Method for controlling a PDCP transmitter

Abstract

Method for controlling a PDCP transmitter A method for managing the discarding of PDCP packet data units (PDUs) in a communication system including a transmitter device and a receiver device, wherein the method in the transmitter device includes determining a corresponding relevance level for one or more of a plurality of PDUs, the relevance level corresponding to each PDU being determined based on at least one characteristic of the PDU set to which the PDU belongs; determining at least one of the plurality of PDUs to be discarded based on the determined relevance level; and transmitting at least one of the plurality of PDUs to the receiver device, wherein it is determined that the at least one transmitted PDU will not be discarded.

Description

Technical Field

[0001] The present disclosure generally relates to a method for controlling a Packet Data Convergence Protocol (PDCP) transmitter. More specifically, the present disclosure relates to Extended Reality (XR) in 3GPP 5G NR.

Background Art

[0002] Wireless communication systems are mainly deployed to address a wide range of applications, from mobile broadband, massive machine type communication to ultra-reliable low-latency communication (URLLC). Such systems enable a plurality of user equipment (UE) or mobile terminals to share a wireless medium to exchange some types of data content (such as video, audio, messaging, etc.) via a radio access network (RAN) through one or more base stations.

[0003] Examples of such wireless multi-connection communication systems include systems based on 3rd Generation Partnership Project (3GPP (registered trademark)) specifications such as the 4th Generation (4G) Long Term Evolution (LTE) or the recent 5th Generation (5G) New Radio (NR) system, or systems based on IEEE 802.11 specifications such as Wi-Fi. Among the requirements of 5G NR, there are service requirements related to Extended Reality (XR).

[0004] XR (eXtended Reality) applications are defined in 3GPP document RP-2200285 as "various types of extended, virtual, and mixed environments, where human-machine and human-human communication are performed with the assistance of handheld and wearable end-user devices", and various use cases can be found in 3GPP document TR-26.928.

[0005] Many XR applications involve interaction between a wearable device (e.g., a 3D helmet or augmented reality glasses) and an application server. The wearable device and application server can be connected via a local network (such as Wi-Fi) or a cellular network (such as a 3GPP 5G cellular network, where the application server is connected to the 5G core network portion).

[0006] Some XR applications, such as cloud gaming, involve the transfer of compressed video and audio data from the server to the UE, and location information from the UE to the server. Some XR applications, such as virtual reality, involve the transfer of compressed video data, audio data, and various types of information from the server to the wearable device. Some XR applications, such as augmented reality, involve the transfer of compressed video data, audio data, and various types of information exchanged between the wearable device and the server.

[0007] In this disclosure, information exchanged between a UE or wearable device and a server is referred to as application data. For example, application data may include one or more images, video data, audio data, location information, and various other types of information.

[0008] Video and audio data are transferred between the wearable device (or user equipment) and the server using media transport protocols such as RTP (Real-Time Protocol, RFC 3550), SRTP (Secure RTP, RFC 3711), HTTP (Hypertext Transfer Protocol, RFC 26167540), or QUIC (RFC 8999, 9000, 9001, and 9002). Video encoding and decoding can be performed according to various formats, including MPEG2, H.264, H.265, HEVC, etc.

[0009] Applications generate data in the form of encoded video, audio, or location information. This data is primarily placed in data packets by the application, with application data packets, representing a single unit of information, being generated at the application level. 3GPP has named the set of PDUs (Protocol Data Units or Packet Data Units) required to forward application data packets a "PDU set." Application data consists of one or more application data packets. Downlink, 3GPP PDUs are formatted by the core network PDU layer. Similarly, uplink, 3GPP PDUs are formatted by the UE (User Equipment) PDU layer. In 3GPP, the delimiters (start, end, length) of PDU sets are not provided by the application but are generated by the core network (per UE) via Media Transport Protocol Packet Inspection. Detailed procedures can be found in 3GPP document S2-2302696.

[0010] A PDU set consists of one or more PDUs (e.g., a frame or video slice for an XRM service used in TR 26.926) carrying a payload of one unit of information generated at the application level. In some embodiments, all PDUs in a PDU set are required by the application layer to use the corresponding unit of information. In other embodiments, the application layer can still reconstruct all or part of the information unit when some PDUs are missing. For example, one PDU set may contain data for one image or frame from a video stream. The network used to transfer application data may experience perturbations and congestion. Therefore, some PDUs in a PDU set may be missing or delayed at the receiving end (UE PDU layer on the downlink, core network UPF on the uplink).

[0011] Some embodiments of video decoders require the reception of complete application data packets (a complete PDU set) in real time in order to properly decode video. Other embodiments, on the other hand, may tolerate delayed arrival or partial delivery of data packets in the PDU set. For example, these implementations rely on Forward Error Correction (FEC) or concealment techniques.

[0012] In 3GPP document S2-2302696, a PDU set QoS parameter called PSDB (PDU set delay budget) defines the time budget allocated to the transport of PDU sets across a 5G system. This QoS parameter, defined by the application, is used by the 5G system to evaluate whether PDU sets (application data packets) are delivered in time.

[0013] In the same 3GPP document S2-2302696, another QoS parameter called PSIHI (PDU Set Integrated Handling Indication) is defined to characterize the decoder's tolerance for lost or stale data. When the PSIHI parameter is set to "true", the decoder can only process complete application data packets received in time. When PSIHI is set to "false", the decoder can tolerate both incomplete and delayed application data packets.

[0014] In a 5G system, when a set of PDUs is transmitted over the air interface, several pieces of information are available regarding the reception status of the PDUs and the elapsed time of the PDU set delay budget in the radio network portion. For example, when a set of PDUs is transmitted over the air, a RAN node (Radio Access Network Node, either UE or gNB) can detect that one PDU transmission has failed despite all retransmission and error correction mechanisms. In that case, if the PSIHI QoS parameter is set to "true", it means that the entire set of PDUs is useless to the application. Therefore, if the PDUs in this "useless" set are pending transmission over the air interface, the RAN node can consider discarding the remaining transmissions of these PDUs, thus achieving a saving of radio network resources.

[0015] In aspects of this disclosure, the PSIHI QoS parameter may be set on the UE device by the network (for example, by a base station or gNB). For example, the PSIHI parameter is considered to be set to "false" unless it is set on the UE device.

[0016] In 3GPP document RP-223502, the decommissioning of PDU sets is intended to enhance the radio access network in order to increase 5G system capacity for handling XR applications.

[0017] Returning to PDCP PDU / PDU set discard, a PDCP discard timer may be considered to determine whether a PDU set, and all or some of the PDUs belonging to this PDU set, should be discarded. When such a PDCP discard timer for a given PDU set expires, the device responsible for transmitting the PDCP PDU / PDU set (i.e., either the UE device or the base station) discards the PDU set.

[0018] However, discarding a PDU set can significantly impact the decoding of associated data streams, such as video streams, by the receiver device-level decoder, depending on the PSIHI QoS parameters associated with the PDU set being considered.

[0019] Furthermore, when considering packet dropping at the PDU set level in the presence of congestion, the impact of such PDU set dropping on the associated data stream decoding to free up radio resources may also vary depending on the PDU set importance (PSI) within the data stream being considered. For example, dropping dependent frames, or P-frames, in a video stream may be less important than dropping independent frames, or I-frames, as decoding in the decoder may be conditioned by the presence of the previous frame.

[0020] Therefore, a new mechanism is needed to manage the discarding of PDU sets, or the discarding of PDCP PDUs belonging to a PDU set, while limiting the complexity of the processing in the associated transmitter device and the delays that may arise from such a mechanism. [Overview of the Initiative]

[0021] This invention relates to control techniques for a packet data convergence protocol (PDCP) in a communication network. In particular, this disclosure aims at means for selectively discarding (or not discarding) packet unit data (PDUs) among multiple PDUs for transmission. For example, PDUs may be discarded (or not discarded) based on the level of importance of the PDU.

[0022] In a first aspect, the Disclosure provides a method for managing the discarding of PDCP packet data units (PDUs) in a communication system including a transmitter device and a receiver device, the method comprising: in the transmitter device, determining a corresponding severity level for one or more of a plurality of PDUs, wherein the severity level for each PDU is determined based on at least one characteristic of the PDU set to which the PDU belongs; determining at least one PDU from the plurality of PDUs to be discarded based on the determined severity levels (for example, depending on whether the severity level of the PDU is above or below a threshold); and transmitting at least one PDU from the plurality of PDUs to the receiver device, wherein it is determined that at least one transmitted PDU will not be discarded.

[0023] A second aspect of the present disclosure provides a method for managing the discarding of PDCP packet data units (PDUs) in a communication system including a transmitter device (e.g., a transmitter) and a receiver device (e.g., a receiver), the method comprising: in the transmitter device, determining a corresponding relevance level for one or more of a plurality of PDUs, wherein the relevance level for a PDU is determined based on at least one characteristic of the PDU set to which the PDU belongs; determining at least one of the plurality of PDUs to be discarded based on the determined relevance level; and transmitting one or more of the plurality of PDUs to the receiver device, wherein it is determined that one or more of the transmitted PDUs will not be discarded.

[0024] The method in the transmitter can reduce some congestion phenomena by discarding some PDUs, while ensuring that such discarding has a limited impact on the rendering of the data flow associated with the PDUs to be discarded. In this way, the method provides a simple and efficient means to determine the PDUs that are relatively relevant to the PDU set (e.g., most relevant to the PDU set), and thus should not be discarded. As a result, the method reduces the delay caused by managing the discard of PDUs (e.g., in the transmitter), while reducing the adverse impact on the decoding of the data stream.

[0025] The method may include determining a first corresponding relevance level of a first PDU among a plurality of PDUs and a second corresponding relevance level of a plurality of PDUs among the plurality of PDUs. The method may further include determining, based on the first corresponding relevance level, that the first PDU should be discarded, and sending the second PDU to a receiver device that has determined (e.g., based on the second corresponding relevance level) that the second PDU should not be discarded.

[0026] Optionally, the method step of determining at least one PDU to be discarded based on the determined relevance level among the plurality of PDUs is performed after the transmitter device detects a trigger event related to one or more PDUs transmitted by, or to be transmitted by, the transmitter device.

[0027] Optionally, the trigger event is the expiration of a timer associated with the PDU set or the detection of the presence of a specific type of PDU.

[0028] Optionally, the duration of the timer associated with the PDU set is based on at least one of the importance level of the PDUs belonging to the PDU set, the total number of PDUs in the PDU set, and the overall PDU set delay budget (PSDB) associated with the PDU set.

[0029] Optionally, the duration of the timer associated with the PDU set is shorter than the overall PDU set delay budget (PDSB) associated with the PDU set.

[0030] Optionally, the level of relevance of each of one or more PDUs is based on at least one of the probability of successful transmission of the PDU, the level of importance of the PDU, the ratio of PDUs with a high level of importance to PDUs with a low level of importance among a plurality of PDUs, the discard tolerance associated with the PDU set to which the PDU belongs, and the target error rate and / or PDU set error rate (PSER) associated with the target PDU or the PDU set to which the target PDU belongs.

[0031] Optionally, the importance level of a PDU can be determined relative to the importance level of at least one PDU among a plurality of target PDUs.

[0032] Optionally, the probability of successful transmission of a PDU is based on at least one of the total number of PDUs in the PDU set to which the PDU belongs, the number of PDUs in the PDU set to which the PDU belongs that have not yet been transmitted, the number of PDUs in the PDU set to which the PDU belongs that have already been transmitted, the total packet delay budget associated with the PDU, the remaining time budget remaining for the transmission of PDUs in the PDU set to which the PDU belongs that have not yet been transmitted, and the target error rate and / or PDU set error rate (PSER) associated with the target PDU or the PDU set to which the target PDU belongs.

[0033] Optionally, at least one characteristic of the PDU set to which a PDU belongs includes the PDU set importance (PSI) and the PDU set integration processing notification (PSIHI).

[0034] Optionally, at least two PDUs among a plurality of PDUs belong to the same PDU set. The at least two PDUs can have two different corresponding relevance levels.

[0035] Optionally, determining at least one PDU to be discarded includes determining a group of PDUs to be discarded based on the relevance level of all or some of the PDUs.

[0036] Optionally, one or more PDUs belonging to a group of PDUs to be discarded have a low importance level. Optionally, a low importance level may be based on one or more PDUs having a given range of PSI values.

[0037] Optionally, the decision of which group of PDUs should be discarded is based on at least one of the following: the probability of successful transmission of all or some of the low-priority PDUs within a group of PDUs; the probability of successful transmission of all or some of the high-priority PDUs within a group of PDUs; the probability of successful transmission of the first PDU from a group of PDUs; the discard tolerance associated with the PDU set to which all or some of the PDUs within a group of PDUs belong; and the ratio of high-priority PDUs to low-priority PDUs within a group of PDUs.

[0038] Optionally, PDUs belonging to one or more (e.g., a group) of PDUs to be discarded belong to different PDU sets. For example, the first PDU to be discarded may belong to the first PDU set, and the second PDU to be discarded may belong to the second PDU set.

[0039] Optionally, one or more PDUs (e.g., a group) that should be discarded must include at least one PDU with a high importance level.

[0040] The number of PDUs that are optionally decided to be discarded is determined based on the target number of PDUs to be discarded. Among multiple PDUs, several of the least relevant ones may be discarded.

[0041] Optionally, any subsequent PDUs belonging to the same PDU set as the PDU to be discarded will also be discarded.

[0042] A third aspect of this disclosure provides a transmitter device configured to perform the above method.

[0043] A fourth aspect of this disclosure provides a computer program as described in claim 18 of the appended claims.

[0044] A fifth aspect of this disclosure provides a computer-readable medium as described in claim 19 of the appended claims.

[0045] Any feature in one aspect of the present disclosure may be applied to other aspects of the present disclosure in any suitable combination. In particular, aspects of a method may be applied to aspects of an apparatus / device / unit, and vice versa.

[0046] Furthermore, features implemented in hardware may also be implemented in software, and vice versa. Any references to software and hardware features in this specification should be interpreted accordingly. For example, according to other aspects of this disclosure, a computer program is provided which includes instructions causing one or more processing units to perform any of the above-described embodiments or exemplary methods when the program is executed by one or more processing units, and a computer-readable storage medium for carrying the computer program. [Brief explanation of the drawing]

[0047] Herein, different aspects of this disclosure will be described, merely as examples, with reference to the following drawings: [Figure 1] Figure 1 is a schematic diagram showing a first exemplary wireless communication system, in which the present disclosure may be carried out according to one or more embodiments thereof; [Figure 2] Figure 2 illustrates a block schematic diagram of an exemplary configuration of a UE, which may be implemented according to one or more embodiments of this disclosure; [Figure 3] Figure 3 shows a block schematic diagram of an exemplary base station configuration in which the present disclosure may be implemented according to one or more embodiments thereof; [Figure 4] Figure 4 is a block schematic diagram showing the data plane protocol stack of a 5G NR system as shown in Figure 1; [Figure 5] Figure 5 is a block schematic diagram of an exemplary embodiment of the PDCP protocol layer according to 3GPP document TS 38.323; [Figure 6] Figure 6 is a flowchart of a method performed by an element of a wireless communication system according to one or more embodiments of the present disclosure; [Figure 7] Figure 7 is a flowchart of a method performed in a transmitter device according to one or more embodiments of the present disclosure; [Figure 8] Figure 8 is a flowchart of a method performed in a transmitter device according to one or more embodiments of the present disclosure; [Figure 9] Figure 9 is a flowchart of a method performed in a transmitter device according to one or more embodiments of the present disclosure; [Figure 10] Figure 10 is a flowchart of a method performed in a transmitter device according to one or more embodiments of the present disclosure; [Figure 11] Figure 11 is a block schematic diagram illustrating an exemplary message flow for a network to request the discarding of one or more PDU sets on a UE device. [Modes for carrying out the invention]

[0048] Figure 1 shows an exemplary wireless communication system 100, in particular a mobile wireless communication system such as a fifth-generation (5G) New Radio (NR) system supporting augmented reality (XR) services. The following description, embodiments, and examples of embodiments of the disclosure will be described in relation to a 5G NR system, but it will be understood that the disclosure is not intended to be limited to a 5G NR system and may be used in any wireless communication system supporting XR or similar services.

[0049] System 100 includes a user device (UE) 101 (or 151), which may be an augmented reality wearable, such as a virtual reality helmet or glasses, provided by a base station 110 to communicate with a core network, such as a 5G core network 102. The UE may be any wireless device, such as a wireless communication device or apparatus or terminal, an IoT device, a machine-type communication (MTC) device, a device-to-device (D2D) terminal, or a user device (e.g., a smartphone, laptop, mobile phone, tablet, camera, game console, wearable device), capable of wirelessly communicating with one or more core networks via one or more radio access networks. Base station 110 is a network node that provides an access point to the core network for the UE and is part of a radio access network (RAN) consisting of base stations 110 and 111. In NR, base stations are called next-generation node B (gNB), the RAN is next-generation (NG)RAN, and the core network is called 5GC. Hereafter, the terms RAN node, base station, and gNB are used interchangeably. Base stations 110 and 111 are interconnected by an Xn interface (as defined in 3GPP document TS 38.423) implemented over a wired or wireless link 130.

[0050] Each base station is connected to the core network 102 by an NG interface (as defined in 3GPP document TS 38.413) implemented on wired or wireless links 140 and 141. Each of these base stations controls one or more cells. For example, base station 110 controls cell 120, and base station 111 controls cell 121. A cell is a geographical area of ​​a radio network defined by the frequency used in the cell to transmit data. A cell can be uniquely identified by a UE from identification information broadcast across the geographical area. Each base station 110, 111 can serve several UEs, such as UE 101 or UE 151. When a UE establishes an RRC connection with a base station, the base station to which the UE is connected is called the UE's serving base station or source base station, and the cell controlled by the serving base station where the UE camps is called the serving cell. The interface between the gNB and the UE is a Uu interface that uses the protocol sublayers SDAP (Service Data Adaptive Protocol), PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Media Access Control), and PHY (Physical) in the user plane, and the protocol sublayers RRC (Radio Resource Control), PDCP, RLC, MAC, and PHY in the control plane.

[0051] Assume that UE101 receives and / or transmits XR data for one or more multicast XR sessions generated and / or destined for XR application server 103. The XR data is provided to base station 111, which is the base station controlling cell 121 to which UE101 is connected, via the core network 102 (through data network 160 and user plane function 161) and a transport bearer (also known as a GTP-U tunnel) 106 via link 141. The XR data is then transmitted from base station 111 to UE101 via a data radio bearer (DRB) 154. Figure 1 also shows UE151 receiving data via DRB 153. A radio bearer is a set of PHY (Layer 1) and MAC (Layer 2) parameters that enable higher-layer data connectivity between the UE and gNB. 5G NR defines several types of radio bearers: SRBs (Signaling Radio Bearers) for the control plane, DRBs (Data Radio Bearers) that enable point-to-point communication (unicast) with a single UE in the user plane, and MRBs that enable point-to-point and point-to-multipoint communication (multicast / broadcast) with multiple UEs in the user plane.

[0052] Figure 2 shows a block diagram of a UE device 205, such as UE101 or UE151 in Figure 1, according to one aspect of the present disclosure. The UE includes elements for transmitting and receiving communications, including, for example, at least one of a UE communications manager 220, an I / O controller 255, a transceiver 235, a set of antennas 245, memory 225, and a processor (CPU: central processing unit) 215. All of these elements can communicate with each other.

[0053] Memory 225 includes RAM (Random Access Memory), ROM (Read-Only Memory), or a combination of both, or, in non-exclusive examples, mass storage devices such as disks or solid-state drives. Basic Input / Output System (BIOS) instructions may be stored in memory 225.

[0054] The processor 215 is configured to execute machine-readable instructions. Execution of these machine-readable instructions causes the UE to perform various functions. These functions may involve, for example, transmission to or interaction with peripheral devices such as a keyboard, screen, mouse, etc. (not shown in Figure 2). The processor may run an operating system such as iOS, Windows, or Android. The processor 215 may be a single processor or may include two or more processors that perform the processing necessary for the operation of the UE 205. The number of processors and the assignment of processing functions to the processors are design choices for those skilled in the art.

[0055] The I / O controller 255 enables these interactions with external peripherals by providing the necessary hardware and managing input and output signals. The I / O controller 255 can interact with, for example, all or some of image capture devices, image rendering devices, audio capture devices, audio rendering devices, or sensor devices that can determine their usage location.

[0056] The transceiver 235 is configured to provide bidirectional wireless communication with other wireless devices. For example, it provides the modem and frequency shifter necessary to connect to one or more wireless networks such as Wi-Fi, Bluetooth, LTE, and 5G NR. The transceiver 235 may include a PDCP transmitter and a PDCP receiver. The PDCP transmitter and PDCP receiver may be implemented by the processor 215. The PDCP transmitter and PDCP receiver may be software-only functions implemented by the processor 215.

[0057] The wireless communication uses an antenna set 245 adapted to the spectrum of the frequency-converted signal issued from the baseband modem. The antenna set 245 may be limited to one antenna, but preferably includes several antennas to provide beamforming capability.

[0058] The UE communications manager 220 handles the establishment, control, and release of the UE's communications to the radio access network. The UE periodically receives notifications from the base station of available slots for communication between the UE and the base station. The UE then knows, in terms of time and frequency, where incoming data is expected or outgoing data must be transmitted, regardless of whether they belong to the control plane or the data plane. In an exemplary embodiment, the UE communications manager 220 implements the Uu interface.

[0059] Figure 3 shows a block diagram of a base station device 305, such as the base station or gNBs 110 and 111 of Figure 1, in which the present disclosure may be implemented according to one or more embodiments of the present disclosure. The base station device 305 includes elements for transmitting and receiving communications. For example, the base station includes at least one of a base station communications manager 320, a core network communications manager 355, a transceiver 335, a set of antennas 345, memory 325, a processor (CPU) 315, and an inter-station communications manager 365. All of these elements can communicate with each other.

[0060] The base station communication manager 320 handles communication with multiple UEs. It is responsible for establishing, controlling, and releasing these communications. In an exemplary embodiment, the base station communication manager 320 implements a Uu interface. The base station communication manager 320 includes a scheduler that assigns time-frequency slots to different UE communications. Information regarding the scheduling of these slots is periodically sent to the participating UEs.

[0061] The core network communication manager 355 manages communication between base stations and the core network. It may provide standardized NG interfaces, such as those defined by 3GPP standards, to support these communications.

[0062] The transceiver 335 is configured to provide bidirectional radio communication with other wireless devices. These devices may be UEs or even other base stations. The transceiver 335 provides the modem and frequency shifter necessary to connect to multiple UEs simultaneously using different frequency carriers in time-division duplex (TDD) or frequency-division duplex (FDD). The transceiver 335 may include a PDCP transmitter and a PDCP receiver. The PDCP transmitter and PDCP receiver may be implemented by the processor 315. The PDCP transmitter and PDCP receiver may be software-only functions implemented by the processor 315. The transceiver 335 may be limited to one antenna, but is preferably connected to an antenna set 345 which includes several antennas to provide beamforming capability.

[0063] Memory 325 includes RAM, ROM, or a combination of both, or, in non-limiting examples, mass storage devices such as disks or solid-state drives. BIOS instructions may be stored within memory 325 to support the operating system.

[0064] The inter-station communication manager 365 manages communication with other base stations. To support these communications, the inter-station communication manager 365 may provide a standardized Xn interface, such as those defined by 3GPP standards.

[0065] Figure 4 is a block schematic diagram showing the data plane protocol stack of a 5G NR system as shown in Figure 1. This data plane protocol stack is described in detail in 3GPP document TS 23.501. In the downlink direction, application server 103 connects to UPF (User Plane Function) 161 via data network 160 at the PDU layer 402 level. The PDU layer corresponds to PDUs carried between UE (User Equipment) and DN (Data Network) via PDU sessions. If the PDU session type is IPv4, IPv6, or IPv4v6, it corresponds to IPv4 packets, IPv6 packets, or both; if the PDU session type is Ethernet, it corresponds to Ethernet frames, etc. During PDU session establishment time, the core network provides session QoS parameters to the UPF, gNB, and UE. PDU session QoS parameters include XR PDU Set QoS parameters (S2-2302696): 1. PDU Set Delay Budget (PSDB); 2. PDU set error rate (PSER); and 3. PDU Integration Processing Notification (PSIHI). Previously known as PDU Set Integration Notification.

[0066] In the description of Figure 4, unless otherwise specified, PDU refers to packets processed by PDU Layer 402, while all other layers process other types of PDUs, which are prefixed by their layer name (e.g., PDCP PDU). When a PDU arrives at UPF PDU Layer 402, UPF performs application packet inspection to determine the boundaries of the PDU set. Document S2-2302696 provides an example of how to identify PDU sets when inspecting RTP / SRTP headers, RTP header extensions, H.264 RTP payloads, H.265 RTP payloads, and H.266 RTP payloads.

[0067] The PDU set identification information described in S2-2303842 is determined by the UPF and sent to the NG-RAN in the GTP-U header. The PDU set identification information includes at least one of the following: - PDU set sequence number; - Notification of the end PDU in a PDU set; - PDU sequence number within the PDU set; - PDU set size in bytes; - Identify PDU set importance, the relative importance of a PDU set compared to other PDU sets within the QoS flow.

[0068] In the uplink, the application is located on the UE. As previously described, once a PDU session is established, the UE obtains PDU session QoS parameters from the core network (the PDU session establishment procedure is defined in Section 4.3.2 of TS 23.502). When the PDU generated by application 403 arrives at UE PDU layer 402, the UE performs application packet inspection to determine the boundaries of the PDU set in the same way as described above for UPF.

[0069] In both the downlink and uplink, application 103 transmits and receives data to and from NG-RAN via a GPR tunnel (GTP-U layer 404, TS 29.281).

[0070] On the downlink, the UPF detects PDU set identification information and retrieves a set of mapping rules (e.g., filtering rules) from the core network. The filtering rules define how each PDU set is mapped to a QoS flow. QoS flows are identified by identifiers, and GTP-U PDUs are marked according to the determined QoS flow identifiers. In the gNB, the transit layer 406 extracts PDU set identification information and QoS flow identifiers from the GTP-U PDUs and maps them to SDAP QoS flows. In a single XR session, multiple PDU sets may be mapped to the same QoS flow. Alternatively (or additionally), one or more PDU sets may be mapped to different QoS flows. And, according to 3GPP document TR-38.835, in one alternative, each SDAP QoS flow may be mapped to a different PDCP DRB (Data Radio Bearer). According to a second alternative, all SDAP QoS flows from the same XR session are mapped to a single PDCP DRB.

[0071] On the uplink, the UE detects PDU set identification information at PDU layer 402 and retrieves a set of mapping rules (e.g., filtering rules) from the core network. The filtering rules define how each PDU set is mapped to a QoS flow. The UE maps the XR PDUs to the relevant SDAP QoS flows according to the filtering rules. Similar to the downlink, on the uplink, multiple PDU sets may be mapped to the same QoS flow within a single XR session, and several PDU sets may be mapped to different QoS flows within a single XR session.

[0072] In the downlink, the application layer 103 generates multiple application flows (e.g., one or more video flows and one or more audio flows) destined for a single UE. Then, in the PDU layer 402, the application flows are placed into PDU sets. Each application flow is divided into multiple PDU sets of the same or different types. Then, in the GTP-U layer 404, each PDU set type is mapped onto a QoS flow, so that multiple application flows may be multiplexed into a single QoS flow, or each application flow may be mapped to a different QoS, and an application flow may be divided into multiple QoS flows. Then, the SDAP layer 407 maps the QoS flows to DRBs (Data Radio Bearers), and each DRB is handled by a dedicated PDCP entity. Similar to QoS flows, multiple application flows may be multiplexed into a single DRB, or each application flow may be mapped to a different DRB. An application flow may also be divided into multiple DRBs.

[0073] At the uplink, the application layer 403 generates multiple application flows (e.g., one or more video flows, one or more audio flows, one or more sensing flows) destined for the application server 103. Then, at the PDU layer 402, the application flows are placed into PDU sets. Each application flow is divided into multiple PDU sets of the same or different types, and each PDU set type is mapped to a QoS flow. Thus, multiple application flows may be multiplexed into a single QoS flow, or each application flow may be mapped to a different QoS. It is also possible for an application flow to be divided into multiple QoS flows. The SDAP layer 407 then maps the QoS flows to DRBs (Data Radio Bearers), and each radio bearer is handled by a dedicated PDCP entity. Similar to QoS flows, multiple application flows may be multiplexed into a single DRB, or each application flow may be mapped to a DRB, and it is also possible for an application flow to be divided into multiple DRBs.

[0074] During the downlink, PDU set identification information calculated by the core network UPF (User Plane Function) is inserted into the GTP-U (GPRS Tunneling Protocol - User Plane, TS 29.281) header. GTP-U is the protocol used by UPF to transport data from the core network to the gNB. When the GTP-U PDU arrives at the gNB SDAP (Service Data Adaptive Layer, TS 37.324), the GTP-U header is removed, and the PDU set identification information is no longer provided in bandwidth. Therefore, the UE (receiving side) during the downlink has no access to the PDU set identification information.

[0075] On the uplink, the PDU set identifier calculated by the UE PDU layer is not inserted into any header, and therefore the PDU set identifier is not provided in bandwidth. Consequently, the gNB (receiving side) on the uplink has no access to the PDU set identifier. In summary, at all protocol layers (including the PDCP layer), the receiving entity has no knowledge of the PDU set identifier, neither on the downlink nor the uplink.

[0076] On the transmitting side (both uplink and downlink), all layers below the SDAP layer (e.g., PDCP transmitting entities) do not have access to in-band PDU set identification information, but internal mechanisms such as PDU context information are used to associate out-of-band PDU set delimiter information with each PDU. For example, in a gNB, a GTP-U receiving entity may associate out-of-band PDU set delimiter information with each PDU and pass them to the PDCP transmitting entity. Another example is in a UE, where the PDU layer may associate out-of-band PDU set delimiter information with each PDU and pass them to the PDCP transmitting entity.

[0077] Figure 5 is a block schematic diagram of an exemplary embodiment of the PDCP protocol layer (e.g., PDCP layer 401 as shown in Figure 4) of a communication system 500 according to 3GPP document TS 38.323. The PDCP layer consists of a PDCP transmitting entity 502 and a PDCP receiving entity 503. In this figure, the two PDCP entities do not belong to the same NG-RAN node. The two PDCP entities are connected by radio communication 504, which represents a simplified concatenation network representation on all lower layers from RLC to PHY. For example, the PDCP transmitting entity 502 is located on UE 101 and the PDCP receiving entity 503 is located on gNB 111. However, the disclosure is not limited to this particular example, and the PDCP transmitting entity (PDCP transmitter) 502 may be located on gNB 111, and the PDCP receiving entity (PDCP receiver) 503 may be located on UE 101.

[0078] Each NG-RAN node implements both PDCP transmit and receive entities, but for simplicity, not all of these are shown in this diagram.

[0079] Each functional block of a PDCP entity is described in detail in the 3GPP document TS 38.323. Each PDCP entity carries data for one radio bearer. A PDCP entity is associated with either a control plane or a user plane, depending on the radio bearer for which it carries data. PDCP entities associated with a DRB / MRB may be configured by an RRC layer (TS 38.331, control plane not shown in Figure 4) to use header compression or uplink data compression (UDC) 505. Robust Header Compression Protocol (ROHC), Ethernet Header Compression Protocol (EHC), and UDC are supported. Each header compression protocol is configured independently for the DRB / MRB. Compression 505 is performed by the transmitting entity 502, and decompression 509 is performed by the receiving entity 503.

[0080] The integrity protection function includes both integrity protection 506 and integrity verification 512, and is performed in the PDCP when configured by the RRC. The data units whose integrity is protected are the PDCP PDU header and the data portion of the PDCP PDU before encryption. Integrity protection is always applied to the PDCP data PDU of the SRB (Signaling Radio Bearer). Integrity protection is not applied to the PDCP control PDU.

[0081] The encryption function includes both encryption 507 and decryption 508 and is performed in the PDCP when configured. The data units to be encrypted are MAC-I (1203, 1213, 1223) and, if included in a PDCP SDU (Service Data Unit), the data portion of the PDCP Data PDU excluding the SDAP header and SDAP control PDU. Encryption is not applicable to the PDCP control PDU.

[0082] If configured, the PDCP transmitting entity 502 performs buffer sequence numbering 510, while the PDCP receiving entity 503 performs reordering and duplicate discard 511.

[0083] Referring to Figure 6, a method for managing the discarding of PDCP packet data units (PDUs) will be described. This method may be performed by one or more elements of the communication system as described above. For example, the communication system 500 may include a transmitting entity 502 (e.g., a transmitter) connected to a receiving entity 503 (e.g., a receiver), as shown in Figure 5.

[0084] The method in the transmitter device begins with method step 601, which includes determining a corresponding relevance level for one or more of a set of PDUs. The relevance level corresponding to a PDU is determined based on at least one characteristic of the set of PDUs to which the PDU belongs.

[0085] The method proceeds to step 602, which involves determining from among several PDUs at least one PDU to be discarded based on the determined relevance level.

[0086] The method then proceeds to step 603, by transmitting one or more of the multiple PDUs to the receiver device. The one or more transmitted PDUs are determined not to be discarded by the system.

[0087] Figure 7 is a flowchart illustrating an exemplary method performed by a transmitter device for managing the disposal of PDUs, according to one or more embodiments of the present disclosure.

[0088] For example, with reference to the wireless communication system shown and described therein, the transmitter device performing method 700 in Figure 7 may be a base station such as base station 111, or a UE device such as UE device 101 or 102.

[0089] The method 700 shown and described in Figure 7 may be performed by software and / or hardware elements.

[0090] If the transmitter device performing method 700 is a base station, this transmitter device may be implemented in a communication device 305, such as the one shown and described with reference to Figure 3, using the method shown and described with reference to Figure 6, which is performed by one or more processing units, such as a base station communication manager unit 320.

[0091] If the transmitter device performing method 700 is a UE device, this transmitter device may be implemented in a communication device 205, such as the one shown and described with reference to Figure 2, using the method shown and described with reference to Figure 7, which is performed by one or more processing units, such as a UE communication manager unit 220.

[0092] In the first step 701, the transmitter device detects a trigger event related to the transmission of a first PDU among several PDUs to be transmitted.

[0093] In one example, multiple PDUs to be transmitted may belong to different PDU sets and may have different levels of importance or PDU set importance (PSI), as discussed in Figure 4.

[0094] According to one aspect of this disclosure, the trigger event detected by the transmitter device may be any one of the following: - Transmission Timer, Expiration (Several aspects of this disclosure relating to the use of Transmission Timer, Expiration as a trigger event are shown in Figures 8 and 9); and - The presence of a PDU with a high level of importance among multiple PDUs transmitted (several aspects of this disclosure relating to the use of the presence of a PDU with a high level of importance among multiple PDUs transmitted as a trigger event are shown in Figure 10); and - Receipt of DISCARD NOTIFICATION message 1003 from the network, as shown in Figure 11.

[0095] In one aspect of the present disclosure, the transmit timer under consideration may be associated with the transmission of a PDU associated with either a PDU set having a high level of importance (e.g., a PDU set having a high PDU set importance (PSI) value) or a PDU set having a low level of importance (e.g., a PDU set having a low PDU set importance (PSI) value).

[0096] For example, PDU set importance (PSI) is binary information, where a PSI value of "1" means the PDU set has high importance, and a PSI value of "0" means the PDU set has low importance.

[0097] In one example, the PDU set importance (PSI) is non-binary information (for instance, the PSI value can be set to three or more different values). In such cases, a higher PSI value indicates a higher importance of the associated PDU set.

[0098] In the following explanation, the importance of a PDU, or PDU importance (e.g., the PDU importance level), is equal to the importance of the PDU set to which the PDU belongs, or the PDU set importance (PSI).

[0099] In one example, the transmit timer or transmissionTimer discussed in Figure 7 and subsequent Figures 8 to 10 is the PDCP layer discardTimer as defined in 3GPP TS 38.323. In another example, the transmit timer or transmissionTimer discussed in Figure 7 and subsequent Figures 8 to 10 is a timer managed at the PDCP layer and is different from the PDCP layer discardTimer as defined in 3GPP TS 38.323.

[0100] In one aspect of this disclosure, the duration of the transmissionTimer is less than the overall PDU set delay budget (PSDB) associated with the PDU set to which the PDU belongs.

[0101] In one aspect of this disclosure, when the transmitter device is a UE device, the duration of transmissionTimer is set by the serving base station, for example, via an RRC configuration message such as an RRCReconfiguration or RRCSetup message, as defined in TS 38.331.

[0102] In the second step 702, the transmitter device may check the level of relevance of all or some of the PDUs among the multiple PDUs being transmitted, where the level of relevance of a given PDU is a function of the PDU's characteristics, including, for example, all or some of the following: - The probability of successful transmission of a given PDU; - The level of importance of a given PDU; - The ratio of high-priority PDUs to low-priority PDUs in multiple PDUs being transmitted; - The discard tolerance associated with the PDU set to which a given PDU belongs; and - The target error rate and / or the PDU set error rate (PSER) associated with the target PDU or the PDU set to which the target PDU belongs. For example, the target error rate and / or the PDU set error rate (PSER) are considered for PDU relevance estimation only when considering the above parameters does not allow for distinction between the relevance values ​​of multiple PDUs belonging to multiple PDU sets.

[0103] In Figure 7 and subsequent Figures 8 to 10, for example, the discard tolerance may be reflected by PSIHI QoS parameters.

[0104] In Figure 7 and subsequent Figures 8 through 10, the multiple PDUs being transmitted may include all or part of the following: - SDAP PDUs delivered to PDCP transmitting entities and stored in buffer 510 as PDCP SDUs; and - PDCP PDUs delivered to lower layers where successful delivery cannot be confirmed.

[0105] In one aspect of this disclosure, the probability of successful transmission of a given PDU is a function of any one or any combination thereof: - The total number of PDUs in the PDU set to which a given PDU belongs; - The number of remaining (e.g., not yet sent) PDUs in the PDU set to which a given PDU belongs; - The number of PDUs that have been sent (e.g., already sent) in the PDU set to which a given PDU belongs; - The overall packet delay budget associated with a given PDU. In one example, the overall packet delay budget for a PDU is the PDU set delay budget (PSDB) associated with the PDU set to which the PDU belongs. In another example, depending on the PSIHI (PDU Set Integration Processing Notice), the overall packet delay budget is the PDU delay budget (PDB) associated with the PDU; - The remaining time budget left for sending any PDUs that have not yet been sent in the PDU set to which a given PDU belongs; and - The target error rate and / or the PDU set error rate (PSER) associated with the target PDU, or the PDU set to which the target PDU belongs.

[0106] In Figure 7 and subsequent Figures 8 to 10, the total number of PDUs may refer to the mean, maximum, minimum, value between the minimum and maximum, or an estimate.

[0107] In Figure 7 and subsequent Figures 8 through 10, in one example, the number of PDUs being sent (e.g., already sent) may refer to all or some of the following: - PDUs sent to lower layers where delivery confirmation was received; and - PDUs sent to lower layers with an unknown or lost delivery status.

[0108] For example, the probability of a given PDU's successful transmission increases when the ratio of the PDU being transmitted to the remaining PDUs in the PDU set to which the given PDU belongs, or to the total number of PDUs in the PDU set to which the given PDU belongs, increases. For example, the aforementioned probability may increase or decrease if the remaining time budget available for the transmission of untransmitted PDUs in the PDU set to which the given PDU belongs exceeds or falls below a predetermined threshold, or if the PDU's packet delay budget exceeds or falls below a predetermined threshold.

[0109] In one example, the probability of a given PDU successfully transmitting increases when the ratio of the remaining PDUs to the PDUs to be transmitted in the PDU set to which the given PDU belongs, or to the total number of PDUs in the PDU set to which the given PDU belongs, decreases. In another example, the aforementioned probability may increase or decrease when the remaining time budget available for transmitting the untransmitted PDUs in the PDU set to which the given PDU belongs exceeds or falls below a predetermined threshold, or when the packet delay budget of the PDU exceeds or falls below a predetermined threshold.

[0110] Then, in step 703, the transmitter device determines a group of PDUs with a low relevance level that should be discarded among the multiple PDUs to be transmitted, based on the relevance level of all or some of the PDUs to be transmitted determined in step 702.

[0111] In one aspect of this disclosure, PDUs belonging to a group of low-relevance PDUs to be discarded are selected from PDUs having a low importance level (for example, PDUs with a PSI value of "0").

[0112] By doing so, the transmitter device can reduce some congestion phenomena by discarding some PDUs, while ensuring that such discards have a limited impact on the rendering of data flows associated with the PDUs to be discarded.

[0113] In one aspect of this disclosure, the size of the group of PDUs with a low relevance level that should be discarded is based on a target number of PDUs to discard (or targetPDUToDiscard information).

[0114] For example, if the transmitter device is a UE device, the targetPDUToDiscard information is set on the UE device by its serving base station via RRC configuration messages, such as RRCReconfiguration or RRCSetup messages as defined in TS 38.331, or PDCP control PDUs as defined in TS 38.323.

[0115] For example, if the transmitting device is a UE device, the UE sends a notification of PDU discarding to the gNB indicating the size of at least the group of low-relevance PDUs to be discarded (or PDUToDiscardSize) as determined by the remote UE, in response to the UE's determination of the size of the group of low-relevance PDUs to be discarded.

[0116] For example, notification of PDU decommissioning may be an RRCReconfiguration or RRCSetup message, as defined in TS 38.331, or an RRC configuration message such as a PDCP control PDU, as defined in TS 38.323.

[0117] In one example, targetPDUToDiscard and PDUToDiscardSize have the same value. In another example, targetPDUToDiscard and PDUToDiscardSize have different values.

[0118] In one aspect of this disclosure, any subsequent PDUs belonging to the same PDU set as a PDU with a low relevance level that should be discarded may also be discarded. For example, a PDU set in which all subsequent PDUs should be discarded has a PSIHI QoS parameter set to "true" (e.g., a PDU set in which the decoder cannot tolerate both incomplete or delayed application data packets, as discussed in Figure 4).

[0119] By doing so, the transmitting device can reduce some congestion by discarding some PDUs, while optimizing network bandwidth usage, by not transmitting PDUs that are no longer needed by the decoder of the receiver device, which is responsible for decoding the data flow transmitted by the transmitting device.

[0120] In one aspect of this disclosure, PDUs with a low relevance level that should be discarded belong to a set of PDUs in which the PSIHI parameter is set to "false" (for example, a set of PDUs in which the decoder can tolerate both incomplete and delayed application data packets, as discussed in Figure 4).

[0121] In one other aspect of this disclosure, a group of PDUs with a low relevance level to be discarded may include PDUs with a high importance level. For example, such selected PDUs may belong to a set of PDUs in which the PSIHI parameter is set to "false" (for example, a set of PDUs in which the decoder can tolerate both incomplete and delayed application data packets, as discussed in Figure 4).

[0122] By assigning a priority to discard certain PDUs whose PSIHI parameter is set to "false," regardless of their actual importance, the transmitter device can reduce some congestion phenomena by discarding certain PDUs, while ensuring that such discards have a limited impact on the rendering of data flows associated with the PDUs to be discarded.

[0123] Some aspects of this disclosure relating to the estimation of the relevance of PDUs and the relevant determination of groups of PDUs to be discarded among multiple PDUs to be transmitted will be discussed further in relation to Figures 8 to 10.

[0124] Figure 8 is a flowchart illustrating an exemplary method performed by a transmitting device for managing the disposal of PDUs, according to one or more embodiments of the present disclosure.

[0125] For example, with reference to the wireless communication system shown and described therein, the transmitter device performing method 800 in Figure 8 may be a base station such as base station 111, or a UE device such as UE device 101 or 102.

[0126] The method 800 shown and described in Figure 8 may be carried out by software elements and / or hardware elements.

[0127] If the transmitter device performing method 800 is a base station, this transmitter device may be implemented in a communication device 305, such as the one shown and described with reference to Figure 3, using the method shown and described with reference to Figure 8, which is performed by one or more processing units, such as a base station communication manager unit 320.

[0128] If the transmitter device performing method 800 is a UE device, this transmitter device may be implemented in a communication device 205, such as the one shown and described with reference to Figure 2, using the method shown and described with reference to Figure 8, which is performed by one or more processing units, such as a UE communication manager unit 220.

[0129] In the first step 801, the transmitting device detects the expiration of the transmit timer (or transmissionTimer) associated with the transmission of a first PDU having a high importance level among a plurality of PDUs to be transmitted, as described in relation to Figure 7.

[0130] In one aspect of this disclosure, the duration of the transmissionTimer is shorter than the overall PDU set delay budget (PSDB) associated with the PDU set to which the PDU belongs.

[0131] In one aspect of this disclosure, the duration of transmissionTimer is a function of any one or any combination thereof: - The importance level of the PDU. For example, the higher the importance level of the PDU, the longer the transmissionTimer duration; - The total number of PDUs in the PDU set to which the first PDU belongs. For example, the more PDUs in the PDU set to which the first PDU belongs, the longer the duration of the transmissionTimer will be. - - The overall PDU set delay budget (PSDB) associated with the PDU set to which the target PDU belongs.

[0132] In one aspect of this disclosure, the duration of the transmissionTimer is shorter than the overall PDU set delay budget (PSDB) associated with the PDU set to which the target PDU belongs. In one example, the duration of the transmissionTimer is set to a predetermined ratio of the overall PDU set delay budget (PSDB) associated with the PDU set to which the target PDU belongs.

[0133] In one aspect of the present disclosure, instead of detecting the expiration of the transmit timer in step 801, the transmitter device may detect the receipt of a DISCARD NOTIFICATION message 1003 from the network, as shown in Figure 11.

[0134] In another aspect of this disclosure, as shown in Figure 11, the transmitter device may perform detection of the expiration of the transmit timer only if it has previously received a DISCARD NOTIFICATION message 1003 from the network.

[0135] In the second step 802, the transmitter device determines a group of PDUs to be discarded among the multiple PDUs to be transmitted based on one or any combination thereof: - The probability of successful transmission of all or some of the lower-priority PDUs among multiple PDUs to be transmitted; - The probability that all or some of the high-priority PDUs among the multiple PDUs to be sent will be successfully transmitted; - The probability that the transmission of the first PDU will be successful; - The discard tolerance associated with the PDU set to which all or part of the PDUs to be transmitted belong; - The ratio of high-priority PDUs to low-priority PDUs among multiple PDUs to be sent; and - The target error rate, and / or the PDU set error rate (PSER) associated with the target PDU, or the PDU set to which the target PDU belongs.

[0136] In Figure 8 and subsequent Figures 9 and 10, in one aspect of the present disclosure, the size of the group of PDUs to be discarded among a plurality of PDUs to be transmitted is based on a target number of PDUs to be discarded (or targetPDUToDiscard information).

[0137] For example, if the transmitter device is a UE device, the targetPDUToDiscard information is configured on the UE device by its serving base station via RRC configuration messages, such as the RRCReconfiguration or RRCSetup messages defined in TS 38.331.

[0138] In one aspect of this disclosure, the probability of successful transmission of a given PDU is a function of any one or any combination thereof: - The number of remaining (e.g., not yet sent) PDUs in the PDU set to which a given PDU belongs; - The number of PDUs that have been sent (e.g., already sent) in the PDU set to which a given PDU belongs; - The overall packet delay budget associated with a given PDU. For example, the overall packet delay budget of a PDU is the PDU set delay budget (PSDB) associated with the PDU set to which the PDU belongs; - The remaining time budget left for sending any PDUs that have not yet been sent in the PDU set to which a given PDU belongs; and - The target error rate, and / or the PDU set error rate (PSER) associated with the target PDU, or the PDU set to which the target PDU belongs.

[0139] For example, the probability of a given PDU's successful transmission increases when the ratio of the PDU being transmitted to the remaining PDUs in the PDU set to which the given PDU belongs, or to the total number of PDUs in the PDU set to which the given PDU belongs, increases. For example, the aforementioned probability may increase or decrease if the remaining time budget available for the transmission of untransmitted PDUs in the PDU set to which the given PDU belongs exceeds or falls below a predetermined threshold, or if the PDU's packet delay budget exceeds or falls below a predetermined threshold.

[0140] In one example, the probability of a given PDU successfully transmitting increases when the ratio of the remaining PDUs to the PDUs to be transmitted in the PDU set to which the given PDU belongs, or to the total number of PDUs in the PDU set to which the given PDU belongs, decreases. In another example, the aforementioned probability may increase or decrease when the remaining time budget available for transmitting the untransmitted PDUs in the PDU set to which the given PDU belongs exceeds or falls below a predetermined threshold, or when the packet delay budget of the PDU exceeds or falls below a predetermined threshold.

[0141] In one aspect of the present disclosure, the transmitter device determines which group of PDUs to be discarded among a plurality of PDUs to be transmitted if, when the transmissionTimer expires, the probability of successful transmission of the first PDU considered in step 801 falls below a predetermined threshold.

[0142] In one aspect of the present disclosure, if the probability of successful transmission of the first PDU considered in step 801 exceeds a predetermined threshold, the transmitter device does not have to discard any PDUs. In one aspect of the present disclosure, PDUs belonging to the group of PDUs to be discarded are selected from among PDUs having a low importance level.

[0143] By doing so, the transmitter device can reduce some congestion phenomena by discarding some PDUs, while ensuring that such discards have a limited impact on the rendering of data flows associated with the PDUs to be discarded.

[0144] In one aspect of this disclosure, any subsequent PDU belonging to the same PDU set as the PDU to be discarded may also be discarded.

[0145] By doing so, the transmitting device can reduce some congestion by discarding some PDUs, while optimizing network bandwidth usage, by not transmitting PDUs that are no longer needed by the decoder of the receiver device, which is responsible for decoding the data flow transmitted by the transmitting device.

[0146] In one aspect of this disclosure, PDUs belonging to a group of PDUs to be discarded may belong to different sets of PDUs.

[0147] In one aspect of this disclosure, the PDUs to be discarded belong to a set of PDUs in which the PSIHI parameter is set to "false" (for example, a set of PDUs in which the decoder can tolerate both incomplete and delayed application data packets, as discussed in Figure 4).

[0148] In one aspect of the present disclosure, a transmitter device may discard a PDU having a PSIHI parameter set to "false" if the probability of successful transmission of the PDU falls below a predetermined threshold. In another example, a transmitter device may discard the PDU with the lowest probability of successful transmission among PDUs having a PSIHI parameter set to "false".

[0149] In one other aspect of this disclosure, a group of PDUs to be discarded may include PDUs having a high importance level.

[0150] For example, PDUs with such a high importance level may belong to a set of PDUs in which the PSIHI parameter is set to "false" (for example, a set of PDUs in which the decoder can tolerate both incomplete and delayed application data packets, as discussed in Figure 4).

[0151] For example, the discarding of a PDU with a high importance level may depend on the PSIHI parameter settings of the PDU set for other PDUs belonging to the group of PDUs being sent.

[0152] For example, if all low-priority PDUs to be transmitted belong to a set of PDUs whose PSIHI parameter is set to "true," while the first PDU belongs to a set of PDUs whose PSIHI parameter is set to "false," the transmitter device may discard the first PDU. For example, the transmitter device may discard the first PDU, which has its PSIHI parameter set to "false," if the probability of successful transmission of the first PDU falls below a predetermined threshold.

[0153] In one example, if all low-priority PDUs to be transmitted belong to a set of PDUs whose PSIHI parameter is set to "true," while a first PDU belongs to a set of PDUs whose PSIHI parameter is set to "true," the transmitter device may discard high-priority PDUs that belong to a set of PDUs whose PSIHI parameter is set to "false." In another example, the transmitter device may discard high-priority PDUs with a PSIHI parameter set to "false" if the probability of successful transmission of the high-priority PDU falls below a predetermined threshold. In yet another example, the transmitter device may discard the PDU with the lowest probability of successful transmission among high-priority PDUs whose PSIHI parameter is set to "false."

[0154] By assigning a priority to discard certain PDUs whose PSIHI parameter is set to "false," regardless of their actual importance, the transmitter device can reduce some congestion phenomena by discarding certain PDUs, while ensuring that such discards have a limited impact on the rendering of data flows associated with the PDUs to be discarded.

[0155] In one aspect of this disclosure, any subsequent PDUs belonging to the same set of PDUs as a high-severity PDU that is to be discarded may also be discarded.

[0156] In another aspect of the present disclosure, if the ratio of high-priority PDUs to low-priority PDUs in a group of PDUs to be transmitted exceeds a predetermined threshold (for example, if the number of high-priority PDUs significantly exceeds the number of low-priority PDUs), the transmitter device may preferably discard some high-priority PDUs. In such a case, for example, the transmitter device may discard high-priority PDUs belonging to a set of PDUs that have a PSIHI parameter preferably set to "false" and / or have a low probability of successful transmission.

[0157] In another aspect of the present disclosure, if the ratio of high-priority PDUs to low-priority PDUs in a group of PDUs to be transmitted falls below a predetermined threshold (for example, if the number of low-priority PDUs significantly exceeds the number of high-priority PDUs), the transmitting device may preferably discard some of the low-priority PDUs.

[0158] In such cases, for example, the transmitter device may discard low-priority PDUs belonging to a set of PDUs that have PSIHI parameters preferably set to "false" and / or have a low probability of successful transmission.

[0159] If the first PDU considered in step 801 was not discarded in step 802, the transmitter device may reset the transmit timer associated with the first PDU in step 803. For example, the value at which the transmit timer is reset corresponds to the remaining time from the overall packet delay budget associated with the PDU set to which the first PDU belongs (for example, the time remaining for the transmission of any PDUs in the PDU set to which the first PDU belongs that have not yet been transmitted before the overall packet delay budget is consumed).

[0160] Figure 9 is a flowchart illustrating an exemplary method performed by a transmitting device for managing the disposal of PDUs, according to one or more embodiments of the present disclosure.

[0161] For example, with reference to the wireless communication system shown and described therein, the transmitter device performing method 900 in Figure 9 may be a base station such as base station 111, or a UE device such as UE device 101 or 102.

[0162] The method 800 shown and described in Figure 9 may be carried out by software and / or hardware elements.

[0163] If the transmitter device performing method 900 is a base station, this transmitter device may be implemented in a communication device 305 shown and described with reference to Figure 3, using the method shown and described with reference to Figure 9, which is performed by one or more processing units, such as a base station communication manager unit 320.

[0164] If the transmitter device performing method 900 is a UE device, this transmitter device may be implemented in a communication device 205, such as the one shown and described with reference to Figure 2, using the method shown and described with reference to Figure 9, which is performed by one or more processing units, such as a UE communication manager unit 220.

[0165] In the first step 901, the transmitting device detects the expiration of a transmit timer or transmissionTimer associated with the transmission of a first PDU of a lower importance level among a plurality of PDUs to be transmitted, as described in relation to Figure 7.

[0166] In one aspect of this disclosure, the duration of transmissionTimer is shorter than the overall PDU set delay budget (PSDB) associated with the PDU set to which the PDU belongs. In one aspect of this disclosure, the duration of transmissionTimer is a function of one or any combination thereof: - The importance level of the PDU. For example, the higher the importance level of the PDU, the longer the transmissionTimer duration; - The total number of PDUs in the PDU set to which the first PDU belongs. For example, the more PDUs in the PDU set to which the first PDU belongs, the longer the duration of the transmissionTimer will be. - The overall PDU set delay budget (PSDB) associated with the PDU set to which the target PDU belongs; and - In one aspect of this disclosure, the duration of the transmissionTimer is less than the overall PDU set delay budget (PSDB) associated with the PDU set to which the target PDU belongs.

[0167] In one example, the duration of transmissionTimer is set to a predetermined ratio of the overall PDU set delay budget (PSDB) associated with the PDU set to which the target PDU belongs.

[0168] In one aspect of this disclosure, instead of detecting the expiration of the transmit timer in step 901, the transmitter device may detect the receipt of a DISCARD NOTIFICATION message 1003 from the network, as shown in Figure 11.

[0169] In another aspect of this disclosure, as shown in Figure 11, the transmitter device may perform detection of the expiration of the transmit timer only if it has previously received a DISCARD NOTIFICATION message 1003 from the network.

[0170] In the second step 802, the transmitter device determines a group of PDUs to be discarded among the multiple PDUs to be transmitted based on one or any combination thereof: - The presence of a PDU with a high level of importance among multiple PDUs to be transmitted; - The ratio of high-priority PDUs to low-priority PDUs among multiple PDUs to be transmitted; - The probability of successful transmission of all or part of the PDUs to be transmitted, including the first PDU, among multiple PDUs to be transmitted; - The discard tolerance associated with the PDU set to which all or part of the PDUs to be transmitted belong; and - The target error rate and / or the PDU set error rate (PSER) associated with the target PDU, or the PDU set to which the target PDU belongs.

[0171] In one aspect of this disclosure, the probability of successful transmission of a given PDU is a function of any one or any combination thereof: - The number of remaining (e.g., not yet sent) PDUs in the PDU set to which a given PDU belongs; - The number of PDUs that have been sent (e.g., already sent) in the PDU set to which a given PDU belongs; - The total packet delay budget associated with a given PDU. For example, the total packet delay budget of a PDU is the PDU set delay budget (PSDB) associated with the PDU set to which the PDU belongs; - The remaining time budget left for sending any PDUs that have not yet been sent in the PDU set to which a given PDU belongs; and - The target error rate and / or the PDU set error rate (PSER) associated with the target PDU, or the PDU set to which the target PDU belongs.

[0172] For example, the probability of a given PDU's successful transmission increases when the ratio of the PDU being transmitted to the remaining PDUs in the PDU set to which the given PDU belongs, or to the total number of PDUs in the PDU set to which the given PDU belongs, increases. For example, the aforementioned probability may increase or decrease if the remaining time budget available for the transmission of untransmitted PDUs in the PDU set to which the given PDU belongs exceeds or falls below a predetermined threshold, or if the PDU's packet delay budget exceeds or falls below a predetermined threshold.

[0173] In one example, the probability of a given PDU successfully transmitting increases when the ratio of the remaining PDUs to the PDUs to be transmitted in the PDU set to which the given PDU belongs, or to the total number of PDUs in the PDU set to which the given PDU belongs, decreases. In another example, the aforementioned probability may increase or decrease when the remaining time budget available for transmitting the untransmitted PDUs in the PDU set to which the given PDU belongs exceeds or falls below a predetermined threshold, or when the packet delay budget of the PDU exceeds or falls below a predetermined threshold.

[0174] In one aspect of this disclosure, the PDUs belonging to the group of PDUs to be discarded are selected from among PDUs having a low importance level.

[0175] In one example, a transmitter device may preferably discard a first PDU. In one aspect of the present disclosure, PDUs belonging to a group of PDUs to be discarded may belong to different sets of PDUs.

[0176] In one aspect of the present disclosure, the transmitter device determines which group of PDUs to be discarded among a plurality of PDUs to be transmitted if, when the transmissionTimer expires, the probability of successful transmission of the first PDU considered in step 901 falls below a predetermined threshold.

[0177] In one aspect of the present disclosure, the transmitter device does not have to discard the first PDU if the probability of successful transmission of the first PDU considered in step 901 exceeds a predetermined threshold, or if the first PDU belongs to a set of PDUs where the PSIHI parameter is set to "true" (for example, a set of PDUs where the decoder cannot tolerate either incomplete or delayed application data packets, as discussed in Figure 4). In such a case, in one example, the transmitter device may discard a PDU (if any) with a lower severity level different from the first PDU. In such a case, the transmitter device may preferably discard a PDU with a lower severity level belonging to a set of PDUs where the PSIHI parameter is set to "false" (for example, a set of PDUs where the decoder can tolerate both incomplete and delayed application data packets).

[0178] In one aspect of this disclosure, any subsequent PDU belonging to the same PDU set as the PDU to be discarded may also be discarded.

[0179] By doing so, the transmitting device can reduce some congestion by discarding some PDUs, while optimizing network bandwidth usage, by not transmitting PDUs that are no longer needed by the decoder of the receiver device, which is responsible for decoding the data flow transmitted by the transmitting device.

[0180] In one aspect of the present disclosure, a transmitter device may add one or more high-severity PDUs to a group of PDUs that should be discarded. For example, if a first PDU belongs to a set of PDUs where the PSIHI parameter is set to "true" (e.g., a set of PDUs where the decoder cannot tolerate either incomplete or delayed application data packets), the transmitter device may add several high-severity PDUs belonging to a set of PDUs where the PSIHI parameter is set to "false" (e.g., a set of PDUs where the decoder can tolerate both incomplete and delayed application data packets) to a group of PDUs that should be discarded.

[0181] In another aspect of the present disclosure, if the ratio of high-priority PDUs to low-priority PDUs in a group of PDUs to be transmitted exceeds a predetermined threshold (for example, if the number of high-priority PDUs significantly exceeds the number of low-priority PDUs), the transmitting device may discard some high-priority PDUs in addition to the low-priority PDUs. In such a case, for example, the transmitting device may discard high-priority PDUs belonging to a set of PDUs that have a PSIHI parameter preferably set to "false" and / or have a low probability of successful transmission.

[0182] In another aspect of the present disclosure, if the ratio of high-priority PDUs to low-priority PDUs in a group of PDUs to be transmitted falls below a predetermined threshold (for example, if the number of low-priority PDUs significantly exceeds the number of high-priority PDUs), the transmitter device may discard some low-priority PDUs, preferably including the first PDU. In such a case, for example, the transmitter device may discard low-priority PDUs belonging to a set of PDUs that have a PSIHI parameter preferably set to "false" and / or have a low probability of successful transmission.

[0183] If the first PDU considered in step 901 was not discarded in step 902, the transmitter device may reset the transmit timer associated with the first PDU in step 903. For example, the value at which the transmit timer is restarted corresponds to the remaining time from the overall packet delay budget associated with the PDU set to which the first PDU belongs (for example, the time remaining for the transmission of any PDUs in the PDU set to which the first PDU belongs that have not yet been transmitted before the overall packet delay budget is consumed).

[0184] Figure 10 is a flowchart illustrating an exemplary method performed by a transmitting device for managing the disposal of PDUs according to one embodiment of the present disclosure.

[0185] For example, with reference to the wireless communication system shown and described therein, the transmitter device performing method 1000 in Figure 10 may be a base station such as base station 111, or a UE device such as UE device 101 or 102.

[0186] The method 1000 shown and described in Figure 10 may be performed by software elements and / or hardware elements.

[0187] If the transmitter device performing method 1000 is a base station, this transmitter device may be implemented in a communication device 305, such as the one shown and described with reference to Figure 3, using the method shown and described with reference to Figure 10, which is performed by one or more processing units, such as a base station communication manager unit 320.

[0188] If the transmitter device performing method 1000 is a UE device, this transmitter device may be implemented in a communication device 205, as shown and described with reference to Figure 2, using the method shown and described with reference to Figure 10, which is performed by one or more processing units, such as a UE communication manager unit 220.

[0189] In the first step 1001, the transmitter device detects the presence of several PDUs that have a high importance level among the multiple PDUs to be transmitted.

[0190] In one aspect of the present disclosure, detecting the presence of several PDUs having a high importance level among a group of PDUs to be transmitted includes (for example, consisting of) detecting the presence of at least one PDU with a high importance level among a group of PDUs to be transmitted.

[0191] In one aspect of the present disclosure, detecting the presence of several PDUs having a high importance level among a group of PDUs to be transmitted involves detecting that the ratio of PDUs with a high importance level to PDUs with a low importance level among the group of PDUs to be transmitted exceeds a predetermined threshold (for example, the number of PDUs with a high importance level is greater than the number of PDUs with a low importance level that have a predetermined margin).

[0192] In one aspect of this disclosure, detecting the presence of several PDUs with a high importance level among a group of PDUs to be transmitted involves detecting that the number of PDUs with a high importance level among the group of PDUs to be transmitted exceeds a predetermined threshold.

[0193] In one aspect of the present disclosure, instead of detecting the presence of several PDUs with a high importance level among a plurality of PDUs to be transmitted in step 1001, the transmitting device may detect the receipt of a DISCARD NOTIFICATION message 1103 from the network, as shown in Figure 11.

[0194] In another aspect of the present disclosure, the transmitting device may perform detection of the presence of several PDUs having a high importance level among several PDUs to be transmitted only if it has previously received a DISCARD NOTIFICATION message 1103 from the network, as shown in Figure 11.

[0195] In step 1002, the transmitting device determines a group of PDUs to be discarded among the multiple PDUs to be transmitted based on one or any combination thereof: - The probability of successful transmission of all or part of the PDUs to be transmitted, including the first PDU, among multiple PDUs to be transmitted; - The discard tolerance associated with the PDU set to which all or part of the PDUs to be transmitted belong; and - The ratio of high-priority PDUs to low-priority PDUs among multiple PDUs to be sent.

[0196] In one aspect of this disclosure, the probability of successful transmission of a given PDU is a function of any one or any combination thereof: - The number of remaining (e.g., not yet sent) PDUs in the PDU set to which a given PDU belongs; - The number of PDUs that have been sent (e.g., already sent) in the PDU set to which a given PDU belongs; - The total packet delay budget associated with a given PDU. For example, the total packet delay budget of a PDU is the PDU set delay budget (PSDB) associated with the PDU set to which the PDU belongs; - The remaining time budget left for sending any PDUs that have not yet been sent in the PDU set to which a given PDU belongs; and - Set the target error rate and / or the PDU set error rate (PSER) associated with the target PDU or the PDU set to which the target PDU belongs.

[0197] For example, the probability of a given PDU's successful transmission increases when the ratio of the PDU being transmitted to the remaining PDUs in the PDU set to which the given PDU belongs, or to the total number of PDUs in the PDU set to which the given PDU belongs, increases. For example, the aforementioned probability may increase or decrease if the remaining time budget available for the transmission of untransmitted PDUs in the PDU set to which the given PDU belongs exceeds or falls below a predetermined threshold, or if the PDU's packet delay budget exceeds or falls below a predetermined threshold.

[0198] In one example, the probability of a given PDU successfully transmitting increases when the ratio of the remaining PDUs to the PDUs to be transmitted in the PDU set to which the given PDU belongs, or to the total number of PDUs in the PDU set to which the given PDU belongs, decreases. In another example, the aforementioned probability may increase or decrease when the remaining time budget available for transmitting the untransmitted PDUs in the PDU set to which the given PDU belongs exceeds or falls below a predetermined threshold, or when the packet delay budget of the PDU exceeds or falls below a predetermined threshold.

[0199] In one aspect of the present disclosure, the transmitter device determines which group of PDUs to be discarded among a plurality of PDUs to be transmitted if the probability of successful transmission of the first PDU considered in step 1001 is below a predetermined threshold.

[0200] In one aspect of this disclosure, if the probability of successful transmission of the first PDU considered in step 1001 exceeds a predetermined threshold, the transmitter device does not have to discard any PDUs.

[0201] In one aspect of this disclosure, PDUs belonging to a group of PDUs to be discarded are selected from among PDUs having a low importance level. By doing so, the transmitter device can reduce some congestion phenomena by discarding some PDUs, while ensuring that such discarding has a limited impact on the rendering of data flows associated with the PDUs to be discarded.

[0202] In one aspect of this disclosure, any subsequent PDUs belonging to the same PDU set as the PDU to be discarded may also be discarded. By doing so, the transmitting device can reduce some congestion by discarding some PDUs, while optimizing network bandwidth usage by not transmitting PDUs that are no longer needed by the decoder of the receiver device, which is responsible for decoding the data flow transmitted by the transmitting device.

[0203] In one aspect of this disclosure, PDUs belonging to a group of PDUs to be discarded may belong to different sets of PDUs.

[0204] In one aspect of this disclosure, the PDUs to be discarded belong to a set of PDUs in which the PSIHI parameter is set to "false" (for example, a set of PDUs in which the decoder can tolerate both incomplete and delayed application data packets, as discussed in Figure 4).

[0205] In one aspect of the present disclosure, a transmitter device may discard a PDU having a PSIHI parameter set to "false" if the probability of successful transmission of the PDU falls below a predetermined threshold. In another example, a transmitter device may discard the PDU with the lowest probability of successful transmission among PDUs having a PSIHI parameter set to "false".

[0206] In another aspect of this disclosure, the group of PDUs to be discarded may include PDUs having a high importance level.

[0207] For example, a PDU with such a high importance level may belong to a set of PDUs in which the PSIHI parameter is set to "false" (for example, a set of PDUs in which the decoder can tolerate both incomplete and delayed application data packets, as discussed in Figure 4).

[0208] In one aspect of this disclosure, the discarding of PDUs having a high importance level may depend on the PSIHI parameter setting of the PDU set for other PDUs belonging to the group of PDUs to be transmitted.

[0209] For example, if all or part of the low-priority PDUs to be transmitted belong to a set of PDUs where the PSIHI parameter is set to "true," while all or part of the high-priority PDUs detected in step 901 belong to a set of PDUs where the PSIHI parameter is set to "false," the transmitter device may add all or part of the high-priority PDUs detected in step 901 to the group of PDUs to be discarded. For example, the transmitter device may discard a high-priority PDU with its PSIHI parameter set to "false" if the probability of successful transmission of this PDU falls below a predetermined threshold.

[0210] By assigning a priority to discard certain PDUs whose PSIHI parameter is set to "false," regardless of their actual importance, the transmitter device can reduce some congestion phenomena by discarding certain PDUs, while ensuring that such discards have a limited impact on the rendering of data flows associated with the PDUs to be discarded.

[0211] In one aspect of this disclosure, any subsequent PDUs belonging to the same set of PDUs as a high-severity PDU that is to be discarded may also be discarded.

[0212] Here again, we refer to Figure 11, a block schematic diagram showing an exemplary message flow for the network to request the discarding of one or more PDU sets in a UE device.

[0213] For example, a base station (which may correspond to base station 111 in Figure 1 as described above) may request a serving transmitter device (which may correspond to UE 101 in Figure 1) to discard some PDU sets by sending a request to discard PDU sets through a DISCARD NOTIFICATION message 1103.

[0214] In one aspect of the present invention, the DISCARD NOTIFICATION message 1103 may include a target number of PDUs / PDU sets to discard (or targetPDUToDiscard information), which will also be discussed in relation to Figures 7 to 10.

[0215] In one embodiment, the value of the target number of PDUs to be discarded (or targetPDUToDiscard information) relates to a single set of PDUs to be discarded by the transmitting device, which means that the base station may issue one DISCARD NOTIFICATION message 1103 related to a single set of PDUs.

[0216] In another embodiment, the value of the target number of PDUs to discard (or targetPDUToDiscard information) relates to multiple sets of PDUs to be discarded by the UE, which means that the base station may issue a single DISCARD NOTIFICATION message 1103 relating to multiple sets of PDUs.

[0217] For example, if the DISCARD NOTIFICATION message 1103 includes the target number of PDU sets to discard, the target number of PDU sets to discard, or targetPDUToDiscard, the information is set to 1.

[0218] For example, if the DISCARD NOTIFICATION message 1103 includes a target number of PDU sets to discard, a target number of PDU sets to discard, or targetPDUToDiscard, the information will be set to an integer of PDU sets that is exactly greater than 1.

[0219] In one aspect of the present invention, upon receiving a DISCARD NOTIFICATION message 1003, the transmitter device 1101 may perform the discard of one or more requested PDU sets, or the discard of multiple requested PDUs associated with one or more PDU sets, by applying the method defined in any one of Figures 7 to 10.

[0220] For example, the DISCARD NOTIFICATION message 1103 does not need to include information about the target number of PDUs / PDU sets to discard (or targetPDUToDiscard information).

[0221] In such a case, the transmitter device 1001 may perform the discarding of a single PDU set by applying the method defined in any one of Figures 7 to 10. In another embodiment, the DISCARD NOTIFICATION message 1103 may include a "target number of PDUs to discard" set to an infinite value. Alternatively, the DISCARD NOTIFICATION message 1103 may not include any information regarding the target number of PDUs / PDU sets to discard or targetPDUToDiscard information. Further alternatively, the DISCARD NOTIFICATION message 1103 may include information requesting the transmitter device to initiate the discarding of a PDU set / PDU.

[0222] In such a case, upon receiving the DISCARD NOTIFICATION message 1103, the transmitter device 1101 may discard a PDU set or multiple PDUs corresponding to multiple PDU sets by applying one of the methods defined in any one of Figures 7 to 10. The method may proceed until it receives a notification from the base station 1102 to stop the execution of discarding the PDU set / PDUs.

[0223] In one example, a notification from base station 1002 to stop the execution of PDU set / PDU discard is performed by the base station sending a new DISCARD NOTIFICATION message 1103 indicating that the discard operation of the transmitter device should be stopped.

[0224] In one example, notification from base station 1102 to stop the execution of PDU set / PDU discard is performed by the base station sending a DISCARD INTERRUPTION message 1105, indicating that the discard operation of the transmitter device should be stopped.

[0225] For example, once the discard operation in the transmitter device 1101 is complete, the transmitter device 1101 may send a DISCARD INFORMATION message 1104 to the base station 1102 to confirm that the discard operation (for example, previously requested via a DISCARD NOTIFICATION message 1103) has been completed.

[0226] At least one or each of the DISCARD NOTIFICATION1103, DISCARD INTERRUPTION1105, and DISCARD INFORMATION1104 messages may be RRCReconfiguration messages as defined in 3GPP TS 38.331.

[0227] This disclosure may also cover the following:

[0228] 1. Trigger of the XR discard mechanism In RAN2#122, it was agreed that the network would indicate to the UE that it is applying a PSI-based XR discard mechanism via dedicated signaling. In this regard, upon receiving such notification, the UE may perform a PSI-based XR discard based on further considerations (e.g., delay budget, PSIHI). Thus, the network's notification to the UE to apply the PSI-based XR discard mechanism can be considered a request to activate / deactivate the PSI-based XR discard mechanism at the UE level. Therefore, it may be proposed that RAN2 confirm that the network allows the UE to perform a PSI-based XR discard by sending a notification to the UE. With respect to signaling, several optimizations may be considered to limit the frequency of network discard notifications to the UE. For example, a PSI-based XR discard notification issued by the network may not be limited to the discard of a single set of PDUs, but may relate to a specific amount of PDU sets that should be discarded. Some kind of ON / OFF mechanism may be considered where the reception of a PSI-based XR discard notification in the UE initiates the discard process of a set of PDUs, which is then stopped upon further receipt of subsequent notifications from the network. Therefore, it may be proposed that the network may request the UE to perform PSI-based XR discarding for a limited number of packet / PDU sets. It may also be proposed that the network may notify the UE to start or stop performing PSI-based XR discarding.

[0229] 2. Disposal policy When the network permits the discarding of PDU sets, the UE may consider several additional criteria, along with the PSI, to distinguish which PDU sets should actually be discarded. In this regard, to distinguish one or more PDU sets to be discarded among several PDU sets having the same PSI, the UE may consider the remaining time budget for each of these PDU sets and further estimate the probability of successful transmission for these PDU sets. Thus, several early timers, different from the existing PSDB discard timer, may be considered for the discarding of PDU sets, the current value of which is considered in relation to the remaining amount of data to be transmitted for the PDU set in question. Such early timers may be used in addition to the PSI of a given PDU set. The expiration time of this early timer may be a function of the PSI. Thus, when performing PSI-based XR discarding, it may be proposed that the UE rely on an early timer different from the PSDB discard timer used to identify the PDU sets to be discarded. It may also be proposed that the value of the early timer used to perform PSI-based XR discarding may be a function of the PSI.

[0230] RAN2#122 also agreed that notifications for the discarding of several PDU sets for a UL should be configured using RRC to handle the functionality of PDU set-based discarding (for example, whether the UE discards all packets in a PDU set when one PDU is discarded). This configuration is per PDCP entity. In other words, along with PSI, the UE may consider the PSIHI associated with the PDU set to determine whether or not this PDU set should be discarded. Thus, when performing PSI-based XR discarding, it may be proposed that the UE may also rely on PSIHI notifications configured for the PDU set.

[0231] While this disclosure has been described with reference to examples and embodiments, it will be understood that this disclosure is not limited to the examples and embodiments disclosed. It will be understood by those skilled in the art that various changes and modifications can be made without departing from the scope of this disclosure as defined in the appended claims. All features disclosed in the specification (including any appended claims, abstract, and drawings) and / or all steps of any method or process disclosed so as to be may be combined in any combination, except for any combination in which at least some of such features and / or steps are mutually exclusive. Each feature disclosed in the specification (including any appended claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose unless otherwise expressly stated. Thus, unless specifically stated, each feature disclosed is merely an example of a general set of equivalent or similar functions.

[0232] In the claims, the term “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude the plural. The mere fact that different features are described in different dependent claims does not imply that combinations of these features cannot be used to one's advantage.

[0233] In the embodiments described above (i.e., exemplary configurations), the functions described may be implemented in hardware, software, firmware, or any combination thereof. When implemented in software, the functions may be stored or transmitted as one or more instructions or codes on a computer-readable medium and executed by a hardware-based processing unit.

[0234] Computer-readable media may include computer-readable storage media corresponding to tangible media such as data storage media, or communication media including any media that facilitates the transfer of computer programs from one location to another in accordance with a communication protocol, for example. Thus, computer-readable media may generally correspond to (1) non-transient tangible computer-readable storage media, or (2) communication media such as signals or carrier waves. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, code, and / or data structures for performing the techniques described herein. Computer program products may include computer-readable media.

[0235] As an example, and not an limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, flash memory, or any other media accessible by a computer that can be used to store desired program code in the form of instructions or data structures. Any connection is also appropriately called computer-readable media. For example, if instructions are transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave may be included in the definition of media. However, it should be understood that computer-readable storage media and data storage media do not include connections, carriers, signals, or other temporary media, but instead refer to non-temporary tangible storage media. As used herein, the terms "disk" and "disc" include compact discs (CDs), laser discs, optical discs, digital multipurpose discs (DVDs), floppy disks, and Blu-ray discs, where a "disk" typically reproduces data magnetically, and a "disc" reproduces data optically using a laser. Any combination of the above should also be included within the scope of computer-readable media.

Claims

1. A method for managing the discarding of PDCP packet data units (PDUs) in a communication system including a transmitter device and a receiver device, wherein in the transmitter device, Determining a corresponding relevance level for one or more of a group of PDUs, wherein the relevance level corresponding to each PDU is determined based on at least one characteristic of the PDU set to which the PDU belongs. Among the aforementioned multiple PDUs, at least one PDU to be discarded is determined based on the determined relevance level. A method comprising transmitting at least one PDU from the plurality of PDUs to the receiver device, wherein it is determined that the at least one transmitted PDU is not discarded.

2. The method according to claim 1, wherein the method step of determining the at least one PDU to be discarded is performed by the transmitter device after detecting a trigger event associated with one or more PDUs among the plurality of PDUs that are transmitted or to be transmitted by the transmitter device.

3. The aforementioned trigger event is, The expiration of the timer associated with the PDU set to which the one or more PDUs belong, and The method according to claim 2, comprising at least one of detecting the presence of a particular type of PDU.

4. The duration of the timer associated with the PDU set is The level of importance of the PDUs belonging to the PDU set, The total number of PDUs in the PDU set, and The method according to claim 3, based on at least one of the overall PDU set delay budgets (PSDBs) related to the PDU set.

5. The method according to claim 4, wherein the duration of the timer associated with the PDU set is less than the overall PDU set delay budget (PDSB) associated with the PDU set.

6. The level of relevance of each of the one or more PDUs is The probability that the transmission of the PDU will be successful, The aforementioned level of importance of the PDU, The ratio of PDUs with high importance levels to PDUs with low importance levels among the aforementioned multiple PDUs, and The discard tolerance related to the PDU set to which the PDU belongs, and The method according to any one of claims 1 to 5, based on at least one of a target error rate and / or a PDU set error rate (PSER) associated with the target PDU or the PDU set to which the target PDU belongs.

7. The probability of success of the PDU transmission is, The total number of PDUs in the PDU set to which the PDU belongs, The number of PDUs in the PDU set to which the PDU belongs that have not yet been transmitted, The number of transmitted PDUs in the PDU set to which the PDU belongs, The overall packet delay budget related to the PDU, The remaining time budget left for the transmission of the PDUs that have not yet been transmitted in the PDU set to which the PDU belongs, The method according to claim 6, based on at least one of a target error rate and / or a PDU set error rate (PSER) relating to the target PDU or the PDU set to which the target PDU belongs.

8. The at least one characteristic of the PDU set to which the PDU belongs is, PDU set importance (PSI), and The method according to any one of claims 1 to 7, comprising at least one PDU Set Integration Processing Notification (PSIHI).

9. The method according to any one of the preceding claims, wherein at least two of the plurality of PDUs belong to the same PDU set and have two different levels of relevance.

10. The method according to any one of the preceding claims, wherein the step of determining the at least one PDU to be discarded comprises determining a group of PDUs to be discarded based on the relevance level of all or some of the plurality of PDUs.

11. The method according to 10, characterized in that the PDUs belonging to the group of PDUs to be discarded have a low importance based on PDUs having a predetermined PSI value range.

12. The method step of determining the group of PDUs to be discarded is, The probability of success in transmitting all or some of the lower-priority PDUs among the plurality of PDUs, The probability of success in transmitting all or some of the high-priority PDUs among the plurality of PDUs, The probability of success of the transmission of the first PDU from the plurality of PDUs, The discard tolerance related to the PDU set to which all or part of the plurality of PDUs belong, and The method according to claim 10 or 11, based on at least one of the ratios of high-priority PDUs to low-priority PDUs in the plurality of PDUs.

13. The method according to any one of claims 10 to 12, wherein the PDUs belonging to the group of PDUs to be discarded belong to different PDU sets.

14. The method according to any one of claims 10 to 13, wherein the PDUs belonging to the group of PDUs to be discarded include at least one PDU having a high importance level.

15. The method according to any one of the preceding claims, wherein the number of PDUs determined to be discarded is determined based on a target number of PDUs to be discarded, and the number of PDUs having the lowest relevance level among the plurality of PDUs are discarded.

16. The method according to any one of the preceding claims, wherein any subsequent PDUs belonging to the same PDU set as the PDU being discarded are also discarded.

17. A transmitter device configured to perform the method described in any one of claims 1 to 16.

18. A computer program that, when executed by a transmitter device, includes an instruction causing the transmitter device to perform the method according to any one of claims 1 to 16.

19. A computer-readable medium for transporting the computer program described in claim 18.

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