Target network device, terminal device, and method

Abstract

Exemplary embodiments of the present disclosure relate to a method, an apparatus, and a computer storage medium for communications. The method includes, in a terminal device, determining from a network device at least one of the following parameters associated with a protocol data unit (PDU) set: a first parameter indicating whether all PDUs in the PDU set are required by an application layer; a second parameter indicating whether the PDU set will be discarded if additional PDU sets associated with the PDU set are lost or discarded; a third parameter indicating a discard timer for the PDU set; or a fourth parameter indicating a reordering timer for the PDU set; and processing the PDU set based on the received at least one of the parameters. In this way, packet processing at a PDU set granularity is supported, and PDU set-based processing is also supported. Therefore, communication quality and network performance are improved.

Description

Technical Field

[0001] Exemplary embodiments of the present disclosure generally relate to the field of communication technologies, and in particular, to methods, apparatuses, and computer-readable media for communication.

Background Art

[0002] In 3GPP (Registered Trademark) Release 18 (also referred to as "Rel-18"), extended reality (XR) has been attracting increasing attention. XR recognition by a terminal device (also referred to as a "UE" or "user equipment") and a network device (also referred to as a "gNB") will improve the user experience, improve the capacity of a New Radio (NR) system that supports XR services, and reduce the power consumption of the terminal device.

[0003] Due to Internet Protocol (IP) segmentation or other reasons, video frames in XR traffic may arrive at a radio access network (RAN) as a set of protocol data units (PDUs, e.g., multiple IP packets). In the case of XR / media services, a group of packets is used to carry the payload of a PDU set (meaning a "set (one group) of PDUs", e.g., a frame, a video slice / tile). Packets within such a PDU set are decoded and / or processed as a whole. PDU set-based quality of service (QoS) processing is under research and may affect the design of RAN protocols.

[0004] However, in current 5G systems (5GS: 5G systems), a single PDU within a QoS flow represents the finest granularity of QoS differentiation within a PDU session. Processing of each data packet within a QoS flow is relatively independent. Therefore, packet processing at the PDU set granularity is not supported. PDU set-based processing is also not supported for RAN and UE. Further research is needed on how to reflect PDU set information in Uu interfaces (air interfaces). [Overview of the project] [Problems that the invention aims to solve]

[0005] Generally, embodiments of the present disclosure provide, in particular, methods, apparatus, and computer storage media for communication to report similarity information between training / prediction / pre-configured beam information and field / actual beam information. [Means for solving the problem]

[0006] In a first embodiment, a method of communication is provided. The method includes a terminal device receiving from a network device at least one of the following parameters associated with a set of protocol data units (PDUs): a first parameter indicating whether all PDUs in the PDU set are required by the application layer; a second parameter indicating whether the PDU set is discarded if an additional PDU set associated with the PDU set is lost or discarded; a third parameter indicating a discard timer for the PDU set; or a fourth parameter indicating a sorting timer for the PDU set; and processing the PDU set based on the at least one of the received parameters.

[0007] In a second embodiment, a method of communication is provided. The method includes a network device determining at least one of the following parameters associated with a set of protocol data units (PDUs): a first parameter indicating whether all PDUs in the PDU set are required by the application layer; a second parameter indicating whether the PDU set is discarded if an additional set of PDUs associated with the PDU set is lost or discarded; a third parameter indicating a discard timer for the PDU set; or a fourth parameter indicating a sorting timer for the PDU set; and transmitting at least one of the parameters to a terminal device.

[0008] In some exemplary embodiments, the network device is the source network device from which the terminal device is handed over to the target network device, and the method of the second embodiment further includes sending a message for a handover request to the target network device, which provides information for preparing for the handover to the target network device, wherein the information includes at least PDU set-related information, and the PDU set-related information includes information about at least the first parameter and the second parameter.

[0009] In some exemplary embodiments, the network device is a target network device to which a terminal device is handed over from a source network device, and the method further includes receiving a message for a handover request from the source network device, which provides information for preparing the handover at the target network device, wherein the information includes at least PDU set-related information, and the PDU set-related information includes information about at least the first parameter and the second parameter.

[0010] In a third embodiment, a terminal device is provided. The terminal device comprises a processor and a memory storing computer program code. The memory and the computer program code, together with the processor, are configured to cause the terminal device to perform the method of the first embodiment.

[0011] In a fourth embodiment, a network device is provided. The network device comprises a processor and a memory storing computer program code. The memory and the computer program code, together with the processor, are configured to cause the network device to perform the method of the second embodiment.

[0012] In a fifth embodiment, a computer-readable medium storing instructions is provided. When the instructions are executed by the processor of the device, the device causes the device to perform the method of the first or second embodiment.

[0013] It should be understood that the summary portion of the invention is not intended to identify any important or fundamental features of the embodiments of this disclosure, nor to limit the scope of this disclosure. Other features of this disclosure should be readily apparent from the following description. [Brief explanation of the drawing]

[0014] The accompanying drawings further illustrate some exemplary embodiments of this disclosure, thereby further highlighting the aforementioned and other objectives, features, and advantages of this disclosure.

[0015] [Figure 1] This figure shows an exemplary communication system that can implement some embodiments of the present disclosure.

[0016] [Figure 2] This is an exemplary signaling chart relating to some exemplary embodiments of the present disclosure.

[0017] [Figure 3A] FIG. 1 is a diagram showing a first exemplary PDCP data PDU format according to some exemplary embodiments of the present disclosure.

[0018] [Figure 3B] FIG. 2 is a diagram showing a second exemplary PDCP data PDU format according to some exemplary embodiments of the present disclosure.

[0019] [Figure 3C] FIG. 3 is a diagram showing a third exemplary PDCP data PDU format according to some exemplary embodiments of the present disclosure.

[0020] [Figure 3D] FIG. 4 is a diagram showing a fourth exemplary PDCP data PDU format according to some exemplary embodiments of the present disclosure.

[0021] [Figure 3E] FIG. 5 is a diagram showing a fifth exemplary PDCP data PDU format according to some exemplary embodiments of the present disclosure.

[0022] [Figure 3F] FIG. 6 is a diagram showing a sixth exemplary PDCP data PDU format according to some exemplary embodiments of the present disclosure.

[0023] [Figure 4] FIG. 7 is an exemplary signaling diagram of a communication process according to some exemplary embodiments of the present disclosure.

[0024] [Figure 5] FIG. 8 is a flowchart of an exemplary method implemented in a terminal device according to some embodiments of the present disclosure.

[0025] [Figure 6] FIG. 9 is a flowchart of an exemplary method implemented in a network device according to some embodiments of the present disclosure.

[0026] [Figure 7] This is a schematic block diagram of an apparatus suitable for realizing the embodiments of the present disclosure.

[0027] In the diagram, identical or similar reference numbers represent identical or similar elements.

[0028] Throughout this document, the following terms may be referenced.

[0029] 3GPP 3rd Generation Partnership Project

[0030] NR New Radio Access

[0031] DCI Downlink Control Information

[0032] XR (Extended Reality)

[0033] PDCCH Physical Downlink Control Channel

[0034] MACCE (MAC Control Element)

[0035] RRC (Radio Resource Control)

[0036] PSDB PDU Set Delay Budget

[0037] PSER PDU set error rate [Modes for carrying out the invention]

[0038] Herein, the principles of the present disclosure will be illustrated with reference to several exemplary embodiments. These embodiments are provided for illustrative purposes only and should be understood as helping those skilled in the art to understand and implement the present disclosure and not to imply any limitation on the scope of the present disclosure. Embodiments described herein can be implemented in a variety of ways different from those described below.

[0039] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art.

[0040] References in this disclosure to “one embodiment,” “embodiment,” “exemplary embodiment,” etc., indicate that the described embodiment may include certain features, structures, or characteristics, but not all embodiments necessarily include such specific features, structures, or characteristics. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when describing certain features, structures, or characteristics in relation to an embodiment, it is considered that the influence of such features, structures, or characteristics in relation to other embodiments, whether or not they are explicitly described, is within the knowledge of those skilled in the art.

[0041] The terms "first," "second," etc., may be used in this specification to describe various elements, but it should be understood that these elements should not be limited by these terms. These terms are used solely to distinguish one element from another. For example, without departing from the scope of the exemplary embodiments, the first element may be named the second element, and similarly, the second element may be named the first element. As used herein, the terms "and / or" include any and all combinations of one or more of the terms described.

[0042] The terms used herein are for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments. The singular forms “one” and “the foregoing” as used herein also include the plural forms unless expressly indicated in the context. Where used herein, the terms “include,” “encompass,” “have,” “equip,” “possess,” and / or “have” specify the presence of the described features, elements, and / or components, but should be further understood not to exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0043] In some examples, values, procedures, or devices are referred to as “best,” “lowest,” “highest,” “minimum,” “maximum,” etc. Such descriptions are intended to show that a choice can be made from many commonly used functional alternatives, and it should be understood that such a choice does not necessarily have to be better, smaller, higher, or otherwise preferable than other choices.

[0044] As used herein, the term “communication network” means a network conforming to any appropriate communication standard, such as New Radio (NR), Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA®), High-Speed ​​Packet Access (HSPA), Narrow Band Internet of Things (NB-IoT), etc. Furthermore, communication between terminal devices and network devices in a communication network may be implemented in accordance with any appropriate generation of communication protocol, including but not limited to first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G), 5.5G, 5G-Advanced network, or sixth generation (6G) communication protocols, and / or any other protocols currently known or to be developed in the future. Embodiments of this disclosure can be applied to a variety of communication systems. Given the rapid development of communications, there will naturally be future types of communication technologies and systems that can embody this disclosure. This should not be considered to limit the scope of this disclosure to the aforementioned systems only.

[0045] As used herein, the term “terminal device” means any device having wireless or wired communication capabilities. Examples of terminal devices include user equipment (UE), personal computers, desktops, mobile phones, cellular phones, smartphones, personal digital assistants (PDA), portable computers, tablets, wearable devices, Internet of Things (IoT) devices, ultra-reliable and low-latency communication (URLLC) devices, Internet of Everything (IoE) devices, machine-type communication (MTC) devices, in-vehicle devices for V2X communication where X represents pedestrians, vehicles, or infrastructure / networks, devices for integrated access and backhaul (IAB), satellite-borne vehicles or aircraft-borne vehicles within non-terrestrial networks (NTN), including high-altitude platforms (HAP) encompassing satellites and unmanned aircraft systems (UAS), augmented reality (AR), and mixed reality (MR). This includes, but is not limited to, extended reality (XR) devices that include different types of reality such as Reality, virtual reality (VR), unmanned aerial vehicles (UAVs) that do not have human operators and are commonly referred to as drones, devices on high-speed trains (HST), or image acquisition devices such as digital cameras, sensors, game devices, music storage and playback devices, or internet devices that enable wireless or wired internet access and browsing.The “Terminal device” may also have multicast / broadcast capabilities and support public safety, mission-critical, V2X applications, transparent IPv4 / IPv6 multicast distribution, IPTV, smart TV, wireless services, wireless software distribution, group communications, and IoT applications. It may also incorporate one or more Subscriber Identity Modules (SIMs), known as multi-SIMs. The term “Terminal device” can be used interchangeably with UE, mobile station, subscriber equipment, mobile terminal, user terminal, or wireless device.

[0046] As used herein, the term “network device” means a device capable of providing or hosting a cell or coverage on which terminal devices can communicate. Examples of network devices include, but are not limited to, satellites, Unmanned Aerial System (UAS) platforms, Node B (NodeB or NB), Evolutionary Node B (eNodeB or eNB), Next Generation Node B (gNB), Transmission Reception Point (TRP), Remote Radio Unit (RRU), Radio Head (RH), Remote Radio Head (RRH), IAB nodes, femtonodes, piconodes and other low-power nodes, and Reconfigurable Intelligent Surfaces (RIS).

[0047] The communications described herein may conform to any appropriate standard, including but not limited to New Radio Access (NR), Long Term Evolution (LTE), LTE-Evolution, LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), cdma2000, and Global System for Mobile Communication (GSM). Furthermore, communications may be performed in accordance with any generation of communication protocols currently known or to be developed in the future. Examples of communication protocols include, but are not limited to, first-generation (1G), second-generation (2G), 2.5G, 2.85G, third-generation (3G), fourth-generation (4G), 4.5G, fifth-generation (5G), and sixth-generation (6G) communication protocols. The technologies described herein can be used in the aforementioned wireless networks and technologies, as well as in other wireless networks and technologies. Embodiments of this disclosure may be implemented in accordance with any generation of communication protocols that are currently known or may be developed in the future.Examples of communication protocols include, but are not limited to, first-generation (1G), second-generation (2G), 2.5G, 2.75G, third-generation (3G), fourth-generation (4G), 4.5G, fifth-generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or sixth-generation (6G) networks.

[0048] Terminal devices or network devices may have artificial intelligence (AI) or machine learning capabilities. Generally, this may include a trained model derived from a large amount of data collected for a specific function, which can be used to predict certain information.

[0049] Terminal or network devices may operate on several frequency ranges, such as FR1 (410 MHz to 7125 MHz), FR2 (24.25 GHz to 71 GHz), frequency bands greater than 100 GHz, and terahertz (THz). Furthermore, they can operate on licensed / unlicensed / shared spectrum. Terminal devices may have two or more connections to network devices under Multi-Radio Dual Connectivity (MR-DC) application scenarios. Terminal or network devices can operate in full-duplex, flexible-duplex, and cross-split-duplex modes.

[0050] Embodiments of the present disclosure may be implemented, for example, in test equipment such as signal generators, signal analyzers, spectral analyzers, network analyzers, test terminal devices, test network devices, or channel emulators.

[0051] Embodiments of this disclosure may be implemented in accordance with any generation of communication protocols currently known or to be developed in the future. Examples of communication protocols include, but are not limited to, the first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or sixth generation (6G) networks.

[0052] As used herein, the term “circuit” may mean a hardware circuit and / or a combination of a hardware circuit and software. For example, a circuit may be a combination of an analog and / or digital hardware circuit and software / firmware. In yet another example, a circuit may be any part of a software-equipped hardware processor, including a digital signal processor, software and one or more memories, that works together to enable a device such as a terminal or network device to perform various functions. In yet another example, a circuit may be a hardware circuit and / or a processor such as a microprocessor or a part thereof that requires software / firmware for operation, but the software may be absent if it is not required for operation. As used herein, the term “circuit” may include a hardware circuit or one or more processors alone, or a part of a hardware circuit or one or more processors and its (or their) accompanying software and / or firmware implementation.

[0053] As used herein, the singular "one" and "the foregoing" also include the plural unless explicitly indicated in the context. The term "including" and its variations should be understood as an unrestrictive term meaning "including, but not limited to." The term "based on" should be understood as "at least partially based on." The terms "one embodiment" and "embodiment" should be understood as "at least one embodiment." The term "another embodiment" should be understood as "at least one other embodiment." Terms such as "first," "second," etc., may refer to different or identical subjects. The following may include other explicit and implicit definitions.

[0054] In some examples, values, procedures, or devices are referred to as “best,” “lowest,” “highest,” “minimum,” “maximum,” etc. Such descriptions are intended to show that a choice can be made from many commonly used functional alternatives, and it should be understood that such a choice does not necessarily have to be better, smaller, higher, or otherwise preferable than other choices.

[0055] In an exemplary PDCP data PDU format following conventional schemes in this field, the PDCP data PDU format has a length of N octets and contains a 12-bit "PDCP SN" field. Specifically, the first octet contains, from left to right, the "D / C" field, three "R" (short for "reserved") fields, and the first four bits of the "PDCP SN" field. The second octet contains the remaining eight bits of the "PDCP SN" field. The remaining octets in the first format are used to store data.

[0056] In another exemplary PDCP data PDU format following conventional schemes in this field, the length of the PDCP data PDU format is also N octets, and this format has an 18-bit "PDCP SN" field. Specifically, the first octet contains, from left to right, the "D / C" field, five "R" fields, and the first two bits of the "PDCP SN" field. The second and third octets contain the remaining 16 bits of the "PDCP SN" field, each field containing 8 bits. The remaining octets in the format are used to store data.

[0057] In conventional systems, as described above, two PDCP data PDU formats are defined: one with a 12-bit PDCP SN and another with an 18-bit PDCP SN. Transmitting PDCP entities should maintain a discard timer to discard PDCP service data units (SDUs) when certain conditions are met. This timer is set only for data radio bearers (DRBs). The timer duration is set by the higher layer. In the transmitter (or, in other words, in the transmitting PDCP entity), a new timer is activated when an SDU is received from the higher layer. When the discardTimer for a PDCP SDU expires, or when the successful delivery of the PDCP SDU is confirmed by the PDCP status report, the transmitting PDCP entity should discard the PDCP SDU along with the corresponding PDCP data PDU. If the corresponding PDCP data PDU has already been submitted to the lower layer, the discard is indicated to the lower layer. Regarding SRBs, if a higher layer requests the destruction of PDCP SDUs, the PDCP entity should destroy all stored PDCP SDUs and PDCP PDUs.

[0058] Simultaneously, the receiving PDCP entity should maintain a reordering timer (e.g., named "t-Reordering") for reordering the PDUs received by the receiving PDCP entity. The duration of the timer is set by the upper layer, except in the case of NR (New Radio) sidelink communication or sidelink signaling radio bearer 4 (SRB4). In the case of NR sidelink communication or sidelink SRB4, the t-Reordering timer is determined by the implementation of the terminal device. This timer is used to detect the loss of PDCP data PDUs. When the t-Reordering timer is running, no additional t-Reordering timers should be started; that is, at any given time, only one t-Reordering timer is running per receiving PDCP entity.

[0059] In an exemplary signaling flow of a handover process following conventional methods in this field, the source gNB (source network device) issues a Handover Request message to the target gNB (target network device) that passes a transparent RRC container containing the information necessary to prepare the handover at the target gNB. The information may include, at a minimum, the target cell ID, KgNB*, the terminal device's C-RNTI at the source network device, RRM settings including the terminal device's inactivity time, basic access strum (AS) settings including antenna info ("information") and DL carrier frequency, the mapping rules from the current QoS flow to the DRB applied to the terminal device, the SIB1 from the source network device, the terminal device's capabilities for different radio access technologies (RATs), and measurement information reported by the terminal device, including PDU session-related information and, if possible, beam-related information. PDU session-related information includes slice information and QoS flow-level QoS profiles. Furthermore, the source network device may request a Dual Active Protocol Stack (DAPS) handover for one or more DRBs.

[0060] For DRBs configured to have DAPS, the source gNB sends an EARLY STATUS TRANSFER message. The DL COUNT value transmitted in the EARLY STATUS TRANSFER message indicates the PDCP SN and Hyper Frame Number (HFN) of the first PDCP SDU that the source gNB transfers to the target gNB. The source gNB continues to allocate SNs to downlink PDCP SDUs until it sends an SN STATUS TRANSFER message to the target gNB in ​​step 8b.

[0061] In U-plane processing for handover, for Radio Link Control - Acknowledgement (RLC-AM) bearers, the PDCP SN is maintained per DRB base, and the source gNB notifies the target gNB about the next DL PDCP SN to assign to packets (from the source gNB or UPF) that do not yet have a PDCP sequence number. For security synchronization, the HFN is also maintained, and the source gNB provides the target gNB with one reference HFN for UL and one reference HFN for DL, i.e., the HFN and its corresponding SN. Furthermore, for RLC-UM bearers, the PDCP SN and HFN are reset at the target gNB unless DAPS handover is configured on the bearer.

[0062] In particular, in the case of DAPS handover, both downlink and uplink operations are performed at the PDU / SDU granularity.

[0063] In some communication systems, an application layer instance may generate usable information units, for example, to construct usable information using another application layer instance. An example of such an information unit may be a video frame. Depending on its size and the Maximum Transmission Unit (MTU) of the transport network, the information unit may need to be segmented and transported across multiple transport units, such as multiple IP packets. Once all segments have been received, the receiving application layer instance uses the information unit. Therefore, the Quality of Experience (QoE) depends on the reception of the information unit (rather than the individual segments that make up the information unit). Consequently, the transport process described by QoS parameters must be associated with the information unit.

[0064] As a result, the conventional systems described above may not provide good performance. To achieve good performance, in the case of XR / media services, groups of packets are used to carry the payload of a PDU set (e.g., frame, video slice / tile). At the media layer, packets within such a PDU set are decoded and / or processed as a whole. For example, a frame / video slice may only be decoded if all or a certain amount of the packets carrying it have been successfully delivered. For example, a frame within a picture group (GOP) can only be decoded by the client if all the frames on which it depends have been successfully received. Therefore, groups of packets within a PDU set have inherent dependencies on each other at the media layer. If such dependencies between packets within a PDU set are not considered, 5GS may perform scheduling inefficiently. For example, 5GS may randomly drop packets but waste radio resources by attempting to deliver other packets from the same PDU set that are useless to the client.

[0065] In light of the above issues, this specification introduces methods, apparatus, and computer-readable media for communication to achieve better communication quality and network performance, particularly for XR services. Such solutions are described in detail below with reference to Figures 1 to 7.

[0066] Figure 1 shows an exemplary communication system 100 that can implement several embodiments of the present disclosure. The communication system 100, which is part of a communication network, includes network devices 110-1, 110-2 and terminal device 120. Hereinafter, network device 110-1 may be referred to as the first network device (or "source network device"), and network device 110-2 may be referred to as the second network device (or "target network device"). Network devices 110-1 and 110-2 may be referred to collectively as "network device 110" or "gNB 110", or individually as "network device 110" or "gNB 110".

[0067] As shown in Figure 1, network device 110 provides a coverage area including cell 101, and terminal device 120 camps in cell 101 and is served by network device 110-1. Network device 110-2 has a coverage area including cell 102. In other words, network device 110-1 provides network connectivity to terminal device 120.

[0068] In system 100, the link from network device 110 to terminal device 120 is referred to as a downlink (DL), and the link from terminal device 120 to network device 110 is referred to as an uplink (UL). In a downlink, network device 110 is a transmitting (TX) device (or transmitter), and terminal device 120 is a receiving (RX) device (or receiver). In an uplink, terminal device 120 is a transmitting TX device (or transmitter), and network device 110 is an RX device (or receiver). It should be understood that network device 110 may provide one or more serving cells. In some embodiments, network device 110 can provide multiple cells.

[0069] The network device 110-1 may provide services to the terminal device 120, and the network device 110-1 and the terminal device 120 may communicate data and control information with each other. In other words, the network device 110-1 is a serving network device for the terminal device 120.

[0070] Communication in the communication system 100 may comply with any appropriate standard, including but not limited to Long Term Evolution (LTE), LTE-Evolution, LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), and Global System for Mobile Communication (GSM). Furthermore, communication may be performed in accordance with any generation of communication protocol that is currently known or will be developed in the future. Examples of communication protocols include, but are not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G), 5.5G, 5G-Advanced network, or sixth generation (6G) communication protocols.

[0071] It should be understood that the number of devices shown in Figure 1, as well as their connections and types, are given for illustrative purposes only and do not imply any limitation. The communication system 100 may include any suitable number of network devices and terminal devices suitable for carrying out embodiments of the present disclosure.

[0072] Furthermore, the following points should be noted.

[0073] In this disclosure, the term “PDU set” means, for example, that a PDU set consists of one or more PDUs carrying the payload of one information unit generated at the application level (e.g., a frame or video slice for an XRM service used in 3gpp TR26.926

[27] ). In some implementations, all PDUs in a PDU set are required by the application layer to use the corresponding information unit. In other implementations, even if some PDUs are missing, the application layer can recover some or all of the information unit.

[0074] In this disclosure, the term "data burst" means a set of data containing multiple PDUs that are generated and transmitted in a short period of time by an application, for example. A data burst may consist of one or more sets of PDUs.

[0075] In this disclosure, the term "PSDB" means, for example, a PDU Set Delay Budget that defines an upper limit on the time a PDU set may be delayed between the terminal device 120 and the N6 termination point in the User-Plane Function (UPF). The PSDB applies to DL PDU sets received by the UPF via the N6 interface and UL PDU sets transmitted by the terminal device 120.

[0076] In this disclosure, the term "PSER" means, for example, the PDU Set Error Rate (PSER), which defines an upper limit on the percentage of PDU sets (e.g., a set of IP packets constituting a PDU set) that have been processed by the sender of a link-layer protocol (e.g., Radio Link Access (RLC) in a RAN for 3GPP access) but in which not all PDUs within the PDU set have been successfully delivered to a higher layer (e.g., PDCP in a RAN for 3GPP access). Thus, PSER defines an upper limit on the non-congestion-related packet loss rate. The purpose of PSER is to enable proper link-layer protocol configuration (e.g., RLC and Hybrid Automatic Repeat Request (HARQ) in a RAN for 3GPP access).

[0077] Figure 2 shows an exemplary signaling chart illustrating a communication process 200 according to some exemplary embodiments of the present disclosure. For illustrative purposes only, the communication process 200 will be described with reference to Figure 1. The communication process 200 may involve a terminal device 120 and a network device 110.

[0078] In some exemplary embodiments, the network device 110 determines at least one of the following parameters associated with a set of Protocol Data Units (PDUs): a first parameter indicating whether all PDUs in the PDU set are required by the application layer; a second parameter indicating whether a PDU set is discarded if an additional PDU set associated with the PDU set is lost or discarded; a third parameter indicating a discard timer for the PDU set; or a fourth parameter indicating a sorting timer for the PDU set.

[0079] For example, regarding the control plane, the network device 110 can determine at least one of the following parameters for the terminal device 120 by RRC signaling, as shown in Figure 2 (210).

[0080] ● Whether all PDUs belonging to the PDU set are required: Based on this parameter, the receiving PDCP entity can decide whether to discard all PDUs belonging to a PDU set if at least one PDU in that set is lost.

[0081] ● If a high-priority (or associated) PDU set is lost / discarded, should other PDU sets associated with that PDU set also be discarded?

[0082] ● PDU set discard timer (e.g., named "discardTimer"): This timer is set only for the DRB. In the transmitting PDCP entity, a new PDCP set discard timer is activated upon the first reception of PDUs from a PDCP set from a higher layer. When this timer expires, the terminal device 120 discards all PDUs belonging to the corresponding PDU set and / or all PDUs in other PDU sets associated with this PDU set. All PDUs within the same PDU set share the same PDU set discard timer.

[0083] ● PDU set reordering timer (e.g., named "t-Reordering"): This timer is set up only for DRB. This timer is used to detect the loss of PDCP data PDUs belonging to the corresponding PDU set.

[0084] Furthermore, in some exemplary embodiments, the network device 110 transmits at least one of the parameters to the terminal device 120.

[0085] For example, with respect to the control plane, the network device 110 may transmit at least one of the parameters (represented as 201 in Figure 2) to the terminal device 120 (for example, by RRC signaling) (220), as shown in Figure 2.

[0086] On the other side of the communication, the terminal device 120 receives at least one parameter 201 (222). Using the received parameter, such a parameter may be set in the terminal device 120.

[0087] Furthermore, in some exemplary embodiments, the terminal device 120 processes the PDU set based on at least one of the received parameters 201.

[0088] For example, terminal device 120 may process the PDU set (e.g., drop / discard the PDU set) based on at least one of the received parameters 201 (230).

[0089] To facilitate the processing of PDU sets by the terminal device 120, multiple fields may be defined in the PDCP data PDU. In some exemplary embodiments, packets from higher layers are organized in units of PDU sets at the PDCP layer, and PDU set information is transmitted in the band within the PDCP header of each PDU in the PDU set.

[0090] For example, as can be seen from the examples shown in Figures 3A to 3F, packets from higher layers are organized into PDU sets at the PDCP layer, and PDU set information is transmitted within the band in the PDCP header of each PDU within the PDU set. This will be explained in detail with reference to Figures 3A to 3F.

[0091] Figure 3A shows an exemplary PDCP data PDU format (hereinafter referred to as the "First Format") relating to some exemplary embodiments of the present disclosure.

[0092] In some exemplary embodiments, the header of a PDCP data PDU includes at least one of the following fields: a first field indicating the serial number (SN) of the PDU set to which the PDCP data PDU belongs; a second field indicating whether the PDCP data PDU is the first PDU in the PDU set to which it belongs; or a third field indicating whether the PDCP data PDU is the last PDU in the PDU set to which it belongs.

[0093] For example, a PDCP data PDU format having a 12-bit PDCP SN (for PDU sets) is shown in Figure 3A. According to the first format, at least one of the following fields may be defined in the header of the PDCP data PDU.

[0094] "PDU set SN" field: This field indicates the serial number (SN) of the PDU set to which the PDCP data PDU belongs.

[0095] "Start Indication" field: This field indicates whether the PDCP data PDU is the first PDU in the PDU set to which it belongs. If the value of this field is set to "0", it indicates that the PDCP data PDU is not the first PDU in the PDU set to which it belongs. If the value of this field is set to "1", it indicates that the PDCP data PDU is the first PDU in the PDU set to which it belongs.

[0096] "End Indication" field: This field indicates whether this PDCP data PDU is the last PDU in the PDU set to which it belongs. If the value of this field is set to "0", it indicates that this PDCP data PDU is not the last PDU in the PDU set to which it belongs. If the value of this field is set to "1", it indicates that this PDCP data PDU is not the last PDU in the PDU set to which it belongs.

[0097] In some exemplary embodiments, each of the second and third fields uses one bit in the PDCP header. For example, as shown in Figure 3A, the "start instruction" field and the "end instruction" field may each use one reserved bit in the PDCP header.

[0098] Furthermore, or alternatively, the length of the "PDU set SN" field may be 1 octet, or 8 bits, as shown in Figure 3A.

[0099] Figure 3B shows another exemplary PDCP data PDU format (hereinafter referred to as the "Second Format") relating to some exemplary embodiments of the present disclosure.

[0100] In some exemplary embodiments, the header of a PDCP data PDU includes at least one of the following fields: a first field indicating the serial number (SN) of the PDU set to which the PDCP data PDU belongs; a second field indicating whether the PDCP data PDU is the first PDU in the PDU set to which it belongs; or a third field indicating whether the PDCP data PDU is the last PDU in the PDU set to which it belongs.

[0101] For example, a PDCP data PDU format having an 18-bit PDCP SN (for PDU sets) is shown in Figure 3B. According to the second format, at least one of the following fields should be defined in the header of the PDCP data PDU: the "PDU setting SN" field, the "start instruction" field, and the "end instruction" field.

[0102] Similar to the example shown in Figure 3A, in the example shown in Figure 3B, the second field ("start instruction" field) and the third field ("end instruction" field) may also each use one bit reserved in the PDCP header. Furthermore, or alternatively, the length of the "PDU set SN" field may be one octet, i.e., 8 bits, as shown in Figure 3B.

[0103] Figure 3C shows an exemplary PDCP data PDU format (hereinafter referred to as the "Third Format") relating to some exemplary embodiments of the present disclosure. For illustrative purposes only, the Third Format will be described with reference to Figure 3A.

[0104] In some exemplary embodiments, the header of the PDCP data PDU further defines at least one of the following fields: a fourth field indicating the SN of another PDU set, wherein the PDU set to which the PDCP data PDU belongs is associated with the PDU set identified by that field; a fifth field indicating whether the fourth field is present in the header of the PDCP data PDU; or a sixth field indicating the importance or priority of the PDU set.

[0105] For example, a PDCP data PDU format having a 12-bit PDCP SN (for PDU sets) is shown in Figure 3C. According to the third format, at least one of the following fields may be further defined in the header of the PDCP data PDU.

[0106] The "Correlation PDU Set SN" field (optional): This field indicates the SN of other PDU sets, and the PDU set to which the PDCP data PDU belongs is associated with the PDU set identified by this field. For example, if at least one PDU in the PDU set indicated by the "Correlation PDU Set SN" field is lost / discarded, the PDU set to which this PDCP data PDU belongs should also be discarded / dropped.

[0107] "T" field (optional): This field indicates whether the "Correlated PDU Set SN" field exists in the PDCP header. If the value of the "T" field is set to 0, it indicates that the "Correlated PDU Set SN" field does not exist in the PDCP header. If the value of the "T" field is set to 1, it indicates that the "Correlated PDU Set SN" field exists in the PDCP header.

[0108] The "PDU Set importance level information" field (or priority or PDU set type; optional): This field contains importance or priority information for the PDU set. For example, the importance level (or priority) of PDU sets corresponding to I-frames (short for "Independent frame," a single frame of digital content that the compressor inspects independently of the preceding and succeeding frames and stores all the data necessary to display that frame) and P-frames (short for "Predicted frame," which only holds changes in the image from the previous frame) will be different. The importance level (or priority) of PDU sets corresponding to the Base Layer (BL) and Enhanced Layer (EL) will also be different, and so on.

[0109] In some exemplary embodiments, the fifth field uses one bit in the PDCP header. Depending on whether the fifth field indicates that the fourth field is present in the PDCP header, the fourth field is newly added to the PDCP header.

[0110] For example, the fifth field ("T" field) reuses a reserved bit in the PDCP header. A "T" field set to 1 may indicate that the "Correlated PDU Set SN" field is present in the PDCP header, and a "T" field set to 0 may indicate that the "Correlated PDU Set SN" field is present in the PDCP header. In this case, the fourth field (i.e., the "Correlated PDU Set SN" field) is newly added to the PDCP header, depending on whether the "T" field indicates that the fourth field is present in the PDCP header (i.e., the "T" field is set to 1).

[0111] Figure 3D shows another exemplary PDCP data PDU format (hereinafter referred to as the "Fourth Format") relating to some exemplary embodiments of the present disclosure. For illustrative purposes only, the Fourth Format will be described with reference to Figure 3B.

[0112] For example, a PDCP data PDU format having an 18-bit PDCP SN (for PDU sets) is shown in Figure 3D. According to the fourth format, at least one of the following fields may be defined in the header of the PDCP data PDU: the "Correlated PDU Set SN" field (optional), the "T" field (optional), and the "PDU Set Importance Level Information" field.

[0113] In some exemplary embodiments, the fifth field uses one bit in the PDCP header. Depending on whether the fifth field indicates that the fourth field is present in the PDCP header, the fourth field is newly added to the PDCP header.

[0114] For example, the fifth field ("T" field) reuses a reserved bit in the PDCP header. A "T" field set to 1 may indicate that the "Correlated PDU Set SN" field is present in the PDCP header, and a "T" field set to 0 may indicate that the "Correlated PDU Set SN" field is present in the PDCP header. In this case, the fourth field (i.e., the "Correlated PDU Set SN" field) is newly added to the PDCP header, depending on whether the "T" field indicates that the fourth field is present in the PDCP header (i.e., the "T" field is set to 1).

[0115] Figure 3E shows an exemplary PDCP data PDU format (hereinafter referred to as the "Fifth Format") relating to some exemplary embodiments of the present disclosure. For illustrative purposes only, the Fifth Format will be described with reference to Figure 3A.

[0116] For example, a PDCP data PDU format with a 12-bit PDCP SN (for PDU sets) is shown in Figure 3E. According to the fifth format, compared to the first format, an "Imp" field indicating PDU set importance level information is further defined in the header of the PDCP data PDU. As mentioned above, this field contains importance or priority information for the PDU set. For example, the importance level (or priority) of PDU sets corresponding to I-frames and P-frames is different. The importance level (or priority) of PDU sets corresponding to BL layers and EL layers is different, and so on.

[0117] In some exemplary embodiments, the sixth field uses at least one bit in the PDCP header.

[0118] For example, as shown in Figure 3E, the sixth field (the "PDU Set Importance Level Information" field, or simply the "Imp" field, as shown in Figure 3E) reuses reserved bits in the PDCP header, as shown in Figure 3A.

[0119] Figure 3F shows another exemplary PDCP data PDU format (hereinafter referred to as the "Sixth Format") relating to some exemplary embodiments of the present disclosure. For illustrative purposes only, the Sixth Format will be described with reference to Figure 3B.

[0120] For example, a PDCP data PDU format with an 18-bit PDCP SN (for PDU sets) is shown in Figure 3F. According to the sixth format, compared to the second format, an "Imp" field indicating PDU set importance level information is further defined in the header of the PDCP data PDU. As mentioned above, this field contains importance or priority information for the PDU set. For example, the importance level (or priority) of PDU sets corresponding to I-frames and P-frames is different. The importance level (or priority) of PDU sets corresponding to BL layers and EL layers is different, and so on.

[0121] In some exemplary embodiments, the sixth field uses at least one bit in the PDCP header.

[0122] For example, the sixth field (the "PDU Set Importance Level Information" field, or simply the "Imp" field, as shown in Figure 3E) reuses reserved bits in the PDCP header.

[0123] In some exemplary embodiments, the terminal device further determines the range of counts or PDCP SNs belonging to a PDU set from a first count or first PDCP SN, which is a count or PDCP SN of a PDCP data PDU with the second field set to 1, to a second count or second PDCP SN, which is a count or PDCP SN of a PDCP data PDU with the third field set to 1, and determines whether the PDCP set has lost at least one PDU based on the information regarding the PDU set SN, the count or PDCP SN, the second field and the third field.

[0124] For example, in the examples shown in Figures 3A to 3F, the range of COUNT (or PDCP SN) belonging to the PDU set is [COUNT (or PDCP SN) of PDCP data PDUs with the start instruction field set to 1, and COUNT (or PDCP SN) of PDCP data PDUs with the end instruction field set to 1]. The terminal device 120 and / or network device 110 can determine whether the PDCP set has lost any PDUs according to the "PDU set SN", COUNT (or "PDCP SN"), "start instruction", and "end instruction" fields.

[0125] In this case, if no PDCP data PDUs have been received for a PDU set in which the "Start Instruction" field is set to 1, or the "End Instruction" field is set to 1, it can be inferred that the PDCP set has lost at least one PDU.

[0126] Furthermore, if a PDU set receives both a PDCP data PDU with the "Start Instruction" field set to 1 and a PDCP data PDU with the "End Instruction" field set to 1, the PDCP receiving entity can determine the COUNT (or PDCP SN) range of the PDU set based on these PDCP data PDUs. If any PDCP PDU within this range is lost, the receiving PDCP entity can know that the PDU set has lost at least one PDU.

[0127] Thus, based on the PDCP data PDU structure (for example, as shown in Figures 3A to 3F), the PDCP SN (or COUNT) value remains continuous as before, and existing COUNT-based procedures (e.g., encryption / integrity protection / sorting) can be reused. At the same time, PDU set-related procedures may be executed based on conventional COUNT-based procedures, such as discarding PDU sets or determining whether any PDUs in a PDU set have been lost.

[0128] In some exemplary embodiments, upon initial reception of a PDCP SDU belonging to a PDU set from a higher layer, the transmitting PDCP entity (for example, in terminal device 120) activates the discard timer associated with that PDU set. When the discard timer expires for an SDU set, it discards the PDU and / or SDU belonging to the corresponding PDU set, and / or the PDU and / or SDU of other PDU sets associated with that PDU set. Here, PDUs within the same PDU set share the same discard timer.

[0129] For example, in a PDU set discard timer-based drop / discard scenario, the PDU set discard timer (e.g., named "discardTimer") is defined as a timer set only for the DRB. All PDUs within the same PDU set share the same PDU set discard timer. Upon initial reception of PDCP SDUs belonging to a PDCP set from a higher layer, the transmitting PDCP entity (e.g., in terminal device 120) should activate the PDU set discard timer associated with this PDU set (if set). When the PDU set discard timer for a PDU set expires, the transmitting PDCP entity should discard all PDUs / SDUs belonging to the corresponding PDU set, and / or all PDUs / SDUs in other PDU sets associated with this PDU set. If the corresponding PDCP data PDU has already been submitted to a lower layer, the discard is indicated to the lower layer. For example, if PDU set N (the PDU set with set index "N") is discarded, the transmitting PDCP entity should also discard any PDU sets where the "correlated PDU set SN" field is equal to N.

[0130] There are two alternatives for buffering data belonging to a PDU set. One approach is to deliver all PDCP SDUs in a PDU set to the upper layer only when all PDUs belonging to that set have been received. Otherwise, the data in the PDU set should be stored in the receive buffer for sorting. The other approach is to store only the out-of-order data in the receive buffer as before.

[0131] In some exemplary embodiments, upon first reception of a PDU belonging to a PDU set from a lower layer, the receiving PDCP entity (for example, in terminal device 120) activates the sorting timer associated with that PDU set. When the sorting timer expires for an SDU set, it discards the PDUs and / or SDUs belonging to the corresponding PDU set, and / or PDUs and / or SDUs from other PDU sets associated with that PDU set. Here, PDUs within the same PDU set share the same sorting timer.

[0132] For example, the PDU set t-Reordering timer is defined as a reordering timer for a PDU set and is set by RRC signaling. This timer is set only for the DRB and is used to detect the loss of PDCP data PDUs belonging to the corresponding PDU set. All PDUs within the same PDU set share the same PDU set t-Reordering timer. In a receiving PDCP entity (for example, in terminal device 120), a new PDCP PDU set reordering timer (i.e., t-Reordering timer) is activated upon the first reception of PDCP PDUs belonging to a PDCP set from a lower layer. If the PDU set t-Reordering expires for a PDU set and at least one PDU / SDU in the PDCP set is lost, the receiving PDCP entity should discard all PDU / SDUs belonging to this PDU set, and / or all PDU / SDUs in other PDU sets associated with this PDU set. For example, if PDU set N (the PDU set whose set index is "N") is lost, the receiving PDCP entity should also discard any PDU sets whose "Correlated PDU Set SN" field is equal to N.

[0133] Specifically, in this case, the following processing flow may be executed based on the above explanation. TIFF0007899951000001.tif63168TIFF0007899951000002.tif44168

[0134] Furthermore, or alternatively, the following processing flow may be performed. TIFF0007899951000003.tif39168TIFF0007899951000004.tif30168

[0135] Specifically, in some exemplary embodiments, if a request is made from a higher layer to pause the transmission of a PDU set, while the sorting timer is running, the receiving PDCP entity in terminal device 120 further stops and resets the sorting timer.

[0136] For example, if the upper layer requests a PDCP entity to pause (sending PDU sets), the receiving PDCP entity (for example, in terminal device 120) will:

[0137] - If t-Reordering or PDU set t-Reordering is running,

[0138] - Stop and reset t-Reordering or PDU Set t-Reordering,

[0139] After performing header decompression, all stored PDCP SDUs are delivered to the upper layer in ascending order of their associated COUNT values.

[0140] - Set RX_NEXT and RX_DELIV to their initial values.

[0141] In some other exemplary embodiments, if the sort timer value is set by a higher layer, the receiving PDCP entity in terminal device 120 further stops and restarts the sort timer while it is running.

[0142] For example, if a higher layer requests a pause from a PDCP entity, the receiving PDCP entity (for example, in terminal device 120) will:

[0143] If the value of PDU set t-Reordering is reset by a higher layer while PDU set t-Reordering is being executed, the received PDCP entity in terminal device 120 will

[0144] - Update RX_REORD to RX_NEXT,

[0145] - PDU set t-Reordering should be stopped and restarted.

[0146] In some exemplary embodiments, when the discard timer for a PDCP SDU expires, the transmitting PDCP entity in the terminal device 120 discards the PDU and / or SDU belonging to the corresponding PDU set, and / or the PDU and / or SDU of other PDU sets associated with that PDU set.

[0147] For example, if the discardTimer expires for a PDCP SDU, the transmitting PDCP entity (e.g., in terminal device 120) should discard all PDUs / SDUs belonging to the corresponding PDU set, and / or all PDUs / SDUs in other PDU sets associated with this PDU set. If the corresponding PDCP data PDU has already been submitted to a lower layer, the discard is indicated to the lower layer.

[0148] In some exemplary embodiments, depending on whether all PDUs in a PDU set are required by the application layer and at least one PDU and / or SDU in a PDCP set is configured to be lost, the receiving PDCP entity (e.g., in terminal device 120) discards the PDU and / or SDU belonging to the corresponding PDU set and / or PDU / SDU of other PDU sets associated with that PDU set when the sorting timer for the PDCP SDU expires.

[0149] For example, if RRC signaling is configured to require all PDUs belonging to a PDU set from the application layer, and at least one PDU / SDU from a PDCP set is lost upon t-Reordering expiration, the receiving PDCP entity (e.g., in terminal device 120) should discard all PDUs / SDUs belonging to this PDU set and / or all PDUs / SDUs from other PDU sets associated with this PDU set.

[0150] The following explanation describes how PDU set information is handled during the handover procedure.

[0151] Figure 4 shows an exemplary signaling diagram of a communication process 400 according to some exemplary embodiments of the present disclosure. For illustrative purposes only, the process 400 will be described with reference to Figure 1. Specifically, the communication process 400 may be a handover process and may include a terminal device 120, a source network device 110-1, and a target network device 110-2.

[0152] In the handover process, which is the communication process 600, as described above, it is assumed that network device 110-1 is the source network device currently providing network services to terminal device 120, and network device 110-2 is the target network device that can provide network services to terminal device 120 from the time of handover, while source network device 110-1 will no longer provide network services to terminal device 120 from the time of handover. In other words, network services to terminal device 120 can be "handed over" from source network device 110-1 to target network device 110-2.

[0153] In some exemplary embodiments, during the handover execution period, the terminal device 120 further maintains a common PDU set SN assignment. Here, the continuity of the PDU set SN is supported for both RLC-AM and Unacknowledgement (UM) DRBs for which DAPS is set.

[0154] In some exemplary embodiments, source network device 110-1 further sends a message for a handover request to target network device 110-2, which provides information for preparing for a handover to the target network device. This information includes at least PDU set-related information, which includes information about at least a first parameter and a second parameter.

[0155] In some exemplary embodiments, the source network device 110-1 further maintains the PDU set serial number (SN) for the RLC-AM bearer and transmits to the target network device the next PDU set SN to be assigned to packets that do not have a PDU set SN.

[0156] In some exemplary embodiments, the source network device 110-1 further transmits to the target network device 110-2 information relating to at least one of a first field, a second field, a third field, or the size of the PDU set.

[0157] In some exemplary embodiments, the source network device 110-1 further transmits information to the target network device 110-2 regarding the importance level or priority, or the associated PDU set.

[0158] In some exemplary embodiments, source network device 110-1 further sends a message for early state transfer to target network device 110-2 if DAPS is configured on the DRB. The PDU set SN and / or downlink count values ​​transmitted in the message indicate the PDU set SN, PDCP SN, and HFN of a first PDCP SDU that source network device 110-1 transfers to target network device 110-2.

[0159] In some exemplary embodiments, the source network device 110-1 further assigns the SN and / or PDU set SN to the downlink PDCP SDU until the source network device 110-1 sends a message for SN state transfer to the target network device 110-2.

[0160] In some exemplary embodiments, the message for SN state transfer indicates to the target network device 110-2 the PDU set SN and count of a first missing PDCP SDU that the target network device 110-2 should begin delivering.

[0161] In some exemplary embodiments, source network device 110-1 further assigns downlink PDCP SN and / or PDU set SN until the SN assignment is handed over to target network device 110-2, schedules downlink data on the source radio link when source network device 110-1 assigns downlink PDCP SN and / or PDU set SN, and begins transferring the downlink PDCP SDU along with the assigned PDCP SN and / or PDU set SN to target network device 110-2, and maintains the PDU set SN, HFN, and PDCP SN after the SN assignment has been handed over to target network device 110-2.

[0162] In some exemplary embodiments, the source network device 110-1 further transmits to the target network device 110-2 information relating to at least one of a first field, a second field, a third field, or the size of the PDU set.

[0163] In some exemplary embodiments, the source network device 110-1 further transmits information to the target network device 110-2 regarding the importance level or priority, or the associated PDU set.

[0164] In some exemplary embodiments, the source network device 110-1 further sends a message for a handover request to the target network device 110-2, which includes PDU set-related information including information about at least a first parameter and a second parameter, and sends a message for SN state transfer to the target network device 110-2.

[0165] In some exemplary embodiments, source network device 110-1 further requests a DAPS handover for one or more DRBs and sends a message to target network device 110-2 for early state transfer for the DRBs in which DAPS is configured. This message includes the values ​​of PDU set SN and / or downlink count indicating the PDU set SN, PDCP SN and HFN of a first PDCP SDU that source network device 110-1 transfers to target network device 110-2.

[0166] In some exemplary embodiments, for DRBs where DAPS is not configured, the source network device 110-1 further sends a message for SN status transfer to the target network device 110-2.

[0167] In some exemplary embodiments, the target network device 110-2 further receives a message from the source network device 110-1 for a handover request, which provides information for preparing the handover at the target network device 110-2. This information includes at least PDU set-related information, which includes information about at least a first parameter and a second parameter.

[0168] In some exemplary embodiments, when it is determined that a DAPS handover is configured for a Radio Link Control-Acknowledgement (RLC-UM) bearer, the target network device 110-2 further resets the PDU set SN, PDCP SN, and HFN for the RLC-UM bearer.

[0169] As shown in Figure 4, in step 3, the source gNB (i.e., source network device 110-1) issues a handover request message to the target gNB (i.e., target network device 110-2) that passes a transparent RRC container containing the information necessary to prepare the handover on the target side. The information includes at least the target cell ID, KgNB*, the C-RNTI of terminal device 120 at source network device 110-1, RRM settings including inactivity time of terminal device 120, basic AS settings including antenna info and DL carrier frequency, the mapping rules from current QoS flow to DRB applied to terminal device 120, SIB1 from source network device 110-1, the capabilities of terminal device 120 for different RATs, PDU session-related information, PDU set-related information (optional, this information may be in the QoS profile), and, if possible, measurement information reported by the UE, including beam-related information. PDU session-related information includes slice information and QoS flow level QoS profile. PDU set-related information includes whether all PDUs are required for the PDU set, whether or not to drop PDUs, and how to drop them. The source gNB may also request DAPS handovers for one or more DRBs.

[0170] Furthermore, as shown in Figure 4, in step 7a, the source gNB (i.e., source network device 110-1) sends an EARLY STATUS TRANSFER message for the DRB on which DAPS is configured. The PDU set SN / DL COUNT value transmitted in the EARLY STATUS TRANSFER message indicates the PDU set SN, PDCP SN, and HFN of the first PDCP SDU that the source gNB (i.e., source network device 110-1) transfers to the target gNB (i.e., target network device 110-2). The source gNB does not stop allocating the SN / PDU set SN to the downlink PDCP SDU until it sends an SN STATUS TRANSFER message to the target gNB in ​​step 8b.

[0171] In step 7, for DRBs where DAPS is not configured, the source gNB sends an SN STATUS TRANSFER message to the target gNB to communicate the uplink PDCP SN receiver state and downlink PDCP SN transmitter state of the DRB to which PDCP state preservation applies (i.e., for RLC-AM). The uplink PDCP SN receiver state includes at least the PDCP SN of the first missing UL PDCP SDU and may include a bitmap (if any) of the received states of the out-of-order UL PDCP SDUs, which the terminal device 120 needs to retransmit in the target cell (associated with the target gNB). The downlink PDCP SN transmitter state indicates the next PDCP SN that the target gNB should assign to a new PDCP SDU that does not yet have a PDCP SN.

[0172] In U-plane processing for handover, for RLC-AM bearers, in the case of sequential delivery and application replication, the PDCP SN is maintained per DRB base, and the source gNB notifies the target gNB about the next DL PDCP SN to assign to packets (from the source gNB or UPF) that do not yet have a PDCP sequence number. For security synchronization, the HFN is also maintained, and the source gNB provides the target gNB with one reference HFN for UL and one reference HFN for DL, i.e., the HFN and the corresponding SN. The source gNB notifies the target gNB of at least one of the following: PDU Set SN, Start indication, End indication, or PDU set size. Specifically, the PDCP Set SN is maintained, and the source gNB notifies the target gNB about the next PDU Set SN to assign to packets (from the source gNB or UPF) that do not yet have a PDU Set SN. The source gNB may also notify the target gNB of the "start instruction" / "end instruction" and / or the size of the PDU set. If necessary, the importance level (or priority, or PDU set type) or "correlated PDU set SN" should also be notified from the source gNB to the target gNB. Furthermore, in the case of an RLC-UM bearer, the PDU set SN, PDCP SN, and HFN are reset in the target gNB unless a DAPS handover is configured on the bearer.

[0173] In some exemplary embodiments, during a DAPS handover, both downlink and uplink operations are performed at the PDU set granularity.

[0174] In one example, regarding downlink processing, the source gNB is responsible for assigning the downlink PDCP SN / PDU set SN until the SN assignment is handed over to the target gNB 110-2 and data transfer occurs. That is, the source gNB does not stop assigning PDCP SN / PDU set SNs to downlink packets until it receives a HANDOVER SUCCESS message and sends an SN STATUS TRANSFER message to the target gNB. When the source gNB assigns the downlink PDCP SN / PDU set SN, it begins scheduling downlink data on the source radio link and begins transferring the downlink PDCP SDU to the target gNB along with the assigned PDCP SN / PDU set SN. For security synchronization, the HFN is maintained for the transferred downlink SDU with the PDCP SN assigned by the source gNB. The source gNB sends an EARLY STATUS TRANSFER message to communicate the DL COUNT value indicating the PDCP SN and HFN of the first PDCP SDU that the source gNB is transferring to the target gNB. After the SN allocation is handed over to the target gNB, the PDU set SN, HFN, and PDCP SN are maintained. The SN STATUS TRANSFER message also indicates the next DL PDCP SN / PDU set SN to be assigned to packets that do not yet have a PDCP sequence number / PDU set SN, for RLC-UM as well. The "start instruction" / "end instruction" and / or PDU set size may also be handed over to the target gNB. If necessary, the importance level (or priority, or PDU set type) or "correlated PDU set SN" should be communicated from the source gNB to the target gNB.

[0175] In another example, regarding uplink processing, during the handover execution period, the UE maintains separate security contexts and ROHC header compressor contexts for uplink transmissions to the source gNB and target gNB. The UE maintains a common UL PDCP SN / PDU set SN assignment. PDCP SN / PDU set SN continuity is supported for both RLC-AM and UM DRBs where DAPS is configured. PDU set SN, HFN, and PDCP SN are maintained within the target gNB. The SN STATUS TRANSFER message also indicates the PDU set SN and COUNT of the first missing PDCP SDU that the target should begin delivering to the 5GC, for RLC-UM as well.

[0176] Thus, packet processing at the PDU set granularity is supported, as is PDU set-based processing. Therefore, XR / media service processing can be performed at the PDU set granularity rather than the PDU granularity. At the same time, the processing of each data packet in the QoS flow is no longer relatively independent. However, PDU sets that depend on other PDU sets can be processed (e.g., dropped / discarded) based on those other PDU sets. As a result, communication quality and network performance are improved.

[0177] Figure 5 is a flowchart of an exemplary method 500 implemented in a terminal device according to some embodiments of the present disclosure. For illustrative purposes, the method 500 will be described with reference to Figure 1 from the perspective of the terminal device 120.

[0178] In block 510, the terminal device 120 receives from the network device 120 at least one of the following parameters associated with the PDU set: a first parameter indicating whether all PDUs in the PDU set are required by the application layer; a second parameter indicating whether the PDU set is discarded if an additional PDU set associated with the PDU set is lost or discarded; a third parameter indicating a discard timer for the PDU set; or a fourth parameter indicating a sorting timer for the PDU set. In block 520, the terminal device 120 processes the PDU set based on at least one of the received parameters.

[0179] In some exemplary embodiments, the header of a PDCP data PDU includes at least one of the following fields: a first field indicating the SN of the PDU set to which the PDCP data PDU belongs; a second field indicating whether the PDCP data PDU is the first PDU of the PDU set to which it belongs; or a third field indicating whether the PDCP data PDU is the last PDU of the PDU set to which it belongs.

[0180] In some exemplary embodiments, the header of the PDCP data PDU further defines at least one of the following fields: a fourth field indicating the SN of another PDU set, wherein the PDU set to which the PDCP data PDU belongs is associated with the PDU set identified by that field; a fifth field indicating whether the fourth field is present in the header of the PDCP data PDU; or a sixth field indicating the importance or priority of the PDU set.

[0181] In some exemplary embodiments, the terminal device further determines the range of counts or PDCP SNs belonging to a PDU set from a first count or first PDCP SN, which is a count or PDCP SN of a PDCP data PDU with the second field set to 1, to a second count or second PDCP SN, which is a count or PDCP SN of a PDCP data PDU with the third field set to 1, and determines whether the PDCP set has lost at least one PDU based on the information regarding the PDU set SN, the count or PDCP SN, the second field and the third field.

[0182] In some exemplary embodiments, each of the second and third fields uses one bit in the PDCP header.

[0183] In some exemplary embodiments, the fifth field uses one bit in the PDCP header. Depending on whether the fifth field indicates that the fourth field is present in the PDCP header, the fourth field is newly added to the PDCP header.

[0184] In some exemplary embodiments, the sixth field uses at least one bit in the PDCP header.

[0185] In some exemplary embodiments, packets from higher layers are organized at the PDCP layer into PDU set units, and PDU set information is transmitted within the band in the PDCP header of each PDU in the PDU set.

[0186] In some exemplary embodiments, the terminal device 120 further maintains a common PDU set SN allocation during the handover execution period, and the continuity of the PDU set SN is supported for both RLC-AM and UM DRBs in which DAPS is configured.

[0187] In some exemplary embodiments, the terminal device 120, upon first receiving a PDCP SDU belonging to a PDU set from a higher layer, activates the discard timer associated with the PDU set, and, when the discard timer for the SDU set expires, discards the PDU and / or SDU belonging to the corresponding PDU set, and / or the PDU and / or SDU of other PDU sets associated with that PDU set, wherein PDUs within the same PDU set share the same discard timer.

[0188] In some exemplary embodiments, the terminal device 120, upon first receiving a PDU belonging to a PDU set from a lower layer, activates the sorting timer associated with that PDU set, and, when the sorting timer for that SDU set expires, discards the PDUs and / or SDUs belonging to the corresponding PDU set, and / or the PDUs and / or SDUs of other PDU sets associated with that PDU set, so that PDUs within the same PDU set share the same sorting timer.

[0189] In some exemplary embodiments, the terminal device 120 further performs the action of stopping and resetting the sorting timer while it is running, if requested by a higher layer to pause the transmission of PDU sets.

[0190] In some exemplary embodiments, the terminal device 120 further stops and restarts the sort timer while it is running, if the sort timer's value has been set by a higher layer.

[0191] In some exemplary embodiments, the terminal device 120 further performs the following actions when the discard timer for a PDCP SDU expires: discard the PDU and / or SDU belonging to the corresponding PDU set, and / or the PDU and / or SDU of other PDU sets associated with the said PDU set.

[0192] In some exemplary embodiments, the terminal device 120 further discards the PDU and / or SDU belonging to the corresponding PDU set, and / or PDU / SDUs of other PDU sets associated with that PDU set, when the sorting timer for the PDCP SDU expires, depending on whether all PDUs in the PDU set are required by the application layer and at least one PDU and / or SDU of the PDCP set is set to be lost.

[0193] Thus, packet processing at the PDU set granularity is supported, as is PDU set-based processing. Therefore, XR / media service processing can be performed at the PDU set granularity rather than the PDU granularity. At the same time, the processing of each data packet in the QoS flow is no longer relatively independent. However, PDU sets that depend on other PDU sets can be processed (e.g., dropped / discarded) based on those other PDU sets. As a result, communication quality and network performance are improved.

[0194] Figure 6 is a flowchart of an exemplary method 600 implemented in a network device according to some embodiments of the present disclosure. For discussion purposes, method 600 will be described with reference to Figures 1 and 5 from the perspective of network device 110.

[0195] In block 610, the network device 110 determines at least one of the following parameters associated with the PDU set: a first parameter indicating whether all PDUs in the PDU set are required by the application layer; a second parameter indicating whether the PDU set is discarded if an additional PDU set associated with the PDU set is lost or discarded; a third parameter indicating a discard timer for the PDU set; or a fourth parameter indicating a sorting timer for the PDU set. In block 620, the network device 110 transmits at least one of these parameters to the terminal device 120.

[0196] In some exemplary embodiments, the header of a PDCP data PDU includes at least one of the following fields: a first field indicating the SN of the PDU set to which the PDCP data PDU belongs; a second field indicating whether the PDCP data PDU is the first PDU of the PDU set to which it belongs; or a third field indicating whether the PDCP data PDU is the last PDU of the PDU set to which it belongs.

[0197] In some exemplary embodiments, the header of the PDCP data PDU further defines at least one of the following fields: a fourth field indicating the SN of another PDU set, wherein the PDU set to which the PDCP data PDU belongs is associated with the PDU set identified by this field; a fifth field indicating whether the fourth field is present in the header of the PDCP data PDU; or a sixth field indicating the importance or priority of the PDU set.

[0198] In some exemplary embodiments, the network device is the original source network device 110-1 to which the terminal device 120 is handed over to the target network device 110-2.

[0199] In some exemplary embodiments, source network device 110-1 sends a message for a handover request to target network device 110-2, which provides information to prepare for a handover to the target network device. This information includes at least PDU set-related information, which includes information about at least a first parameter and a second parameter.

[0200] In some exemplary embodiments, the source network device 110-1 further performs the following for the RLC-AM bearer: maintaining the PDU set SN and transmitting to the target network device 110-2 the next PDU set SN to be assigned to packets that do not have a PDU set SN.

[0201] In some exemplary embodiments, the source network device 110-1 further transmits to the target network device 110-2 information relating to at least one of a first field, a second field, a third field, or the size of a PDU set.

[0202] In some exemplary embodiments, the source network device 110-1 further transmits to the target network device 110-2 information regarding the importance level or priority, or the associated PDU set.

[0203] In some exemplary embodiments, if DAPS is set on the DRB, the source network device 110-1 further performs the action of sending a message to the target network device 110-2 for early state transfer, and the values ​​of the PDU set SN and / or downlink count transmitted in the message indicate the PDU set SN, PDCP SN and HFN of a first PDCP SDU that the source network device 110-1 transfers to the target network device 110-2.

[0204] In some exemplary embodiments, the source network device 110-1 further performs the task of assigning the SN and / or PDU set SN to the downlink PDCP SDU until it sends a message for SN state transfer to the target network device 110-2.

[0205] In some exemplary embodiments, the message for SN state transfer indicates to the target network device 110-2 the PDU set SN and count of a first missing PDCP SDU that the target network device 110-2 should initiate delivery of.

[0206] In some exemplary embodiments, source network device 110-1 further performs the following: assigning a downlink PDCP SN and / or PDU set SN until the SN assignment is handed over to target network device 110-2; scheduling downlink data on the source radio link and initiating the transfer of the downlink PDCP SDU along with the assigned PDCP SN and / or PDU set SN to target network device 110-2 when source network device 110-1 assigns the downlink PDCP SN and / or PDU set SN; and maintaining the PDU set SN, HFN, and PDCP SN after the SN assignment has been handed over to target network device 110-2.

[0207] In some exemplary embodiments, the source network device 110-1 further transmits to the target network device 110-2 information relating to at least one of a first field, a second field, a third field, or the size of a PDU set.

[0208] In some exemplary embodiments, the source network device 110-1 further transmits to the target network device 110-2 information regarding the importance level or priority, or the associated PDU set.

[0209] In some exemplary embodiments, the source network device 110-1 further transmits a message for a handover request to the target network device 110-2, which includes PDU set-related information including information about at least a first parameter and a second parameter, and transmits a message for SN state transfer to the target network device.

[0210] In some exemplary embodiments, source network device 110-1 further performs the following: requesting a DAPS handover for one or more DRBs; and for DRBs on which DAPS is configured, sending a message to target network device 110-2 for early state transfer, the message including the values ​​of PDU set SN and / or downlink count indicating the PDU set SN, PDCP SN and HFN of a first PDCP SDU that source network device 110-1 transfers to target network device 110-2.

[0211] In some exemplary embodiments, the source network device 110-1 further performs the action of sending a message for SN status transfer to the target network device 110-2 for DRBs where DAPS is not configured.

[0212] In some exemplary embodiments, the network device is the target network device 110-2 to which the terminal device 120 is handed over from the source network device 110-1.

[0213] In some exemplary embodiments, the target network device 110-2 further receives a message from the source network device 110-1 for a handover request, which provides information for preparing the handover at the target network device. This information includes at least PDU set-related information, which includes information about at least a first parameter and a second parameter.

[0214] In some exemplary embodiments, when the target network device 110-2 determines that a DAPS handover is configured for the RLC-UM bearer, it further performs the following actions for the RLC-UM bearer: resetting the PDU set SN, PDCP SN, and HFN.

[0215] Thus, packet processing at the PDU set granularity is supported, as is PDU set-based processing. Therefore, XR / media service processing can be performed at the PDU set granularity rather than the PDU granularity. At the same time, the processing of each data packet in the QoS flow is no longer relatively independent. However, PDU sets that depend on other PDU sets can be processed (e.g., dropped / discarded) based on those other PDU sets. As a result, communication quality and network performance are improved.

[0216] Figure 7 is a schematic block diagram of a device 700 suitable for implementing an embodiment of the present disclosure. The device 700 may be considered as another exemplary embodiment of the terminal device 120 and / or network device 110 as shown in Figure 1. Thus, the device 700 may be implemented in or as part of the terminal device 120 or the network device 110.

[0217] As illustrated, the device 700 comprises a processor 710, a memory 720 coupled to the processor 710, appropriate transmitters (TX) and receivers (RX) 740 coupled to the processor 710, and a communication interface coupled to the TX / RX 740. The memory 710 stores at least a portion of the program 730. The TX / RX 740 is used for bidirectional communication. The TX / RX 740 has at least one antenna to facilitate communication, although the access node referred to in this disclosure may actually have multiple antennas. The communication interface may represent any interface necessary for communication with other network elements, such as an X2 interface for bidirectional communication between eNBs, an S1 interface for communication between a Mobility Management Entity (MME) / Serving Gateway (S-GW) and an eNB, an Un interface for communication between an eNB and a Relay Node (RN), or a Uu interface for communication between an eNB and a terminal device.

[0218] It is assumed that program 730 includes program instructions that, when executed by the associated processor 710, enable the device 700 to operate according to embodiments of the present disclosure, as described herein with reference to Figures 2 to 6. Embodiments of the present disclosure may be implemented by computer software executable by the processor 710 of the device 700, by hardware, or by a combination of software and hardware. The processor 710 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 710 and memory 720 may form processing means 750 suitable for implementing various embodiments of the present disclosure.

[0219] Memory 720 may be of any type suitable for a local technology network and may be implemented using any suitable data storage technology, such as non-temporary computer-readable storage media, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. Although only one memory 720 is shown in device 700, there may be several physically different memory modules in device 700. Processor 710 may be of any type suitable for a local technology network and may include, as non-limiting examples, one or more of general-purpose computers, dedicated computers, microprocessors, digital signal processors (DSPs), and processors based on multicore processor architectures. Device 700 may have multiple processors, for example, application-specific integrated circuit chips that are time-dependent to a clock that synchronizes the main processor.

[0220] In short, embodiments of this disclosure can provide the following solutions.

[0221] This disclosure provides a method of communication, the method comprising: a terminal device receiving from a network device at least one of the following parameters associated with a set of protocol data units (PDUs): a first parameter indicating whether all PDUs in the PDU set are required by the application layer; a second parameter indicating whether the PDU set is discarded if an additional set of PDUs associated with the PDU set is lost or discarded; a third parameter indicating a discard timer for the PDU set; or a fourth parameter indicating a sorting timer for the PDU set; and processing the PDU set based on the at least one of the received parameters.

[0222] In one embodiment, the method defines at least one field in the header of a Packet Data Convergence Protocol (PDCP) data PDU: a first field indicating the serial number (SN) of the PDU set to which the PDCP data PDU belongs; a second field indicating whether the PDCP data PDU is the first PDU of the PDU set to which it belongs; or a third field indicating whether the PDCP data PDU is the last PDU of the PDU set to which it belongs.

[0223] In one embodiment, the method further defines at least one of the following fields in the header of the PDCP data PDU: a fourth field indicating the SN of another PDU set, wherein the PDU set to which the PDCP data PDU belongs is associated with the PDU set identified by the fourth field; a fifth field indicating whether the fourth field is present in the header of the PDCP data PDU; or a sixth field indicating the importance or priority of the PDU set.

[0224] In one embodiment, the method further includes determining the range of counts or PDCP SNs belonging to a PDU set from a first count or first PDCP SN which is a count or PDCP SN of a PDCP data PDU with a second field set to 1, to a second count or second PDCP SN which is a count or PDCP SN of a PDCP data PDU with a third field set to 1, and determining whether the PDCP set has lost at least one PDU based on information relating to the PDU set SN, the count or PDCP SN, the second field, and the third field.

[0225] In one embodiment, the method uses one bit in the PDCP header for each of the second and third fields.

[0226] In one embodiment, the method uses one bit in the PDCP header for the fifth field, and the fourth field is newly added to the PDCP header in accordance with the fifth field indicating that the fourth field is present in the PDCP header.

[0227] In one embodiment, the method uses at least one bit in the PDCP header for the sixth field.

[0228] In one embodiment, the method involves the following: packets from higher layers are organized in PDU set units at the PDCP layer, and PDU set information is transmitted within the band of the PDCP header of each PDU in the PDU set.

[0229] In one embodiment, the method further includes maintaining a common PDU set SN allocation in the terminal device during the handover execution period, wherein the continuity of the PDU set SN is supported for both RLC-AM and UM DRB on which DAPS is configured.

[0230] In one embodiment, the method further includes activating a discard timer associated with a PDU set upon the first reception of a PDCP SDU belonging to the PDU set from a higher layer, and discarding the PDU and / or SDU belonging to the corresponding PDU set, and / or the PDU and / or SDU of other PDU sets associated with the PDU set, when the discard timer for the SDU set has expired, wherein PDUs within the same PDU set share the same discard timer.

[0231] In one embodiment, the method further includes activating a sorting timer associated with a PDU set upon the first reception of a PDU belonging to the PDU set from a lower layer, and discarding the PDU and / or SDU belonging to the corresponding PDU set, and / or the PDU and / or SDU of other PDU sets associated with the PDU set, when the sorting timer for the SDU set has expired, wherein PDUs within the same PDU set share the same sorting timer.

[0232] In one embodiment, the method further includes stopping and resetting the sorting timer while it is running if a higher layer requests that the transmission of the PDU set be paused.

[0233] In one embodiment, the method further includes stopping and restarting the sorting timer while it is running, if the value of the sorting timer is set by a higher layer.

[0234] In one embodiment, the method further includes discarding the PDU and / or SDU belonging to the corresponding PDU set, and / or the PDU and / or SDU of other PDU sets associated with the PDU set, when the discard timer for the PDCP SDU has expired.

[0235] In one embodiment, the method further includes discarding the PDU and / or SDU belonging to the corresponding PDU set, and / or PDU / SDU of other PDU sets associated with the PDU set, when the sorting timer expires for a PDCP SDU, depending on whether all PDUs in a PDU set are required by the application layer and at least one PDU and / or SDU of a PDCP set is configured to be lost.

[0236] This disclosure provides a method of communication, the method comprising: determining, in a network device, at least one of the following parameters associated with a set of protocol data units (PDUs): a first parameter indicating whether all PDUs in the PDU set are required by the application layer; a second parameter indicating whether the PDU set is discarded if an additional set of PDUs associated with the PDU set is lost or discarded; a third parameter indicating a discard timer for the PDU set; or a fourth parameter indicating a sorting timer for the PDU set; and transmitting at least one of the parameters to a terminal device.

[0237] In one embodiment, the method defines at least one of the following fields in the header of the PDCP data PDU: a first field indicating the serial number (SN) of the PDU set to which the PDCP data PDU belongs; a second field indicating whether the PDCP data PDU is the first PDU of the PDU set to which it belongs; or a third field indicating whether the PDCP data PDU is the last PDU of the PDU set to which it belongs.

[0238] In one embodiment, the method further defines at least one field in the header of the PDCP data PDU, which is a fourth field indicating the SN of another PDU set, wherein the PDU set to which the PDCP data PDU belongs is associated with the PDU set identified by this field; a fifth field indicating whether or not the fourth field is present in the header of the PDCP data PDU; or a sixth field indicating the importance or priority of the PDU set.

[0239] In one embodiment, the method is such that the network device is the original source network device from which the terminal device is handed over to the target network device.

[0240] In one embodiment, the method further includes sending a message for a handover request to the target network device, which provides information for preparing for a handover to the target network device, wherein the information includes at least PDU set-related information, and the PDU set-related information includes information about at least the first parameter and the second parameter.

[0241] In one embodiment, the method further includes maintaining a PDU set serial number (SN) for the RLC-AM bearer and transmitting to the target network device the next PDU set SN to be assigned to packets that do not have a PDU set SN.

[0242] In one embodiment, the method further includes transmitting to the target network device information relating to at least one of the first field, the second field, the third field, or the size of the PDU set.

[0243] In one embodiment, the method further includes transmitting information to the target network device regarding the importance level or priority, or the associated PDU set.

[0244] In one embodiment, the method further includes, if DAPS is configured on the DRB, sending a message for early state transfer to the target network device, wherein the values ​​of the PDU set SN and / or downlink count transmitted in the message indicate the PDU set SN, PDCP SN and HFN of a first PDCP SDU that the source network device transfers to the target network device.

[0245] In one embodiment, the method further includes allocating the SN and / or PDU set SN to the downlink PDCP SDU until a message for SN state transfer is sent to the target network device.

[0246] In one embodiment, the method provides the target network device with the PDU set SN and count of a first missing PDCP SDU that the target network device should begin distributing.

[0247] In one embodiment, the method further includes assigning a downlink PDCP SN and / or PDU set SN until the SN allocation is handed over to the target network device; scheduling downlink data on the source radio link and initiating the transfer of the downlink PDCP SDU along with the assigned PDCP SN and / or PDU set SN to the target network device when the source network device assigns the downlink PDCP SN and / or PDU set SN; and maintaining the PDU set SN, HFN, and PDCP SN after the SN allocation has been handed over to the target network device.

[0248] In one embodiment, the method further includes transmitting to the target network device information relating to at least one of the first field, the second field, the third field, or the size of the PDU set.

[0249] In one embodiment, the method further includes transmitting information to the target network device regarding the importance level or priority, or the associated PDU set.

[0250] In one embodiment, the method further includes sending a message for a handover request to the target network device, which includes protocol data unit (PDU) set-related information including information about at least the first and second parameters, and sending a message for SN state transfer to the target network device.

[0251] In one embodiment, the method further includes requesting a DAPS handover for one or more DRBs and sending a message for early state transfer to the target network device for the DRBs on which DAPS is configured, the message including a value for PDU set SN and / or downlink count indicating the PDU set SN, PDCP SN and HFN of a first PDCP SDU that the source network device transfers to the target network device.

[0252] In one embodiment, the method further includes sending a message for SN status transfer to the target network device for DRBs in which DAPS is not configured.

[0253] In one embodiment, the method described above involves a network device which is the target network device to which a terminal device is handed over from a source network device.

[0254] In one embodiment, the method further includes receiving a message from the source network device for a handover request, which provides information for preparing the handover at the target network device, wherein the information includes at least PDU set-related information, and the PDU set-related information includes at least information relating to the first parameter and the second parameter.

[0255] In one embodiment, the method further includes, when it is determined that a DAPS handover is set on the RLC-UM bearer, resetting the PDU set SN, PDCP SN, and HFN for the RLC-UM bearer.

[0256] This disclosure provides a terminal device comprising a processor and a memory storing computer program code, wherein the memory and the computer program code are configured together with the processor to cause the terminal device to execute the above method implemented in the terminal device 120.

[0257] This disclosure provides a network device comprising a processor and a memory storing computer program code, wherein the memory and the computer program code, together with the processor, are configured to cause the network device to execute the above method implemented in the network device 110.

[0258] This disclosure provides a computer-readable medium that, when executed by the processor of the device, stores instructions causing the device to perform the above-mentioned method implemented in the terminal device 120 or the network device 110.

[0259] Overall, various embodiments of the Disclosure may be implemented in hardware or dedicated circuitry, software, logic, or any combination thereof. Some embodiments may be implemented in hardware, while others may be implemented in firmware or software that can be executed by a controller, microprocessor, or other computing device. Although various embodiments of the Disclosure are illustrated and described using block diagrams, flowcharts, or any other pictorial representation, it should be understood that any blocks, devices, systems, techniques, or methods described herein may be implemented, in non-limiting examples, in hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or controllers or other computing devices, or any combination thereof.

[0260] This disclosure also provides at least one computer program product tangibly stored on a non-temporary computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions contained in a program module, which are executed within a device on a real or virtual processor of interest to perform the processes or methods described above with reference to Figures 5-6. Generally, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc., that perform a specific task or realize a specific abstract data type. In various embodiments, the functions of program modules may be combined or separated among program modules as needed. The machine-executable instructions of a program module may be executed within a local or distributed device. In a distributed device, program modules may reside in both local and remote storage media.

[0261] Program code for performing the methods of this disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a dedicated computer, or other programmable data processing device, and when executed by the processor or controller, the program code may implement the functions / operations specified in the flowcharts and / or block diagrams. The program code may run entirely on a machine, partially on a machine, as an independent software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0262] The program code described above may be implemented on a machine-readable medium, which may be any tangible medium that can contain or store programs used by or associated with an instruction execution system, device, or apparatus. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or apparatus, or any suitable combination of the aforementioned mediums. More specific examples of machine-readable storage media may include electrical connections with one or more wires, portable computer diskettes, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the above.

[0263] While the operations have been described in a specific order, it should not be understood that, in order to obtain the desired results, these operations must be performed in the specific order or sequence indicated, or that all described operations must be performed. In some cases, multitasking and parallel processing may be advantageous. Similarly, while some specific implementation details are included in the above discussion, these should not be interpreted as limitations on the scope of this disclosure, but rather as descriptions of features that may be specific to a particular embodiment. Some features described in the context of individual embodiments may be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may be implemented separately or in any suitable subcombination in multiple embodiments.

[0264] While this disclosure has been described in language specific to structural features and / or methodological behavior, it should be understood that the disclosure as defined in the attached claims is not necessarily limited to the specific features or behaviors described above. Rather, the specific features and behaviors described above are disclosed as exemplary forms of implementing the claims.

Claims

1. A target network device, Means for receiving a handover request message from a source network device, the handover request message for preparing a handover, the handover request message including first information indicating whether all protocol data units (PDUs) are required in a PDU set, and second information indicating whether the terminal device will perform at least one discard operation on the PDU set. Means for transmitting the second information to a terminal device, Equipped with, Target network device.

2. The device further comprises means for transmitting a fourth piece of information indicating a discard timer to the terminal device, Based on the expiration of the discard timer, the terminal device discards at least one of the PDUs belonging to the PDU set and a Service Data Unit (SDU). The target network device according to claim 1.

3. The system further includes means for receiving third information from a source network device, wherein the third information is PDU set sequence number and The PDU set completion message and The size of the PDU set, The importance level of the PDU set, Including at least one of the following: The target network device according to claim 1.

4. The first piece of information mentioned above is part of the Quality of Service (QoS) profile. The target network device according to claim 1.

5. A terminal device, A means for receiving a Radio Resource Control (RRC) message from a target network device that has received a handover request message from a source network device, which includes first information indicating whether all PDUs in a set of Protocol Data Units (PDUs) are required in the PDU set, and second information indicating that the terminal device will perform at least one discard operation to discard all PDUs included in the PDU set, A decision means that determines to perform the disposal operation based on the second information, Equipped with, Terminal device.

6. The Radio Resource Control (RRC) message includes third information indicating a discard timer, At least one of the aforementioned PDUs and all of the Service Data Units (SDUs) is discarded upon the expiration of the discard timer. The terminal device according to claim 5.

7. The target network device further includes means for receiving a fourth piece of information from the source network device. The information in the previous 4 is, PDU set sequence number and The PDU set completion message and The size of the PDU set, The importance level of the PDU set, Including at least one of the following: The terminal device according to claim 5.

8. The first piece of information mentioned above is part of the Quality of Service (QoS) profile. The terminal device according to claim 5.

9. A method in a target network device, Receiving a handover request message from a source network device, which includes a handover request message for preparing a handover, the handover request message containing first information indicating whether all protocol data units (PDUs) are required in a PDU set, and second information indicating whether the terminal device will perform at least one discard operation on the PDU set. Transmitting the aforementioned second information to the terminal device, Equipped with, method.

10. Further comprising transmitting a fourth piece of information indicating a discard timer to the terminal device, Based on the expiration of the discard timer, the terminal device discards at least one of all PDUs belonging to the PDU set and all Service Data Units (SDUs). The method according to claim 9.

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