Method for handling RLC operation for extended reality service in wireless network

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. Embodiments herein disclose a method for handling a radio link control (RLC) receive operation for an extended reality (XR) service in a wireless network (1000). The method includes determining, by a receiving side of an Acknowledged Mode (AM) Radio Link Control (RLC) entity of a receiver device, whether a Service Data Unit (SDU) yet to be received is outdated and to abandon a receiving of an outdated SDU. Further, the method includes handling, by the receiving side of the AM RLC entity, the RLC receive operation based on the determination.

Description

METHOD FOR HANDLING RLC OPERATION FOR EXTENDED REALITY SERVICE IN WIRELESS NETWORK

[0001] Embodiments disclosed herein relate to wireless networks (or wireless communication networks), and more particularly, to a method and system for handling a radio link control (RLC) operation for an extended reality (XR) service in the wireless network.

[0002] Fifth generation (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 6 gigahertz (GHz)" bands such as 3.5GHz, but also in "Above 6GHz" bands referred to as millimeter wave (mmWave) including 28GHz and 39GHz. In addition, it has been considered to implement sixth generation (6G) mobile communication technologies (referred to as Beyond 5G systems) in terahertz (THz) 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 multi input multi output (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 BandWidth Part (BWP), new channel coding methods such as a Low Density Parity Check (LDPC) 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 Vehicle-to-everything (V2X) 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, New Radio Unlicensed (NR-U) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, new radio (NR) user equipment (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, Integrated Access and Backhaul (IAB) 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 Dual Active Protocol Stack (DAPS) handover, and two-step random access for simplifying random access procedures (2-step random access channel (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 Augmented Reality (AR), Virtual Reality (VR), Mixed Reality (MR) 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 Orbital Angular Momentum (OAM), and Reconfigurable Intelligent Surface (RIS), 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 Artificial Intelligence (AI) 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 invention is described with consideration of Extended Reality (XR) as an applicable scenario. However, the invention is not limited to XR only. The XR is an umbrella term for different realities, including Virtual Reality (VR), Augmented Reality (AR), and Mixed Reality (MR), and is considered an essential technology to enable the realization of the digital twin / meta universe. The XR is targeted to provide a communication system framework that fulfills the challenging needs of high data rate, very low latency, and power-efficient connectivity for XR applications.

[0009] Radio Link Control (RLC) is a layer-2 sub-layer and is involved in several functionalities for the data plane processing of transmitted packets and received packets. These functionalities include, but are not limited to, the transfer of upper layer Protocol Data Units (PDUs), error correction through Automatic Repeat Request (ARQ), segmentation and reassembly of RLC service data units (SDUs), re-segmentation of RLC segments, duplicate detection, RLC SDU discard, RLC reestablishment, and protocol error detection.

[0010] For XR applications, an existing SDU discard procedure may not be efficient and effective as the XR applications are more tightly coupled with a frame transmission and not with an Internet protocol (IP) packet transmission, which is typically one-to-one mapped to the Protocol Data Convergence Protocol (PDCP) SDU and thereby to RLC SDU. Further, in the present wireless communication system (e.g., 5G system), the RLC SDU discard procedure cannot be pursued when an RLC SDU or a segment thereof has been submitted to lower layers (e.g., Medium Access Control (MAC) layer). However, transmitting the RLC SDUs which are already outdated would result in transmission resource wastage and may also delay the transmission of the following new RLC SDUs. Even if somehow the outdated RLC SDUs are not transmitted by a transmitter RLC entity, then at present, a receiver RLC entity has no mechanism to determine if the outdated RLC SDUs were not transmitted and if the receiver RLC entity needs to abandon receiving these RLC SDUs.

[0011] Hence, there is a need in the art for solutions that will overcome the aforementioned drawback(s) or shortcoming(s), among others.

[0012] The principal object of embodiments herein is to disclose a method and a RLC entity for handling a RLC operation for an extended reality (XR) service in a wireless network.

[0013] Another object of embodiments herein is to handle an RLC discard signaling for an extended reality in the wireless network.

[0014] Another object of embodiments herein is to receive RLC data packets in the wireless network.

[0015] Another object of embodiments herein is to configure a receiving side of RLC entity to discard an outdated RLC data packets in the wireless network.

[0016] Another object of embodiments herein is to disclose a method to determine an outdated RLC data packets in the wireless network.

[0017] Another object of embodiments herein is to disclose a method to discard received RLC data packets in the wireless network.

[0018] Embodiments herein is to disclose a method for handling a radio link control (RLC) receive operation for an extended reality (XR) service in a wireless network. The method includes determining, by a receiving side of an Acknowledged Mode (AM) Radio Link Control (RLC) entity of a receiver device, whether a Service Data Unit (SDU) yet to be received is outdated and to abandon a receiving of the outdated SDU. Further, the method includes handling, by the receiving side of the AM RLC entity, the RLC receive operation based on the determination.

[0019] Embodiments herein is to disclose an RLC entity of the receiver device including an XR service controller coupled with a processor and a memory. The XR service controller is configured to determine whether a SDU yet to be received is outdated and to abandon a receiving of an outdated SDU. Based on the determination, the XR service controller is configured to handle the RLC operation for the XR service.

[0020] In an embodiment, the receiver device is a User Equipment (UE). In another embodiment, the receiver device is a network entity.

[0021] In an embodiment, the method includes determining, by the receiving side of the AM RLC entity, at least one RLC SDU with a sequence number (SN) X is outdated, upon an expiry of at least one of: a reassembly timer, a local timer, and a configured timer, and at least one of: a RLC SDU with the SN has not been received and the RLC SDU with the SN has not been completely received and where the SN X of the at least one RLC SDU is less a SN Y associated with the timer.

[0022] In an embodiment, the receiving side of the AM RLC entity is configured with at least one of the timer (e.g., t-Outdated) and a parameter associating the timer with a SN Y (e.g., Rx Outdated Trigger) by a network entity in a RRC signalling message. The configuration is associated with at least one of: a per RLC entity, a per bearer, a per Logical Channel Group (LCG) and a commonly for a User Equipment (UE). The SN Y is a Rx Outdated Trigger and wherein Rx Outdated Trigger holds the highest possible value of SN following SN of the RLC SDU which triggered the discard of the RLC SDU(s) or segments of the RLC SDU(s) when the timer expires.

[0023] In an embodiment, the method includes determining, by the receiving side of the AM RLC entity, at least one byte-segment of at least one RLC SDU with the SN X has been received before the instant the receiving side of the AM RLC entity determines the RLC SDU with the SN X as outdated, where the SN X of the at least one RLC SDU is less the SN Y associated with the timer (e.g., Rx Outdated Trigger). Further, the method includes discarding, by the receiving side of the AM RLC entity, the stored at least one byte-segment of the at least one RLC SDU with the SN X based on the determination.

[0024] In an embodiment, the method includes determining, by the receiving side of the AM RLC entity, that an acknowledged mode data PDU (AMD PDU) is received from a lower layer. The AMD PDU includes at least one byte-segment of the RLC SDU with the SN X or the RLC SDU with the SN X, after the RLC SDU with SN X is determined to be outdated. Further, the method includes discarding or abandoning, by the receiving side of the AM RLC entity, the received AMD PDU based on the determination.

[0025] In an embodiment, the method includes updating, by the receiving side of the AM RLC entity, a state variable RX Highest Status to the SN Y of the first RLC SDU for which not all bytes have been received yet such that the SN Y is greater than a current RX Highest Status and which is not yet determined to be outdated when receiving the AMD PDU with the SN X and if all bytes of the RLC SDU with SN X are received. The RX Highest Status holds the highest possible value of the SN of the RLC SDU with the highest SN among received RLC SDUs.

[0026] In an embodiment, the method includes updating, by the receiving side of the AM RLC entity, the state variable RX Next to the SN Y of a first SDU for which not all bytes have been received yet such that a SN is greater than a current RX Next and which is not yet determined to be outdated, when receiving an AMD PDU with SN X and if all bytes of the RLC SDU with the SN X are received. The RX Next is a state variable that holds the value of the SN following a last in-sequence completely received RLC SDU, and the RX next serves as a lower edge of a receiving window.

[0027] In an embodiment, the method includes updating, by the receiving side of the AM RLC entity, the state variable RX Next Highest to the SN X incremented by one. The X is the sequence number of a last RLC SDU received which is determined to be outdated and X is greater than or equal to current RX Next Highest.

[0028] In an embodiment, the method includes recording, by the receiving side of the AM RLC entity, the SN X of the each of the RLC SDUs which are determined to be outdated such that the SN X is greater than current RX Next. Further, the method includes skipping, by the receiving side of the AM RLC entity, expecting to receive the outdated RLC SDUs from the transmitting entity. Further, the method includes updating, by the receiving side of the AM RLC entity, at least one state variable for SN X of each of the RLC SDUs recorded.

[0029] In an embodiment, the method includes processing, by the receiving side of the AM RLC entity, the RLC SDU when the RLC SDU or a segment of RLC SDU with the SN X is already received by the receiving RLC entity and the RLC SDU or a segment of RLC SDU with the SN X is determined to be outdated. Further, the method includes delivering, by the receiving side of the AM RLC entity, the RLC SDU to the upper layer based on the processing.

[0030] In an embodiment, the method includes avoiding to process, by the receiving side of the AM RLC entity, the RLC SDU, when the RLC SDU or the segment of RLC SDU with the SN X has already been received by the receiving RLC entity and the RLC SDU or the segment of RLC SDU with the SN X is determined to be outdated. Further, the method includes avoiding to deliver, by the receiving side of the AM RLC entity, the RLC SDU to the upper layer. Further, the method includes discarding, by the receiving side of the AM RLC entity, the already received RLC SDU or the segment of the RLC SDU.

[0031] In an embodiment, the method includes triggering to send, by the receiving side of the AM RLC entity, a status reporting to a peer AM RLC entity, when the receiving side of the AM RLC entity determines an RLC SDU is outdated and is abandoned.

[0032] In an embodiment, the method includes triggering, by the RLC entity, a status report, when at least one RLC SDU with SN X is determined to be outdated and is abandoned, where the determination is based on expiry of a timer (e.g., t-Outdated).

[0033] In an embodiment, the method includes delaying to trigger, by the receiving side of the AM RLC entity, the status report until the SN X of the outdated SDU is lesser than the RX Highest Status or the SN X is greater than or equal to summation of the RX Next and the AM window size.

[0034] In an embodiment, the method includes providing, by the receiving side of the AM RLC entity, the positive acknowledgement in a status report for the RLC SDU with the SN X, wherein the SN X is determined to be outdated and is abandoned by the receiving side of the AM RLC entity.

[0035] In an embodiment, the method includes triggering to send, by the receiving side of the AM RLC entity, a status reporting to a peer AM RLC entity without considering a delay in triggering the STATUS report until the SN X is lesser than a RX Highest Status or the SN X is greater than summation of a RX Next and an AM Window Size on the receiving side of the AM RLC entity determining an outdated RLC SDU. The RLC SDU with SN X is determined to be outdated.

[0036] In an embodiment, the method includes discarding, by the receiving side of the AM RLC entity, a RLC SDU or a segment of RLC SDU with the SN X, when the receiving side of AM RLC entity determines at least one outdated RLC SDU with the SN X, and RLC SDU or a segment of RLC SDU with SN X is received simultaneously or received within the time when status prohibit timer is running. Further, the method includes triggering, by the receiving side of the AM RLC entity, the status reporting. Further, the method includes providing, by the receiving side of an AM RLC entity, a positive acknowledgement in a status report for the RLC SDU with the SN X determined to be outdated.

[0037] In an embodiment, the method includes generating, by the AM RLC entity, a status PDU, when the receiving side of an AM RLC entity has determined an outdated SDU.

[0038] In an embodiment, the method includes starting timer (e.g., t-Outdated) and setting Rx Outdated Trigger to RX Next Highest, upon determining that the timer is not running and RX Next Highest is at least one of greater than RX Next incremented by one or is equal to RX Next incremented by one and there is at least one missing byte segment of the SDU associated with SN equals to RX Next before the last byte of all received segments of this SDU.

[0039] In an embodiment, the method includes determining whether the timer (t-Outdated) has expired and upon expiry of t-Outdated, Further, the method includes discarding byte segments of each of the RLC SDU with SN X wherein SN X is less than Rx Outdated Trigger. Further, the method includes updating RX_Next to the SN Y of the first RLC SDU with SN Y is greater than or equal to Rx Outdated Trigger for which not all bytes have been received. Further, the method includes starting timer (t-Outdated) and setting Rx Outdated Trigger to RX Next Highest, if RX Next Highest is at least one of greater than RX Next incremented by one or is equal to RX Next incremented by one and there is at least one missing byte segment of the SDU associated with SN equals to RX Next before the last byte of all received segments of this SDU.

[0040] 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 at least one embodiment 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 without departing from the scope thereof, and the embodiments herein include all such modifications.

[0041] According to embodiments of the disclosure, method for handling RLC operation for extended reality service in wireless network can be provided.

[0042] Embodiments herein are 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 following illustratory drawings. Embodiments herein are illustrated by way of examples in the accompanying drawings, and in which:

[0043] FIG. 1 illustrates a wireless network for handling an RLC operation for an XR service, according to embodiments as disclosed herein;

[0044] FIG. 2 illustrates various elements of an RLC entity of a receiver device, according to embodiments as disclosed herein;

[0045] FIG. 3 is a flow chart illustrating a method for handling the RLC operation for the XR service in the wireless network, according to embodiments as disclosed herein;

[0046] FIG. 4 illustrates an example enhanced receiver RLC entity operation to determine whether an SDU yet to be received or yet to be received completely is outdated and to abandon the receiving of the outdated SDU, according to embodiments as disclosed herein;

[0047] FIG. 5 and FIG. 6 are flow charts illustrating a method for managing outdated RLC SDU at the receiving RLC entity, according to embodiments as disclosed herein;

[0048] FIG. 7 illustrates an example RLC discard information handling approach at a receiving RLC entity for the XR service, according to embodiments as disclosed herein;

[0049] FIG. 8 illustrates an example RLC discard information handling approach at the receiving RLC entity for the XR service, according to embodiments as disclosed herein; and

[0050] FIG. 9 illustrates an example RLC discard information handling approach at the receiving RLC entity for the XR service, according to embodiments as disclosed herein.

[0051] 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 can 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] The embodiments herein disclose a method for handling a radio link control (RLC) receive operation for an extended reality (XR) service in a wireless network. The method includes determining, by a receiving side of an Acknowledged Mode (AM) Radio Link Control (RLC) entity of a receiver device, whether a Service Data Unit (SDU) yet to be received is outdated and to abandon a receiving of an outdated SDU. Further, the method includes handling, by the receiving side of the AM RLC entity, the RLC receive operation based on the determination.

[0058] Further, the embodiments herein achieve a method and system for handling a RLC discard signaling for extended reality in a wireless network. The embodiments herein achieve a method and system for receiving RLC data packets in the wireless network.

[0059] In an embodiment, the method includes transmitting a discard information in a RLC Control PDU by a transmitting RLC entity. Further, the method includes receiving discard information in an RLC control PDU by a receiving RLC entity. The method further includes processing the RLC discard information and updating RLC state variables, managing the reassembly timer, performing delivery to the upper layer and sending an updated RLC status report to the transmitting RLC entity by the receiving RLC entity.

[0060] The method can be used to achieve low latency and reliable data transfer for the XR service with improved user experience at the UE and network side.

[0061] Referring now to the drawings and more particularly to FIG 1 through FIG. 9, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.

[0062] FIG. 1 illustrates a wireless network (1000) for handling an RLC operation for an XR service, according to embodiments as disclosed herein. The wireless network (1000) can be, for example, but not limited to a fourth generation (4G) network, a fifth generation (5G) network, a sixth generation (6G) network, an Open Radio Access Network (ORAN) or the like. The wireless network (1000) includes an AM RLC entity of a transmitter device (100) and an AM RLC entity of a receiver device (200). In an embodiment, the transmitter device (100) is a UE and the receiver device (200) is a network entity. In another embodiment, the transmitter device (100) is a network device and the receiver device (200) is a UE. Further, the UE and the network entity can be both transmitting device and receiving device e.g. when the UE and the network entity are involved in bi-directional communication. That is, the UE can have both transmitting side of the RLC AM entity and the receiving side of RLC AM entity and the network entity can have both transmitting side of the RLC AM entity and receiving side of the RLC AM entity.

[0063] In an embodiment, the enhanced receiver RLC entity operation determines whether the SDU yet to be received or yet to be received completely is outdated and to abandon the receiving of an outdated SDU.

[0064] In an embodiment, an enhanced receiver RLC entity operation determines whether an SDU yet to be received is outdated and to abandon the receiving of the outdated SDU.

[0065] In an embodiment herein, the receiving side of the acknowledged mode (AM) RLC entity (200) determines a RLC SDU with SN=x is outdated upon the expiry of a reassembly timer (e.g., termed as t-Reassembly) and the RLC SDU with SN=x has not been received and / or has not been completely received.

[0066] In an embodiment herein, the receiving side of the AM RLC entity (200) determines the RLC SDU with SN=x is outdated upon the expiry of a local or a configured timer (e.g., termed as t-Outdated) and the RLC SDU with SN=x has not been received and / or has not been completely received.

[0067] In an embodiment, the receiving side of the AM RLC entity (200) is configured with at least one of a t-Outdated timer and a RX_Outdated_Trigger parameter by a network in a Radio Resource Control (RRC) signaling message (e.g., RRC reconfiguration message or the like). The configuration may be per RLC entity, per bearer, per Logical Channel Group (LCG), or commonly for the UE. In another embodiment, the state variable RX_Outdated_Trigger may be a locally configured parameter by the UE implementation.

[0068] In an embodiment herein, the t-Outdated timer may be configured with the same value as that configured for the t-Reassembly timer. In another embodiment herein, the t-Outdated timer may be configured with a larger value than that configured for the t-Reassembly timer (e.g. t-Outdated timer may be configured based on packet delay budget (PDB) or PDU-Set delay budget (PSDB), whereas the t-Reasembly timer may be configured on basis of HARQ reordering time requirements). In an embodiment herein, the t-Outdated timer may be configured with a smaller value than that configured for the t-Reassembly timer.

[0069] In an embodiment herein, the t-Outdated timer is stopped when the t-Reassembly timer expires. In another embodiment herein, the t-Reassembly timer is stopped when the t-Outdated timer expires. In another embodiment herein, the t-Outdated timer continues running when the t-Reassembly timer expires (i.e. t-Reassembly timer and t-Outdated are operated separately or independently).

[0070] In an embodiment, if at least one byte-segment of an RLC SDU with SN=x has been received before the instant, the receiving side of the AM RLC entity (200) determines the RLC SDU with SN=x as outdated, the receiving side of the AM RLC entity (200) discards the stored at least one byte-segment of the RLC SDU with SN=x.

[0071] In an embodiment herein, if an AMD PDU is received from a lower layer, wherein the AMD PDU contains at least one byte-segment of an RLC SDU with SN=x or the RLC SDU with SN=x after the RLC SDU is determined to be outdated, the receiving side of the AM RLC entity (200) discards or abandons the received AMD PDU.

[0072] In an embodiment herein, an example of the proposed specification is provided as follows:

[0073] Example 1: 5.2.3.2.2 Actions when an AMD PDU is received from lower layer (e.g., MAC layer). When the AMD PDU is received from the lower layer, where the AMD PDU contains byte segment numbers y to z of an RLC SDU with SN = x. The RLC PDU may contain a segment of the RLC SDU or a complete RLC SDU, based on the available allocation size that accommodates the RLC PDU. For example, a RLC SDU of size 100 bytes may be accommodated as two segments in two RLC PDUs - first RLC PDU has byte-segment starting from first byte to 40th byte and second RLC PDU has byte-segment starting from 41st byte to 100th byte. the receiving side of the AM RLC entity (200) shall:

[0074] - if x falls outside of the receiving window; or

[0075] - if byte segment numbers y to z of the RLC SDU with SN = x have been received before; or

[0076] - if the RLC SDU with SN = x has already been determined to be outdated:

[0077] -> discard the received AMD PDU.

[0078] - else:

[0079] -> place the received AMD PDU in a reception buffer;

[0080] -> if some byte segments of the RLC SDU contained in the AMD PDU have been received before:

[0081] -> discard the duplicate byte segments.

[0082] In an embodiment, when receiving the AMD PDU with SN = x, and if all bytes of the RLC SDU with SN = x are received, the receiving side of the AM RLC entity (200) updates a state variable RX_Highest_Status to the SN of a first RLC SDU which is not yet delivered to an upper layer (e.g., application layer), such that SN > current RX_Highest_Status (i.e., SN is greater than the current RX_Highest_Status) and which is not yet determined to be outdated. The RX Highest Status holds the highest possible value of the SN of the RLC SDU with the highest SN among received RLC SDUs

[0083] In an embodiment, when receiving the AMD PDU with SN = x, and if all bytes of the RLC SDU with SN = x are received, the receiving side of the AM RLC entity (200) updates the state variable RX_Highest_Status to the SN of the first RLC SDU which is not yet delivered to the upper layer, such that SN > current RX_Highest_Status (i.e., SN is greater than the current RX_Highest_Status) for which not all bytes have been received and which is not yet determined to be outdated.

[0084] In an embodiment, when receiving the AMD PDU with SN = x, and if all bytes of the RLC SDU with SN = x are received, the receiving side of the AM RLC entity (200) updates a state variable RX_Next to the SN of the first SDU for which not all bytes have been received yet, such that SN > current RX_Next (e.g., SN is greater than current RX_Next) and which is not yet determined to be outdated. The RX_Next is a state variable that holds the value of the SN following a last in-sequence completely received RLC SDU, and the RX_Next serves as a lower edge of the receiving window.

[0085] In an embodiment, the receiving side of the AM RLC entity (200) updates a state variable RX_Next_Highest to the SN = x+1, where x is the sequence number of the last RLC SDU received which is determined to be outdated and x >= current RX_Next_Highest. The RX_Next_Highest is a state variable that holds the value of the SN following the SN of the RLC SDU with the highest SN among received RLC SDUs.

[0086] In an embodiment, the receiving side of the AM RLC entity (200) records or marks (or performs bookkeeping) for the SN of the RLC SDUs which are determined to be outdated, such that SN > (updated) RX_Next. Further, the receiver side of the AM RLC entity (200) skips expecting to receive these outdated RLC SDUs from the transmitting entity (100) and / or assumes as if these outdated RLC SDUs are already received. Accordingly, the receiving side of the AM RLC entity (200) updates the state variables for SN of each of the RLC SDUs recorded or marked (or book-kept) as mentioned earlier. For example, when the RX_Next becomes equal to SN (i.e., RX_Next=SN), the RLC entity (200) updates RX_Next to the sequence number of the first RLC SDU with sequence number > current RX_Next for which not all bytes have been received and which is not determined to be outdated. As another example, when RX_Highest_Status becomes equal to SN (i.e., RX_Highest_Status=SN), the RLC entity (200) updates the RX_Highest_Status to the sequence number of a first RLC SDU with sequence number > current RX_Next for which not all bytes have been received and which is not determined to be outdated.

[0087] In an embodiment, when the RLC SDU or a segment of an RLC SDU with SN is already received by the receiving RLC entity (200) and it is determined to be outdated, the receiving RLC entity (200) may process the RLC SDU and / or deliver it to the upper layer.

[0088] In an embodiment, when the RLC SDU or a segment of an RLC SDU with SN has already been received by the receiving RLC entity (200) and it is determined to be outdated, the receiving RLC entity (200) may not process the RLC SDU and / or may not deliver it to the upper layer. Further, the receiving RLC entity (200) may discard the already received RLC SDU or a segment of the RLC SDU.

[0089] In an embodiment herein, a procedure for managing outdated RLC SDU at the receiving RLC entity (200) is described as below.

[0090] Example 2: For a RLC SDU with SN = x which is determined to be outdated and is abandoned, the receiving side of the AM RLC entity (200) shall:

[0091] - if x >= RX_Next_Highest:

[0092] -> update RX_Next_Highest to x+ 1.

[0093] - if x = RX_Highest_Status:

[0094] -> update RX_Highest_Status to the SN of the first RLC SDU with SN > current RX_Highest_Status for which not all bytes have been received and which is not determined to be outdated.

[0095] - if x = RX_Next:

[0096] -> update RX_Next to the SN of the first RLC SDU with SN > current RX_Next for which not all bytes have been received and which is not determined to be outdated.

[0097] - if t-Reassembly is running:

[0098] -> if RX_Next_Status_Trigger = RX_Next; or

[0099] -> if RX_Next_Status_Trigger = RX_Next + 1 and there is no missing byte segment of the SDU associated with SN = RX_Next before the last byte of all received segments of this SDU or SN=RX_Next is determined to be outdated; or

[0100] -> if RX_Next_Status_Trigger falls outside of the receiving window and RX_Next_Status_Trigger is not equal to RX_Next + AM_Window_Size:

[0101] -> stop and reset t-Reassembly.

[0102] - if t-Reassembly is not running (includes the case t-Reassembly is stopped due to actions above):

[0103] -> if RX_Next_Highest> RX_Next +1; or

[0104] -> if RX_Next_Highest = RX_Next + 1 and there is at least one missing byte segment of the SDU associated with SN = RX_Next before the last byte of all received segments of this SDU and SN = RX_Next is not determined to be outdated; or

[0105] -> start t-Reassembly;

[0106] -> set RX_Next_Status_Trigger to RX_Next_Highest.

[0107] When t-Reassembly expires, the receiving side of the AM RLC entity (200) shall:

[0108] - update RX_Highest_Status to the SN of the first RLC SDU with SN >= RX_Next_Status_Trigger for which not all bytes have been received;

[0109] - if RX_Next_Highest> RX_Next +1: or

[0110] - if RX_Next_Highest = RX_Next + 1 and there is at least one missing byte segment of the SDU associated with SN = RX_Next before the last byte of all received segments of this SDU and SN = RX_Next is not determined to be outdated:

[0111] -> start t-Reassembly;

[0112] -> set RX_Next_Status_Trigger to RX_Next_Highest.

[0113] In an embodiment herein, the receiving side of AM RLC entity starts a timer t-Outdated and seta an Rx Outdated Trigger to a RX Next Highest, upon determining that the timer t-Outdated is not running and a RX Next Highest is at least one of greater than RX Next incremented by one or is equal to RX Next incremented by one and there is at least one missing byte segment of the SDU associated with SN equals to RX Next before the last byte of all received segments of the SDU.

[0114] In an embodiment herein, the receiving side of AM RLC entity determines whether the timer t-Outdated has expired and upon expiry of the timer t-Outdated, perform at least one of: discarding byte segments of each of the RLC SDU with SN X wherein the SN X is less than Rx Outdated Trigger; updating RX_Next to the SN Y of the first RLC SDU with SN Y is greater than or equal to Rx Outdated Trigger for which not all bytes have been received; and starting the timer t-Outdated and setting Rx Outdated Trigger to RX Next Highest, if RX Next Highest is at least one of greater than RX Next incremented by one or is equal to RX Next incremented by one and there is at least one missing byte segment of the SDU associated with SN equals to RX Next before the last byte of all received segments of the SDU.

[0115] In an embodiment herein, a procedure for managing outdated RLC SDU at the receiving RLC entity (200) is described as below:

[0116] Example 3:

[0117] - if t-Outdated is running:

[0118] -> if RX_Outdated_Trigger = RX_Next; or

[0119] -> if RX_Outdated_Trigger = RX_Next + 1 and there is no missing byte segment of the SDU associated with SN = RX_Next before the last byte of all received segments of this SDU or SN=RX_Next is determined to be outdated; or

[0120] -> if RX_Outdated_Trigger falls outside of the receiving window and RX_Outdated_Trigger is not equal to RX_Next + AM_Window_Size:

[0121] -> stop and reset t-Outdated.

[0122] - if t-Outdated is not running (includes the case t-Outdated is stopped due to actions above):

[0123] -> if RX_Next_Highest> RX_Next +1; or

[0124] -> if RX_Next_Highest = RX_Next + 1 and there is at least one missing byte segment of the SDU associated with SN = RX_Next before the last byte of all received segments of this SDU and SN = RX_Next is not determined to be outdated; or

[0125] -> start t-Outdated;

[0126] -> set RX_Outdated_Trigger to RX_Next_Highest.

[0127] Whent-Outdatedexpires, the receiving side of the AM RLC entity (200) shall:

[0128] - discard all received byte-segments of RLC SDU(s), if any, of SN < RX_ Outdated_Trigger and consider SN as outdated and abandoned;

[0129] update RX_Next to the SN of the first RLC SDU with SN >= RX_Outdated_Trigger for which not all bytes have been received;

[0130] - if RX_Next_Highest> RX_Next +1: or

[0131] - if RX_Next_Highest = RX_Next + 1 and there is at least one missing byte segment of the SDU associated with SN = RX_Next before the last byte of all received segments of this SDU and SN = RX_Next is not determined to be outdated:

[0132] -> startt-Outdated;

[0133] -> set RX_Outdated_Trigger to RX_Next_Highest.

[0134] In an embodiment herein, when the receiving Unacknowledged Mode (UM) RLC entity (200) or the receiving side of the AM RLC entity (200) determines that there is at least one byte segment of the RLC SDU missing, the reassembly timer is started, and upon reassembly timer expiry, the RLC entity (200) discards all the segments of the SDU. In an embodiment herein, out-of-sequence delivery is configured or allowed for the receiving UM RLC entity (200) and / or for the receiving side of the AM RLC entity (200) as enhanced RLC configuration. Further, the receiving UM RLC entity (200) and / or the receiving side of the AM RLC entity (200) discards an incompletely received SDU (i.e., SDU segments) upon reassembly timer expiry. In an embodiment herein, out-of-sequence delivery is configured or allowed for the receiving UM RLC entity (200) and / or for the receiving side of the AM RLC entity (200) as enhanced RLC configuration. Further, the receiving UM RLC entity and / or the receiving side of the AM RLC entity (200) discards the incompletely received SDU (i.e., SDU segments) upon t-outdated timer expiry. In an embodiment herein, when the receiving side of the AM RLC entity (200) determines an RLC SDU is outdated and is abandoned, the AM RLC entity (200) triggers sending a status report (i.e., STATUS PDUs) to its peer AM RLC entity.

[0135] Example 4: The AM RLC entity (200) sends STATUS PDUs to its peer AM RLC entity (200) in order to provide positive and / or negative acknowledgements of RLC SDUs (or portions of them).

[0136] Triggers to initiate STATUS reporting include:

[0137] - When an RLC SDU with SN = x is determined to be outdated and is abandoned, the receiving side of an AM RLC entity (200) shall:

[0138] -> if x < RX_Highest_Status or x >= RX_Next + AM_Window_Size:

[0139] -> trigger a STATUS report.

[0140] -> else:

[0141] -> delay triggering the STATUS report until x < RX_Highest_Status or x >= RX_Next + AM_Window_Size.

[0142] In an embodiment herein, the receiving side of the AM RLC entity (200) provides a positive acknowledgement in the STATUS report for the RLC SDU with SN=x, which is determined to be outdated and is abandoned by the receiving side of the AM RLC entity (200).

[0143] In an embodiment herein, on the receiving side of the AM RLC entity (200) determining an outdated RLC SDU, the AM RLC entity (200) triggers sending the status report (i.e., STATUS PDUs) to its peer AM RLC entity (200) without considering a delay in triggering the status report until x < RX_Highest_Status or x >= RX_Next + AM_Window_Size, wherein an RLC SDU with SN = x is determined to be outdated.

[0144] In an embodiment herein, when the receiving side of the AM RLC entity (200) determines at least one outdated RLC SDU with SN=x and an RLC SDU or a segment of RLC SDU with SN=x is received simultaneously or received within the time when the status prohibit timer is running, the receiving side of the AM RLC entity (200) discards the RLC SDU or a segment of RLC SDU with SN=x and triggers a STATUS report. Further, the receiving side of the AM RLC entity (200) provides a positive acknowledgement in the STATUS report for the RLC SDU with SN=x determined to be outdated.

[0145] In an embodiment herein, an example of a proposed specification for building STATUS PDU when the receiving side of the AM RLC has determined an outdated SDU is provided.

[0146] Example 5: When constructing a STATUS PDU, the AM RLC entity (200) shall:

[0147] - for the RLC SDUs with SN such that RX_Next <= SN < RX_Highest_Status that has not been completely received yet, in increasing SN order of RLC SDUs and increasing byte segment order within RLC SDUs, starting with SN = RX_Next up to the point where the resulting STATUS PDU still fits to the total size of RLC PDU(s) indicated by lower layer:

[0148] -> for an RLC SDU for which no byte segments have been received yet and which is not determined to be outdated:

[0149] -> include in the STATUS PDU a NACK_SN which is set to the SN of the RLC SDU.

[0150] -> for a continuous sequence of byte segments of a partly received RLC SDU that have not been received yet and which is not determined to be outdated:

[0151] -> include in the STATUS PDU a set of NACK_SN, SOstart and SOend.

[0152] -> for a continuous sequence of RLC SDUs that have not been received yet and which is not determined to be outdated:

[0153] -> include in the STATUS PDU a set of NACK_SN and NACK range;

[0154] -> include in the STATUS PDU, if required, a pair of SOstart and SOend.

[0155] -> set the ACK_SN to the SN of the next not received RLC SDU which is not indicated as missing in the resulting STATUS PDU (i.e., also considering SN of the RLC SDU which is determined to be outdated).

[0156] In an embodiment, the receiving RLC entity (200) (e.g., receiving UM RLC entity or receiving side of AM RLC entity) receives contiguous or non-contiguous discarded RLC SDUs SN in a discard signaling. For example, a RLC discard information may include a “set” of first discarded SDU sequence number and a range of contiguous RLC SDU(s) (i.e., sequentially ordered SN RLC SDU(s)) that are discarded in a RLC Control PDU or a RLC data header or a RLC discard information may include a first discarded SDU sequence number and a bitmap for discard information in a RLC Control PDU or a RLC data header.

[0157] In an embodiment, if at least one SN value of the discarded RLC SDU included in the received RLC discard information is outside a receiving window, the receiving RLC entity (200) ignores the entire discard information included in the RLC discard signaling (e.g., RLC Control PDU). A SN falls within the receiving window if RX_Next <= SN < RX_Next+AM_Window_Size. Otherwise, the SN falls outside the receiving window.

[0158] In an embodiment, if at least one SN value of the discarded RLC SDU in the discard information is outside the receiving window, the receiving RLC entity (200) ignores only the discard information in the RLC discard signaling (e.g., RLC Control PDU) for the corresponding discarded RLC SDU(s) and processes the RLC discard information for other discarded RLC SDUs which is within the receiving window.

[0159] In an embodiment, if at least one byte segment of a RLC SDU with SN=x has been received before when the receiving side of the AM RLC entity (200) receives the RLC discard information including the discarded RLC SDU with SN=x, a receiving side of AM RLC entity (200) discards the stored at least one byte segment of the RLC SDU with SN=x.

[0160] In an embodiment herein, if a RLC SDU with SN=x has been received before when the receiving side of AM RLC entity (200) receives the RLC discard information including the discarded RLC SDU with SN=x, the receiving side of AM RLC entity (200) discards the stored RLC SDU with SN=x.

[0161] In an embodiment herein, the receiving side of AM RLC entity (200) updates the state variable RX_ Highest_Status to the SN of the first RLC SDU which is not yet delivered to an upper layer such that SN > current RX_ Highest_Status and which is either not included in the RLC Control PDU or not indicated as discarded in the RLC discard information (e.g., RLC Control PDU).

[0162] In an embodiment herein, the receiving side of AM RLC entity (200) updates the state variable RX_Next to the SN of the first SDU for which not all bytes have been received yet such that SN > current RX_Next and which is either not included in the RLC discard information (e.g., RLC control PDU) or not indicated as discarded in the RLC discard information. RX_Next is a state variable that holds the value of the SN following the last in-sequence completely received RLC SDU, and it serves as the lower edge of the receiving window.

[0163] In an embodiment herein, the receiving side of AM RLC entity (200) updates the state variable RX_Next_Highest to the SN=X+1 where X is the sequence number of the last RLC SDU received which is indicated as discarded in the RLC discard information (e.g., RLC Control PDU) and X >= current RX_Next_Highest.

[0164] In an embodiment herein, the receiving side of AM RLC entity (200) records or marks (or performs book-keeping) for the SN of the RLC SDUs which are indicated as discarded in the RLC discard information (e.g., RLC Control PDU) such that SN > (updated) RX_NEXT. Further, the receiver side of the AM RLC entity (200) skips expecting to receive these RLC SDUs from the transmitting entity (100) or assumes as if these RLC SDUs are already received. Accordingly, the receiving side of the AM RLC entity (200) updates the state variables, for SN of each of the RLC SDUs recorded or marked (or book-kept) as mentioned earlier. For example, when RX_Next becomes equal to SN (i.e., RX_Next=SN), update RX_NEXT to the sequence number of the first RLC SDU with sequence number > current RX_Next for which not all bytes have been received and which is not indicated as discarded in the RLC discard information. As another example, when RX_Highest_Status becomes equal to SN (i.e., RX_Highest_Status=SN), update RX_Highest_Status to the sequence number of the first RLC SDU with sequence number > current RX_Next for which not all bytes have been received and which is not indicated as discarded in the RLC discard information.

[0165] In an embodiment herein, when a RLC SDU or a segment of RLC SDU with SN is already received by the receiving RLC entity (200) and it is indicated as discarded in the RLC discard information (e.g., RLC Control PDU), the receiving RLC entity (200) may process the RLC SDU and / or deliver to the upper layer.

[0166] In an embodiment herein, when a RLC SDU or a segment of RLC SDU with SN has already been received by the receiving RLC entity (200) and it is indicated as discarded in the RLC Control PDU, the receiving RLC entity (200) may not process the RLC SDU and / or may not deliver to the upper layer. Further, the receiving RLC entity (200) may discard the already received RLC SDU or a segment of the RLC SDU.

[0167] In an embodiment, a procedure for managing received RLC discard information at the receiving RLC entity (200) for XR radio bearer is described as below (also illustrated in FIG. 4-FIG. 6):

[0168] Example 6: For each RLC SDU with SN = x which is indicated as discarded in the received RLC Discard information (e.g., RLC Control PDU), the receiving side of the AM RLC entity (200) shall:

[0169] - if x >= RX_Next_Highest:

[0170] - update RX_Next_Highest to x+ 1.

[0171] - if x = RX_Highest_Status:

[0172] -> update RX_Highest_Status to the SN of the first RLC SDU with SN > current RX_Highest_Status for which not all bytes have been received and which is not indicated as discarded in the RLC discard information.

[0173] - if x = RX_Next:

[0174] -> update RX_Next to the SN of the first RLC SDU with SN > current RX_Next for which not all bytes have been received and which is not indicated as discarded in the RLC discard information.

[0175] - if t-Reassembly is running:

[0176] -> if RX_Next_Status_Trigger = RX_Next; or

[0177] -> if RX_Next_Status_Trigger = RX_Next + 1 and there is no missing byte segment of the SDU associated with SN = RX_Next before the last byte of all received segments of this SDU or SN=RX_Next is indicated as discarded in the RLC discard information; or

[0178] -> if RX_Next_Status_Trigger falls outside of the receiving window and RX_Next_Status_Trigger is not equal to RX_Next + AM_Window_Size:

[0179] -> stop and reset t-Reassembly.

[0180] - if t-Reassembly is not running (includes the case t-Reassembly is stopped due to actions above):

[0181] -> if RX_Next_Highest> RX_Next +1; or

[0182] -> if RX_Next_Highest = RX_Next + 1 and there is at least one missing byte segment of the SDU associated with SN = RX_Next before the last byte of all received segments of this SDU; or

[0183] -> start t-Reassembly;

[0184] -> set RX_Next_Status_Trigger to RX_Next_Highest.

[0185] When t-Reassembly expires, the receiving side of the AM RLC entity (200) shall:

[0186] - update RX_Highest_Status to the SN of the first RLC SDU with SN >= RX_Next_Status_Trigger for which not all bytes have been received;

[0187] - if RX_Next_Highest> RX_Highest_Status +1: or

[0188] - if RX_Next_Highest = RX_Next + 1 and there is at least one missing byte segment of the SDU associated with SN = RX_Next before the last byte of all received segments of this SDU:

[0189] -> start t-Reassembly;

[0190] -> set RX_Next_Status_Trigger to RX_Next_Highest.

[0191] In an embodiment herein, when the receiving UM RLC entity or the receiving side of AM RLC entity (200) determines there is at least one byte segment of RLC SDU is missing and the reassembly timer is started and upon reassembly timer expiry, the RLC entity (200) discards all the segments of the SDU.

[0192] In an embodiment herein, out-of-sequence delivery is configured or allowed for the receiving UM RLC entity (200) and / or for the receiving side of the AM RLC entity (200) as enhanced RLC discard configuration. Further, the receiving UM RLC entity (200) and / or the receiving side of the AM RLC entity (200) discards the incompletely received SDU (i.e., SDU segments) upon reassembly timer expiry.

[0193] In an embodiment herein, when the receiving side of the AM RLC entity (200) receives an RLC discard information (e.g., RLC Control PDU), the AM RLC entity (200) triggers sending a Status reporting (i.e., STATUS PDUs) to its peer AM RLC entity.

[0194] Example 7: The AM RLC entity (200) sends STATUS PDUs to its peer AM RLC entity in order to provide positive and / or negative acknowledgements of RLC SDUs (or portions of them).

[0195] Triggers to initiate STATUS reporting include:

[0196] - RLC discard information received from its peer AM RLC entity:

[0197] -> When an RLC SDU with SN = x is included in the RLC discard information, the receiving side of the AM RLC entity (200) shall:

[0198] -> if x < RX_Highest_Status or x >= RX_Next + AM_Window_Size:

[0199] -> trigger a STATUS report.

[0200] -> else:

[0201] -> delay triggering the STATUS report until x < RX_Highest_Status or x >= RX_Next + AM_Window_Size.

[0202] In an embodiment herein, the receiving side of the AM RLC entity (200) provides a positive acknowledgement in the STATUS report for the RLC SDU with SN=x included in the received RLC discard information.

[0203] In an embodiment herein, on the receiving side of the AM RLC entity (200) receiving a RLC discard information (e.g., RLC Control PDU), the AM RLC entity (200) triggers sending a Status reporting (i.e., STATUS PDUs) to its peer AM RLC entity without considering a delay in triggering the STATUS report until x < RX_Highest_Status or x >= RX_Next + AM_Window_Size, wherein an RLC PDU with SN = x is included in the received RLC discard information.

[0204] In an embodiment herein, when the receiving side of the AM RLC entity (200) receives a RLC discard information (e.g., RLC Control PDU) including at least one discarded RLC SDU with SN=x and RLC SDU or a segment of RLC SDU with SN=x is received simultaneously or received within the time when status prohibit timer is running, the receiving side of the AM RLC entity (200) discards the RLC SDU or a segment of RLC SDU with SN=x and triggers a STATUS reporting. Further, the receiving side of the AM RLC entity (200) provides a positive acknowledgement in the STATUS report for the RLC SDU with SN=x included in the received RLC discard information.

[0205] In an embodiment herein, an example of proposed specification for building STATUS PDU, when the receiving side of AM RLC has received RLC discard information is provided:

[0206] Example 8: When constructing a STATUS PDU, the AM RLC entity (200) shall:

[0207] - for the RLC SDUs with SN such that RX_Next <= SN < RX_Highest_Status that has not been completely received yet, in increasing SN order of RLC SDUs and increasing byte segment order within RLC SDUs, starting with SN = RX_Next up to the point where the resulting STATUS PDU still fits to the total size of RLC PDU(s) indicated by lower layer:

[0208] -> for an RLC SDU for which no byte segments have been received yet and which is not indicated as discarded in the RLC discard information, if included in the RLC discard information:

[0209] -> include in the STATUS PDU a NACK_SN which is set to the SN of the RLC SDU.

[0210] -> for a continuous sequence of byte segments of a partly received RLC SDU that have not been received yet and which is not indicated as discarded in the RLC discard information, if included in the RLC discard information:

[0211] -> include in the STATUS PDU a set of NACK_SN, SOstart and SOend.

[0212] -> for a continuous sequence of RLC SDUs that have not been received yet and which is not indicated as discarded in the RLC discard information, if included in the RLC discard information:

[0213] -> include in the STATUS PDU a set of NACK_SN and NACK range;

[0214] -> include in the STATUS PDU, if required, a pair of SOstart and SOend.

[0215] - set the ACK_SN to the SN of the next not received RLC SDU which is not indicated as missing in the resulting STATUS PDU (i.e., also considering SN of the RLC SDU which is indicated as discarded in the RLC discard information, if included in the RLC discard information).

[0216] FIG. 2 shows various hardware components of the RLC entity of the receiver device (200), according to the embodiments as disclosed herein. In an embodiment, the RLC entity (200) includes a processor (210), a communicator (220), a memory (230) and an XR service controller (240). The processor (210) is coupled with the communicator (220), the memory (230) and the XR service controller (240).

[0217] Further, the XR service controller (240) determines whether the SDU yet to be received is outdated and to abandon the receiving of the outdated SDU. Based on the determination, further, the XR service controller (240) handles the RLC receive operation.

[0218] Further, the XR service controller (240) determines the at least one RLC SDU with the sequence number (SN) X is outdated, upon the expiry of at least one of: the reassembly timer, the local timer, and the configured timer, and at least one of: the RLC SDU with the SN X has not been received and the RLC SDU with the SN X has not been completely received. The SN X of the at least one RLC SDU is less a SN Y associated with the timer, wherein the SN Y is a Rx Outdated Trigger and wherein Rx Outdated Trigger holds the highest possible value of SN following SN of the RLC SDU which triggered the discard of the RLC SDU(s) or segments of the RLC SDU(s) when the timer expires.

[0219] In an embodiment, the XR service controller (240) is configured with at least one of the timer (e.g., t-Outdated) and a parameter associating the timer with a SN Y (e.g., Rx Outdated Trigger) by the network entity in a RRC signalling message. The configuration is associated with at least one of: a per RLC entity, a per bearer, a per LCG and a commonly for the UE. The SN Y is a Rx Outdated Trigger and wherein Rx Outdated Trigger holds the highest possible value of SN following SN of the RLC SDU which triggered the discard of the RLC SDU(s) or segments of the RLC SDU(s) when the timer expires.

[0220] Further, the XR service controller (240) determines at least one byte-segment of at least one RLC SDU with the SN X has been received before the instant the receiving side of the AM RLC entity (200) determines the RLC SDU with the SN X as outdated. The SN X of the at least one RLC SDU is less the SN Y associated with the timer (e.g., Rx Outdated Trigger). Further, the XR service controller (240) discards the stored at least one byte-segment of the at least one RLC SDU with the SN X based on the determination.

[0221] In an embodiment, the XR service controller (240) determines that the AMD PDU is received from the lower layer. The AMD PDU includes at least one byte-segment of a RLC SDU with a SN X or the RLC SDU with the SN X, after the RLC SDU with SN X is determined to be outdated. Based on the determination, the XR service controller (240) discards or abandons the received AMD PDU.

[0222] In an embodiment, the XR service controller (240) updates the state variable RX Highest Status to the SN Y of the first RLC SDU for which not all bytes have been received yet such that the SN Y is greater than the current RX Highest Status and which is not yet determined to be outdated when receiving the AMD PDU with the SN X and if all bytes of the RLC SDU with SN X are received.

[0223] In an embodiment, the XR service controller (240) updates the state variable RX Next to the SN Y of the first SDU for which not all bytes have been received yet such that the SN Y is greater than the current RX Next and which is not yet determined to be outdated, when receiving an AMD PDU with SN X and if all bytes of the RLC SDU with the SN X are received. The RX Next is a state variable that holds a value of the SN following a last in-sequence completely received RLC SDU, and the RX next serves as a lower edge of a receiving window.

[0224] In an embodiment, the XR service controller (240) updates the state variable RX Next Highest to the SN X incremented by one, where X is the sequence number of a last RLC SDU received which is determined to be outdated and X is greater than or equal to current RX Next Highest.

[0225] In an embodiment, the XR service controller (240) records the SN X of the each of the RLC SDUs which are determined to be outdated such that the SN X is greater than current RX Next. Further, the XR service controller (240) skips expecting to receive the outdated RLC SDUs from the transmitting entity. Further, the XR service controller (240) updates at least one state variable for SN X of each of the RLC SDUs recorded.

[0226] In an embodiment, the XR service controller (240) processes the RLC SDU when the RLC SDU or a segment of RLC SDU with the SN X is already received by the receiving RLC entity (200) and the RLC SDU or a segment of RLC SDU with the SN X is determined to be outdated. Further, the XR service controller (240) delivers the RLC SDU to an upper layer based on the processing.

[0227] In an embodiment, the XR service controller (240) avoids to process the RLC SDU, when a RLC SDU or a segment of RLC SDU with the SN X has already been received by the receiving RLC entity (200) and the RLC SDU or the segment of RLC SDU with the SN X is determined to be outdated. Further, the XR service controller (240) avoids to deliver the RLC SDU to the upper layer. Further, the XR service controller (240) discards the already received RLC SDU or a segment of the RLC SDU.

[0228] In an embodiment, the XR service controller (240) triggers to send the status reporting to a peer AM RLC entity, when the receiving side of the AM RLC entity (200) determines an RLC SDU is outdated and is abandoned.

[0229] In an embodiment, the XR service controller (240) triggers the status report, when at least one RLC SDU with SN X is determined to be outdated and is abandoned, wherein determination is based on expiry of a timer (e.g., t-Outdated).

[0230] In an embodiment, the XR service controller (240) delays to trigger the status report until the SN X of the outdated SDU is lesser than a RX Highest Status or the SN X is greater than or equal to summation of a RX Next and an AM window size.

[0231] In an embodiment, the XR service controller (240) provides the positive acknowledgement in the status report for the RLC SDU with the SN X. The SN X is determined to be outdated and is abandoned by the receiving side of the AM RLC entity (200).

[0232] In an embodiment, the XR service controller (240) triggers to send the status reporting to the peer AM RLC entity (200) without considering a delay in triggering the STATUS report until the SN X is lesser than a RX Highest Status or the SN X is greater than summation of a RX Next and an AM Window Size on the receiving side of the AM RLC entity (200) determining an outdated RLC SDU, wherein an RLC SDU with SN X is determined to be outdated.

[0233] In an embodiment, the XR service controller (240) discards the RLC SDU or the segment of RLC SDU with the SN X, when the receiving side of AM RLC entity (200) determines at least one outdated RLC SDU with the SN X, and RLC SDU or a segment of RLC SDU with SN X is received simultaneously or received within the time when status prohibit timer is running. Further, the XR service controller (240) triggers the status reporting. Further, the XR service controller (240) provides the positive acknowledgement in the status report for the RLC SDU with the SN X determined to be outdated.

[0234] In an embodiment, the XR service controller (240) generates the status PDU, when the receiving side of the AM RLC entity (200) has determined an outdated SDU.

[0235] In an embodiment, the XR service controller (240) starts the timer (e.g., t-Outdated) and sets Rx Outdated Trigger to RX Next Highest, upon determining that the timer is not running and RX Next Highest is at least one of greater than RX Next incremented by one or is equal to RX Next incremented by one and there is at least one missing byte segment of the SDU associated with SN equals to RX Next before the last byte of all received segments of this SDU.

[0236] In an embodiment, the XR service controller (240) determines whether the timer (e.g., t-Outdated) has expired and upon expiry of t-Outdated. In another embodiment, the XR service controller (240) discards the byte segments of each of the RLC SDU with SN X wherein SN X is less than Rx Outdated Trigger. In another embodiment, the XR service controller (240) updates the RX_Next to the SN Y of the first RLC SDU with SN Y is greater than or equal to Rx Outdated Trigger for which not all bytes have been received. In another embodiment, the XR service controller (240) starts the timer (e.g., t-Outdated) and sets the Rx Outdated Trigger to RX Next Highest, if RX Next Highest is at least one of greater than RX Next incremented by one or is equal to RX Next incremented by one and there is at least one missing byte segment of the SDU associated with SN equals to RX Next before the last byte of all received segments of this SDU.

[0237] The XR service controller (240) is implemented by analog and / or digital circuits such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hardwired circuits and the like, and may optionally be driven by firmware.

[0238] The processor (210) may include one or a plurality of processors. The one or the plurality of processors may be 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 AI-dedicated processor such as a neural processing unit (NPU). The processor (210) may include multiple cores and is configured to execute the instructions stored in the memory (230).

[0239] Further, the processor (210) is configured to execute instructions stored in the memory (230) and to perform various processes. The communicator (220) is configured for communicating internally between internal hardware components and with external devices via one or more networks. The memory (230) also stores instructions to be executed by the processor (210). The memory (230) may include 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 (230) 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 (532) is non-movable. In certain examples, a non-transitory storage medium may store data that can, over time, change (e.g., in Random Access Memory (RAM) or cache).

[0240] Although FIG. 2 shows various hardware components of the RLC entity (200) but it is to be understood that other embodiments are not limited thereon. In other embodiments, the RLC entity (200) may include less or more number of components. Further, the labels or names of the components are used only for illustrative purposes and does not limit the scope of the disclosure. One or more components can be combined together to perform the same or substantially similar function in the RLC entity (200).

[0241] FIG. 3 is a flow chart (S300) illustrating a method for handling an RLC receive operation for the XR service in the wireless network (1000), according to embodiments as disclosed herein. The operations (S302-S304) are handled by the XR service controller (240).

[0242] At S302, the method includes determining whether the SDU yet to be received is outdated and to abandon a receiving of the outdated SDU. At S304, the method includes handling the RLC receive operation based on the determination.

[0243] FIG. 4 illustrates an example enhanced receiver RLC entity operation (S400) to determine whether the SDU yet to be received or yet to be received completely is outdated and to abandon the receiving of the outdated SDU, according to embodiments as disclosed herein.

[0244] At step S402, the receiving RLC entity (200) is configured for outdated SDU discard configurations parameters (e.g. t-Outdated timer, RX_Outdated_Trigger parameter). At step S404, the receiving RLC entity (200) determines the RLC SDU with SN =x as outdated and abandoned, when t-Outdated timer expires with x<RX_Outdated_Trigger and discards the received byte segments of the RLC SDU, if any, At step S406, the receiving RLC entity (200) sends the positive acknowledgment (ACK) in the status report to the transmitting RLC entity (100) for the pertinent RLC SDU, which is determined to be outdated and abandoned.

[0245] FIG. 5 and FIG. 6 are flow charts (S500 and S600) illustrating a method for managing outdated RLC SDU at the receiving RLC entity (200), according to embodiments as disclosed herein.

[0246] As shown in FIG. 5, at S502, the receiving side of AM RLC entity (200) starts the timer t-Outdated and sets an Rx Outdated Trigger to a RX Next Highest, upon determining that the timer t-Outdated is not running and the RX Next Highest is at least one of greater than RX Next incremented by one or is equal to RX Next incremented by one and there is at least one missing byte segment of the SDU associated with SN equals to RX Next before the last byte of all received segments of the SDU.

[0247] As shown in FIG. 6, the operations (S602-S608) are handled by the XR service controller (240). At S602, the receiving side of AM RLC entity (200) determines whether the timer t-Outdated has expired. Upon expiry of the timer t-Outdated, at S604, the method includes discarding byte segments of each of the RLC SDU with SN X wherein the SN X is less than Rx Outdated Trigger. Upon expiry of the timer t-Outdated, at S606, the method includes updating RX_Next to the SN Y of the first RLC SDU with SN Y is greater than or equal to Rx Outdated Trigger for which not all bytes have been received. Upon expiry of the timer t-Outdated, at S608, the method includes starting the timer t-Outdated and setting Rx Outdated Trigger to RX Next Highest, if RX Next Highest is at least one of greater than RX Next incremented by one or is equal to RX Next incremented by one and there is at least one missing byte segment of the SDU associated with SN equals to RX Next before the last byte of all received segments of the SDU.

[0248] FIG. 7 illustrates an example RLC discard information handling approach (S700) at the receiving RLC entity (200) for the XR service, according to embodiments as disclosed herein. The operations (S702-S706) are handled by the XR service controller (240).

[0249] At S702, the method includes receiving RLC discard information and address each RLC SDU with the SN=x which is indicated as discarded in the received RLC discard information. At S704, the method includes checking whether x is greater than equal to RX_Next_Highest. If yes proceed to next step, at S706, the method includes updating RX_Next_Highest to X+1.

[0250] FIG. 8 illustrates an example RLC discard information handling approach (S800) at the receiving RLC entity (200) for the XR service, according to embodiments as disclosed herein. The operations (S802-S806) are handled by the XR service controller (240).

[0251] At S802, the method includes receiving the RLC discard information and address each RLC SDU with SN=x which is indicated as discarded in the received RLC discard information. At step 804, the method includes checking whether x is greater than equal to the RX_Highest_Status. If yes, proceed to next step (at step 806), the method includes updating the RX_Highest_status to the SN of the first RLC SDU with SN>current RX_Highest_Status for which not all bytes have been received and which is not indicated as discarded in the RLC discard information.

[0252] FIG. 9 illustrates an example RLC discard information handling approach (S900) at the receiving RLC entity for XR, according to embodiments as disclosed herein. The operations (S902-S906) are handled by the XR service controller (240).

[0253] At S902, the method includes receiving the RLC discard information and address each RLC SDU with SN=x which is indicated as discarded in the received RLC discard information. At S904, the method includes checking if x is greater than equal to RX_Next. If yes, proceed to the next step (i.e., at S906, the method includes updating RX_Next to the SN of the first RLC SDU with SN>current RX_Next for which not all bytes have been received and which is not indicated as discarded in the RLC discard information).

[0254] The method can be used to achieve low latency and reliable data transfer for the XR service with improved user experience at the UE and network side.

[0255] The various actions, acts, blocks, steps, or the like in the flow charts (S300-S900) may be performed in the order presented, in a different order or simultaneously. Further, in some embodiments, some of the actions, acts, blocks, steps, or the like may be omitted, added, modified, skipped, or the like without departing from the scope of the disclosure.

[0256] The embodiments disclosed herein can be implemented through at least one software program running on at least one hardware device and performing network management functions to control the network elements. The elements include blocks, which can be at least one of a hardware device or a combination of hardware device and software module.

[0257] The embodiments disclosed herein describe a method and system for receiving the RLC operation for the XR service in the wireless network (1000). Therefore, it is understood that the scope of the protection is extended to such a program and, in addition, to a computer-readable means having a message therein. Such computer-readable storage means contain program code means for implementation of one or more steps of the method when the program runs on a server or mobile device or any suitable programmable device. The method is implemented in at least one embodiment through or together with a software program written in, e.g., Very High-Speed Integrated Circuit Hardware Description Language (VHDL), another programming language, or implemented by one or more VHDL or several software modules being executed on at least one hardware device. The hardware device can be any kind of portable device that can be programmed. The device may also include means which could be, e.g., hardware means like, e.g., an ASIC or a combination of hardware and software means, e.g., an ASIC and an FPGA or at least one microprocessor and at least one memory with software modules located therein. The method embodiments described herein could be implemented partly in hardware and partly in software. Alternatively, the invention may be implemented on different hardware devices, e.g., using a plurality of CPUs.

[0258] 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 embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the scope of the embodiments as described herein.

Claims

1.A method performed by a receiver device in a wireless communication system, the method comprising:determining, based on a timer, that a radio link control (RLC) service data unit (SDU) with a sequence number (SN) X is outdated; andtransmitting, to a transmitter device, a status report including a positive acknowledgement for the RLC SDU with the SN X.2.The method of claim 1, further comprising:discarding the RLC SDU.3.The method of claim 1,wherein the RLC SDU with a sequence number (SN) X is determined to be outdated, in case that the timer expires and in case that the RLC SDU with the SN X has not been received or has not been completely received.4.The method of claim 1,wherein the timer corresponds to one of a reassembly timer, a local timer, and a configured timer, andwherein the timer and a parameter associated with the timer are configured based on a radio resource control (RRC) message.5.The method of claim 1,wherein the status report is triggered,in case that a radio link control (RLC) entity of the receiver device determines that the RLC SDU is outdated, orin case that the RLC entity of the receiver device determines that the RLC SDU with the SN X is outdated based on an expiry of the timer.6.The method of claim 1,wherein a triggering of the status report is delayed until the SN X of the outdated RLC SDU is lesser than a reception (RX) highest status or the SN X is greater than or equal to a summation of a RX next and an acknowledged mode (AM) window size, orwherein the status report is triggered without considering delay in triggering the status report until the SN X is lesser than a RX highest status or the SN X is greater than a summation of a RX next and an AM window size.7.The method of claim 1, further comprising:updating a state variable RX highest status to the SN Y of the first RLC SDU for which not all bytes have been received yet such that the SN Y is greater than a current RX highest status and which is not yet determined to be outdated in case that receiving an acknowledged mode data (AMD) protocol data unit (PDU) with the SN X and if all bytes of the RLC SDU with SN X are received, wherein RX highest status holds the highest possible value of the SN of the RLC SDU with the highest SN among received RLC SDUs;updating a state variable RX next to the SN Y of a first SDU for which not all bytes have been received yet such that a SN Y is greater than a current RX Next and which is not yet determined to be outdated, in case that receiving an AMD PDU with SN X and if all bytes of the RLC SDU with the SN X are received, wherein the RX next is a state variable that holds a value of the SN following a last in-sequence completely received RLC SDU, and the RX next serves as a lower edge of a receiving window; orupdating a state variable RX next highest to an SN X incremented by one, where X is the sequence number of a last RLC SDU received which is determined to be outdated and X is greater than or equal to current RX next highest.8.A receiver device in a wireless communication system, the receiver device comprising:a transceiver; andat least one processor coupled to the transceiver and configured to:determine, based on a timer, that a radio link control (RLC) service data unit (SDU) with a sequence number (SN) X is outdated, andtransmit, to a transmitter device, a status report including a positive acknowledgement for the RLC SDU with the SN X.9.The receiver device of claim 8,wherein the at least one processor is further configured to discard the RLC SDU.10.The receiver device of claim 8,wherein the RLC SDU with a sequence number (SN) X is determined to be outdated, in case that the timer expires and in case that the RLC SDU with the SN X has not been received or has not been completely received.11.The receiver device of claim 8,wherein the timer corresponds to one of a reassembly timer, a local timer, and a configured timer, andwherein the timer and a parameter associated with the timer are configured based on a radio resource control (RRC) message.12.The receiver device of claim 8,wherein the status report is triggered,in case that a radio link control (RLC) entity of the receiver device determines that the RLC SDU is outdated, orin case that the RLC entity of the receiver device determines that the RLC SDU with the SN X is outdated based on an expiry of the timer.13.The receiver device of claim 8,wherein a triggering of the status report is delayed until the SN X of the outdated RLC SDU is lesser than a reception (RX) highest status or the SN X is greater than or equal to a summation of a RX next and an acknowledged mode (AM) window size, orwherein the status report is triggered without considering delay in triggering the status report until the SN X is lesser than a RX highest status or the SN X is greater than a summation of a RX next and an AM window size.14.The receiver device of claim 8,wherein the at least one processor is further configured to:update a state variable RX highest status to the SN Y of the first RLC SDU for which not all bytes have been received yet such that the SN Y is greater than a current RX highest status and which is not yet determined to be outdated in case that receiving an acknowledged mode data (AMD) protocol data unit (PDU) with the SN X and if all bytes of the RLC SDU with SN X are received, wherein RX highest status holds the highest possible value of the SN of the RLC SDU with the highest SN among received RLC SDUs,update a state variable RX next to the SN Y of a first SDU for which not all bytes have been received yet such that a SN Y is greater than a current RX Next and which is not yet determined to be outdated, in case that receiving an AMD PDU with SN X and if all bytes of the RLC SDU with the SN X are received, wherein the RX next is a state variable that holds a value of the SN following a last in-sequence completely received RLC SDU, and the RX next serves as a lower edge of a receiving window, orupdate a state variable RX next highest to an SN X incremented by one, where X is the sequence number of a last RLC SDU received which is determined to be outdated and X is greater than or equal to current RX next highest.

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