PDCP discard mechanism for augmented reality in wireless networks

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. Thus, embodiments herein disclose a method for discarding, by a transmitter (100), PDCP packets for XR in a wireless network (1000). The method includes detecting whether an XR drop timer of a PDU set expires. In an embodiment, the method includes discarding a subsequent SDU / PDU of the PDU set when an XR discarding timer for a first SDU / PDU of the PDU set expires, where the discarding is completed when at least one subsequent SDU / PDU of the PDU set has been received at the PDCP entity, or a subsequent SDU / PDU of the PDU set has been received at the PDCP entity. In another embodiment, the method includes mapping a subsequent SDU / PDU of the set of PDUs to an XR drop timer of each SDU / PDU when an XR drop timer for a first SDU / PDU of the set of PDUs does not expire when the subsequent SDU / PDU of the set of PDUs is received at the PDCP entity.

Description

Technical Field

[0001] This application is based upon and derived from the benefit of Indian provisional application 202241040680 filed on July 15, 2022, the contents of which are incorporated herein by reference. The present disclosure relates to wireless networks, and more particularly to a packet data convergence protocol (PDCP) discard mechanism for extended reality (XR) in wireless networks. Background Art

[0002] Extended reality (XR) is an umbrella term for different realities including virtual reality (VR), augmented reality (AR), and mixed reality (MR), and is considered an essential technology for realizing the digital twin / metaverse. XR was incorporated into the fifth generation (5G) advanced (i.e., 3rd Generation Partnership Project (3GPP) Release 18) as an agreed work item with the goal of providing a communication system framework that meets the challenging requirements of high data rate, very low latency, and power-efficient connectivity for XR applications.

[0003] The Protocol Data Convergence Protocol (PDCP) is a layer-2 sublayer and involves multiple functions for data plane processing of transmitted packets and received packets. Functions include, but are not limited to, Service Data Unit (SDU) discard, ciphering and integrity protection, header compression on the transmitting side and reordering, deciphering and integrity verification, duplicate discard, header decompression on the receiving side. Each Radio Bearer (RB) is associated with a transmitting PDCP entity and / or a receiving PDCP entity. The SDU discard procedure involves discarding a PDCP SDU when an associated timer expires or when successful delivery of the PDCP SDU is confirmed from a peer PDCP entity, for example, through a PDCP status report.

[0004] For XR applications, existing PDCP SDU discard may not be efficient and effective because XR applications are more closely coupled with frame transmission rather than with Internet Protocol (IP) packet transmission that is typically mapped one-to-one to PDCP SDU. Therefore, existing mechanisms may result in inefficient SDU discard operations, excessive processing burden and / or waste of transmission resources, etc. Therefore, it is desirable to address the above-mentioned shortcomings or other shortcomings, or at least provide a useful alternative to the PDCP discard mechanism for XR in wireless networks.

[0005] Furthermore, 5G mobile communication technology defines a wide frequency band so that high transmission rates and new services are possible, and can be realized not only in "below 6 GHz" frequency bands such as 3.5 GHz, but also in "above 6 GHz" frequency bands called mmWave including 28 GHz and 39 GHz. Furthermore, implementation of 6G mobile communication technology (referred to as a super 5G system) in a terahertz frequency band (e.g., 95 GHz to 3 THz frequency band) has been considered in order to achieve a transmission rate fifty times faster than 5G mobile communication technology and an ultra-low latency one-tenth of that of 5G mobile communication technology.

[0006] In the early stages of 5G mobile communications technology development, in order to support services and meet performance requirements associated with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC) and massive Machine-Type Communications (mMTC), standardization is already underway on the following: beamforming and massive MIMO to mitigate radio wave path loss and increase radio wave transmission distance in millimeter waves; support for basic parameter sets (e.g., operating multiple subcarrier spacings) for efficient utilization of millimeter wave resources and dynamic operation of time slot formats; initial access technology to support multi-beam transmission and broadband; definition and operation of BandWidth Part (BWP); new channel coding methods such as Low Density Parity Check (LDPC) codes for large amounts of data transmission and polar codes for highly reliable transmission of control information; L2 preprocessing; and network slicing to provide dedicated networks dedicated to specific services.

[0007] Currently, in view of the services that 5G mobile communication technology will support, discussions are underway on improvements and performance enhancements of initial 5G mobile communication technology, and there is already physical layer standardization on technologies such as: Vehicle-to-everything (V2X), for assisting driving determination of autonomous vehicles based on information about the location and status of the vehicle sent by the vehicle, and for enhancing user convenience; New Radio Unlicensed (NR-U), for system operation that complies with various regulatory requirements in unlicensed frequency bands; NR UE energy saving; Non-Terrestrial Network (NTN), which is UE-satellite direct communication for providing coverage in areas where communication with terrestrial networks is unavailable; and positioning.

[0008] In addition, standardization is already underway in the air interface architecture / protocol area on technologies such as: Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries; Integrated Access and Backhaul (IAB) for providing nodes for network service area expansion by supporting wireless backhaul links and access links in an integrated manner; Mobility Enhancement, including conditional handover and Dual Active Protocol Stack (DAPS) handover; and Two-step Random Access for simplifying the random access procedure (2-step RACH for NR). Standardization is also already underway in the system architecture / service area on the following: 5G baseline architecture (e.g., service-based architecture or service-based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies; and Mobile Edge Computing (MEC) for receiving services based on UE location.

[0009] With the commercialization of 5G mobile communication systems, the already exponentially growing number of connected devices will be connected to the communication network, and accordingly, it is expected that enhanced functionality and performance of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research related to the following items is planned: extended reality (eXtended Reality, XR) for effectively supporting augmented reality (Augmented Reality, AR), virtual reality (Virtual Reality VR), mixed reality (Mixed Reality, MR), etc.; improving 5G performance and reducing complexity by utilizing artificial intelligence (Artificial Intelligence, AI) and machine learning (Machine Learning, ML); AI service support; metaverse service support; and drone communication.

[0010] Furthermore, such developments in 5G mobile communication systems will serve not only as a basis for developing new waveforms for providing coverage of the terahertz band for 6G mobile communication technology, multi-antenna transmission technologies (such as Full Dimensional MIMO (FD-MIMO), array antennas, and massive antennas), metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional spatial multiplexing technologies using orbital angular momentum (OAM), and reconfigurable intelligent surfaces (RIS), but also as a basis for developing full-duplex technologies for improving frequency efficiency and improving system networks for 6G mobile communication technology, AI-based communication technologies for implementing system optimization by utilizing satellites and artificial intelligence (AI) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technologies for implementing services of a level of complexity that exceeds the limits of UE operating capabilities by utilizing ultra-high performance communication and computing resources. Summary of the invention

[0011] Technical issues

[0012] A main purpose of the embodiments herein is to disclose a method for dropping PDCP for extended reality (XR) in a wireless network and a wireless network.

[0013] Another object of embodiments herein is to manage PDCP reordering and delivery for XR in a wireless network.

[0014] Another object of embodiments herein is to configure PDCP for XR in a wireless network.

[0015] Another object of embodiments herein is to provide signaling frame-based packet mapping information for XR in a wireless network.

[0016] Another object of embodiments herein is to provide PDCP discard for XR considering a PDU set based discard procedure.

[0017] Another object of embodiments herein is to provide Radio Resource Control (RRC) signaling for XR discard timer configuration and timer operation.

[0018] Another object of embodiments herein is to provide PDCP header based information for a PDU set.

[0019] Another object of embodiments herein is to provide receiver operation of XR based on in-order or out-of-order processing of PDU sets.

[0020] Another object of embodiments herein is to provide differential discard operations for different PDU sets or frames for XR services.

[0021] Solution to the problem

[0022] Therefore, an embodiment of the present invention discloses a method for discarding PDCP packets for XR in a wireless network. The method includes receiving, by a transmitter, a first SDU / PDU of a PDU set from an upper layer of a device (e.g., a UE or a network device) at a PDCP entity. In addition, the method includes: when the first SDU / PDU is received at the PDCP entity, the transmitter starts an XR discard timer for the PDU set. In addition, the method includes mapping, by the transmitter, the first SDU / PDU of the PDU set to the XR discard timer. In addition, the method includes storing, by the transmitter, the first SDU / PDU of the PDU set at a PDCP buffer. In addition, the method includes receiving, by the transmitter, at the PDCP entity, subsequent SDU / PDUs belonging to the same PDU set from an upper layer of the device. In addition, the method includes detecting, by the transmitter, whether the XR discard timer for the PDU set has expired. In an embodiment, the method includes: when an XR discard timer for a first SDU / PDU of a PDU set expires, discarding subsequent SDU / PDUs of the PDU set, wherein at least one subsequent SDU / PDU of the PDU set has been received at a PDCP entity, or the discarding is completed when at least one subsequent SDU / PDU of the PDU set is received at the PDCP entity. In another embodiment, the method includes: when an XR discard timer for a first SDU / PDU of a PDU set has not expired when a subsequent SDU / PDU of the PDU set is received at a PDCP entity, mapping the subsequent SDU / PDU of the PDU set to an XR discard timer for each SDU / PDU, and storing the subsequent SDU / PDU of the PDU set at a PDCP buffer.

[0023] In an embodiment, the method includes detecting, by the transmitter, expiration of an XR discard timer for a PDU set or loss of at least one SDU / PDU constituting the PDU set or successful delivery of all SDU / PDUs constituting the PDU set. In addition, the method includes: when the XR discard timer for the PDU set expires or the loss of at least one SDU / PDU constituting the PDU set is detected or the successful delivery of all SDU / PDUs constituting the PDU set is detected, the transmitter discards the PDU set including the first SDU / PDU mapped to the XR discard timer for the PDU set and the subsequent SDU / PDUs.

[0024] In an embodiment, the method includes detecting, by the transmitter, the expiration of an XR discard timer for at least one SDU / PDU of a PDU set, the loss of at least one SDU / PDU constituting the PDU set, or the successful delivery of all SDU / PDUs constituting the PDU set. In addition, the method includes: when the XR discard timer for at least one SDU / PDU of the PDU set expires, or the loss of at least one SDU / PDU constituting the PDU set is detected, or the successful delivery of all SDU / PDUs constituting the PDU set is detected, the transmitter discards the PDU set including the first SDU / PDU of the PDU set and the subsequent SDU / PDUs.

[0025] In an embodiment, the method includes adding, by the transmitter, at least one of a frame start indication indicating a first SDU / PDU of a PDU set, a frame continuation indication indicating a subsequent SDU / PDU of the PDU set, and a frame end indication indicating a last SDU / PDU of the PDU set in a PDCP header in each SDU / PDU. In addition, the method includes sending, by the transmitter, at least one of the first SDU / PDU and the subsequent SDU / PDU belonging to the same PDU set to the receiver.

[0026] In an embodiment, when a first SDU / PDU is received at a PDCP entity, starting an XR discard timer for a PDU set by a transmitter includes: receiving an XR radio bearer configuration in a radio resource control (RRC) signaling from a network device by the transmitter, wherein the XR radio bearer configuration includes at least one of an XR discard timer configuration and a PDU set integrated processing indication (or may be referred to as a PDU set discard indication for a PDCP entity), the PDU set integrated processing indication indicating whether the PDU set is allowed to be discarded at the transmitter; and one of the following: the method includes: when a first SDU / PDU is received at a PDCP entity, starting an XR discard timer for a PDU set by the transmitter, and when a corresponding SDU / PDU of the PDU set is received at the PDCP entity, starting an XR discard timer for the SDU / PDU of the PDU set by the transmitter.

[0027] In an embodiment, discarding the first SDU / PDU and subsequent SDU / PDU of a PDU set includes: detecting, by the transmitter, whether the PDU set integration processing indication indicates that discarding of the PDU set is allowed at the transmitter; and one of the following: discarding the first SDU / PDU and subsequent SDU / PDU of the PDU set when the PDU set integration processing indication indicates that discarding of the PDU set is allowed at the transmitter, and discarding the corresponding SDU / PDU when the PDU set integration processing indication indicates that discarding of the PDU set is not allowed at the transmitter.

[0028] In an embodiment, the transmitter is configured with at least one discard timer value for different frame types, wherein the transmitter starts the XR discard timer with an appropriate discard timer value based on the type of frame associated with the SDU.

[0029] Therefore, an embodiment of the present invention discloses a method for discarding PDCP packets of XR in a wireless network. The method includes receiving, by a receiver, an XR radio bearer configuration in a radio resource control (RRC) signaling from a network device. The XR radio bearer configuration includes a frame delivery permission indication being configured, the frame delivery permission indication indicating whether a complete set of received PDUs is allowed to be delivered from the receiver. In addition, the method includes receiving, by a receiver, a plurality of SDUs / PDUs belonging to a PDU set, wherein a PDCP header in each of the SDUs / PDUs includes a frame start indication indicating the first SDU / PDU of the PDU set, a frame continuation indication indicating the subsequent SDU / PDU of the PDU set, and at least one of a frame end indication indicating the last SDU / PDU of the PDU set. In addition, the method includes detecting, by a receiver, whether a frame delivery permission indication indicating that the PDU / SDU is allowed to be delivered from the receiver is configured. In an embodiment, the method includes: when a frame delivery permission indication indicating that a complete set of received PDUs is allowed to be delivered from the receiver is configured, after receiving the complete set of PDUs, a plurality of SDUs / PDUs belonging to the PDU set are delivered to an upper layer entity. In another embodiment, the method includes reordering a plurality of SDUs / PDUs belonging to the PDU set based on a PDCP header of the SDU / PDU when a frame delivery allow indication indicating that a completely received PDU set is allowed to be delivered from a receiver is not configured, and delivering each of the plurality of SDUs / PDUs belonging to the PDU set to an upper layer entity based on the reordering.

[0030] In an embodiment, delivering each of the plurality of SDUs / PDUs belonging to the PDU set to an upper layer entity based on expiration of a reordering timer comprises: decompressing, by the receiver, the PDCP header based on at least one of: all stored SDUs / PDUs with associated COUNT values ​​less than RX_REORD related to the complete received PDU set, and all stored SDUs / PDUs with associated COUNT values ​​starting from RX_REORD related to the complete received PDU set, wherein RX_REORD indicates a PDCP data PDU associated with the triggering reordering timer. the COUNT value after the COUNT value of RX_REORD, discard by the receiver all stored SDUs / PDUs having associated (multiple) COUNT values ​​less than RX_REORD related to the incompletely received PDU, each of the multiple SDUs / PDUs belonging to the set of completely received PDUs is delivered to the upper layer entity in ascending order of the associated COUNT values, update RX_DELIV to the COUNT value of the first SDU / PDU that has not been delivered to the upper layer, wherein the COUNT value is greater than or equal to RX_REORD, wherein RX_DELIV indicates the COUNT value of the first PDCP SDU that has not been delivered to the upper layer, and update RX_REORD to RX_NEXT by the receiver, and if RX_DELIV is less than RX_NEXT, start a reordering timer, wherein RX_NEXT indicates the COUNT value of the next PDCP SDU expected to be received.

[0031] Therefore, an embodiment of the present invention discloses a transmitter for discarding a PDCP for XR in a wireless network. The transmitter includes a PDCP discard controller, which is communicatively coupled to a memory and a processor. The PDCP discard controller is configured to receive a first SDU / PDU of a PDU set from an upper layer of a device at a PDCP entity. In addition, the PDCP discard controller is configured to start an XR discard timer for the PDU set when the first SDU / PDU is received at the PDCP entity. Further, the PDCP discard controller is configured to map the first SDU / PDU of the PDU set to the XR discard timer. In addition, the PDCP discard controller is configured to store the first SDU / PDU of the PDU set at a PDCP buffer. In addition, the PDCP discard controller is configured to receive subsequent SDU / PDUs belonging to the same PDU set from an upper layer entity of the device at the PDCP entity. Further, the PDCP discard controller is configured to detect whether the XR discard timer for the PDU set has expired. In an embodiment, the PDCP discard controller is configured to discard subsequent SDUs / PDUs of the PDU set when an XR discard timer for a first SDU / PDU of the PDU set expires, wherein the discarding is completed when at least one subsequent SDU / PDU of the PDU set has been received at the PDCP entity, or when at least one subsequent SDU / PDU of the PDU set is received at the PDCP entity. In another embodiment, the PDCP discard controller is configured to: when the XR discard timer for the first SDU / PDU of the PDU set has not expired when the subsequent SDU / PDU of the PDU set is received at the PDCP entity, map the subsequent SDUs / PDUs of the PDU set to the XR discard timer of each SDU / PDU, and store the subsequent SDUs / PDUs of the PDU set at the PDCP buffer.

[0032] Therefore, an embodiment of the present invention discloses a receiver for discarding a PDCP of an XR in a wireless network. The receiver includes a PDCP discard controller, which is communicatively coupled to a memory and a processor. The PDCP discard controller is configured to receive an XR radio bearer configuration in a radio resource control (RRC) signaling from a network device. The XR radio bearer configuration includes a frame delivery permission indication configured, which indicates whether a completely received PDU set is allowed to be delivered from the receiver. In addition, the PDCP discard controller is configured to receive multiple SDUs / PDUs belonging to the PDU set. The PDCP header in each of the SDUs / PDUs includes a frame start indication representing the first SDU / PDU of the PDU set, a frame continuation indication representing the subsequent SDU / PDU of the PDU set, and at least one of a frame end indication representing the last SDU / PDU of the PDU set. In addition, the PDCP discard controller is configured to detect whether the frame delivery permission indication indicates that the PDU / SDU is allowed to be delivered from the receiver. In an embodiment, the PDCP discard controller is configured to: when a frame delivery allow indication indicating that a complete received PDU set is allowed to be delivered from a receiver is configured, after receiving the complete PDU set, transmit a plurality of SDUs / PDUs belonging to the PDU set to an upper layer entity. In another embodiment, the PDCP discard controller is configured to, when a frame delivery allow indication indicating that a complete received PDU set is allowed to be delivered from a receiver is not configured, reorder the plurality of SDUs / PDUs belonging to the PDU set based on a PDCP header of the SDUs / PDUs, and deliver each of the plurality of SDUs / PDUs belonging to the PDU set to an upper layer entity based on the reordering.

[0033] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and accompanying drawings. However, it should be understood that the following description, although indicating preferred embodiments and many of their specific details, is given by way of illustration and not limitation. Many changes and modifications may be made within the scope of the embodiments herein, and the embodiments herein include all such modifications.

[0034] Advantageous Effects of the Invention

[0035] According to an embodiment of the present disclosure, a wireless network for dropping a PDCP for extended reality (XR) may be effectively performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The method and wireless network are shown in the accompanying drawings, and the same reference numerals indicate corresponding parts in the various drawings throughout the drawings. The embodiments of the present invention will be better understood from the following description with reference to the accompanying drawings, in which:

[0037] Figure 1A wireless network for discarding PDCP packets for XR according to embodiments disclosed herein is shown;

[0038] Figure 2 shows various hardware components of a transmitter according to embodiments disclosed herein;

[0039] Figure 3 shows various hardware components of a receiver according to embodiments disclosed herein;

[0040] Figure 4 is a flow chart illustrating a method implemented by a transmitter for discarding PDCP packets for XR in a wireless network according to an embodiment disclosed herein;

[0041] Figure 5 is a flow chart illustrating a method implemented by a receiver for discarding PDCP packets for XR in a wireless network according to an embodiment disclosed herein;

[0042] Figure 6 is a flow chart illustrating a PDCP discard mechanism at a transmitting PDCP entity (ie, a transmitter) for XR in a wireless network according to embodiments disclosed herein;

[0043] Figure 7 is a flow chart illustrating a PDCP discard mechanism at a transmitting PDCP entity for XR based on configuration parameters in a wireless network according to embodiments disclosed herein;

[0044] Figure 8 is a flow chart illustrating a PDCP reordering and delivery mechanism at a receiving PDCP entity (ie, a receiver) for XR in a wireless network according to embodiments disclosed herein;

[0045] Fig. 9 is a flow chart illustrating a method for transmitting frame-PDCP SDU mapping information for XR in a wireless network according to an embodiment disclosed herein;

[0046] Fig.10 is a flow chart illustrating a PDCP delivery mechanism when a reordering timer expires at a transmitting PDCP entity for XR in a wireless network according to embodiments disclosed herein; and

[0047] Fig.11 Various sample XR bearer data PDU formats with one or more sequence number and frame indicator field sub-sequence number fields according to embodiments disclosed herein are shown.

[0048] Fig.12 Various sample XR bearer data PDU formats with one or more sequence number and frame indicator field sub-sequence number fields according to embodiments disclosed herein are shown.

[0049] Fig.13 Various sample XR bearer data PDU formats with one or more sequence number and frame indicator field sub-sequence number fields according to embodiments disclosed herein are shown.

[0050] Fig.14 Various sample XR bearer data PDU formats with one or more sequence number and frame indicator field sub-sequence number fields according to embodiments disclosed herein are shown.

[0051] It may be noted that, to the extent possible, the same reference numerals have been used to represent the same elements in the drawings. Furthermore, it will be appreciated by those of ordinary skill in the art that the elements in the drawings are illustrated for simplicity and may not necessarily be drawn to scale. For example, the dimensions of some elements in the drawings may be exaggerated relative to other elements to help improve understanding of various aspects of the present invention. Furthermore, one or more elements may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details relevant to understanding embodiments of the present invention so as not to obscure the drawings with details that would be readily apparent to those of ordinary skill in the art having the benefit of the description herein. DETAILED DESCRIPTION

[0052] The embodiments of this article and its various features and advantageous details are explained more fully with reference to the non-limiting embodiments shown in the drawings and described in detail in the following description. The description of known components and processing techniques is omitted so as not to unnecessarily obscure the embodiments of this article. In addition, the various embodiments described herein are not necessarily mutually exclusive, because some embodiments can be combined with one or more other embodiments to form new embodiments. Unless otherwise stated, the term "or" as used herein refers to a non-exclusive or. The examples used herein are intended only to facilitate understanding of the manner in which the embodiments of this article can be practiced, and further enable those skilled in the art to practice the embodiments of this article. Therefore, the examples should not be interpreted as limiting the scope of the embodiments of this article.

[0053] As is conventional in the art, embodiments may be described and illustrated according to blocks that perform one or more functions described. These blocks, which may be referred to herein as units or modules, are physically implemented by analog or digital circuits (such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hard-wired circuits, etc.), and may optionally be driven by firmware. The circuit may be, for example, embodied in one or more semiconductor chips, or embodied on substrate supports such as printed circuit boards. The circuits constituting the blocks may be implemented by dedicated hardware, or by a processor (e.g., one or more programmed microprocessors and associated circuits), or by a combination of dedicated hardware that performs some functions of the blocks and processors that perform other functions of the blocks. Without departing from the scope of the present invention, each block of the embodiment may be physically divided into two or more interacting and discrete blocks. Similarly, without departing from the scope of the present invention, the blocks of the embodiment may be physically combined into more complex blocks.

[0054] The accompanying drawings are used to help easily understand various technical features, and it should be understood that the embodiments presented herein are not limited by the accompanying drawings. Therefore, the present disclosure should be interpreted as extending to any changes, equivalents and substitutes other than those specifically set forth in the accompanying drawings. Although the terms first, second, etc. can be used to describe various elements in this article, these elements should not be limited by these terms. These terms are usually only used to distinguish one element from another element.

[0055] In embodiments of the present invention, terms and classifications such as frame, XR frame, SDU set, PDU set, packet group, and slice may be used interchangeably. Furthermore, in embodiments of the present invention, terms such as priority and importance may be used interchangeably. Furthermore, in embodiments of the present invention, terms such as XR radio bearer, radio bearer, and data radio bearer may be used interchangeably. Therefore, these terms need to be considered without loss of generality or specificity.

[0056] Therefore, an embodiment of the present invention discloses a method for discarding PDCP packets of XR in a wireless network. The method includes receiving, by a transmitter, a first SDU / PDU of a PDU set from an upper layer of a device at a PDCP entity. In addition, the method includes: when the first SDU / PDU is received at the PDCP entity, the transmitter starts an XR discard timer for the PDU set. In addition, the method includes mapping, by the transmitter, the first SDU / PDU of the PDU set to the XR discard timer. In addition, the method includes storing, by the transmitter, the first SDU / PDU of the PDU set at a PDCP buffer. In addition, the method includes receiving, by the transmitter, at the PDCP entity, subsequent SDU / PDUs belonging to the same PDU set from an upper layer entity of the device. In addition, the method includes detecting, by the transmitter, whether the XR discard timer for the PDU set has expired. In an embodiment, the method includes: when an XR discard timer for a first SDU / PDU of a PDU set expires, discarding subsequent SDU / PDUs of the PDU set, wherein at least one subsequent SDU / PDU of the PDU set has been received at a PDCP entity, or the discarding is completed when at least one subsequent SDU / PDU of the PDU set is received at the PDCP entity. In another embodiment, the method includes: when an XR discard timer for a first SDU / PDU of a PDU set has not expired when a subsequent SDU / PDU of the PDU set is received at a PDCP entity, mapping the subsequent SDU / PDU of the PDU set to an XR discard timer for each SDU / PDU, and storing the subsequent SDU / PDU of the PDU set at a PDCP buffer.

[0057] The proposed method can be used to manage PDCP reordering and delivery for extended reality in a wireless network. The proposed method can be used to configure PDCP for extended reality in a wireless network. The proposed method can be used to provide signaling frame-based packet mapping information for extended reality in a wireless network.

[0058] In conventional methods, the SDU discard process involves discarding the PDCP SDU when an associated timer expires or when successful delivery of the PDCP SDU is confirmed from a peer PDCP entity, for example, via a PDCP status report. For XR applications, existing PDCP SDU discard may not be efficient and effective because XR applications are more closely coupled with frame transmission rather than with IP packet transmission that is typically mapped one-to-one to PDCP SDUs. Therefore, existing mechanisms may result in inefficient SDU discard operations, excessive processing burden, and / or waste of transmission resources, etc. The proposed method provides an enhanced PDCP SDU discard mechanism for XR. The proposed method provides efficient and effective PDCP discard operations, thereby ensuring timely delivery of packets and saving of transmission resources for XR applications. Therefore, UE and network XR service performance is significantly improved with efficient transmission resource usage and lower latency.

[0059] Referring now to the drawings, and more particularly to Figures 1 to 14 , showing a preferred embodiment.

[0060] Figure 1 A wireless network (1000) for discarding PDCP packets for XR according to an embodiment disclosed herein is shown. The wireless network (1000) includes a UE (300) (e.g., a smart phone, an immersive device, a laptop, an IoT device, a TV, etc.) and a network device (400), each of which may include a transmitter (100a and 100b) (i.e., a transmitting PDCP entity) and a receiver (200a and 200b) (i.e., a receiving PDCP entity). The PDCP entity is in both the UE (300) and the network device (400), and there is also bidirectional communication between them. In the following, the transmitter is labeled 100 and the receiver is labeled 200.

[0061] The transmitter (100) receives a first SDU / PDU of a PDU set from an upper layer of a device (e.g., a UE (300) or a network device (400) etc.) at a PDCP entity. Upon receiving the first SDU / PDU at the PDCP entity, the transmitter (100) starts an XR discard timer for the PDU set.

[0062] In an embodiment, the transmitter (100) receives an XR radio bearer configuration in a radio resource control (RRC) signaling from a network device (400) (e.g., an eNB, a gNB, etc.). The XR radio bearer configuration includes at least one of an XR discard timer configuration and a PDU set integration processing indication (or may be referred to as a PDU set discard indication of a PDCP entity), the PDU set integration processing indication indicating whether the PDU set is allowed to be discarded at the transmitter (100). In addition, the transmitter (100) starts an XR discard timer for the PDU set when a first SDU / PDU is received at the PDCP entity. In another embodiment, the transmitter (100) receives the XR radio bearer configuration from the network device (400). In addition, when a corresponding SDU / PDU of the PDU set is received at the PDCP entity, the transmitter (100) starts an XR discard timer for the SDU / PDU of the PDU set.

[0063] Furthermore, the transmitter (100) maps a first SDU / PDU of the PDU set to an XR discard timer. Furthermore, the transmitter (100) stores the first SDU / PDU of the PDU set at a PDCP buffer (not shown). Furthermore, the transmitter (100) receives a subsequent SDU / PDU belonging to the same PDU set from an upper layer of the device at a PDCP entity. Furthermore, the transmitter (100) detects whether the XR discard timer for the PDU set expires.

[0064] In an embodiment, when an XR discard timer for a first SDU / PDU of a PDU set expires, the transmitter (100) discards subsequent SDU / PDUs of the PDU set, wherein the subsequent SDU / PDUs of the PDU set have been received at a PDCP entity, or the discarding is completed when the subsequent SDU / PDUs of the PDU set are received at the PDCP entity. In another embodiment, when an XR discard timer for a first SDU / PDU of a PDU set has not expired when the subsequent SDU / PDUs of the PDU set are received at the PDCP entity, the transmitter (100) maps the subsequent SDU / PDUs of the PDU set to the XR discard timer of each SDU / PDU. In addition, the transmitter (100) stores the subsequent SDU / PDUs of the PDU set at a PDCP buffer.

[0065] In an example, a transmitting PDCP entity and / or a receiving PDCP entity catering to an XR service or an XR radio bearer is mapped to (multiple) XR logical channels (e.g., referred to as an XR control channel XRCCH and / or an XR traffic channel XRTCH). The functionality of the PDCP entity for XR (or XR bearer) may be the same or different from that of the PDCP entity for a dedicated control channel (DCCH) / dedicated traffic channel (DTCH) logical channel for unicast. For example, if the XR service is already encrypted, the encryption / decryption functionality may not be configured for the XR bearer (or empty encryption may be configured). In addition, the PDCP entity for XR may be associated with one or more unacknowledged mode (UM) and / or acknowledged mode (AM) RLC entities.

[0066] In an embodiment, a timer referred to as XRdiscardTimer is configured for an XR radio bearer (referred to as XR-RB) for each XR frame (instead of each PDCP SDU). That is, an XRdiscardTimer is associated with an XR frame (i.e., a PDU set), and each PDCP SDU of a frame is associated with the same XRdiscardTimer. When the XRdiscardTimer expires for a frame or successful delivery of a frame is confirmed by a PDCP status report (i.e., successful delivery of each of the PDCP SDUs constituting the frame), the transmitting PDCP entity may discard the frame (i.e., each of the PDCP SDUs constituting the frame or PDU set). This Figure 6 Shown in.

[0067] In an embodiment, the PDCP entity is configured with multiple discard timer values ​​for different frame types, and the transmitting PDCP entity starts the timer with an appropriate discard timer value based on the type of frame to which the SDU is associated. For example, frame types (or PDU set types) may differ in their priority, importance, QoS parameters, content category (e.g., I, P, or B frames to which they apply), etc.

[0068] In an embodiment, when the transmitting PDCP entity receives the first PDCP SDU (i.e., IP packet) constituting a frame or a PDU set from upper layer(s), an XRdiscardTimer (if configured) is started. Furthermore, when subsequent (multiple) PDCP SDUs (i.e., second SDU, third SDU, ...) constituting a frame or a PDU set are received, the XRdiscardTimer operation is not affected (i.e., the timer keeps running). Furthermore, subsequent (multiple) PDCP SDUs constituting a frame or a PDU set are linked with the same XRdiscardTimer (if configured).

[0069] In one embodiment, if the XRdiscardTimer for a frame or PDU set has expired, and subsequently, the transmitting PDCP entity receives additional PDCP SDU(s) (i.e., IP packet(s)) from upper layers, the transmitting PDCP entity discards the received PDCP SDU(s) and does not store them in a buffer or transmit them. The following is a sample description of the changes to the transmit operation at the PDCP entity introduced to support the frame level XR discard timer:

[0070] Upon receiving a PDCP SDU from upper layers, if the PDCP entity is associated with an XR bearer, then when the PDCP SDU is the first segment associated with an XR frame or PDU set, as indicated by the "F" field, the PDCP entity starts the XRdiscardTimer associated with the frame or PDU set (if configured). Otherwise, the PDCP entity starts the discardTimer associated with the PDCP SDU (if configured).

[0071] In one embodiment, the network device (400) configures the XR radio bearer with XRdiscardTimer via RRC signaling (e.g., RRC reconfiguration carries RadioBearerConfig consisting of XRdiscardTimer for XR RBs). Configuration of XRdiscardTimer may be provided instead of or in addition to the traditional discardTimer configuration (for each SDU discard).

[0072] In an embodiment, the legacy discardTimer (used for each SDU discard) acts as an XRdiscardTimer when configured for an XR radio bearer. In an embodiment, the legacy discardTimer acts as a frame level discard timer for an XR radio bearer instead of an SDU discard timer. That is, the discardTimer is operated per SDU, and the timer is started when an SDU related to a PDU set is received from an upper layer at the PDCP entity. When the discardTimer expires, all SDUs / PDUs of the PDU set are discarded to achieve frame level discard.

[0073] In an embodiment, when upper layers request PDCP SDU discard for XR (i.e., request frame discard), the transmitting PDCP entity may discard all stored PDCP SDUs and PDCP PDUs associated with the frame or PDU set. In an alternative embodiment, when upper layers request PDCP SDU discard for XR, the transmitting PDCP entity may discard all stored PDCP SDUs and PDCP PDUs.

[0074] In an embodiment, the UE (300) is configured and / or signaled by the network device (400) for frame-based (i.e., PDU-set-based) SDU discard and / or an indication of whether to discard the entire frame if one or more SDUs constituting the frame are discarded (e.g., upon expiration of a discardTimer or XRdiscardTimer). Figure 7 Alternatively, the network device (400) may configure a threshold (eg, a number or percentage of constituent SDUs of a frame that, if discarded, would cause the UE (300) to discard the entire frame or set of PDUs).

[0075] When one or more PDCP SDUs related to the discarded frame (i.e., PDU set) have been associated with a PDCP sequence number (SN), there may be an SN gap in the transmitted PDCP PDUs, and the SN gap may cause an increase in the PDCP reordering delay in the receiving PDCP entity. In one embodiment, to overcome the above-mentioned increased reordering delay problem, the UE (300) continues the (multiple) PDCP data PDUs of the frame that have been assigned SNs, but still discards the PDCP SDUs of the frame that have not been assigned SNs. In addition, the first PDCP SDU of the next frame is assigned the next sequential SN that has not been assigned. At the receiving PDCP side, in order to know that there is a discard of the PDCP SDU of the frame and the PDCP SN is still in sequence (i.e., without any SN gap), the PDCP header of the first PDCP PDU of the next frame carries an indication field or bit or bitmap to indicate the earlier frame discard. The receiving PDCP entity may discard or remove the received PDCP SDUs of the incompletely received XR frame (i.e., PDU set) and continue processing the next XR frame. In an embodiment, the number of discarded XR frames may be one or more at the transmitting PDCP entity, and correspondingly, one or more at the receiving PDCP entity upon reordering.

[0076] In an embodiment, the upper layer indicates to the PDCP sending entity at least one of the following: the start of an XR frame (i.e., a PDU set) with the first PDCP SDU or IP packet provided, the end of an XR frame with the last PDCP SDU or IP packet provided, the size of the frame (or the number of constituent SDUs, the number of bytes), the sequence number, the priority, and the QoS information of the frame (i.e., a PDU set). The PDCP entity performs bookkeeping (e.g., maintains one or more variables) to track the XR frame start and / or frame end mapped to the corresponding (multiple) PDCP SDUs.

[0077] In an embodiment, all (multiple) PDCP SDUs related to a frame (ie a set of PDUs) are assigned the same sequence number value. The transmitting side RLC entity indicates successful transmission of the SDUs only after all (multiple) SDUs have been successfully delivered.

[0078] In an embodiment, in addition to the PDCP SN, the transmitting PDCP entity also sends the sequence number (i.e., position) of the SDU in the frame (i.e., the subsequence number - SSN of the SDU to indicate its position in the frame). The last SDU in a frame (i.e., a set of PDUs) may have a special value to indicate the end of the frame. In an embodiment, an end marker may be provided along with the position of the last SDU in the frame.

[0079] In an embodiment, the receiving PDCP entity uses the SSNs of the SDUs in the frame to perform reordering of the SDUs belonging to the same frame (ie, PDU set).

[0080] In an embodiment, the receiving PDCP entity may also be configured with a discard timer (frame level discard timer), and when the timer expires, the receiving PDCP entity discards all SDUs (ie, a PDU set) in the frame.

[0081] In an embodiment, the receiving PDCP entity may be configured with a frame level reordering timer, and when the frame level reordering timer expires, all SDUs belonging to a frame (ie, a PDU set) are discarded or delivered to upper layers.

[0082] In an embodiment, the receiving PDCP entity may be configured with a frame level indication for whether in-sequence delivery is required, i.e., the receiving PDCP entity may be configured with frame level out of order delivery separate from the legacy (SDU level) out of order delivery in current NR systems.

[0083] In an embodiment, if all SDUs associated with a frame (ie, a PDU set) are received in the PDCP receive buffer, the receiving PDCP entity may be configured to deliver to the upper layer without waiting for the reordering timer to expire.

[0084] In another embodiment, the receiving PDCP entity may be configured to deliver SDUs related to a frame (ie, a set of PDUs) to the upper layer only when all SDUs associated with the frame are received, so as to provide frame level delivery instead of the traditional SDU level delivery mechanism.

[0085] In an embodiment, frame information (e.g., start SDU, end SDU, number of SDUs, SDU sequence number, frame type (e.g., I frame (intra-coded frame) / P frame (predicted frame) / B frame (bidirectionally predicted frame)), priority, importance, QoS information) is provided to be embedded in a packet or packet header, where an I frame holds a complete frame, a P frame holds only a change from a previous frame, and a B frame holds the difference between the current frame and both the previous frame and the next frame to specify its content. That is, the frame (i.e., PDU set) information is marked / signaled in the header of the received upper layer packet (e.g., IP packet, RTP / SRTP / TCP / UDP packet, etc.). The same applies to the UE (300) and / or the network device (400).

[0086] In an embodiment, a PDCP entity setting field or bit or bitmap (e.g., in a PDCP header) is sent to indicate the start of an XR frame (i.e., a PDU set) in a PDCP SDU, which is the first PDCP SDU carrying an XR frame. In an alternative embodiment, a PDCP entity setting field or bit or bitmap (e.g., in a PDCP header) is sent to indicate the end of an XR frame in a PDCP SDU, which is the last PDCP SDU carrying an XR frame. In addition, the field may also include an indication of the continuation of a frame in a header related to a received PDCP SDU. For example, a field or bitmap referred to as "F" is set to 00 to indicate a continuous frame (i.e., an intermediate SDU) in the current SDU, is set to 01 to indicate the start of a frame in the current SDU and continues in the next SDU, is set to 10 to indicate the continuation from the previous SDU and the end of the frame in the current SDU, and is set to 11 to indicate both the start and end of the frame in the current SDU (i.e., only one SDU forms a frame).

[0087] In an embodiment, the receiving PDCP entity determines that the received frame is incomplete when processing (multiple) PDCP PDUs received in sequence (e.g., a new frame starts in the current SN PDCP PDU in the F field in the PDCP header, but the end of the last frame is not indicated by the F field in the PDCP header in the immediately preceding SN PDCP PDU). The receiving PDCP entity may discard or remove the received PDCP SDUs of the incompletely received XR frame (i.e., PDU set) and continue processing the next XR frame.

[0088] In an embodiment, the discarding or removal of incompletely received XR frames (i.e., PDU sets) is handled by the (multiple) upper layers rather than by the PDCP entity. That is, the PDCP entity still delivers the (multiple) PDCP SDUs related to the incompletely received XR frames to the (multiple) upper layers. In addition, the PDCP may additionally indicate to the (multiple) upper layers an indication for the incompletely received frames.

[0089] In addition, when the receiving PDCP entity receives a field or bit or bitmap in a PDCP SDU indicating the start (and / or end) of an XR frame (i.e., PDU set), it uses this information to reorder the XR frames or to compose PDCP SDUs and / or to deliver the XR frames or the composed PDCP SDUs to the upper layer (also shown in Fig. 9 ). For example, when the reordering timer t-Reordering expires, the operation of the receiving PDCP entity is described as follows (also shown in Fig.10 ).

[0090] When t-Reordering expires, the receiving PDCP entity shall:

[0091] After performing header decompression (if not decompressed previously), deliver the following to the upper layer in ascending order of the associated COUNT (count) values:

[0092] All stored (multiple) PDCP SDUs related to completely received frames with associated (multiple) COUNT values < RX_REORD;

[0093] All stored (multiple) PDCP SDUs related to completely received frames with consecutive associated (multiple) COUNT values starting from RX_REORD;

[0094] Discard all stored (multiple) PDCP SDUs related to incompletely received frames with associated (multiple) COUNT values < RX_REORD;

[0095] Update RX_DELIV to the COUNT value of the first PDCP SDU not yet delivered to the upper layer, where the COUNT value >= RX_REORD;

[0096] - If RX_DELIV < RX_NEXT:

[0097] - Update RX_REORD to RX_NEXT;

[0098] - Start t-Reordering.

[0099] In an embodiment, PDCP duplication is employed for XR. In addition, PDCP duplication is selectively configured and / or utilized for one or more XR streams / substreams / bearers or PDU sets or frame types (e.g., I / P / B frames) related to the same XR service. In addition, for XR RBs, when pdcp-duplicationd is configured (or deconfigured), the transmitting PDCP entity activates (or deactivates) PDCP duplication for the XR RB from the first PDCP SDU of the XR frame. In an embodiment, PDCP may be configured with the type of frames to which selective duplication is applied. The following is a sample description of the changes introduced in the PDCP transmitting entity operation to support selective duplication:

[0100] When submitting a PDCP PDU to lower layers, the transmitting PDCP entity shall:

[0101] If the transmitting PDCP entity is associated with an RLC entity:

[0102] Submitting the PDCP PDU to the associated RLC entity;

[0103] Otherwise, if the transmitting PDCP entity is associated with at least two RLC entities:

[0104] If PDCP duplication is activated for RB:

[0105] If the PDCP PDU is a PDCP data PDU:

[0106] If the PDCP entity is associated with an XR bearer and selective replication is configured:

[0107] If the PDCP data PDU corresponds to a frame type that is configured for duplication:

[0108] duplicating the PDCP data PDUs and submitting the PDCP data PDUs to the associated RLC entity activated for PDCP duplication;

[0109] otherwise

[0110] duplicating the PDCP data PDUs and submitting the PDCP data PDUs to the associated RLC entity activated for PDCP duplication;

[0111] otherwise:

[0112] Submitting PDCP control PDU to the primary RLC entity;

[0113] In an embodiment, when an upper layer requests the PDCP entity to re-establish the first PDCP SDU for which the lower layer has not yet confirmed successful delivery of the corresponding PDCP data PDU for the AM DBR of the Uu interface of the XR in which the PDCP entity is suspended, for each PDCP SDU that has been associated with the PDCP SN, the transmitting PDCP entity of the XR performs transmission of the PDCP SDUs in ascending order of the COUNT values ​​associated with the PDCP XR frames (i.e., PDU sets) before the PDCP re-establishment without restarting the XRdiscardTimer.

[0114] In an embodiment, when the upper layer requests the PDCP entity to reestablish (if the XRdiscardTimer is still running) the first PDCP SDU for which the lower layer has not yet confirmed the successful delivery of the corresponding PDCP data PDU for the AM DBR of the Uu interface of the XR in which the PDCP entity is suspended, for each PDCP SDU that has been associated with the PDCP SN, the transmitting PDCP entity of the XR performs transmission of the PDCP SDUs in ascending order of the COUNT values ​​associated with the PDCP XR frames (i.e., PDU sets) before the PDCP reestablishment without restarting the XRdiscardTimer. If the xrDiscardTimer expires, the transmitting PDCP entity of the XR does not perform transmission of the PDCP SDUs.

[0115] In an embodiment, when the upper layer requests the PDCP entity to reestablish the first PDCP SDU for which the lower layer has not yet confirmed the successful delivery of the corresponding PDCP data PDU for the AM DBR of the XR whose PDCP entity is not suspended, the sending PDCP entity of the XR performs retransmission or transmission of all PDCP SDUs already associated with the PDCP SN in ascending order of the COUNT values ​​associated with the PDCP SDUs before the PDCP entity reestablishment, assuming that the XRdiscardTimer is still running.

[0116] In an embodiment, when upper layers request the PDCP entity to reestablish, the receiving PDCP entity of the XR UM mode radio bearer stops and resets the t-Reordering timer (if running). In addition, after performing header decompression (if configured), the receiving PDCP entity delivers all stored (multiple) PDCP SDUs to upper layers in ascending order of associated COUNT values.

[0117] In an embodiment, when upper layers request the PDCP entity to reestablish, the receiving PDCP entity of the XR UM mode radio bearer stops and resets the t-Reordering timer (if running). Furthermore, after performing header decompression (if configured), it delivers only those stored (multiple) PDCP SDUs that form a complete XR frame (i.e., a PDU set) to upper layers in ascending order of the associated COUNT values.

[0118] In an embodiment, when the upper layers request the release of the PDCP entity for the XR radio bearer, the UE (300) may discard all stored PDCP SDUs and PDCP PDUs in the sending PDCP entity. In addition, for (multiple) XR radio bearers, assuming that all constituent SDUs of the XR frame (i.e., PDU set) are received, the UE (300) may deliver the PDCP SDUs stored in the receiving PDCP entity to the upper layers in ascending order of the associated COUNT value after performing header decompression (if previously configured and not decompressed). In addition, the UE (300) may release the PDCP entity for the XR radio bearer.

[0119] In an embodiment, when the upper layers request the PDCP entity to pause, if t-Reordering is running, the receiving PDCP entity stops and resets t-Reordering. In addition, assuming that all constituent SDUs of an XR frame (i.e., a PDU set) are received, it delivers all stored PDCP SDUs to the upper layers in ascending order of the associated COUNT values ​​after performing header decompression. In addition, it sets RX_NEXT and RX_DELIV to initial values.

[0120] In an embodiment, when upper layers reconfigure the PDCP entity to configure a dual active protocol stack (DAPS) and / or release the DAP, the timer XRdiscardTimer continues, ie the timer keeps running during the PDCP entity reconfiguration procedure.

[0121] In an embodiment, the procedure for managing received PDCP data PDUs at a receiving PDCP entity of an XR radio bearer is described as follows (in Figure 3 same as shown in ).

[0122] If a received PDCP data PDU with COUNT value = RCVD_COUNT is not discarded (e.g. integrity failure, duplicate), the receiving PDCP entity shall:

[0123] storing the obtained PDCP SDU in a receiving buffer;

[0124] If RCVD_COUNT>=RX_NEXT:

[0125] - Update RX_NEXT to RCVD_COUNT+1.

[0126] If frameoutOfOrderDelivery is configured:

[0127] - A frame is considered completely received if all byte segments of the corresponding frame are received in the receive buffer:

[0128] - After performing header decompression, all (multiple) PDCP SDUs associated with the complete frame are delivered to upper layers.

[0129] - Update RX_DELIV to the COUNT value of the first PDCP SDU that has not been delivered to the upper layer, where COUNT value > RX_DELIV;

[0130] Otherwise, if outofOrderDelivery is configured:

[0131] After performing header decompression using EHC (if configured), the resulting PDCP SDU is delivered to upper layers.

[0132] If RCVD_COUNT=RX_DELIV:

[0133] - if not previously decompressed, the following items are delivered to upper layers in ascending order of associated count values ​​after performing header decompression (if configured);

[0134] - all stored PDCP SDU(s) with consecutively associated COUNT value(s) starting from COUNT=RX_DELIV, assuming that they relate to completely received frames if frameDeliveryAllowed is configured and / or set to TRUE; or

[0135] - if frameDeliveryAllowed is not configured and / or set to FALSE, all stored PDCP SDU(s) with consecutive associated COUNT value(s) starting from COUNT=RX_DELIV;

[0136] - Update RX_DELIV to the COUNT value of the first PDCP SDU that has not been delivered to the upper layer, where COUNT value > RX_DELIV;

[0137] If t-Reordering is running, and if RX_DELIV>=RX_REORD:

[0138] - Stop and reset t-Reordering.

[0139] If t-Reordering is not running (including the case when t-Reordering is stopped due to the above actions), and RX_DELIV <RX_NEXT:

[0140] - Update RX_REORD to RX_NEXT;

[0141] -Start t-Reordering.

[0142] In an embodiment, the configuration of the XR bearer is carried in the RRCReconfiguration message as part of the PDCP configuration or separately as part of the XRBearerConfiguration.

[0143] The following is a sample ASN structure of PDCPConfig containing XR bearer related PDCP layer configuration:

[0144]

[0145]

[0146]

[0147]

[0148] The field description is shown in Table 1:

[0149] Field Description

[0150] The isXRBearerisXRBearer field indicates whether the PDCP entity belongs to an XR radio bearer. The isXRBearer field is set when an XR bearer is set.

[0151] XRdiscardTimerXRdiscardTimer indicates the value in ms of the XRdiscardTimer used for XR, if configured.

[0152] The t-ReorderingXR field indicates the value of t-ReorderingXR in milliseconds for frame level reordering of XR, if configured.

[0153] frameDiscardAllowed If included, this field indicates that PDCP performs frame level discard (i.e., PDU set based discard) at the transmitter side if one or more constituent PDCP SDUs of a frame (i.e., PDU set) are discarded.

[0154] frameOutOfOrderDelivery If included, this field indicates whether the PDCP receiving entity delivers the SDUs of the received frame(s) out of order with respect to the frame number.

[0155] frameDeliveryAllowedThe frameDeliveryAllowed field instructs the PDCP receiver to deliver the received SDUs to the upper layer at the frame level by waiting until all SDUs of a frame (ie, a PDU set) are received.

[0156] The useSSNperFrame field instructs PDCP to use the Sub-Sequence Number (SSN) to indicate the position of the SDU within a frame. When configured, all SDUs of a single frame will be assigned the same SN and individually identified based on the SSN.

[0157] If selectiveDuplicationSupp-ort is configured, when PDCP duplication is enabled and activated, PDCP performs duplication only on the configured high priority frame PDUs.

[0158] Table-1

[0159] Figure 2 Various hardware components of a transmitter (100) according to an embodiment disclosed herein are shown. In an embodiment, the transmitter (100) includes a processor (110), a communicator (120), a memory (130), and a PDCP discard controller (140). The processor (110) is coupled to the communicator (120), the memory (130), and the PDCP discard controller (140).

[0160] The PDCP discard controller (140) receives a first SDU / PDU of a PDU set from an upper layer entity of a device at a PDCP entity. Upon receiving the first SDU / PDU at the PDCP entity, the PDCP discard controller (140) starts an XR discard timer for the PDU set.

[0161] In an embodiment, the PDCP discard controller (140) receives an XR radio bearer configuration in a radio resource control (RRC) signaling from a network device (400). The XR radio bearer configuration includes at least one of an XR discard timer configuration and a PDU set integration processing indication (or may be referred to as a PDU set discard indication of a PDCP entity), the PDU set integration processing indication indicating whether the PDU set is allowed to be discarded at the transmitter (100). In addition, the PDCP discard controller (140) starts the XR discard timer for the PDU set when a first SDU / PDU is received at the PDCP entity. In another embodiment, the PDCP discard controller (140) receives the XR radio bearer configuration from the network device (400). In addition, the PDCP discard controller (140) starts the XR discard timer for the SDU / PDU of the PDU set when a corresponding SDU / PDU of the PDU set is received at the PDCP entity.

[0162] Furthermore, the PDCP discard controller (140) maps a first SDU / PDU of the PDU set to an XR discard timer. Furthermore, the PDCP discard controller (140) stores the first SDU / PDU of the PDU set at a PDCP buffer. Furthermore, the PDCP discard controller (140) receives, at a PDCP entity, subsequent SDU / PDUs belonging to the same PDU set from an upper layer entity of the device.

[0163] Furthermore, the PDCP discard controller (140) detects whether an XR discard timer for the PDU set expires.

[0164] In an embodiment, when an XR discard timer for a first SDU / PDU of a PDU set expires, the PDCP discard controller (140) discards subsequent SDU / PDUs of the PDU set, wherein the subsequent SDU / PDUs of the PDU set have been received at the PDCP entity, or the discarding is completed when at least one subsequent SDU / PDU of the PDU set is received at the PDCP entity. In another embodiment, when an XR discard timer for a first SDU / PDU of a PDU set has not expired when the subsequent SDU / PDU of the PDU set is received at the PDCP entity, the PDCP discard controller (140) maps the subsequent SDU / PDU of the PDU set to the XR discard timer of each SDU / PDU. In addition, the PDCP discard controller (140) stores the subsequent SDU / PDU of the PDU set at the PDCP buffer.

[0165] Furthermore, the PDCP discard controller (140) detects expiration of an XR discard timer for a PDU set or loss of at least one SDU / PDU constituting the PDU set or successful delivery of all SDU / PDU constituting the PDU set. Furthermore, when the XR discard timer for a PDU set expires or loss of at least one SDU / PDU constituting the PDU set is detected or successful delivery of all SDU / PDU constituting the PDU set is detected, the PDCP discard controller (140) discards a PDU set including a first SDU / PDU mapped to the XR discard timer for the PDU set and subsequent SDU / PDUs.

[0166] Furthermore, the PDCP discard controller (140) detects expiration of an XR discard timer for at least one SDU / PDU of the PDU set or loss of at least one SDU / PDU constituting the PDU set or successful transmission of all SDU / PDU constituting the PDU set. Furthermore, when the XR discard timer for at least one SDU / PDU of the PDU set expires or loss of at least one SDU / PDU constituting the PDU set is detected or successful transmission of all SDU / PDU constituting the PDU set is detected, the PDCP discard controller (140) discards the PDU set including the first SDU / PDU of the PDU set and subsequent SDU / PDUs.

[0167] Furthermore, the PDCP discard controller (140) adds at least one of a frame start indication indicating a first SDU / PDU of a PDU set, a frame continuation indication indicating a subsequent SDU / PDU of the PDU set, and a frame end indication indicating a last SDU / PDU of the PDU set in a PDCP header in each SDU / PDU. Furthermore, the PDCP discard controller (140) transmits at least one of the first SDU / PDU and the subsequent SDU / PDU belonging to the same PDU set to the receiver (200).

[0168] A first SDU / PDU and subsequent SDU / PDUs of a PDU set are discarded by detecting whether a PDU set integration processing indication indicates that discarding of the PDU set is allowed at the transmitter (100), and one of the following: discarding the first SDU / PDU and subsequent SDU / PDUs of the PDU set when the PDU set integration processing indication indicates that discarding of the PDU set is allowed at the transmitter (100), or discarding the corresponding SDU / PDU when the PDU set integration processing indication indicates that discarding of the PDU set is not allowed at the transmitter (100).

[0169] The PDCP discard controller (140) is implemented by analog and / or digital circuits (such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hard-wired circuits, etc.) and may optionally be driven by firmware.

[0170] In addition, the processor (110) is configured to execute instructions stored in the memory (130) and perform various processes. The communicator (120) is configured to communicate internally between internal hardware components and with external devices via one or more networks. The memory (130) also stores instructions to be executed by the processor (110). The memory (130) may include a non-volatile storage element. Examples of such non-volatile storage elements may include a magnetic hard disk, an optical disk, a floppy disk, a flash memory, or a form of an electrically programmable memory (EPROM) or an electrically erasable programmable (EEPROM) memory. In addition, in some examples, the memory (130) may be considered a non-transitory storage medium. The term "non-transitory" may indicate that the storage medium is not embodied in a carrier or propagating signal. However, the term "non-transitory" should not be interpreted as the memory (130) being non-removable. In some instances, a non-transitory storage medium may store data that may change over time (e.g., in a random access memory (RAM) or a cache memory).

[0171] although Figure 2 Various hardware components of the transmitter (100) are shown, but it should be understood that other embodiments are not limited thereto. In other embodiments, the transmitter (100) may include fewer or greater numbers of components. In addition, the labels or names of the components are for illustrative purposes only and do not limit the scope of the present invention. One or more components may be combined together to perform the same or substantially similar functions in the transmitter (100).

[0172] Figure 3 Various hardware components of a receiver (200) according to an embodiment disclosed herein are shown. In an embodiment, the receiver (200) includes a processor (210), a communicator (220), a memory (230), and a PDCP discard controller (240). The processor (210) is coupled to the communicator (220), the memory (230), and the PDCP discard controller (240).

[0173] The PDCP discard controller (240) receives an XR radio bearer configuration in a radio resource control (RRC) signaling from a network device (400). The XR radio bearer configuration includes a frame delivery permission indication indicating whether a completely received PDU set is allowed to be delivered from a receiver (200). In addition, the PDCP discard controller (240) receives a plurality of SDUs / PDUs belonging to the PDU set, wherein a PDCP header in each SDU / PDU includes a frame start indication indicating a first SDU / PDU of the PDU set, a frame continuation indication indicating a subsequent SDU / PDU of the PDU set, and a frame end indication indicating a last SDU / PDU of the PDU set. In addition, the PDCP discard controller (240) detects whether a frame delivery permission indication indicating that the PDU / SDU is allowed to be delivered from the receiver (200) is configured.

[0174] In an embodiment, when a frame delivery allow indication indicating that a completely received PDU set is allowed to be delivered from a receiver (200) is configured, a PDCP discard controller (240) delivers a plurality of SDUs / PDUs belonging to a PDU set to an upper layer entity after receiving the complete PDU set.

[0175] In another embodiment, when a frame delivery allow indication indicating that a completely received PDU set is allowed to be delivered from the receiver (200) is not configured, the PDCP discard controller (240) reorders a plurality of SDUs / PDUs belonging to the PDU set based on a PDCP header of the SDUs / PDUs. In addition, the PDCP discard controller (240) delivers each of the plurality of SDUs / PDUs belonging to the PDU set to an upper layer entity based on expiration of a reordering timer.

[0176] In an embodiment, the PDCP discard controller (240) decompresses the PDCP header based on at least one of: all stored SDUs / PDUs related to a complete received PDU set having an associated COUNT value less than RX_REORD, and all stored SDUs / PDUs related to a complete received PDU set having an associated COUNT value starting from RX_REORD. RX_REORD indicates a COUNT value after the COUNT value associated with the PDCP data PDU that triggered the reordering timer. In addition, the PDCP discard controller (240) discards all stored SDUs / PDUs related to an incomplete received PDU set having an associated (multiple) COUNT value less than RX_REORD. In addition, the PDCP discard controller (240) delivers each of the multiple SDUs / PDUs belonging to the complete received PDU set to an upper layer entity in ascending order of the associated COUNT value. In addition, the PDCP discard controller (240) updates RX_DELIV to a COUNT value of the first SDU / PDU that has not been delivered to the upper layer, wherein the COUNT value is greater than or equal to RX_REORD, wherein RX_DELIV indicates the COUNT value of the first PDCP SDU that has not been delivered to the upper layer. In addition, if RX_DELIV is less than RX_NEXT, the PDCP discard controller (240) updates RX_REORD to RX_NEXT and starts a reordering timer, wherein RX_NEXT indicates the COUNT value of the next PDCP SDU expected to be received.

[0177] The PDCP discard controller (240) is implemented by analog and / or digital circuits (such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hard-wired circuits, etc.) and may optionally be driven by firmware.

[0178] In addition, the processor (210) is configured to execute instructions stored in the memory (230) and perform various processes. The communicator (220) is configured to communicate internally between internal hardware components and with external devices via one or more networks. The memory (230) also stores instructions to be executed by the processor (210). The memory (230) may include a non-volatile storage element. Examples of such non-volatile storage elements may include a magnetic hard disk, an optical disk, a floppy disk, a flash memory, or a form of an electrically programmable memory (EPROM) or an electrically erasable programmable (EEPROM) memory. In addition, in some examples, the memory (230) may be considered a non-transitory storage medium. The term "non-transitory" may indicate that the storage medium is not embodied in a carrier or propagating signal. However, the term "non-transitory" should not be interpreted as the memory (230) being non-removable. In some instances, a non-transitory storage medium may store data that may change over time (e.g., in a random access memory (RAM) or a cache memory).

[0179] although Figure 3 Various hardware components of the receiver (200) are shown, but it should be understood that other embodiments are not limited thereto. In other embodiments, the receiver (200) may include fewer or greater numbers of components. In addition, the labels or names of the components are for illustrative purposes only and do not limit the scope of the present invention. One or more components may be combined together to perform the same or substantially similar functions in the receiver (200).

[0180] Figure 4 is a flow chart (S400) illustrating a method implemented by a transmitter (100) for discarding PDCP packets for XR in a wireless network (1000) according to an embodiment disclosed herein. Operations (S402-S418) are processed by a PDCP discard controller (140).

[0181] At S402, the method includes receiving a first SDU / PDU of a PDU set from an upper layer entity of the device at a PDCP entity. At S404, the method includes starting an XR discard timer for the PDU set when the first SDU / PDU is received at the PDCP entity. At S406, the method includes mapping the first SDU / PDU of the PDU set to the XR discard timer. At S408, the method includes storing the first SDU / PDU of the PDU set at a PDCP buffer. At S410, the method includes receiving a subsequent SDU / PDU belonging to the same PDU set from an upper layer entity of the device at the PDCP entity. At S412, the method includes detecting whether the XR discard timer for the PDU set has expired.

[0182] In an embodiment, at S414, the method includes discarding subsequent SDUs / PDUs of the PDU set when an XR discard timer for a first SDU / PDU of the PDU set expires, wherein the discarding is completed when at least one subsequent SDU / PDU of the PDU set has been received at the PDCP entity or at least one subsequent SDU / PDU of the PDU set is received at the PDCP entity. In another embodiment, at S416, the method includes: when the XR discard timer for the first SDU / PDU of the PDU set has not expired when the subsequent SDU / PDU of the PDU set is received at the PDCP entity, mapping the subsequent SDU / PDU of the PDU set to the XR discard timer of each SDU / PDU. At S418, the method includes storing the subsequent SDU / PDU of the PDU set at the PDCP buffer.

[0183] Figure 5 is a flow chart (S500) illustrating a method implemented by a receiver (200) for discarding PDCP packets for XR in a wireless network (1000) according to an embodiment disclosed herein. Operations (S502-S512) are processed by a PDCP discard controller (240).

[0184] At S502, the method includes receiving an XR radio bearer configuration in a radio resource control (RRC) signaling from a network device (400). The XR radio bearer configuration includes a frame delivery allow indication indicating whether a complete received PDU set is allowed to be delivered from a receiver is configured. At S504, the method includes receiving a plurality of SDUs / PDUs belonging to the PDU set, wherein a PDCP header in each SDU / PDU includes at least one of a frame start indication indicating a first SDU / PDU of the PDU set, a frame continuation indication indicating a subsequent SDU / PDU of the PDU set, and a frame end indication indicating a last SDU / PDU of the PDU set. At S506, the method includes detecting whether a frame delivery allow indication indicating that a PDU / SDU is allowed to be delivered from a receiver (200) is configured. In an embodiment, at S508, the method includes: when a frame delivery allow indication indicating that a complete received PDU set is allowed to be delivered from a receiver (200) is configured, after receiving the complete PDU set, delivering the plurality of SDUs / PDUs belonging to the PDU set to an upper layer entity. In another embodiment, at S510, the method includes: when a frame delivery permission indication indicating that a completely received PDU set is allowed to be delivered from a receiver is not configured, reordering a plurality of SDUs / PDUs belonging to the PDU set based on a PDCP header of the SDUs / PDUs. At S512, the method includes delivering each of the plurality of SDUs / PDUs belonging to the PDU set to an upper layer entity based on the reordering.

[0185] Figure 6is a flow chart (S600) illustrating a PDCP discard mechanism at a transmitting PDCP entity for XR in a wireless network (1000) according to an embodiment disclosed herein. The operations (S602-S608) are processed with the assistance of a PDCP discard controller (140).

[0186] At S602, when the transmitting PDCP entity receives the first PDCP SDU constituting a frame (i.e., a set of PDUs) from an upper layer, the transmitting PDCP entity starts an XRdiscardTimer (if configured). At S604, the transmitting PDCP entity receives subsequent (multiple) SDUs constituting the frame from an upper layer, the timer (if running) is not affected, and the (multiple) SDUs are linked to the same timer. If the timer has expired, the transmitting PDCP entity discards the subsequent (multiple) SDUs. At S606, the method includes determining whether the XRdiscardTimer expires for the frame or successful delivery of the frame is confirmed by a PDCP status report?

[0187] In response to determining that XRdiscardTimer expires for the frame or that successful delivery of the frame is confirmed by the PDCP status report, at S608, the sending PDCP entity discards the frame (i.e., each of the PDCP SDUs constituting the frame, i.e., the PDU set). In response to determining that XRdiscardTimer has not expired for the frame or that the PDCP status report confirms successful delivery of the frame, the method performs operation S606.

[0188] Figure 7 The invention is a flow chart (S700) showing a PDCP discard mechanism at a transmitting PDCP entity for XR based on configuration parameters in a wireless network (1000) according to an embodiment disclosed herein. The operations (S702-S708) are processed with the assistance of a PDCP discard controller (140).

[0189] At S702 , the UE ( 300 ) receives an XR radio bearer configured with FrameDiscardAllowed and discardTimer and / or XRdiscardTimer in radiobearerconfig in RRC reconfiguration. At S704 , the method includes determining whether FrameDiscardAllowed is configured or set to TRUE?

[0190] In response to determining that FrameDiscardAllowed is configured or set to TRUE, then at S706, when XRdiscardTimer / discardTimer expires or successful delivery of the frame is confirmed by the PDCP status report, the sending PDCP entity discards the frame (i.e., the PDU set). In response to determining that FrameDiscardAllowed is not configured or set to FALSE, then at S708, when XRdiscardTimer / discardTimer expires or successful delivery of the PDCP SDU is confirmed by the PDCP status report, the sending PDCP entity discards the PDCP SDU.

[0191] Figure 8 1 is a flow chart (S800) illustrating a PDCP reordering and delivery mechanism at a receiving PDCP entity (i.e., a receiver (200)) for XR in a wireless network (1000) according to an embodiment disclosed herein. Operations (S802-S808) are processed with the assistance of a PDCP discard controller (240).

[0192] At S802 , the UE ( 300 ) receives an XR radio bearer configured with FrameDeliveryAllowed in radiobearerconfig in RRC reconfiguration. At S804 , the UE ( 300 ) determines whether FrameDeliveryAllowed is configured or set to TRUE?

[0193] In response to determining that FrameDeliveryAllowed is configured or set to TRUE, then at S806, the receiving PDCP entity delivers the (multiple) PDCP SDUs constituting the frame (i.e., the PDU set) upon receiving a complete frame (i.e., each (multiple) PDCP SDU of the frame). In response to determining that FrameDeliveryAllowed is not configured or set to FALSE, then at S808, the receiving PDCP entity delivers the (multiple) PDCP SDUs when the (multiple) SDUs are received in sequence or the reordering timer expires.

[0194] Fig. 9 is a flowchart ( S900 ) illustrating a method for transmitting frame-PDCP SDU mapping information for XR in a wireless network ( 1000 ) according to an embodiment disclosed herein.

[0195] At S902, the transmitting PDCP entity adds at least one of the indications in the PDCP header related to the PDCP SDUs of the frame (i.e., PDU set), where the indications include indicating the start of a frame for the first SDU, indicating the continuation of a frame for an intermediate SDU, and indicating the end of a frame for the last SDU. The indication can be one or more bits, a bitmap, a field, a code point, or an index. At S904, the receiving PDCP entity receives the (multiple) indications in the PDCP header of the (multiple) PDCP SDUs of the frame and uses them for reordering and / or delivering the frame. For example, the frame is delivered only when the frame is completely received.

[0196] Fig.10 Is a flowchart (S1000) showing a PDCP delivery mechanism for XR in a wireless network (1000) according to an embodiment disclosed herein when a reordering timer expires at a transmitting PDCP entity. Operations (S1002 - S1008) are handled by a PDCP discard controller (240).

[0197] At S1002, when the t-Reordering timer expires, the receiving PDCP entity delivers to the upper layer in ascending order of the associated COUNT value after performing header decompression (if not decompressed previously): all stored (multiple) PDCP SDUs with associated (multiple) COUNT values < RX_REORD related to a completely received frame, and all stored (multiple) PDCP SDUs with consecutive associated (multiple) COUNT values starting from RX_REORD related to a completely received frame.

[0198] At S1004, the receiving PDCP entity discards all stored (multiple) PDCP SDUs with associated (multiple) COUNT values < RX_REORD related to an incompletely received frame (i.e., PDU set). At S1006, the receiving PDCP entity updates RX_DELIV to the COUNT value of the first PDCP SDU that has not been delivered to the upper layer, where the COUNT value >= RX_REORD. At S1008, the receiving PDCP entity updates RX_REORD to RX_NEXT, and if RX_DELIV < RX_NEXT, starts the t-Reordering timer.

[0199] Figure 11-14 Shows various sample XR bearer data PDU formats (1100 - 1400) with one or more sequence numbers, frame indicator fields, and sub-sequence number fields according to an embodiment disclosed herein.

[0200] In an embodiment, Fig.11 Is a sample XR bearer data PDU format (1100) with a 12-bit sequence number and a 2-bit frame indicator field.

[0201] In an embodiment, Fig.12 is a sample XR bearer data PDU format (1200) with an 18-bit sequence number and a 2-bit frame indicator field.

[0202] Parameter F description, length: 2 bits, this field indicates the position of the PDCP SDU in the XR frame (i.e., PDU set), such as the start or end of the frame, and is used by the receiving entity to determine whether the entire frame has been completely received, as shown in Table 2.

[0203] Bit Description

[0204] 00 Continuous frame (middle SDU)

[0205] 01 The first SDU of the frame (the first segment of the frame)

[0206] The last SDU of 10 frames (the last segment of the frame)

[0207] 11 Entire frame without segment

[0208] Table-2 (Field F)

[0209] In an embodiment, Fig.13 is a sample XR bearer data PDU format (1300) with a 12-bit sequence number and a 7-bit frame sub-sequence number (SSN) field.

[0210] In an embodiment, Fig.14 is a sample XR bearer data PDU format (1400) with 18-bit sequence number and 7-bit frame sub-sequence number fields.

[0211] Parameter Frame SSN Description, length: 7 bits, this field indicates the position of the PDU in the XR frame by using the subsequence number. The receiving entity uses the frame SSN to reorder the SDUs within the frame.

[0212] The method provides efficient and effective PDCP discard operation, thereby ensuring timely delivery of packets and saving transmission resources for XR applications. As a result, UE (300) and network XR service performance is significantly increased with efficient transmission resource usage and lower latency.

[0213] The various actions, actions, blocks, steps, etc. in the flow chart (S400-S1000) may be performed in the order presented, in a different order, or simultaneously. In addition, in some embodiments, some of the actions, actions, blocks, steps, etc. may be omitted, added, modified, skipped, etc. without departing from the scope of the present invention.

[0214] The embodiments disclosed herein may be implemented using at least one hardware device and performing a network management function to control elements.

[0215] The foregoing description of specific embodiments will fully reveal the general nature of the embodiments herein so that others can easily modify and / or adjust such specific embodiments for various applications by applying current knowledge without departing from the general concepts, and therefore, such adjustments and modifications should and are intended to be understood as being within the meaning and scope of equivalents of the disclosed embodiments. It should be understood that the wording or terminology employed herein is for descriptive and not limiting purposes. Therefore, although the embodiments herein have been described according to preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced by modification within the scope of the embodiments as described herein.

Claims

1. A method performed by a transmitter in a wireless communication system, the method comprising: Receiving a Packet Data Convergence Protocol (PDCP) service data unit (SDU) from an upper layer; Based on the reception of the PDCP SDU, start an extended reality (XR) discard timer for a protocol data unit (PDU) set associated with the PDCP SDU, wherein the PDU set includes a PDCP PDU corresponding to the PDCP SDU; and When the XR discard timer expires, the PDCP PDUs of the PDU set are discarded.

2. The method according to claim 1, wherein: In case at least one PDCP PDU of the PDU set is lost, the PDCP PDU of the PDU set is discarded.

3. The method according to claim 1, wherein: The value of the XR discard timer is configured based on a radio resource control RRC message, wherein the value of the XR discard timer is associated with the type of the PDU set, and The RRC message includes a PDU set discard indication, and the PDU set discard indication indicates discarding all PDCP PDUs of the PDU set.

4. The method according to claim 1, wherein: A PDCP header of the PDCP PDU includes information associated with a start of the PDU set and information associated with an end of the PDU set.

5. A method performed by a receiver in a wireless communication system, the method comprising: receiving a packet data convergence protocol PDCP PDU in a protocol data unit PDU set from a transmitter; if a PDU set delivery indication is configured, identifying whether all PDCP PDUs of the PDU set are received based on a PDCP header of the PDCP PDU; and In a case where all the PDCP PDUs of the PDU set are received, PDCP service data units SDUs corresponding to all the PDCP PDUs of the PDU set are delivered to an upper layer.

6. The method according to claim 5, wherein: Receiving the PDCP PDU further includes: reordering the PDCP PDUs of the PDU set based on the PDCP header if the PDU set delivery indication is not configured; and A PDCP SDU corresponding to the PDCP PDU of the PDU set is delivered.

7. The method according to claim 5, wherein: The PDU set delivery indication is configured based on a radio resource control RRC message.

8. The method according to claim 5, wherein: The PDCP header includes information associated with a start of the PDU set and information associated with an end of the PDU set.

9. A device in a wireless communication system, the device comprising: Transceiver; and a controller coupled to the transceiver and configured to: Receiving a Packet Data Convergence Protocol (PDCP) service data unit (SDU) from an upper layer; Based on the reception of the PDCP SDU, start an extended reality (XR) discard timer for a protocol data unit (PDU) set associated with the PDCP SDU, wherein the PDU set includes a PDCP PDU corresponding to the PDCP SDU; and When the XR discard timer expires, the PDCP PDUs of the PDU set are discarded.

10. The device according to claim 9, wherein: In case at least one PDCP PDU in the PDU set is lost, the PDCP PDUs in the PDU set are discarded.

11. The device according to claim 9, wherein: The value of the XR discard timer is configured based on a radio resource control RRC message, wherein the value of the XR discard timer is associated with the type of the PDU set, and The RRC message includes a PDU set discard indication, and the PDU set discard indication indicates discarding all PDCP PDUs of the PDU set.

12. The device according to claim 9, wherein: A PDCP header of the PDCP PDU includes information associated with a start of the PDU set and information associated with an end of the PDU set.

13. A device in a wireless communication system, the device comprising: Transceiver; and a controller coupled to the transceiver and configured to: receiving a packet data convergence protocol PDCP PDU in a protocol data unit PDU set from a transmitter; if a PDU set delivery indication is configured, identifying whether all PDCP PDUs of the PDU set are received based on a PDCP header of the PDCP PDU; and In a case where all the PDCP PDUs of the PDU set are received, PDCP service data units SDUs corresponding to all the PDCP PDUs of the PDU set are delivered to an upper layer.

14. The apparatus of claim 13, wherein the controller is configured to: reordering the PDCP PDUs of the PDU set based on the PDCP header if the PDU set delivery indication is not configured, and A PDCP SDU corresponding to the PDCP PDU of the PDU set is delivered.

15. The device according to claim 13, wherein: The PDU set delivery indication is configured based on a radio resource control RRC message, and The PDCP header includes information associated with the start of the PDU set and information associated with the end of the PDU set.

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