Wireless communication method and apparatus

Abstract

A method of wireless communication can be performed in a wireless communication device. The device transmits, from a protocol layer entity to a lower layer, protocol data units (PDUs) of a set of PDUs according to a discard timer of the set of PDUs and a transmission window spanning multiple sets of PDUs.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of telecommunications, in particular to a wireless communication method and device. BACKGROUND

[0002] Wireless communication systems, such as the third generation (3G) mobile telephone standards and technologies, are widely known. Such 3G standards and technologies are developed by the Third Generation Partnership Project (3GPP). Third generation wireless communication is generally developed to support macro cellular mobile telephone communication. The communication systems and networks have evolved into broadband and mobile systems. In a cellular wireless communication system, User Equipment (UE) connects to a Radio Access Network (RAN) through a wireless link. The RAN comprises a set of Base Stations (BS) that provide wireless links for the UEs located in the cells covered by the base stations and interfaces with a core network (CN) that provides overall network control. It can be appreciated that the RAN and CN each perform respective 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 Telecommunication 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 Node Bs). Recently, LTE is further evolved to the so-called 5G or New Radio (NR) system in which one or more cells are supported by base stations called gNBs.

[0003] TECHNICAL PROBLEM

[0004] 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 functionalities to support eMBB, URLLC and mMTC are introduced in Release 15 and enhanced in Release 16 and 17.

[0005] Extended reality (XR) is a general term that covers Augmented Reality (AR), Mixed Reality (MR), and Virtual Reality (VR). XR applications usually 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.

[0006] XR services are characterized by their special traffic flows with real-time, high data rates, and low latency. An XR video stream contains different frames / video slices. For example, a group of pictures (GOP) includes I / P / B frames. Certain special characteristics of such XR service flows should be considered and supported in 5G.

[0007] On one hand, the data size of different frames is different, and one frame can be split into a group of data packets. However, the application can only decode the frames / video slices when all the data packets of the frames / video slices are successfully received. A group of data packets (hereinafter referred to as a data packet group) belonging to one frame / video slice should be processed as a unit.

[0008] On the other hand, certain types of data packet groups can 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. That is, there is a dependency relationship between different data packet groups.

[0009] 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 groups of the XR service, the outdated data packets are 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:

[0010] • How to detect the failed transmission and discard the useless data packet group as soon as possible;

[0011] • How to discard the data packets according to the dependency between the data packets or other data units in the XR service. SUMMARY

[0012] The object of the present disclosure is to propose a wireless communication method and device.

[0013] In a first aspect, embodiments of the present application provide a wireless communication method, which can be executed in a wireless communication device as a transmitting device, and the method comprises:

[0014] transmitting, from a protocol layer entity, a protocol data unit (PDU) of a PDU set to a lower layer according to a discard timer of the PDU set and a transmission window spanning multiple PDU sets;

[0015] starting the discard timer of the PDU set when the protocol layer entity receives a first service data unit (SDU) associated with the PDU set from a higher layer;

[0016] discarding a subsequent service data unit (SDU) associated with the PDU set when the protocol layer entity receives the subsequent 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;

[0017] 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;

[0018] stopping the discard timer when all the PDUs of the PDU set are received and transmitted to the lower layer;

[0019] discarding all the PDUs of the PDU set when the discard timer of the PDU set expires

[0020] and stopping the discard timer.

[0021] In a second aspect, embodiments of the present disclosure provide a wireless communication device comprising a processor configured to invoke and execute a computer program stored in a memory to cause the device in which the processor is installed to perform the disclosed method.

[0022] The wireless communication device comprises a user equipment or a base station.

[0023] The disclosed method can be implemented in a chip. The chip can comprise a processor configured to invoke and execute a computer program stored in a memory to cause the device in which the chip is installed to perform the disclosed method.

[0024] The disclosed method can be programmed as computer executable instructions stored in a non-transitory computer readable medium. The non-transitory computer readable medium, when loaded into a computer, instructs a processor of the computer to perform the disclosed method.

[0025] The non-transitory computer readable medium can include at least one of a hard disk, a compact disc read only memory (CD-ROM), an optical storage device, a magnetic storage device, a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), and a flash memory.

[0026] The disclosed method can be programmed as a computer program product to make a computer execute the disclosed method.

[0027] The disclosed method can be programmed as a computer program to make a computer execute the disclosed method.

[0028] Advantages

[0029] One embodiment of the present disclosure provides a method, in which a transmitting device transmits a discard indication so that a receiving device can correctly handle a sequence number (SN) gap due to group PDU discard.

[0030] 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 DRAWINGS

[0031] In order to more clearly illustrate the embodiments or the related technology of the present disclosure, the accompanying drawings for describing the embodiments will be briefly introduced. Obviously, the drawings only illustrate some of the embodiments of the present disclosure, and a person of ordinary skill in the art can obtain other drawings from these drawings without paying any premise.

[0032] Figure 1 A schematic diagram of a telecommunications system is shown.

[0033] Figure 2 A schematic diagram of a network embodiment showing the disclosed wireless communication method is shown.

[0034] Figure 3 A schematic diagram of protocol layers of a transmitting device and a receiving device is shown.

[0035] Figure 4 A schematic diagram of a wireless communication method according to an embodiment of the present disclosure is shown.

[0036] Figure 5A schematic diagram of a wireless communication method according to embodiments of the disclosure is shown.

[0037] Figure 6 A schematic diagram of a general model of the second layer is shown.

[0038] Figure 7 A schematic diagram showing a transmission window with a fixed window size for each data radio bearer (DRB) and a discard timer for each protocol data unit (PDU) set is shown.

[0039] Figure 8 A schematic diagram showing an update of the transmission window and packet discard based on the discard timer expiring is shown.

[0040] Figure 9 A schematic diagram showing an example of packet discard based on a failed PDU transmission is shown.

[0041] Figure 10 A schematic diagram showing an optional solution to determine that all PDUs of a PDU set have been transmitted is shown.

[0042] Figure 11 is a block diagram of a wireless communication system according to embodiments of the disclosure. DETAILED DESCRIPTION

[0043] Embodiments of the disclosure are described in detail with reference to the accompanying drawings. Specifically, the terms in the embodiments of the disclosure are used only for the purpose of describing the specific embodiments, and are not intended to limit the disclosure.

[0044] Abbreviations used in the description are listed below:

[0045] Table 1

[0046]

[0047]

[0048] A wireless communication method for handling extended reality (XR) traffic in an extended reality (XR) service is disclosed. The XR service can include an augmented reality (AR), a virtual reality (VR), or a mixed reality (MR).

[0049] In the description herein, a data packet can be a PDU or a SDU of a protocol layer. For simplicity, the term “data packet” can refer to a PDU or a SDU, and the term “PDU” can refer to a PDU or a SDU.

[0050] In the description herein, a data unit that is depended on is referred to as a depended data unit, and a data unit that depends on the depended data unit is referred to as a dependent data unit. For example, a depended DRB is referred to as a depended DRB, and a DRB that depends on the depended DRB is referred to as a dependent DRB. Similarly, a depended PDU set is referred to as a depended PDU set, and a PDU set that depends on the depended PDU set is referred to as a dependent PDU set. A depended data packet is referred to as a depended data packet, and a data packet that depends on the depended data packet is referred to as a dependent data packet. A depended QoS flow is referred to as a depended QoS flow, and a QoS flow that depends on the depended QoS flow is referred to as a dependent QoS flow. A depended sub-QoS flow is referred to as a depended sub-QoS flow, and a sub-QoS flow that depends on the depended sub-QoS flow is referred to as a dependent sub-QoS flow.

[0051] As an enhancement of the current QoS framework to support XR services, 3GPP SA2 introduced a concept called “PDU Set” in the Technical Report (TR) 23.700-60.

[0052] 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 a video slice of an XR service, as used in TR 26.926). In some implementations, the application layer needs 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 certain PDUs are missing.

[0053] For XR traffic, e.g., one or more service traffic flows, a PDU Set can be a group of data packets or PDUs that are decoded or processed at the application layer as a whole unit. There are some potential dependencies between data packets within a PDU Set and / or between PDU Sets for XR traffic. A service traffic flow of an XR service can include PDU Sets of different types, importance levels, and QoS requirements.

[0054] Referring to Figure 1 A telecommunication system including a User Equipment (UE) 10a, a user equipment 10b, a Basestation (BS) 20a, and a network entity device 30 performs the disclosed methods according to embodiments of the present disclosure. Figure 1For illustration only and not limitation, the system can 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 can include a processor 11a, a memory 12a and a transceiver 13a. The user equipment 10b can include a processor 11b, a memory 12b and a transceiver 13b. The base station 20a can include a processor 21a, a memory 22a and a transceiver 23a. The network entity device 30 can include a processor 31, a memory 32 and a transceiver 33. Each of the processors 11a, 11b, 21a and 31 can be configured to implement the functions, procedures and / or methods described in the description. Layers of a radio interface protocol can be implemented in the processors 11a, 11b, 21a and 31. Each of the memories 12a, 12b, 22a and 32 is operable to store various programs and information for operating the connected processor. Each of the transceivers 13a, 13b, 23a and 33 is operably coupled with the connected processor to transmit and / or receive wireless signals or wired signals. The user equipment 10a can communicate with the user equipment 10b through a sidelink. The base station 20a can be one of an eNB, a gNB or other types of wireless nodes, and can configure radio resources for the user equipment 10a and user equipment 10b.

[0055] The network entity device 30 can be one node in a core network. The core network can include a Long Term Evolution (LTE) core network or a 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).

[0056] Examples of the user equipment in the description can include one of the user equipment 10a or user equipment 10b. Examples of the base station in the description can include the base station 20a. The transmission of uplink (UL) control signals or data can be a transmission operation from the user equipment to the base station. The transmission of downlink (DL) control signals or data can be a transmission operation from the base station to the user equipment. The downlink control signals can include downlink control information (DCI) or radio resource control (RRC) signals from the base station to the user equipment.

[0057] Figure 2 is a transmission network model of an XR service supported by a 5G system. The user equipment (UE) 10 is a 5G terminal supporting an XR service and an XR application, which can be referred to as a client, a client terminal, or an XR client. The gNB 20 is a 5G radio node. The gNB 20 communicates with the UE 10 and provides NR user plane and control plane protocol terminations to the UE through an NR Uu interface. The gNB 20 is connected to a 5G core network (5GC) 300 through an NG interface. The user plane function (UPF) 30b is a UPF in the 5GC 300, i.e., a 5G core network. The data network (DN) 40 is a data network in which an XR server 41 providing an XR service is located. The DN 40 can provide a network operator service, Internet access, or a third party service. The XR server 41 can include a processor 411, a memory 412, and a transceiver 413. The processor 411 can be configured to implement the XR service related functions, procedures, and / or methods described in the description. Layers of a radio interface protocol can be implemented in the processor 411. The memory 412 is operatively configured to store various programs and information for operating the connected processor. The transceiver 413 is operatively coupled with the connected processor, and transmits and / or receives a wireless signal or a wired signal.

[0058] Each of the processors 411, 11a, 11b, 21a, and 31 can include an application-specific integrated circuit (ASIC), other chip sets, logic circuit, and / or a data processing device. Each of the memories 412, 12a, 12b, 22a, and 32 can 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 can 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 can be implemented with modules, procedures, functions, entities, etc. that perform the functions described herein. The modules can be stored in the memories and executed by the processors. The memories can be implemented within the processors or implemented outside the processors in which case they can be communicatively coupled to the processors via various means as is known in the art. The devices performing the wireless communication methods can be a transmitting device transmitting an XR traffic flow of an XR service to a receiving device, or a receiving device receiving the XR traffic flow. The XR traffic flow can include one or more service traffic flows of the XR service. For example, the devices performing the wireless communication methods can include the gNB 20, an XR server 41 in a data network 40, or a UE. That is, the XR server 41 in the data network 40 can operate as a transmitting device performing a wireless communication method in certain XR traffic transmission scenarios, while one or more XR clients (e.g., one or more of the UEs 10, 10a, and 10b) operate as the receiving device receiving the XR traffic flow transmitted from the transmitting device. Similarly, one XR client (e.g., one or more of the UEs 10, 10a, and 10b) can operate as a transmitting device performing a wireless communication method in certain XR traffic transmission scenarios, while another XR client or the XR server 41 operates as the receiving device receiving the XR traffic flow transmitted from the transmitting device. Alternatively, the transmitting device can include an intermediate device between the UE 10 and the XR server 41. The UE 10 can include an embodiment of the UE 10a or 10b. The gNB 20 can include an embodiment of the base station 20a. It is noted that although described herein with the gNB 20 and UPF / 5GC 30b as examples, the wireless communication methods can be performed by a base station, such as another gNB, an eNB, an integrated eNB and gNB base station, or a base station for 5G and beyond technology.The UPF / 5GC 30b can include another network entity of the 5GC.

[0059] A service traffic flow 5, e.g., 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.

[0060] In the description herein, one layer, e.g., an application layer, a PDCP layer, an RLC layer, a MAC layer, or a physical layer (PHY layer or L1 layer), can be a protocol layer entity in a transmitting device or a receiving device. The protocol layer entity can be implemented by a program or a software module executed by a processor or by a hardware module in an integrated circuit (IC).

[0061] Referring to Figure 3 , an example of the transmitting device is shown as the transmitting device 10c and an example of the receiving device is shown as the receiving device 10d. The transmitting 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 transmitting device 10c transmits a PDU to the application layer 19d of the receiving device 10d through lower layers (i.e., the PDCP layer 17c, the RLC layer 16c, the MAC layer 15c, and the physical layer 14c), the layers in the transmitting device 10c serve as transmitting protocol layer entities on the transmitting side and the layers in the receiving device 10d serve as receiving protocol layer entities on the receiving side. Embodiments of the present disclosure can be implemented in the PDCP layer or the RLC layer. One or more steps (or blocks) in the embodiments of the present disclosure can be implemented as a computer program, instructions, a software module stored in a memory of the transmitting device, or a circuit or a hardware module in a processor of the transmitting device, or an IC chip, a circuit, or a plug-in of the transmitting device.

[0062] The video stream of an XR service will be encoded and compressed in the form of frames with each frame period of 1 / 60, 1 / 90 or 1 / 120 second. Since the transmitting device can divide the video stream of an XR service into multiple transmission units, encapsulate and transmit each of the transmission units into transmission packets across the network, the transmission mechanism of the XR service is actually packet-based rather than frame-based. The size of each packet can be variable, the number of packets can be variable, and configurable according to one or more parameters of the QoS requirement and 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.

[0063] Referring to Figure 4 and Figure 5 , a transmitting device (e.g. the UE 10 or the gNB 20) performs one embodiment of the disclosed method and initiates an XR service. In the transmitting device, a protocol layer entity transmits PDU of a PDU set of a service from the protocol layer entity to a lower layer according to a discard timer of the PDU set and a transmission window spanning multiple PDU sets (B101). B101 further comprises the steps in Figure 5 .

[0064] Referring to Figure 5 , the protocol layer entity starts the discard timer of the PDU set upon receiving a first service data unit (SDU) associated with the PDU set from a higher layer (C101). The protocol layer entity receives the subsequent SDU from the higher layer (C102) and determines whether 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 (C103).

[0065] 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, the protocol layer entity discards the subsequent SDU associated with the PDU set (C104).

[0066] 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).

[0067] The protocol layer entity stops the discard timer upon receiving and transmitting all the PDUs of the PDU set to the lower layer (C106). The protocol layer entity discards all the PDUs of the PDU set and stops the discard timer when the discard timer of the PDU set expires (C107). In one embodiment, the PDU set is configured with one or more of the following parameters:

[0068] • the number of packets in the PDU set;

[0069] • an indicator indicating the first PDU of the PDU set;

[0070] • an indicator indicating the last PDU of the PDU set;

[0071] • one or more SNs of dependent PDU sets within one or more DRBs dependent on the PDU set;

[0072] • one or more DRB identifiers (IDs) of dependent PDU sets between one or more DRBs dependent on the PDU set.

[0073] In one embodiment, the transmission window includes parameters of a minimum PDU set SN and a maximum PDU set SN.

[0074] In embodiments with dynamic window size or 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 from the higher layer by the protocol layer entity, and starts a new discard timer for the PDU set. The protocol layer entity generates PDUs from the newly arrived SDU for transmission to the lower layer.

[0075] In one embodiment, 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 whose at least one PDU has not been transmitted to the lower layer.

[0076] In one embodiment, the transmission window includes parameters of a minimum PDU set SN and a window size.

[0077] 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 for 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.

[0078] In one embodiment, the transmission window includes parameters of a maximum PDU set SN and a window size.

[0079] 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 that the protocol layer entity receives 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 PDUs from the newly arrived SDU for transmission to the lower layer. The protocol layer entity discards all the SDUs associated with the PDU set SNs less than the minimum PDU set SN.

[0080] In some embodiments, the transmission window is configured for a first data radio bearer (DRB).

[0081] According to PDU set inter-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 of the PDU set. The protocol layer entity updates the transmission window of the first DRB.

[0082] According to DRB inter-dependency, when the discard timer of the PDU set expires, the protocol layer entity discards all the PDUs of a first dependent PDU set in the first DRB, the first dependent PDU set being dependent on the PDU set within 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.

[0083] According to 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, all PDUs of the second dependent PDU set are dependent on the PDU set in the first DRB between DRBs. 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.

[0084] 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 by the protocol layer entity to the lower layer based on a number of PDUs of the PDU set or an indicator indicating a last PDU of the PDU set.

[0085] In one embodiment, the sending device is a base station. The number of PDUs of the PDU set is provided by a 5G core (5GC) through a NG application protocol (NGAP) message or a general packet radio service tunneling protocol - user plane (GTP-U) PDU. The indicator indicating the last PDU of the PDU set is received from the 5GC through the NGAP message or the GTP-U PDU.

[0086] In one embodiment, the sending device is a user equipment (UE). The number of PDUs of the PDU set is provided by an application layer of the UE. The indicator indicating the last PDU of the PDU set is provided by the application layer of the UE.

[0087] In one embodiment, the sending device is a base station. The period of the discard timer is configured by a 5G core (5GC) through a NG application protocol (NGAP) message or a general packet radio service tunneling protocol - user plane (GTP-U) PDU.

[0088] In one embodiment, the sending device is a user equipment (UE). The period of the discard timer is configured by a base station through a radio resource control (RRC) message, or configured by an application of the UE.

[0089] 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. Alternatively, 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.

[0090] Figure 6is a general model of the second layer responsible for the data transmission. According to the latest specifications of 3GPP TS 38.321 v17.1.0 (Medium Access Control (MAC)), 3GPP TS 38.321 v17.1.0 (Radio Link Layer (RLC)) and 3GPP TS 38.321 v17.1.0 (Packet Data Convergence Protocol (PDCP)), and considering that the XR is a real-time and interactive service, the Unacknowledged Mode (UM) of RLC is more suitable for XR services, a method to detect the failed transmission at the transmitting side is disclosed in the following.

[0091] Figure 6 is a general model of the second layer responsible for the data transmission. According to the latest specifications of 3GPP TS 38.321 v17.1.0 (Medium Access Control (MAC)), 3GPP TS 38.321 v17.1.0 (Radio Link Layer (RLC)) and 3GPP TS 38.321 v17.1.0 (Packet Data Convergence Protocol (PDCP)), and considering that the XR is a real-time and interactive service, the Unacknowledged Mode (UM) of RLC is more suitable for XR services, a method to detect the failed transmission at the transmitting side is disclosed in the following.

[0092] For the Hybrid Automatic Repeat Request (HARQ) operation in MAC, one Transport Block (TB) is supported per HARQ process, each HARQ process is associated with a HARQ process identifier. According to the principle of the HARQ operation, one TB can be transmitted or retransmitted multiple times if the transmission fails. The transmission or retransmission of the TB can be terminated when the TB is successfully transmitted, the maximum number of retransmissions is reached or the timer for the TB transmission expires. The maximum number of retransmissions and the duration of the timer can be configurable or predefined.

[0093] When the transmission or retransmission is not successful and is terminated due to reaching the maximum number of retransmissions or the timer for the TB transmission expires, the transmission of the TB can be considered as a failed transmission.

[0094] As a service provided by MAC, the MAC shall report the status information of the data transmission service to higher layers (e.g. the RLC layer). As an embodiment, the status information can include an indication of successful transmission or unsuccessful transmission of a RLC PDU.

[0095] In addition, RLC can interpret the status information from MAC as status information of the data transmission service provided by RLC to the higher layers (e.g. the PDCP layer), in particular for the UM data transmission service. As an embodiment, RLC can include an indication of successful transmission or unsuccessful transmission of a PDCP PDU to PDCP.

[0096] Data packet transmission and discard:

[0097] For the data packet discard based on the PDU set dependency, the PDU set can include multiple data packets, a method of PDU transmission to lower layer is disclosed below, based on PDU set and the dependency configuration, for data radio bearer (DRB).

[0098] The transmission window or buffer queue is defined based on PDU set, sequence number (SN) of the PDU set, data packet associated with PDU set, and PDU of the protocol layer associated with the PDU set of the DRB. The window or queue can 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}.

[0099] As an embodiment, the transmission window or buffer queue is defined based on PDCP PDU, each PDCP PDU belongs to one PDU set, and each PDU set can 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 shall only include segments of SDUs belonging to the same PDU set.

[0100] As an embodiment, the transmission window or buffer queue is defined based on RLC PDU, each RLC PDU belongs to one PDU set, and each PDU set can 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 shall only include segments of SDUs belonging to the same PDU set.

[0101] The size of the window or queue is configured and fixed: the window is defined based on minimum PDU set SN and window size. The window size can be configurable and configured when the PDCP or RLC entity is established or re-established for the DRB. The window size can be configured based on one or more characteristic parameters of the PDU set of the DRB. For the gNB side, the characteristic parameters can include periodicity, data packet jitter information, delay budget, data packet size, data packet number, which can be configured by the 5GC through NG application protocol (NGAP) message. For the UE side, the window size can be configured by the gNB through radio resource control (RRC) message.

[0102] The size of the window or queue is variable. The window is defined based on the minimum PDU set SN. The size can vary with the SN of newly arrived PDU.

[0103] A discard timer is associated with each PDU set of each DRB.

[0104] As an embodiment, when a layer (e.g. MAC, RLC or PDCP) receives a new SDU from a higher layer with a new PDU set SN, a new discard timer is started and associated with the SN of the PDU set.

[0105] For the gNB side, the 5GC (e.g. 5GC 30) can configure the same value for the expiry period of the discard timer of all PDU sets of one DRB through NGAP message. For the UE side, the gNB (e.g. gNB 20) can configure the same value for the expiry period of the discard timer of all PDU sets of one DRB through RRC message.

[0106] For the gNB side, the 5GC can configure the expiry period of the discard timer of one PDU set of one DRB through a GTP-U PDU 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 can configure the expiry period of the discard timer of one PDU set of one DRB.

[0107] A discard timer is associated with a PDU set and configured with an expiry period. The discard timer of the PDU set is started when the first SDU related to the PDU set is received.

[0108] The protocol layer entity (e.g. the PDCP, RLC or MAC layer) of the transmitting device performs data packet discard of the PDU set in response to the expiry of the discard timer of the PDU set.

[0109] The protocol layer entity stops the discard timer of the PDU set when all the PDUs of the PDU set are received and transmitted to the lower layer.

[0110] The following one or more parameters are configured for the DRB to which the PDU set belongs:

[0111] Inter-DRB dependency configuration: The information (or configuration) of the inter-DRB dependency includes a DRB identifier (ID) of a DRB that one DRB depends on, and / or a handling manner of the dependency. The DRB that is depended on is referred to as a depended DRB, and the DRB that depends on the depended DRB is referred to as a dependency DRB. For example, according to the inter-DRB dependency configuration, if one PDU set is lost or discarded, the handling manner of the inter-DRB dependency indicates whether to discard unsent PDUs of one or more other PDU sets in the "inter-DRB dependent DRB" that depend on the lost or discarded PDU set in the "inter-DRB depended DRB".

[0112] Intra-DRB dependency configuration: The intra-DRB dependency configuration indicates whether a PDU set in one DRB depends on another PDU set in the same DRB, and / or a handling manner of the dependency. The information (or configuration) of the intra-DRB dependency can include a PDU set identifier (ID) of a PDU set that one PDU set depends on, and / or a handling manner of the dependency. The PDU set that is depended on is referred to as a depended PDU set, and the PDU set that depends on the depended PDU set is referred to as a dependency PDU set. The depended PDU set and the dependency PDU set are in the same DRB. For example, if one PDU set is lost or discarded, the handling manner (or configuration) of the intra-DRB dependency indicates whether to discard unsent PDUs of the dependency PDU set in the same DRB that depends on the lost or discarded PDU set in the same DRB.

[0113] Intra-PDU set dependency configuration: The intra-PDU set dependency configuration indicates whether one or more data packets (for example, PDUs) belonging to one or more PDU sets depend on one data packet in the same PDU set, and a handling manner of the dependency. The information (or configuration) of the intra-PDU set dependency can include a PDU identifier (ID) of another PDU that one PDU depends on, and / or a handling manner of the dependency. The PDU that is depended on is referred to as a depended PDU, and the PDU that depends on the depended PDU is referred to as a dependency PDU. The depended PDU and the dependency PDU are in the same PDU set. For example, the handling manner of the intra-PDU set dependency indicates whether to discard unsent dependency PDUs in the same PDU set if one depended PDU is lost or discarded.

[0114] One or more of the following parameters are configured for each PDU set:

[0115] • Number of packets in the PDU set.

[0116] • An indicator indicating the first packet or PDU of the PDU set.

[0117] • An indicator indicating the last packet or PDU of the PDU set.

[0118] • One or more SNs of one or more “in-DRB dependent PDU sets” dependent on the PDU set, wherein the parameters can include the explicit SNs of the one or more “in-DRB dependent PDU sets” or the number of consecutive PDU sets following the PDU set.

[0119] • One or more combinations of SNs and DRB IDs of one or more “inter-DRB dependent PDU sets” dependent on the PDU set.

[0120] As shown in Figure 7 and Figure 8 , three DRBs are configured for XR service, t represents the axis in the time domain, and 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 is dependent on the DRB 1 between DRBs, and the DRB 3 is dependent on the DRB 1 and the DRB 2 between DRBs. The DRB 2 is configured with in-DRB dependency. The DRB 2 and the DRB 3 are both configured with intra-PDU set dependency. The dependency processing mode can be configured as the value of “discard”.

[0121] Basically, a window or a queue is defined for each DRB, the minimum PDU set SN of the window or the queue is named Minimum_PDU_Set_SN, and should be set to 0 when the DRB is established or re-established. A discard timer is named discard_timer(n) for PDU set SN n, and should be started and configured with an expiration period for the PDU set. In the following description, the window is taken as an example.

[0122] Window operation in the case of variable window size:

[0123] As shown in Figure 8A window is defined for each DRB, the window size is variable. The Minimum_PDU_Set_SN is used as a reference, an additional parameter Maximum_PDU_Set_SN is used to record the SN which is equal to the maximum SN of newly arrived SDU plus 1. For each SDU of a DRB received from higher layer, the SN of the SDU is associated with the SN of the PDU set and denoted as PDU_Set_SN(SDU). (Note that the following SN comparison should consider the wrap around of the PDU set SN)

[0124] • If PDU_Set_SN(SDU) < Minimum_PDU_Set_SN

[0125] ■ Discard the SDU

[0126] • Else if Minimum_PDU_Set_SN <= PDU_Set_SN(SDU) <= Maximum_PDU_Set_SN

[0127] ■ Store the SDU in the transmission buffer for transmission

[0128] • Else PDU_Set_SN(SDU) > Maximum_PDU_Set_SN

[0129] ■ Set Maximum_PDU_Set_SN = PDU_Set_SN(SDU)

[0130] ■ Start discard timer for the new PDU set (SN = Maximum_PDU_Set_SN)

[0131] ■ Store the SDU in the transmission buffer for transmission

[0132] • If all the PDUs of a PDU set are transmitted or discarded

[0133] ■ Stop the discard timer of the PDU set

[0134] ■ If the SN of the PDU set = Minimum_PDU_Set_SN

[0135] ■ Set Minimum_PDU_Set_SN to the next PDU set with at least one PDU not transmitted

[0136] Window operation with configured window size in case 1:

[0137] As Figure 9As shown, a window is defined for each DRB, the window size is configured as a static value. The Minimum_PDU_Set_SN is used as a reference, the Maximum_PDU_Set_SN for the window is equal to Minimum_PDU_Set_SN plus window size. For each SDU received from the higher layer for a DRB, the SN related to the SDU (expressed in pseudo code) 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 comparison should consider the wrap around of the PDU set SN)

[0138] • If PDU_Set_SN(SDU) < Minimum_PDU_Set_SN or PDU_Set_SN(SDU) > Maximum_PDU_Set_SN

[0139] ■ Discard the SDU

[0140] • Else Minimum_PDU_Set_SN <= PDU_Set_SN(SDU) <= Maximum_PDU_Set_SN

[0141] ■ Store the SDU in the reception buffer for transmission

[0142] • If all the PDUs of a PDU set are transmitted or discarded

[0143] ■ Stop the discard timer for the PDU set

[0144] ■ If the SN of the PDU set = Minimum_PDU_Set_SN

[0145] ◆ Set Minimum_PDU_Set_SN to the next PDU set with at least one PDU not yet transmitted

[0146] ◆ Maximum_PDU_Set_SN = Minimum_PDU_Set_SN + window size

[0147] Configure the window operation in case of window size case 2:

[0148] As Figure 7Figure 1 shows that one window is defined for each DRB, 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, the Minimum_PDU_Set_SN for the window is equal to Maximum_PDU_Set_SN minus window size. For each DRB's SDU received from higher layer, the SN PDU_Set_SN(SDU) of the PDU set related to the SDU. (Note that the following SN comparison should consider the PDU set SN wrap-around)

[0149] ■ If PDU_Set_SN(SDU) > Maximum_PDU_Set_SN

[0150] ■ Set the Maximum_PDU_Set_SN to PDU_Set_SN(SDU)

[0151] ■ Set the Minimum_PDU_Set_SN = Maximum_PDU_Set_SN - window size

[0152] ■ Discard the PDU related to the PDU set (SN < Minimum_PDU_Set_SN)

[0153] ■ Else if PDU_Set_SN(SDU) < Minimum_PDU_Set_SN

[0154] ■ Discard the SDU

[0155] ■ Else Minimum_PDU_Set_SN <= PDU_Set_SN(SDU) <= Maximum_PDU_Set_SN

[0156] ■ Store the SDU in the reception buffer for transmission

[0157] ■ If all the PDUs of a PDU set are transmitted or discarded

[0158] ■ Stop the discard timer of the PDU set

[0159] PDU set discard based on the discard timer expiry:

[0160] As shown in Figure 2, where variables k, m and n are positive integers, if the discard_timer(k) of the PDU set (SN = k) expires, the following PDU set discard and the operations related to the discard timer and the window are triggered: Figure 8

[0161] ​● Discard any unsent data PDUs in the PDU set (SN=k) described in DRB 1;

[0162] ■ Stop the discard_timer(k) of the PDU set (SN=k).

[0163] ■DRB 1's Minimum_PDU_Set_SN = k+1

[0164] ● Since the PDU set (SN=m) in DRB 2 depends on the PDU set (SN=k) in DRB 1 between DRBs, discard the unsent data PDUs in the PDU set (SN=m) in DRB 2;

[0165] ■ Stop the discard_timer(m) of the PDU set (SN=m).

[0166] ■DRB 2's Minimum_PDU_Set_SN = m+1

[0167] ●Since the PDU set (SN=n+1) in DRB 3 depends on the PDU set (SN=m) in DRB 2 between DRBs, discard the unsent data PDUs in the PDU set (SN=n+1) in DRB 3;

[0168] ■ Stop the discard_timer(n+1) of the PDU set (SN=n+1).

[0169] ● Since the PDU set (SN=n) in DRB 3 depends on the PDU set (SN=k) in DRB 1 between DRBs, discard the unsent data PDUs of the PDU set (SN=n) in DRB 3;

[0170] ■ Stop the discard_timer(n) of the PDU set (SN=n).

[0171] ■DRB 3's Minimum_PDU_Set_SN = n + 2

[0172] Packet dropping based on failed PDU transmissions:

[0173] like Figure 9 As shown, if a PDU in the PDU set (SN=m) fails to transmit, the following packet dropping and operations related to the dropping timer and the window are triggered:

[0174] ●Due to the PDU set dependency configuration in DRB 2, discard any unsent data PDUs in the PDU set (SN=m) described in DRB 2;

[0175] ■ stop the discard_timer (m) for the PDU Set (SN = m)

[0176] ■ Minimum_PDU_Set_SN = m + 1 for DRB 2

[0177] • Discard unsent data PDUs of the PDU Set (SN = m + 1) in DRB 2 due to inter-DRB dependency of the PDU Set (SN = m + 1) in DRB 2 on the PDU Set (SN = m) in DRB 1 ;

[0178] ■ stop the discard_timer (m + 1) for the PDU Set (SN = m + 1)

[0179] ■ Minimum_PDU_Set_SN = m + 1 for DRB 2

[0180] • Discard unsent data PDUs of the PDU Set (SN = n + 1) in DRB 3 due to inter-DRB dependency of the PDU Set (SN = n + 1) in DRB 3 on the PDU Set (SN = m) in DRB 2;

[0181] ■ stop the discard_timer (n + 1) for the PDU Set (SN = n + 1)

[0182] • Discard unsent data PDUs of the PDU Set (SN = n + 2) in DRB 3 due to inter-DRB dependency of the PDU Set (SN = n + 2) in DRB 3 on the PDU Set (SN = m + 1) in DRB 2;

[0183] ■ stop the discard_timer (n + 2) for the PDU Set (SN = n + 2)

[0184] Normal PDU transmission for a PDU Set:

[0185] For normal PDU transmission, the following details the basic normal transmission procedure for one PDU Set of a DRB to lower layers:

[0186] When the first SDU related to the PDU Set is received, start the discard timer and configure the expiry period and associate it with the PDU Set.

[0187] Receive SDUs from higher layers and transmit PDUs (generated from the received SDUs) to lower layers, unless packet discard occurs due to discard timer expiry or PDU transmission failure.

[0188] When all the PDUs of the PDU Set are received and transmitted to lower layers:

[0189] stop the discard timer of the PDU set;

[0190] adjust the window accordingly and update the Minimum_PDU_Set_SN to the next PDU set with at least one PDU not transmitted.

[0191] To determine that all the PDUs of a PDU set have been received and transferred to lower layers, two solutions are described in detail as follows:

[0192] Solution 1: For the gNB side, the number of PDUs of a PDU set is provided by the 5GC through NGAP message or GTP-U PDU. For the UE side, the number of PDUs of a PDU set is provided by the application layer. When the number of received and transferred PDUs 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 transferred to lower layers. In this case, the PDU reception and transfer of the PDU set can be in-order or out-of-order.

[0193] Solution 2: For the gNB side, an indicator indicating the last PDU of a PDU set is received from the 5GC through NGAP message or GTP-U PDU; for the UE side, an indicator indicating the last PDU of a PDU set is provided by the application layer. In this case, the PDU reception and transfer of the PDU set can be in-order.

[0194] As an embodiment, the PDUs of different PDU sets for one DRB should be transferred to lower layers in the order of PDU sets. That is, all the PDUs of the PDU set (SN = n) should be transferred before any PDU of the PDU set (SN = n + 1). In this case, the corresponding protocol layer should support the function of buffering the arrived PDUs in advance.

[0195] As an embodiment, the PDUs of different PDU sets for one DRB can be transferred to the lower layers in the order of arrival time, regardless of the SN order of different PDU sets.

[0196] As shown in Figure 10 the variables n, k, x, y and z are positive integers.

[0197] For DRB 1, the PDU number of each PDU set is provided as PDU_number(k), thus when the received and transmitted PDU number equals the PDU_number(k), i.e. the received PDU number = PDU_number(k), 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 (SN=k) have been received and transmitted to lower layers.

[0198] For DRB 2 / 3, when the indicators indicating the last PDU of the two PDU sets are received respectively, 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 (SN=n) and the PDU set (SN=m) have been received and transmitted to lower layers.

[0199] Figure 11 FIG. 7 is a block diagram of a wireless communication example system 700 according to embodiments of the present disclosure. Embodiments described herein can be implemented into the system using any suitable configuration of hardware and / or software. Figure 11 The system 700 is shown to include radio frequency (RF) circuitry 710, baseband circuitry 720, processing elements 730, memory / storage 740, a display 750, a camera 760, a sensor 770, and an input / output (I / O) interface 780, which are configured as shown in FIG. 7.

[0200] The processing elements 730 can include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor(s) can include any combination of general-purpose processors and dedicated processors (e.g., graphics processors and application processors). The processor(s) can be coupled with the memory / storage and configured to execute instructions stored in the memory / storage to support various applications and / or an operating system running on the system.

[0201] The radio control functions can include, but are not limited to, signal modulation, encoding, decoding, radio frequency shifting, etc. In some embodiments, the baseband circuitry can support communication with one or more wireless networks. For example, in some embodiments, the baseband circuitry can support communication with a 5G New Radio (NR) network, an LTE network, an Evolved Universal Terrestrial Radio Access Network (EUTRAN), and other wireless metropolitan area networks (WMANs), wireless local area networks (WLANs), and wireless personal area networks (WPANs). Embodiments in which the baseband circuitry is configured to support wireless communication according to a plurality of wireless protocols can be referred to as multi-mode baseband circuitry. In various embodiments, the baseband circuitry 720 can include circuitry that processes signals not strictly considered a baseband frequency, but which is functionally a part of the baseband circuitry. For example, in some embodiments, the baseband circuitry can include circuitry that processes intermediate frequencies (IFs) that are not strictly at a baseband frequency, but which are processed as a function of the baseband circuitry.

[0202] In various embodiments, the system 700 can be a mobile computing device such as, but not limited to, a notebook computer, a tablet computer, a netbook, a smartphone, etc. In various embodiments, the system can have more or less components, and / or different architectures. Where appropriate, the methods described herein can be implemented as computer programs. The computer program can be stored on a storage medium, such as a non-transitory storage medium.

[0203] The embodiments of the disclosure can employ a combination of techniques / processes in 3GPP specifications to create a final product.

[0204] If the software function 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 solutions proposed by the disclosure can be essentially or partially implemented in the form of a software product. Alternatively, part of the technical solutions 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 a plurality of instructions for causing 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 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 media capable of storing program codes.

[0205] Although the disclosure has been described in conjunction with the presently preferred embodiment(s), it is to be understood that the disclosure is not limited to the presently preferred embodiment(s), but is intended to cover various arrangements falling within the scope of the appended claims interpreted in their broadest manner.

Claims

1. A wireless communication method, executed in a wireless communication device, wherein the wireless communication device operates as a transmitting device, characterized in that, The method includes: Based on the PDU set's discard timer and the transmission window spanning multiple PDU sets, the PDUs of the PDU set served are transmitted from the protocol layer entity to the lower layer, where PDU is a protocol data unit; When the protocol layer entity receives the first SDU associated with the PDU set from a higher layer, the discard timer for the PDU set is started, where SDU is a Service Data Unit; When the protocol layer entity receives a subsequent SDU from the higher layer, and the PDU set SN associated with the subsequent SDU is less than the minimum PDU set SN of the transmission window, the subsequent SDU associated with the PDU set is discarded, where SN is the sequence number; 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, a PDU is generated from the subsequent SDU for transmission to the lower layer; The discard timer is stopped when all PDUs in the PDU set are received and transmitted to the lower layer; When the discard timer for the PDU set times out, all PDUs in the PDU set are discarded and the discard timer is stopped.

2. The method as described in claim 1, characterized in that, Configure one or more of the following parameters for the PDU set: The number of data packets in the PDU set; An indicator that points to the first PDU in the PDU set; An indicator that points to the last PDU in the PDU set; One or more SNs that depend on one or more DRBs within the PDU set, where the DRB is a data radio bearer; and One or more DRB identifiers of the dependent PDU set.

3. The method as described in claim 1, characterized in that, The PDUs of the PDU set are transmitted from the protocol layer entity to the lower layer in the order of the PDU set SN.

4. The method as described in claim 1, characterized in that, The PDUs of the PDU set are transmitted from the protocol layer entity to the lower layer in the order of their arrival time.

5. The method as described in claim 1, characterized in that, The transmission window includes parameters for the minimum PDU set SN and the maximum PDU set SN.

6. The method as described in claim 5, characterized in that, 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 to transmit to the lower layer.

7. The method as described in claim 5, characterized in that, When all PDUs in 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 that at least one PDU has not yet been transmitted to the lower layer.

8. The method as described in claim 1, characterized in that, The transmission window includes parameters such as the minimum PDU set SN and the window size.

9. The method as described in claim 8, characterized in that, 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 PDUs in 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 for which at least one PDU has not yet 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 as described in claim 1, characterized in that, The transmission window includes parameters such as the maximum PDU set SN and the window size.

11. The method as described in claim 10, characterized in that, When the PDU set SN associated with a 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 drop 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 a PDU set SN smaller than the minimum PDU set SN.

12. The method as described in claim 1, characterized in that, The transmission window is configured for the first DRB.

13. The method as described in claim 12, characterized in that, Based on the dependencies within the PDU set, when the discard timer for the PDU set expires and indicates that at least one dependent PDU in the PDU set has been 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 as described in claim 12, characterized in that, According to the dependency within the DRB, when the discard timer of the PDU set expires, the protocol layer entity discards all PDUs of the first dependent PDU set in the first DRB, and the first dependent PDU set depends on the PDU set within the same DRB; The protocol layer entity stops the discard timer for the first dependent PDU set; and The protocol layer entity updates the transmission window of the first DRB.

15. The method as described in claim 12, characterized in that, Based on 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 depend on the PDU set in the first DRB between DRBs; The protocol layer entity stops the discard timer for 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 as described in claim 1, characterized in that, The protocol layer entity determines, based on the number of PDUs in the PDU set or an indicator indicating the last PDU in the PDU set, that all SDUs in the PDU set have been received by the protocol layer entity and that all PDUs in the PDU set have been transmitted by the protocol layer entity to the lower layer.

17. The method as described in claim 16, characterized in that, The transmitting device is a base station; The number of PDUs in the PDU set is provided by the 5G core via NGAP messages or GTP-U PDUs, where NGAP is the NG Application Protocol and GTP-U is the General Packet Radio Services Tunneling Protocol - User Plane; and The indicator indicating the last PDU in the PDU set is received from the 5G core via an NGAP message or a GTP-U PDU.

18. The method as described in claim 16, characterized in that, The transmitting device is a user equipment; The number of PDUs in the PDU set is provided by the application layer of the user equipment; and The indicator that indicates the last PDU in the PDU set is provided by the application layer of the user equipment.

19. The method as described in claim 1, characterized in that, The transmitting device is a base station; The period of the discard timer is configured by the 5G core via NGAP messages or GTP-U PDUs, where NGAP is the NG application protocol and GTP-U is the General Packet Radio Services Tunneling Protocol - User Plane.

20. The method as described in claim 1, characterized in that, The transmitting device is a user equipment; The period of the discard timer is configured by the base station via radio resource control messages or by the application of the user equipment.

21. A wireless communication device, characterized in that, include: A processor configured to invoke and run a computer program stored in memory to cause a device equipped with the processor to perform the method as described in any one of claims 1 to 20.

22. A chip, characterized in that, include: A processor configured to invoke and run a computer program stored in memory to cause a device on which the chip is mounted to perform the method as described in any one of claims 1 to 20.

23. A computer-readable storage medium storing a computer program, characterized in that, The computer program causes the computer to perform the method as described in any one of claims 1 to 20.

24. A computer program product, comprising a computer program, characterized in that, The computer program causes the computer to perform the method as described in any one of claims 1 to 20.

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