Methods, apparatus and media for operating point-to-multipoint radio bearers

Abstract

Embodiments of this disclosure provide a solution for operating a radio bearer. According to embodiments of this disclosure, a terminal device monitors multiple data packets transmitted from a network device on the radio bearer. If reception of at least one of the multiple data packets fails, the terminal device can discard the at least one data packet without requesting a retransmission. The network device determines whether a retransmission condition for the at least one data packet has not been met. If the retransmission condition has not been met, retransmission of the at least one data packet is skipped.

Description

Technical Field

[0001] Embodiments of this disclosure generally relate to the telecommunications field, and more particularly to methods, apparatus and media for operating point-to-multipoint (PTM) radio bearers. Background Technology

[0002] With the development of communication technology, several solutions have been proposed to provide efficient and reliable communication. For example, Multicast and Broadcast Services (MBS) have been proposed to enable efficient use of radio and network resources when sending audio and video content to a large group of end users. In MBS scenarios, both Point-to-Point (PTP) and Point-to-Template (PTM) modes are supported when the base station transmits MBS data packets in the downlink. PTP mode means using unicast to send packets in the downlink to a specific terminal device with a Cell Radio Network Temporary Identity (C-RNTI). PTM mode means using multicast to send packets in the downlink to a group of terminal devices sharing a Common Group Radio Network Temporary Identity (G-RNTI). Further research is needed on solutions to improve MBS performance. Summary of the Invention

[0003] Overall, the exemplary embodiments of this disclosure provide a solution for operating a PTM radio bearer.

[0004] In a first aspect, a method performed by a terminal device is provided. The method includes: monitoring a plurality of data packets received from a network device on a first radio bearer; determining that at least one of the plurality of data packets has failed to be received; determining whether a retransmission condition for the at least one data packet has not been met; and discarding the at least one data packet without requesting a retransmission based on the determination that the retransmission condition has not been met.

[0005] In a second aspect, a method performed by a network device is provided. The method includes transmitting a plurality of data packets to a terminal device over a first radio bearer; determining whether a retransmission condition for at least one of the plurality of data packets has not been met; and, based on the determination that the retransmission condition has not been met, causing retransmission of at least one data packet to be skipped.

[0006] In a third aspect, an apparatus is provided. The apparatus includes a processor; and a memory coupled to the processor and storing instructions thereon, which, when executed by the processor, cause the apparatus to perform the method according to the first aspect.

[0007] In a fourth aspect, an apparatus is provided. The apparatus includes a processor; and a memory coupled to the processor and storing instructions thereon, which, when executed by the processor, cause the apparatus to perform the method according to the second aspect.

[0008] In a fifth aspect, a computer-readable medium is provided having instructions stored thereon, which, when executed on at least one processor, cause at least one processor to perform the method according to the first aspect.

[0009] In a sixth aspect, a computer-readable medium is provided having instructions stored thereon, which, when executed on at least one processor, cause at least one processor to perform the method according to the second aspect.

[0010] Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0011] The above and other objects, features and advantages of this disclosure will become more apparent from the more detailed description of some exemplary embodiments of this disclosure in the accompanying drawings, in which:

[0012] Figure 1 The diagram illustrates the radio access network (RAN) architecture of a central unit-distributed unit (CU-DU) separation system based on conventional technology.

[0013] Figure 2 The illustration shows a block diagram of a communication environment in which embodiments of the present disclosure can be implemented;

[0014] Figure 3 The diagram illustrates an example process for operating a radio bearer according to some embodiments of the present disclosure;

[0015] Figure 4 The diagram illustrates an example process for operating a radio bearer according to some embodiments of the present disclosure;

[0016] Figure 5 The illustration shows flowcharts of example methods according to some embodiments of the present disclosure;

[0017] Figure 6 The illustrations show flowcharts of example methods according to some embodiments of the present disclosure; and

[0018] Figure 7 A simplified block diagram of an apparatus suitable for implementing embodiments of the present disclosure is shown.

[0019] In all the accompanying drawings, the same or similar reference numerals denote the same or similar elements. Detailed Implementation

[0020] The principles of this disclosure will now be described with reference to some exemplary embodiments. It should be understood that these embodiments are described for illustrative purposes only and to assist those skilled in the art in understanding and implementing this disclosure, and do not imply any limitation on the scope of the disclosure. The disclosure described herein can be implemented in various ways other than those described below.

[0021] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0022] As used herein, the term "network device" refers to a device capable of providing or hosting communication for a cell or coverage area for terminal devices. Examples of network devices include, but are not limited to, Node B (Node B or NB), Evolved Node B (eNodeB or eNB), Node B in New Radio Access (gNB), Remote Radio Unit (RRU), Radio Header (RH), Remote Radio Header End (RRH), low-power nodes (such as femtonodes, piconodes, etc.), satellite network devices, aircraft network devices, etc. For the purposes of discussion, some example embodiments will be described below with reference to eNB as an example of a network device.

[0023] As used herein, the term "terminal device" refers to any device with wireless or wired communication capabilities. Examples of terminal devices include, but are not limited to, user equipment (UE), personal computers, desktop computers, mobile phones, cellular phones, smartphones, personal digital assistants (PDAs), portable computers, tablets, wearable devices, Internet of Things (IoT) devices, Internet of Everything (IoE) devices, machine-type communication (MTC) devices or evolved MTC (eMTC) devices, devices on vehicles used for V2X communication (where X represents a pedestrian, vehicle, or infrastructure / network), image capture terminal devices (such as digital cameras), gaming terminal devices, music storage and playback devices, or internet devices that enable wireless or wired internet access and browsing, etc. In the following description, the terms "terminal device," "communication device," "terminal," "user equipment," and "UE" are used interchangeably.

[0024] The communications discussed herein can conform to any suitable wireless interface standard, including but not limited to New Radio Access (NR), Long Term Evolution (LTE), LTE Evolution, LTE-A Advanced, Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), CDMA2000, and Global System for Mobile Communications (GSM). Furthermore, such communications can be performed according to any currently known or future communication protocols. Examples of communication protocols include, but are not limited to, first-generation (1G), second-generation (2G), 2.5G, 2.75G, third-generation (3G), fourth-generation (4G), 4.5G, and fifth-generation (5G) communication protocols. The technologies described herein can be used in the aforementioned wireless networks and radio technologies, as well as other wireless networks and radio technologies.

[0025] As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “one,” and “the” are intended to include the plural forms as well. The term “comprising” and its variations should be interpreted as open-ended terms meaning “including, but not limited to.” The term “based on” should be understood as “at least partially based on.” The terms “one embodiment” and “an embodiment” should be understood as “at least one embodiment.” The term “another embodiment” should be understood as “at least one other embodiment.” The terms “first,” “second,” etc., may refer to different or the same objects. Other explicit and implicit definitions may be included below.

[0026] In some examples, values, processes, or devices are referred to as “best,” “lowest,” “highest,” “smallest,” “maximum,” or similar terms. It should be understood that such descriptions are intended to indicate that a choice can be made among many functional alternatives used, and that such a choice does not need to be better, smaller, higher, or superior to the others.

[0027] As mentioned above, MBS has been proposed. In version 17, support for new radio (NR) for MBS has been agreed upon. For example, the use of a traditional next-generation radio access network (NG-RAN) architecture to support NR MBS has been agreed upon. Figure 1 As shown, in the traditional NG-RAN architecture 100, the gNB structure is divided into two parts: gNB-CU 110 and gNB-DU 120-1 and 120-2. gNB-CU 110 and gNB-DU 120-1 and 120-2 are connected via an interface called F1. The Radio Resource Control (RRC), Serving Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP) layers reside in gNB-CU 110, while gNB-DUs (e.g., 120-1 and 120-2) maintain Radio Link Control (RLC), Media Access Control, and Physical (PHY) layer functions.

[0028] Furthermore, to support highly reliable PTM transmission, RLC Acknowledgment Mode (AM) can be used for PTM Multicast Data Radio Bearer (DRB). Since terminal devices can trigger RLC status reports in the event of a lost RLC Protocol Data Unit (PDU), one way to implement Automatic Repeat Request (ARQ) for RLC AM PTM DRB is for the network device to retransmit lost data packets until all associated terminal devices have successfully received them. However, on the other hand, if one terminal device in the group faces poor link conditions and consistently fails to receive data packets, it is unreasonable to maintain RLC retransmission while newly generated RLC Service Data Units (SDUs) are pending, because the RLC transmission window is defined by the last sequentially acknowledged RLCSDU sequence number (SN) plus TX_Window_Size. This can lead to wasted transmission resources and increased latency. Therefore, a new solution for retransmitting lost data packets is needed to avoid resource waste.

[0029] Furthermore, there are issues with the initialization of RLC and PDCP state variables used for PTM DRB. Traditionally, most RLC and PDCP state variables used for uplink and downlink are initialized to 0. However, for MBS service, terminal devices can join an ongoing MBS session (i.e., the network device has already established a PTM DRB and has been transmitting MBS data packets in the downlink for some time), so the initially received RLC / PDCP SDU may no longer be 0. Maintaining state variables in the PTM DRB with initial values ​​of 0 can cause problems. Therefore, the initialization of state variables used for MBS needs further investigation.

[0030] Embodiments of this disclosure provide a solution for operating a PTM radio bearer. According to embodiments of this disclosure, a terminal device monitors multiple data packets transmitted from a network device on a first radio bearer. If reception of at least one of the multiple data packets fails, the terminal device can discard the at least one data packet without requesting a retransmission. The terminal device may decide to discard the at least one data packet at its own discretion. Alternatively, if the terminal device receives a discard instruction from the network device, the terminal device may discard the at least one data packet. The network device may maintain a transmission window and determine the retransmission of the data packet to be skipped if the sequence number of the data packet requesting retransmission indicated in the status report is outside the transmission window. This avoids retransmitting a data packet too many times.

[0031] The following will refer to Figure 2-7 Some exemplary embodiments of this disclosure are described in detail below.

[0032] Example Environment

[0033] Figure 2 The illustration shows a schematic diagram of a communication system 200 that can be implemented according to an embodiment of the present disclosure. The communication system 200, as part of a communication network, includes terminal devices 210-1, 210-2, ..., 210-N, which can be collectively referred to as "(a plurality of) terminal devices 210". The number N can be any suitable integer.

[0034] The communication system 200 also includes a network device 220. For example, the network device may be a gNB. In the communication system 200, the network device 220 and the terminal device 210 can transmit data and control information to each other. Figure 2 The number of terminal devices and network devices shown is given for illustrative purposes and does not imply any limitation.

[0035] Communication in communication system 200 can be implemented according to any suitable communication protocol, including but not limited to cellular communication protocols such as first-generation (1G), second-generation (2G), third-generation (3G), fourth-generation (4G), and fifth-generation (5G), wireless local area network communication protocols such as IEEE 802.11, and / or any other currently known or to be developed in the future. Furthermore, the communication can utilize any suitable wireless communication technology, including but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple Access (OFDMA), and / or any other currently known or to be developed in the future.

[0036] Example process

[0037] The following will describe in detail some example procedures used to operate radio bearers. Now refer to Figure 3 . Figure 3 The illustration shows a signaling diagram illustrating an exemplary process 300 for operating a radio bearer according to some embodiments of the present disclosure. For the purposes of this discussion, reference will be made to... Figure 2 Describe process 300. Process 300 may include, for example: Figure 2 The diagram shows terminal device 210-1 and network device 220.

[0038] Network device 220 transmits 3005 data packets to terminal device 210-1 over a first radio bearer. The first radio bearer may be a PTM radio bearer. Terminal device 210-1 monitors 3010 data packets over the first radio bearer. For example, network device 220 may transmit RLC PDUs over the first radio bearer. Alternatively or additionally, RLC SDUs may be transmitted over the first radio bearer.

[0039] Terminal device 210-1 determines whether at least one of a plurality of data packets has failed to be received. If a reception failure occurs, terminal device 210-1 determines 3012 whether a retransmission condition for the at least one data packet has not been met. For example, terminal device 210-1 may compare the number of reception failures for the at least one data packet with a threshold number. If the number of reception failures is less than the threshold number, the retransmission condition is met. Alternatively, if the number of reception failures exceeds the threshold number, the retransmission condition is not met.

[0040] In some embodiments, terminal device 210-1 may update the receive window 3015 based on the SN of the next data packet following multiple data packets. For example, the receive window may be defined by [RX_NEXT_HIGHEST - AM_WINDOW_SIZE, RX_NEXT_HIGHTEST], where RX_NEXT_HIGHEST represents the value of the SN following the SN of the RLC SDU with the highest SN among the received RLC SDUs. If at least one data packet falls outside the receive window, the retransmission condition is not met. Alternatively, if at least one data packet falls within the receive window, the retransmission condition is met. In this way, the receive window remains updated regardless of the lost data packets, thereby avoiding requests to retransmit lost data packets outside the receive window.

[0041] If the retransmission condition is not met, terminal device 210-1 discards the at least one data packet without retransmission. In some embodiments, for a given MBS session transmitted via a first radio bearer, if the reception of one or more RLCPDU / SDUs fails consecutively, terminal device 210-1 may discard the lost(multiple)RLC PDU / SDU(s) without requesting retransmission of the same(multiple)RLC PDU / SDU(s). In another embodiment, an RLC SDU may include multiple RLC PDUs. The reception of an RLCSDU fails due to the loss of an RLC PDU. In this case, if the retransmission condition is not met, terminal device 210-1 may discard the entire RLC SDU, including those RLC PDUs that have been received so far. For example, as described above, if the number of reception failures exceeds a threshold number, terminal device 210-1 may discard the at least one data packet.

[0042] In other embodiments, if at least one data packet falls outside the receive window, that at least one data packet may be discarded by the terminal device 210-1. For example, the terminal device 210-1 may discard data packets whose sequence number (SN) is less than RX_NEXT_HIGHEST-AM_WINDOW_SIZE and are still in the buffer. In some embodiments, the network device 220 may send an indication to the terminal device 210-1 to discard lost data packets preceding a sequence number equal to X.

[0043] In the example embodiment, terminal device 210-1 can update relevant state variables. For example, the parameter RX_NEXT can be updated to the value of SN, which is the value after the last fully received data packet in sequence following the discarded data packet.

[0044] Terminal device 210-1 may send a 3025 status report to network device 220. In some embodiments, the status report may indicate an acknowledgment associated with a set of data packets within the receive window. In some embodiments, the acknowledgment may indicate an ACK associated with a set of data packets. Alternatively, the acknowledgment may indicate a NACK associated with the set of data packets. Therefore, status reports for data packets(s) outside the receive window are not sent, and retransmissions of data packets(s)(s) are skipped, thereby avoiding retransmissions of data packets(s) outside the receive window(s).

[0045] In some embodiments, as described above, terminal device 210-1 can compare the number of times at least one data packet reception failed with a threshold number. For example, the threshold number can be pre-configured at terminal device 210-1. Alternatively, network device 220 can send information indicating the threshold number to terminal device 210-1. In an example embodiment, if the number of failures is less than the threshold number for at least one data packet, terminal device 210-1 can request retransmission of that data packet(s). This avoids retransmitting the data packet(s) too many times.

[0046] Alternatively, if the number of reception failures exceeds a threshold, a failure message indicating reception failure can be generated. Terminal device 210-1 can send a 3035 failure message to network device 220. In some embodiments, the failure message can be sent via RRC signaling. Therefore, the UE is prevented from continuing to send RLC status reports requesting retransmission of the same missed / lost RLC SDU or PDU.

[0047] In other embodiments, if the number of reception failures exceeds a threshold number, terminal device 210-1 may release the first radio bearer 3040. Alternatively, the first radio bearer may be released after terminal device 210-1 receives an instruction to release the first radio bearer from network device 220.

[0048] In some embodiments, terminal device 210-1 can switch from a first radio bearer to a second radio bearer based on configuration information. For example, if the number of reception failures exceeds a threshold, terminal device 210-1 can switch from the first radio bearer to the second radio bearer. Alternatively, if terminal device 210-1 receives a handover instruction, it can switch from the first radio bearer to the second radio bearer. In some embodiments, the configuration of the second radio bearer can be pre-configured at terminal device 210-1. Alternatively, network device 220 can send the configuration information of the second radio bearer to terminal device 210-1. In other embodiments, terminal device 210-1 can request the configuration information of the second radio bearer from network device 220. During handover, terminal device 210-1 can deliver SDUs associated with multiple data packets to a layer above the RLC layer, such as the PDCP layer. In some embodiments, the RLC receive buffer can be cleared. This can improve transmission performance.

[0049] In an example embodiment, network device 220 may send an indication to terminal device 210-1 to disable ARQ operation. Terminal device 210-1 may then disable ARQ operation based on this indication. This avoids the UE continuing to request retransmissions of the same missed / lost RLC PDU.

[0050] Terminal device 210-1 can set one or more state variables 3050 based on the first received data packet among multiple data packets. For example, the initial RLC state of the first radio bearer can be set. Alternatively or additionally, the initial PDCP state of the first radio bearer can be set. This avoids the problem of initializing state variables to zero.

[0051] In some embodiments, terminal device 210-1 may initialize one or more of the following based on the first received data packet: a receive state variable, a t-reassembly state variable, a maximum state transmission state variable, a highest receive state variable, an unacknowledged mode (UM) receive state variable, a UMt-reassembly state variable, or a UM receive state variable. In other embodiments, one or more of the following may be initialized based on the first received data packet: a first state variable indicating the count value of the next PDCP Service Data Unit (SDU) expected to be received, or a second state variable indicating the count value of a PDCP SDU that was not delivered to a layer higher than the PDCP layer.

[0052] Now for reference Figure 4 . Figure 4 The illustration shows a signaling diagram illustrating an exemplary process 400 for operating a radio bearer according to some embodiments of the present disclosure. Reference will be made to this diagram for discussion purposes. Figure 2 Describe process 400. Process 400 may involve, for example, Figure 2 The terminal device 210-1 and network device 220 are shown.

[0053] Network device 220 transmits 4005 multiple data packets to terminal device 210-1 over a first radio bearer. In some embodiments, the first radio bearer may be a PTM radio bearer. Network device 220 determines 4010 whether a retransmission condition for at least one of the multiple data packets has not been met. If the retransmission condition has not been met, at least one data packet may be retransmitted. Alternatively, if the retransmission condition has not been met, the retransmission of at least one data packet may be skipped. This avoids transmitting a particular data packet too many times.

[0054] In an example embodiment, network device 220 may monitor failure information recorded by terminal device 210-1 for a predetermined duration. The failure information may indicate a failure to receive at least one data packet. In some embodiments, the failure information may be a status report. If network device 220 does not receive failure information from terminal device 210-1, network device 220 may determine that the retransmission condition has not been met.

[0055] In some embodiments, network device 220 may determine a transmission window of 4015. The transmission window may be larger than the reception window maintained at each receiving terminal device. In some embodiments, if a 12-bit SN is used, the size of the reception window may be 2048. Alternatively, if an 18-bit SN is used, the size of the reception window may be 131072. In some embodiments, the transmission window for the first radio bearer may be 2. rlc-SN-SizeDL -X, where X is not less than 0 and rlc-SN-SizeDL represents the serial number.

[0056] In some embodiments, terminal device 210-1 may send a 4020 status report to network device 220. This status report can be used to request retransmission of one or more data packets with a sequence number (SN). If the SN falls within the transmission window, network device 220 may retransmit one or more data packets.

[0057] Alternatively, if the SN falls outside the transmission window, network device 220 may skip the retransmission of one or more data packets. In some embodiments, network device 220 may send an instruction 4030 to release the first radio bearer. Terminal device 210-1 may release the first radio bearer 4035 based on this instruction.

[0058] In some example embodiments, network device 220 may send 4040 an indication to switch from a first radio bearer to a second radio bearer. For example, the second radio bearer may be a PTM radio bearer. Alternatively, the second radio bearer may be a different type of radio bearer, such as a PTP AM radio bearer, a UM radio bearer, or a PTM RLC UM radio bearer. In some embodiments, configuration information of the second radio bearer may be sent to terminal device 210-1. Alternatively, the configuration information of the second radio bearer may be pre-configured at terminal device 210-1. Terminal device 210-1 may switch 4045 to the second radio bearer. During the switchover, terminal device 210-1 may deliver SDUs associated with multiple data packets to a layer above the RLC layer. In some embodiments, the RLC receive buffer may be cleared.

[0059] Network device 220 can send a 4050 instruction to disable ARQ operation at terminal device 210-1. Terminal device 210-1 can disable 4055 ARQ operation. The first radio bearer can then begin operating like the UM radio bearer.

[0060] Network device 220 may send a 4060 drop instruction to terminal device 210-1. For example, the drop instruction may indicate the dropping of data packets preceding a certain sequence number N. Sequence number N may be the lower limit of the current transmission window. In an example embodiment, terminal device 210-1 may update relevant state variables. For example, the parameter RX_NEXT may be updated to the value of SN, which is the value after the last sequentially received data packet following the dropped data packet.

[0061] Terminal device 210-1 can set one or more state variables 4070 based on the first received data packet among multiple data packets. For example, the initial RLC state of the first radio bearer can be set. Alternatively or additionally, the initial PDCP state of the first radio bearer can be set. This avoids the problem of initializing state variables to zero.

[0062] In some embodiments, terminal device 210-1 may initialize one or more of the following based on the first received data packet: a receive state variable, a t-reassembly state variable, a maximum state transmission state variable, a maximum receive state variable, an unacknowledged mode (UM) receive state variable, a UMt-reassembly state variable, or a UM receive state variable. In other embodiments, one or more of the following may be initialized based on the first received data packet: a first state variable indicating the count value of the next PDCP Service Data Unit (SDU) expected to be received, or a second state variable indicating the count value of a first PDCP SDU that has not been delivered to a layer higher than the PDCP layer.

[0063] Example Method

[0064] Figure 5 A flowchart illustrating an example method 500 according to some embodiments of the present disclosure is shown. Method 500 can be... Figure 2 The terminal device 110 shown performs this operation. It should be understood that method 500 may include additional boxes not shown and / or some boxes shown may be omitted, and the scope of this disclosure is not limited thereto. For purposes of discussion, reference will be made to... Figure 2 Method 500 is described from the perspective of terminal device 110.

[0065] In box 510, terminal device 210-1 monitors multiple data packets received from network devices on a first radio bearer. For example, an RLC PDU may be transmitted on the first radio bearer. Alternatively or additionally, an RLC SDU may be transmitted on the first radio bearer. The first radio bearer may be a PTM radio bearer.

[0066] In block 520, terminal device 210-1 determines that at least one of a plurality of data packets has failed to be received. In block 530, terminal device 210-1 determines whether a retransmission condition for the at least one data packet has not been met. If a reception failure occurs, terminal device 210-1 determines 3012 whether a retransmission condition for the at least one data packet has not been met. For example, terminal device 210-1 may compare the number of reception failures for the at least one data packet with a threshold number. If the number of reception failures is less than the threshold number, the retransmission condition is met. Alternatively, if the number of reception failures exceeds the threshold number, the retransmission condition is not met.

[0067] In some embodiments, terminal device 210-1 may update the receive window based on the SN of the next data packet following multiple data packets. For example, the receive window may be defined by [RX_NEXT_HIGHEST - AM_WINDOW_SIZE, RX_NEXT_HIGHTEST], where RX_NEXT_HIGHEST represents the value of the SN following the SN of the RLC SDU with the highest SN among the received RLC SDUs. If at least one data packet falls outside the receive window, the retransmission condition is not met. Alternatively, if at least one data packet falls within the receive window, the retransmission condition is met. In this way, the receive window remains updated regardless of the lost data packets, thereby avoiding requests to retransmit lost data packets.

[0068] In block 540, based on the determination that the retransmission condition is not met, terminal device 210-1 discards at least one data packet without requesting a retransmission. In some embodiments, for a given MBS session transmitted via a first radio bearer, if the reception of one or more RLC PDUs / SDUs fails consecutively, terminal device 210-1 may discard the lost RLC PDU(s)(s)(s)(s)) without requesting a retransmission of the same RLC PDU / SDU. In another embodiment, an RLC SDU may include multiple RLC PDUs. The reception of an RLC SDU fails due to the loss of an RLC PDU. In this case, if the retransmission condition is not met, terminal device 210-1 may discard the entire RLC SDU, including those RLC PDUs that have been received so far. For example, as described above, if the number of reception failures exceeds a threshold number, terminal device 210-1 may discard the at least one data packet.

[0069] In other embodiments, if at least one data packet falls outside the receive window, terminal device 210-1 may discard the at least one data packet. For example, terminal device 210-1 may discard data packets whose SN is less than RX_NEXT_HIGHEST-AM_WINDOW_SIZE and are still in the buffer. In some embodiments, network device 220 may send an indication to terminal device 210-1 to discard lost data packets prior to SN "X".

[0070] In the example embodiment, terminal device 210-1 can update relevant state variables. For example, the parameter RX_NEXT can be updated to the value of SN, which is the last sequentially received data packet after the discarded data packet.

[0071] Terminal device 210-1 can send a status report to network device 220. In some embodiments, the status report may indicate an acknowledgment associated with a set of data packets within the receive window. In some embodiments, the acknowledgment may indicate an ACK associated with a set of data packets. Alternatively, the acknowledgment may indicate a NACK associated with a set of data packets. Therefore, status reports for data packets(s) outside the receive window are not sent, and retransmission of data packets(s)(s) is skipped.

[0072] In some embodiments, terminal device 210-1 can compare the number of failed receptions of at least one data packet with a threshold number. For example, the threshold number can be pre-configured at terminal device 210-1. Alternatively, network device 220 can send information indicating the threshold number to terminal device 210-1. In an example embodiment, if the number of failures is below the threshold number, terminal device 210-1 can request retransmission of the at least one data packet. This avoids retransmitting data packets too many times.

[0073] Alternatively, if the number of reception failures exceeds a threshold, a failure message indicating reception failure can be generated. Terminal device 210-1 can send the failure message to network device 220. In some embodiments, the failure message can be sent via RRC signaling. Therefore, it avoids the UE maintaining an RLC status report requesting retransmission of the same missed / lost RLC SDU or PDU.

[0074] In other embodiments, if the number of reception failures exceeds a threshold number, terminal device 210-1 may release the first radio bearer. Alternatively, the first radio bearer may be released after terminal device 210-1 receives an instruction to release the first radio bearer from network device 220.

[0075] In some embodiments, terminal device 210-1 can switch from a first radio bearer to a second radio bearer based on configuration information. For example, if the number of reception failures exceeds a threshold, terminal device 210-1 can switch from the first radio bearer to the second radio bearer. Alternatively, if terminal device 210-1 receives a handover instruction, it can switch from the first radio bearer to the second radio bearer. In some embodiments, the configuration of the second radio bearer can be pre-configured at terminal device 210-1. Alternatively, network device 220 can send the configuration information of the second radio bearer to terminal device 210-1. In other embodiments, terminal device 210-1 can request the configuration information of the second radio bearer from network device 220. During handover, terminal device 210-1 can deliver SDUs associated with multiple data packets to layers above the RLC layer, such as the PDCP layer. In some embodiments, the RLC receive buffer can be cleared.

[0076] In an example embodiment, network device 220 may send an indication to terminal device 210-1 to disable ARQ operation. Terminal device 210-1 may then disable ARQ operation based on this indication. In this way, the UE avoids requesting retransmission for the same missed / lost RLC PDU.

[0077] Terminal device 210-1 can set one or more state variables based on the first received data packet among multiple data packets. For example, the initial RLC state of the first radio bearer can be set. Alternatively or additionally, the initial PDCP state of the first radio bearer can be set. This avoids the problem of initializing state variables to zero.

[0078] In some embodiments, terminal device 210-1 may initialize one or more of the following based on the first received data packet: a receive state variable, a t-reassembly state variable, a maximum state transmission state variable, a highest receive state variable, an unacknowledged mode (UM) receive state variable, a UMt-reassembly state variable, or a UM receive state variable. In other embodiments, one or more of the following may be initialized based on the first received data packet: a first state variable indicating the count value of the next PDCP Service Data Unit (SDU) expected to be received, or a second state variable indicating the count value of a first PDCP SDU that has not been delivered to a layer higher than the PDCP layer.

[0079] Figure 6 A flowchart illustrating an example method 600 according to some embodiments of the present disclosure is shown. Method 600 can be... Figure 2The network device 220 shown performs this. It should be understood that method 600 may include additional boxes not shown and / or some boxes shown may be omitted, and the scope of this disclosure is not limited thereto. For purposes of discussion, reference will be made to... Figure 2 Method 600 is described from the perspective of network device 220.

[0080] In block 610, network device 220 transmits multiple data packets to terminal device 210-1 over a first radio bearer. For example, network device 220 may transmit RLC PDUs over the first radio bearer. Alternatively or additionally, RLC SDUs may be transmitted over the first radio bearer. In some embodiments, the first radio bearer may be a PTM radio bearer.

[0081] In block 620, network device 220 determines whether a retransmission condition for at least one of a plurality of data packets has not been met. In an example embodiment, network device 220 may monitor for failure information for a predetermined duration. The failure information may indicate that the reception of at least one data packet has failed. In some embodiments, the failure information may be a status report. If network device 220 does not receive failure information, network device 220 may determine that the retransmission condition has not been met.

[0082] In some embodiments, network device 220 may determine a transmission window of 4015. The transmission window may be larger than the reception window maintained at each receiving terminal device. In some embodiments, if a 12-bit SN is used, the size of the reception window may be 2048. Alternatively, if an 18-bit SN is used, the size of the reception window may be 131072. In some embodiments, the transmission window of the first radio bearer may be 2... rlc-SN-SizeDL -X, where X is not less than 0, and rlc-SN-SizeDL represents the serial number.

[0083] In some embodiments, network device 220 may receive a status report from terminal device 210-1. The status report may be used to request the retransmission of one or more data packets with a sequence number (SN). If the SN falls within the transmission window, it means the retransmission condition has been met. Alternatively, if the SN falls outside the transmission window, it means the retransmission condition has not been met.

[0084] In block 630, if the retransmission condition is not met, network device 220 causes the retransmission of at least one data packet to be skipped. In some embodiments, network device 220 may send an indication to release the first radio bearer.

[0085] In some example embodiments, the network device 220 may send an indication to switch from a first radio bearer to a second radio bearer. For example, the second radio bearer may be a PTM radio bearer. Alternatively, the second radio bearer may be a different type of radio bearer, such as a PTP AM radio bearer, a UM radio bearer, or a PTM RLC UM radio bearer. In some embodiments, the configuration information of another radio bearer may be sent to the terminal device 210-1. Alternatively, the configuration information of the second radio bearer may be pre-configured at the terminal device 210-1.

[0086] In an example embodiment, the network device 220 may send an indication to disable the ARQ operation at the terminal device 210-1. Alternatively or additionally, the network device 220 may send a 4060 discard indication to the terminal device 210-1. For example, the discard indication may indicate to discard data packets before a certain sequence number N. The sequence number N may be the lower boundary of the current transmission window.

[0087] Specific embodiments 1-4 of the method illustrated and shown as any of Figure 3-6 are described below.

[0088] Embodiment 1

[0089] In this embodiment, for a given MBS session transmitted on a PTM radio bearer, when the RLC PDU / SDU reception fails continuously for a certain period of time, the terminal device 210-1 may discard the lost RLC PDU / SDU without requesting retransmission of the same RLC PDU / SDU. For example, the PTM radio bearer reception window may be defined by [RX_NEXT_HIGHEST-AM_WINDOW_SIZE, RX_NEXT_HIGHTEST], where RX_NEXT_HIGHEST represents the value of the SN after the SN of the RLC SDU with the highest SN among the received RLC SDUs. The terminal device 210-1 may keep updating the RX_NEXT_HIGHEST value when receiving a new RLC SDU. The terminal device 210-1 may discard the RLC SDU segments still in the buffer while having SN < RX_NEXT_HIGHEST-AM_WINDOW_SIZE.

[0090] In addition, the terminal device 210-1 may update the relevant state variables. For example, the RX_NEXT parameter may be updated to the value of the SN after the last sequence completely received RLC SDU after the discarded RLC SDU. In the RLC status report sent to the network device 220, the terminal device 210-1 may only indicate the ACK / NACK of the RCL SDUs within the reception window.

[0091] In another example, terminal device 210-1 can be configured to handle a maximum number of reception failures for a single RLC PDU / SDU. When the number of consecutive reception failures for an RLC PDU / SDU exceeds the maximum number (N times), terminal device 210-1 can release the current PTM radio bearer. Alternatively, terminal device 210-1 can switch to another radio bearer configured by network device 220. In other embodiments, terminal device 210-1 can generate a failure information RRC message and send a message indicating RLC reception failure to network device 220.

[0092] In another example, following a series of failures in downlink RLC PDU / SDU transmissions, network device 220 may instruct terminal device 210-1 to switch from a PTM AM radio bearer to another type of radio bearer (e.g., PTP RLCAM or UM DRB, or PTM RLC UM DRB). Network device 220 may also provide the appropriate radio bearer configuration. During the radio bearer switchover, terminal device 210-1 may reassemble the RLC SDU and deliver it to the upper layer, clearing its RLC receive buffer. Optionally, terminal device 210-1 may release the old PTM RLC AM radio bearer.

[0093] Alternatively, network device 220 may send a command to terminal device 210-1 to disable ARQ operation (based on dedicated RRC signaling or MAC control element (CE) or RLC header). In other embodiments, network device 220 may instruct terminal device 210-1 to discard missed / lost RLC SDUs / PDUs one by one, for example, RLC control PDUs, before the SN equals X (e.g., RLC control PDU). Terminal device 210-1 may update relevant status variables. For example, the RX_NEXT parameter may be updated to the value of the SN after the last fully received RLC SDU in sequence after the discarded RLC SDU.

[0094] Example 2

[0095] In this embodiment, when operating PTM RLC AM transmission in DL, network device 220 can maintain a transmission window larger than the receive window size maintained in each receiving terminal device. For example, the transmission window size can be 2 rlc -SN-SizeDL -X, where X is an appropriate integer. The sending window can be larger than the receiving window of the terminal device 210-1.

[0096] If network device 220 receives a status report from terminal device 210-1 requesting retransmission of one or more RLC PDUs / PDUs with sequence number SN, network device 220 can determine whether the sequence number SN is within the transmission window. If the sequence number SN is within the transmission window, network device 220 can retransmit the corresponding RLC PDU / PDU.

[0097] Alternatively, if the sequence number SN falls outside the transmission window, network device 220 may instruct terminal device 210-1 to switch from a PTM radio bearer to another type of radio bearer (e.g., PTP RLC AM or UM DRB, or PTM RLC UM DRB) and provide the appropriate radio bearer configuration. During the radio bearer switchover, terminal device 210-1 may reassemble and deliver the RLC SDU to the upper layer and clear its RLC receive buffer. Optionally, terminal device 210-1 may release the old PTM RLC AM radio bearer. Alternatively, network device 220 may send a command to terminal device 210-1 to disable ARQ operation (according to dedicated RRC signaling or MAC control element (CE) or RLC header). In other embodiments, network device 220 may instruct terminal device 210-1 to discard missed / lost RLC SDUs / PDUs before SN=X on an RLC control PDU-by-Round basis. Terminal device 210-1 may update relevant status variables. For example, the RX_NEXT parameter can be updated to the value of the SN following the last fully received RLC SDU after the discarded RLCSDU.

[0098] Example 3

[0099] In this embodiment, when the terminal device 210-1 is configured with a PTM radio bearer, the RLC state variables can be initialized based on the first received data packet among a plurality of data packets.

[0100] The receiver side of each AM RLC entity should maintain the following state variables:

[0101] (a) Rx_Next — Receive Status Variable. This status variable stores the value of the SN following the last fully received RLCSDU in sequence, and it serves as the lower edge of the receive window. It is initially set to 0 and is updated whenever an AM RLC entity receives an RLC SDU with SN = RX_Next. For PTM SRB / DRB, it is initially set to the SN of the first received Acknowledgment Mode Data PDU (AMD PDU) containing the SN.

[0102] (b) Rx_Next_Status_Trigger — t-reorganization status variable. This status variable stores the value of the SN after the SN of the RLC SDU that triggers t-reorganization.

[0103] (c) Rx_Highest_Status — Maximum STATUS transmission status variable. This status variable holds the highest possible value of the SN that can be indicated by "ACK_SN" when a STATUS PDU needs to be constructed. It is initially set to 0. For PTM SRB / DRB, it is initially set to the SN of the first received AMD PDU containing the SN.

[0104] (d) Rx_Next_Highest — Highest Received Status Variable. This status variable holds the value of the SN following the SN of the RLC SDU with the highest SN among the received RLC SDUs. It is initially set to 0. For PTM SRB / DRB, it is initially set to the SN of the first received AMD PDU containing the SN.

[0105] Each receiving UM RLC entity should maintain the following state variables:

[0106] (a) RX_Next_Reassembly — UM Receive Status Variable. This status variable retains the value of the earliest SN still considered for reassembly. It is initially set to 0. For multicast and broadcast communication on NR sidelinks, it is initially set to the SN of the first received UM DPDU containing the SN. For PTM SRB / DRB, it is initially set to the SN of the first received UM DPDU containing the SN.

[0107] (b) Rx_Timer_Trigger—UMt—Reassembles the state variable. This state variable retains the value of the SN after the trigger t reassembly.

[0108] (c) Rx_Next_highest — UM Receive Status Variable. This status variable stores the value of the SN following the SN of the UMD PDU with the highest SN among the received UMD PDUs. It is used as the higher edge of the reassembly window. It is initially set to 0. For multicast and broadcast of NR sidelink communication, it is initially set to the SN of the first received UMD PDU containing the SN. For PTM SRB / DRB, it is initially set to the SN of the first received UMD PDU containing the SN.

[0109] Example 4

[0110] In this embodiment, if the terminal device 210-1 is configured with a PTM radio bearer, the PDCP state variables are initialized based on the first received PDCP PDU.

[0111] The entity receiving the PDCP should maintain the following state variables:

[0112] (a) Rx_NEXT. This state variable indicates the COUNT value of the next PDCP SDU expected to be received. The initial value is 0, except for sidelink broadcast and multicast, and is for SRBs configured with persistent state variables. For NR sidelink communication used for broadcast and multicast, the initial value of the SN portion of RX_NEXT is (x+1) modulo (2). [sl-PDCP-SNSize] ), where x is the SN of the first received PDCP Data PDU. For a target SRB configured with persistent state variables, the initial value is the value stored in the PDCP entity of the corresponding source SRB. For a source SRB configured with persistent state variables, the initial value is the value stored in the PDCP entity of the corresponding target SRB. For a PTM SRB / DRB, it is initially set to the COUNT value of the first received PDCP PDU.

[0113] (b) Rx_deliv. This state variable indicates that the COUNT value of the first PDCP SDU has not been delivered to the upper layer, but is still waiting. The initial value is 0, except for sidelink broadcast and multicast, and for SRBs configured with persistent state variables. For NR sidelink communication used for broadcast and multicast, the initial value of the SN portion of RX_DELI is (x - 0.5 × 2). [sl -PDCP-SN-Size-1] )m2 [sl-PDCP-SN-Size] ), where x is the SN of the first received PDCP Data PDU. For a target SRB configured with persistent state variables, the initial value is the value stored in the PDCP entity of the corresponding source SRB. For a source SRB configured with persistent state variables, the initial value is the value stored in the PDCP entity of the corresponding target SRB. For PTMSRB / DRB, the initial value of RX_DELIV's HFN is set to the HFN value of the first received PDCPPDU, and the initial value of RX_DELIV's SN is set to (x - 0.5 × 2). [PDCP-SN-Size-1] )m2 [PDCP-SN-Size] ), where x is the SN of the first received PDCP PDU.

[0114] (c) Rx_reord. This state variable indicates the COUNT value following the COUNT value associated with the PDCP data PDU that triggered the t-reordering. For a target SRB configured with state variable persistence, the initial value is the value stored in the PDCP entity of the corresponding source SRB.

[0115] Example device

[0116] Figure 7 This is a simplified block diagram of an apparatus 700 suitable for implementing embodiments of the present disclosure. The apparatus 700 can be considered as follows: Figure 1 Another example implementation of the terminal device 110, network device 120, or network device 130 shown. Therefore, the device 700 may be implemented at or as a part of the terminal device 110, network device 120, or network device 130.

[0117] As shown in the figure, device 700 includes a processor 710, a memory 720 coupled to the processor 710, and suitable transmitters (TX) and receivers (RX) 740 coupled to the processor 710. The memory 720 stores at least a portion of a program 730. The TX / RX 740 is used for bidirectional communication. The TX / RX 740 is coupled to at least one antenna to facilitate communication; however, in practice, the access node mentioned in this application may have several antennas. The communication interface can represent any interface required for communication with other network elements, such as an X2 interface for bidirectional communication between eNBs, an S1 interface for communication between a Mobility Management Entity (MME) / Serving Gateway (S-GW) and an eNB, an Un interface for communication between an eNB and a relay node (RN), or a Uu interface for communication between an eNB and a terminal device.

[0118] Assuming program 730 includes program instructions that, when executed by the associated processor 710, enable device 700 to operate according to embodiments of this disclosure, as referenced herein. Figure 2-6 The embodiments discussed herein can be implemented by computer software executable by the processor 710 of device 700, or by hardware, or by a combination of software and hardware. The processor 710 can be configured to implement various embodiments of the invention. Furthermore, a combination of the processor 710 and the memory 720 can form a processing unit 750 suitable for implementing various embodiments of this disclosure.

[0119] Memory 720 can be of any type suitable for a local technology network and can be implemented using any suitable data storage technology, such as, as non-limiting examples, non-transitory computer-readable storage media, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. Although only one memory 720 is illustrated in device 700, several physically different memory modules may be present in device 700. As a non-limiting example, processor 710 can be of any type suitable for a local technology network and may include one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. Device 700 may have multiple processors, such as application-specific integrated circuit chips that are time-dependent on a clock that synchronizes with the main processor.

[0120] In some embodiments, the means for performing method 500 (e.g., terminal device 210-1) may include corresponding components for performing corresponding steps in method 500. These components may be implemented in any suitable manner. For example, they may be implemented by circuitry or software modules.

[0121] In some embodiments, the apparatus includes: components for monitoring a plurality of data packets transmitted from a network device over a first radio bearer; components for determining that at least one of the plurality of data packets has failed to be received; components for determining whether a retransmission condition for at least one data packet has not been met; and components for discarding at least one data packet without requesting a retransmission based on the determination that the retransmission condition has not been met.

[0122] In some embodiments, the component for determining whether a retransmission condition for at least one data packet is not met includes: a component for updating a receive window for a plurality of data packets based on the sequence number of the next data packet following the plurality of data packets; and a component for determining that the retransmission condition is not met based on determining that at least one data packet is outside the receive window.

[0123] In some embodiments, the apparatus further includes components for sending a status report to a network device, the status report indicating an acknowledgment associated with a set of data packets received within a receiving window.

[0124] In some embodiments, the apparatus further includes components for comparing the number of reception failures of at least one data packet with a threshold number; components for generating failure information based on determining that the number of reception failures exceeds the threshold number; and components for sending the failure information to a network device.

[0125] In some embodiments, the apparatus further includes components for comparing the number of reception failures of at least one data packet with a threshold number; and components for performing at least one of the following based on the determination that the number of reception failures exceeds the threshold number: releasing a first radio bearer; or switching from the first radio bearer to a second radio bearer.

[0126] In some embodiments, the apparatus further includes components for receiving configuration information of a second radio bearer from a network device; components for receiving an indication from the network device to switch from a first radio bearer to a second radio bearer; and components for switching from a first radio bearer to a second radio bearer based on the configuration information.

[0127] In some embodiments, the components for switching from a first radio bearer to a second radio bearer include: components for delivering Service Data Units (SDUs) associated with a plurality of data packets to a layer above the Radio Link Control (RLC) layer; and components for clearing the RLC receive buffer.

[0128] In some embodiments, the apparatus further includes a component for receiving from a network device an instruction to disable the Automatic Repeat Request (ARQ) operation at the terminal device.

[0129] In some embodiments, a component is used to set at least one of the following based on a first received data packet among a plurality of data packets: the initial radio link control (RLC) state of the first radio bearer or the initial packet data convergence protocol (PDCP) state of the first radio bearer.

[0130] In some embodiments, the initial RLC state of the first radio bearer includes at least one of the following: receive state variable, t-recombination state variable, maximum condition transmit state variable, highest receive state variable, unacknowledged mode (UM) receive state variable, UMt-recombination state variable, or UM receive state variable.

[0131] In some embodiments, the initial PDCP state of the first radio bearer includes at least one of the following: a first state variable indicating the count value of the next PDCP service data unit (SDU) expected to be received, or a second state variable indicating the count value of the first PDCP SDU that has not been delivered to a layer above the PDCP layer.

[0132] In some embodiments, the apparatus for performing method 600 (e.g., network device 220) may include corresponding components for performing the corresponding steps in method 300. These components may be implemented in any suitable manner. For example, they may be implemented by circuitry or software modules.

[0133] In some embodiments, the apparatus includes components for transmitting a plurality of data packets to a terminal device over a first radio bearer; components for determining whether a retransmission condition for at least one of the plurality of data packets has not been met; and components for skipping the retransmission of at least one data packet based on the determination that the retransmission condition has not been met.

[0134] In some embodiments, the apparatus further includes components for determining a transmission window for a plurality of data packets; components for receiving failure information from a terminal device indicating that at least one data packet has failed to be received; and components for determining whether a retransmission condition for at least one of the plurality of data packets has not been met, including: components for determining that the retransmission condition is met based on determining that the sequence number of at least one data packet falls within the transmission window; or components for determining that the retransmission condition is not met based on determining that the sequence number of at least one data packet falls outside the transmission window.

[0135] In some embodiments, the component for causing retransmission of at least one data packet to be skipped includes: a component for causing retransmission of at least one data packet to be skipped based on determining that the sequence number of at least one data packet falls outside the transmission window.

[0136] In some embodiments, the apparatus further includes a component for retransmitting at least one data packet on a first radio bearer based on determining that the sequence number of at least one data packet falls within a transmission window.

[0137] In some embodiments, the component for determining whether a retransmission condition for at least one of a plurality of data packets has not been met includes: a component for monitoring failure information indicating a reception failure of at least one data packet for a predetermined duration; and a component for determining that the retransmission condition has not been met based on the determination of reception failure indicated in the failure information.

[0138] In some embodiments, the apparatus further includes: a component for sending configuration information of a second radio bearer to a terminal device based on determining that a retransmission condition has not been met; and a component for sending an indication to the terminal device to switch from a first radio bearer to a second radio bearer.

[0139] In some embodiments, the apparatus further includes a component for sending an instruction to a terminal device to disable the Automatic Repeat Request (ARQ) operation at the terminal device based on the determination that the retransmission condition has not been met.

[0140] In some embodiments, the apparatus further includes a component for sending a discard instruction to a terminal device to discard the at least one data packet based on a determination that the retransmission condition has not been met.

[0141] Generally, the various embodiments of this disclosure can be implemented using hardware or dedicated circuitry, software, logic, or any combination thereof. Some aspects can be implemented using hardware, while others can be implemented using firmware or software that can be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of this disclosure are illustrated and described as block diagrams, flowcharts, or using some other graphical representation, it should be understood that, as non-limiting examples, the blocks, apparatuses, systems, techniques, or methods described herein can be implemented using hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof.

[0142] This disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions included in a program module, which execute in a device on a target real or virtual processor to perform the above-referenced... Figure 3-6 A described process or method. Typically, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc., that perform specific tasks or implement specific abstract data types. In various embodiments, the functionality of a program module can be combined or split among program modules as needed. The machine-executable instructions of a program module can execute on a local or distributed device. In a distributed device, a program module can reside on both local and remote storage media.

[0143] Program code used to perform the methods of this disclosure may be written in any combination of one or more programming languages. This program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a machine, partially on a machine, as a stand-alone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0144] The aforementioned program code may be embodied on a machine-readable medium, which can be any tangible medium that may contain or store a program for or related to an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media may include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media will include electrical connections having one or more wires, portable computer floppy disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable optical disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0145] Furthermore, although operations are described in a specific order, this should not be construed as requiring the operations to be performed in the specific order shown or sequentially, or to perform all of the shown operations to obtain the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the foregoing discussion, these should not be construed as limiting the scope of this disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features described in the context of a single embodiment may also be implemented in combination in a single embodiment. Conversely, the various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0146] Although this disclosure has been described in language specific to structural features and / or methodological actions, it should be understood that this disclosure as defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are disclosed as exemplary forms of implementing the claims.

Claims

1. A terminal device, comprising: processor; as well as A transceiver coupled to the processor, and the processor is configured to: Monitoring multiple data packets received from a network device on a first radio bearer, wherein the first radio bearer is a point-to-multipoint radio bearer; Based on the first received data packet among the plurality of data packets, set one or more state variables of the first radio bearer; Determine that at least one of the plurality of data packets has failed to be received; Based on the receive window, it is determined whether the retransmission condition for the at least one data packet has not been met, wherein the higher edge of the receive window is defined based on the unacknowledged mode (UM) receive state variable among the one or more state variables. as well as If it is determined that the retransmission condition is not met, the at least one data packet is discarded without requesting a retransmission.

2. The terminal device of claim 1, wherein the processor is configured to determine whether the retransmission condition for the at least one data packet is not met by: Based on the sequence number of the next data packet following the plurality of data packets, update the receiving window for the plurality of data packets; and Based on the determination that at least one data packet is outside the receiving window, it is determined that the retransmission condition has not been met.

3. The terminal device according to claim 2, wherein the processor is further configured to: A status report is sent to the network device, the status report indicating an acknowledgment associated with a set of data packets received within the receiving window.

4. The terminal device according to claim 1, wherein the processor is further configured to: The number of times the reception of the at least one data packet failed is compared with a threshold number; A failure message is generated based on the number of times the number of reception failures exceeds the threshold; and The failure information is sent to the network device.

5. The terminal device according to claim 1, wherein the processor is further configured to: The number of times the reception of the at least one data packet failed is compared with a threshold number; Based on the number of times the reception failure is determined to have exceeded the threshold, perform at least one of the following: Release the first radio bearer; or Switch from the first radio bearer to the second radio bearer.

6. The terminal device according to claim 1, wherein the processor is further configured to: Receive configuration information of the second radio bearer from the network device; Receive an instruction from the network device to switch from the first radio bearer to the second radio bearer; as well as Based on the configuration information, the system switches from the first radio bearer to the second radio bearer.

7. The terminal device according to claim 5 or claim 6, wherein the processor is configured to switch from the first radio bearer to the second radio bearer by: The Service Data Units (SDUs) associated with the plurality of data packets are delivered to the logical layer above the Radio Link Control (RLC) layer; and Clear the RLC receive buffer.

8. The terminal device according to claim 1, wherein the processor is further configured to: The network device receives an instruction to disable the Automatic Repeat Request (ARQ) operation at the terminal device.

9. The terminal device of claim 1, wherein the processor is configured to set the one or more state variables by: Based on the first received data packet among the plurality of data packets, at least one of the following is set: the initial radio link control (RLC) state of the first radio bearer or the initial packet data convergence protocol (PDCP) state of the first radio bearer.

10. The terminal device of claim 9, wherein the initial RLC state of the first radio bearer further includes at least one of the following: Receive state variables, t-reorganization state variable, or Send status variables in the maximum condition.

11. The terminal device of claim 9, wherein the initial PDCP state of the first radio bearer includes at least one of the following: The first state variable indicates the count value of the next PDCP Service Data Unit (SDU) expected to be received, or The second state variable indicates the count value of the first PDCP SDU that has not been delivered to the layer above the PDCP layer.

12. A network device, comprising: processor; as well as A transceiver coupled to the processor, and the processor is configured to: Multiple data packets are transmitted to a terminal device on a first radio bearer, wherein the first radio bearer is a point-to-multipoint radio bearer, and one or more state variables of the first radio bearer are set based on the first data packet received at the terminal device in the multiple data packets; Based on the sending window, it is determined whether the retransmission condition for at least one of the plurality of data packets has not been met, wherein the sending window is larger than the receiving window maintained at the terminal device. as well as If the retransmission condition is determined not to be met, the retransmission of the at least one data packet is skipped.

13. The network device of claim 12, wherein the processor is further configured to: Determine the transmission window for the plurality of data packets; Receive from the terminal device a failure message indicating that the reception of at least one data packet has failed; and Determining whether the retransmission condition for at least one of the plurality of data packets is not met includes: The retransmission condition is determined to be satisfied based on the fact that the sequence number of the at least one data packet falls within the transmission window; or The retransmission condition is determined not to be met based on the fact that the sequence number of the at least one data packet falls outside the transmission window.

14. A method executed by a terminal device, comprising: Monitoring multiple data packets received from a network device on a first radio bearer, wherein the first radio bearer is a point-to-multipoint radio bearer; Based on the first received data packet among the plurality of data packets, set one or more state variables of the first radio bearer; Determine that at least one of the plurality of data packets has failed to be received; Based on the receive window, it is determined whether the retransmission condition for the at least one data packet has not been met, wherein the higher edge of the receive window is defined based on the unacknowledged mode (UM) receive state variable among the one or more state variables. as well as If it is determined that the retransmission condition is not met, the at least one data packet is discarded without requesting a retransmission.

15. The method of claim 14, wherein determining whether the retransmission condition for the at least one data packet is not satisfied comprises: The receiving window for the multiple data packets is updated based on the sequence number of the next data packet following the multiple data packets; as well as Based on the determination that at least one data packet is outside the receiving window, it is determined that the retransmission condition has not been met.

16. The method of claim 15, further comprising: A status report is sent to the network device, the status report indicating an acknowledgment associated with a set of data packets received within the receiving window.

17. The method of claim 14, further comprising: The number of times the reception of the at least one data packet failed is compared with a threshold number; A failure message is generated based on the number of times the number of reception failures exceeds the threshold. as well as The failure information is sent to the network device.

18. The method of claim 14, further comprising: The number of times the reception of the at least one data packet failed is compared with a threshold number; Based on the number of times the reception failure is determined to have exceeded the threshold, perform at least one of the following: Release the first radio bearer; or Switch from the first radio bearer to the second radio bearer.

19. The method of claim 14, further comprising: Receive configuration information of the second radio bearer from the network device; Receive an instruction from the network device to switch from the first radio bearer to the second radio bearer; as well as Based on the configuration information, the system switches from the first radio bearer to the second radio bearer.

20. The method of claim 18 or claim 19, wherein switching from the first radio bearer to the second radio bearer comprises: The Service Data Units (SDUs) associated with the plurality of data packets are delivered to the logical layer above the Radio Link Control (RLC) layer; as well as Clear the RLC receive buffer.

21. The method of claim 14, further comprising: The network device receives an instruction to disable the Automatic Repeat Request (ARQ) operation at the terminal device.

22. The method of claim 14, wherein setting the one or more state variables of the first radio bearer comprises: Based on the first received data packet among the plurality of data packets, at least one of the following is set: the initial radio link control (RLC) state of the first radio bearer or the initial packet data convergence protocol (PDCP) state of the first radio bearer.

23. The method of claim 22, wherein the initial RLC state of the first radio bearer further comprises at least one of the following: Receive state variables, t-reorganization state variable, or Send status variables in the maximum condition.

24. The method of claim 22, wherein the initial PDCP state of the first radio bearer includes at least one of the following: The first state variable indicates the count value of the next PDCP Service Data Unit (SDU) expected to be received, or The second state variable indicates the count value of the first PDCP SDU that has not been delivered to the layer above the PDCP layer.

25. A method performed by a network device, comprising: Multiple data packets are transmitted to a terminal device on a first radio bearer, wherein the first radio bearer is a point-to-multipoint radio bearer, and one or more state variables of the first radio bearer are set based on the first data packet received at the terminal device in the multiple data packets; Based on the sending window, it is determined whether the retransmission condition for at least one of the plurality of data packets has not been met, wherein the sending window is larger than the receiving window maintained at the terminal device. as well as If the retransmission condition is determined not to be met, the retransmission of the at least one data packet is skipped.

26. The method of claim 25, further comprising: Determine the transmission window for the plurality of data packets; Receive from the terminal device a failure message indicating that the reception of at least one data packet has failed; and Determining whether the retransmission condition for at least one of the plurality of data packets is not met includes: The retransmission condition is determined to be satisfied based on the fact that the sequence number of the at least one data packet falls within the transmission window; or The retransmission condition is determined not to be met based on the fact that the sequence number of the at least one data packet falls outside the transmission window.

27. A device for communication, comprising: processor; A memory, coupled to the processor and storing instructions thereon, which, when executed by the processor, cause the device to: Monitoring multiple data packets received from a network device on a first radio bearer, wherein the first radio bearer is a point-to-multipoint radio bearer; Based on the first received data packet among the plurality of data packets, set one or more state variables of the first radio bearer; Determine that at least one of the plurality of data packets has failed to be received; Based on the receive window, it is determined whether the retransmission condition for the at least one data packet has not been met, wherein the higher edge of the receive window is defined based on the unacknowledged mode (UM) receive state variable among the one or more state variables. as well as If it is determined that the retransmission condition is not met, the at least one data packet is discarded without requesting a retransmission.

28. The apparatus of claim 27, wherein the apparatus is configured to determine whether the retransmission condition for the at least one data packet is not satisfied by: Based on the sequence number of the next data packet following the plurality of data packets, update the receiving window for the plurality of data packets; and Based on the determination that at least one data packet is outside the receiving window, it is determined that the retransmission condition has not been met.

29. The apparatus of claim 27, wherein the apparatus is further configured to: A status report is sent to the network device, the status report indicating an acknowledgment associated with a set of data packets received within the receiving window.

30. The apparatus of claim 27, wherein the apparatus is further configured to: The number of times the reception of the at least one data packet failed is compared with a threshold number; A failure message is generated based on the number of times the number of reception failures exceeds the threshold; and The failure information is sent to the network device.

31. The apparatus of claim 27, wherein the apparatus is further configured to: The number of times the reception of the at least one data packet failed is compared with a threshold number; Based on the number of times the reception failure is determined to have exceeded the threshold, perform at least one of the following: Release the first radio bearer; or Switch from the first radio bearer to the second radio bearer.

32. The apparatus of claim 27, wherein the apparatus is further configured to: Receive configuration information of the second radio bearer from the network device; Receive an instruction from the network device to switch from the first radio bearer to the second radio bearer; and Based on the configuration information, the system switches from the first radio bearer to the second radio bearer.

33. The apparatus of claim 31 or claim 32, wherein the apparatus is configured to switch from the first radio bearer to the second radio bearer by: The Service Data Units (SDUs) associated with the plurality of data packets are delivered to the logical layer above the Radio Link Control (RLC) layer; and Clear the RLC receive buffer.

34. An apparatus for communication, comprising: processor; A memory, coupled to the processor and storing instructions thereon, which, when executed by the processor, cause the device to: Multiple data packets are transmitted to a terminal device on a first radio bearer, wherein the first radio bearer is a point-to-multipoint radio bearer, and one or more state variables of the first radio bearer are set based on the first data packet received at the terminal device in the multiple data packets; Based on the sending window, it is determined whether the retransmission condition for at least one of the plurality of data packets has not been met, wherein the sending window is larger than the receiving window maintained at the terminal device. as well as If the retransmission condition is determined not to be met, the retransmission of the at least one data packet is skipped.

35. The apparatus of claim 34, wherein the apparatus is further configured to: Determine the transmission window for the plurality of data packets; Receive from the terminal device a failure message indicating that the reception of at least one data packet has failed; and Determining whether the retransmission condition for at least one of the plurality of data packets is not met includes: The retransmission condition is determined to be satisfied based on the fact that the sequence number of the at least one data packet falls within the transmission window; or The retransmission condition is determined not to be met based on the fact that the sequence number of the at least one data packet falls outside the transmission window.

36. A computer-readable storage medium having program code stored thereon, the program code being configured to cause a device to perform the method according to any one of claims 14 to 24 or any one of claims 25 to 26 when executed.

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