First or second or third node and method performed by same

Abstract

The present disclosure provides a method executed by a second node in a communication system, the method comprising: sending a first message to a third node, the first message comprising first indication information, the first indication information being used for indicating whether the second node supports packet data unit (PDU) set processing of an augmented reality (XR) service; and receiving a second message from the third node, the second message including XR service configuration information if the first indication information indicates that the second node supports PDU set processing of the XR service.

Description

Technical Field

[0001] The present disclosure relates to the field of communications, and more particularly, to a first or second or third node and a method executed thereby. Background Art

[0002] In order to meet the increased demand for wireless data communication services since the deployment of 4G communication systems, efforts have been made to develop improved 5G or quasi-5G communication systems. Therefore, 5G or quasi-5G communication systems are also referred to as "super 4G networks" or "post-LTE systems."

[0003] Wireless communication is one of the most successful innovations in modern history. The number of subscribers to wireless communication services recently exceeded 5 billion and continues to grow rapidly. The demand for wireless data services is growing rapidly due to the increasing popularity of smartphones and other mobile data devices (e.g., tablets, laptops, netbooks, e-book readers, and machine-type devices) among consumers and enterprises. In order to meet the high growth of mobile data services and support new applications and deployments, it is critical to improve the efficiency and coverage of the wireless interface. Summary of the invention

[0004] According to one aspect of the present disclosure, a method performed by a second node in a communication system is provided, the method comprising: sending a first message to a third node, the first message comprising first indication information, the first indication information being used to indicate whether the second node supports packet data unit (PDU) set processing of an extended reality (XR) service; and receiving a second message from the third node, wherein if the first indication information indicates that the second node supports PDU set processing of the XR service, the second message comprises XR service configuration information.

[0005] According to the method provided by the present disclosure and executed by the second node in the communication system, the method also includes: receiving a third message from the first node, the third message including or not including XR service configuration information corresponding to the first node; sending a fourth message to the first node, the fourth message including second indication information, and the second indication information is used to indicate whether the second node supports PDU set processing of extended reality XR service.

[0006] According to the method provided by the present disclosure, which is performed by the second node in the communication system, the second node is the destination base station, the third node is the session management function SMF, or the access and mobility management function AMF, and the first node is the source base station.

[0007] According to the method provided by the present disclosure and executed by the second node in the communication system, the method also includes: sending a fifth message to the user plane of the second node, the fifth message including or not including XR service configuration information corresponding to the second node; receiving a sixth message from the user plane of the second node, the sixth message including third indication information, and the third indication information is used to indicate whether the user plane of the second node supports PDU set processing of the XR service.

[0008] According to the method provided by the present disclosure and executed by the second node in the communication system, the XR service configuration information includes at least one of the following: the period of XR data transmitted on the quality of service QoS flow, the data burst arrival time, the data survival time, and the jitter configuration information; the QoS flow identifier, the type of PDU set, the identifier of the PDU set, the PDU set delay budget PSDB, which is used to indicate the upper limit of the delay that the PDU set may experience at the user plane function UPF for the transmission between the user equipment UE and the N6 termination point, the PDU set error rate PDER, which is used to indicate the upper limit of the non-congestion related PDU set loss rate, and the PDU set integrated processing indication PSIHI, which is used to indicate whether the application layer needs all PDUs in the PDU set when using the PDU set.

[0009] According to one aspect of the present disclosure, a method performed by a third node in a communication system is provided, the method comprising: receiving a first message from a second node, the first message comprising first indication information, the first indication information being used to indicate whether the second node supports packet data unit (PDU) set processing of an extended reality (XR) service; and sending a second message to the second node, wherein if the first indication information indicates that the second node supports PDU set processing of the XR service, the second message comprises XR service configuration information.

[0010] According to one aspect of the present disclosure, a method performed by a first node in a communication system is provided, the method comprising: sending a third message to a second node, the third message including or not including extended reality XR service configuration information corresponding to the first node; receiving a fourth message from the second node, the fourth message including second indication information, and the second indication information is used to indicate whether the second node supports packet data unit PDU set processing of the extended reality XR service.

[0011] According to the method provided by the present disclosure and executed by the first node in the communication system, the method also includes: sending a seventh message to the user plane of the first node, the seventh message including fourth indication information, and the fourth indication information is used to indicate whether the second node supports PDU set processing of the XR service.

[0012] According to the method provided by the present disclosure and executed by the first node in the communication system, the method further includes: sending a radio resource control protocol RRC reconfiguration request message to a user equipment, the RRC reconfiguration request message including fifth indication information, and the fifth indication information is used to indicate whether the second node supports PDU set processing of the XR service; wherein the destination cell of the user equipment is selected based on the fifth indication information.

[0013] According to one aspect of the present disclosure, a method performed by a second node in a communication system is provided, the method comprising: receiving an eighth message from a first node, the eighth message comprising a sequence number PSSN of a packet data unit PDU set; and performing corresponding operations based on the eighth message.

[0014] According to the method provided by the present disclosure, the method is performed by a second node in a communication system, wherein the first node is one of the following: a base station, a source base station, a user plane gNB-CU-UP of a centralized unit of a source base station, a control plane gNB-CU-CP of a centralized unit of a source base station, an access and mobility management function AMF, a session management function SMF, or a user plane function UPF; and / or the second node is one of the following: a base station, a destination base station, a destination gNB-CU-UP, a source gNB-CU-CP, a destination gNB-CU-CP, an AMF, an SMF, or an UPF.

[0015] According to the method performed by the second node in the communication system provided by the present disclosure, the eighth message also includes sixth indication information, and the sixth indication information is used to indicate that the PDU in the PDU set corresponding to the PSSN is lost or to indicate that the PDU in the PDU set is discarded.

[0016] According to the method performed by the second node in the communication system provided by the present disclosure, the eighth message is a control plane message or a user plane message.

[0017] According to the method provided by the present disclosure and executed by the second node in the communication system, the method further includes: receiving a data packet from a third node, and performing the corresponding operation includes: discarding the PDU in the PDU set corresponding to the PSSN; wherein the third node is the UPF.

[0018] According to the method provided by the present disclosure and executed by the second node in the communication system, the executing corresponding operation includes: sending a ninth message to the fourth node, the ninth message including the PSSN and / or the seventh indication information, the seventh indication information is used to indicate that the PDU in the PDU set corresponding to the PSSN is lost or indicates that the PDU in the PDU set is discarded; wherein the fourth node is one of the following: a base station, a destination base station, a destination gNB-CU-UP, a gNB-CU-CP, a destination gNB-CU-CP, an AMF, an SMF, or an UPF.

[0019] According to the method provided by the present disclosure and executed by the second node in the communication system, the executing corresponding operation includes: not sending all PDUs in the PDU set corresponding to the PSSN to the gNB-CU-UP, wherein the gNB-CU-UP is one of the following: the target gNB-CU-UP, the source gNB-CU-UP, and the gNB-CU-UP of the current serving user equipment UE.

[0020] According to the method provided by the present disclosure and executed by the second node in the communication system, the executing corresponding operation includes: sending a PDU belonging to a new PDU set to a fifth node, the new PDU set is the next PDU set of the PDU set corresponding to the PSSN; wherein the fifth node is one of the following: a destination base station, a destination gNB-CU-UP, or a gNB-CU-UP currently serving a UE.

[0021] According to another aspect of the present disclosure, a first node is provided, comprising: a transceiver configured to send and receive signals to and from the outside; and a controller configured to control the transceiver to execute the method executed by the first node.

[0022] According to another aspect of the present disclosure, a second node is provided, wherein the first node includes: a transceiver configured to send and receive signals to and from the outside; and a controller configured to control the transceiver to execute the method executed by the second node.

[0023] According to another aspect of the present disclosure, a third node is provided, wherein the first node includes: a transceiver configured to send and receive signals to the outside; and a controller configured to control the transceiver to execute the method executed by the third node.

[0024] According to another aspect of the present disclosure, a non-transitory computer-readable recording medium is provided, on which a program for executing any of the above methods when executed by a computer is stored. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1is an exemplary system architecture for System Architecture Evolution (SAE).

[0026] Figure 2 is an exemplary system architecture according to various embodiments of the present disclosure.

[0027] Figure 3 is an exemplary architecture of a base station according to various embodiments of the present disclosure.

[0028] Figure 4 It is a schematic diagram for describing a process in which a user equipment UE moves from a first node to a second node according to various embodiments of the present disclosure.

[0029] Figure 5 is a schematic diagram for describing another process in which a user equipment UE moves from a first node to a second node according to various embodiments of the present disclosure.

[0030] Figure 6 is a schematic diagram for describing another process in which a user equipment UE moves from a first node to a second node according to various embodiments of the present disclosure.

[0031] Figure 7 is a schematic diagram for describing yet another process in which a user equipment UE moves from a first node to a second node according to various embodiments of the present disclosure.

[0032] Figure 8 is a schematic diagram for describing an Xn-based process in which a user equipment UE moves from a first node to a second node according to various embodiments of the present disclosure.

[0033] Fig. 9 is a schematic diagram for describing another process based on Xn in which a user equipment UE moves from a first node to a second node according to various embodiments of the present disclosure.

[0034] Fig.10 is a schematic diagram for describing an NG-based process in which a user equipment UE moves from a first node to a second node according to various embodiments of the present disclosure.

[0035] Fig.11 is a schematic diagram for describing another NG-based process in which a user equipment UE moves from a first node to a second node according to various embodiments of the present disclosure.

[0036] Fig.12 It is a schematic diagram for describing a first node sending a message to a second node for controlling data transmission according to various embodiments of the present disclosure.

[0037] Fig.13 is a block diagram of a network node according to various embodiments of the present disclosure. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0039] Before carrying out the description of the following specific embodiments, it may be advantageous to elaborate on the definitions of certain words and phrases used throughout this patent document.The term "coupling" and its derivatives refer to any direct or indirect communication between two or more elements, regardless of whether these elements are in physical contact with each other.The terms "send", "receive" and "communication" and their derivatives cover direct and indirect communication.The terms "include" and "comprise" and their derivatives mean including but not limited to.The term "or" is inclusive, meaning and / or.The phrase "associated with..." and its derivatives mean including, included in, connected to, interconnected with, included in, connected to or connected with, coupled to or coupled with, can communicate with, collaborate with, interweave, juxtapose, approach, bind to or bind with, have, have... attributes, have... relationships or have relationships with, etc.The term "controller" means any device, system or part thereof that controls at least one operation.Such a controller can be implemented in hardware, or implemented in a combination of hardware and software and / or firmware.The functions associated with any particular controller can be centralized or distributed locally or remotely. The phrase "at least one of" when used with a list of items means that different combinations of one or more of the listed items may be used, and only one item in the list may be needed. For example, "at least one of A, B, and C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C. For example, "at least one of A, B, or C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.

[0040] In addition, the various functions described below can be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and embodied in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, processes, functions, objects, classes, instances, related data or parts thereof suitable for implementation in a suitable computer-readable program code. The phrase "computer-readable program code" includes any type of computer code, including source code, object code and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disc (CD), a digital video disc (DVD) or any other type of memory. "Non-transitory" computer-readable media excludes wired, wireless, optical or other communication links that transmit temporary electrical signals or other signals. Non-transitory computer-readable media include media that can permanently store data and media that can store and rewrite data later, such as rewritable optical discs or erasable memory devices.

[0041] The terms used to describe the embodiments of the present application are not intended to limit and / or define the scope of the present application. For example, unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be the common meanings understood by people with ordinary skills in the field to which the present application belongs.

[0042] It should be understood that the words "first", "second" and the like used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Unless the context clearly indicates otherwise, the singular forms "a", "an" or "the" and the like do not indicate quantity limitation, but indicate the presence of at least one.

[0043] As used herein, any reference to "one example" or "example", "one embodiment" or "embodiment" means that a particular element, feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment. The phrases "in one embodiment" or "in an example" appearing in different places in the specification do not necessarily all refer to the same embodiment.

[0044] As used herein, "a portion" of something means "at least some" of that thing, and thus may mean less than all of that thing or all of that thing. Thus, "a portion" of a thing includes the entire thing as a special case, i.e., the entire thing is an example of a portion of a thing.

[0045] It will be further understood that the terms "include" or "comprises" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connected" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right", etc. are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0046] The various embodiments discussed below for describing the principles of the present disclosure in this patent document are intended to be illustrative only and should not be interpreted in any way as limiting the scope of the present disclosure. Those skilled in the art will appreciate that the principles of the present disclosure can be implemented in any appropriately arranged wireless communication system. For example, although the following detailed description of the embodiments of the present disclosure will be directed to LTE and 5G communication systems, those skilled in the art will appreciate that the main points of the present disclosure can also be applied to other communication systems with similar technical backgrounds and channel formats with slight modifications without substantially departing from the scope of the present disclosure. The technical solutions of the embodiments of the present application can be applied to various communication systems, for example, the communication system may include a global system for mobile communications (GSM) system, a code division multiple access (CDMA) system, a wideband code division multiple access (WCDMA) system, a general packet radio service (GPRS), a long term evolution (LTE) system, a LTE frequency division duplex (FDD) system, a LTE time division duplex (TDD), a universal mobile telecommunication system (UMTS), a world-wide interoperability for microwave access (WiMAX) communication system, a fifth generation (5G) system or a new radio (NR), etc. In addition, the technical solutions of the embodiments of the present application can be applied to future-oriented communication technologies. In addition, the technical solutions of the embodiments of the present application can be applied to future-oriented communication technologies.

[0047] The following description with reference to the accompanying drawings is provided to facilitate a comprehensive understanding of the various embodiments of the present disclosure as defined by the claims and their equivalents. This description includes various specific details to facilitate understanding but should be considered as exemplary only. Therefore, one of ordinary skill in the art will recognize that various changes and modifications can be made to the various embodiments described herein without departing from the scope and spirit of the present disclosure. In addition, for the sake of clarity and conciseness, descriptions of well-known functions and structures may be omitted.

[0048] The terms and expressions used in the following specification and claims are not limited to their dictionary meanings, but are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Therefore, it should be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustration purposes only and not for the purpose of limiting the present disclosure as defined in the appended claims and their equivalents.

[0049] It should be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.

[0050] The term "include" or "may include" refers to the presence of the corresponding disclosed functions, operations or components that can be used in various embodiments of the present disclosure, rather than limiting the presence of one or more additional functions, operations or features. In addition, the term "include" or "have" may be interpreted as indicating certain characteristics, numbers, steps, operations, constituent elements, components or combinations thereof, but should not be interpreted as excluding the possibility of the presence of one or more other characteristics, numbers, steps, operations, constituent elements, components or combinations thereof.

[0051] The term "or" used in various embodiments of the present disclosure includes any of the listed terms and all combinations thereof. For example, "A or B" may include A, may include B, or may include both A and B.

[0052] Unless defined differently, all terms (including technical terms or scientific terms) used in the present disclosure have the same meanings as understood by those skilled in the art described in the present disclosure. Common terms as defined in dictionaries are interpreted as having meanings consistent with the context in the relevant technical field, and should not be interpreted ideally or overly formally unless clearly defined in the present disclosure.

[0053] The following discussion Figures 1 to 13 The various embodiments used to describe the principles of the present disclosure in this patent document are for illustration only and should not be interpreted in any way as limiting the scope of the present disclosure. Those skilled in the art will appreciate that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0054] Figure 1 It is an exemplary system architecture 100 of System Architecture Evolution (SAE). User Equipment (UE) 101 is a terminal device used to receive data. Evolved Universal Terrestrial Radio Access Network (E-UTRAN) 102 is a radio access network, which includes a macro base station (eNodeB / NodeB) that provides a wireless network interface for the UE to access. The Mobility Management Entity (MME) 103 is responsible for managing the mobility context, session context and security information of the UE. The Serving Gateway (SGW) 104 mainly provides user plane functions, and the MME 103 and SGW 104 may be in the same physical entity. The Packet Data Network Gateway (PGW) 105 is responsible for functions such as billing and lawful interception, and may also be in the same physical entity as the SGW 104. The Policy and Charging Rules Function Entity (PCRF) 106 provides Quality of Service (QoS) policies and charging criteria. The General Packet Radio Service Support Node (SGSN) 108 is a network node device that provides routing for data transmission in the Universal Mobile Telecommunications System (UMTS). The Home Subscriber Server (HSS) 109 is the home subsystem of the UE and is responsible for protecting user information including the current location of the user equipment, the address of the service node, user security information, and the packet data context of the user equipment.

[0055] Figure 2 is an exemplary system architecture 200 according to various embodiments of the present disclosure. Other embodiments of the system architecture 200 can be used without departing from the scope of the present disclosure.

[0056] User equipment (UE) 201 is a terminal device used to receive data. The next generation radio access network (NG-RAN) 202 is a radio access network, which includes a base station (gNB or eNB connected to the 5G core network 5GC, the eNB connected to the 5GC is also called ng-gNB) that provides the UE with an access wireless network interface. The access control and mobility management function entity (AMF) 203 is responsible for managing the mobility context and security information of the UE. The user plane function entity (UPF) 204 mainly provides user plane functions. The session management function entity SMF 205 is responsible for session management. The data network (DN) 206 includes services such as operators, Internet access, and third-party services.

[0057] Figure 3 is an exemplary architecture of a base station according to various embodiments of the present disclosure. Other embodiments of the base station can be used without departing from the scope of the present disclosure.

[0058] In the NR system, in order to support network function virtualization and more efficient resource management and scheduling, the base station (gNB / ng-eNB) that provides a wireless network interface for the terminal (UE) can be further divided into a centralized unit gNB-CU / ng-eNB-CU (gNB central unit / ng-eNB central unit) and a distributed unit gNB-DU / ng-eNB-DU (gNB distributed unit / ng-eNB distributed unit) (referred to as CU and DU in the present invention), such as Figure 3 As shown in (a) in the figure. gNB-CU has radio resource control (RRC), service data adaptation protocol (SDAP: Service Data Adaptation Protocol) and packet data convergence protocol (PDCP) protocol layers, and ng-eNB-CU has RRC and PDCP layers. gNB-DU / ng-eNB-DU has radio link control protocol (RLC), medium access control (MAC) and physical layer, etc. There is a standardized public interface F1 between gNB-CU and gNB-DU, and a standardized public interface W1 between ng-eNB-CU and ng-eNB-DU. The F1 interface is divided into the control plane F1-C and the user plane F1-U. The transport network layer of F1-C is based on IP transmission. In order to transmit signaling more reliably, the SCTP protocol is added on top of IP. The protocol of the application layer is F1AP, see 3GPP TS38.473. SCTP can provide reliable application layer message transmission. The transport layer of F1-U is UDP / IP (UDP Internet Protocol, User Datagram Protocol / IP), and GTP-U (GPRS Tunnelling Protocol for the user plane) is used to carry the user plane protocol data unit PDU on top of UDP / IP. Furthermore, for gNB-CU, Figure 3As shown in (b), the gNB-CU may include gNB-CU-CP (control plane part of the centralized unit of the base station) and gNB-CU-UP (user plane part of the centralized unit of the base station). The gNB-CU-CP includes the control plane function of the base station, with RRC and PDCP protocol layers, and the gNB-CU-UP includes the user plane function of the base station, with SDAP and PDCP protocol layers. The standardized public interface E1 is used between gNB-CU-CP and gNB-CU-UP, and the protocol is E1AP, see 3GPP TS38.463. The interface between the control plane part of the centralized unit of the base station and the distributed unit of the base station is the F1-C interface, i.e., the control plane interface of F1, and the interface between the user plane part of the centralized unit of the base station and the distributed unit of the base station is the F1-U interface, i.e., the user plane interface of F1. In addition, in the NR system, the base station that provides the E-UTRA user plane and control plane accessing the 5G core network is called ng-eNB. In order to support virtualization, this base station (ng-eNB) can also be further divided into a centralized unit ng-eNB-CU (gNB central unit / ng-eNBcentral unit) and a distributed unit ng-eNB-DU (gNB distributed unit / ng-eNB distributedunit) (abbreviated as CU and DU in the present invention), such as Figure 3 As shown in (c). ng-eNB-CU has RRC and PDCP layers. gNB-DU / ng-eNB-DU has radio link control protocol (RLC), medium access control (MAC) and physical layer, etc. There is a standardized public interface W1 between ng-eNB-CU and ng-eNB-DU. The W1 interface is divided into control plane W1-C and user plane W1-U. The transport network layer of W1-C is based on IP transmission. In order to transmit signaling more reliably, the SCTP protocol is added on top of IP. The protocol of the application layer is W1AP, see 3GPP TS37.473. The transport layer of W1-U is UDP / IP, and GTP-U is used to carry user plane protocol data unit PDU on top of UDP / IP.

[0059] Compared with 4G, 5G communication technology has a faster transmission speed, so it can provide users with more types of communication services. Extended Reality (XR) business is regarded as a key application service to promote the development of 5G technology. It is a general term for the three major business types of augmented reality AR, virtual reality VR, and mixed reality MR. XR business has high requirements for transmission speed and latency, so more network resources are needed to support the normal operation of the business. At the same time, for the portability of XR devices, the size of the battery is greatly limited, and how to reduce energy consumption has also become a considerable challenge. Therefore, in order to improve the user experience of XR users, it is necessary to conduct more in-depth research on reducing power consumption, increasing network capacity, and improving XR perception.

[0060] In order to better carry out research in the XR field, the concept of packet data unit set (PDU set, PDU set) is proposed. A PDU set is composed of one or more PDUs. A PDU set can be a frame (a frame) or a video slice (a video slice) in an XR service. A PDU set can only be mapped to a QoS (Quality of Service) flow, and the relevant parameters of all PDU sets on a QoS flow are the same. The relevant parameters of the PDU set are such as PDU Set Delay Budget (PDU Set Delay Budget, PSDB), PDU Set Error Rate (PDU Set Error Rate, PSER) and PDU Set Integrated Handling Indication (PDU Set Integrated Handling Indication, PSIHI).

[0061] The QoS parameters of the PDU set are sent by the core network's session management function entity SMF to the access network NG-RAN through the access mobility management function entity AMF. When NG-RAN receives the QoS parameters of at least one PDU set, NG-RAN needs to start the QoS processing of the PDU set. If NG-RAN cannot configure the QoS parameters of the PDU set, it will process it according to the data of the ordinary QoS flow. If the UE moves between an NG-RAN that supports PDU sets and an NG-RAN that does not support PDU sets, how to dynamically start the QoS parameter configuration of the data set and the user plane information transmission to improve the transmission performance of XR service data and meet the needs of XR services is a problem that needs to be solved.

[0062] In addition, when the UE moves, how to reduce the transmission of XR data, save air interface resources, and improve the transmission efficiency of XR data is another problem to be solved.

[0063] The present disclosure provides a method executed by a second node in a communication system, the method comprising: sending a first message to a third node, the first message comprising first indication information, the first indication information being used to indicate whether the second node supports packet data unit (PDU) set processing of an extended reality (XR) service; and receiving a second message from the third node, wherein if the first indication information indicates that the second node supports PDU set processing of the XR service, the second message comprises XR service configuration information.

[0064] The present disclosure also provides a method executed by a third node in a communication system, the method comprising: receiving a first message from a second node, the first message comprising first indication information, the first indication information being used to indicate whether the second node supports packet data unit (PDU) set processing of an extended reality (XR) service; and sending a second message to the second node, wherein if the first indication information indicates that the second node supports PDU set processing of the XR service, the second message comprises XR service configuration information.

[0065] The present disclosure also provides a method executed by a first node in a communication system, the method comprising: sending a third message to a second node, the third message including or not including extended reality XR service configuration information corresponding to the first node; receiving a fourth message from the second node, the fourth message including second indication information, and the second indication information is used to indicate whether the second node supports packet data unit PDU set processing of the extended reality XR service.

[0066] Through the above method, the UE can move between the NG-RAN that supports PDU sets and the NG-RAN that does not support PDU sets, and can dynamically start the QoS parameter configuration of the data set to improve the transmission performance of XR service data and meet the needs of XR services.

[0067] The present disclosure provides a method executed by a second node in a communication system, the method comprising: receiving an eighth message from a first node, the eighth message comprising a sequence number PSSN of a packet data unit PDU set; and executing a corresponding operation based on the eighth message.

[0068] Through the above embodiments, when the UE moves, the sending of XR data can be reduced, the resources of the air interface can be saved, and the transmission efficiency of the XR data can be improved.

[0069] It is understandable that the above technical problems and technical solutions are only shown as examples, and the present disclosure is not limited thereto. Any technical problem that can be solved by the present disclosure and any variation based on the present disclosure belong to the scope of protection of the present disclosure.

[0070] Exemplary embodiments of the present disclosure are further described below in conjunction with the accompanying drawings.

[0071] The text and drawings are provided as examples only to help understand the present disclosure. They should not be interpreted as limiting the scope of the present disclosure in any way. Although certain embodiments and examples have been provided, it will be apparent to those skilled in the art based on what is disclosed herein that the embodiments and examples shown may be changed without departing from the scope of the present disclosure.

[0072] The NR and LTE in the following description are merely examples of different radio access technologies RAT, and may also be other RATs. NG-RAN, gNB, AMF, SMF are merely examples of different nodes, and may also be other nodes, but the present invention is not limited to this.

[0073] Please refer to Figure 4 , Figure 4 It is a schematic diagram for describing a process of a user equipment UE moving from a first node to a second node according to various embodiments of the present disclosure. The first node (i.e., a source base station serving the UE) supports XR services, and when the UE is located at the source base station, the UE is receiving the XR service. In this example, the UE moves to the second node (i.e., a destination base station), and the destination base station may or may not support the XR service.

[0074] The specific process of the embodiment of the present disclosure is as follows: Figure 4 As shown. Figure 4 As shown, the method of this embodiment may include one or more steps from step S300 to step S312.

[0075] Step 300: SMF configures sessions related to base station XR.

[0076] SMF sends a message to the base station (i.e., the first node) to configure the XR service through AMF. The message sent by AMF may be a PDU session establishment request or a UE context establishment request, etc. The message carries the SM container sent by SMF. The SM container carries the configuration information of the XR service, which may include the PDU session identifier, the QoS flow identifier, the service quality requirements of the QoS flow, the period of XR data, the data burst arrival time, the data survival time, the jitter configuration, etc. The message may also include the QoS parameter configuration of the packet data unit set of the XR service (the QoS parameters of the PDU set). This step is required for the following embodiments and is similar, so it is omitted in the description of the following embodiments.

[0077] The QoS parameter configuration of (one or more) PDU sets is transmitted from the core network to the access network. The parameters related to the PDU set include at least one of the following information:

[0078] ■PSIHI: Indicates whether the application layer needs all the PDUs in the PDU set to use the PDU set. Only when all the PDUs are received can the application layer correctly restore the information carried by the PDU. This means that if a PDU in a PDU set is lost, the remaining PDUs in the entire PDU set will be useless even if they are received and need to be discarded.

[0079] ■PSDB: defines an upper limit on the delay that a PDU set may experience at the UPF for transmission between the UE and the N6 termination point, i.e., the duration between the reception time of the first PDU (at the N6 termination point for DL ​​or at the N6 termination point for UE for UL) and the time when all PDUs of the PDU set have been successfully received (at the UE for DL ​​or at the N6 termination point for UL). PSDB applies to the DL PDU set received by the PSA-UPF (PDU Session Anchor User Plane Function) on the N6 interface, and to the UL PDU set sent by the UE.

[0080] ■PDER: Defines the set of PDUs that have been processed by the transmitter of the link layer protocol (e.g., RLC in the RAN for 3GPP access) but not successfully delivered to the upper layer by the corresponding receiver (e.g., PSER). Therefore, PSER defines an upper limit on the loss rate of the set of non-congestion related PDUs. The purpose of PSER is to allow appropriate link layer protocol configuration (e.g., RLC and HARQ in the RAN for 3GPP access).

[0081] The XR service session is established, and the UPF sends the PDU of the XR service to the access network. The GPRS Tunneling Protocol (GTP) is used between the UPF and the access network. The UPF sends a GTP-U data packet to the access network. The GTP user data packet carries header information and data information. In the header part, XR-related information is also added. The XR-related information can include at least one of the following information:

[0082] ■PDU set sequence number (PSSN). PDUs belonging to the same PDU set have the same PDU set sequence number (SN). The PDU set SN is incremented and indicates the PDU set to which the PDU belongs.

[0083] ■PDU sequence number (PDU SN). A PDU set can contain multiple PDUs. The PDU SN indicates the sequence number of the PDU in a certain PDU set.

[0084] ■Indication information indicating the last PDU in a PDU set, using one bit to indicate whether the PDU is the last PDU in this PDU set.

[0085] ■The size of a PDU set indicates how many bytes a PDU set has.

[0086] ■PDU set importance indication information. Different PDU sets can have different importance, which can be represented by PDUset importance (PDU set importance, PSI), whose value can be, for example, high / medium / low, or 0-7. In addition, different PDU sets mapped to the same QoS flow can also have different PSIs. PSI can be told to RAN by UPF through the GTP-U header. When network congestion occurs on the RAN side, the corresponding PDU set can be discarded according to the PSI value (for example, some PDU sets with smaller PSI values ​​can be discarded), so as to alleviate or solve the network congestion.

[0087] Step 301: The first node sends a switching request message to the second node.

[0088] The source base station decides to switch the UE to the destination base station based on the UE measurement results. The switching request message contains one or more of the following: the identifier of the destination cell, the list of PDU sessions in progress of the UE, the PDU session list contains the PDU session identifier (PDU session ID), the QoS flow identifier (QoS flow ID), the service quality requirements of the QoS flow, and the uplink data receiving address, such as the transport layer IP address and the tunnel identifier TEID. This information is allocated by the core network user plane node UPF. The message also contains the source base station's information about data forwarding. The data forwarding information contains recommendations for data forwarding for uplink data and / or downlink data of a certain session or a certain DRB.

[0089] For XR services, the switching request message also includes the period of XR data transmitted on the QoS flow, data burst arrival time, data survival time, jitter configuration, etc. The switching request also includes the QoS parameter configuration of the packet data unit set of the XR service, that is, it includes at least one of the following information: QoS flow ID, type of PDU set, identifier of PDU set, PSDB, PDER, PSIHI.

[0090] Step 302: The second node sends a handover response message to the first node.

[0091] The destination base station establishes resources corresponding to the session based on the session related information contained in the handover request message. The session related information includes the session identifier, the session includes the QoS flow information, and the data forwarding suggestion. Based on the forwarding suggestion, the destination base station decides whether data forwarding is required for the session and / or for the DRB. If data forwarding is required, the destination base station allocates a data forwarding address for the session or DRB.

[0092] The destination base station sends a handover response message to the source base station. The message carries the UE's identifier on the Xn interface, the bearer information or PDU session information received at the destination base station, data forwarding information, and a handover command message to be sent to the UE. The data forwarding information includes the identifier of the QoS flow to which data is to be forwarded, the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the PDU session, and may also include the identifier of the DRB to which data is to be forwarded, and the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the DRB.

[0093] For the XR service being carried out by the UE, if the destination base station supports the XR service, the destination base station saves and uses the relevant configuration parameters of the XR service, including the jitter configuration of the XR service, the QoS parameter configuration of the PDU set of the XR service, etc., and schedules data according to the relevant configuration parameters of the XR service. In the switching response message, the destination base station may include indication information of the acceptance of the XR QoS parameters, or include indication information that the destination base station supports the XR service. Through this indication information, the source base station knows that the destination base station supports the XR service. If the destination base station decides on the data forwarding of the XR service and includes data forwarding information in the switching response message, the source base station sends the data to be forwarded to the data forwarding address indicated by the destination base station according to the data forwarding information. When forwarding data to the destination base station, the source base station may include XR-related information in the GTP header.

[0094] For the XR service being carried out by the UE, if the destination base station does not support the XR service, the destination base station may not be able to parse and understand the relevant configuration parameters of the XR service, including the jitter configuration of the XR service and the QoS parameter configuration of the PDU set of the XR service. At this time, the destination base station will treat the XR service as an ordinary service and establish a QoS data radio bearer DRB according to the QoS parameters corresponding to the original QoS flow, that is, treat the QoS flow of the XR service as an ordinary QoS flow. In the handover response message, the destination base station does not include any information related to XR. By not including any XR-related indication information, the source base station can know that the destination base station does not support the XR service, that is, the destination base station treats the XR service as an ordinary session or an ordinary QoS flow. If the destination base station determines the data forwarding of the XR-related session and includes data forwarding information in the handover response message, the source base station sends the data to be forwarded to the data forwarding address indicated by the destination base station according to the data forwarding information. When forwarding data to the destination base station, the source base station may not include XR-related information in the GTP header. This method can reduce unnecessary information contained in the data packet header, reduce the redundancy of the packet header, save data forwarding time and the required transport layer resources, and improve the overall system performance.

[0095] If it is a conditional handover, the conditional handover configuration sent by the destination base station to the UE may also carry indication information on whether the destination base station supports XR services. In conditional handover, the source base station prepares multiple destination base stations, and each destination base station includes the indication information on whether the base station supports XR in the RRC message sent to the UE. After the UE receives the conditional handover configuration, the UE can refer to the information on whether the candidate base station supports XR to decide which candidate base station to select as the destination base station.

[0096] Step 303: The source base station sends a handover command to the UE.

[0097] The source base station sends the handover command sent by the target base station to the UE.

[0098] Step 304: The source base station sends an SN status transmission message to the destination base station.

[0099] During a normal handover process, the source base station may suspend data transmission and reception, stop allocating PDCP (Packet Data Convergence Protocol) sequence numbers to downlink service data units SDU (Protocol Data Unit), and stop sending uplink SDUs to the core network.

[0100] The message of step 304 carries the identifier of the DRB, the uplink count value (COUNT value) and the downlink COUNT value of the DRB. The COUNT value includes the PDCP SN and the hyperframe number (HFN number). After receiving the value, the destination base station assigns the PDCP sequence number included in the DL COUNT value to the first downlink data packet that has not been assigned a PDCP sequence number. If the source base station accepts the uplink data forwarding requested by the destination base station, the message may also include the reception status of the lost or received uplink SDU.

[0101] For the XR service being carried out by the UE, the processing done by the source base station is the same as that of ordinary services. There is one difference. Depending on whether the destination base station supports the XR service, the source base station can include or exclude XR-related information in the GTP header when forwarding XR data. This method can reduce unnecessary information in the data packet header, reduce the redundancy of the packet header, save data forwarding time and the required transport layer resources, and improve the overall system performance.

[0102] Step 305: The UE synchronizes with the target cell and sends a handover completion message to the target base station.

[0103] As mentioned above, when selecting a destination cell, the UE can refer to whether the destination cell / destination base station supports XR services. When the UE has an ongoing XR service, it can select a base station that supports the XR service as the destination base station on the premise that the conditional switching is met.

[0104] Step 306: The target base station sends a path switching request message to the core network AMF.

[0105] The path switch request message contains the UE's location information and the PDU session list switched to the target base station. The UE's location information contains the unique identifier of the cell where the UE is located and the tracking area identifier where the UE is located. The specific information of the PDU session switched to the target base station is contained in the N2 SM container, which contains the user plane address and QoS flow information.

[0106] If the destination base station supports XR services, the message also includes indication information that the destination base station supports XR services, which includes indication information that XR QoS parameters are accepted, or through an explicit indication information. The indication information that XR QoS parameters are accepted can be an indication that the QoS corresponding to the PDU set of a certain XR service is accepted. The explicit indication information is an indication that the base station supports XR services, and the absence of the indication information means that the base station does not support it, or through an indication to indicate whether the base station supports XR services.

[0107] If the target base station does not support the XR service, the message does not include indication information related to the XR, or includes indication information indicating that the base station does not support the XR service.

[0108] The indication information in the above step can be sent from the base station to the SMF through the N2 SM container, or included outside the SM container and sent to the AMF, and then the AMF sends it to the SMF through step 307.

[0109] Step 307: AMF sends a session modification request message to SMF.

[0110] The AMF sends a message to the SMF, which carries the above-mentioned N2 SM container. The information in the container is parsed and saved by the SMF. The message may also include the location information of the UE. Or the message may also include indication information that the destination base station supports XR.

[0111] Step 308: SMF sends a session modification request message to UPF.

[0112] SMF sends a session modification request message to UPF. The message includes the downlink data receiving address assigned by the destination base station, the indication information that the destination base station supports XR, or the indication information indicating whether UPF includes XR-related information in the GTP header.

[0113] If the destination base station does not support XR, the UPF may not include XR-related information in the GTP header when sending a data packet to the destination base station. As mentioned above, the XR-related information includes the sequence number of the PDU set (PDU set), the sequence number of the PDU, the indication information indicating the last PDU of the PDU set, the size of the PDU set, and one or more of the indication information of the importance of the PDU set. In this way, unnecessary information included in the data packet header can be reduced, the redundancy of the packet header can be reduced, the time for data forwarding and the required transport layer resources can be saved, and the overall system performance can be improved.

[0114] Step 309: UPF sends a session modification response message to SMF.

[0115] UPF sends a response message to SMF. The message may include the receiving address of the uplink data allocated by UPF.

[0116] Step 310: SMF sends a session modification response message to AMF.

[0117] SMF sends a response message to AMF. The message may contain an N2 SM container, which contains the uplink data receiving address allocated by UPF. The data receiving address contains the transport layer IP address and GTP tunnel identifier. The container also contains the received QoS flow information, including alternative QoS parameters for the QoS flow.

[0118] Step 311: AMF sends a path switching response message to the destination base station.

[0119] The AMF sends a response message to the target base station, which includes the N2 SM container received in step 310.

[0120] The path switching response message contains the UE's identification on the NG interface, the bearer information of the successful switching or the identification of the PDUSession, and the N2 SM container. The N2 SM container contains the content configured by the SMF and is transparent to the AMF. The container contains the information of the user plane allocated by the UPF and the QoS information.

[0121] Step 312: The target base station sends a UE context release request message to the source base station.

[0122] After the UE is switched to the target base station, the target base station may send a UE context release request message to request the source base station to release the stored relevant information and resources of the UE.

[0123] So far, the switching process of the above embodiment is completed.

[0124] Through the above embodiments, the UE can move between an NG-RAN that supports PDU sets and an NG-RAN that does not support PDU sets, and can dynamically start the QoS parameter configuration of the data set to improve the transmission performance of XR service data and meet the needs of XR services.

[0125] Please refer to Figure 5 , Figure 5 It is a schematic diagram for describing another process of a user equipment UE moving from a first node to a second node according to various embodiments of the present disclosure. Among them, the first node (i.e., the source base station serving the UE) does not support the XR service, that is, the XR service is transmitted as a normal service at the source base station. In this embodiment, the UE moves to the second node, i.e., the destination base station, and the destination base station can support the XR service. At this time, establishing the XR service as soon as possible can improve the user experience of the XR service.

[0126] The specific process of the embodiment of the present disclosure is as follows: Figure 5 As shown. Figure 5 As shown, the method of this embodiment may include one or more steps from step S401 to step S412.

[0127] Step 401: The first node sends a switching request message to the second node.

[0128] The source base station decides to switch the UE to the destination base station based on the UE measurement results. The switching request message contains one or more of the following: the identifier of the destination cell, the list of PDU sessions in progress of the UE, the PDU session list contains the PDU session identifier (PDU session ID), the QoS flow identifier (QoS flow ID), the service quality requirements of the QoS flow, and the uplink data receiving address, such as the transport layer IP address and the tunnel identifier TEID. This information is allocated by the core network user plane node UPF. The message also contains the source base station's information about data forwarding. The data forwarding information contains recommendations for data forwarding for uplink data and / or downlink data of a certain session or a certain DRB.

[0129] For XR services, the source base station transmits them as ordinary services. The switching request message does not contain any special parameters for the XR services, that is, it does not contain the configuration of XR service jitter, etc., and does not contain the QoS parameter configuration of the packet data unit set of the XR service.

[0130] Step 402: The second node sends a switching response message to the first node.

[0131] The destination base station establishes resources corresponding to the session based on the session related information contained in the handover request message. The session related information includes the session identifier, the session includes the QoS flow information, and the data forwarding suggestion. Based on the forwarding suggestion, the destination base station decides whether data forwarding is required for the session and / or for the DRB. If data forwarding is required, the destination base station allocates a data forwarding address for the session or DRB.

[0132] The destination base station sends a handover response message to the source base station. The message carries the UE's identifier on the Xn interface, the bearer information or PDU session information received at the destination base station, data forwarding information, and a handover command message to be sent to the UE. The data forwarding information includes the identifier of the QoS flow to which data is to be forwarded, the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the PDU session, and may also include the identifier of the DRB to which data is to be forwarded, and the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the DRB.

[0133] Since the handover request does not include any XR-related specific information, the target base station does not know whether the UE is performing an XR service, and the handover response message does not include XR indication information or XR-related specific information.

[0134] If it is a conditional handover, the conditional handover configuration sent by the destination base station to the UE may also carry indication information on whether the destination base station supports XR services. In conditional handover, the source base station prepares multiple destination base stations, and each destination base station includes the indication information on whether the base station supports XR in the RRC message sent to the UE. After the UE receives the conditional handover configuration, the UE can refer to the information on whether the candidate base station supports XR to decide which candidate base station to select as the destination base station.

[0135] Step 403: The source base station sends a handover command to the UE.

[0136] The source base station sends the handover command sent by the target base station to the UE.

[0137] If it is a conditional handover, the conditional handover configuration sent by the destination base station to the UE may also carry indication information on whether the destination base station supports XR services. In conditional handover, the source base station prepares multiple destination base stations, and each destination base station includes the indication information on whether the base station supports XR in the RRC message sent to the UE. After the UE receives the conditional handover configuration, the UE can refer to the information on whether the candidate base station supports XR to decide which candidate base station to select as the destination base station.

[0138] Step 404: The source base station sends an SN status transmission message to the destination base station.

[0139] During a normal handover process, the source base station may suspend data transmission and reception, stop allocating PDCP (Packet Data Convergence Protocol) sequence numbers to downlink service data units SDU (Protocol Data Unit), and stop sending uplink SDUs to the core network.

[0140] The message in step 304 carries the identifier of the DRB, the uplink count value (COUNT value) and the downlink COUNT value of the DRB. After receiving the value, the destination base station assigns the PDCP sequence number contained in the DL COUNT value to the first downlink data packet that has not been assigned a PDCP sequence number. If the source base station accepts the uplink data forwarding requested by the destination base station, the message may also include the reception status of the lost or received uplink SDU.

[0141] Step 405: The UE synchronizes with the target cell and sends a handover completion message to the target base station.

[0142] When selecting a destination cell, the UE can refer to whether the destination cell / destination base station supports XR services. When the UE has an ongoing XR service, it can select a base station that supports XR services as the destination base station if the conditional switching is met.

[0143] Step 406: The target base station sends a path switching request message to the core network AMF.

[0144] The path switch request message contains the UE's location information and the PDU session list switched to the target base station. The UE's location information contains the unique identifier of the cell where the UE is located and the tracking area identifier where the UE is located. The specific information of the PDU session switched to the target base station is contained in the N2 SM container, which contains the user plane address and QoS flow information.

[0145] If the target base station supports the XR service, the message also includes indication information that the target base station supports the XR service, indicating that the base station supports the XR service, or indicates whether the base station supports the XR service through an indication.

[0146] The indication information in the above step can be sent from the base station to the SMF through the N2 SM container, or included outside the SM container and sent to the AMF, and then the AMF sends it to the SMF through step 407.

[0147] Step 407: AMF sends a session modification request message to SMF.

[0148] The AMF sends a message to the SMF, which carries the above-mentioned N2 SM container. The information in the container is parsed and saved by the SMF. The message may also include the location information of the UE. Or the message may also include indication information that the destination base station supports XR.

[0149] Step 408: SMF sends a session modification request message to UPF.

[0150] SMF sends a session modification request message to UPF. The message includes the downlink data receiving address assigned by the destination base station, the indication information that the destination base station supports XR, or the indication information indicating whether UPF includes XR-related information in the GTP header.

[0151] If the destination base station supports XR, UPF knows that the source base station does not support XR services. When UPF sends a data packet to the source base station, XR-related information is not included in the GTP header. When UPF knows that the destination base station supports XR services, it can include XR-related information in the GTP header when sending a data packet to the destination base station. In this way, the base station can schedule and process the PDU set of XR service data, improve the quality of XR services, and improve user satisfaction with XR services.

[0152] Step 409: UPF sends a session modification response message to SMF.

[0153] UPF sends a response message to SMF. The message may include the receiving address of the uplink data allocated by UPF.

[0154] Step 410: SMF sends a session modification response message to AMF.

[0155] SMF sends a response message to AMF. The message may contain an N2 SM container, which contains the uplink data receiving address allocated by UPF. The data receiving address contains the transport layer IP address and GTP tunnel identifier. The container also contains the received QoS flow information, including alternative QoS parameters for the QoS flow.

[0156] When SMF knows that the destination base station supports XR services, but the source base station does not, SMF can include relevant configuration information of the XR service in the N2 SM container. The relevant configuration information includes the QoS flow identifier of the XR service, the period of the XR data transmitted on the QoS flow, the data burst arrival time, the data survival time, the jitter configuration, etc. The relevant configuration information also includes the QoS parameter configuration of the packet data unit set of the XR service, that is, it includes at least one of the following information: QoSflow ID, the type of PDU set, the identifier of the PDU set, PSDB, PDER, PSIHI. In this way, the destination base station can obtain the unique configuration information of XR as soon as possible, and can schedule and process data as soon as possible according to the characteristics of XR, improve the performance of the XR service, and improve the customer satisfaction of the XR service.

[0157] It is also possible to modify the relevant configuration information of the XR service through a separate session modification process later, and in a separate process thereafter, notify the destination base station of the jitter configuration of the XR service and the QoS parameter configuration of the packet data unit set of the XR service.

[0158] Step 411: AMF sends a path switching response message to the destination base station.

[0159] The AMF sends a response message to the target base station, which includes the N2 SM container received in step 310.

[0160] The path switching response message contains the UE's identification on the NG interface, the bearer information of the successful switching or the identification of the PDUSession, and the N2 SM container. The N2 SM container contains the content configured by the SMF and is transparent to the AMF. The container contains the information of the user plane allocated by the UPF and the QoS information.

[0161] Step 412: The target base station sends a UE context release request message to the source base station.

[0162] After the UE is switched to the target base station, the target base station may send a UE context release request message to request the source base station to release the stored relevant information and resources of the UE.

[0163] So far, the switching process of the above embodiment is completed.

[0164] Through the above embodiments, the UE can move between the NG-RAN that does not support PDU aggregation and the NG-RAN that supports PDU aggregation, and can dynamically start the QoS parameter configuration of the data set, provide the QoS parameter configuration to the NG-RAN as early as possible, improve the transmission performance of the XR service data, and meet the needs of the XR service.

[0165] Please refer to Figure 6 , Figure 6 It is a schematic diagram for describing another process of a user equipment UE moving from a first node to a second node according to various embodiments of the present disclosure. The first node (i.e., a source base station serving the UE) supports XR services, and when the UE is located at the source base station, the UE is receiving the XR services. In this example, the UE moves to the second node (i.e., a destination base station), wherein the destination base station may or may not support the XR services. The first node and the second node are separate base station structures.

[0166] The specific process of the embodiment of the present disclosure is as follows: Figure 6 As shown. Figure 6 As shown, the method of this embodiment may include one or more steps from step S501 to step S514.

[0167] Step 501: A first node sends a switching request message to a second node.

[0168] The first node is the centralized control entity of the source base station (e.g., the source gNB-CU-CP). Based on the UE measurement results, it decides to switch the UE to the second node. The second node is the centralized control entity of the target base station (e.g., the target gNB-CU-CP). The switching request message includes one or more of the following: the identifier of the target cell, the list of PDU sessions in progress of the UE, the PDU session list includes the PDU session identifier (PDU session ID), the QoS flow identifier (QoS flow ID), the service quality requirements of the QoS flow, and the uplink data receiving address, such as the transport layer IP address and the tunnel identifier TEID. This information is allocated by the core network user plane node UPF. The message also includes information about data forwarding from the first node. The data forwarding information includes a recommendation for data forwarding for the uplink data and / or downlink data of a certain session or a certain DRB.

[0169] For XR services, the switching request message also includes the period of XR data transmitted on the QoS flow, data burst arrival time, data survival time, jitter configuration, etc. The switching request also includes the QoS parameter configuration of the packet data unit set of the XR service, that is, it includes at least one of the following information: QoS flow ID, type of PDU set, identifier of PDU set, PSDB, PDER, PSIHI.

[0170] Step 502: The second node sends a bearer context establishment request message to a destination user plane entity.

[0171] The user plane entity may be the target gNB-CU-UP. The following description is made by taking the second node being the target gNB-CU-CP and the user plane entity being the target gNB-CU-UP as an example. The target gNB-CU-CP sends a bearer context establishment request message to the target gNB-CU-UP. The message includes the identifier of the UE on the E1 interface, encryption information, the service operator identifier PLMN ID, the identifier of the UE on the access network RAN ​​ID, the identifier of the base station separation unit DU, and the PDU session list to be established. The PDU session list includes the PDU session identifier, S-NSSAI, encryption indication, uplink transport layer address, such as IP address and TEID. This information is allocated by the core network user plane node UPF to receive uplink data. The PDU session list also includes a DRB list to be established. The DRB list includes a DRB identifier, a quality of service (QoS) of the DRB, SDAP configuration, PDCP configuration, PDCP sequence number status information, Cell group information, and a QoS flow list to be established. The gNB-CU-CP determines the mapping of the QoS flow to the data radio channel. The QoS flow list includes the QoS flow identifier, the quality of service QoS of the QoS flow, etc.

[0172] For the XR service being performed by the UE, if the target gNB-CU-CP supports the processing of PDU sets, the target gNB-CU-CP saves and uses the configuration parameters related to the PDU set of the XR service. The message in step 502 includes the configuration parameters related to the PDU set of the XR service.

[0173] For the XR service being performed by the UE, if the target gNB-CU-CP does not support PDU set processing, the target gNB-CU-CP may not be able to parse and understand the relevant configuration parameters of the PDU set. At this time, the target gNB-CU-CP will treat the XR service as an ordinary service and establish a QoS data radio bearer DRB according to the QoS parameters corresponding to the original QoS flow. The bearer context establishment request message does not contain any information related to the PDU set.

[0174] Step 503: The target gNB-CU-UP sends a bearer establishment response message to the second node (i.e., the target gNB-CU-CP).

[0175] The target gNB-CU-UP sends a bearer context establishment response message to the target gNB-CU-CP. The message contains the UE's E1 interface identifier, the successfully established PDU session list, the PDU session list contains the PDU session identifier, the encryption result, and the downlink transport layer address, which is allocated by the gNB-CU-UP and is used to receive downlink data sent by the core network. The message also contains the successfully established DRB list, which contains the DRB identifier, DRB data forwarding information, and the uplink user plane information of the DRB. The uplink user plane information contains the user plane transport layer address, cell group identifier, and other information. The uplink user plane address is allocated by the target gNB-CU-CP and is used to receive uplink data sent by the DU.

[0176] For the XR service being performed by the UE, if the target gNB-CU-UP supports PDU aggregation processing, the message in step 503 includes indication information that the gNB-CU-UP supports PDU aggregation processing, which may be implicitly indicated by including an indication information of XR QoS parameter acceptance in the message, or by an explicit indication information, indicating that the target gNB-CU-UP supports PDU aggregation and / or does not support PDU aggregation. The indication information of XR QoS parameter acceptance may indicate that the QoS corresponding to the PDU aggregation of a certain XR service is accepted.

[0177] For the XR service being performed by the UE, if the target gNB-CU-UP does not support PDU aggregation, the message does not contain the indication information of the XRPDU aggregation, or contains indication information indicating that the target gNB-CU-UP does not support PDU aggregation.

[0178] The target gNB-CU-UP can know whether conditional switching is performed from the CHO indication included in the bearer context establishment request message. If it is a conditional switching, the target gNB-CU-UP response message can also carry indication information on whether the target gNB-CU-UP supports the PDU set. It is sent by the second node to the UE through the first node. In conditional switching, the first node prepares multiple target base stations, and each target base station includes the indication information of whether the base station supports PDU Set in the RRC message sent to the UE. After the UE receives the configuration of conditional switching, the UE can refer to the information on whether the candidate base station supports the PDU set to decide which candidate base station to select as the target base station.

[0179] The process between gNB-CU-CP and gNB-DU is omitted here. Similarly, the gNB-DU can include the indication information of XR QoS parameter acceptance in the UE context establishment response message to implicitly indicate that the gNB-DU supports the PDU set, or through an explicit indication information, indicate that the gNB-DU supports the PDU set and / or does not support the PDU set. The indication information of XR QoS parameter acceptance can indicate that the QoS corresponding to the PDU set of a certain XR service is accepted.

[0180] Step 504: The second node sends a switching response message to the first node.

[0181] The target gNB-CU-CP establishes resources corresponding to the session based on the session related information contained in the handover request message. The session related information includes the session identifier, the session includes the QoS flow information, and the data forwarding suggestion. Based on the forwarding suggestion, the target gNB-CU-CP determines whether data forwarding is required for the session and / or for the DRB. If data forwarding is required, the target gNB-CU-CP allocates a data forwarding address for the session or DRB.

[0182] The target gNB-CU-CP sends a handover response message to the source gNB-CU-CP. The message carries the UE's identifier on the Xn interface, the bearer information or PDU session information received at the target gNB-CU-CP, data forwarding information, and a handover command message to be sent to the UE. The data forwarding information includes the identifier of the QoS flow to which data is to be forwarded, the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the PDU session, and may also include the identifier of the DRB to which data is to be forwarded, and the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the DRB.

[0183] For the XR service being performed by the UE, if the target base station supports PDU set processing, the target base station supports it, which means that gNB-CU-CP, gNB-CU-UP, and gNB-DU all support PDU set processing. The target base station saves and uses the configuration parameters related to the PDU set of the XR service, including the jitter configuration of the XR service, the QoS parameter configuration of the PDU set of the XR service, etc., and schedules data according to the relevant configuration parameters of the XR service. In the handover response message, the target gNB-CU-CP may include indication information of XR QoS parameter acceptance, or include indication information that the target base station supports the XR service, indicating that the target base station supports PDU set and / or does not support PDU set. Through this indication information, the source gNB-CU-CP knows that the target base station supports PDU set processing. If the target gNB-CU-CP determines the data forwarding of the XR service and includes data forwarding information in the handover response message, the source gNB-CU-CP sends the data to be forwarded to the data forwarding address indicated by the target gNB-CU-CP according to the data forwarding information. When forwarding data to the destination gNB-CU-CP, the source gNB-CU-CP may include XR-related information in the GTP header.

[0184] For the XR service being performed by the UE, if the target base station does not support PDU aggregation, the target base station does not support it, which means that one of the gNB-CU-CP, gNB-CU-UP, and gNB-DU does not support PDU aggregation. The target gNB-CU-CP may not be able to parse and understand the configuration parameters related to the PDU aggregation of the XR service, including the jitter configuration of the XR service and the QoS parameter configuration of the PDU aggregation of the XR service. At this time, the target gNB-CU-CP will treat the XR service as an ordinary service and establish a QoS data radio bearer DRB according to the QoS parameters corresponding to the original QoS flow, that is, treat the QoS flow of the XR service as an ordinary QoS flow. In the handover response message, the target gNB-CU-CP does not include any information related to the XR PDU aggregation. By not including any XR-related indication information, the source gNB-CU-CP can know that the target base station does not support PDU aggregation, that is, the target base station treats the XR service as an ordinary session or ordinary QoS flow. If the target gNB-CU-CP determines the data forwarding of the XR-related session and includes the data forwarding information in the handover response message, the source gNB-CU-CP sends the data to be forwarded to the data forwarding address indicated by the target gNB-CU-CP according to the data forwarding information. When forwarding data to the target gNB-CU-CP, the source gNB-CU-CP may not include XR-related information in the GTP header. In this way, unnecessary information in the data packet header can be reduced, the redundancy of the packet header can be reduced, the time for data forwarding and the required transport layer resources can be saved, and the overall system performance can be improved.

[0185] If it is a conditional handover, the conditional handover configuration sent by the target gNB-CU-CP to the UE may carry the indication information of whether the target base station supports PDU collective processing. In the conditional handover, the source base station prepares multiple target base stations, and each target base station includes the indication information of whether the base station supports PDU collective processing in the RRC message sent to the UE. After the UE receives the conditional handover configuration, the UE can refer to the information of whether the candidate base station supports PDU collective processing to decide which candidate base station to select as the target base station.

[0186] In step 505, the first node sends a bearer context modification request message to a source user plane entity (for example, a source gNB-CU-UP. The following description uses the source gNB-CU-UP as an example, but it can be understood that the source user plane entity may also be a source gNB-DU).

[0187] The first node (i.e., the source gNB-CU-CP) sends a bearer context modification request message to the source gNB-CU-UP, where the message includes the identifier of the UE on the E1 interface, the session identifier for data forwarding, and data forwarding information. The data forwarding information includes the transport layer address and tunnel identifier for uplink and / or downlink data forwarding, and the identifier of the QoS flow for data forwarding.

[0188] When the source gNB-CU-CP learns from the saved UE context that the UE is performing XR services, and the received handover response does not contain the indication information that the target base station supports XR services, as described above, the indication information can be implicitly indicated by including the indication information of XR QoS parameter acceptance in the message, or through an explicit indication information, then the source gNB-CU-CP can know that the target base station does not support PDU set processing. At this time, the data forwarding to the target gNB-CU-CP can not include XR related information in the GTP header. In the message that the source gNB-CU-CP sends the bearer context modification request message to the source user plane entity, it can indicate that the target base station does not support XR, or indicate that data forwarding does not need to add XR related information.

[0189] Step 506: The source user plane entity sends a bearer context modification request message to the first node.

[0190] The message contains the UE's E1 interface identifier, a list of successfully modified PDU sessions, including session identifiers, data radio bearer identifiers, and PDCP sequence number status information. The PDCP sequence number status information contains the status of the received PDCP SDU, uplink COUNT value, and downlink COUNT value. The COUNT value contains the PDCP SN and hyperframe number (HFN number).

[0191] Step 507: The source gNB-CU-CP sends a handover command to the UE, and the handover command is sent to the UE via an RRC reconfiguration request.

[0192] The source gNB-CU-CP sends the handover command sent by the target gNB-CU-CP to the UE.

[0193] For conditional switching, the conditional switching configuration sent by the target gNB-CU-CP to the UE may also carry indication information on whether the target base station supports PDU collective processing. In conditional switching, the source base station prepares multiple target gNB-CU-CPs, and each target base station includes the indication information on whether the base station supports PDU collective processing in the RRC message sent to the UE. After the UE receives the conditional switching configuration, the UE can refer to the information on whether the candidate gNB-CU-CP supports PDU collective processing to decide which candidate base station to select as the target base station.

[0194] Step 508: The source gNB-CU-CP (i.e., the first node) sends an SN status transfer message to the target gNB-CU-CP (i.e., the second node).

[0195] During a normal handover, the source gNB-CU-CP can suspend data transmission and reception, stop allocating PDCP (Packet Data Convergence Protocol) sequence numbers to downlink service data units (SDUs), and stop sending uplink SDUs to the core network.

[0196] The message in step 508 carries the identifier of the DRB and the PDCP sequence number status information of the DRB, which includes the uplink count value (COUNT value) and the downlink COUNT value. After receiving the value, the destination base station assigns the PDCP sequence number included in the DL COUNT value to the first downlink data packet that has not been assigned a PDCP sequence number. If the source base station accepts the uplink data forwarding requested by the destination base station, the message may also include the reception status of the lost or received uplink SDU.

[0197] In step 509, the second node (i.e., the target gNB-CU-CP) sends a bearer context modification request message to the user plane entity (i.e., the target gNB-CU-UP).

[0198] The target gNB-CU-CP sends a bearer context modification request message to the target gNB-CU-UP. The message includes the UE identifier on the E1 interface, the session identifier and / or DRB identifier for data forwarding, and the PDCP sequence number status information corresponding to the DRB.

[0199] In step 510, the user plane entity (i.e., the target gNB-CU-UP) sends a bearer context modification response message to the second node (i.e., the target gNB-CU-CP).

[0200] The target gNB-CU-UP sends a bearer context modification response message to the target gNB-CU-CP. The message includes the UE identifier on the E1 interface and may also include indication information on whether the target gNB-CU-UP supports XR services at this step.

[0201] Step 511: The UE synchronizes with the target cell and sends a handover completion message to the target gNB-CU-CP.

[0202] If it is a conditional handover, when selecting the target cell, the UE can refer to whether the target cell / target gNB-CU-CP supports PDU aggregate processing. When the UE has ongoing PDU aggregate processing, it can select the gNB-CU-CP that supports PDU aggregate processing as the target gNB-CU-CP if the conditional handover is met.

[0203] Step 512: The target gNB-CU-CP sends a path switching request message to the core network AMF.

[0204] The path switch request message contains the UE location information and the PDU session list switched to the target gNB-CU-CP. The UE location information contains the unique identifier of the cell where the UE is located and the tracking area identifier where the UE is located. The specific information of the PDU session switched to the target gNB-CU-CP is contained in the N2 SM container, which contains the user plane address and QoS flow information.

[0205] If the target base station supports PDU set processing, the message also includes indication information that the target base station supports PDU set processing. The indication information can indicate that the QoS information corresponding to a PDU set in the QoS flow has been accepted, for example, indicating that the PSBD has been accepted, or the indication information is an explicit indication information, indicating that the target base station supports PDU set processing. Not including the indication information means that the target base station does not support it, or indicates that the target base station supports or does not support PDU set processing. The target base station supports it, which means that gNB-CU-CP, gNB-CU-UP, and gNB-DU all support PDU set processing.

[0206] If the target base station does not support PDU aggregate processing, the message does not contain any XR-related indication information, or contains indication information indicating that the base station does not support PDU aggregate processing. If the target base station does not support it, it means that one of gNB-CU-CP, gNB-CU-UP, or gNB-DU does not support PDU aggregate processing.

[0207] The indication information in the above step can be sent from the target gNB-CU-CP to the SMF through the N2 SM container, or included outside the SM container and sent to the AMF, and then the AMF sends it to the SMF through step 307.

[0208] Step 513: AMF sends a path switch response message to the target gNB-CU-CP.

[0209] The AMF sends a response message to the target gNB-CU-CP. The message includes the N2SM container received from the SMF.

[0210] The path switching response message contains the UE's identification on the NG interface, the bearer information of the successful switching or the identification of the PDUSession, and the N2 SM container. The N2 SM container contains the content configured by the SMF and is transparent to the AMF. The container contains the information of the user plane allocated by the UPF and the QoS information.

[0211] Step 514: The target gNB-CU-CP sends a UE context release request message to the source gNB-CU-CP.

[0212] After the UE switches to the target gNB-CU-CP, the target gNB-CU-CP can send a UE context release request message to request the source gNB-CU-CP to release the stored UE related information and resources.

[0213] So far, the switching process of the above embodiment is completed.

[0214] Through the above embodiments, the UE can move between the NG-RAN that supports PDU sets and the NG-RAN that does not support PDU sets, and can dynamically start the QoS parameter configuration and user plane information transmission of the data set, thereby improving the transmission performance of XR service data and meeting the needs of XR services.

[0215] Please refer to Figure 7 , Figure 7 It is a schematic diagram for describing another process of a user equipment UE moving from a first node to a second node according to various embodiments of the present disclosure. Among them, the first node (i.e., the source base station serving the UE) does not support the XR service, that is, the XR service is transmitted as a normal service at the source base station. In this embodiment, the UE moves to the second node, i.e., the destination base station, and the destination base station may or may not support the XR service. The first node and the second node are separate base station structures.

[0216] The specific process of the embodiment of the present disclosure is as follows: Figure 7 As shown. Figure 7 As shown, the method of this embodiment may include one or more steps from step S601 to step S614.

[0217] Step 601: The first node sends a switching request message to the second node.

[0218] The first node is the centralized control entity of the source base station (e.g., the source gNB-CU-CP). Based on the UE measurement results, it decides to switch the UE to the second node. The second node is the centralized control entity of the target base station (e.g., the target gNB-CU-CP). The switching request message includes one or more of the following: the identifier of the target cell, the list of PDU sessions in progress of the UE, the PDU session list includes the PDU session identifier (PDU session ID), the QoS flow identifier (QoS flow ID), the service quality requirements of the QoS flow, and the uplink data receiving address, such as the transport layer IP address and the tunnel identifier TEID. This information is allocated by the core network user plane node UPF. The message also includes information about data forwarding from the first node. The data forwarding information includes a recommendation for data forwarding for the uplink data and / or downlink data of a certain session or a certain DRB.

[0219] For XR services, the source gNB-CU-CP treats XR services as ordinary services. Therefore, the handover request message does not contain XR-specific information.

[0220] Step 602: The second node sends a bearer context establishment request message to a destination user plane entity.

[0221] The target user plane entity may be a target gNB-CU-UP. The following description is made by taking the second node being the target gNB-CU-CP and the target user plane entity being the target gNB-CU-UP as an example. The target gNB-CU-CP sends a bearer context establishment request message to the target gNB-CU-UP. The message includes the identifier of the UE on the E1 interface, encryption information, the service operator identifier PLMN ID, the identifier of the UE on the access network RAN ​​ID, the identifier of the base station separation unit DU, and the PDU session list to be established. The PDU session list includes the PDU session identifier, S-NSSAI, encryption indication, uplink transport layer address, such as IP address and TEID. This information is allocated by the core network user plane node UPF to receive uplink data. The PDU session list also includes a DRB list to be established. The DRB list includes a DRB identifier, a quality of service (QoS) of the DRB, SDAP configuration, PDCP configuration, PDCP sequence number status information, Cell group information, and a QoS flow list to be established. The gNB-CU-CP determines the mapping of the QoS flow to the data radio channel. The QoS flow list includes the QoS flow identifier, the quality of service QoS of the QoS flow, etc.

[0222] The bearer context establishment request message does not contain XR-specific information.

[0223] Step 603: The target gNB-CU-UP sends a bearer establishment response message to the target gNB-CU-CP (i.e., the second node).

[0224] The target gNB-CU-UP sends a bearer context establishment response message to the target gNB-CU-CP. The message contains the UE's E1 interface identifier, the successfully established PDU session list, the PDU session list contains the PDU session identifier, the encryption result, and the downlink transport layer address, which is allocated by the gNB-CU-UP and is used to receive downlink data sent by the core network. The message also contains the successfully established DRB list, which contains the DRB identifier, DRB data forwarding information, and the uplink user plane information of the DRB. The uplink user plane information contains the user plane transport layer address, cell group identifier, and other information. The uplink user plane address is allocated by the gNB-CU-CP and is used to receive uplink data sent by the DU.

[0225] If the target gNB-CU-UP supports PDU set processing, the message in step 603 includes indication information that the target gNB-CU-UP supports PDU set processing. The indication information is an explicit indication information, indicating that the target gNB-CU-UP supports PDU set processing. Not including the indication information means that the target gNB-CU-UP does not support it, or indicates that the target gNB-CU-UP supports or does not support PDU set processing.

[0226] The target gNB-CU-UP can know whether conditional switching is performed from the CHO indication included in the bearer context establishment request message. If it is a conditional switching, the target gNB-CU-UP response message can also carry indication information on whether the target gNB-CU-UP supports PDU set processing. It is sent by the second node to the UE through the first node. In conditional switching, the first node prepares multiple target base stations, and each target base station includes the indication information on whether the base station supports PDU set processing in the RRC message sent to the UE. After the UE receives the conditional switching configuration, the UE can refer to the information on whether the candidate base station supports PDU set processing to decide which candidate base station to select as the target base station.

[0227] The process between the target gNB-CU-CP and the target gNB-DU is omitted here. Similarly, the gNB-DU can include the XR QoS parameter acceptance indication information in the UE context establishment response message to implicitly indicate that the gNB-DU supports the PDU set, or through an explicit indication information, indicate that the gNB-DU supports the PDU set and / or does not support the PDU set. The XR QoS parameter acceptance indication information can indicate that the QoS corresponding to the PDU set of a certain XR service is accepted.

[0228] Step 604: The second node sends a switching response message to the first node.

[0229] The target gNB-CU-CP establishes resources corresponding to the session based on the session related information contained in the handover request message. The session related information includes the session identifier, the session includes the QoS flow information, and the data forwarding suggestion. Based on the forwarding suggestion, the target gNB-CU-CP decides whether data forwarding is required for the session and / or for the DRB. If data forwarding is required, the target base station allocates a data forwarding address for the session or DRB.

[0230] The target gNB-CU-CP sends a handover response message to the source gNB-CU-CP. The message carries the UE's identifier on the Xn interface, the bearer information or PDU session information received at the target gNB-CU-CP, data forwarding information, and a handover command message to be sent to the UE. The data forwarding information includes the identifier of the QoS flow to which data is to be forwarded, the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the PDU session, and may also include the identifier of the DRB to which data is to be forwarded, and the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the DRB.

[0231] If it is a conditional handover, the conditional handover configuration sent by the target gNB-CU-CP to the UE may carry the indication information of whether the target gNB-CU-CP supports PDU collective processing. In the conditional handover, the source base station prepares multiple target base stations, and each target base station includes the indication information of whether the base station supports PDU collective processing in the RRC message sent to the UE. After the UE receives the conditional handover configuration, the UE can refer to the information of whether the candidate base station supports PDU collective processing to decide which candidate base station to select as the target base station.

[0232] Step 605: The first node sends a bearer context modification request message to the source user plane entity (e.g., source gNB-CU-CP).

[0233] The source gNB-CU-CP sends a bearer context modification request message to the source gNB-CU-UP. The message includes the UE identifier on the E1 interface, the session identifier for data forwarding, and data forwarding information. The data forwarding information includes the transport layer address and tunnel identifier for uplink and / or downlink data forwarding, and the identifier of the QoS flow for data forwarding.

[0234] Step 606: The source user plane entity sends a bearer context modification request message to the first node.

[0235] The message contains the UE's E1 interface identifier, a list of successfully modified PDU sessions, including session identifiers, data radio bearer identifiers, and PDCP sequence number status information. The PDCP sequence number status information contains the status of the received PDCP SDU, uplink COUNT value, and downlink COUNT value. The COUNT value contains the PDCP SN and hyperframe number (HFN number).

[0236] Step 607: The source gNB-CU-CP sends a handover command to the UE, and the handover command is sent to the UE via an RRC reconfiguration request.

[0237] The source gNB-CU-CP sends the handover command sent by the target gNB-CU-CP to the UE.

[0238] For conditional switching, the conditional switching configuration sent by the target gNB-CU-CP to the UE may also carry indication information on whether the target base station supports PDU collective processing. In conditional switching, the source base station prepares multiple target base stations, and each target base station includes the indication information on whether the base station supports PDU collective processing in the RRC message sent to the UE. After the UE receives the conditional switching configuration, the UE can refer to the information on whether the candidate base station supports PDU collective processing to decide which candidate base station to select as the target base station.

[0239] Step 608: The source gNB-CU-CP sends an SN status transfer message to the target gNB-CU-CP.

[0240] During a normal handover, the source gNB-CU-CP can suspend data transmission and reception, stop allocating PDCP (Packet Data Convergence Protocol) sequence numbers to downlink service data units (SDUs), and stop sending uplink SDUs to the core network.

[0241] The message of step 608 carries the identifier of the DRB and the PDCP sequence number status information of the DRB, which includes the uplink count value (COUNT value) and the downlink COUNT value. After receiving the value, the target gNB-CU-CP assigns the PDCP sequence number included in the DL COUNT value to the first downlink data packet that has not been assigned a PDCP sequence number. If the source base station accepts the uplink data forwarding requested by the target base station, the message may also include the reception status of the lost or received uplink SDU.

[0242] Step 609: The second node sends a bearer context modification request message to the target user plane entity (e.g., the target gNB-CU-UP).

[0243] The target gNB-CU-CP sends a bearer context modification request message to the target gNB-CU-UP. The message includes the UE identifier on the E1 interface, the session identifier and / or DRB identifier for data forwarding, and the PDCP sequence number status information corresponding to the DRB.

[0244] Step 610: The destination user plane entity sends a bearer context modification response message to the second node.

[0245] The target gNB-CU-UP sends a bearer context modification response message to the target gNB-CU-CP. The message includes the identifier of the UE on the E1 interface. In this step, if the target gNB-CU-UP supports PDU set processing, the message in step 603 includes indication information that the target gNB-CU-UP supports PDU set processing. The indication information is an explicit indication information, indicating that the target gNB-CU-UP supports PDU set processing. The absence of this indication information means that the target gNB-CU-UP does not support it, or indicates that the target gNB-CU-UP supports or does not support PDU set processing.

[0246] Step 611: The UE synchronizes with the target cell and sends a handover completion message to the target gNB-CU-CP.

[0247] If it is a conditional switching, when selecting the destination cell, the UE can refer to whether the destination cell / destination base station supports PDU collective processing. When the UE has an ongoing XR service, it can select a base station that supports PDU collective processing as the destination base station on the premise that the conditional switching is met.

[0248] Step 612: The target gNB-CU-CP sends a path switching request message to the core network AMF.

[0249] The path switch request message contains the UE's location information and the PDU session list switched to the target base station. The UE's location information contains the unique identifier of the cell where the UE is located and the tracking area identifier where the UE is located. The specific information of the PDU session switched to the target base station is contained in the N2 SM container, which contains the user plane address and QoS flow information.

[0250] If the target base station supports PDU collective processing, the target base station supports it, which means that gNB-CU-CP, gNB-CU-UP, and gNB-DU all support PDU collective processing. The message also includes indication information that the target base station supports PDU collective processing. The indication information is an explicit indication information, indicating that the target base station supports PDU collective processing. Not including this indication information means that the target base station does not support it, or indicates that the target base station supports or does not support PDU collective processing.

[0251] If the target base station does not support PDU aggregation processing, which means that one of the gNB-CU-CP, gNB-CU-UP, and gNB-DU does not support PDU aggregation processing, the message does not contain the indication information of PDU aggregation, or contains indication information indicating that the base station does not support PDU aggregation processing.

[0252] The indication information in the above step can be sent from the base station to the SMF through the N2 SM container, or included outside the SM container and sent to the AMF, and then the AMF sends it to the SMF through step 307.

[0253] Step 613: AMF sends a path switch response message to the target gNB-CU-CP.

[0254] AMF sends a response message to the target gNB-CU-CP. The message includes the N2SM container received from SMF. That is, before sending the path switching message, AMF sends a message to SMF, as described in steps 407 to 410. When SMF knows that the target base station supports PDU set processing, while the source base station does not support PDU set processing, SMF can include PDU set related configuration information in the N2 SM container sent to AMF. The related configuration information includes the QoS flow identifier of the XR service, the period of the XR data transmitted on the QoS flow, the data burst arrival time, the data survival time, the jitter configuration, etc. The related configuration information also includes the QoS parameter configuration of the packet data unit set of the XR service, that is, it includes at least one of the following information: QoS flow ID, the type of PDU set, the identifier of the PDU set, PSDB, PDER, PSIHI. In this way, the target gNB-CU-CP can obtain the unique configuration information of XR as soon as possible, and can schedule and process data according to the characteristics of XR as soon as possible, improve the performance of the XR service, and improve the customer satisfaction of the XR service.

[0255] It is also possible to modify the relevant configuration information of the PDU set later through a separate session modification process, such as through a PDU session modification request message. In a separate process later, the SMF sends the jitter configuration of the XR service and the QoS parameter configuration of the packet data unit set of the XR service to the target gNB-CU-CP through the AMF.

[0256] The path switching response message contains the UE's identification on the NG interface, the bearer information of the successful switching or the identification of the PDUSession, and the N2 SM container. The N2 SM container contains the content configured by the SMF and is transparent to the AMF. The container contains the information of the user plane allocated by the UPF and the QoS information.

[0257] Step 614: The target gNB-CU-CP sends a UE context release request message to the source gNB-CU-CP.

[0258] After the UE switches to the target gNB-CU-CP, the target gNB-CU-CP can send a UE context release request message to request the source gNB-CU-CP to release the stored UE related information and resources.

[0259] So far, the switching process of the above embodiment is completed.

[0260] Through the above embodiments, the UE can move between the NG-RAN that supports PDU sets and the NG-RAN that does not support PDU sets, and can dynamically start the QoS parameter configuration and user plane information transmission of the data set, thereby improving the transmission performance of XR service data and meeting the needs of XR services.

[0261] Please refer to Figure 8 , Figure 8 It is a schematic diagram for describing the Xn process based on the movement of a user equipment UE from a first node to a second node according to various embodiments of the present disclosure. Among them, the first node is also the source base station serving the UE. The UE is configured with a session of the XR service at the source base station and is receiving the XR service. The UE moves to the second node, that is, the destination base station. The first node and the second node are centralized base station structures. This embodiment provides how to provide an enhanced switching process for the XR service.

[0262] The specific process of the embodiment of the present disclosure is as follows: Figure 8 As shown. Figure 8 As shown, the method of this embodiment may include one or more steps from step S701 to step S711.

[0263] Step 701: The first node sends a switching request message to the second node.

[0264] The first node is the source base station. The source base station decides to switch the UE to the second node (destination base station) based on the UE measurement results. The switching request message contains one or more of the following: the identifier of the destination cell, the list of PDU sessions in progress by the UE, the PDU session list contains the PDU session identifier (PDU session ID), the QoS flow identifier (QoS flow ID), the service quality requirements of the QoS flow, and the uplink data receiving address, such as the transport layer IP address and the tunnel identifier TEID. This information is allocated by the core network user plane node UPF. The message also contains information about data forwarding from the source base station. The data forwarding information includes recommendations for data forwarding for uplink data and / or downlink data of a certain session or a certain DRB.

[0265] For XR services, the switching request message also includes the period of XR data transmitted on the QoS flow, data burst arrival time, data survival time, jitter configuration, etc. The switching request also includes the QoS parameter configuration of the packet data unit set of the XR service, that is, it includes at least one of the following information: QoS flow ID, type of PDU set, identifier of PDU set, PSDB, PDER, PSIHI.

[0266] When the first node initiates a handover request, the first node is sending a certain PDU set to the UE, and has not yet sent all the PDUs included in the entire PDU set to the UE. The first node has only transmitted part of the PDUs that have been received, for example, the first N PDUs in the PDU set M, and the first node finds that one or more PDUs are lost in the first N PDUs. The reason for the loss may be that the data is lost in the process of the core network sending data to the first node, or the first node is lost in the process of sending data to the UE at the air interface. If the QoS parameter configuration of the packet data unit set includes PSIHI, and PSIHI is set to "yes", that is, PSIHI indicates that the application layer needs all PDUs in the PDU set to use the PDU set, then the first node includes a PDU set sequence number in the handover request message, and the PDU set sequence number is the sequence number of the PDU set that has not been completely received, or the sequence number of the PDU set that needs to be discarded, such as PSSN M, or indication information and PSSN, the indication information indicates that the data packet in the PDU set M is lost, or indicates that the PDU of the PDU set M is discarded, and M is a natural number greater than 0. When the second node receives the information, the second node receives a GTP-U data packet from the core network. From the PSSN included in the data packet header, it can be known which PDU set the received PDU belongs to. If the second node receives a PDU of the PDU set M, all received PDUs belonging to the PDU set M are discarded.

[0267] Another implementation method is for the second node to notify the core network UPF that there is a PDU loss in PDU set M, and to notify UPF that it is not necessary to send all PDUs belonging to PDU M. These methods are all performed under the premise that PSIHI indicates that the application layer needs all PDUs of the PDU set using the PDU set, and method 1 and method 2 can be used in combination.

[0268] When the first node forwards data, if it learns that a PDU in the PDU set M is lost, the first node does not forward the PDUs in the set M that have not been transmitted to the UE. It only forwards the PDUs that have not been lost and have not been transmitted to the UE to the second node.

[0269] Step 702: The second node sends a switching response message to the first node.

[0270] The second node (i.e., the destination base station) establishes resources corresponding to the session based on the session related information contained in the handover request message. The session related information includes the session identifier, the session includes the QoS flow information, and the data forwarding suggestion. Based on the forwarding suggestion, the destination base station decides whether data forwarding is required for the session and / or for the DRB. If data forwarding is required, the destination base station allocates a data forwarding address for the session or DRB.

[0271] The destination base station sends a switching response message to the source base station. The message carries the UE's identifier on the Xn interface, the bearer information or PDU session information received at the destination base station, data forwarding information, and a switching command message to be sent to the UE. The data forwarding information includes the identifier of the QoS flow to which data is to be forwarded, the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the PDU session, and may also include the identifier of the DRB to which data is to be forwarded, and the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the DRB. The data forwarding address is allocated by the destination base station.

[0272] Step 703: The source base station sends a handover command to the UE.

[0273] The source base station sends the handover command sent by the target base station to the UE via an RRC reconfiguration request message.

[0274] Step 704: The first node sends an SN status transmission message to the second node.

[0275] The SN status transmission message is when the source needs to forward data to the destination, and the source base station needs to send the transmission status of the data on the source base station to the destination base station through the SN status transmission message. If there is no data forwarding, the SN status transmission message in step 704 can be a new message.

[0276] During a normal handover process, the source base station may suspend data transmission and reception, stop allocating PDCP (Packet Data Convergence Protocol) sequence numbers to downlink service data units SDU (Protocol Data Unit), and stop sending uplink SDUs to the core network.

[0277] The SN status transmission message carries the DRB identifier, the uplink count value (COUNT value) and / or downlink COUNT value of the DRB. After receiving the value, the destination base station assigns the PDCP sequence number contained in the DL COUNT value to the first downlink data packet that has not been assigned a PDCP sequence number. The message may also include the reception status of the lost or received uplink SDU.

[0278] When the first node initiates an SN status transmission message or a new message, the first node is sending a PDU set to the UE, and has not yet sent all the PDUs contained in the entire PDU set to the UE. The first node has only transmitted part of the received PDUs, for example, the first N PDUs in the PDU set M, and the first node finds that one or more PDUs are lost in the first N PDUs. The reason for the loss may be that the data is lost in the process of the core network sending the data to the first node, or the data is lost in the process of the first node sending the data to the UE over the air interface. If the QoS parameter configuration of the packet data unit set includes PSIHI, and PSIHI is set to "yes", that is, PSIHI indicates that the application layer needs all PDUs in the PDU set to use the PDU set, then the first node includes the PDU set sequence number in the SN status transmission message or the new message, and the PDU set sequence number is the sequence number of the PDU set that has not been completely received, or the sequence number of the PDU set that needs to be discarded, such as PSSN M, or indication information and PSSN, the indication information indicates that data packets in PDU set M are lost, or indicates to discard PDUs of PDU set M, where M is a natural number greater than 0.

[0279] There are two implementation methods here. Method 1 is that the second node discards the PDU belonging to PDU set M. When the second node receives a GTP-U data packet from the core network, it can know the PDU set to which the received PDU belongs from the PSSN contained in the data packet header. If the second node receives the PDU of the PDU set M, it discards all received PDUs belonging to PDU set M. Method 2 is that the second node notifies the core network UPF that there is a PDU loss in PDU set M, and notifies UPF that it does not need to send all PDUs belonging to PDU M. These methods are all performed under the premise that PSIHI indicates that the application layer needs all PDUs of the PDU set to use the PDU set. Method 1 and Method 2 can be used in combination.

[0280] When the first node forwards data, if it learns that a PDU in the PDU set M is lost, the first node does not forward the PDUs in the set M that have not been transmitted to the UE. It only forwards the PDUs that have not been lost and have not been transmitted to the UE to the second node.

[0281] Step 705: The UE synchronizes with the target cell and sends a handover completion message to the second node.

[0282] Step 706: The second node sends a path switching request message to the core network AMF.

[0283] The path switch request message contains the UE's location information and the PDU session list switched to the destination base station. The UE's location information contains the unique identifier of the cell where the UE is located and the tracking area identifier where the UE is located. The specific information of the PDU session switched to the destination base station is contained in the SM container, which is sent to the SMF, and the AMF transparently forwards it to the SMF. The SM container contains the user plane address assigned by the destination base station, which is used to receive downlink data packets, and contains the list of accepted QoS flows.

[0284] According to the above method 2, the path switching request message includes a PDU set sequence number, which is the sequence number of the PDU set that has not been completely received, or the sequence number of the PDU set that needs to be discarded, such as PSSN M, or indication information and PSSN. The discarded PSSN M, or indication information and PSSN are obtained from the first node in step 701 or in step 704. The sequence number of the PDU set or the indication information and PSSN may be included in the SM container or outside the SM container. The indication information indicates that a data packet in the PDU set M is lost, or indicates that the PDU of the PDU set M is discarded. The AMF forwards the sequence number of the PDU set, such as PSSN M, or the indication information and PSSN to the SMF, and the SMF forwards the PSSN M, or the indication information and PSSN to the UPF.

[0285] Step 707: AMF sends a session modification request message to SMF.

[0286] The AMF sends a message to the SMF, which carries the above SM container. The information in the container is parsed and saved by the SMF. The message may also include the location information of the UE. Or the message may also include indication information that the destination base station supports XR.

[0287] According to the above method 2, the session modification request message includes a PDU set sequence number, which is the sequence number of the PDU set that has not been completely received, or the sequence number of the PDU set that needs to be discarded, such as PSSN M, or indication information and PSSN, PSSN M and indication information can be included in the SM container, or included outside the container. The indication information indicates that the data packet in PDU set M is lost, or indicates to discard the PDU of PDU set M.

[0288] Step 708: SMF sends a session modification request message to UPF.

[0289] SMF sends a session modification request message to UPF. The message contains the downlink data receiving address assigned by the destination base station. UPF knows that the UE has switched to a new base station and will send the data to the new base station.

[0290] According to the above method 2, the session modification request message contains a PDU set sequence number, which is the sequence number of the PDU set that has not been completely received, or the sequence number of the PDU set that needs to be discarded, such as PSSN M, or indication information and PSSN. When UPF receives PSSN M, or indication information and PSSN information, UPF may not send all PDUs belonging to PSSN M to the new base station (or new gNB-CU-UP, or target base station, or target gNB-CU-UP, the same below), or when UPF sends data to the new base station, it starts from a complete PDU set, for example, the data of PSSN M is sent through the source base station, and starting from a new complete PDU set data, UPF sends data to the target base station. In this way, all PDUs contained in the PSSN M are sent to the source base station, and the source base station can decide to discard the remaining data of PSSN M according to the situation, or forward the data of PSSN M to the target base station, and the target base station continues to send it to the UE. After sending all PDUs of PSSN M to the source base station and adding an end marker, UPF starts sending data to the destination base station from a completed PDU set.

[0291] Step 709: UPF sends a session modification response message to SMF.

[0292] UPF sends a response message to SMF. The message may include the receiving address of the uplink data allocated by UPF.

[0293] Step 710: SMF sends a session modification response message to AMF.

[0294] SMF sends a response message to AMF. The message may contain an SM container, which contains the uplink data receiving address allocated by UPF. The data receiving address contains the transport layer IP address and GTP tunnel identifier. The container also contains information about the received QoS flow, including alternative QoS parameters for the QoS flow.

[0295] Step 711: AMF sends a path switch response message to the second node.

[0296] The AMF sends a response message to the target base station, which includes the SM container received in step 710.

[0297] The path switching response message contains the UE's identification on the NG interface, the bearer information of the successful switching or the identification of the PDUSession, and the SM container. The SM container contains the content configured by the SMF and is transparent to the AMF. The container contains the information of the user plane allocated by the UPF and the information of the QoS flow.

[0298] Step 712: The second node sends a UE context release request message to the first node.

[0299] After the UE is switched to the target base station, the target base station may send a UE context release request message to request the source base station to release the stored relevant information and resources of the UE.

[0300] So far, the switching process of the above embodiment is completed.

[0301] Through the above embodiments, when the UE moves, the sending of XR data can be reduced, the resources of the air interface can be saved, and the transmission efficiency of the XR data can be improved.

[0302] Please refer to Fig. 9 , Fig. 9 It is a schematic diagram for describing another process based on Xn for a user equipment UE to move from a first node to a second node according to various embodiments of the present disclosure. The first node is also a source base station serving the UE. The UE is configured with a session of an XR service at the source base station and is receiving the XR service. The UE moves to the second node, i.e., the destination base station. The first node and the second node are separate base station structures. This embodiment provides how to provide an enhanced switching process for the XR service.

[0303] The specific process of the embodiment of the present disclosure is as follows: Fig. 9 As shown. Fig. 9 As shown, the method of this embodiment may include one or more steps from step S801 to step S814.

[0304] Step 801: A first node sends a switching request message to a second node.

[0305] The first node is the centralized control entity of the source base station (e.g., the source gNB-CU-CP), and the second node is the centralized control entity of the target base station (e.g., the target gNB-CU-CP). The source gNB-CU-CP decides to switch the UE to the target gNB-CU-CP based on the UE measurement result. The handover request message includes one or more of the following: the identifier of the target cell, the list of PDU sessions in progress of the UE, the PDU session list includes the PDU session identifier (PDU session ID), the QoS flow identifier (QoS flow ID), the service quality requirements of the QoS flow, and the uplink data receiving address, such as the transport layer IP address and the tunnel identifier TEID, which is allocated by the core network user plane node UPF. The message also includes the source gNB-CU-CP's information on data forwarding, and the data forwarding information includes the recommendation for data forwarding of the uplink data and / or downlink data of a certain session or a certain DRB.

[0306] For XR services, the switching request message also includes the period of XR data transmitted on the QoS flow, data burst arrival time, data survival time, jitter configuration, etc. The switching request also includes the QoS parameter configuration of the packet data unit set of the XR service, that is, it includes at least one of the following information: QoS flow ID, type of PDU set, identifier of PDU set, PSDB, PDER, PSIHI.

[0307] Step 802: The second node sends a bearer context establishment request message to a user plane entity.

[0308] The user plane entity may be the target gNB-CU-UP. The following description is made by taking the second node being the target gNB-CU-CP and the user plane entity being the target gNB-CU-UP as an example. The target gNB-CU-CP sends a bearer context establishment request message to the target gNB-CU-UP. The message includes the identifier of the UE on the E1 interface, encryption information, the service operator identifier PLMN ID, the identifier of the UE on the access network RAN ​​ID, the identifier of the base station separation unit DU, and the PDU session list to be established. The PDU session list includes the PDU session identifier, S-NSSAI, encryption indication, uplink transport layer address, such as IP address and TEID. This information is allocated by the core network user plane node UPF to receive uplink data. The PDU session list also includes a DRB list to be established. The DRB list includes a DRB identifier, a quality of service (QoS) of the DRB, SDAP configuration, PDCP configuration, PDCP sequence number status information, Cell group information, and a QoS flow list to be established. The gNB-CU-CP determines the mapping of the QoS flow to the data radio channel. The QoS flow list includes the QoS flow identifier, the quality of service QoS of the QoS flow, etc.

[0309] For XR services, the bearer context establishment request message also includes the period of XR data transmitted on the QoS flow, data burst arrival time, data survival time, jitter configuration, etc. The switching request also includes the QoS parameter configuration of the packet data unit set of the XR service, that is, it includes at least one of the following information: QoS flow ID, type of PDU set, identifier of PDU set, PSDB, PDER, PSIHI.

[0310] Step 803: The target gNB-CU-UP sends a bearer establishment response message to the second node.

[0311] The target gNB-CU-UP sends a bearer context establishment response message to the target gNB-CU-CP. The message contains the UE's E1 interface identifier, the successfully established PDU session list, the PDU session list contains the PDU session identifier, the encryption result, and the downlink transport layer address, which is allocated by the target gNB-CU-UP to receive the downlink data sent by the core network. The message also contains the successfully established DRB list, which contains the DRB identifier, DRB data forwarding information, and the uplink user plane information of the DRB. The uplink user plane information contains the user plane transport layer address, cell group identifier and other information. The uplink user plane address is allocated by the target gNB-CU-CP to receive the uplink data sent by the DU. The message may also contain the QoS parameters of the received packet data unit set.

[0312] Step 804: The second node sends a switching response message to the first node.

[0313] The target gNB-CU-CP (i.e., the second node) establishes resources corresponding to the session based on the session related information contained in the handover request message. The session related information includes the session identifier, the session includes the QoS flow information, and the data forwarding suggestion. Based on the forwarding suggestion, the target base station decides whether data forwarding is required for the session and / or for the DRB. If data forwarding is required, the target base station allocates a data forwarding address for the session or DRB.

[0314] The target gNB-CU-CP sends a handover response message to the source gNB-CU-CP. The message carries the UE's identifier on the Xn interface, the bearer information or PDU session information received by the target gNB-CU-CP, data forwarding information, and a handover command message to be sent to the UE. The data forwarding information includes the identifier of the QoS flow to which data is to be forwarded, the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the PDU session, and may also include the identifier of the DRB to which data is to be forwarded, and the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the DRB.

[0315] Step 805: The first node sends a bearer context modification request message to the source user plane entity.

[0316] The source gNB-CU-CP sends a bearer context modification request message to the source gNB-CU-UP, which includes the UE identifier on the E1 interface, the session identifier for data forwarding, and data forwarding information, which includes the transport layer address and tunnel identifier for uplink and / or downlink data forwarding, and the identifier of the QoS flow for data forwarding. The message also includes PDCP SN status request information, which indicates that the source gNB-CU-UP needs to report the status of the PDCP SN in the response message.

[0317] The message in step 805 may also indicate that the first node needs the source gNB-CU-UP to report the status of the PDU set. Upon receiving the indication information, the source gNB-CU-UP needs to send the status of the PDU set to the first node.

[0318] Step 806: The source gNB-CU-UP sends a bearer context modification response message to the first node.

[0319] The message contains the UE's E1 interface identifier, a list of successfully modified PDU sessions, including session identifiers, data radio bearer identifiers, and PDCP sequence number status information. The PDCP sequence number status information contains the status of the received PDCP SDU, uplink COUNT value, and downlink COUNT value. The COUNT value contains the PDCP SN and hyperframe number (HFN number).

[0320] If the message 805 includes PDCP SN status request information, or includes indication information indicating the source user plane to report the status of the PDU set, or the user plane has established a session or QoS flow for the XR service, a certain PDU set is being sent to the UE on the source user plane, and the PDUs contained in the entire PDU set have not yet been sent to the UE, the user plane has only transmitted part of the received PDUs, for example, the first N PDUs in the PDU set M, and the source user plane has found that one or more PDUs are lost in the first N PDUs. The reason for the loss may be that the data is lost in the process of the core network sending data to the source user plane, or the source user plane is lost in the process of sending data to the UE over the air interface. If the QoS parameter configuration of the packet data unit set includes PSIHI, and PSIHI is set to "yes", that is, PSIHI indicates that the application layer needs all PDUs of the PDU set using the PDU set, then the source user plane entity includes a PDU set sequence number in the bearer context modification response message, where the PDU set sequence number is the sequence number of the PDU set that has not been completely received, or the sequence number of the PDU set that needs to be discarded, such as PSSN M, or indication information and PSSN, including indication information, the indication information indicates that a data packet in PDU set M is lost, or indicates to discard PDUs of PDU set M. M is a natural number greater than 0.

[0321] Step 807: The first node sends a handover command to the UE.

[0322] The first node sends the handover command sent by the second node to the UE via an RRC reconfiguration request message.

[0323] Step 808: The first node sends an SN status transmission message to the second node.

[0324] The SN status transmission message is when the source needs to forward data to the destination. The source base station needs to send the data transmission status on the source base station to the destination base station through the SN status transmission message. If there is no data forwarding, the SN status transmission message in step 808 can be a new message.

[0325] During a normal handover process, the source base station may suspend data transmission and reception, stop allocating PDCP (Packet Data Convergence Protocol) sequence numbers to downlink service data units SDU (Protocol Data Unit), and stop sending uplink SDUs to the core network.

[0326] The message in step 808 carries the identifier of the DRB, the uplink count value (COUNT value) and the downlink COUNT value of the DRB. After receiving the value, the destination base station assigns the PDCP sequence number contained in the DL COUNT value to the first downlink data packet that has not been assigned a PDCP sequence number. The message may also include the reception status of the lost or received uplink SDU.

[0327] The SN status transmission message or the new message includes a PDU set sequence number, which is the sequence number of the PDU set that has not been completely received, or the sequence number of the PDU set that needs to be discarded, such as PSSN M, or indication information and PSSN, the indication information indicates that the data packet in PDU set M is lost, or indicates to discard the PDU of PDU set M. M is a natural number greater than 0.

[0328] There are two implementation methods here. Method 1 is that the second node discards the PDU belonging to PDU set M. When the second node receives a GTP-U data packet from the core network, the second node can know the PDU set to which the received PDU belongs from the PSSN contained in the data packet header. If the second node receives the PDU of the PDU set M, all received PDUs belonging to PDU set M are discarded. Method 2 is that the second node notifies the core network UPF that there is a PDU loss in PDU set M, and notifies UPF that it does not need to send all PDUs belonging to PDU M. These methods are all performed under the premise that PSIHI indicates that the application layer needs all PDUs of the PDU set to use the PDU set. Method 1 and Method 2 can be used in combination.

[0329] When the user plane of the source base station forwards data, if the user plane of the source base station learns that a PDU in the PDU set M is lost, the user plane of the source base station does not forward the PDUs in the set M that have not been transmitted to the UE. Only the PDUs that have not been lost and have not been transmitted to the UE are forwarded to the second node.

[0330] According to the above method 1, the second node receives the sequence number M of the PDU set to be discarded, or the indication information and PSSN. If the second node receives a GTP-U data packet from the core network, the PSSN included in the data packet header can be used to know the PDU set to which the received PDU belongs. If the second node receives the PDU of the PDU set M, all received PDUs belonging to the PDU set M are discarded. When the base station is a separated architecture, this method is implemented by the user plane of the second node, and the following steps are performed.

[0331] Step 809: The second node sends a bearer context modification request message to a destination user plane entity.

[0332] The target gNB-CU-CP sends a bearer context modification request message to the target gNB-CU-UP. The message includes the UE identifier on the E1 interface, the session identifier and / or DRB identifier for data forwarding, and the PDCP sequence number status information corresponding to the DRB.

[0333] The bearer context modification request message includes the sequence number M of the PDU set to be discarded, or indication information and PSSN, where the indication information indicates that data packets in the PDU set M are lost, or indicates discarding the PDUs in the PDU set M. M is a natural number greater than 0.

[0334] When the destination gNB-CU-UP receives a GTP-U data packet from the core network, the PDU set to which the received PDU belongs can be known from the PSSN contained in the data packet header. If the destination gNB-CU-UP receives a PDU of the PDU set M, all received PDUs belonging to the PDU set M are discarded.

[0335] Step 810: The destination user plane entity sends a bearer context modification response message to the second node.

[0336] The target gNB-CU-UP sends a Bearer Context Modification Response message to the target gNB-CU-CP, which includes the UE identifier on the E1 interface.

[0337] Step 811: The UE synchronizes with the target cell and sends a handover completion message to the target base station.

[0338] Step 812: The second node sends a path switching request message to the core network AMF.

[0339] The path switch request message includes the location information of the UE and the list of PDU sessions switched to the second node. The location information of the UE includes the unique identifier of the cell where the UE is located and the tracking area identifier where the UE is located. The specific information of the PDU session switched to the second node is contained in the SM container, which includes the address of the user plane allocated by the second node for receiving downlink data packets and the list of accepted QoS flows.

[0340] According to the above method 2, the path switch request message includes a PDU set sequence number, which is the sequence number of the PDU set that has not been completely received, or the sequence number of the PDU set that needs to be discarded, such as PSSN M, or indication information and PSSN, PSSN M, or indication information and PSSN are obtained from the first node in step 808. PSSN M, or indication information and PSSN can be included in the SM container, or included outside the container. The indication information indicates that the data packet in PDU set M is lost, or indicates to discard the PDU of PDU set M.

[0341] As shown in steps 707 to 710, the AMF may send the sequence number of the PDU set, such as PSSN M, or the indication information and PSSN to the UPF. When the UPF receives the PSSN M, or the indication information and PSSN, the UPF may not send all the PDUs belonging to the PSSN M to the new base station (or the new gNB-CU-UP, or the target base station, or the target gNB-CU-UP, the same below), or when the UPF sends data to the new base station, it starts from a complete PDU set. For example, the data of the PSSN M is all sent through the source base station. Starting from the data of a new complete PDU set, the UPF sends data to the target base station. In this way, all the PDUs contained in the PSSN M are sent to the source base station. The source base station may decide to discard the remaining data of the PSSN M according to the situation, or forward the data of the PSSN M to the target base station, and the target base station continues to send it to the UE. After the UPF sends all the PDUs of the PSSN M to the source base station and adds the end mark, the UPF starts to send data to the target base station from a complete PDU set. The process between AMF and UPF is the same as from 707 to 710, and the core network steps are omitted here.

[0342] Step 813: AMF sends a path switch response message to the second node.

[0343] AMF sends a response message to the second party, which includes the SM container received from SMF.

[0344] The path switching response message contains the UE's identification on the NG interface, the bearer information of the successful switching or the identification of the PDUSession, and the SM container. The SM container contains the content configured by the SMF and is transparent to the AMF. The container contains the information of the user plane allocated by the UPF and the QoS information.

[0345] Step 814: The target base station sends a UE context release request message to the source base station.

[0346] After the UE is switched to the target base station, the target base station may send a UE context release request message to request the source base station to release the stored relevant information and resources of the UE.

[0347] So far, the switching process of the above embodiment is completed.

[0348] Through the above embodiments, when the UE moves, the sending of XR data can be reduced, the resources of the air interface can be saved, and the transmission efficiency of the XR data can be improved.

[0349] Please refer to Fig.10 , Fig.10It is a schematic diagram for describing the NG-based process of a user equipment UE moving from a first node to a second node according to various embodiments of the present disclosure. Among them, the first node is also the source base station serving the UE. The UE is configured with a session of an XR service at the source base station and is receiving the XR service. The UE moves to the second node, that is, the destination base station. The first node and the second node are centralized base station structures. This embodiment provides how to provide an enhanced switching process for the XR service.

[0350] The specific process of the embodiment of the present disclosure is as follows: Fig.10 As shown. Fig.10 As shown, the method of this embodiment may include one or more steps from step S901 to step S914.

[0351] Step 901: The first node sends a switching required message to the AMF.

[0352] The source base station decides to switch the UE to the destination base station based on the UE measurement results. The switching request message contains one or more of the following: the identifier of the destination cell, the list of PDU sessions in progress of the UE, the PDU session list contains the PDU session identifier (PDU session ID), the QoS flow identifier (QoS flow ID), the service quality requirements of the QoS flow, and the uplink data receiving address, such as the transport layer IP address and the tunnel identifier TEID. This information is allocated by the core network user plane node UPF. The message also contains the source base station's information about data forwarding. The data forwarding information contains recommendations for data forwarding for uplink data and / or downlink data of a certain session or a certain DRB.

[0353] For XR services, the switching request message also includes the period of XR data transmitted on the QoS flow, data burst arrival time, data survival time, jitter configuration, etc. The switching request also includes the QoS parameter configuration of the packet data unit set of the XR service, that is, it includes at least one of the following information: QoS flow ID, type of PDU set, identifier of PDU set, PSDB, PDER, PSIHI.

[0354] When the first node initiates the handover need, the first node is sending a certain PDU set to the UE, and has not yet sent all the PDUs included in the entire PDU set to the UE. The first node has only transmitted part of the PDUs that have been received, for example, the first N PDUs in the PDU set M, and the first node finds that one or more PDUs are lost in the first N PDUs, and the reason for the loss may be that the data is lost in the process of the core network sending data to the first node, or the first node is lost in the process of sending data to the UE over the air interface. If the QoS parameter configuration of the packet data unit set includes PSIHI, and PSIHI is set to "yes", that is, PSIHI indicates that the application layer needs to use all the PDUs of the PDU set, then the first node includes the sequence number M of the PDU set to be discarded, or the indication information and PSSN in the handover need message, and the indication information indicates that the data packets in the PDU set M are lost, or indicates that the PDUs of the PDU set M are discarded, and M is a natural number greater than 0. The information contained in the switching required message is sent to the second node, i.e., the destination base station, through the AMF. When the second node receives the information, the second node receives a GTP-U data packet from the core network. From the PSSN included in the data packet header, it can be known which PDU set the received PDU belongs to. If the second node receives a PDU of the PDU set M, all received PDUs belonging to the PDU set M are discarded.

[0355] Another implementation method is for the first node or the second node to notify the core network UPF that there is a PDU loss in the PDU set M, and to notify the UPF that it is not necessary to send all PDUs belonging to the PDU M. These methods are all performed under the premise that the PSIHI indicates that the application layer needs all PDUs of the PDU set using the PDU set, and the first method and the second method can be used in combination.

[0356] When the first node forwards data, if it learns that a PDU in the PDU set M is lost, the first node does not forward the PDUs in the set M that have not been transmitted to the UE. It only forwards the PDUs that have not been lost and have not been transmitted to the UE to the second node.

[0357] Step 902: AMF sends a handover request message to the second node.

[0358] The second node is the destination base station. The handover request message contains the source-to-destination transparent container, N2's mobility management information (MM information), N2's session management information (SM information), and the UE radio capability identifier. The source-to-destination transparent container is received from the source base station and forwarded to the destination base station by the AMF. The MM information contains encryption information, mobility restriction list, and other information. The SM information contains session-related information received by the AMF from the SMF.

[0359] Step 903: The second node sends a switching response message to the AMF.

[0360] The message contains the destination to source transparent container, the list of accepted sessions, and the list of unaccepted sessions.

[0361] Step 904: The AMF sends a switching command message to the first node.

[0362] The handover command message contains a transparent container from the destination to the source. The destination base station establishes resources corresponding to the session based on the session related information contained in the handover request message. The session related information includes the session identifier, the session contains QoS flow information, and data forwarding suggestions. Based on the forwarding suggestions, the destination base station decides whether data forwarding is required for the session and / or for the DRB. If data forwarding is required, the destination base station allocates a data forwarding address for the session or DRB.

[0363] The destination base station sends a switching response message to the source base station. The message carries the identifier of the UE on the Xn interface, the bearer information or PDU session information received at the destination base station, data forwarding information, and a switching command message to be sent to the UE. The data forwarding information includes the identifier of the QoS flow for data forwarding, the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the PDU session, and may also include the identifier of the DRB for data forwarding, and the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the DRB. If it is direct data forwarding, the uplink and / or downlink transport layer IP address and GTP tunnel identifier are allocated by the destination base station. If it is indirect data forwarding, the uplink and / or downlink transport layer IP address and GTP tunnel identifier are allocated by the core network.

[0364] Step 905: The first node sends a handover command to the UE.

[0365] The source base station sends the handover command sent by the target base station to the UE. The handover command is sent to the UE via an RRC reconfiguration request message.

[0366] Step 906: The first node sends an uplink RAN ​​status transfer message to the AMF.

[0367] The uplink RAN ​​status transmission message is when data needs to be forwarded from the source to the destination, and the source base station needs to send the data transmission status on the source base station to the destination base station through the RAN status transmission message. If there is no data forwarding, the uplink or downlink RAN ​​status transmission message in steps 906 and 907 can be a new message.

[0368] During a normal handover process, the source base station may suspend data transmission and reception, stop allocating PDCP (Packet Data Convergence Protocol) sequence numbers to downlink service data units SDU (Protocol Data Unit), and stop sending uplink SDUs to the core network.

[0369] The message RAN status transmission transparent container of step 906 carries the identifier of the DRB, the uplink count value (COUNT value) and / or the downlink COUNT value of the DRB. After receiving the value, the destination base station assigns the PDCP sequence number contained in the DL COUNT value to the first downlink data packet that has not been assigned a PDCP sequence number. If the source base station accepts the uplink data forwarding requested by the destination base station, the message may also include the reception status of the lost or received uplink SDU.

[0370] When the first node initiates an uplink RAN ​​status transmission or a new message, a certain PDU set may not be fully transmitted, and only part of the received PDUs is transmitted, for example, the first N PDUs in the PDU set M are transmitted. Moreover, the first node finds that one or more PDUs are lost in the first N PDUs. The reason for the loss may be that the data is lost in the process of the core network sending data to the first node, or lost in the air interface. If the QoS parameter configuration of the packet data unit set includes PSIHI, and PSIHI is set to "yes", that is, PSIHI indicates that the application layer needs all PDUs of the PDU set to use the PDU set, then the first node includes the sequence number M of the PDU set to be discarded, or indication information and PSSN in the uplink RAN ​​status transmission message or the new message, and the indication information indicates that the data packets in the PDU set M are lost, or indicates that the PDUs of the PDU set M are discarded. M is a natural number greater than 0. The information contained in the uplink RAN ​​status message or the new message is sent by the AMF to the second node.

[0371] There are two implementation methods here. Method 1 is that the second node discards the PDU belonging to PDU set M. When the second node receives a GTP-U data packet from the core network, it can know the PDU set to which the received PDU belongs from the PSSN contained in the data packet header. If the second node receives the PDU of the PDU set M, it discards all received PDUs belonging to PDU set M. Method 2 is that the second node notifies the core network UPF that there is a PDU loss in PDU set M, and notifies UPF that it does not need to send all PDUs belonging to PDU M. These methods are all performed under the premise that PSIHI indicates that the application layer needs all PDUs of the PDU set to use the PDU set. Method 1 and Method 2 can be used in combination.

[0372] When the first node forwards data, if it learns that a PDU in the PDU set M is lost, the first node does not forward the PDUs in the set M that have not been transmitted to the UE. It only forwards the PDUs that have not been lost and have not been transmitted to the UE to the second node.

[0373] According to the above-mentioned method 1, the second node receives the sequence number M and / or indication information of the PDU set. If the second node receives a GTP-U data packet from the core network, the PDU set to which the received PDU belongs can be known through the PSSN included in the data packet header. If the second node receives a PDU of the PDU set M, all received PDUs belonging to the PDU set M are discarded.

[0374] Step 907: AMF sends a RAN status transfer message to the second node.

[0375] The message carries the message RAN state transmission transparent container of step 906 .

[0376] Step 908: The UE synchronizes with the target cell and sends a handover completion message to the target base station.

[0377] Step 909: The second node sends a path switching notification message to the core network AMF.

[0378] The path switch notification message contains the UE's location information and the PDU session list switched to the target base station. The UE's location information contains the unique identifier of the cell where the UE is located and the tracking area identifier where the UE is located. The specific information of the PDU session switched to the target base station is contained in the SM container, which contains the address of the user plane and the information of the QoS flow.

[0379] According to the above method 2, the path switching notification message includes the PSSN M to be discarded, or the indication information and the PSSN, and the PSSN M and the indication are obtained from the first node in step 901 or in step 906. The PSSN M and / or the indication information may be included in the SM container or outside the container. The indication information indicates that a data packet in the PDU set M is lost, or indicates that the PDU of the PDU set M is discarded. The AMF forwards the PSSN M and the indication information to the SMF, and the PSSN M and the indication information are forwarded to the UPF.

[0380] Step 910: AMF sends a session modification request message to SMF.

[0381] The AMF sends a message to the SMF, which carries the above-mentioned N2 SM container. The information in the container is parsed and saved by the SMF. The message may also include the location information of the UE. Or the message may also include indication information that the destination base station supports XR.

[0382] According to the above method 2, the session modification request message includes a PDU set sequence number, which is the sequence number of the PDU set that has not been completely received, or the sequence number of the PDU set that needs to be discarded, such as PSSN M, or indication information and PSSN, PSSN M and / or indication information can be included in the SM container, or included outside the container. The indication information indicates that the data packet in PDU set M is lost, or indicates to discard the PDU of PDU set M.

[0383] Step 911: SMF sends a session modification request message to UPF.

[0384] SMF sends a session modification request message to UPF. The message contains the downlink data receiving address assigned by the destination base station. UPF knows that the UE has switched to a new base station and will send the data to the new base station.

[0385] According to the above method 2, the session modification request message contains a PDU set sequence number, which is the sequence number of the PDU set that has not been completely received, or the sequence number of the PDU set that needs to be discarded, such as PSSN M, or indication information and PSSN. When UPF receives PSSN M, or indication information and PSSN, UPF may not send all PDUs belonging to PSSN M to the new base station (or new gNB-CU-UP, or target base station, or target gNB-CU-UP, the same below), or when UPF sends data to the new base station, it starts from a complete PDU set, for example, the data of PSSN M is sent through the source base station, and starting from a new complete PDU set data, UPF sends data to the target base station. In this way, all PDUs contained in the PSSN M are sent to the source base station, and the source base station may decide to discard the remaining data of PSSN M according to the situation, or forward the data of PSSN M to the target base station, and the target base station continues to send it to the UE. After sending all PDUs of PSSN M to the source base station and adding an end marker, UPF starts sending data to the destination base station from a completed PDU set.

[0386] Step 912: UPF sends a session modification response message to SMF.

[0387] UPF sends a response message to SMF. The message may include the receiving address of the uplink data allocated by UPF.

[0388] Step 913: SMF sends a session modification response message to AMF.

[0389] SMF sends a response message to AMF. The message may contain an N2 SM container, which contains the uplink data receiving address allocated by UPF. The data receiving address contains the transport layer IP address and GTP tunnel identifier. The container also contains the received QoS flow information, including alternative QoS parameters for the QoS flow.

[0390] Step 914: The target base station sends a UE context release request message to the source base station.

[0391] After the UE is switched to the target base station, the target base station may send a UE context release request message to request the source base station to release the stored relevant information and resources of the UE.

[0392] So far, the process of the above embodiment is completed.

[0393] Through the above embodiments, when the UE moves, the sending of XR data can be reduced, the resources of the air interface can be saved, and the transmission efficiency of the XR data can be improved.

[0394] Please refer to Fig.11 , Fig.11 It is a schematic diagram for describing another NG-based process of a user equipment UE moving from a first node to a second node according to various embodiments of the present disclosure. The first node is also a source base station serving the UE. The UE is configured with a session for an XR service at the source base station and is receiving the XR service. The UE moves to the second node, which is the destination base station. The first node and the second node are separate base station structures. This embodiment provides how to provide an enhanced switching process for the XR service.

[0395] The specific process of the embodiment of the present disclosure is as follows: Fig.11 As shown. Fig.11 As shown, the method of this embodiment may include one or more steps from step S1001 to step S1016.

[0396] Step 1001: The first node sends a switching required message to the AMF.

[0397] The first node is the centralized control entity of the source base station (e.g., source gNB-CU-CP). The source base station decides to switch the UE to the destination base station based on the UE measurement results. The switching request message contains one or more of the following: the identifier of the destination cell, the list of PDU sessions in progress of the UE, the PDU session list contains the PDU session identifier (PDU session ID), the QoS flow identifier (QoS flow ID), the service quality requirements of the QoS flow, and the uplink data receiving address, such as the transport layer IP address and the tunnel identifier TEID. This information is allocated by the core network user plane node UPF. The message also contains information about data forwarding from the source base station. The data forwarding information contains recommendations for data forwarding for uplink data and / or downlink data of a certain session or a certain DRB.

[0398] For XR services, the switching request message also includes the period of XR data transmitted on the QoS flow, data burst arrival time, data survival time, jitter configuration, etc. The switching request also includes the QoS parameter configuration of the packet data unit set of the XR service, that is, it includes at least one of the following information: QoS flow ID, type of PDU set, identifier of PDU set, PSDB, PDER, PSIHI.

[0399] Step 1002: AMF sends a handover request message to the second node.

[0400] The second node is the centralized control entity of the target base station (e.g., the target gNB-CU-CP). The handover request message contains the source-to-target transparent container, N2's mobility management information (MM information), N2's session management information (SMinformation), and the UE radio capability identifier. The source-to-target transparent container is received from the source gNB-CU-CP and forwarded by the AMF to the target gNB-CU-CP. The MM information contains encryption information, mobility restriction list, and other information. The SM information contains session-related information received by the AMF from the SMF.

[0401] Step 1003: The second node sends a bearer context establishment request message to a destination user plane entity.

[0402] The target user plane entity may be a target gNB-CU-UP. The following description is made by taking the second node being the target gNB-CU-CP and the target user plane entity being the target gNB-CU-UP as an example. The target gNB-CU-CP sends a bearer context establishment request message to the target gNB-CU-UP. The message includes the identifier of the UE on the E1 interface, encryption information, the service operator identifier PLMN ID, the identifier of the UE on the access network RAN ​​ID, the identifier of the base station separation unit DU, and the PDU session list to be established. The PDU session list includes the PDU session identifier, S-NSSAI, encryption indication, uplink transport layer address, such as IP address and TEID. This information is allocated by the core network user plane node UPF to receive uplink data. The PDU session list also includes a DRB list to be established. The DRB list includes a DRB identifier, a quality of service (QoS) of the DRB, SDAP configuration, PDCP configuration, PDCP sequence number status information, Cell group information, and a QoS flow list to be established. The gNB-CU-CP determines the mapping of the QoS flow to the data radio channel. The QoS flow list includes the QoS flow identifier, the quality of service QoS of the QoS flow, etc.

[0403] For XR services, the bearer context establishment request message also includes the period of XR data transmitted on the QoS flow, data burst arrival time, data survival time, jitter configuration, etc. The switching request also includes the QoS parameter configuration of the packet data unit set of the XR service, that is, it includes at least one of the following information: QoS flow ID, type of PDU set, identifier of PDU set, PSDB, PDER, PSIHI.

[0404] Step 1004: The target gNB-CU-UP sends a bearer establishment response message to the target gNB-CU-CP (i.e., the second node).

[0405] The target gNB-CU-UP sends a bearer context establishment response message to the target gNB-CU-CP. The message contains the UE's E1 interface identifier, the successfully established PDU session list, the PDU session list contains the PDU session identifier, the encryption result, and the downlink transport layer address, which is allocated by the gNB-CU-UP and is used to receive downlink data sent by the core network. The message also contains the successfully established DRB list, which contains the DRB identifier, DRB data forwarding information, and the uplink user plane information of the DRB. The uplink user plane information contains the user plane transport layer address, cell group identifier and other information. The uplink user plane address is allocated by the gNB-CU-CP and is used to receive uplink data sent by the DU. The message may also contain the QoS parameters of the received packet data unit set.

[0406] Step 1005: The second node sends a switching response message to the AMF.

[0407] The message contains the destination to source transparent container, the list of accepted sessions, and the list of unaccepted sessions.

[0408] Step 1006: The AMF sends a switching command message to the first node.

[0409] The handover command message contains a transparent container from the destination to the source. The destination base station establishes resources corresponding to the session based on the relevant information of the session contained in the handover request message. The session-related information includes the session identifier, the session contains QoS flow information, and data forwarding suggestions. Based on the forwarding suggestions, the destination base station decides whether data forwarding is required for the session and / or for the DRB. If data forwarding is required, the destination base station allocates a data forwarding address for the session or DRB. The information is contained in the transparent container from the destination to the source.

[0410] The switching command message also carries an RRC reconfiguration request message to be sent to the UE, which carries the configuration information after the switching. The RRC reconfiguration request message sent to the UE is contained in a transparent container from the destination to the source. The data forwarding information includes the identifier of the QoS flow for data forwarding, the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the PDU session, and may also include the identifier of the DRB for data forwarding, and the uplink and / or downlink transport layer IP address and GTP tunnel identifier corresponding to the DRB. If it is direct data forwarding, the uplink and / or downlink transport layer IP address and GTP tunnel identifier are allocated by the destination base station. If it is indirect data forwarding, the uplink and / or downlink transport layer IP address and GTP tunnel identifier are allocated by the core network.

[0411] Step 1007: The first node sends a handover command to the UE.

[0412] The source gNB-CU-CP sends the RRC reconfiguration request message sent by the target base station to the UE.

[0413] Step 1008: The first node sends a bearer context modification request message to the source user plane entity (i.e., the source gNB-CU-UP).

[0414] The source gNB-CU-CP sends a bearer context modification request message to the source gNB-CU-UP, which includes the UE identifier on the E1 interface, the session identifier for data forwarding, and data forwarding information, which includes the transport layer address and tunnel identifier for uplink and / or downlink data forwarding, and the identifier of the QoS flow for data forwarding. The message also includes PDCP SN status request information, which indicates that the source user plane needs to report the PDCP SN status in the response message.

[0415] The message in step 1008 may also include indication information indicating that the first node needs the source user plane to report the status of the PDU set. After receiving the indication information, the source user plane needs to send the status of the PDU set to the first node.

[0416] Step 1009: The source user plane entity sends a bearer context modification response message to the first node.

[0417] The message contains the UE's E1 interface identifier, a list of successfully modified PDU sessions, including session identifiers, data radio bearer identifiers, and PDCP sequence number status information. The PDCP sequence number status information contains the status of the received PDCP SDU, uplink COUNT value, and downlink COUNT value. The COUNT value contains the PDCP SN and hyperframe number (HFN number).

[0418] If the message 1008 includes PDCP SN status request information, or includes indication information that the user plane reports the status of the PDU set, or the user plane establishes a session or QoS flow for the XR service, on the user plane, a certain PDU set has not been fully transmitted, and only part of the received PDUs have been transmitted, for example, the first N PDUs in the PDU set M have been transmitted, and the user plane entity finds that one or more PDUs are lost in the first N PDUs, and the reason for the loss may be that the data is lost in the process of the core network sending data to the first node, or lost in the air interface, if the QoS parameter configuration of the packet data unit set includes PSIHI, and PSIHI is set to "yes", that is, PSIHI indicates that the application layer needs all PDUs of the PDU set to use the PDU set, then the user plane entity includes the sequence number M of the PDU set to be discarded, or indication information and PSSN in the bearer context modification response message, and the indication information indicates that the data packets in the PDU set M are lost, or indicates that the PDUs of the PDU set M are discarded. M is a natural number greater than 0.

[0419] Step 1010: The first node sends an uplink RAN ​​status transfer message to the AMF.

[0420] The uplink RAN ​​status transmission message is when data needs to be forwarded from the source to the destination, and the source base station needs to send the data transmission status on the source base station to the destination base station through the RAN status transmission message. If there is no data forwarding, the uplink or downlink RAN ​​status transmission message in steps 1010 and 1011 can be a new message.

[0421] During a normal handover, the source gNB-CU-CP can suspend data transmission and reception, stop allocating PDCP (Packet Data Convergence Protocol) sequence numbers to downlink service data units (SDUs), and stop sending uplink SDUs to the core network.

[0422] The message of step 1010 includes a RAN state transmission transparent container, which carries the identifier of the DRB, the uplink count value (COUNT value) and the downlink COUNT value of the DRB. After receiving the value, the destination base station assigns the PDCP sequence number included in the DL COUNT value to the first downlink data packet that has not been assigned a PDCP sequence number. If the source base station accepts the uplink data forwarding requested by the destination base station, the message may also include the reception status of the lost or received uplink SDU.

[0423] When the first node initiates an uplink RAN ​​status transmission or a new message, a certain PDU set may not be fully transmitted, and only part of the received PDUs are transmitted, for example, the first N PDUs in the PDU set M are transmitted, and the first node finds that one or more PDUs are lost in the first N PDUs, and the reason for the loss may be that the data is lost in the process of the core network sending data to the first node, or lost in the air interface. If the QoS parameter configuration of the packet data unit set includes PSIHI, and PSIHI is set to "yes", that is, PSIHI indicates that the application layer needs all PDUs of the PDU set to use the PDU set, then the first node includes the sequence number M of the PDU set to be discarded, or indication information and PSSN in the uplink RAN ​​status transmission message or the new message, and the indication information indicates that the data packets in the PDU set M are lost, or indicates that the PDUs of the PDU set M are discarded. M is a natural number greater than 0.

[0424] There are two implementation methods here. Method 1 is that the second node discards the PDU belonging to PDU set M. When the second node receives a GTP-U data packet from the core network, it can know the PDU set to which the received PDU belongs from the PSSN contained in the data packet header. If the second node receives the PDU of the PDU set M, it discards all received PDUs belonging to PDU set M. Method 2 is that the second node notifies the core network UPF that there is a PDU loss in PDU set M, and notifies UPF that it does not need to send all PDUs belonging to PDU M. These methods are all performed under the premise that PSIHI indicates that the application layer needs all PDUs of the PDU set to use the PDU set. Method 1 and Method 2 can be used in combination.

[0425] When the first node forwards data, if it learns that a PDU in the PDU set M is lost, the first node does not forward the PDUs in the set M that have not been transmitted to the UE. It only forwards the PDUs that have not been lost and have not been transmitted to the UE to the second node.

[0426] According to the above-mentioned method 1, the second node receives the sequence number M and / or indication information of the PDU set to be discarded. If the second node receives a GTP-U data packet from the core network, the PDU set to which the received PDU belongs can be known through the PSSN included in the data packet header. If the second node receives a PDU of the PDU set M, all received PDUs belonging to the PDU set M are discarded.

[0427] Step 1011: AMF sends a downlink RAN ​​status transfer message to the second node.

[0428] The message carries the message RAN state transmission transparent container of step 1010. If there is no data forwarding, the message of step 1011 may be a new message.

[0429] Step 1012: The second node sends a bearer context modification request message to a destination user plane entity.

[0430] The target gNB-CU-CP sends a bearer context modification request message to the target gNB-CU-UP. The message includes the UE identifier on the E1 interface, the session identifier and / or DRB identifier for data forwarding, and the PDCP sequence number status information corresponding to the DRB.

[0431] The bearer context modification request message includes the sequence number of the PDU set to be discarded, such as PSSN M, or indication information and PSSN, where the indication information indicates that data packets in PDU set M are lost, or indicates discarding PDUs in PDU set M. M is a natural number greater than 0.

[0432] When the destination gNB-CU-UP receives a GTP-U data packet from the core network, the PDU set to which the received PDU belongs can be known from the PSSN contained in the data packet header. If the destination gNB-CU-UP receives a PDU of the PDU set M, all received PDUs belonging to the PDU set M are discarded.

[0433] Step 1013: The destination user plane entity sends a bearer context modification response message to the second node.

[0434] The target gNB-CU-UP sends a Bearer Context Modification Response message to the target gNB-CU-CP, which includes the UE identifier on the E1 interface.

[0435] Step 1014: The UE synchronizes with the target cell and sends a handover completion message to the target base station.

[0436] Step 1015: The second node sends a path switching notification message to the core network AMF.

[0437] The path switch notification message contains the UE's location information and the PDU session list switched to the target base station. The UE's location information contains the unique identifier of the cell where the UE is located and the tracking area identifier where the UE is located. The specific information of the PDU session switched to the target base station is contained in the SM container, which contains the address of the user plane and the information of the QoS flow.

[0438] According to the above method 2, the path switching notification message includes a PDU set sequence number, which is the sequence number of the PDU set that has not been completely received, or the sequence number of the PDU set that needs to be discarded, such as PSSN M, or indication information and PSSN, and PSSN M and / or indication are obtained from the first node in step 1011. PSSN M and / or indication information can be included in the SM container, or included outside the container. The indication information indicates that the data packets in PDU set M are lost, or indicates that the PDUs of PDU set M are discarded.

[0439] As shown in steps 910 to 913, the AMF may send the PSSN M that needs to be discarded, or the indication information and the PSSN to the UPF. When the UPF receives the PSSN M that needs to be discarded, or the indication information and the PSSN, the UPF may not send all the PDUs belonging to the PSSN M to the new base station (or the new gNB-CU-UP, or the target base station, or the target gNB-CU-UP, the same below), or when the UPF sends data to the new base station, it starts from a complete PDU set. For example, the data of the PSSN M is all sent through the source base station. Starting from a new complete PDU set, the UPF sends data to the target base station. In this way, all the PDUs contained in the PSSN M are sent to the source base station. The source base station may decide to discard the remaining data of the PSSN M according to the situation, or forward the data of the PSSN M to the target base station, and the target base station continues to send it to the UE. After the UPF sends all the PDUs of the PSSN M to the source base station and adds the end mark, the UPF starts to send data to the target base station from a complete PDU set. The process between AMF and UPF is the same as from 910 to 913, and the core network steps are omitted here.

[0440] Step 1016: The second node sends a UE context release request message to the source base station.

[0441] After the UE switches to the target base station, the target gNB-CU-CP can send a UE context release request message to request the source base station to release the stored UE related information and resources.

[0442] So far, the process of the above embodiment is completed.

[0443] Through the above embodiments, when the UE moves, the sending of XR data can be reduced, the resources of the air interface can be saved, and the transmission efficiency of the XR data can be improved.

[0444] Please refer to Fig.12 , Fig.12 FIG. 1 is a schematic diagram for describing a first node sending a message to a second node for controlling data transmission according to various embodiments of the present disclosure. Fig.12 shown.

[0445] Step 1101: The first node sends the nth message to the second node.

[0446] The first node may be a base station, a source base station, a source gNB-CU-UP, a source gNB-CU-CP, an AMF, an SMF, or an UPF, etc. The second node may be a base station, a target base station, a gNB-CU-UP, a source gNB-CU-CP, a target gNB-CU-CP, an AMF, an SMF, or an UPF, etc.

[0447] The nth message may be a control plane message or a user plane message. The user plane message may be information included in a GTP-U header.

[0448] If the nth message is a control plane message, the message may carry a PDU set sequence number. The PDU set sequence number is the sequence number of a PDU set that has not been completely received, and may also be the sequence number of a PDU set that needs to be discarded. When the UE is located at the first node, it is configured with an XR service. The first node is sending a certain PDU set to the UE, and has not yet sent all the PDUs contained in the entire PDU set to the UE. The first node has only transmitted part of the PDUs that have been received, for example, the first N PDUs in the PDU set M, and the first node finds that one or more PDUs are lost in the first N PDUs. The reason for the loss may be that the core network is losing data in the process of sending data to the first node, or the first node is losing data in the process of sending data to the UE over the air interface. If the QoS parameter configuration of the packet data unit set includes PSIHI, and PSIHI is set to "yes", that is, PSIHI indicates that the application layer needs all the PDUs of the PDU set to use the PDU set, then the first node sends a control plane message to the second node. The message includes the sequence number of the PDU set to be discarded, such as PSSN M, or indication information and PSSN, the indication information indicates that data packets in PDU set M are lost, or indicates to discard PDUs in PDU set M, where M is a natural number greater than 0.

[0449] Or the first node receives a message from another node, the message including the sequence number of the PDU set to be discarded, such as PSSN M, or indication information and PSSN, the indication information indicating that data packets in PDU set M are lost, or indicating to discard PDUs in PDU set M, where M is a natural number greater than 0. The first node sends the received PSSN, or the indication information and PSSN, to the second node.

[0450] The first node and the second node may be one of the following combinations, and other combinations are not excluded:

[0451] The first node may be a base station, and the second node may be an AMF or an SMF.

[0452] The first node may be a source base station, and the second node may be an AMF or an SMF.

[0453] The first node may be a destination base station, and the second node may be an AMF or an SMF.

[0454] The first node may be a source base station, and the second node may be a destination base station.

[0455] The first node may be the target gNB-CU-CP, and the second node may be the target gNB-CU-UP.

[0456] The first node is the source gNB-CU-UP and the second node is the source gNB-CU-CP.

[0457] The first node is the AMF and the second node is the source SMF.

[0458] The first node is the SMF and the second node is the UPF.

[0459] The first node is a base station, and the second node is a UPF.

[0460] The first node is gNB-CU-UP and the second node is UPF.

[0461] If the nth message is a user plane message, the first node is a gNB-CU-UP or a base station, and the second node is a UPF, the first node sends user plane information to the second node, and the user plane information may be included in a GTP-U header, and the user plane information includes a sequence number PSSN of a PDU set, a sequence number of a PDU set to be discarded by the PSSN, and indication information indicating whether the user plane information has a PSSN. Specifically, the user plane information may be included in the uplink PDU session information, and the uplink PDU session information includes a PSSN indication (PSSN Ind) and a PSSN.

[0462] If the nth message is a control plane message, the message indicates the path switching, the switching process performed by the UE, and after the switching process is completed, that is, the UE accesses the destination cell, the nth message notifies the completion of the switching and notifies that the data transmission path is switched from the source to the destination. For example, the message can be a switching notification in the Ng switching process, or a path switching request message in the Xn switching process, or other messages. The message is sent by the destination base station to the AMF, and the AMF forwards the information in the message to the UPF through the SMF. The message may include the downlink data receiving address information assigned by the destination base station. Step 1102: The second node takes further action.

[0463] The second node can be a base station, a target base station, a target gNB-CU-UP, a gNB-CU-CP, a target gNB-CU-CP, an AMF, an SMF, or a UPF.

[0464] The further action can be one of the following:

[0465] The second node receives the sequence number M and / or indication information of the PDU set to be discarded. If the second node receives a GTP-U data packet from the third node, the PDU set to which the received PDU belongs can be known through the PSSN included in the data packet header. If the second node receives the PDU of the PDU set M, all received PDUs belonging to the PDU set M are discarded. The third node may be a UPF, and the second node may be a gNB-CU-UP.

[0466] The second node forwards the received nth message or forwards the information received from the nth message to the fourth node. The second node sends a message to the fourth node, and the fourth node can be a base station, a target base station, a target gNB-CU-UP, a gNB-CU-CP, a target gNB-CU-CP, an AMF, an SMF, or a UPF. The message includes a PDU set sequence number, which is the sequence number of the PDU set that has not been completely received, or the sequence number of the PDU set that needs to be discarded. Or indication information and PSSN, the indication information indicates that a data packet in PDU set M is lost, or indicates to discard the PDU of PDU set M, where M is a natural number greater than 0.

[0467] The second node may not send all PDUs belonging to PSSN M to the source gNB-CU-UP according to the PDU set sequence number M, or the indication information and the PSSN. The gNB-CU-UP may be the target gNB-CU-UP in the handover process, or the source gNB-CU-UP, or a gNB-CU-UP that does not initiate the handover process of the UE and currently sends data to the UE and serves the UE. The second node may be the UPF. If the nth message is a message of the user plane, the first node may be the gNB-CU-UP.

[0468] When the second node (in this case, the second node is the UPF) sends data to the fifth node (the fifth node can be the destination base station or the destination gNB-CU-UP), it starts from a complete PDU set. For example, the second node receives the nth message carrying the PDU set sequence number M. The second node can know that the data of PSSN M is lost, and starting from the data of the next new complete PDU set (M+1), the UPF starts to send the data belonging to the new PDU set to the destination base station or the destination gNB-CU-UP.

[0469] The second node receives the nth message and learns that the data transmission path is switched from the source to the destination node (fifth node), and can learn the data receiving address at the destination node. The destination node is the destination base station or the destination gNB-CU-UP. When the second node sends data to the fifth node, it starts from a complete PDU set. For example, the data of PSSN A has been partially sent to the source base station before receiving the nth message. After receiving the nth message, the second node continues to send the PSSN A data to the source base station or the source gNB-CU-UP until all the PDUs belonging to PSSN A are sent. Starting from the data of the next new complete PDU set (A+1), the UPF starts to send the data belonging to the new PDU set to the destination base station or the destination gNB-CU-UP. In this way, all PDUs contained in the PSSN A are sent to the source gNB-CU-UP. The source gNB-CU-UP can decide to discard the remaining data of PSSN A or forward the data of PSSN A to the destination node according to the situation, such as whether there is data loss, or forward the data of PSSN A to the destination node, which continues to send it to the UE.

[0470] Through the above embodiments, when the UE moves, the sending of XR data can be reduced, the resources of the air interface can be saved, and the transmission efficiency of the XR data can be improved.

[0471] It should be noted that the above Fig.12 Can and Figure 8 , Fig. 9 , Fig.10 , Fig.11 When used in combination, the node name needs to be modified adaptively.

[0472] Please refer to Fig.13 , Fig.13 is a block diagram of a network node according to various embodiments of the present disclosure.

[0473] The network node according to the present invention includes a transceiver 1310, a controller 1320 and a memory 1330. The transceiver 1310, the controller 1320 and the memory 1330 are configured to perform the operation of the method and / or embodiment of the present invention. Although the transceiver 1310, the controller 1320 and the memory 1330 are shown as separate entities, they can be implemented as a single entity, such as a single chip. The transceiver 1310, the controller 1320 and the memory 1330 can be electrically connected or coupled to each other. The transceiver 1310 can send signals to other network nodes and receive signals from other network nodes, such as UE, MN, SN, S-SN, T-SN, other candidate T-SN or core network node. The controller 1320 may include one or more processing units, and may control the UE to perform operations and / or functions according to one of the above embodiments. The memory 1130 may store instructions for implementing the operations and / or functions of one of the above embodiments.

[0474] Those skilled in the art will appreciate that the above illustrative embodiments are described herein and are not intended to be limiting. It should be understood that any two or more of the embodiments disclosed herein may be combined in any combination. In addition, other embodiments may be utilized and other changes may be made without departing from the spirit and scope of the subject matter presented herein. It will be readily understood that the various aspects of the invention of the present disclosure as generally described herein and shown in the accompanying drawings may be arranged, replaced, combined, separated and designed in a variety of different configurations, all of which are contemplated herein.

[0475] Those skilled in the art will appreciate that the various illustrative logic boxes, modules, circuits, and steps described in the present application can be implemented as hardware, software, or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, boxes, modules, circuits, and steps are described generally in the form of their function sets above. Whether such function sets are implemented as hardware or software depends on specific applications and the design constraints imposed on the overall system. Technicians can implement the described function sets in different ways for each specific application, but such design decisions should not be interpreted as causing a departure from the scope of the present application.

[0476] The various illustrative logic blocks, modules, and circuits described in this application may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in an alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors cooperating with a DSP core, or any other such configuration.

[0477] The method or algorithm described in the present application can be directly embodied in hardware, in a software module executed by a processor, or in a combination of the two. The software module can reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative, a storage medium can be integrated into a processor. The processor and the storage medium can reside in an ASIC. The ASIC can reside in a user terminal. In an alternative, the processor and the storage medium can reside in a user terminal as discrete components.

[0478] In one or more exemplary designs, the functions may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted as one or more instructions or codes on a computer-readable medium. Computer-readable media include both computer storage media and communication media, the latter including any media that facilitates the transfer of a computer program from one place to another. Storage media may be any available media that can be accessed by a general or special purpose computer.

[0479] The above description is merely an exemplary embodiment of the present application and is not intended to limit the protection scope of the present application. The protection scope of the present application is determined by the appended claims.

Claims

1. A method performed by a second node in a communication system, the method comprising: Sending a first message to the third node, where the first message includes first indication information, where the first indication information is used to indicate whether the second node supports packet data unit (PDU) set processing of an extended reality (XR) service; as well as receiving a second message from a third node, If the first indication information indicates that the second node supports PDU set processing of the XR service, the second message includes XR service configuration information.

2. The method according to claim 1, further comprising: receiving a third message from the first node, where the third message includes or does not include XR service configuration information corresponding to the first node; A fourth message is sent to the first node, where the fourth message includes second indication information, where the second indication information is used to indicate whether the second node supports PDU set processing of the extended reality XR service.

3. The method according to claim 1 or 2, wherein: The second node is a destination base station, the third node is a session management function SMF, or an access and mobility management function AMF, and the first node is a source base station.

4. The method according to claim 1, further comprising: Sending a fifth message to the user plane of the second node, where the fifth message includes or does not include XR service configuration information corresponding to the second node; A sixth message is received from the user plane of the second node, where the sixth message includes third indication information, where the third indication information is used to indicate whether the user plane of the second node supports PDU aggregate processing of the XR service.

5. The method according to any one of claims 1 to 2 or 4, wherein: The XR service configuration information includes at least one of the following: The period of XR data transmitted on the Quality of Service QoS flow, Data burst arrival time, Data survival time, Jitter configuration information QoS flow identification, The type of PDU set, The identifier of the PDU set, The PDU aggregate delay budget PSDB is used to indicate the upper limit of the delay that the PDU aggregate may experience at the user plane function UPF for transmission between the user equipment UE and the N6 termination point. The PDU aggregate error rate PDER is used to indicate the upper limit of the non-congestion related PDU aggregate loss rate. The PDU set integration processing indication PSIHI is used to indicate whether the application layer needs all PDUs in the PDU set when using the PDU set.

6. A method performed by a third node in a communication system, the method comprising: Receive a first message from the second node, where the first message includes first indication information, where the first indication information is used to indicate whether the second node supports packet data unit (PDU) aggregate processing of an extended reality (XR) service; as well as sending a second message to the second node, If the first indication information indicates that the second node supports PDU set processing of the XR service, the second message includes XR service configuration information.

7. A method performed by a first node in a communication system, the method comprising: Sending a third message to the second node, where the third message includes or does not include extended reality XR service configuration information corresponding to the first node; A fourth message is received from the second node, where the fourth message includes second indication information, where the second indication information is used to indicate whether the second node supports packet data unit (PDU) set processing of an extended reality (XR) service.

8. The method according to claim 7, further comprising: A seventh message is sent to the user plane of the first node, where the seventh message includes fourth indication information, and the fourth indication information is used to indicate whether the second node supports PDU set processing of the XR service.

9. The method according to claim 7, further comprising: Sending a radio resource control protocol RRC reconfiguration request message to the user equipment, where the RRC reconfiguration request message includes fifth indication information, where the fifth indication information is used to indicate whether the second node supports PDU set processing of the XR service; The destination cell of the user equipment is selected based on the fifth indication information.

10. A method performed by a second node in a communication system, the method comprising: receiving an eighth message from the first node, wherein the eighth message includes a sequence number PSSN of a packet data unit PDU set; Based on the eighth message, a corresponding operation is performed.

11. The method according to claim 10, wherein: The first node is one of the following: a base station, a source base station, a user plane gNB-CU-UP of a centralized unit of a source base station, a control plane gNB-CU-CP of a centralized unit of a source base station, an access and mobility management function AMF, a session management function SMF, or a user plane function UPF; and / or The second node is one of the following: a base station, a target base station, a target gNB-CU-UP, a source gNB-CU-CP, a target gNB-CU-CP, an AMF, an SMF, or an UPF.

12. The method according to claim 10, wherein: The eighth message further includes sixth indication information, where the sixth indication information is used to indicate that a PDU in the PDU set corresponding to the PSSN is lost or to indicate that the PDU in the PDU set is discarded.

13. The method according to claim 10, wherein: The eighth message is a control plane message or a user plane message.

14. The method according to claim 10, wherein: The method further comprises: receiving a data packet from a third node, The performing of corresponding operations includes: Discarding the PDU in the PDU set corresponding to the PSSN; Wherein, the third node is UPF.

15. The method according to claim 10, wherein: The performing of corresponding operations includes: Sending a ninth message to the fourth node, where the ninth message includes the PSSN and / or seventh indication information, where the seventh indication information is used to indicate that a PDU in the PDU set corresponding to the PSSN is lost or to indicate that the PDU in the PDU set is discarded; Among them, the fourth node is one of the following: a base station, a target base station, a target gNB-CU-UP, a gNB-CU-CP, a target gNB-CU-CP, an AMF, an SMF, or an UPF.

16. The method according to claim 10, wherein: The performing of corresponding operations includes: not sending to the gNB-CU-UP all PDUs belonging to the PDU set corresponding to the PSSN, The gNB-CU-UP is one of the following: a target gNB-CU-UP, a source gNB-CU-UP, or a gNB-CU-UP currently serving a user equipment UE.

17. The method according to claim 10, wherein: The performing of corresponding operations includes: Sending a PDU belonging to a new PDU set to a fifth node, wherein the new PDU set is a next PDU set of the PDU set corresponding to the PSSN; The fifth node is one of the following: a target base station, a target gNB-CU-UP, or a gNB-CU-UP currently serving the UE.

18. A node, comprising: A transceiver configured to transmit and receive signals with the outside; as well as A controller configured to control the transceiver to perform the method according to any one of claims 1-5 or 6 or 7-9 or 10-17.

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