Wireless communication method and device

Abstract

A wireless communication method may be performed in a wireless communication device. The apparatus transmits a protocol data unit (PDU) of a set of PDUs serving from a protocol layer entity to a lower layer according to a drop timer of the set of PDUs and a transmission window across a plurality of sets of PDUs.

Description

Technical Field

[0001] The present disclosure relates to the telecommunication field, and in particular to a wireless communication method and device. Background Art

[0002] Wireless communication systems, such as the third generation (3G) mobile phone standards and technologies, are well known. Such 3G standards and technologies are developed by the Third Generation Partnership Project (3GPP). The third generation of wireless communications is generally developed to support macrocellular mobile phone communications. Communication systems and networks have evolved into broadband and mobile systems. In a cellular wireless communication system, a user equipment (UE) is connected to a radio access network (RAN) via a radio link. The RAN includes a set of base stations (BS) that provide radio links for the UEs located in the cells covered by the base stations and interface with a core network (CN) that provides overall network control. It is understood that the RAN and CN each perform corresponding functions related to the overall network. The Third Generation Partnership Project developed the so-called Long Term Evolution (LTE) system, i.e., the Evolved Universal Mobile Telecommunications System Terrestrial Radio Access Network (E-UTRAN), for mobile access networks, in which one or more macro cells are supported by base stations called eNodeBs or eNBs (evolved NodeBs). Recently, LTE has evolved further towards the so-called 5G or New Radio (NR) systems, in which one or more cells are supported by base stations called gNBs. Technical issues

[0003] The 5G wireless communication system is designed to provide enhanced mobile broadband (eMBB), ultra-reliable and low-latency communication (URLLC), and massive machine type communication (MTC) services. In 5G or NR, the functions supporting eMBB, URLLC, and mMTC were introduced in Release 15 and enhanced in Releases 16 and 17.

[0004] Extended reality (XR) is an umbrella term covering augmented reality (AR), mixed reality (MR), and virtual reality (VR). XR applications typically require high throughput and low latency, and cloud gaming is another application with the same requirements. XR and cloud gaming are important applications that 5G will enable.

[0005] XR services are characterized by their special traffic flows in real time, high data rate and low latency. XR video streams contain different frames / video slices. For example, a group of pictures (GOP) includes I / P / B frames. Some special characteristics of such XR service flows should be considered and supported in 5G.

[0006] On the one hand, the data size of different frames is different, and a frame can be divided into a group of data packets. However, the application can only decode these frames / video slices when all data packets of the frame / video slice are successfully received. A group of data packets belonging to a frame / video slice (hereinafter referred to as a data packet group) should be processed as a unit.

[0007] On the other hand, some types of data packet groups may depend on other data packet groups. For example, the data packets of P frames and B frames depend on the data packets of the I frames, and the data packets of B frames depend on the data packets of the P frames. In other words, there is a dependency relationship between different data packet groups.

[0008] Since the XR service is a real-time service, the outdated data packets are usually useless and should be discarded as soon as possible. In addition, due to the dependency of the data packet group of the XR service, the outdated data packet is usually a group of data packets. In another case, if the data packet transmission fails within a predefined time, the lost data packet will also cause a group of data packets to be discarded according to the dependency. The problems include: · How to detect the failed transmission and discard the useless data packet group as soon as possible; · How to discard packets based on the dependencies between packets or other data units in an XR service. Summary of the invention

[0009] The object of the present disclosure is to provide a wireless communication method and device.

[0010] In a first aspect, an embodiment of the present invention provides a wireless communication method, which may be performed in a wireless communication device as a sending device, the method comprising: transmitting a protocol data unit (PDU) set of the service from a protocol layer entity to a lower layer based on a discard timer for the PDU set and a transmission window spanning a plurality of PDU sets; When the protocol layer entity receives a first service data unit (SDU) associated with the PDU set from a higher layer, starting the discard timer of the PDU set; When the protocol layer entity receives a subsequent service data unit (SDU) from the higher layer and a PDU set sequence number (SN) of the subsequent SDU and the PDU set is less than a minimum PDU set SN of the transmission window, discarding the subsequent SDU associated with the PDU set; generating a PDU from the subsequent SDU for transmission to the lower layer when the PDU set SN associated with the subsequent SDU is not less than the minimum PDU set SN of the transmission window and the subsequent SDU is not discarded; When all the PDUs of the PDU set are received and transmitted to the lower layer, stopping the discard timer; When the discard timer of the PDU set times out, all PDUs of the PDU set are discarded And stop the discard timer.

[0011] In a second aspect, an embodiment of the present invention provides a wireless communication device, comprising a processor configured to call and run a computer program stored in a memory, so that the device equipped with the processor executes the disclosed method.

[0012] In a sixth aspect, an embodiment of the present invention provides a wireless communication device, comprising a processor configured to call and run a computer program stored in a memory, so that the device equipped with the processor executes the disclosed method.

[0013] The disclosed method may be implemented in a chip. The chip may include a processor configured to call and run a computer program stored in a memory so that a device equipped with the chip executes the disclosed method.

[0014] The disclosed method can be programmed as computer-executable instructions stored in a non-transitory computer-readable medium. When the non-transitory computer-readable medium is loaded into a computer, it instructs the processor of the computer to execute the disclosed method.

[0015] The non-temporary computer-readable medium may include at least one of the following groups: a hard disk, a read-only compact disk (CD-ROM), an optical storage device, a magnetic storage device, a read-only memory (Read-Only Memory), a programmable read-only memory (Programmable Read-Only Memory), an erasable programmable read-only memory (ErasableProgrammable Read-Only Memory, EPROM), an electrically erasable programmable read-only memory (ElectricallyErasableProgrammableRead-OnlyMemory) and a flash memory.

[0016] The disclosed method can be programmed into a computer program product to enable a computer to execute the disclosed method.

[0017] The disclosed method can be programmed into a computer program to enable a computer to execute the disclosed method. Beneficial Effects

[0018] One embodiment of the present disclosure provides a method in which a sending device transmits a discard indication so that a receiving device can correctly handle a sequence number (SN) gap caused by group PDU discard.

[0019] One embodiment of the present disclosure provides a method in which a receiving device receives a protocol data unit (PDU) according to a discard control PDU so that PDU reception can work smoothly and correctly. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments or related technologies of the present disclosure, the drawings described in the embodiments are briefly introduced. Obviously, the drawings are only some embodiments of the present disclosure, and ordinary technicians in this field can obtain other drawings based on these drawings without paying the above premise.

[0021] Figure 1 A schematic diagram of a telecommunication system is shown.

[0022] Figure 2 A schematic diagram of a network embodiment showing the disclosed wireless communication method is shown.

[0023] Figure 3 A schematic diagram showing the protocol layers of a sending device and a receiving device.

[0024] Figure 4 A schematic diagram of a wireless communication method according to an embodiment of the present disclosure is shown.

[0025] Figure 5 A schematic diagram of a wireless communication method according to an embodiment of the present disclosure is shown.

[0026] Figure 6 A schematic diagram showing a general model of the second layer.

[0027] Figure 7 A schematic diagram showing a transmission window with a fixed window size per dynamic radio bearer (DRB) and a discard timer per protocol data unit (PDU) set is shown.

[0028] Figure 8 A schematic diagram is shown demonstrating updating of the transmission window and packet discarding based on expiration of the discard timer.

[0029] Fig. 9 A schematic diagram illustrating an example of packet discard based on failed PDU transmission is shown.

[0030] Fig.10 A schematic diagram illustrating an alternative approach to determining that all PDUs of a PDU set have been transmitted is shown.

[0031] Fig.11 is a block diagram of a wireless communication system according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0032] The embodiments of the present disclosure are described in detail with reference to the accompanying drawings in combination with the technical matters, structural features, implementation objectives and effects. Specifically, the terms in the embodiments of the present disclosure are only used for the purpose of describing the specific embodiments, and are not intended to limit the present disclosure. The abbreviations used in the description are listed below: Table 1

[0033] The present invention discloses a wireless communication method for processing extended reality (XR) traffic in an extended reality (XR) service. The XR service may include augmented reality (AR), virtual reality (VR) or mixed reality (MR).

[0034] In the description herein, a data packet may be a PDU or SDU of a protocol layer. For the sake of simplicity, the term "data packet" may refer to a PDU or an SDU, and the term "PDU" may refer to a PDU or an SDU.

[0035] In the description of this document, a dependent data unit is called a dependent data unit, and a data unit that depends on the dependent data unit is called a dependent data unit. For example, a dependent DRB is called a dependent DRB, and a DRB that depends on the dependent DRB is called a dependent DRB. Similarly, a dependent PDU set is called a dependent PDU set, and a PDU set that depends on the dependent PDU set is called a dependent PDU set. A dependent data packet is called a dependent data packet, and a data packet that depends on the dependent data packet is called a dependent data packet. A dependent QoS flow is called a dependent QoS flow, and a QoS flow that depends on the dependent QoS flow is called a dependent QoS flow. A dependent sub-QoS flow is called a dependent sub-QoS flow, and a sub-QoS flow that depends on the dependent sub-QoS flow is called a dependent sub-QoS flow.

[0036] As an enhancement to the current QoS framework to support XR services, 3GPP SA2 introduced a concept called “PDU Set” in the Technical Report (TR) 23.700-60.

[0037] A PDU set consists of one or more PDUs that carry the payload of an information unit generated at the application layer (e.g., a frame or video slice of an XR service, as used in TR 26.926). In some implementations, the application layer requires all PDUs in a PDU set to use the information unit. In other implementations, the application layer can recover part or all of the information unit when some PDUs are missing.

[0038] For XR traffic, such as one or more service traffic flows, a PDU set may be a group of packets or PDUs that are decoded or processed as a whole unit at the application layer. XR traffic has some potential dependencies between packets within a PDU set and / or between PDU sets. A service traffic flow for an XR service may include PDU sets of different types, importance levels, and QoS requirements.

[0039] Reference Figure 1 A telecommunication system including a user equipment (UE) 10a, a user equipment 10b, a base station (BS) 20a and a network entity device 30 performs the disclosed method according to an embodiment of the present disclosure. Figure 1For illustration only and not limitation, the system may include more UE, BS and CN entities. The connections between devices and device components are represented by lines and arrows in the figure. The user equipment 10a may include a processor 11a, a memory 12a and a transceiver 13a. The user equipment 10b may include a processor 11b, a memory 12b and a transceiver 13b. The base station 20a may include a processor 21a, a memory 22a and a transceiver 23a. The network entity device 30 may include a processor 31, a memory 32 and a transceiver 33. Each of the processors 11a, 11b, 21a and 31 may be configured to implement the functions, processes and / or methods proposed in the description. The layers of the wireless interface protocol may be implemented in the processors 11a, 11b, 21a and 31. Each of the memories 12a, 12b, 22a and 32 may be operable to store various programs and information to operate the connected processors. Each of the transceivers 13a, 13b, 23a and 33 is operably coupled to the connected processor to send and / or receive wireless signals or wired signals. The user equipment 10a can communicate with the user equipment 10b via a side link. The base station 20a can be one of an eNB, a gNB or other types of wireless nodes, and can configure wireless resources for the user equipment 10a and the user equipment 10b.

[0040] The network entity device 30 may be a node in a core network. The core network may include a Long Term Evolution (LTE) core network or a 5G Core (5G Core, 5GC), including a User Plane Function (UPF), a Session Management Function (SMF), a 5G Core Access and Mobility Management Function (AMF), a Unified Data Management (UDM), a Policy Control Function (PCF), a Control Plane (CP) / User Plane (UP) Separation (CUPS), an Authentication Server (AUSF), a Network Slice Selection Function (NSSF) and the Network Exposure Function (NEF).

[0041] The example of the user equipment in the description may include one of the user equipment 10a or the user equipment 10b. The example of the base station in the description may include the base station 20a. The transmission of an uplink (UL) control signal or data may be a transmission operation from the user equipment to the base station. The transmission of a downlink (DL) control signal or data may be a transmission operation from the base station to the user equipment. The downlink control signal may include a downlink control information (DCI) or a radio resource control (RRC) signal from the base station to the user equipment.

[0042] Figure 2 It is a transmission network model of XR services supported by the 5G system. The user equipment (UE) 10 is a 5G terminal that supports XR services and XR applications, and can be called a client, a client terminal, or an XR client. The gNB 20 is a 5G wireless node. The gNB 20 communicates with the UE 10 and provides NR user plane and control plane protocol termination to the UE through the NR Uu interface. The gNB 20 is connected to the 5G core network (5GC) 300 through the NG interface. The user plane function (User Plane Function, UPF) 30b is a UPF in the 5GC 300, that is, the 5G core network. The data network (Data Network, DN) 40 is a data network in which an XR server 41 providing XR services is located. The DN 40 can provide network operator services, Internet access, or third-party services. The XR server 41 may include a processor 411, a memory 412, and a transceiver 413. The processor 411 may be configured to implement the XR service-related functions, processes, and / or methods described in the description. The layers of the wireless interface protocol may be implemented in the processor 411. The memory 412 may be operable to store various programs and information to operate the connected processor. The transceiver 413 may be operably coupled to the connected processor to send and / or receive wireless signals or wired signals.

[0043] Each of the processors 411, 11a, 11b, 21a and 31 may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits and / or data processing devices. Each of the memories 412, 12a, 12b, 22a and 32 may include a read-only memory (ROM), a random access memory (RAM), a flash memory, a memory card, a storage medium and / or other storage devices. Each of the transceivers 413, 13a, 13b, 23a and 33 may include a baseband circuit and a radio frequency (RF) circuit to process radio frequency signals. When the embodiments are implemented in software, the techniques described herein may be implemented with modules, processes, functions, entities, etc. that perform the functions described herein. The modules may be stored in a memory and executed by the processor. The memory may be implemented inside the processor or outside the processor, in which case they may be communicatively coupled to the processor in various ways known in the art. The device that performs the wireless communication method may be a sending device that transmits an XR traffic stream of an XR service to a receiving device, or a receiving device that receives the XR traffic stream. The XR traffic stream may include one or more service traffic streams of the XR service. For example, the device that performs the wireless communication method may include the gNB 20, an XR server 41 in the data network 40, or a UE. That is, the XR server 41 in the data network 40 may operate as a sending device that performs the wireless communication method in certain XR traffic transmission occasions, and one or more XR clients (for example, one or more of the UE 10, UE 10a, and UE 10b) receive the XR traffic stream sent from the sending device as the receiving device. Similarly, an XR client (for example, one or more of the UE 10, UE 10a, and UE 10b) may operate as a sending device that performs the wireless communication method in certain XR traffic transmission occasions, and another XR client or the XR server 41 receives the XR traffic stream sent from the sending device as the receiving device. Alternatively, the sending device may include an intermediate device between the UE 10 and the XR server 41. The UE 10 may include an embodiment of the UE 10a or UE 10b. The gNB 20 may include an embodiment of the base station 20a. It should be noted that although the gNB 20 and UPF / 5GC 30b are described as an example in the description of this document, the wireless communication method may be performed by a base station, such as another gNB, an eNB, a base station integrating an eNB and a gNB, or a base station for technologies above 5G.The UPF / 5GC 30b may include another network entity of the 5GC.

[0044] A service traffic flow 5, such as an XR flow of an XR service, is established between the UE 10 and the XR server 41. The flow 5 includes a traffic flow 51 from the XR server 41 to the UE 10 and a traffic flow 52 from the UE 10 to the XR server 41.

[0045] In the description herein, a layer, such as an application layer, a PDCP layer, an RLC layer, a MAC layer, or a physical layer (PHY layer or L1 layer), may be a protocol layer entity in a transmitting device or a receiving device. The protocol layer entity may be implemented by a program or software module executed by a processor, or by a hardware module in an integrated circuit (IC).

[0046] Reference Figure 3 , an example of the sending device is shown as a sending device 10c, and an example of the receiving device is shown as a receiving device 10d. The sending device 10c includes a physical layer (PHY layer or L1 layer) 14c, a MAC layer 15c, an RLC layer 16c, a PDCP layer 17c, an RRC layer 18c, and an application layer 19c. The receiving device 10d includes a physical layer (PHY layer or L1 layer) 14d, a MAC layer 15d, an RLC layer 16d, a PDCP layer 17d, an RRC layer 18d, and an application layer 19d. For example, when the application layer 19c of the sending device 10c sends a PDU to the application layer 19d of the receiving device 10d through a lower layer (i.e., the PDCP layer 17c, the RLC layer 16c, the MAC layer 15c, and the physical layer 14c), the layer in the sending device 10c acts as a sending protocol layer entity on the sending side, and the layer in the receiving device 10d acts as a receiving protocol layer entity on the receiving side. The embodiments of the present disclosure may be implemented in the PDCP layer or the RLC layer. One or more steps (or blocks) in the embodiments of the present disclosure may be implemented as a computer program, instruction, software module stored in the memory of the transmitting device, or a circuit or hardware module in the processor of the transmitting device, or an IC chip, circuit or plug-in of the transmitting device.

[0047] The video stream of the XR service will be quasi-periodically encoded and compressed in the form of frames, each of which has a frame period of 1 / 60, 1 / 90 or 1 / 120 seconds. Since the sending device can divide the video stream of the XR service into multiple transmission units, encapsulate and transmit each of the transmission units into a transmission data packet across the network, the transmission mechanism of the XR service is actually based on data packets rather than frames. The size of each data packet can be variable, the number of data packets can be variable, and can be configured according to the QoS requirements and one or more parameters of the XR service characteristics, such as packet delay budget (PDB), packet error rate (PER), packet loss rate (PLR), frame error rate, frame delay budget, resolution, frame rate and / or data rate.

[0048] Reference Figure 4 and Figure 5 , a transmitting device (e.g., the UE 10 or the gNB 20) performs an embodiment of the disclosed method and initiates an XR service. In the transmitting device, protocol layer data is transmitted from a protocol layer entity to a lower layer according to a discard timer of a protocol data unit (PDU) set and a transmission window spanning multiple PDU sets. PDU (B101) of the PDU set of the service. B101 further includes Figure 5 The steps described in .

[0049] Reference Figure 5 The protocol layer entity starts the discard timer of the PDU set when receiving the first service data unit (SDU) associated with the PDU set from the higher layer (C101). The protocol layer entity receives the subsequent SDU from the higher layer (C102), and determines whether the PDU set sequence number (SN) of the PDU set associated with the subsequent SDU is less than the minimum PDU set SN of the transmission window (C103).

[0050] When the protocol layer entity receives a subsequent service data unit (SDU) from the higher layer and the PDU set sequence number (SN) of the PDU set associated with the subsequent SDU is less than the minimum PDU set SN of the transmission window, the protocol layer entity discards the subsequent SDU associated with the PDU set (C104). When the PDU set SN associated with the subsequent SDU is not less than the minimum PDU set SN of the transmission window and the subsequent SDU is not discarded, the protocol layer entity generates a PDU from the subsequent SDU for transmission to the lower layer (C105).

[0051] The protocol layer entity stops the discard timer (C106) when receiving and transmitting all the PDUs of the PDU set to the lower layer. When the discard timer of the PDU set times out, the protocol layer entity discards all the PDUs of the PDU set and stops the discard timer (C107). In one embodiment, one or more of the following parameters are configured for the PDU set: ●The number of data packets in the PDU set; ● an indicator indicating the first PDU of the PDU set; ● an indicator indicating the last PDU of the PDU set; ● one or more of said SNs depending on a PDU set in one or more DRBs depending on said PDU set; ● One or more DRB identifiers (IDs) of the dependent PDU set between one or more DRBs that depend on the PDU set.

[0052] In one embodiment, the transmission window includes parameters of a minimum PDU set SN and a maximum PDU set SN.

[0053] In an embodiment with a dynamic window size or a fixed window size, when the PDU set SN associated with the newly arrived SDU is greater than the maximum PDU set SN of the transmission window, the protocol layer entity sets the value of the maximum PDU set SN to the PDU set SN associated with the newly arrived SDU of the PDU set received by the protocol layer entity from the higher layer, and starts a new discard timer for the PDU set. The protocol layer entity generates a PDU from the newly arrived SDU for transmission to the lower layer.

[0054] In one embodiment, when all PDUs of the PDU set have been transmitted to the lower layer and the PDU set SN of the PDU set is equal to the minimum PDU set SN of the transmission window, the protocol layer entity sets the value of the minimum PDU set SN to the PDU set SN of the next PDU set of which at least one PDU has not yet been transmitted to the lower layer.

[0055] In one embodiment, the transmission window includes parameters of a minimum PDU set SN and a window size.

[0056] When the PDU set SN associated with the subsequent SDU is greater than the maximum PDU set SN of the transmission window, the protocol layer entity discards the subsequent SDU. When all the PDUs of the PDU set have been transmitted to the lower layer and the PDU set SN of the PDU set is equal to the minimum PDU set SN of the transmission window, the protocol layer entity sets the value of the minimum PDU set SN to the PDU set SN of the next PDU set of which at least one PDU has not been transmitted to the lower layer, and sets the value of the maximum PDU set SN to the minimum PDU set SN plus the window size.

[0057] In one embodiment, the transmission window includes parameters of a maximum PDU set SN and a window size.

[0058] When the PDU set SN associated with the newly arrived SDU is greater than the maximum PDU set SN of the transmission window, the protocol layer entity sets the value of the maximum PDU set SN to the PDU set SN associated with the newly arrived SDU of the PDU set received by the protocol layer entity from the higher layer, and starts a new discard timer for the PDU set. The protocol layer entity sets the value of the minimum PDU set SN to the maximum PDU set SN minus the window size. The protocol layer entity generates a PDU from the newly arrived SDU for transmission to the lower layer. The protocol layer entity discards all the SDUs associated with the PDU set SN that are less than the minimum PDU set SN.

[0059] In some embodiments, the transmission window is configured for a first dynamic radio bearer (DRB).

[0060] According to the intra-PDU set dependency, when the discard timer of the PDU set expires and indicates that at least one dependent PDU in the PDU set is discarded, the protocol layer entity discards all the PDUs in the PDU set. The protocol layer entity updates the transmission window of the first DRB.

[0061] According to the intra-DRB dependency, when the discard timer of the PDU set expires, the protocol layer entity discards all PDUs of a first dependent PDU set in the first DRB, and the first dependent PDU set depends on the PDU set in the same DRB. The protocol layer entity stops the discard timer of the first dependent PDU set. The protocol layer entity updates the transmission window of the first DRB.

[0062] According to the inter-DRB dependency, when the discard timer of the PDU set expires, the protocol layer entity discards all PDUs of the second dependent PDU set in the second DRB, and all PDUs of the second dependent PDU set are inter-DRB dependent on the PDU set in the first DRB. The protocol layer entity stops the discard timer of the second dependent PDU set. The protocol layer entity updates the transmission window of the first DRB and the transmission window of the second DRB.

[0063] In one embodiment, the protocol layer entity determines that all SDUs of the PDU set have been received by the protocol layer entity and all PDUs of the PDU set have been transmitted to the lower layer by the protocol layer entity based on the number of PDUs of the PDU set or an indicator indicating the last PDU of the PDU set.

[0064] In one embodiment, the transmitting device is a base station. The number of PDUs of the PDU set is provided by a 5G core (5GC) via an NG application protocol (NGAP) message or a general packet radio service tunneling protocol-user plane (GTP-U) PDU. An indicator indicating the last PDU of the PDU set is received from the 5GC via an NGAP message or a GTP-U PDU.

[0065] In one embodiment, the transmitting device is a user equipment (UE). The number of PDUs in the PDU set is provided by an application layer of the UE. An indicator indicating the last PDU in the PDU set is provided by the application layer of the UE.

[0066] In one embodiment, the sending device is a base station. The period of the discard timer is configured by the 5G core (5GC) through an NG application protocol (NGAP) message or a general packet radio service tunneling protocol-user plane (GTP-U) PDU.

[0067] In one embodiment, the sending device is a user equipment (UE). The timing period of the discard timer is configured by a base station through a radio resource control (RRC) message, or by an application of the UE.

[0068] In B101, the PDUs of the PDU set are transmitted from the protocol layer entity to the lower layer in the order of the PDU set SNs, or the PDUs of the PDU set are transmitted from the protocol layer entity to the lower layer in the order of the arrival times of the PDUs.

[0069] Figure 6It is a general model of the second layer responsible for the data transmission. According to the latest specifications of 3GPP TS38.321v17.1.0 (Media Access Control (MAC)), 3GPP TS 38.321v17.1.0 (Radio Link Layer (RLC)) and 3GPP TS38.321v17.1.0 (Packet Data Convergence Protocol (PDCP)), and considering that XR is a real-time and interactive service, the unacknowledged mode (UM) of RLC is more suitable for XR service, a method for detecting the failed transmission on the sending side is disclosed in the following.

[0069] Figure 6 It is a general model of the second layer responsible for the data transmission. According to the latest specifications of 3GPP TS 38.321v17.1.0 (Media Access Control (MAC)), 3GPP TS 38.321v17.1.0 (Radio Link Layer (RLC)) and 3GPP TS38.321v17.1.0 (Packet Data Convergence Protocol (PDCP)), and considering that XR is a real-time and interactive service, the unacknowledged mode (UM) of RLC is more suitable for XR service, a method for detecting the failed transmission on the sending side is disclosed in the following.

[0070] For hybrid automatic repeat request (HARQ) operation in MAC, each HARQ process supports one transport block (TB), and each HARQ process is associated with a HARQ process identifier. According to the HARQ operation principle, if the transmission fails, a TB can be transmitted or retransmitted multiple times. When the TB is successfully transmitted, the maximum number of retransmissions is reached, or the timer of the TB transmission expires, the transmission or retransmission of the TB can be terminated. The maximum number of retransmissions and the duration of the timer can be configurable or predefined.

[0071] When the transmission or retransmission is unsuccessful and is terminated due to reaching a maximum number of retransmissions or the timer of the TB transmission expiring, the transmission of the TB may be regarded as a failed transmission.

[0072] As a service provided by MAC, the MAC should report the status information of the data transmission service to a higher layer (eg, the RLC layer). As an embodiment, the status information may include an indication of successful or unsuccessful transmission of the RLC PDU.

[0073] In addition, RLC can interpret the status information from MAC as status information of data transmission services provided by RLC to the higher layer (e.g., the PDCP layer), especially for the UM data transmission service. As an embodiment, RLC can include an indication of successful or unsuccessful transmission of PDCP PDU to PDCP.

[0074] Packet transmission and drop:

[0075] For the packet discard based on the PDU set dependency, the PDU set may include multiple packets. The following discloses a method for PDU transmission to a lower layer based on the PDU set and the dependency configuration for a dynamic radio bearer (DRB).

[0076] The transmission window or buffer queue is defined based on a PDU set, a sequence number (SN) of the PDU set, a data packet associated with the PDU set, and a PDU of a protocol layer associated with the PDU set of the DRB. The window or queue may be defined by one or more parameters in the set {minimum PDU set, minimum PDU set SN, window size based on PDU set, maximum PDU set, maximum PDU set SN}.

[0077] As an embodiment, the transmission window or buffer queue is defined based on PDCP PDU, each PDCP PDU belongs to a PDU set, and each PDU set may include multiple PDCP PDUs. Each PDCP PDU is associated with the SN of the PDU set to which the PDCP PDU belongs. In particular, if PDCP supports segmentation, each PDCP PDU should only include segments of SDUs belonging to the same PDU set.

[0078] As an embodiment, the transmission window or buffer queue is defined based on RLC PDUs, each RLC PDU belongs to a PDU set, and each PDU set may include multiple RLC PDUs. Each RLC PDU is associated with the SN of the PDU set to which the RLC PDU belongs. In particular, if RLC supports segmentation, each RLC PDU should only include segments of SDUs belonging to the same PDU set.

[0079] The size of the window or queue is configured and fixed: the window is defined based on a minimum PDU set SN and a window size. The window size may be configurable and configured when the PDCP or RLC entity is established or reestablished for the DRB. The window size may be configured based on one or more characteristic parameters of the PDU set of the DRB. For the gNB side, the characteristic parameters may include periodicity, packet jitter information, delay budget, packet size, number of packets, which may be configured by the 5GC via NG Application Protocol (NGAP) messages. For the UE side, the window size may be configured by the gNB via Radio Resource Control (RRC) messages.

[0080] The size of the window or queue is variable. The window is defined based on a minimum PDU set SN. The size may vary as the SN of a newly arrived PDU changes.

[0081] A discard timer is associated with each PDU set per DRB.

[0082] As an embodiment, when a layer (eg, MAC, RLC or PDCP) receives a new SDU with a new PDU set SN from a higher layer, a new discard timer is started and associated with the SN of the PDU set.

[0083] For the gNB side, the 5GC (e.g., 5GC 30) may configure the same value for the expiration period of the discard timer for all PDU sets of a DRB through an NGAP message. For the UE side, the gNB (e.g., gNB 20) may configure the same value for the expiration period of the discard timer for all PDU sets of a DRB through an RRC message.

[0084] For the gNB side, the 5GC may configure the expiration period of the discard timer for a PDU set of a DRB through a GTP-U PDU, which is used to transmit the data packets of the PDU set from the 5GC to the gNB. For the UE side, the application (i.e., the application layer or application layer entity) in the UE may configure the expiration period of the discard timer for a PDU set of a DRB.

[0085] The discard timer is associated with a PDU set and is configured with an expiration period. When the first SDU associated with the PDU set is received, the discard timer of the PDU set is started.

[0086] The protocol layer entity of the sending device (eg, the PDCP, RLC or MAC layer) performs data packet discarding of the PDU set in response to expiration of the discard timer of the PDU set.

[0087] When all the PDUs of the PDU set are received and transmitted to the lower layer, the protocol layer entity stops the discard timer of the PDU set.

[0088] One or more of the following parameters are configured for the DRB to which the PDU set belongs:

[0089] Inter-DRB dependency configuration: The information (or configuration) of the inter-DRB dependency includes the DRB identifier (ID) of a DRB on which a DRB depends, and / or the processing method of the dependency. The dependent DRB is called a dependent DRB, and the DRB that depends on the dependent DRB is called a dependent DRB. For example, according to the inter-DRB dependency configuration, if a PDU set is lost or discarded, the processing method of the inter-DRB dependency indicates whether to discard the unsent PDUs of one or more other PDU sets that depend on the lost or discarded PDU set in the "Inter-DRB dependent DRB", and the lost or discarded PDU set is located in the "Inter-DRB depended DRB".

[0090] Intra-DRB dependency configuration: The intra-DRB dependency configuration indicates whether a PDU set in a DRB depends on another PDU set in the same DRB, and / or how the dependency is handled. The information (or configuration) of intra-DRB dependency may include a PDU set identifier (ID) of a PDU set on which a PDU set depends, and / or how the dependency is handled. The dependent PDU set is called a dependent PDU set, and the PDU set that depends on the dependent PDU set is called a dependent PDU set. The dependent PDU set and the dependent PDU set are located in the same DRB. For example, if a PDU set is lost or discarded, the handling method (or configuration) of the intra-DRB dependency indicates whether to discard the unsent PDUs of the dependent PDU set in the same DRB that depends on the lost or discarded PDU set within the DRB.

[0091] The intra-PDU set dependency configuration: The intra-PDU set dependency configuration indicates whether one or more data packets (e.g., PDUs) belonging to one or more PDU sets are dependent on a data packet in the same PDU set, and how the dependency is handled. The information (or configuration) of the intra-PDU set dependency may include a PDU identifier (ID) on which another PDU depends, and / or how the dependency is handled. The dependent PDU is called a dependent PDU, and the PDU that depends on the dependent PDU is called a dependent PDU. The dependent PDU and the dependent PDU are located in the same PDU set. For example, the way the intra-PDU set dependency is handled indicates whether to discard an unsent dependent PDU in the same PDU set if a dependent PDU is lost or discarded.

[0092] Configure one or more of the following parameters for each PDU set: ●The number of data packets in the PDU set. ● An indicator indicating the first data packet or PDU of the PDU set. • An indicator indicating the last data packet or PDU of the PDU set. ●One or more of the SNs of one or more “intra-DRB dependent PDU sets” that depend on the PDU set, wherein the parameters may include the explicit SNs of the one or more “intra-DRB dependent PDU sets”, or the number of consecutive PDU sets following the PDU set. ●One or more SN and DRB ID combinations of one or more "inter-DRB dependent PDU sets" that depend on the PDU set.

[0093] like Figure 7 and Figure 8 As shown, three DRBs are configured for the XR service, t represents the axis in the time domain, and the variables n and x are positive integers. The three DRBs can be further configured as a DRB group. The DRB 1 is independent, the DRB 2 depends on the DRB 1 between DRBs, and the DRB 3 depends on DRB 1 and DRB 2 between DRBs. The DRB 2 is configured with intra-DRB dependency. Both DRB 2 and DRB 3 are configured with intra-PDU set dependency. The dependency handling mode can be configured as a "discard" value.

[0094] Basically, a window or queue is defined for each DRB, and the minimum PDU set SN of the window or queue is named Minimum_PDU_Set_SN and should be set to 0 when the DRB is established or reestablished. A discard timer is named discard_timer(n) for the PDU set SNn and should be started and configured with an expiration period for the PDU set. In the following description, a window is taken as an example.

[0095] Window operations with variable window size:

[0096] like Figure 8 As shown, a window is defined for each DRB, and the window size is variable. The Minimum_PDU_Set_SN is used as a reference, and an additional parameter Maximum_PDU_Set_SN is used to record the SN equal to the maximum SN of the newly arrived SDU plus 1. For each SDU of a DRB received from a higher layer, the SN of the SDU is associated with the SN of the PDU set and is expressed as PDU_Set_SN(SDU). (Note that the following SN comparison should take into account the wraparound of the PDU set SN) ● If PDU_Set_SN(SDU) < Minimum_PDU_Set_SN ■ Discard the SDU ● Otherwise if Minimum_PDU_Set_SN <= PDU_Set_SN(SDU) <= Maximum_PDU_Set_SN ■ Store the SDU in the transmission buffer for transmission ● Otherwise PDU_Set_SN(SDU) > Maximum_PDU_Set_SN ■ Set Maximum_PDU_Set_SN = PDU_Set_SN(SDU) ■ Start a discard timer for the new PDU set (SN = Maximum_PDU_Set_SN) ■ Store the SDU in the transmission buffer for transmission ● If all the PDUs of a PDU set have been transmitted or discarded ■ Stop the discard timer for the PDU set ■ If the SN of the PDU set = Minimum_PDU_Set_SN ◆ Set Minimum_PDU_Set_SN to the next PDU set with at least one PDU not sent

[0097] Window operation with configured window size in Case 1:

[0098] As Fig. 9 shown, a window is defined for each DRB, and the window size is configured as a static value. The Minimum_PDU_Set_SN is used as a reference, and the Maximum_PDU_Set_SN of the window is equal to Minimum_PDU_Set_SN plus the window size. For each SDU of each DRB received from the higher layer, the SN (represented in pseudocode) related to the SDU in the following operations is the SN of the PDU set PDU_Set_SN(SDU), which is equal to the SN of the related PDU set. (Note that the following SN comparisons should consider the wrap-around of the PDU set SN) ● If PDU_Set_SN(SDU) < Minimum_PDU_Set_SN or PDU_Set_SN(SDU) > Maximum_PDU_Set_SN ■ Discard the SDU ● Otherwise, Minimum_PDU_Set_SN <= PDU_Set_SN(SDU) <= Maximum_PDU_Set_SN ■ Store the SDU in the receive buffer for transmission ● If all the PDUs of a PDU set have been transmitted or discarded ■ Stop the discard timer for the PDU set ■ If the SN of the PDU set = Minimum_PDU_Set_SN ◆ Set Minimum_PDU_Set_SN to the next PDU set that has at least one PDU not sent ◆ Maximum_PDU_Set_SN = Minimum_PDU_Set_SN + window size

[0099] Configure window operations in case 2 of the window size:

[0100] As Figure 7 shown, a window is defined for each DRB, and the window size is configured as a static value. Variables n and x are integers. The Maximum_PDU_Set_SN is used as a reference, and the Minimum_PDU_Set_SN for the window is equal to Maximum_PDU_Set_SN minus the window size. For each SDU of a DRB received from the higher layer, the SN of the PDU set associated with the SDU is PDU_Set_SN(SDU). (Note that the following SN comparison should consider the PDU set SN wrap-around) ● If PDU_Set_SN(SDU) > Maximum_PDU_Set_SN ■ Set the Maximum_PDU_Set_SN to PDU_Set_SN(SDU) ■ Set the Minimum_PDU_Set_SN = Maximum_PDU_Set_SN - window size ■ Discard the PDUs associated with the PDU set (SN < Minimum_PDU_Set_SN) ● Otherwise if PDU_Set_SN(SDU) < Minimum_PDU_Set_SN ■ Discard the SDU ● Otherwise, Minimum_PDU_Set_SN <= PDU_Set_SN(SDU) <= Maximum_PDU_Set_SN ■ Store the SDU in the receive buffer for transmission ● If all the PDUs in a PDU set are transmitted or discarded ■ Stop the discard timer for the PDU set

[0101] Packet discard based on expiration of the discard timer:

[0102] like Figure 8 As shown, where variables k, m and n are positive integers, if the discard_timer (k) of the PDU set (SN = k) expires, the following data packet discard and the operations related to the discard timer and the window are triggered: ● discard the unsent data PDUs of the PDU set (SN=k) in DRB 1; ■ Stop the discard_timer(k) of the PDU set (SN=k) ■Minimum_PDU_Set_SN of DRB 1 = k+1 ● Since the PDU set (SN=m) in DRB 2 depends on the PDU set (SN=k) in DRB 1 between DRBs, the unsent data PDUs of the PDU set (SN=m) in DRB 2 are discarded; ■ Stop the discard_timer(m) of the PDU set (SN=m) ■Minimum_PDU_Set_SN of DRB 2 = m+1 ● Since the PDU set (SN=n+1) in DRB 3 depends on the PDU set (SN=m) in DRB 2 between DRBs, the unsent data PDUs of the PDU set (SN=n+1) in DRB 3 are discarded; ■ Stop the discard_timer (n+1) of the PDU set (SN=n+1) ● Since the PDU set (SN=n) in DRB 3 depends on the PDU set (SN=k) in DRB 1 between DRBs, the unsent data PDUs of the PDU set (SN=n) in DRB 3 are discarded; ■ Stop the discard_timer(n) of the PDU set (SN=n) ■Minimum_PDU_Set_SN for DRB 3 = n+2

[0103] Packet discard based on failed PDU transmission:

[0104] like Fig. 9As shown, if a PDU in the PDU set (SN=m) fails to be transmitted, the following packet discarding and the operations related to the discarding timer and the window are triggered: ● Since DRB 2 is configured with intra-PDU set dependency, the unsent data PDUs of the PDU set (SN=m) in DRB 2 are discarded; ■ Stop the discard_timer(m) of the PDU set (SN=m) ■Minimum_PDU_Set_SN of DRB 2 = m+1 ● Since the PDU set (SN=m+1) depends on the PDU set (SN=m) between DRBs, the unsent data PDUs of the PDU set (SN=m+1) in DRB 2 are discarded; ■ Stop the discard_timer (m+1) of the PDU set (SN=m+1) ■Minimum_PDU_Set_SN of DRB 2 = m+1 ● Since the PDU set (SN=n+1) in DRB 3 depends on the PDU set (SN=m) in DRB 2 between DRBs, the unsent data PDUs of the PDU set (SN=n+1) in DRB 3 are discarded; ■ Stop the discard_timer (n+1) of the PDU set (SN=n+1) ● Since the PDU set (SN=n+2) in DRB 3 depends on the PDU set (SN=m+1) in DRB 2 between DRBs, the unsent data PDUs of the PDU set (SN=n+2) in DRB 3 are discarded; ■ Stop the discard_timer (n+2) of the PDU set (SN=n+2)

[0105] Normal PDU transmission of a PDU set:

[0106] For normal PDU transmission, the following details the basic normal transmission process for a set of PDUs for a DRB to the lower layers:

[0107] When the first SDU associated with the PDU set is received, a discard timer is started and an expiration period is configured and associated with the PDU set.

[0108] Receives SDUs from higher layers and transmits PDUs (generated from the received SDUs) to lower layers unless packet discard occurs due to expiration of a discard timer or PDU transmission failure.

[0109] When all the PDUs of the PDU set are received and transmitted to the lower layers:

[0110] stopping the discard timer of the PDU set;

[0111] The window is adjusted accordingly and the Minimum_PDU_Set_SN is updated to the next PDU set with at least one PDU not sent.

[0112] To determine that all PDUs of a PDU set have been received and transmitted to lower layers, two schemes are detailed below:

[0113] Solution 1: For the gNB side, the number of PDUs of the PDU set is provided by the 5GC through an NGAP message or a GTP-UPDU. For the UE side, the number of PDUs of the PDU set is provided by the application layer. When the number of PDUs received and transmitted is equal to the number of PDUs provided for a PDU set, the protocol layer entity of the transmitting device (e.g., the gNB or the UE) can determine that all the PDUs of the PDU set have been received and transmitted to a lower layer. In this case, the reception and transmission of the PDUs of the PDU set can be unordered or ordered.

[0114] Solution 2: For the gNB side, the indicator indicating the last PDU of the PDU set is received from the 5GC through an NGAP message or a GTP-U PDU; for the UE side, the indicator indicating the last PDU of the PDU set is provided by the application layer. In this case, the reception and transmission of the PDUs of the PDU set can be in order.

[0115] As an embodiment, the PDUs of different PDU sets for a DRB should be transmitted to the lower layer in the order of the PDU sets. That is, all the PDUs of the PDU set (SN=n) should be transmitted before any PDU of the PDU set (SN=n+1). In this case, the corresponding protocol layer should support the function of buffering the arriving PDUs in advance.

[0116] As an embodiment, PDUs of different PDU sets for one DRB may be transmitted to the lower layer in the order of arrival time without considering the SN order of the different PDU sets.

[0117] like Fig.10 As shown, the variables n, k, x, y and z are positive integers.

[0118] For DRB 1, the number of PDUs of each PDU set is provided as PDU_number(k), so when the number of PDUs received and transmitted is equal to the PDU_number(k), that is, the number of received PDUs = PDU_number(k), the protocol layer entity of the sending device (e.g., the gNB or the UE) can determine that all the PDUs of the PDU set (SN=k) have been received and transmitted to the lower layer.

[0119] For DRB 2 / 3, when the indicator indicating the last PDU of the two PDU sets is received respectively, the protocol layer entity of the sending device (e.g., the gNB or the UE) can determine that all the PDUs of the PDU set (SN=n) and the PDU set (SN=m) have been received and transmitted to the lower layer.

[0120] Fig.11 7 is a block diagram of an exemplary system 700 for wireless communication according to an embodiment of the present disclosure. The embodiments described herein may be implemented into the system using any appropriately configured hardware and / or software. Fig.11 The system 700 is shown, including radio frequency (RF) circuitry 710, baseband circuitry 720, a processing unit 730, memory / storage 740, a display 750, a camera 760, a sensor 770, and an input / output (I / O) interface 780, which are coupled to each other as shown.

[0121] The processing unit 730 may include circuits such as, but not limited to, one or more single-core or multi-core processors. The processor may include any combination of general-purpose processors and special-purpose processors (e.g., graphics processors and application processors). The processor may be coupled to the memory / storage and configured to execute instructions stored in the memory / storage to support various applications and / or operating systems running on the system.

[0122] The radio control functions may include, but are not limited to, signal modulation, encoding, decoding, radio frequency shifting, etc. In some embodiments, the baseband circuit may support communication with one or more wireless technologies. For example, in some embodiments, the baseband circuit may support communication with 5G New Air (NR), LTE, Evolved Universal Terrestrial Radio Access Network (EUTRAN) and other wireless metropolitan area networks (WMAN), wireless local area network (WLAN), wireless personal area network (WPAN). An embodiment in which the baseband circuit is configured to support wireless communications of multiple wireless protocols may be referred to as a multi-mode baseband circuit. In various embodiments, the baseband circuit 720 may include circuits for processing signals that are not strictly regarded as baseband frequencies. For example, in some embodiments, the baseband circuit may include circuits for processing intermediate frequency signals between the baseband frequency and the radio frequency.

[0123] In various embodiments, the system 700 may be a mobile computing device, such as, but not limited to, a notebook computing device, a tablet computing device, a mini notebook, a netbook, a smart phone, etc. In various embodiments, the system may have more or fewer components and / or different architectures. Where appropriate, the methods described herein may be implemented as a computer program. The computer program may be stored on a storage medium, such as a non-transitory storage medium.

[0124] The described embodiments of the present disclosure may employ a combination of techniques / processes in 3GPP specifications to create a final product.

[0125] If the software functional unit is implemented as a product and used and sold, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution proposed in the present disclosure can be essentially or partially implemented in the form of a software product. Alternatively, a part of the technical solution that is beneficial to the prior art can be implemented in the form of a software product. The computer software product is stored in a storage medium and includes multiple instructions for enabling a computing device (such as a personal computer, a server, or a network device) to run all or part of the steps disclosed in the embodiments of the present disclosure. The storage medium includes a USB disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a floppy disk, or other medium capable of storing program code.

[0126] While the present disclosure has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements within the scope thereof without departing from the broadest interpretation of the appended claims.

Claims

1. A wireless communication method, which may be performed in a wireless communication device, wherein the wireless communication device operates as a transmitting device, the method comprising: transmitting a protocol data unit (PDU) set of the service from a protocol layer entity to a lower layer based on a discard timer for the PDU set and a transmission window spanning a plurality of PDU sets; When the protocol layer entity receives a first service data unit (SDU) associated with the PDU set from a higher layer, starting the discard timer of the PDU set; When the protocol layer entity receives a subsequent service data unit (SDU) from the higher layer and a PDU set sequence number (SN) of the PDU set associated with the subsequent SDU is less than a minimum PDU set SN of the transmission window, discard the subsequent SDU associated with the PDU set; when the PDU set SN associated with the subsequent SDU is not less than the minimum PDU set SN of the transmission window and the subsequent SDU is not discarded, generate a PDU from the subsequent SDU for transmission to the lower layer; When all the PDUs of the PDU set are received and transmitted to the lower layer, stopping the discard timer; When the discard timer of the PDU set times out, all PDUs of the PDU set are discarded And stop the discard timer.

2. The method of claim 1, wherein the PDU set is configured with one or more of the following parameters: the number of packets in the PDU set; an indicator indicating the first PDU of the PDU set; an indicator indicating the last PDU of the PDU set; one or more SNs of a dependent PDU set in one or more DRBs of the dependent PDU set; and One or more DRB identifiers (IDs) of the dependent PDU set between one or more DRBs that depend on the PDU set.

3. The method of claim 1, wherein the PDUs of the PDU set are transmitted from the protocol layer entity to the lower layer in the order of the PDU set SNs.

4. The method of claim 1, wherein the PDUs of the PDU set are transmitted from the protocol layer entity to a lower layer in order of arrival time of the PDUs.

5. The method of claim 1, wherein the transmission window comprises parameters of a minimum PDU set SN and a maximum PDU set SN.

6. The method of claim 5, wherein when the PDU set SN associated with the newly arrived SDU is greater than the maximum PDU set SN of the transmission window, the protocol layer entity sets the value of the maximum PDU set SN to the PDU set SN associated with the newly arrived SDU of the PDU set received by the protocol layer entity from the higher layer, and starts a new discard timer for the PDU set; and The protocol layer entity generates a PDU from the newly arrived SDU for transmission to the lower layer.

7. The method of claim 5, wherein when all PDUs of the PDU set have been transmitted to the lower layer and the PDU set SN of the PDU set is equal to the minimum PDU set SN of the transmission window, the protocol layer entity sets the value of the minimum PDU set SN to the PDU set SN of the next PDU set in which at least one PDU has not yet been transmitted to the lower layer.

8. The method of claim 1, wherein the transmission window comprises parameters of a minimum PDU set SN and a window size.

9. The method of claim 8, wherein when the PDU associated with the subsequent SDU When the set SN is greater than the maximum PDU set SN of the transmission window, the protocol layer entity discards the subsequent SDU; Wherein, when all the PDUs of the PDU set have been transmitted to the lower layer and the PDU set SN of the PDU set is equal to the minimum PDU set SN of the transmission window, the protocol layer entity sets the value of the minimum PDU set SN to the PDU set SN of the next PDU set of which at least one PDU has not been transmitted to the lower layer, and sets the value of the maximum PDU set SN to the minimum PDU set SN plus the window size.

10. The method of claim 1, wherein the transmission window comprises parameters of a maximum PDU set SN and a window size.

11. The method of claim 10, wherein when the PDU set SN associated with the newly arrived SDU is greater than the maximum PDU set SN of the transmission window, the protocol layer entity sets the value of the maximum PDU set SN to the PDU set SN associated with the newly arrived SDU of the PDU set received by the protocol layer entity from the higher layer, and starts a new discard timer for the PDU set; The protocol layer entity sets the value of the minimum PDU set SN to the maximum PDU set SN minus the window size; The protocol layer entity generates a PDU from the newly arrived SDU for transmission to the lower layer; and The protocol layer entity discards all SDUs associated with the PDU set SN that is smaller than the minimum PDU set SN.

12. The method of claim 1, wherein the transmission window is configured for a first dynamic radio bearer (DRB).

13. The method of claim 12, wherein, according to the intra-PDU set dependency, when the discard timer of the PDU set expires and indicates that at least one dependent PDU in the PDU set is discarded, the protocol layer entity discards all PDUs in the PDU set; and The protocol layer entity updates the transmission window of the first DRB.

14. The method of claim 12, wherein according to intra-DRB dependency, when the discard timer of the PDU set expires, the protocol layer entity discards all PDUs of a first dependent PDU set in the first DRB, the first dependent PDU set being dependent on the PDU set in the same DRB; The protocol layer entity stops a discard timer of the first dependent PDU set; and The protocol layer entity updates the transmission window of the first DRB.

15. The method of claim 12, wherein according to the inter-DRB dependency, when the discard timer of the PDU set expires, the protocol layer entity discards all PDUs of a second dependent PDU set in a second DRB, and all PDUs of the second dependent PDU set are inter-DRB dependent on the PDU set in the first DRB; The protocol layer entity stops a discard timer of the second dependent PDU set; and The protocol layer entity updates the transmission window of the first DRB and the transmission window of the second DRB.

16. The method of claim 1, wherein the protocol layer entity determines that all SDUs of the PDU set have been received by the protocol layer entity and all PDUs of the PDU set have been transmitted to the lower layer by the protocol layer entity based on the number of PDUs of the PDU set or an indicator indicating the last PDU of the PDU set.

17. The method of claim 16, wherein the transmitting device is a base station; wherein the number of PDUs in the PDU set is provided by the 5G Core (5GC) via an NG Application Protocol (NGAP) message or a General Packet Radio Service Tunneling Protocol-User Plane (GTP-U) PDU; and Wherein an indicator indicating the last PDU of the PDU set is received from the 5GC via an NGAP message or a GTP-U PDU.

18. The method of claim 16, wherein the transmitting device is a user equipment (UE); The number of PDUs in the PDU set is provided by the application layer of the UE; and The indicator indicating the last PDU of the PDU set is provided by the application layer of the UE.

19. The method of claim 1, wherein the transmitting device is a base station; The period of the discard timer is configured by the 5G core (5GC) through an NG application protocol (NGAP) message or a general packet radio service tunneling protocol-user plane (GTP-U) PDU.

20. The method of claim 1, wherein the transmitting device is a user equipment (UE); The timing period of the discard timer is configured by the base station through a radio resource control (RRC) message, or by an application of the UE.

21. A wireless communication device, comprising: A processor configured to call and run a computer program stored in a memory so that a device equipped with the processor executes the method according to any one of claims 1 to 20.

22. A chip, comprising: A processor configured to call and run a computer program stored in a memory so that a device equipped with the chip executes a method as claimed in any one of claims 1 to 20.

23. A computer-readable storage medium having a computer program stored therein, wherein the computer program causes a computer to execute the method according to any one of claims 1 to 20.

24. A computer program product comprising a computer program, wherein the computer program causes a computer to execute the method according to any one of claims 1 to 20.

25. A computer program, wherein the computer program causes a computer to execute the method according to any one of claims 1 to 20.

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