Managing packet discard signalling for extended reality (XR) in a communication system

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. Embodiments disclosed herein describe a method and system for managing packet discard signalling for extended reality (XR) in a communication system. Further, includes a first electronic device (100) and second electronic device (200), each with a transmitting PDCP entity and receiving PDCP entity, each with a memory, a processor, and PDCP Sequence Number (SN) gap controller. The controller determines whether a triggering criteria is met at the transmitting PDCP entity, based on discarded or stored PDCP Service Data Units (SDUs). If the criteria are met, the first electronic device (100) triggers packet discard signaling to the second electronic device (200) for generating a PDCP SN gap report. The second electronic device (200) processes discard information for SDUs within the reordering window, while ignoring those outside the window. This enables efficient approach for packet discard signaling and achieving low-latency operations for XR.

Description

MANAGING PACKET DISCARD SIGNALLING FOR EXTENDED REALITY (XR) IN A COMMUNICATION SYSTEM

[0001] The present application relates to wireless communication and more specifically relates to managing packet discard signaling for Extended Reality (XR) in a communication system.

[0002] 5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in "Sub 6GHz" bands such as 3.5GHz, but also in "Above 6GHz" bands referred to as mmWave including 28GHz and 39GHz. In addition, it has been considered to implement 6G mobile communication technologies (referred to as Beyond 5G systems) in terahertz bands (for example, 95GHz to 3THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

[0003] At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive MIMO for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of BWP (BandWidth Part), new channel coding methods such as a LDPC (Low Density Parity Check) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

[0004] Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as V2X (Vehicle-to-everything) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR UE Power Saving, Non-Terrestrial Network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

[0005] Moreover, there has been ongoing standardization in air interface architecture / protocol regarding technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture / service regarding a 5G baseline architecture (for example, 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 positions.

[0006] As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

[0007] Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using OAM (Orbital Angular Momentum), and RIS (Reconfigurable Intelligent Surface), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI (Artificial Intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

[0008] The present invention has been made to address at least the above problems and / or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention provides a method and apparatus for managing packet discard signaling for extended reality (XR) in a communication system.

[0009] In accordance with an aspect of the disclosure, a method performed by a user equipment (UE) is provided. The method includes receiving, from a base station, a radio resource control (RRC) message for configuring a transmission of a packet data convergence protocol (PDCP) sequence number (SN) gap report; identifying whether to trigger a packet data convergence protocol (PDCP) sequence number (SN) gap report; and in case that the PDCP SN gap report is triggered, transmitting, to the base station, the PDCP SN gap report, wherein the PDCP SN gap report includes at least one of a first discarded count (FDC) field and a discard bitmap field.

[0010] In accordance with an aspect of the disclosure, a method performed by a base station is provided. The method includes transmitting, to a user equipment (UE), a radio resource control (RRC) message for configuring a transmission of a packet data convergence protocol (PDCP) sequence number (SN) gap report; and receiving, from the UE, a PDCP SN gap report, wherein the PDCP SN gap report includes at least one of a first discarded count (FDC) field and a discard bitmap field.

[0011] In accordance with an aspect of the disclosure, a user equipment (UE) is provided. The UE comprises a transceiver, and a controller coupled with the transceiver, and configured to receive, from a base station, a radio resource control (RRC) message for configuring a transmission of a packet data convergence protocol (PDCP) sequence number (SN) gap report, identify whether to trigger a packet data convergence protocol (PDCP) sequence number (SN) gap report, and in case that the PDCP SN gap report is triggered, transmitting, to the base station, the PDCP SN gap report, wherein the PDCP SN gap report includes at least one of a first discarded count (FDC) field and a discard bitmap field.

[0012] In accordance with an aspect of the disclosure, a base station is provided. The base station comprises a transceiver, and a controller coupled with the transceiver, and configured to transmit, to a user equipment (UE), a radio resource control (RRC) message for configuring a transmission of a packet data convergence protocol (PDCP) sequence number (SN) gap report, and receive, from the UE, a PDCP SN gap report, wherein the PDCP SN gap report includes at least one of a first discarded count (FDC) field and a discard bitmap field.

[0013] Advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. For more enhanced communication system, there is a need for method and apparatus for avoiding a managing packet discard signaling for extended reality (XR) in a communication system.

[0014] This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:

[0015] FIG. 1 is the block diagram of a first electronic device for managing packet discard signalling for XR in a communication system according to embodiments as disclosed herein;

[0016] FIG. 2 is the block diagram of a second electronic device for managing packet discard signalling for XR in a communication system according to embodiments as disclosed herein;

[0017] FIG. 3 is a flowchart that illustrates a method for triggering packet discard signalling for XR in a communication system according to embodiments as disclosed herein;

[0018] FIG. 4 is a flowchart that illustrates a mechanism for generating and transmitting a PDCP SN gap report in response to the triggering of the packet discard signalling for XR in a communication system according to embodiments as disclosed herein.

[0019] FIG. 5 is a flowchart that illustrates a method for transmitting PDCP entity of the first electronic device of setting of the Discard Bitmap field according to embodiments as disclosed herein.

[0020] FIG. 6 is a flowchart that illustrates a method for transmitting PDCP entity of the first electronic device for allocating length of the Discard Bitmap field according to embodiments as disclosed herein.

[0021] FIG. 7 is a flowchart that illustrates a mechanism for setting the FDC field by the transmitting PDCP entity of the first electronic device according to embodiments as disclosed herein.

[0022] FIG. 8 is a flowchart that illustrates a method for handling of the PDCP Control PDU comprising discard information by the receiving PDCP entity of the second electronic device according to embodiments as disclosed herein.

[0023] FIG. 9 is a flowchart that illustrates a method for delivering PDCP SDUs to the upper layers based on the indication of the discarded SDUs in the packet discard signalling according to embodiments as disclosed herein.

[0024] FIG. 10 is a flowchart that illustrates a PDCP SN gap controller mechanism of transmitting packet discard signalling and receiving and handling of packet discard signalling for XR in a communication system according to embodiments as disclosed herein.

[0025] These and other aspects of the example embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating example embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the example embodiments herein without departing from the spirit thereof, and the example embodiments herein include all such modifications.

[0026] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

[0027] For the purposes of interpreting this specification, the definitions (as defined herein) will apply and whenever appropriate the terms used in singular will also include the plural and vice versa. It is to be understood that the terminology used herein is for the purposes of describing particular embodiments only and is not intended to be limiting. The terms "comprising", "having" and "including" are to be construed as open-ended terms unless otherwise noted.

[0028] The words / phrases "exemplary", "example", "illustration", "in an instance", "and the like", "and so on", "etc.", "etcetera", "e.g.," , "i.e.," are merely used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein using the words / phrases "exemplary", "example", "illustration", "in an instance", "and the like", "and so on", "etc.", "etcetera", "e.g.," , "i.e.," is not necessarily to be construed as preferred or advantageous over other embodiments.

[0029] Embodiments herein may be described and illustrated in terms of blocks which carry out a described function or functions.　These blocks, which may be referred to herein as managers, units, modules, hardware components or the like, are physically 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, hardwired circuits and the like, and may optionally be driven by a firmware. The circuits may, for example, be embodied in one or more semiconductor chips, or on substrate supports such as printed circuit boards and the like.　The circuits constituting a block may be implemented by dedicated hardware, or by a processor (e.g., one or more programmed microprocessors and associated circuitry), or by a combination of dedicated hardware to perform some functions of the block and a processor to perform other functions of the block.　Each block of the embodiments may be physically separated into two or more interacting and discrete blocks without departing from the scope of the disclosure.　Likewise, the blocks of the embodiments may be physically combined into more complex blocks without departing from the scope of the disclosure.

[0030] It should be noted that elements in the drawings are illustrated for the purposes of this description and ease of understanding and may not have necessarily been drawn to scale. For example, the flowcharts / sequence diagrams illustrate the method in terms of the steps required for understanding of aspects of the embodiments as disclosed herein. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the present embodiments so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Furthermore, in terms of the system, one or more components / modules which comprise the system may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the present embodiments so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0031] 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. As such, the present disclosure should be construed to extend to any modifications, equivalents, and substitutes in addition to those which are particularly set out in the accompanying drawings and the corresponding description. Usage of words such as first, second, third etc., to describe components / elements / steps is for the purposes of this description and should not be construed as sequential ordering / placement / occurrence unless specified otherwise.

[0032] The XR, which includes Virtual Reality (VR), Augmented Reality (AR), and Mixed Reality (MR), represents a significant advancement in human-computer interaction. This technology is a crucial component of 5G and 5G-Advanced communication systems and is set to revolutionize how individuals engage with digital environments. XR offers immersive experiences that blend real and virtual worlds and is instrumental in the development of digital twins and the meta-universe. These advancements promise to enhance various sectors, including entertainment, education, healthcare, and remote work.

[0033] Despite its transformative potential, the integration of XR services into existing and future wireless networks presents numerous challenges. The 3GPP New Radio (NR) framework, which supports XR, is tasked with accommodating the demanding requirements of these applications, including high data rates, ultra-low latency, and power-efficient connectivity. As XR applications become more prevalent, the pressure on network infrastructure to efficiently manage these requirements intensifies.

[0034] A critical component in the wireless network architecture is the Protocol Data Convergence Protocol (PDCP) layer, which is responsible for various functionalities such as Service Data Unit (SDU) discard, ciphering, integrity protection, header compression, reordering, deciphering, integrity verification, duplicate discarding, and header decompression. These functions are essential for maintaining the security, efficiency, and reliability of data transmission in wireless networks.

[0035] However, the existing mechanisms employed by the PDCP for handling SDUs, particularly the SDU discard process, are not well-suited for the unique demands of XR applications. XR services often involve tightly coupled frame or PDU Set transmissions rather than the typical one-to-one mapping of IP packets to PDCP SDUs. This discrepancy can lead to inefficiencies, especially in scenarios where there is a delay in the receiver's operation to provide timely delivery of the received SDUs.

[0036] This discrepancy can result because of frequent and drastic SDU discards for XR due to the stringent low latency requirements. Particularly, the receiving PDCP entity may incur reordering delays due to gaps caused in the received PDCP SDUs by the discarded SDUs at the transmitting PDCP entity. Invention embodiments target specifying packet discard signaling between the transmitting (Tx) PDCP and receiving (Rx) PDCP entities, including the details on triggering, composing discard information, and the operations for transmitting and receiving this information.

[0037] It is desired to address the above-mentioned disadvantages or other short- comings or at least provide a useful alternative.

[0038] The principal object of the invention herein is to provide a method and a system for managing packet discard signalling for XR in a communication system.

[0039] Another objective of the invention herein is to provide triggers to initiate discard signalling for XR in wireless networks.

[0040] Yet another objective of the invention herein is composing and transmitting a PDCP SN gap report.

[0041] Yet another objective of the invention herein is receiving and handling a PDCP SN gap report and further updating PDCP state variables based on the PDCP SN gap report.

[0042] Yet another objective of the invention herein is managing PDCP reordering and delivery for XR in wireless networks.

[0043] Yet another objective of the invention herein is configuring bearers for PDCP SN gap reporting for XR in wireless networks.

[0044] In an aspect, the objects are achieved by providing a method and system for managing packet discard signalling for XR in a communication system. The method includes a first electronic device receiving a Radio Resource Control (RRC) signalling message from a second electronic device, which includes a PDCP configuration for the radio bearer and specifies discard information for the transmitting PDCP entity. The first electronic device then determines if the triggering criteria for packet discard signalling are met, which includes conditions such as discarded PDCP SDUs, SDUs with a COUNT value larger than that of the discarded SDUs, or discarded SDUs not submitted by Radio Link Control (RLC) to lower layers (such as the RLC layer, the MAC layer, and the PHY layer from the PDCP entity. If the criteria are met, the first electronic device triggers packet discard signalling with discard information to the second electronic device's receiving PDCP entity to generate a PDCP Sequence Number (SN) gap report. If the criteria are not met, no triggering occurs.

[0045] In another aspect, the objects are achieved by providing a system for managing packet discard signalling (i.e., PDCP SN gap reporting) for XR in a communication system. The system includes a first electronic device comprising a transmitting entity and a receiving entity, and a second electronic device also with a transmitting and receiving entity. Each includes a memory, a processor, and a PDCP SN gap controller connected to the memory and processor. The PDCP SN gap controller in the first electronic device determines if triggering criteria are met for generating a PDCP SN gap report wherein PDCP SN gap report triggering criteria comprises at least one of at least one PDCP Service Data Units (SDU) are discarded, at least one stored PDCP SDU is associated with a COUNT value larger than a COUNT value associated with the at least one discarded PDCP SDU, and the at least one discarded PDCP SDU have not been submitted by a Radio Link Control (RLC) to lower layers (such as the MAC layer, and the PHY layer). If the criteria are met, it triggers packet discard signalling with discard information for the second electronic device to generate the PDCP SN gap report. If not met, no packet discard signalling is triggered. The second electronic device's receiving PDCP entity receives the packet discard signalling and checks whether the COUNT value of the discarded SDUs in the discard information is within the reordering window, ignoring or processing the discard information accordingly.

[0046] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein, and the embodiments herein include all such modifications.

[0047] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The term "or" as used herein, refers to a non-exclusive or, unless otherwise indicated. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those skilled in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

[0048] As is existing in the field, embodiments may be described and illustrated in terms of blocks which carry out a described function or functions. These blocks, which may be referred to herein as units or modules or the like, 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, hardwired circuits, or the like, and may optionally be driven by firmware. The circuits may, for example, be embodied in one or more semiconductor chips, or on substrate supports such as printed circuit boards and the like. The circuits constituting a block may be implemented by dedicated hardware, or by a processor (e.g., one or more programmed microprocessors and associated circuitry), or by a combination of dedicated hardware to perform some functions of the block and a processor to perform other functions of the block. Each block of the embodiments may be physically separated into two or more interacting and discrete blocks without departing from the scope of the invention. Likewise, the blocks of the embodiments may be physically combined into more complex blocks without departing from the scope of the invention.

[0049] 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. As such, the present disclosure should be construed to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings. Although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are generally only used to distinguish one element from another.

[0050] In the rapidly evolving landscape of wireless communication, the integration of XR applications poses unique challenges, particularly in terms of ensuring timely data delivery and efficient network resource utilization. XR applications, which encompass augmented reality (AR), virtual reality (VR), and mixed reality (MR), demand high data throughput and low latency to provide seamless user experiences. The SDU discard for XR may be quite frequent and drastic due to low latency requirements. Particularly, receiving PDCP entity may incur reordering delays due to SN gaps caused in the received PDCP SDU by the discarded SDUs at the transmitting PDCP entity. The existing system, therefore, has notable limitations that can hinder the performance of XR applications.

[0051] The current SDU discard procedure involves discard of the PDCP SDU when the associated timer is expired or the successful delivery of a PDCP SDU is confirmed from peer PDCP entity e.g. through a PDCP status report. For XR applications, the existing PDCP SDU discard may not be efficient and effective as the XR applications are more tightly coupled with the frame (e.g. a group of packets, video frame, slice) transmission and not with the IP packet transmission which is typically one-to-one mapped to PDCP SDU. For XR, an enhanced discard mechanism that considers the discarding at the level of PDU Set (e.g. a group of SDUs that belong to same frame or slice) is introduced. However, regardless of whether discard is performed at SDU level or PDU Set level, there are drawbacks associated with the PDCP discard mechanism. When discard is performed, it may result in to SN gap. When the SDUs are received at the receiver entity, the SN gap may cause the reordering timer to run the full course and upon expiry of reordering timer, receiver entity will realize the loss of the SDUs with associated SN. This causes a delay in the receiver operation to provide timely delivery of the received SDUs.

[0052] In the description of the embodiment of the invention, the term COUNT or SN has been used interchangeably. In general, COUNT may comprise Hyper Frame Number (HFN) and SN. This does not limit or restrict the invention embodiments in any way.

[0053] To overcome these limitations, the proposed invention introduces a solution for managing packet discard signaling for extended XR in a communication system. method for managing packet discard signalling for extended reality (XR) in a communication system involves receiving, by a first electronic device (100), a Radio Resource Control (RRC) signalling message containing a PDCP configuration for the radio bearer from a second electronic device (200), where the PDCP configuration includes a discard information required parameter to configure the transmitting PDCP entity (108) of the first device (100) to provide packet discard signalling to a receiving PDCP entity of the second device (200). The first device (100) then determines whether a triggering criterion is met at the transmitting PDCP entity, where the PDCP SN gap report triggering criteria may include the discarding of at least one PDCP Service Data Unit (SDU), a stored PDCP SDU having a COUNT value greater than that of the discarded SDU, or the discarded SDUs not being submitted by the Radio Link Control (RLC) to lower layers. If the criteria are met, the first device (100) triggers packet discard signalling with discard information to the receiving PDCP entity of the second device (200) for generating a PDCP Sequence Number (SN) gap report for the radio bearers; otherwise, the device refrains from triggering the signalling.

[0054] In an embodiment, the first electronic device (100) is a user equipment and the second electronic device (200) is a network apparatus. Further, each has transmitting and receiving entities.

[0055] In an embodiment, the first electronic device (100) is a network apparatus and the second electronic device (200) is a user equipment. Further, each has transmitting and receiving entities.

[0056] In an embodiment, the method includes generating, by the first electronic device (100), the PDCP SN gap report at the transmitting PDCP entity in response to the triggering, wherein the PDCP SN gap report is compiled by setting at least one of a First Discarded COUNT (FDC) field and a Discard Bitmap field; and transmitting, by the first electronic device (100), the PDCP SN gap report from the transmitting PDCP entity to the lower layers of the first electronic device (100) for an Uu interface, wherein Uu interface is the air interface between the first electronic device and the second electronic device.

[0057] In an embodiment, the method includes transmitting the discard information comprises setting, by the first electronic device (100), a PDCP Control PDU type field to a value of 100 to indicate that a PDCP Control PDU comprises the PDCP SN gap report; and transmitting, by the first electronic device (100), the PDCP SN gap report in the PDCP Control PDU.

[0058] In an embodiment, the method includes setting of the Discard Bitmap field comprises determining, by the first electronic device (100) at the transmitting PDCP entity (108), that more than one PDCP SDU are discarded; allocating, by the transmitting PDCP entity of the first electronic device (100) of the Discard Bitmap field, setting, by the transmitting PDCP entity of the first electronic device (100), in the Discard Bitmap field as "0" for all PDCP SDUs that have not been discarded; and setting, by the transmitting PDCP entity of the first electronic device (100), in the Discard Bitmap field as "1" for all PDCP SDUs that have been discarded.

[0059] In an embodiment, the method includes allocating, by the transmitting PDCP entity (108) of the first electronic device (100) the Discard Bitmap field comprises determining, by the first electronic device (100), the Discard Bitmap field for PDCP SDUs, wherein the Discard Bitmap field is octet aligned and is a multiple of 8 bits; establishing by the first electronic device, a maximum size for a PDCP SDU, wherein the maximum size is 9000 bytes, configuring by the first electronic device (100), the Discard Bitmap field to exclude considering a COUNT value of a first discarded PDCP SDU and to include considering the COUNT values from a next PDCP SDU to and including a last discarded PDCP SDU, generating by the first electronic device (100), the PDCP Control PDU comprising the discard information corresponding to discarded PDCP SDUs; and determining, by the first electronic device (100), whether a size of the PDCP Control PDU is equal to or more than 9000 bytes, performing, by the one of: allocating a length of the Discard Bitmap such that the PDCP Control PDU is rounded to 9000 bytes, when the size of the PDCP Control PDU is determined to be equal to or more than 9000 bytes, and rounding the PDCP Control PDU to the next multiple of 8 bits that includes the last discarded PDCP SDU, when the size of the PDCP Control PDU is determined to be less than 9000 bytes.

[0060] In an embodiment, the method includes setting of the FDC field comprises setting, by the transmitting PDCP entity of the first electronic device (100), the FDC field to a smallest COUNT value among COUNT values associated with the discarded PDCP SDUs; determining, by the transmitting PDCP entity of the first electronic device (100), that only a single PDCP SDU is discarded; and omitting, by the transmitting PDCP entity of the first electronic device (100), a Discard Bitmap field in a PDCP Control PDU, to indicate the discard of the single PDCP SDU, wherein a length of the Discard Bitmap field is set to 0.

[0061] In an embodiment, the method includes FDC field is always present irrespective of whether a single PDCP SDU or multiple PDCP SDUs are discarded and wherein the Discard Bitmap field in a PDCP Control PDU is present only when multiple PDCP SDUs are discarded.

[0062] In an embodiment, the method includes discarding, by the first electronic device (100), the at least one PDCP SDU when it is not yet assigned a COUNT value at the transmitting PDCP entity; and excluding, by the first electronic device (100), the at least one discarded PDCP SDU from the discard information carried in the discard signalling.

[0063] In an embodiment, the method includes PDCP SN gap report is comprised in a PDCP Control Protocol Data Unit (PDU), and wherein the PDCP Control PDU comprising the PDCP SN gap report is submitted to only one RLC entity when the PDCP entity is associated with one or more RLC entities.

[0064] In an embodiment, the method includes PDCP Control PDU comprising the PDCP SN gap report is submitted to only one associated RLC entity when the PDCP entity is associated with one or more RLC entities, and wherein the associated RLC entity being either a primary RLC entity or a split secondary RLC entity in a dual connectivity scenario.

[0065] In an embodiment, the method includes processing, by the first electronic device (100) at the transmitting PDCP entity, the PDCP SN gap report as delay-critical PDCP data volume while pursuing a Delay Status Report (DSR).

[0066] In an embodiment, the method includes receiving, by the second electronic device (200) at a receiving PDCP entity, a PDCP Control PDU from a first electronic device (100), wherein the PDCP Control PDU comprises discard information for one or more discarded Service Data Units (SDUs), each SDU associated with a COUNT value; determining, by the second electronic device (200) at the receiving PDCP entity, whether the COUNT value of the discarded SDUs in the discard information is outside a reordering window; ignoring, by the second electronic device (200) at the receiving PDCP entity, the discard information in the PDCP Control PDU for the discarded SDUs having the COUNT value outside the reordering window when the COUNT value of the discarded SDUs is outside the reordering window; and processing, by the second electronic device (200) at the receiving PDCP entity, the discard information in the PDCP Control PDU for other discarded SDUs having COUNT values within the reordering window.

[0067] In an embodiment, the method includes updating, by the second electronic device (200) at the receiving PDCP entity, a receive delivery (RX_DELIV) state variable to a COUNT value of a first PDCP SDU that has not been delivered to upper layers of the second electronic device (200) and is not considered as discarded, wherein the COUNT value is greater than the RX_DELIV value.

[0068] In an embodiment, the method includes considering, by the second electronic device (200) at the receiving PDCP entity, that the COUNT values for the PDCP SDUs indicated as discarded in the PDCP SN gap report are to be assumed as received while delivering all stored PDCP SDUs with consecutively associated COUNT values to upper layers in an ascending order of the associated COUNT values.

[0069] In an embodiment, the method includes the first electronic device (100) is a user equipment and the second electronic (200) device is a network apparatus.

[0070] In an embodiment, the method includes first electronic device (100) is a network apparatus and the second electronic device (200) is a user equipment.

[0071] In an embodiment, the system includes for managing packet discard signalling for extended reality (XR) in a communication system includes a first electronic device (100) with a transmitting entity and a receiving entity, and a second electronic device (200) connected to the first electronic device (100), also comprising a transmitting entity and a receiving entity. The first electronic device (100) consists of a memory (102), a processor (101), and a PDCP SN gap controller (103) connected to both the memory and processor. The SN gap controller (103) determines whether a triggering criterion is met at the transmitting PDCP entity, where the PDCP SN gap report triggering criteria include at least one of: the discarding of at least one PDCP Service Data Unit (SDU), a stored PDCP SDU having a COUNT value greater than the COUNT value of the discarded SDU, or the discarded SDU not being submitted by the Radio Link Control (RLC) to lower layers. The controller then performs one of two actions: either triggering the packet discard signalling, which includes discard information to the receiving PDCP entity of the second electronic device (200) for generating a PDCP Sequence Number (SN) gap report for the radio bearers, when the triggering criteria are met, or determining not to trigger the packet discard signalling when the criteria are not met.

[0072] In an embodiment, the system includes the second electronic device (200) comprises a memory (202), a processor (201), and a PDCP SN gap controller (203) connected to both the memory and processor. The PDCP SN gap controller (203) receives the PDCP Control PDU from the first electronic device (100) at a receiving PDCP entity and determines whether the COUNT value of the discarded SDUs in the discard information is outside a reordering window. If the COUNT value of the discarded SDUs is outside the reordering window, the receiving PDCP entity ignores the discard information for those SDUs. Otherwise, the receiving PDCP entity processes the discard information for the discarded SDUs with COUNT values within the reordering window.

[0073] In an embodiment, system includes the first electronic device (100) is a user equipment and the second electronic (200) device is a network apparatus.

[0074] In an embodiment, system includes the first electronic device (100) is a network apparatus and the second electronic device (200) is a user equipment.

[0075] Referring now to the drawings, and more particularly to FIGS. 1 to 10, there are shown preferred embodiments.

[0076] FIG. 1 is the block diagram of a first electronic device for managing packet discard signalling for XR in a communication system. The first electronic device (100) includes a processor (101), a memory (102), the PDCP SN gap Controller (103).

[0077] Examples of the first electronic device (100) can include, but are not limited to, Consumer Electronics (such as Mobile Phones and Smartphones), Tablets, Wearable Devices, Computing Devices (such as Laptops, Notebooks, Desktops, Workstations, etc.), Television, IoT Devices, Automotive Systems (such as connected cars, Autonomous Vehicles, Vehicle-to-Everything (V2X) communication devices, etc.), Enterprise Devices such as robotics, Specialized Equipment (such as Medical Devices, Public Safety Devices, etc.), Media Devices (such as Gaming Consoles, Streaming Devices, etc.). These devices are equipped with various sensors and interfaces to support XR applications such as accelerometers, gyroscopes, cameras, and microphones, enabling immersive user experiences. The XR applications may include augmented reality (AR), virtual reality (VR), and mixed reality (MR), which require high data rates and low latency to function effectively. Further, the first electronic device (100) may support edge computing capabilities, allowing them to offload computationally intensive tasks to nearby servers, reducing the processing burden on the device itself.

[0078] Examples of the first electronic device includes wireless communication network system including, but are not limited to, Cellular Networks (such as 2G, 3G, 4G, 5G, Beyond 5G (B5G) / 6G, or advanced cellular networks), Local Area Networks (LANs) (such as Wi-Fi, Li-Fi, etc.), Personal Area Networks (PANs) (such as Bluetooth, Zigbee, Z-Wave, etc.), Wide Area Networks (WANs) (such as Satellite Communication Networks, Long Range Wide Area Network, Narrowband IoT, Low-bandwidth communication for IoT, etc.), Metropolitan Area Networks (MANs), Machine-to-Machine (M2M), Ad Hoc and Mesh Networks, Emerging and Advanced Networks.

[0079] The first electronic device (100) includes a protocol stack of mobile communication systems layers like a Packet Data Convergence Protocol (PDCP) entity (104), a Radio Link Control (RLC) entity (105), a Medium Access Control (MAC) entity (106), and a Physical (PHY) entity (107).

[0080] The PDCP entity (104) is responsible for header compression, encryption, and integrity protection of data packets, ensuring secure and data transmission. In an embodiment, the PDCP entity (104) acts as transmitting PDCP entity when the first electronic device (100) acts as a transmitter and performs transmitter related operations. Similarly, the PDCP entity (104) acts as receiving PDCP entity when the first electronic device (100) acts as a receiver and performs receiver related operations. The RLC entity (105) manages the segmentation and reassembly of data packets, as well as error correction through Automatic Repeat reQuest (ARQ) mechanisms, which are used for maintaining data integrity in XR applications. The MAC layer (106) handles the scheduling and prioritization of data packets, coordinating access to the shared wireless medium to optimize network resource utilization. The PHY entity (107) is responsible for the modulation and demodulation of signals, as well as the transmission and reception of data over the air interface, utilizing advanced techniques such as OFDM (Orthogonal Frequency Division Multiplexing) and beamforming to enhance signal quality and coverage.

[0081] The processor (101), is responsible for executing instructions and managing the overall operation of the first electronic device (100), including the enhanced packet discard signaling mechanism. The processor (101), communicates with the memory (102) and the PDCP SN gap Controller (103). The processor (101) is configured to execute instructions stored in the memory (102), (102) and to perform various processes for real-time data processing in XR applications. The processor (101) may include one or a plurality of processors, maybe a general-purpose processor, such as a central processing unit (CPU), an application processor (AP), or the like, a graphics-only processing unit such as a graphics processing unit (GPU), a visual processing unit (VPU), and / or an Artificial intelligence (AI) dedicated processor such as a neural processing unit (NPU).

[0082] The memory (102) stores the operating system, application software, and temporary data used by the processor (101). The memory (102) stores Physical Downlink Control Channel (PDCCH) information, Downlink Control Information (DCI) information, and Physical Downlink Shared Channel (PDSCH) information. The memory (102) stores instructions to be executed by the processor (101). The memory (102), may include non-volatile storage elements. Examples of such non-volatile storage elements may include magnetic hard discs, optical discs, floppy discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories. In addition, the memory (102) may, in some examples, be considered a non-transitory storage medium. The term "non-transitory" may indicate that the storage medium is not embodied in a carrier wave or a propagated signal. However, the term "non-transitory" should not be interpreted that the memory (102), is non-movable. In some examples, the memory (102), can be configured to store larger amounts of information than the memory. In an example, a non-transitory storage medium may store data that can, over time, change (e.g., in Random Access Memory (RAM) or cache).

[0083] The PDCP SN gap Controller (103), is a hardware designed to manage the packet discard signalling for XR in communication system. The PDCP SN gap Controller (103) is physically implemented by analog or digital circuits such as logic gates, integrated circuits, memory circuits, passive electronic components, active electronic components, optical components, hardwired circuits, or the like, and may optionally be driven by firmware. The PDCP SN gap Controller (103) determines whether a triggering criterion is met at the transmitting PDCP entity, where the PDCP SN gap report triggering criteria include at least one of: the discarding of PDCP Service Data Units (SDUs), a stored PDCP SDU having a COUNT value greater than that of a discarded PDCP SDU, or the discarded PDCP SDUs not being submitted by a Radio Link Control (RLC) to lower layers. Based on whether the criteria are met, the system performs one of two actions at the transmitting PDCP entity: either triggering the packet discard signalling, which includes discard information sent to a receiving PDCP entity of the second electronic device (200) for generating a PDCP Sequence Number (SN) gap report for the radio bearers, or determining not to trigger the packet discard signalling when the criteria are not met.

[0084] In an embodiment, the proposed invention enables an efficient approach for packet discard signaling and achieving low-latency operations for XR. Further, the PDCP SN gap Controller (103)'s ability to dynamically adjust the priority of the PDCP SDUs based on real-time conditions is a key feature that enhances the overall performance and efficiency of the UE (100) in various network scenarios.

[0085] The PDCP SN gap Controller (103) determines whether triggering criteria are met at the transmitting PDCP entity. These criteria include conditions like, PDCP SDUs are discarded, at least one stored SDUs is associated with COUNT values larger than the discarded ones, or discarded SDUs have not been submitted by the Radio Link Control (RLC) to lower layers such as the MAC entity (106), and the PHY entity (107). If the PDCP SN gap Controller (103) checks and finds that the criteria are met, the controller triggers packet discard signaling to generate a PDCP SN gap report ans sending to the receiving PDCP entity of the second electronic device. If the criteria are not met, no signaling is triggered. Furthermore, improved synchronization between transmitting and receiving entities is made possible by the ability to generate and sending a PDCP SN gap report.

[0086] In an embodiment the first electronic device (100) includes a transmitting entity and a receiving entity and a second electronic device (200) connected to the first electronic device (100) and comprising a transmitting entity and a receiving entity for managing packet discard signalling for extended reality (XR) in a communication system.

[0087] FIG. 2 is the block diagram of a second electronic device for managing packet discard signalling for XR in a communication system. The second electronic device (200) includes a processor (201), a memory (202), PDCP SN gap Controller (203).

[0088] Examples of the second electronic device (200) can include, but are not limited to, Consumer Electronics (such as Mobile Phones and Smartphones), Tablets, Wearable Devices, Computing Devices (such as Laptops, Notebooks, Desktops, Workstations, etc.), IoT Devices, Automotive Systems (such as connected cars, Autonomous Vehicles, Vehicle-to-Everything (V2X) communication devices, etc.), Enterprise Devices such as robotics, Specialized Equipment (such as Medical Devices, Public Safety Devices, etc.), Media Devices (such as Gaming Consoles, Streaming Devices, etc.). These devices are equipped with various sensors and interfaces to support XR applications such as accelerometers, gyroscopes, cameras, and microphones, enabling immersive user experiences. The XR applications may include augmented reality (AR), virtual reality (VR), and mixed reality (MR), which require high data rates and low latency to function effectively. Further, the second electronic device (200) may support edge computing capabilities, allowing them to offload computationally intensive tasks to nearby servers, reducing the processing burden on the device itself.

[0089] Examples of the second electronic device (200) includes wireless communication network system including, but are not limited to, Cellular Networks (such as 2G, 3G, 4G, 5G, Beyond 5G (B5G) / 6G, or advanced cellular networks), Local Area Networks (LANs) (such as Wi-Fi, Li-Fi, etc.), Personal Area Networks (PANs) (such as Bluetooth, Zigbee, Z-Wave, etc.), Wide Area Networks (WANs) (such as Satellite Communication Networks, Long Range Wide Area Network, Narrowband IoT, Low-bandwidth communication for IoT, etc.), Metropolitan Area Networks (MANs), Machine-to-Machine (M2M), Ad Hoc and Mesh Networks, Emerging and Advanced Networks.

[0090] The second electronic device (200) includes a protocol stack of mobile communication systems layers like a Packet Data Convergence Protocol (PDCP) entity (204), a Radio Link Control (RLC) entity (205), a Medium Access Control (MAC) entity (206), and a Physical (PHY) entity (207).

[0091] The PDCP entity (204) is responsible for header compression, encryption, and integrity protection of data packets, ensuring secure and data transmission. In an embodiment, the PDCP entity (204) acts as transmitting PDCP entity when the first electronic device (200) acts as a transmitter and performs transmitter related operations. Similarly, the PDCP entity (204) acts as receiving PDCP entity when the first electronic device (200) acts as a receiver and performs receiver related operations. The RLC entity (205) manages the segmentation and reassembly of data packets, as well as error correction through Automatic Repeat reQuest (ARQ) mechanisms, which are used for maintaining data integrity in XR applications. The MAC entity (206) handles the scheduling and prioritization of data packets, coordinating access to the shared wireless medium to optimize network resource utilization. The PHY entity (207) is responsible for the modulation and demodulation of signals, as well as the transmission and reception of data over the air interface, utilizing advanced techniques such as OFDM (Orthogonal Frequency Division Multiplexing) and beamforming to enhance signal quality and coverage.

[0092] The processor (201) is responsible for executing instructions and managing the overall operation of the second electronic device (200), including the enhanced packet discard signalling mechanism. The processor (201) communicates with the memory (202) and the PDCP SN gap Controller (203). The processor (201) is configured to execute instructions stored in the memory (202) and to perform various processes for real-time data processing in XR applications. The processor (201) may include one or a plurality of processors, maybe a general-purpose processor such as a central processing unit (CPU), an application processor (AP), or the like, a graphics-only processing unit such as a graphics processing unit (GPU), a visual processing unit (VPU), and / or an Artificial intelligence (AI) dedicated processor such as a neural processing unit (NPU).

[0093] The memory (202) stores the operating system, application software, and temporary data used by the processor (201). The memory (202) stores Physical Downlink Control Channel (PDCCH) information, Downlink Control Information (DCI) information, and Physical Downlink Shared Channel (PDSCH) information. The memory (202) stores instructions to be executed by the processor (201). The memory (202) may include non-volatile storage elements. Examples of such non-volatile storage elements may include magnetic hard disks, optical disks, floppy disks, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories. In addition, the memory (202) may in some examples be considered a non-transitory storage medium. The term non-transitory may indicate that the storage medium is not embodied in a carrier wave or a propagated signal. However, the term non-transitory should not be interpreted that the memory (202) is non-movable. In some examples, the memory (202) can be configured to store larger amounts of information than the memory. In an example, a non-transitory storage medium may store data that can over time change (e.g., in Random Access Memory (RAM) or cache).

[0094] In an embodiment, the proposed invention enables an efficient approach for packet discard signaling and achieving low-latency operations for XR.

[0095] In an embodiment, the PDCP SN gap Controller (103) determines whether triggering criteria are met at the transmitting PDCP entity (108). These criteria include conditions like one or more PDCP SDUs are discarded (e.g., upon discard timer expiry), one or more stored PDCP SDU is associated with a COUNT value larger than a COUNT value associated with the at least one discarded PDCP SDU, and the at least one discarded PDCP SDU have not been submitted by a RLC to lower layers, SDUs with higher COUNT values than the discarded ones, or SDUs not submitted by the Radio Link Control (RLC) to lower layers such as the MAC entity (106), and the PHY entity (107). If the PDCP SN gap Controller (103) checks and finds that the criteria are met, the controller triggers packet discard signaling to the receiving PDCP entity of the second electronic device (200) to generate an SN gap report. If the criteria are not met, no signaling is triggered.

[0096] FIG. 3 is a flowchart (300) that illustrates a method for transmitting and receiving of managing packet discard signaling for XR in a communication system.

[0097] At step 301, the method includes receiving by the first electronic device (100) an RRC signalling message with PDCP configuration, including the discard information required parameter to enable packet discard signalling.

[0098] At step 302, the method includes the first electronic device (100) checks if the triggering criteria for PDCP SN gap report are met.

[0099] At step 303, the method includes checking if the triggering criteria for PDCP SN gap report are met comprises at least one PDCP Service Data Unit (SDU) is discarded.

[0100] At step 304, the method includes checking if the triggering criteria for PDCP SN gap report are met comprises whether the at least one stored PDCP SDU has a COUNT value larger than the COUNT value of the discarded PDCP SDU.

[0101] At step 305, the method includes checking if the triggering criteria for PDCP SN gap report are met comprises whether the discarded PDCP SDU has not been submitted by the Radio Link Control (RLC) to lower layers (such as the MAC entity (106), and the PHY entity (107)).

[0102] At step 306, the method includes if the above triggering criteria are met, first electronic device (100) triggers packet discard signalling with discard information (i.e., PDCP SN gap report) to the second electronic device (200).

[0103] At step 307, the method includes the generation of a PDCP SN gap report for the radio bearer.

[0104] FIG. 4 is a flowchart (400) that illustrates a mechanism for generating and transmitting a PDCP SN gap report in response to the triggering of the packet discard signalling for XR in a communication system.

[0105] At step 401, the method includes generating the PDCP SN gap report at the transmitting PDCP entity in response to the triggering, PDCP SN gap report is compiled by setting at least one of the First Discarded COUNT (FDC) field and the Discard Bitmap field.

[0106] At step 402, the method including composing the discard information (i.e. PDCP SN gap report) within the PDCP Control PDU.

[0107] At step 403, the method includes setting that the PDCP Control PDU type field to a value of "100", indicating that the PDCP Control PDU contains discard information.

[0108] At step 404, the method includes submitting the PDCP SN gap report from the transmitting PDCP entity to the lower layers of the UE (such as the RLC entity (104), the MAC entity (106), and the PHY entity (107)) and transmit over the Uu interface wherein Uu interface is the air interface between the first electronic device and the second electronic device (200).

[0109] In an embodiment, the transmitting PDCP entity determines at least one gap in the sequence number of the PDCP SDU(s) due to PDCP discard operation and triggers a discard signaling comprising the discard information to be sent to the receiving PDCP entity.

[0110] In an embodiment, the discard signaling comprising the discard information is carried in a PDCP Control PDU. The PDCP Control PDU comprising discard information may be termed as PDCP Discard Information and is identified by a field PDU type included in the PDCP Control PDU carrying a specific value (for example, the 3-bit PDU type field may be set to "100" to indicate that the PDCP Control PDU is PDCP Discard Information).

[0111] In an embodiment, the discard signalling comprising of the discard information is carried in at least one field in the header of the PDCP Data PDU. The at least one field in the header may comprise of the number of consecutive PDCP SDUs that are discarded and having SN earlier than the SN of the PDCP SDU that carries the field in the header of the PDCP Data PDU and the first discarded SDU SN. In an embodiment, the PDCP Data PDU (or corresponding SDU) that carries the at least one field in the header may be discarded, then the next un-discarded PDCP data PDU may carry the at least one field in the header that comprises the discard information for the discarded SDU. In another embodiment, the PDCP Data PDU may not comprise of data (i.e. application payload) when it is carrying the discard information in the header and when data to carry is not available i.e. header only PDCP data PDU is constructed in order to carry the discard signalling. The header-only PDCP data PDU is assigned a COUNT value (or SN) of the next PDCP SDU to be transmitted COUNT (i.e. TX_NEXT).

[0112] In an embodiment, the discard signaling comprising the discard information includes at least one discarded SDU sequence number.

[0113] In an embodiment, the discard signaling comprising the discard information includes at least one set of first discarded SDU COUNT or sequence number (e.g., termed as First Discarded COUNT FDC) and a range of contiguous PDCP SDU(s) (i.e., sequentially ordered PDCP SDU(s)) that are discarded. For example, in a set, the range may be a field or a value or a number that indicates the number of sequentially ordered (or contiguous) SDUs from the first discarded SDU SN that are discarded. The range may or may not include the first discarded SDU. In an alternative embodiment, the range in a set may correspond to the number of the SDUs in the PDU Set that are discarded. The length of the FDC field can be 32 bits.

[0114] FIG. 5 is a flowchart (500) that illustrates a method for transmitting PDCP entity of the first electronic device (100) of setting of the Discard Bitmap field.

[0115] At step 501, the method includes transmitting PDCP entity of the first electronic device determines that more than one PDCP SDU have been discarded.

[0116] At step 502, the method includes transmitting PDCP entity of the first electronic device allocates the length of the Discard Bitmap field.

[0117] At step 503, the method includes transmitting PDCP entity of the first electronic device sets (bits) in the Discard Bitmap field as "0" for all PDCP SDUs that have not been discarded.

[0118] At step 504, the method includes transmitting PDCP entity of the first electronic device (100a) sets (bits) in the Discard Bitmap field as "1" for all PDCP SDUs that have been discarded.

[0119] In an embodiment, when only one SDU is discarded, it is indicated by the FDC field and the range field may be omitted in the PDCP Control PDU. That is, the length of the bitmap field can be 0.

[0120] In an embodiment, when only one contiguous SDU is discarded, it is indicated by the FDC field and the bitmap field may be omitted in the corresponding set of contiguous discard information in the PDCP Control PDU.

[0121] In an embodiment, the transmitting PDCP entity compiles and sends each set of discard information for contiguous discarded SDUs (e.g., consisting of FDC field and / or range field) in a separate PDCP Control PDU to the receiving PDCP entity. That is, multiple PDCP Control PDUs may be transmitted.

[0122] In an embodiment, the transmitting PDCP entity compiles and sends each set of discard information for contiguous discarded SDUs (e.g., consisting of FDC field and / or range field) in a separate PDCP Control PDU to the receiving PDCP entity. That is, multiple PDCP Control PDUs may be transmitted.

[0123] In an embodiment, the at least one set of discard information in the discard signaling (e.g., PDCP Control PDU) may pertain to the discarded SDUs due to the discardTimer expiry and / or due to the discardTimerLowImportance expiry.

[0124] In an embodiment, the two or more sets of discard information included in the discard signaling (e.g., PDCP Control PDU) may be non-contiguous to each other.

[0125] FIG. 6 is a flowchart (600) that illustrates a method for transmitting PDCP entity of the first electronic device for allocating length of the Discard Bitmap field.

[0126] At step 601, the method includes determining the Discard Bitmap field for PDCP SDUs, Discard Bitmap field is octet-aligned and a multiple of 8 bits.

[0127] At step 602, the method includes establishing a maximum size for a PDCP SDU (9000 bytes).

[0128] At step 603, the method includes configuring the Discard Bitmap to exclude considering the COUNT value of the first discarded PDCP SDU, and to include considering COUNT values from the next PDCP SDU up to and including the last discarded PDCP SDU.

[0129] At step 604, the method includes generating the PDCP Control PDU with discard information corresponding to the discarded PDCP SDUs and not discarded PDCP SDUs.

[0130] At step 605, the method includes determining if the size of the PDCP Control PDU is equal to or greater than 9000 bytes.

[0131] At step 606, the method includes if size is ≥ 9000 bytes it will allocate the length of the discard bitmap such that to round the PDCP Control PDU to 9000 bytes, if size is < 9000 bytes, it will round the PDCP Control PDU to the next multiple of 8 bits that includes the last discarded PDCP SDU.

[0132] In an embodiment, the discard signaling comprising the discard information (e.g., PDCP control PDU) includes at least one of the first discarded SDU COUNT or sequence number (e.g., termed as First Discarded COUNT FDC) and a bitmap of contiguous PDCP SDU(s) (i.e., sequentially ordered PDCP SDU(s)) wherein the bitmap indicates either the PDCP SDU is discarded (e.g., corresponding ordered bit in the bitmap is set to 1) or the PDCP SDU is not discarded (e.g., corresponding ordered bit in the bitmap is set to 0). For example, the first bit in the bitmap may refer to the SDU which has the next sequence number to the first discarded SDU sequence number included in the discard information. Further, the bit position in the bitmap may represent PDCP SDU with COUNT FDC + bit position) modulo 232.

[0133] In an embodiment, the bitmap is octet aligned (multiple of 8 bits) and the last bit in the bitmap may not correspond to the last discarded SDU sequence number. In another embodiment, the bits in the bitmap after the last bit which is set to 1 (i.e., SDU SN is discarded) may be interpreted by the receiver as do not care, i.e., the receiver may not determine any discard status for the SDUs with corresponding SNs. The length of the FDC field can be 32 bits.

[0134] In an embodiment, the bitmap field in the PDCP Control PDU comprising discard information is allocated a length in bits equal to the number of COUNTs from and not including the first discarded PDCP SDU up to and including the last discarded PDCP SDU rounded up to the next multiple of 8 or up to and including a PDCP SDU for which the resulting PDCP Control PDU size is equal to 9000 bytes, whichever comes first.

[0135] FIG. 7 is a flowchart (700) illustrating a mechanism for setting the FDC field by the transmitting PDCP entity of the first electronic device (100).

[0136] At step 701, the method includes transmitting PDCP entity of the first electronic device sets the FDC field to the smallest COUNT value among the COUNT values associated with discarded PDCP SDUs.

[0137] At step 702, the method includes transmitting PDCP entity of the first electronic device determines that only a single PDCP SDU is discarded.

[0138] At step 703, the method includes omitting the Discard Bitmap field in the PDCP Control PDU to indicate the discard of the single PDCP SDU, i.e., length of the bitmap field is 0.

[0139] At step 704, the method includes FDC field is always present in the PDCP Control PDU, regardless of whether a single PDCP SDU or multiple PDCP SDUs are discarded.

[0140] At step 705, the method includes the Discard Bitmap field is present in the PDCP Control PDU only when multiple PDCP SDUs are discarded.

[0141] In an embodiment, the SDU discard procedure involves the discard of the PDCP SDU when the associated timer has expired or the successful delivery of a PDCP SDU is confirmed from the peer PDCP entity, e.g., through a PDCP status report. For XR applications, the existing PDCP SDU discard may not be efficient and effective as the XR applications are more tightly coupled with the frame (e.g., a group of packets, video frame slice) transmission and not with the IP packet transmission, which is typically one-to-one mapped to PDCP SDU. For XR, an enhanced discard mechanism that considers the discarding at the level of PDU Set (e.g., a group of SDUs that belong to the same frame or slice) is introduced. However, regardless of whether discard is performed at the SDU level or PDU Set level, there are drawbacks associated with the PDCP discard mechanism. When discard is performed, it may result in an SN gap. When the SDUs are received at the receiver entity, the SN gap may cause the reordering timer to run the full course, and upon expiry of the reordering timer, the receiver entity will realize the loss of the SDUs with the associated SN. This causes a delay in the receiver operation to provide timely delivery of the received SDUs.

[0142] In an embodiment, the bitmap field in the PDCP Control PDU comprising discard information is allocated a length in bits equal to the number of COUNTs from and not including the first discarded PDCP SDU up to and including the PDCP SDU with COUNT as TX_NEXT minus 1 (i.e., COUNT preceding TX_NEXT), rounded up to the next multiple of 8 or up to and including a PDCP SDU for which the resulting PDCP Control PDU size is equal to 9000 bytes, whichever comes first.

[0143] In an embodiment, when only one SDU is discarded, it is indicated by the FDC field, and the bitmap field may be omitted in the PDCP Control PDU. That is, the length of the bitmap field can be 0.

[0144] In an embodiment, First Discarded COUNT (FDC) may also be termed as First Missing Count (FMC), and discarded SDU(s) may also be termed as missing SDU(s).

[0145] In an embodiment, subsequently received SDUs of a PDU Set from the upper layers after the associated discard timer and / or discard timer low importance has already expired, are not assigned COUNT (or SN) and further, these SDUs of the PDU Set are discarded and are not accounted in the discard information carried in the discard signaling. The SDUs of the PDU Set other than the subsequently received SDUs of the PDU Set are accounted in the discard information carried in the discard signaling.

[0146] In an embodiment, PDCP SN gap is determined and discard signaling is triggered by the transmitting PDCP entity when at least one SDU / PDU is discarded (e.g., when PDU Set discard (pdu-SetDiscard) is not configured) or at least one PDU Set is discarded (e.g., when PDU Set discard (pdu-SetDiscard) is configured) or at least one SDU / PDU of the PDU Set is discarded (e.g., when PDU Set discard (pdu-SetDiscard) is configured) and at least one discarded SDU / PDU or at least one SDU / PDU of the discarded PDU Set was not yet submitted to associated RLC entity or entities. The at least one discarded SDU or at least one SDU of the discarded PDU Set may have been assigned COUNT by the transmitting PDCP entity.

[0147] In an embodiment, PDCP SN gap is determined and discard signaling is triggered by the transmitting PDCP entity when at least one SDU / PDU is discarded (e.g., when PDU Set discard (pdu-SetDiscard) is not configured) or at least one PDU Set is discarded (e.g., when PDU Set discard (pdu-SetDiscard) is configured) or at least one SDU / PDU of the PDU Set is discarded (e.g., when PDU Set discard (pdu-SetDiscard) is configured) and at least one discarded SDU / PDU or at least one SDU / PDU of the PDU Set if submitted to associated RLC entity or entities is not transmitted (or not submitted to lower layers such as the MAC entity (106), and the PHY entity (107)) by at least one associated RLC entity. The transmission consideration by at least one associated RLC entity may be for complete SDU and / or a segment of the SDU.

[0148] In an embodiment, at least one of the associated RLC entities conveys to the transmitting PDCP entity when discard indication is received at the RLC entity and the SDU (PDCP PDU) or at least one segment of the SDU (PDCP PDU) is already transmitted (or submitted to lower layers). Accordingly, PDCP entity determines not to trigger discard signaling when at least one of the associated RLC entities conveys to the transmitting PDCP entity that the SDU or at least one segment of the SDU is already transmitted. PDCP entity determines to trigger discard signaling when none of the associated RLC entities conveys to the transmitting PDCP entity that the SDU or at least one segment of the SDU is already transmitted.

[0149] In an embodiment, subsequently received SDUs of a PDU Set from the upper layers after the associated discardTimer and / or discardTimerLowImportance has already expired are not assigned COUNT (or SN) and further these SDUs of the PDU Set are discarded and are not accounted in the discard information carried in the discard signaling. The SDUs of the PDU Set other than the subsequently received SDUs of the PDU Set are accounted in the discard information carried in the discard signaling.

[0150] In an embodiment, when a received SDU is not yet assigned COUNT or SN at the PDCP layer and the SDU is discarded, the SDU is not accounted in the discard information carried in the discard signaling.

[0151] In an embodiment, when a received SDU is assigned COUNT or SN at the PDCP layer and the SDU is discarded and the SDU was not yet submitted to RLC layer, the PDCP may reassign the same COUNT or SN to a new or subsequent SDU. In this case, the discarded SDU is not accounted in the discard information carried in the discard signaling.

[0152] In an embodiment, when an SDU received from the upper layer is assigned COUNT or SN at the PDCP layer and the SDU is discarded and if the SDU was submitted to RLC layer and if neither SDU nor a segment thereof was submitted by RLC to lower layers (such as the MAC entity (106), and the PHY entity (107)), the PDCP may reassign the same COUNT or SN to a new or subsequent SDU. In this case, the discarded SDU is not accounted in the discard information carried in the discard signaling.

[0153] In an embodiment, the PDCP Control PDU comprising of the discard signaling is submitted to only the primary RLC entity when PDCP entity is associated with one or more RLC entities.

[0154] In an embodiment, the PDCP Control PDU comprising of the discard signaling is submitted to only one associated RLC entity when the PDCP entity is associated with one or more RLC entities. The associated RLC entity may be one of the primary RLC entity and split secondary RLC entity (e.g., in dual connectivity).

[0155] In an embodiment, the PDCP Control PDU comprising of the discard signaling is submitted to more than one associated RLC entity when the PDCP entity is associated with one or more RLC entities. The associated RLC entity may be one of the primary RLC entity and split secondary RLC entity (e.g., in dual connectivity).

[0156] In an embodiment, the PDCP Control PDU comprising of the discard signaling is submitted to only either the primary RLC entity or split secondary RLC entity when the PDCP entity is associated with one or more RLC entities. The determination of the RLC entity is based on at least one of whether the associated MAC entity is not experiencing congestion (i.e., PDU Set Importance (PSI) based SDU discard is deactivated) or associated MAC entity for which Cell-DRX is not in non-Active Period or MAC entity which is not in UE DRX non-Active time or associated MAC entity has uplink grant available or the related link is not experiencing comparatively weaker channel conditions.

[0157] In an embodiment, UE indicates its capability to support PDCP discard signaling in a UE capability message and / or through an indication in the UE Assistance Information (UAI) message to the network.

[0158] In an embodiment, UE receives the configuration for the PDCP discard signaling from the network in an RRC signaling message, e.g., RRC reconfiguration message. The configuration may comprise at least one parameter that may include at least one of setup, release, modification, enabling, disabling, prohibit timer, triggers, and triggering conditions for the discard signaling. For example, the configuration parameter may include a parameter discardInformationRequired to configure or indicate the transmitting PDCP entity to provide the discard signaling to the receiving PDCP entity. The configuration may be configured per radio bearer and may be included in the pdcp-Config for the radio bearer configuration in the RRC reconfiguration. Upon being configured with discard signaling functionality in a configuration or reconfiguration by the upper layer that is not used to release or disable the configuration), the PDCP entity (104) applies the discard signaling triggers and initiates the discard signaling on meeting at least one triggering condition.

[0159] In an embodiment, a triggering condition comprising a number of gaps in the sequence number may be considered explicitly by configuring such a number (e.g., in an RRC configuration or reconfiguration) or implicitly by handling the transmitting entity implementation.

[0160] In an embodiment, when a data radio bearer is configured by upper layers to send a PDCP discard information (e.g. discardInformationRequired is configured for the data radio bearer), the transmitting PDCP entity may trigger a PDCP discard signaling to send discard information when at least one of the conditions is met:

[0161] a) Upper layer requests a PDCP entity re-establishment;

[0162] b) Upper layers requests a PDCP data recovery;

[0163] c) Upper layers requests a uplink data switching; and

[0164] d) Upper layer reconfigures the PDCP entity to release DAPS and daps-SourceRelease is configured.

[0165] In an embodiment, an example specification for the transmit operation of the discard signaling is provided as follows:

[0166] Example 1:

[0167] For DRBs configured by upper layers to send a PDCP discard information (discardInformationRequired is configured), the transmitting PDCP entity shall determine a PDCP SN gap and trigger a PDCP discard signaling to send discard information when:

[0168] ▶ a SDU (including SDU belonging to PDU Set) which has an assigned COUNT value is discarded; and

[0169] ▶ SDU was not yet submitted to RLC or if submitted to RLC, neither the SDU nor a segment thereof had been submitted by RLC to the lower layers.

[0170] In an embodiment, an example specification for the transmit operation of the discard signaling is provided as follows:

[0171] Example 2:

[0172] If a PDCP discard signalling is triggered, the transmitting PDCP entity shall:

[0173] ▶ compile a PDCP discard information as indicated below by:

[0174] ● setting the First Discarded COUNT (FDC) field to COUNT of the first PDCP SDU that is discarded;

[0175] ● if FDC < TX_NEXT:

[0176] - allocating a Bitmap field of length in bits equal to the number of COUNTs from and not including the first discarded PDCP SDU up to and including the last discarded PDCP SDU, rounded up to the next multiple of 8, or up to and including a PDCP SDU for which the resulting PDCP Control PDU size is equal to 9000 bytes, whichever comes first;

[0177] - setting in the bitmap field as '0' for all PDCP SDUs that have not been discarded;

[0178] - setting in the bitmap field as '1' for all PDCP SDUs that have been discarded;

[0179] - submit the "PDCP discard information" (i.e. PDCP Control PDU comprising discard information) to lower layers as the first PDCP PDU for transmission via the transmitting PDCP entity as specified in clause 5.2.1 (in TS 38.323) for Uu interface and in clause 5.2.3 (TS 38.323) for PC5 interface.

[0180] In an embodiment, an example specification for the transmit operation of the discard signaling is provided as follows:

[0181] Example 3:

[0182] If a PDCP discard signalling is triggered, the transmitting PDCP entity shall:

[0183] ▶ compile a PDCP discard information as indicated below by:

[0184] ○ for each set of contiguously discarded PDCP SDUs

[0185] ● setting the First Discarded COUNT (FDC) field to COUNT of the first PDCP SDU that is discarded;

[0186] ● if FDC < TX_NEXT:

[0187] -setting a range field to the number of COUNTs from and not including the first discarded PDCP SDU up to and including the last contiguous discarded PDCP SDU, rounded up to and including a PDCP SDU for which the resulting PDCP Control PDU size is not more than 9000 bytes;

[0188] -submit the "PDCP discard information" (i.e. PDCP Control PDU comprising discard information) to lower layers as the first PDCP PDU for transmission via the transmitting PDCP entity as specified in clause 5.2.1 (in TS 38.323) for Uu interface and in clause 5.2.3 (in TS 38.323) for PC5 interface.

[0189] In an embodiment, the transmitting PDCP entity may not repeat previously transmitted discard information partially or completely in subsequently transmitted discard information. That is, discard information of a specific SDU can be transmitted only once. One example is when the discard information is composed based on the discardTimer and / or discardTimerLowImportance expiry, and only corresponding discarded SDU(s) information is compiled and sent in the PDCP Control PDU.

[0190] In an embodiment, the transmitting PDCP entity may repeat previously transmitted discard information partially or completely in subsequently transmitted discard information. That is, discard information of a specific SDU can be transmitted more than once. One example is when the discard information is composed to contain the consecutive SDUs discard or no discard status. Consider firstly a discard information is compiled and sent in a PDCP Control PDU when an SDU (having higher COUNT value) with discardTimerLowImportance is expired, and secondly, later discard information is compiled and sent in a PDCP Control PDU when an SDU (having lower COUNT value) with discardTimer is expired. In such a case, the second PDCP Control PDU may possibly comprise the discard information for both the SDU with lower COUNT value and the SDU with higher COUNT value. Another example is when an SDU which was previously addressed in discard information in the discard signaling as not discarded is now discarded and is addressed again in the discard information in new discard signaling as discarded.

[0191] In an embodiment, the transmitting PDCP entity performs discard information signaling in at least one of the congestion scenario (e.g., when PSI based SDU discard is activated) and non-congestion scenario (e.g., when PSI based SDU discard is deactivated). This may be configured in the RRC signaling or specified in the specification or left to implementation for the discard information managing approach.

[0192] In an embodiment, the transmitting PDCP entity performs discard information signaling for at least one of SDU discard based on discardTimer and SDU discard based on discardTimerLowImportance. This may be configured in the RRC signaling or specified in the specification or left to implementation for the discard information managing approach.

[0193] In an embodiment, a prohibit timer for discard signalling (e.g. termed as t-discardInfoProhibit) is configured or specified that determines that transmitting PDCP entity would not transmit discard signalling frequently. The prohibit timer for discard signalling is configured per radio bearer and when configured, the prohibit timer started when the discard signalling is transmitted. When prohibit timer is running, a triggered discard signalling is not allowed to be transmitted. Upon expiry of prohibit timer or when prohibit timer is not running, a triggered discard signalling is allowed to be transmitted.

[0194] In an embodiment, discard signaling (e.g., PDCP Control PDU comprising the discard information i.e. PDCP SN gap report) is considered as delay-critical PDCP data volume while pursuing Delay Status Report (DSR).

[0195] In an embodiment, as the DSR is triggered when discardTimer (and / or discardTimerLowImportance) expires within the configured threshold time, discard signaling (e.g., PDCP Control PDU comprising the discard information) is not yet available. It is possible the transmitting entity may have uplink resources to send discard signaling. To address this, when discard signaling (e.g., PDCP Control PDU comprising the discard information), a Buffer Status Report (BSR) and / or a Scheduling Request (SR) (e.g., SR for discard signaling) is triggered. In an embodiment, SR for discard signaling may have dedicated SR configuration, or it may share the SR configuration that is used for BSR.

[0196] In an embodiment, the receiving PDCP entity receives non-contiguous discarded PDCP SDUs SN in the discard signaling (e.g., different set of first discarded SDU sequence number and a range of contiguous PDCP SDU(s) (i.e., sequentially ordered PDCP SDU(s)) that are discarded in a PDCP Control PDU or first discarded SDU sequence number and a bitmap for discard information in a PDCP Control PDU).

[0197] FIG. 8 is a flowchart (800) illustrating a method for handling of the PDCP Control PDU comprising discard information by the receiving PDCP entity of the second electronic device.

[0198] At step 801, the method includes receiving PDCP entity of the second electronic device receives a PDCP Control PDU from the first electronic device, PDCP Control PDU contains discard information for one or more discarded SDUs, each associated with a COUNT value.

[0199] At step 802, the method includes determines whether the COUNT value of the one or more discarded SDUs in the discard information is outside the reordering window.

[0200] At step 803, the method includes if the COUNT value of the one or more discarded SDUs is outside the reordering window, the receiving PDCP entity ignores the discard information for those discarded SDUs.

[0201] At step 804, the method includes if the COUNT value of the one or more discarded SDUs is within the reordering window, the receiving PDCP entity processes the discard information for those SDUs.

[0202] In an embodiment, if at least one COUNT value of the discarded SDU in the discard information is outside the reordering window, the receiving PDCP entity ignores the entire discard information included in the PDCP Control PDU.

[0203] In an embodiment, if at least one COUNT value of the discarded SDU in the discard information is outside the reordering window, the receiving PDCP entity ignores only the discard information in the PDCP Control PDU for the corresponding discarded SDU(s) and processes the discard information in the PDCP Control PDU for other discarded SDUs which are within the reordering window.

[0204] FIG. 9 is a flowchart (900) that illustrates as a method for delivering PDCP SDUs to the upper layers based on the indication of the discarded SDUs in the packet discard signalling.

[0205] At step 901, the method includes Receiving PDCP entity of the second electronic device updates the RX_DELIV value to the COUNT value of the first PDCP SDU that has not been delivered to upper layers and is not considered discarded, when the COUNT value is greater than the current RX_DELIV value. At step 902, the method includes considering the COUNT values for the PDCP SDUs indicated as discarded in the PDCP SN gap report are to be assumed as received. At step 903, the method includes delivering all stored PDCP SDUs with consecutively associated COUNT values to the upper layers in ascending order of the COUNT values.

[0206] In an embodiment, the receiving PDCP entity updates the state variable RX_DELIV to the COUNT of the first SDU which is not yet delivered to upper layers such that COUNT >= RX_DELIV and which is either not included in the PDCP control PDU or not indicated as discarded in the PDCP control PDU.

[0207] In an embodiment, the receiving PDCP entity updates the state variable RX_NEXT to the COUNT of the first SDU which is not yet received such that COUNT >= RX_NEXT and which is either not included in the PDCP control PDU or not indicated as discarded in the PDCP control PDU.

[0208] In an embodiment, the receiving PDCP entity records or marks (or performs bookkeeping) for the COUNT of the PDCP SDUs which are indicated as discarded in the PDCP Control PDU such that COUNT > (updated) RX_DELIV and / or COUNT > (updated) RX_NEXT. Further, the receiver entity skips expecting to receive these PDCP SDUs from the transmitting entity or assumes as if these SDUs are received. Accordingly, the receiving PDCP entity updates the state variables, for example, for COUNT of each of the PDCP SDUs recorded or marked (or book-kept) as mentioned earlier. When RX_DELIV becomes equal to COUNT (i.e., RX_DELIV=COUNT), update RX_DELIV to COUNT+1, and when RX_NEXT becomes equal to COUNT (i.e., RX_NEXT=COUNT), update RX_NEXT to COUNT+1.

[0209] In an example, the PDCP control PDU may have one or more sets of discard information, each set of which can be a contiguous discarded SDUs SN range / bitmap (e.g., SN 5, 6, 7 discarded due to discard timer expiry and SN 11, 12 discarded due to discard timer low importance expiry). The receiving PDCP entity may avail advantage from discard signaling when these sets of discard information are not contiguous (i.e., SN 5, 6, 7, 11, and 12). That is, the receiving PDCP entity performs bookkeeping to record or mark non-contiguous discarded SDU SNs (e.g., SN 11 and 12). This may be achieved by just PDCP state variables update.

[0210] In an embodiment, when a PDCP SDU with COUNT is already received by the receiving PDCP entity and it is indicated as discarded in the PDCP Control PDU, the receiving PDCP entity may process (e.g., perform integrity verification, deciphering, header compression) the PDCP SDU and / or deliver it to the upper layer.

[0211] In an embodiment, when a PDCP SDU with COUNT is already received by the receiving PDCP entity and it is indicated as discarded in the PDCP Control PDU, the receiving PDCP entity may not process (e.g., perform integrity verification, deciphering, header compression) the PDCP SDU and / or may not deliver it to the upper layer.

[0212] FIG 10 is a flowchart (1000) illustrating a PDCP SN gap controller mechanism of transmitting packet discard signalling and receiving and handling of packet discard signalling for XR in a communication system.

[0213] At step 1001, the method includes SN Gap controller (103) of the first electronic device (100) evaluates if the triggering criteria (based on discarded PDCP SDUs or COUNT values or submission to lower layer from RLC) are met at the transmitting PDCP entity.

[0214] At step 1002, the method includes If the triggering criteria are met, the first electronic device triggers packet discard signalling and sends discard information (PDCP SN gap report) to the second device's receiving PDCP entity.

[0215] At step 1003, the method includes if the criteria are not met, no packet discard signalling is triggered by the first device (100).

[0216] At step 1004, the method includes the second electronic device (200) checks if the COUNT value of the one or more discarded SDUs is outside the reordering window.

[0217] At step 1005, the method includes if the COUNT value is outside the reordering window, the first device at the receiving PDCP ignores the discard information for those SDUs.

[0218] At step 1006, the method includes if the COUNT value is within the reordering window, the first device processes the discard information for the relevant SDUs.

[0219] In an embodiment, an example for procedure for managing received PDCP discard information at the receiving PDCP entity for XR radio bearer is described as below:

[0220] Example 4:

[0221] For a DRB, when a PDCP Control PDU comprising the PDCP discard information is received, the receiving PDCP entity shall:

[0222] - if at least one COUNT value of the discarded SDU in the discard information is outside the reordering window:

[0223] - ignores the Discard information in the PDCP Control PDU for the corresponding discarded SDU(s);

[0224] - if RX_NEXT <= COUNT value of the last discarded SDU in the discard information:

[0225] - update RX_NEXT to the COUNT of the first SDU which is not yet received such that COUNT >= RX_NEXT and which is either not included in the PDCP control PDU or not indicated as discarded in the PDCP control PDU

[0226] - if RX_DELIV <= COUNT value of the last discarded SDU in the discard information:

[0227] - update RX_DELIV to the COUNT of the first SDU which is not yet delivered to upper layer such that COUNT >= RX_DELIV and which is either not included in the PDCP control PDU or not indicated as discarded in the PDCP control PDU

[0228] - if (updated) RX_DELIV <= COUNT value of the last discarded SDU in the discard information:

[0229] - record the COUNT for the of the PDCP SDUs which are indicated as discarded in the PDCP Control PDU such that COUNT > (updated) RX_DELIV (receiving PDCP entity do not expect these PDCP SDUs to be received);

[0230] - deliver all stored PDCP SDU(s) with consecutively associated COUNT value(s) such that COUNT < (updated) RX_DELIV, while excluding (i.e. ignoring for consecutively associated COUNT consideration) the recorded COUNT values(s) for the PDCP SDUs which are indicated as discarded in the PDCP Control PDU, to upper layers in ascending order of the associated COUNT value (if any) after performing header decompression;

[0231] - if t-Reordering is running, and if RX_DELIV >= RX_REORD:

[0232] - stop and reset t-Reordering.

[0233] - if t-Reordering is not running (includes the case when t-Reordering is stopped due to actions above), and RX_DELIV < RX_NEXT:

[0234] - update RX_REORD to RX_NEXT;

[0235] - start t-Reordering.

[0236] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and / or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Claims

1.A method performed by a user equipment (UE) in a wireless communication system, the method comprising:receiving, from a base station, a radio resource control (RRC) message for configuring a transmission of a packet data convergence protocol (PDCP) sequence number (SN) gap report;identifying whether to trigger a packet data convergence protocol (PDCP) sequence number (SN) gap report; andin case that the PDCP SN gap report is triggered, transmitting, to the base station, the PDCP SN gap report,wherein the PDCP SN gap report includes at least one of a first discarded count (FDC) field and a discard bitmap field.2.The method of claim 1, wherein the PDCP SN gap report is triggered:in case that at least one PDCP service data unit (SDU) is discarded, orin case that there is at least one stored PDCP SDU which is associated with a count value larger than a count value associated to a discarded PDCP SDU, orin case that the at least one discarded PDCP SDU has not been submitted by a radio link control (RLC) to lower layers.3.The method of claim 1, further comprising:setting the first discarded count (FDC) field in the PDCP SN gap report,wherein the FDC field indicates the smallest count value among count values associated with the at least one discarded PDCP SDU.4.The method of claim 1, further comprising:allocating the discard bitmap field of length in bits equal to the number of count values from and not including a first discarded PDCP SDU up to and including the last discarded PDCP SDU.5.The method of claim 1,wherein the PDCP SN gap report is transmitted via a PDCP control protocol data unit (PDU).6.A method performed by a base station in a wireless communication system, the method comprising:transmitting, to a user equipment (UE), a radio resource control (RRC) message for configuring a transmission of a packet data convergence protocol (PDCP) sequence number (SN) gap report; andreceiving, from the UE, a PDCP SN gap report,wherein the PDCP SN gap report includes at least one of a first discarded count (FDC) field and a discard bitmap field.7.The method of claim 6,wherein the FDC field indicates the smallest count value among count values associated with the at least one discarded PDCP SDU, andwherein the discard bitmap field of length is allocated in bits equal to the number of count values from and not including a first discarded PDCP SDU up to and including the last discarded PDCP SDU.8.The method of claim 6,wherein the PDCP SN gap report is received via a PDCP control protocol data unit (PDU).9.A user equipment (UE) in a wireless communication system, the UE comprising:a transceiver; anda controller coupled with the transceiver, and configured to:receive, from a base station, a radio resource control (RRC) message for configuring a transmission of a packet data convergence protocol (PDCP) sequence number (SN) gap report,identify whether to trigger a packet data convergence protocol (PDCP) sequence number (SN) gap report, andin case that the PDCP SN gap report is triggered, transmitting, to the base station, the PDCP SN gap report,wherein the PDCP SN gap report includes at least one of a first discarded count (FDC) field and a discard bitmap field.10.The UE of claim 9, wherein the PDCP SN gap report is triggered:in case that at least one PDCP service data unit (SDU) is discarded, orin case that there is at least one stored PDCP SDU which is associated with a count value larger than a count value associated to a discarded PDCP SDU, orin case that the at least one discarded PDCP SDU has not been submitted by a radio link control (RLC) to lower layers.11.The UE of claim 9, wherein the controller is further configured to:set the first discarded count (FDC) field in the PDCP SN gap report,wherein the FDC field indicates the smallest count value among count values associated with the at least one discarded PDCP SDU.12.The UE of claim 9, wherein the controller is further configured to:allocate the discard bitmap field of length in bits equal to the number of count values from and not including a first discarded PDCP SDU up to and including the last discarded PDCP SDU.13.The UE of claim 9,wherein the PDCP SN gap report is transmitted via a PDCP control protocol data unit (PDU).14.A base station in a wireless communication system, the base station comprising:a transceiver; anda controller coupled with the transceiver, and configured to:transmit, to a user equipment (UE), a radio resource control (RRC) message for configuring a transmission of a packet data convergence protocol (PDCP) sequence number (SN) gap report, andreceive, from the UE, a PDCP SN gap report,wherein the PDCP SN gap report includes at least one of a first discarded count (FDC) field and a discard bitmap field.15.The base s tation of claim 14,wherein the FDC field indicates the smallest count value among count values associated with the at least one discarded PDCP SDU,wherein the discard bitmap field of length is allocated in bits equal to the number of count values from and not including a first discarded PDCP SDU up to and including the last discarded PDCP SDU, andwherein the PDCP SN gap report is received via a PDCP control protocol data unit (PDU).

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