated data packet, comprising: The base station configures a multicast broadcast service MBS for one or more subscribing user equipments in the wireless network; Establishing a network protocol stack for downlink data packets of the MBS, including a point-to-multipoint PTM branch and one or more point-to-point PTP branches for the one or more subscribing user equipments; as well as The duplicate data packets for the MBS are transmitted on the PTM branch and the PTP branch at the same time, wherein the data packets for the MBS are duplicated at a duplication protocol layer.

11. The method for transmitting a multicast broadcast service with a duplicate data packet as claimed in claim 10, wherein: The duplicate protocol layer is a Packet Data Convergence Protocol (PDCP) layer of the network protocol stack, and a sequence number (SN) of a PDCP packet is unified in the PTM branch and the PTP branch.

12. The method of transmitting a multicast broadcast service with duplicate data packets as claimed in claim 10, wherein: The duplicate protocol layer is a Radio Link Control, RLC, layer of the network protocol stack.

13. The method for transmitting a multicast broadcast service with duplicate data packets as claimed in claim 12, wherein: For each subscribing user equipment, the RLC SN of the PTM branch is different from the RLC SN of the PTP branch.

14. The method of transmitting a multicast broadcast service with duplicate data packets as claimed in claim 12, wherein: The RLC SNs of the PTM branch and the PTP branch of each subscribing user equipment are aligned.

15. The method of transmitting a multicast broadcast service with duplicate data packets as claimed in claim 10, wherein: The duplication protocol layer is a physical layer of the network protocol stack, and wherein a data packet for the MBS is duplicated on the PTM branch and the PTP branch at a hybrid automatic repeat request layer having different hybrid automatic repeat request entities.

16. A user equipment, comprising: transceivers, which are used to send and receive radio frequency signals in wireless networks; A multicast broadcast service MBS configuration module, used to configure the MBS between the network nodes in the wireless network; A protocol module, used to establish a user equipment protocol stack including a point-to-multipoint PTM branch and a point-to-point PTP branch, for downlink data packets of the MBS; An MBS receiving module, used for simultaneously receiving the duplicated data packets of the MBS from the PTM branch and the PTP branch; as well as The replication module is used for processing the replication data packets received from the PTM branch and the PTP branch at a replication protocol layer, wherein the data packets of the MBS are replicated at the corresponding replication protocol layer at the network node.

17. The user equipment according to claim 16, characterized in that The duplicate protocol layer is a Packet Data Convergence Protocol (PDCP) layer of the user equipment protocol stack, and wherein the sequence number SN of the PDCP packet is unified in the PTM branch and the PTP branch, and the user equipment protocol stack includes two Radio Link Control (RLC) entities, one for the PTM branch and one for the PTP branch.

18. The user equipment according to claim 16, characterized in that The duplicate protocol layer is the RLC layer of the user equipment protocol stack.

19. The user equipment according to claim 18, characterized in that When the RLC SN of the PTM branch is different from the RLC SN of the PTP branch, the user equipment protocol stack includes two RLC entities, one for the PTM branch and one for the PTP branch; when the RLC SNs of the PTM branch and the PTP branch are aligned, the user equipment protocol stack includes an RLC entity that discards duplicate data packets.

20. The user equipment of claim 16, wherein the duplicate protocol layer is a physical layer of a protocol stack of the user equipment, and wherein both the PTM branch and the PTP branch are received at a hybrid automatic repeat request layer.

21. A storage medium storing a program, wherein when the program is executed, the user equipment executes the steps of the method for receiving a multicast broadcast service with duplicate data packets according to any one of claims 1 to 9.

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