Base station, mobile terminal and node in wireless communication system and method performed by the same

Abstract

The present disclosure provides a base station, a mobile terminal and a node in a wireless communication system and methods performed by the same. A method performed by a Wireless Access Backhaul (WAB)-gNB in a wireless communication system includes: transmitting a first message to a second node, wherein the first message is associated with a request to suspend an NG interface between the WAB-gNB and the second node; and receiving a message in response to the request from the second node, wherein the first message includes at least one of: first time information related to a time for suspending the NG interface, first history location information of the WAB-gNB, second history location information of a co-located wireless access backhaul-mobile terminal (WAB-MT) of the WAB-gNB, information related to a context of the NG interface that the WAB-gNB suggests to release, information related to a context of the NG interface that the WAB-gNB does not suggest to release.

Description

BASE STATION, MOBILE TERMINAL AND NODE IN WIRELESS COMMUNICATION SYSTEM AND METHOD PERFORMED BY THE SAME

[0001] The present disclosure relates to a field of wireless communication technologies, and in particular, to a base station, a mobile terminal and a node in a wireless communication system and methods performed by the same.

[0002] In order to meet an increasing demand for wireless data communication services since a deployment of 4G communication system, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called "beyond 4G network" or "post LTE system".

[0003] Wireless communication is one of the most successful innovations in modern history. Recently, the number of subscribers of wireless communication services has exceeded 5 billion, and it continues growing rapidly. With the increasing popularity of smart phones and other mobile data devices (such as tablet computers, notebook computers, netbooks, e-book readers and machine-type devices) in consumers and enterprises, a demand for wireless data services is growing rapidly. In order to meet rapid growth of mobile data services and support new applications and deployments, it is very important to improve efficiency and coverage of wireless interfaces.

[0004] 5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in "Sub 6GHz" bands such as 3.5GHz, but also in "Above 6GHz" bands referred to as mmWave including 28GHz and 39GHz. In addition, it has been considered to implement 6G mobile communication technologies (referred to as Beyond 5G systems) in terahertz bands (for example, 95GHz to 3THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

[0005] At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive MIMO for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of BWP (BandWidth Part), new channel coding methods such as a LDPC (Low Density Parity Check) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

[0006] Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as V2X (Vehicle-to-everything) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR UE Power Saving, Non-Terrestrial Network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

[0007] Moreover, there has been ongoing standardization in air interface architecture / protocol regarding technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture / service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE positions.

[0008] As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

[0009] Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using OAM (Orbital Angular Momentum), and RIS (Reconfigurable Intelligent Surface), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI (Artificial Intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

[0010] Because the WAB has mobility, it may move from the service scope of an old AMF (e.g., a first AMF) into the service scope of a new AMF (e.g., a second AMF). In this case, the NG interface set up by the WAB-gNB with the old AMF does not need to be reserved, that is, the NG connection between the WAB-gNB and the old AMF can be removed. However, there is also a situation where the WAB may move from the service scope of the old AMF to the service scope of the new AMF, and then return from the service scope of the new AMF to the service scope of the old AMF. In this case, if the NG interface between the WAB-gNB and the old AMF is removed, an NG interface between the WAB-gNB and the old AMF needs to be re-established when the WAB-gNB returns to the old AMF, resulting in more time waste and larger signaling overhead, and the resulting larger delay will further affect the UEs served by the WAB-gNB.

[0011] Embodiments of the present disclosure provide a method performed by a Wireless Access Backhaul (WAB)-gNB in a wireless communication system, including: transmitting a first message to a second node, wherein the first message is associated with a request to suspend an NG interface between the WAB-gNB and the second node; and receiving a message in response to the request from the second node, wherein the first message includes at least one of: first time information related to a time for suspending the NG interface, first history location information of the WAB-gNB, second history location information of a co-located wireless access backhaul-mobile terminal (WAB-MT) of the WAB-gNB, information related to a context of the NG interface that the WAB-gNB suggests to release, information related to a context of the NG interface that the WAB-gNB does not suggest to release; wherein the message includes at least one of: second time information related to a time for suspending the NG interface, and third time information related to a time for disabling a suspend request for the NG interface.

[0012] According to embodiments of the present disclosure, the message is a second message related to the request being accepted, wherein the second message includes second time information related to a time for suspending the NG interface.

[0013] According to embodiments of the present disclosure, the message is a third message, wherein the third message includes at least one of: a first cause value related to the request being rejected, third time information related to a time for disabling a suspend request for the NG interface, wherein in a case that the third message includes the first cause value, the method further includes: transmitting an NG removal request related to the NG interface to the second node and / or performing a removal operation related to the NG interface.

[0014] According to embodiments of the present disclosure, the method further includes: transmitting an NG removal request message related to the NG interface to a third node, wherein the NG removal request message includes name information of the second node and an identifier of the WAB-gNB, wherein the identifier of the WAB-gNB is transmitted by the third node to the second node.

[0015] According to embodiments of the present disclosure, the method further includes: receiving an NG removal response message from the third node, wherein the NG removal response message includes the name information of the second node, wherein the name information of the second node is transmitted by the second node to the third node.

[0016] According to embodiments of the present disclosure, the context of the NG interface that the WAB-gNB suggests to release includes at least one of: information element (IE) whose presence attribute is optional, information element (IE) that changes frequently, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX); and wherein the context of the NG interface that the WAB-gNB does not suggest to release includes at least one of: all information elements (IEs) in the context of the NG interface, information element (IE) whose presence attribute is mandatory, information element (IE) that changes infrequently, global RAN node identifier, RAN node name, extended RAN node name.

[0017] According to embodiments of the present disclosure, the second message further includes at least one of: information related to a context of the NG interface that the second node agrees to release, and information related to a context of the NG interface that the second node does not agree to release.

[0018] According to embodiments of the present disclosure, the method further includes: transmitting a fourth message to the second node, wherein the fourth message is associated with a request to resume the NG interface, wherein the fourth message includes information related to resuming a context of the NG interface.

[0019] According to embodiments of the present disclosure, the context of the NG interface resumed includes at least one of: all information elements (IEs) in the context of the NG interface, IE that is released in the context of the NG interface, IE that is changed and with a presence attribute of mandatory in the context of the NG interface, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX), delta information of changed information elements (IEs).

[0020] Embodiments of the present disclosure provide a method performed by a second node in a wireless communication system, including: receiving a first message from a Wireless Access Backhaul (WAB)-gNB, wherein the first message is associated with a request to suspend an NG interface between the WAB-gNB and the second node; and transmitting a message in response to the request to the WAB-gNB, wherein the first message includes at least one of: first time information related to a time for suspending the NG interface, first history location information of the WAB-gNB, second history location information of a co-located wireless access backhaul-mobile terminal (WAB-MT) of the WAB-gNB, information related to a context of the NG interface that the WAB-gNB suggests to release, information related to a context of the NG interface that the WAB-gNB does not suggest to release; wherein the message includes at least one of: second time information related to a time for suspending the NG interface, and third time information related to a time for disabling a suspend request for the NG interface.

[0021] According to embodiments of the present disclosure, the message is a second message related to the request being accepted, wherein the second message includes second time information related to a time for suspending the NG interface.

[0022] According to embodiments of the present disclosure, the message is a third message, wherein the third message includes at least one of: a first cause value related to the request being rejected, third time information related to a time for disabling a suspend request for the NG interface, wherein in a case that the third message includes the first cause value, the method further includes: receiving an NG removal request related to the NG interface from the WAB-gNB and / or performing a removal operation related to the NG interface.

[0023] According to embodiments of the present disclosure, the method further includes: receiving an identifier of the WAB-gNB from a third node, wherein an NG removal request message related to the NG interface is transmitted from the WAB-gNB to the third node, wherein the NG removal request message includes name information of the second node and an identifier of the WAB-gNB.

[0024] According to embodiments of the present disclosure, the method further includes: transmitting an NG removal response message to the third node, wherein the NG removal response message includes the name information of the second node and an identifier of the WAB-gNB, wherein the name information of the second node is transmitted by the third node to the WAB-gNB.

[0025] According to embodiments of the present disclosure, the context of the NG interface that the WAB-gNB suggests to release includes at least one of: information element (IE) whose presence attribute is optional, information element (IE) that changes frequently, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX); and wherein the context of the NG interface that the WAB-gNB does not suggest to release includes at least one of: all information elements (IEs) in the context of the NG interface, information element (IE) whose presence attribute is mandatory, information element (IE) that changes infrequently, global RAN node identifier, RAN node name, extended RAN node name.

[0026] According to embodiments of the present disclosure, the second message further includes at least one of: information related to a context of the NG interface that the second node agrees to release, and information related to a context of the NG interface that the second node does not agree to release.

[0027] According to embodiments of the present disclosure, the method further includes: receiving a fourth message from the WAB-gNB, wherein the fourth message is associated with a request to resume the NG interface, wherein the fourth message includes information related to resuming a context of the NG interface.

[0028] According to embodiments of the present disclosure, the context of the NG interface resumed includes at least one of: all information elements (IEs) in the context of the NG interface, IE that is released in the context of the NG interface, IE that is changed and with a presence attribute of mandatory in the context of the NG interface, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX), delta information of changed information elements (IEs).

[0029] Embodiments of the present disclosure provide a method performed by a wireless access backhaul-mobile terminal (WAB-MT) in a wireless communication system, including: receiving a first message from a Wireless Access Backhaul (WAB)-gNB, wherein the first message is associated with a request to suspend an NG interface between the WAB-gNB and a second node; transmitting the first message to the second node; and receiving a message in response to the request from the second node, wherein the first message includes at least one of: first time information related to a time for suspending the NG interface, first history location information of the WAB-gNB, second history location information of a co-located wireless access backhaul-mobile terminal (WAB-MT) of the WAB-gNB, information related to a context of the NG interface that the WAB-gNB suggests to release, information related to a context of the NG interface that the WAB-gNB does not suggest to release; wherein the message includes at least one of: second time information related to a time for suspending the NG interface, and third time information related to a time for disabling a suspend request for the NG interface.

[0030] According to embodiments of the present disclosure, the message is a second message related to the request being accepted, wherein the second message includes second time information related to a time for suspending the NG interface.

[0031] According to embodiments of the present disclosure, the message is a third message, wherein the third message includes at least one of: a first cause value related to the request being rejected, third time information related to a time for disabling a suspend request for the NG interface, wherein in a case that the third message includes the first cause value, the method further includes: receiving an NG removal request related to the NG interface from the WAB-gNB; and transmitting an NG removal request related to the NG interface to the second node.

[0032] According to embodiments of the present disclosure, the method further includes: receiving an NG removal request message related to the NG interface from the WAB-gNB; and transmitting the NG removal request message to a third node, wherein the NG removal request message includes name information of the second node and an identifier of the WAB-gNB, wherein the identifier of the WAB-gNB is transmitted by the third node to the second node.

[0033] According to embodiments of the present disclosure, the method further includes: receiving an NG removal response message from the third node; and transmitting the NG removal response message to the WAB-gNB, wherein the NG removal response message includes the name information of the second node, wherein the name information of the second node is transmitted by the second node to the third node.

[0034] According to embodiments of the present disclosure, the context of the NG interface that the WAB-gNB suggests to release includes at least one of: information element (IE) whose presence attribute is optional, information element (IE) that changes frequently, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX); and wherein the context of the NG interface that the WAB-gNB does not suggest to release includes at least one of: all information elements (IEs) in the context of the NG interface, information element (IE) whose presence attribute is mandatory, information element (IE) that changes infrequently, global RAN node identifier, RAN node name, extended RAN node name.

[0035] According to embodiments of the present disclosure, the second message further includes at least one of: information related to a context of the NG interface that the second node agrees to release, and information related to a context of the NG interface that the second node does not agree to release.

[0036] According to embodiments of the present disclosure, the method further includes: receiving a fourth message from the WAB-gNB; and transmitting the fourth message to the second node, wherein the fourth message is associated with a request to resume the NG interface, wherein the fourth message includes information related to resuming a context of the NG interface.

[0037] According to embodiments of the present disclosure, the context of the NG interface resumed includes at least one of: all information elements (IEs) in the context of the NG interface, IE that is released in the context of the NG interface, IE that is changed and with a presence attribute of mandatory in the context of the NG interface, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX), delta information of changed information elements (IEs).

[0038] Embodiments of the present disclosure provide a Wireless Access Backhaul (WAB)-gNB in a wireless communication system, including: a transceiver configured to transmit and receive signals; and a controller coupled to the transceiver and configured to perform any method performed by a WAB-gNB in a wireless communication system according to embodiments of the present disclosure.

[0039] Embodiments of the present disclosure provide a node device in a wireless communication system, including: a transceiver configured to transmit and receive signals; and a controller coupled to the transceiver and configured to perform any method performed by any node device such as a second node in a wireless communication system according to embodiments of the present disclosure.

[0040] Embodiments of the present disclosure provide a wireless access backhaul-mobile terminal (WAB-MT) in a wireless communication system, including: a transceiver configured to transmit and receive signals; and a controller coupled to the transceiver and configured to perform any method performed by a WAB-MT in a wireless communication system according to embodiments of the present disclosure.

[0041] Embodiments of the present disclosure provide a computer-readable medium having computer-readable instructions stored thereon, which when executed by a processor implement any method performed by a node device, a WAB-gNB and / or a WAB-MT in a wireless communication system according to embodiments of the present disclosure.

[0042] The methods performed by the node device, WAB-gNB and / or WAB-MT in the wireless communication system provided by the present disclosure can effectively enhance the NG interface by exchanging information related to NG interface suspend.

[0043] FIG. 1 is an exemplary system architecture of system architecture evolution (SAE);

[0044] FIG. 2 is an exemplary system architecture according to various embodiments of the present disclosure;

[0045] FIG. 3A shows an example structure of a base station according to embodiments of the present disclosure;

[0046] FIG. 3B shows an example structure of a base station according to embodiments of the present disclosure;

[0047] FIG. 3C shows an example structure of a base station according to embodiments of the present disclosure;

[0048] FIG. 4 shows an example architecture diagram of a WAB node in a wireless communication system according to embodiments of the present disclosure;

[0049] FIG. 5A shows an example procedure of NG interface setup according to embodiments of the present disclosure;

[0050] FIG. 5B shows an example procedure of NG interface removal according to embodiments of the present disclosure;

[0051] FIG. 5C shows another example procedure of NG interface removal according to embodiments of the present disclosure;

[0052] FIG. 6A shows an example procedure of NG interface suspend according to embodiments of the present disclosure;

[0053] FIG. 6B shows an example procedure of NG interface suspend according to embodiments of the present disclosure;

[0054] FIG. 7A shows an example procedure of NG interface suspend failure according to embodiments of the present disclosure;

[0055] FIG. 7B shows an example procedure of NG interface suspend failure according to embodiments of the present disclosure;

[0056] FIG. 8A shows an example procedure of NG interface resume according to embodiments of the present disclosure;

[0057] FIG. 8B shows an example procedure of NG interface resume according to embodiments of the present disclosure;

[0058] FIG. 9A shows an example procedure of NG interface resume failure according to embodiments of the present disclosure;

[0059] FIG. 9B shows an example procedure of NG interface resume failure according to embodiments of the present disclosure;

[0060] FIG. 10 shows an example procedure of NG interface suspend according to embodiments of the present disclosure;

[0061] FIG. 11 shows an example procedure of an NG interface from a Suspend state to a Release state according to embodiments of the present disclosure;

[0062] FIG. 12 shows an example procedure for avoiding a BH PDU session for NG interface suspend from being released according to embodiments of the present disclosure;

[0063] FIG. 13A shows an example method for indicating a PDU session type according to embodiments of the present disclosure;

[0064] FIG. 13B shows an example method for indicating a PDU session type according to embodiments of the present disclosure;

[0065] FIG. 14 shows another method for obtaining history location information of a WAB-gNB according to embodiments of the present disclosure;

[0066] FIGs. 15A-15D show an example of a context of an NG interface according to embodiments of the present disclosure;

[0067] FIG. 15E shows an example procedure for context resume for an NG interface according to embodiments of the present disclosure;

[0068] FIG. 16A shows an example procedure for transmitting assistance information to a BH gNB over a Uu interface according to embodiments of the present disclosure;

[0069] FIG. 16B shows another example procedure for transmitting assistance information to a BH gNB over a Uu interface according to embodiments of the present disclosure;

[0070] FIG. 17 shows an example of a correspondence between BH PDU sessions and resources according to embodiments of the present disclosure;

[0071] FIG. 18 shows a flowchart of a method 1800 performed by a wireless access backhaul (WAB)-gNB in a wireless communication system according to embodiments of the present disclosure;

[0072] FIG. 19 shows a flowchart of a method 1900 performed by a second node in a wireless communication system according to embodiments of the present disclosure;

[0073] FIG. 20 shows a flowchart of a method 2000 performed by a wireless access backhaul-mobile terminal (WAB-MT) in a wireless communication system according to embodiments of the present disclosure;

[0074] FIG. 21 shows a schematic diagram of a node 2100 in a wireless communication system according to embodiments of the present disclosure;

[0075] FIG. 22 shows a schematic diagram of a WAB-gNB 2200 in a wireless communication system according to embodiments of the present disclosure; and

[0076] FIG. 23 shows a schematic diagram of a WAB-MT 2300 in a wireless communication system according to embodiments of the present disclosure.

[0077] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

[0078] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Accordingly, 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 purpose only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.

[0079] It is to 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.

[0080] The term "include" or "may include" refers to the existence of a corresponding disclosed function, operation or component which can be used in various embodiments of the present disclosure and does not limit one or more additional functions, operations, or components. Additionally, the terms such as "include" and / or "have" may be construed to denote a certain characteristic, number, step, operation, constituent element, component or a combination thereof, but may not be construed to exclude the existence of or a possibility of addition of one or more other characteristics, numbers, steps, operations, constituent elements, components or combinations thereof.

[0081] The term "or" used in various embodiments of the present disclosure includes any or all of combinations of listed words. For example, the expression "A or B" may include A, may include B, or may include both A and B.

[0082] Unless defined differently, all terms used herein, which include technical terminologies or scientific terminologies, have the same meaning as that understood by a person skilled in the art to which the present disclosure belongs. Such terms as those defined in a generally used dictionary are to be interpreted to have the meanings equal to the contextual meanings in the relevant field of art, and are not to be interpreted to have ideal or excessively formal meanings unless clearly defined in the present disclosure.

[0083] The drawings discussed below and various embodiments for describing the principles of the present disclosure in this patent document are only for illustration and should not be interpreted as limiting the scope of the disclosure in any way. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any suitably arranged system or device.

[0084] FIG. 1 is an exemplary system architecture 100 of system architecture evolution (SAE). User equipment (UE) 101 is a terminal device for receiving data. An evolved universal terrestrial radio access network (E-UTRAN) 102 is a radio access network, which includes a macro base station (eNodeB / NodeB) that provides UE with interfaces to access the radio network. A mobility management entity (MME) 103 is responsible for managing mobility context, session context and security information of the UE. A serving gateway (SGW) 104 mainly provides functions of user plane, and the MME 103 and the SGW 104 may be in the same physical entity. A packet data network gateway (PGW) 105 is responsible for functions of charging, lawful interception, etc., and may be in the same physical entity as the SGW 104. A policy and charging rules function entity (PCRF) 106 provides quality of service (QoS) policies and charging criteria. A general packet radio service support node (SGSN) 108 is a network node device that provides routing for data transmission in a universal mobile telecommunications system (UMTS). A home subscriber server (HSS) 109 is a home subsystem of the UE, and is responsible for protecting user information including a current location of the user equipment, an address of a serving node, user security information, and packet data context of the user equipment, etc.

[0085] FIG. 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.

[0086] User equipment (UE) 201 is a terminal device for receiving data. A next generation radio access network (NG-RAN) 202 is a radio access network, which includes a base station (a gNB or an eNB connected to 5G core network 5GC, and the eNB connected to the 5GC is also called ng-eNB) that provides UE with interfaces to access the radio network. An access and mobility management function (AMF) entity 203 is responsible for managing mobility context and security information of the UE. A user plane function (UPF) entity 204 mainly provides functions of user plane. A session management function SMF entity 205 is responsible for session management. A data network (DN) 206 includes, for example, services of operators, access of Internet and service of third parties.

[0087] In an NR system, in order to support network function virtualization and more efficient resource management and scheduling, a base station (gNB / ng-eNB) that provides wireless network interfaces for terminals (UEs) may be further divided into a centralized unit (for example, gNB-CU / ng-eNB-CU (gNB central unit / ng-eNB central unit)) and a distributed unit (for example, gNB-DU / ng-eNB-DU (gNB distributed unit / ng-eNB distributed unit)) (abbreviated as CU and DU in the present disclosure), as shown in FIG. 3A. gNB-CU has radio resource control (RRC), Service Data Adaptation Protocol (SDAP) and Packet Data Convergence Protocol (PDCP) protocol layers, while ng-eNB-CU has RRC and PDCP layers. gNB-DU / ng-eNB-DU has Radio Link Control (RLC) protocol, Media Access Control (MAC) and physical (PHY) layers. 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 a control plane F1-C and a user plane F1-U. The transport network layer of F1-C is based on IP transport. In order to transmit signaling more reliably, stream control transmission protocol (SCTP) protocol is added onto IP. The protocol of the application layer is F1 Application Protocol (F1AP). SCTP can provide reliable application layer message transmission. The transport layer of F1-U is UDP / IP, and the GPRS tunneling protocol-user plane (GTP-U) is used to carry the user plane protocol data unit (PDU) above UDP / IP. Further, for a gNB-CU, as shown in FIG. 3B, the gNB-CU may include a gNB-CU-CP (control plane part of a centralized unit of a base station) and a gNB-CU-UP (user plane part of a centralized unit of a base station), a gNB-CU-CP contains functions of a control plane of a base station and has RRC and SDAP protocol layers, and a gNB-CU-UP contains functions of a user plane of a base station and has SDAP and PDCP protocol layers. There is a standardized public interface E1 between gNB-CU-CP and gNB-CU-UP, and the protocol is E1 Application Protocol (E1AP). The interface between the control plane part of the centralized unit of the base station and the distributed unit of the base station is an F1-C interface, that is, 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 an F1-U interface, that is, the user plane interface of F1. In addition, in the NR system, a base station providing the E-UTRA user plane and control plane which accessed a 5G core network is called ng-eNB. In order to support virtualization, such a base station (ng-eNB) may also be further divided into a centralized unit ng-eNB-CU (gNB central unit / ng-eNB central unit) and a distributed unit ng-eNB-DU (gNB distributed unit / ng-eNB distributed unit) (abbreviated as CU and DU in the present disclosure), as shown in FIG. 3C. ng-eNB-CU has RRC and PDCP layers. gNB-DU / ng-eNB-DU has radio link control (RLC) protocol, media access control (MAC) and physical layer. There is a standardized public interface W1 between ng-eNB-CU and ng-eNB-DU. The W1 interface is divided into a control plane W1-C and a user plane W1-U. The transport network layer of W1-C is based on IP transport. In order to transmit signaling more reliably, SCTP protocol is added onto IP. The protocol of the application layer is W1 Application Protocol (W1AP). The transport layer of W1-U is UDP / IP, and GTP-U is used to carry user plane protocol data unit (PDU) above UDP / IP.

[0088] In 5G communication technology, faster transmission speeds than 4G are achieved because higher frequencies are used. However, higher frequencies will also lead to shorter transmission distances, so more base stations will be deployed in a 5G network to ensure coverage of the 5G network. However, in fact, normal deployment of 5G base stations in some areas is not possible due to environmental or cost reasons. Therefore, in order to make up for the problem that 5G base stations cannot cover these areas, Wireless Access Backhaul (WAB) technology is proposed to ensure normal communication of users.

[0089] A WAB node (or WAB for short) may include two parts: a WAB base station (e.g., WAB-gNB) and a WAB-MT (mobile terminal). Specifically, FIG. 4 shows an example architecture diagram of a WAB node in a wireless communication system according to embodiments of the present disclosure. As shown in FIG. 4:

[0090] the WAB-gNB provides communication services for UEs through an air interface (e.g., NR Uu);

[0091] the WAB-MT is connected to a backhaul (BH) radio access network node (BH-RAN-Node) (for example, BH gNB) through an air interface, thereby providing backhaul for the WAB-gNB;

[0092] the BH gNB is connected to a BH 5GC, which is a 5GC of the WAB-MT (WAB-MT's 5GC), and the BH gNB and the BH 5GC establish a BH Protocol Data Unit session (BH PDU session) for the WAB-MT;

[0093] the BH 5GC is connected to a 5GC of the UE (UE's 5GC), and the 5GC of the UE provides communication services for the UEs under the WAB-gNB;

[0094] the WAB-gNB transmits data for the UE with the UE's 5GC through the BH PDU session; and

[0095] the WAB-gNB establishes an NG interface (e.g., NG-C / NG-U) with the UE's 5GC through the BH PDU session, and establishes an Xn interface (e.g., Xn-C / Xn-U) with a neighbor base station through the BH PDU session.

[0096] WAB has mobility. The WAB-MT can support at least a part of UE functions, and the WAB-gNB may be a complete base station. The WAB-gNB may perform setup and removal of an NG interface with the 5GC of the UE through a BH PDU session, the processes of which are shown in FIGs. 5A-5C. Hereinafter, description is made taking the NG-RAN node as an example of the WAB-gNB, and the AMF as an example of the 5GC of the UE.

[0097] FIG. 5A shows an example procedure of NG interface setup according to embodiments of the present disclosure. As shown in FIG. 5A, the WAB-gNB (e.g., NG-RAN node) transmits an NG SETUP REQUEST message to the AMF. If the AMF agrees with the NG setup request of the WAB-gNB, an NG SETUP RESPONSE message may be replied to the WAB-gNB.

[0098] FIG. 5B shows an example procedure of NG interface removal according to embodiments of the present disclosure. As shown in FIG. 5B, the WAB-gNB (e.g., NG-RAN node) transmits an NG REMOVAL REQUEST message to the AMF. If the AMF agrees with the NG removal request of the WAB-gNB, an NG REMOVAL RESPONSE message may be replied to the WAB-gNB.

[0099] FIG. 5C shows another example procedure of NG interface removal according to embodiments of the present disclosure. As shown in FIG. 5C, the WAB-gNB (e.g., NG-RAN node) transmits an NG REMOVAL REQUEST message to the AMF. If the AMF does not agree with the NG removal request of the WAB-gNB, an NG REMOVAL FAILURE may be replied to the WAB-gNB.

[0100] Because the WAB has mobility, it may move from the service scope of an old AMF (e.g., a first AMF) into the service scope of a new AMF (e.g., a second AMF). In this case, the NG interface set up by the WAB-gNB with the old AMF does not need to be reserved, that is, the NG connection between the WAB-gNB and the old AMF can be removed. However, there is also a situation where the WAB may move from the service scope of the old AMF to the service scope of the new AMF, and then return from the service scope of the new AMF to the service scope of the old AMF. In this case, if the NG interface between the WAB-gNB and the old AMF is removed, an NG interface between the WAB-gNB and the old AMF needs to be re-established when the WAB-gNB returns to the old AMF, resulting in more time waste and larger signaling overhead, and the resulting larger delay will further affect the UEs served by the WAB-gNB. So for this case, it is necessary to introduce an NG Suspend mechanism, i.e., the NG interface is suspended instead of being completely removed.

[0101] In order to solve the above technical problems, the present disclosure proposes some processing methods of the NG interface, thereby realizing transitions between different states of the NG interface (e.g., an NG Connection state, an NG Suspend state, an NG Removal state, etc.), for example:

[0102] · NG Connection state to an NG Suspend state;

[0103] · NG Suspend state to an NG Connection state;

[0104] · NG Suspend state to an NG Removal state, and so on.

[0105] Exemplary embodiments of the present disclosure are further described below with reference to the accompanying drawings.

[0106] 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, based on the disclosure herein, it will be apparent to those skilled in the art that changes may be made to the illustrated embodiments and examples without departing from the scope of the present disclosure.

[0107] Before introducing the specific content, some assumptions and some definitions of the present disclosure are given below.

[0108] The message names in the present disclosure are just examples, and other message names may be used.

[0109] The "first" and "second" included in the message names in the present disclosure are only examples, and they do not represent an execution order.

[0110] A detailed description of steps irrelevant to the present disclosure is omitted in the present disclosure.

[0111] In the present disclosure, steps in various processes may be combined with each other or performed independently. The execution steps in each process are only examples, and other possible execution orders are not excluded.

[0112] In the present disclosure, a base station may be a 5G base station (e.g., gNB, ng-eNB, etc.), a 4G base station (e.g., eNB, etc.), a 6G base station, a WAB node or WAB-gNB, or other types of access nodes.

[0113] In the present disclosure, transmission of data refers to the reception and / or transmission of data.

[0114] In the present disclosure, "agree" and "accept" can be used interchangeably, and "disagree", "not accept" and "reject" and the like can also be used interchangeably.

[0115] The first aspect: states of NG interface and related procedures

[0116] Because the state of an NG interface (e.g., a Connection state, a Removal state or a Suspend state) is related to the location of the WAB-gNB and its mobility state, the WAB-gNB itself knows its location information, and the AMF can also obtain the location information of the WAB-gNB through an Operation Administration and Maintenance (OAM), etc., so the suspension procedure of the NG interface can be triggered by the WAB-gNB or the AMF.

[0117] FIG. 6A shows an example procedure of NG interface suspend according to embodiments of the present disclosure. When the NG suspend procedure is triggered by WAB-gNB, its flow is shown in FIG. 6A. The WAB-gNB (e.g., NG-RAN node) transmits to the AMF a first message (e.g., NG SUSPEND REQUEST message) associated with a request for suspending the NG interface between the WAB-gNB and the AMF. If the AMF agrees to the request, a second message (e.g., NG SUSPEND RESPONSE message) may be replied to the WAB-gNB. The second message may be a message related to that the request for NG suspending is accepted.

[0118] FIG. 6B shows an example procedure of NG interface suspend according to embodiments of the present disclosure. When the NG suspend procedure is triggered by the AMF, its flow is shown in FIG. 6B. The AMF transmits to the WAB-gNB (e.g., NG-RAN node) a first message (e.g., NG SUSPEND REQUEST message) associated with a request for suspending the NG interface between the WAB-gNB and the AMF. If the WAB-gNB agrees to the request, a second message (e.g., NG SUSPEND RESPONSE message) may be replied to the AMF.

[0119] When the entity receiving the NG suspend request (e.g., WAB-gNB or AMF) cannot correctly parse some information elements (IEs) in the message, or does not want to accept the request for NG interface suspending, the request may be rejected.

[0120] FIG. 7A shows an example procedure of NG interface suspend failure according to embodiments of the present disclosure. When the NG suspend procedure is triggered by the WAB-gNB, if the AMF cannot correctly parse some IEs in the first message (e.g., NG suspend request) transmitted by the WAB-gNB, or does not want to accept the request for NG interface suspending, the AMF may reply to the WAB-gNB with a third message (e.g., NG SUSPEND FAILURE), as shown in FIG. 7A. The third message may be a message related to that the NG suspend request is rejected or failed.

[0121] FIG. 7B shows an example procedure of NG interface suspend failure according to embodiments of the present disclosure. When the NG suspend procedure is triggered by the AMF, if the WAB-gNB cannot correctly parse some IEs in the first message (e.g., NG suspend request) transmitted by the AMF, or does not want to accept the request for NG interface suspending, the WAB-gNB may reply to the AMF with a third message (e.g., NG suspend failure), as shown in FIG. 7B.

[0122] When the NG interface is in a Suspend state, if the WAB-gNB or AMF expects to resume the connection of the NG interface, an NG interface resume procedure may be initiated.

[0123] FIG. 8A shows an example procedure of NG interface resume according to embodiments of the present disclosure. When the NG interface resume procedure is triggered by WAB-gNB, its flow is shown in FIG. 8A. The WAB-gNB (e.g., NG-RAN node) transmits a fourth message (e.g., NG RESUME REQUEST message) to the AMF. If the AMF agrees to the request, a fifth message (e.g., NG RESUME RESONSE message) may be replied to the WAB-gNB. The fourth message may be a message related to a request for resuming the NG interface between the WAB-gNB and the AMF.

[0124] FIG. 8B shows an example procedure of NG interface resume according to embodiments of the present disclosure. When the NG interface resume procedure is triggered by AMF, its flow is shown in FIG. 8B. The AMF transmits a fourth message (e.g., NG RESUME REQUEST message) to the WAB-gNB (e.g., NG-RAN node). If the WAB-gNB agrees to the request, a fifth message (e.g., NG RESUME RESONSE message) may be replied to the AMF.

[0125] When the NG interface is in a Suspend state and an NG interface resume procedure is performed, if the entity (e.g., WAB-gNB or AMF) receiving the NG resume request cannot correctly parse some IEs in the message, or does not want to accept the request for NG interface resuming, the resume request may also be rejected.

[0126] FIG. 9A shows an example procedure of NG interface resume failure according to embodiments of the present disclosure. When the NG interface resume procedure is triggered by the WAB-gNB, if the AMF cannot correctly parse some IEs in the fourth message (e.g., NG RESUME REQUEST message) transmitted by the WAB-gNB, or does not want to accept the request for NG interface resuming, the AMF may reply to the WAB-gNB with a sixth message (e.g., NG RESUME FAILURE), as shown in FIG. 9A.

[0127] FIG. 9B shows an example procedure of NG interface resume failure according to embodiments of the present disclosure. When the NG interface resume procedure is triggered by the AMF, if the WAB-gNB cannot correctly parse some IEs in the fourth message (for example, NG RESUME REQUEST) transmitted by the AMF, or does not want to accept the request for NG interface resuming, the WAB-gNB may reply to the AMF with a sixth message (for example, NG RESUME FAILURE), as shown in FIG. 9B.

[0128] It should be understood that in the procedures of setup, removal, suspe

[0129] nd or resume of the NG interface as described above, all operations of the NG interface and corresponding signaling enhancements need to be completed through the established BH PDU sessions between the WAB-MT and the BH gNB and BH-5GC. For example, the WAB-gNB transmitting a message to the AMF may be that the WAB-gNB first transmits the message to the WAB-MT, and then the WAB-MT transmits the message to the AMF (for example, through the established BH PDU sessions between the WAB-MT and the BH gNB and BH-5GC, and the connection between the BH-5GC and the AMF, etc.). Similarly, the AMF transmitting a message to the WAB-gNB may be that the AMF first transmits the message to the WAB-MT, and then the WAB-MT transmits the message to the WAB-gNB.

[0130] In addition, hereinafter, methods of the present disclosure will be exemplified by taking procedures such as NG removal, NG suspend, NG resume or the like which are triggered by a WAB-gNB as examples. However, corresponding procedures triggered by an AMF are not excluded. According to actual implementation, the methods for WAB-gNB to trigger NG removal, NG suspend, NG resume and other procedures exemplified in the present disclosure may also be appropriately applied to NG removal, NG suspend, NG resume and other procedures triggered by AMF.

[0131] The second aspect: optimization for an NG interface Suspend state

[0132] When the WAB-gNB moves from one AMF (e.g., a first AMF) to another AMF (e.g., a second AMF), in some scenarios, the WAB node knows its future motion trajectory, that is, the WAB node knows whether it will come back into the service scope of the first AMF, and even when it may come back into the service scope of the first AMF. In this case, if the WAB-gNB adds some assistance information and provides it to the AMF during the NG suspend request procedure, it may facilitate the AMF to agree to the WAB-gNB's request for NG interface suspending.

[0133] FIG. 10 shows an example procedure of NG interface suspend according to embodiments of the present disclosure. An example procedure of NG interface suspend as shown in FIG. 10 and corresponding enhancements is described below.

[0134] When the WAB-gNB transmits a first message (e.g., NG suspend request) to the AMF, first information may be added in the first message.

[0135] The first information may include first time information, which may be associated with a time for suspending the NG interface, which, for example, may be a time threshold, a time period, a time range, a duration, a timer, a timer value, etc. Taking Timer 1 as shown in FIG. 10 as an example, it may be used to indicate to the AMF that after Timer 1 expires (more generally, after the time represented by the first time information), the AMF can perform an NG removal procedure, that is, release the suspended NG interface. According to the first information, the AMF can know how long the NG interface needs to be suspended, and can also reduce the signaling overhead of releasing the NG interface by performing an NG removal procedure.

[0136] Optionally, the AMF may obtain history location information of the WAB-gNB from the OAM of the WAB-gNB according to the WAB-gNB identification (WAB-gNB ID) carried in the first message and / or the NG suspend request, so as to help the AMF make decisions (for example, whether to agree or reject the NG suspend request).

[0137] The AMF may reply with a second message (e.g., NG suspend response) to the WAB-gNB.

[0138] In some implementations, if the first message does not include the first information, the AMF may optionally add second information in the second message. The second information may include second time information, which may be associated with a time for suspending the NG interface, which, for example, may be a time threshold, a time period, a time range, a duration, a timer, a timer value, etc. Taking Timer 2 as shown in FIG. 10 as an example, it may be used to indicate to the WAB-gNB that after Timer 2 expires (more generally, after the time represented by the second time information), the AMF will perform an NG removal procedure, that is, release the suspended NG interface.

[0139] In some implementations, if the first message includes the first information and the AMF agrees to the NG suspend request and the first information, the AMF may directly reply to the WAB-gNB with the second message. In the present disclosure, the second message may include information related to that the NG suspend request is accepted (e.g., an "Accepted" identification).

[0140] In some implementations, if the first message includes the first information, and the AMF agrees to the NG suspend request but does not accept the first information (e.g., Timer 1), the above-mentioned second information (e.g., Timer 2) may also be added in the second message to indicate to the WAB-gNB that after Timer 2 expires, the AMF will perform an NG removal procedure, that is, release the suspended NG interface.

[0141] More generally, according to embodiments of the present disclosure, regardless of whether the first information is included in the first message, the AMF may reply with a second message including information related to that the NG suspend request is accepted (e.g., an "Accepted" identification) and / or the second information as shown above.

[0142] FIG. 11 shows an example procedure of an NG interface from a Suspend state to a Release state according to embodiments of the present disclosure.

[0143] When the NG interface between the WAB-gNB and a first AMF (e.g., AMF1 in FIG. 11) is in a Connection state or Suspend state, the WAB-MT of the WAB node may be handed over from a first BH gNB to a second BH gNB (e.g., the new BH gNB in FIG. 11) because of the mobility of the WAB node. Because corresponding BH PDU sessions can be established between the WAB-MT and the BH gNB for different types of interface data (for example, Xn traffic, NG traffic or OAM traffic), so when the WAB-MT is handed over to the second BH gNB, the second BH gNB may release the original BH PDU session used for the NG interface between the WAB-gNB and the first AMF, and establishes a new BH PDU session for the NG connection between the WAB-gNB and a second AMF (e.g., AMF2 in FIG. 11), resulting in a disconnection of the NG interface between the WAB-gNB and the first AMF. In this case, the WAB-gNB knows that the BH PDU session maintaining the NG interface between the WAB-gNB and the first AMF is released, while the first AMF does not know this, so the first AMF may still continue to store the context of the corresponding NG interface. Therefore, the WAB-gNB needs to initiate an NG removal procedure to the first AMF to release the context of the corresponding NG interface. An example procedure is shown in FIG. 11, and the specific steps are as follows.

[0144] The WAB-gNB may transmit an NG removal request message to AMF2 and add third information in the message.

[0145] The third information may include a name of the old AMF (e.g., AMF1 name), and / or a node identifier (e.g., global RAN node ID, etc.) of the WAB-gNB.

[0146] After AMF2 receives the NG removal request message transmitted by WAB-gNB, if AMF2 finds that the AMF name included in the message is not the name of AMF2 (e.g., AMF2 name), the NG interface between AMF2 and WAB-gNB will not be released. If AMF2 finds that the name of AMF1 is included in the third information, AMF2 may transmit an NG removal request to AMF1 and include therein the node identifier (e.g., global RAN node ID, etc.) of the WAB-gNB.

[0147] After AMF1 receives the NG removal request transmitted by AMF2, it can release the NG interface between AMF1 and WAB-gNB according to the third information, that is, completely remove the connection of the NG interface between AMF1 and WAB-gNB.

[0148] AMF1 transmits an NG removal response message to AMF2, and may include fourth information therein.

[0149] The fourth information may include the name of AMF1, and / or a node identifier (e.g., global RAN node ID, etc.) of the WAB-gNB.

[0150] After AMF2 receives the NG removal response transmitted by AMF1, it may then transmit the NG removal response to the WAB-gNB according to the fourth information.

[0151] After receiving the NG removal response transmitted by AMF2, the WAB-gNB may determine based on the fourth information that AMF1 has agreed to release the connection of the NG interface between AMF1 and WAB-gNB.

[0152] The above flows can also be applied to a situation of releasing the NG interfaces between multiple AMFs and WAB-gNB, that is, WAB-gNB may release the NG interfaces with, for example, AMF1, AMF3 and AMF4, etc., through AMF2. In this case, the WAB-gNB needs to add the name of AMF1 (AMF1 name), the name of AMF3 (AMF3 name), the name of AMF4 (AMF4 name) and the node identifier (e.g., global RAN node ID, etc.) of the WAB-gNB in the NG removal request transmitted to AMF2. After receiving the message, AMF2 may then transmit the NG removal request to AMF1, AMF3 and AMF4 according to the name of AMF1, the name of AMF3 and the name of AMF4. The subsequent flow is similar to the above example procedure and will not be described again here.

[0153] In the case where the WAB node's WAB-MT is handed over from a first BH gNB to a second BH gNB, the second BH gNB still reserves the original BH PDU session used for the NG interface between the WAB-gNB and the first AMF (e.g., AMF1 in FIG. 11) and further sets up a new BH PDU session for the NG connection between the WAB-gNB and the second AMF (e.g., AMF2 in FIG. 11), the WAB node may also actively transmit an NG removal request to the first AMF. When the NG interface between the WAB node and the first AMF is removed, the corresponding BH PDU session may not be needed. Therefore, the WAB-MT may transmit indication information to the BH 5GC through a non-access stratum (NAS) message, indicating the BH 5GC to release the corresponding BH PDU session (or BH PDU session ID).

[0154] As described above, the first BH gNB (e.g., the source BH gNB in FIG. 12) may handover the WAB-MT to the second BH gNB (e.g., the target BH gNB in FIG. 12) because of the mobility of the WAB. In order to prevent the second BH gNB from releasing the original BH PDU session used for the NG interface between the WAB-gNB and the first AMF, corresponding enhancements need to be made during the handover procedure of the WAB-MT.

[0155] FIG. 12 shows an example procedure for avoiding a BH PDU session for NG interface suspend from being released according to embodiments of the present disclosure. The specific steps are described below.

[0156] When the source BH gNB decides to handover the WAB-MT to the target BH gNB, it may transmit a handover request message to the target BH gNB and add fifth information into the message.

[0157] Optionally, the fifth information may be provided by the WAB-MT to the source BH gNB through an RRC message (e.g., UE assistance information). It can also be provided by the BH AMF to the source BH gNB through NG interface signaling (e.g., core network assistance information), etc.

[0158] The fifth information may include information related to one or more PDU session IDs, and may be used to indicate at least one of the following information to the target BH gNB:

[0159] the one or more PDU session IDs cannot be released;

[0160] the one or more PDU session IDs need to be reserved;

[0161] the one or more PDU session IDs are BH PDU sessions;

[0162] the one or more PDU session IDs are BH PDU sessions and are used to maintain the NG interface of the WAB-gNB;

[0163] the one or more PDU session IDs are BH PDU sessions and are used to maintain the Xn interface of the WAB-gNB;

[0164] the one or more PDU session IDs are BH PDU sessions and are used to maintain OAM related traffic of the WAB-gNB.

[0165] the fifth information may also include information indicating the target BH gNB to allocate resources and / or to allocate how many resources (i.e., the amount of allocated resources) for the one or more PDU session IDs.

[0166] The fifth information may also include a PDU session type of one or more PDU session IDs.

[0167] FIG. 13A shows an example method for indicating a PDU session type according to embodiments of the present disclosure. As shown in FIG. 13A, a new type may be added in the existing PDU session type, e.g., BH PDU session. The target BH gNB can know PDU sessions corresponding to which PDU session IDs are BH PDU sessions according to the fifth information.

[0168] FIG. 13B shows an example method for indicating a PDU session type according to embodiments of the present disclosure. As shown in FIG. 13B, a new IE, for example, BH PDU Session Type, may be introduced, and specific options for BH PDU session types such as Xn traffic, NG traffic, OAM traffic may be introduced in this IE. The target BH gNB can know PDU sessions corresponding to which PDU session IDs are BH PDU sessions according to the fifth information, and can also know whether these BH PDU sessions are used to transmit Xn traffic or NG traffic or OAM traffic.

[0169] After the target BH gNB receives a handover (HO) request message, if the target BH gNB agrees to the handover request, it may reply a handover request acknowledge (ACK) message to the source BH gNB and add sixth information in the message, where the sixth information may be used to indicate to the source BH gNB at least one of:

[0170] agree or disagree (reject) the one or more PDU session IDs to be released;

[0171] agree or disagree the one or more PDU session IDs to be reserved;

[0172] agree or disagree to allocate corresponding resources for the one or more PDU session IDs;

[0173] when the fifth information includes one or more PDU session IDs, the sixth information may indicate PDU sessions corresponding to which PDU session IDs are agreed to be reserved, and / or PDU sessions corresponding to which PDU session IDs are not agreed to be reserved;

[0174] when the fifth information includes one or more PDU session IDs, the sixth information may indicate for which PDU session IDs are agreed to be allocated corresponding resources, and / or for which PDU session IDs are not agreed to be allocated corresponding resources.

[0175] The sixth information may be transmitted by reusing the existing PDU Session Resources Admitted List IE and / or PDU Session Resources Not Admitted List IE, etc., or it may also be transmitted through any new IE, which is not limited herein.

[0176] As mentioned above, the AMF may obtain the history location information of the WAB-gNB from the OAM of the WAB-gNB. FIG. 14 shows another method for obtaining history location information of a WAB-gNB according to embodiments of the present disclosure. As shown in FIG. 14, in a first case (e.g., WAB-gNB is in a Connection state with AMF and WAB-gNB expects to perform NG suspend):

[0177] When the WAB-gNB transmits an NG suspend request message to the AMF, seventh information may be added to the message to assist the AMF in making decisions, for example, about whether to agree to the WAB-gNB's request for NG suspending.

[0178] The seventh information may include at least one of history location information of the WAB-gNB and / or history location information of the co-located WAB-MT of the WAB-gNB.

[0179] After the AMF receives the NG suspend request including the seventh information, if the AMF does not agree to the NG suspend request of the WAB-gNB and expects to perform an NG removal operation, it may reply an NG suspend failure message to the WAB-gNB, and add eighth information to the message.

[0180] The eighth information may include a first cause value that may be used to indicate to the WAB-gNB the reason for NG suspend failure, e.g., the AMF disagrees with the WAB-gNB's request for NG suspending, but lets the WAB-gNB perform an NG removal operation.

[0181] After the WAB-gNB receives the NG suspend failure including the eighth information, the WAB-gNB may directly perform an NG removal operation (for example, according to the first cause value) without transmitting an NG removal request to the AMF. Meanwhile, the AMF may also perform an NG removal operation directly. In this case, the behavior of the WAB-gNB may be consistent with the behavior after the WAB-gNB receives an NG removal response. In addition, after the WAB-gNB receives the NG suspend failure including the eighth information, the WAB-gNB may also transmit an NG removal request to the AMF (for example, according to the first cause value).

[0182] In a second case (e.g., WAB-gNB is in a Connection state with AMF and WAB-gNB expects to perform NG removal):

[0183] When the WAB-gNB transmits an NG removal request message to the AMF, seventh information may be added to the message to assist the AMF in making decisions, for example, about whether to agree to the WAB-gNB's request for NG removal.

[0184] The seventh information may include at least one of history location information of the WAB-gNB and / or history location information of the co-located WAB-MT of the WAB-gNB.

[0185] After the AMF receives the NG removal request including the seventh information, if the AMF does not agree to the NG removal request of the WAB-gNB and expects to perform an NG suspend operation, it may reply an NG removal failure message to the WAB-gNB, and add ninth information to the message.

[0186] The ninth information may include a second cause value that may be used to indicate to the WAB-gNB the reason for NG removal failure, e.g., the AMF disagrees with the WAB-gNB's request for NG removal, but lets the WAB-gNB perform an NG suspend operation.

[0187] After the WAB-gNB receives the NG removal failure including the ninth information, the WAB-gNB may directly perform an NG suspend operation (for example, according to the second cause value) without transmitting an NG suspend request to the AMF. Meanwhile, the AMF may also perform an NG suspend operation directly. In this case, the behavior of the WAB-gNB may be consistent with the behavior after the WAB-gNB receives an NG suspend response. In addition, after the WAB-gNB receives the NG removal failure including the ninth information, the WAB-gNB may also transmit an NG suspend request to the AMF (for example, according to the second cause value).

[0188] In a third case (e.g., WAB-gNB is in a Connection state with AMF and WAB-gNB expects to perform NG removal or NG suspend):

[0189] When the WAB-gNB transmits an NG removal request message or an NG suspend request message to the AMF, seventh information may be added to the message to assist the AMF in making decisions, for example, about whether to agree to the WAB-gNB's request for NG removal or NG suspending.

[0190] The seventh information may include at least one of history location information of the WAB-gNB and / or history location information of the co-located WAB-MT of the WAB-gNB.

[0191] After the AMF receives the NG removal request or NG suspend request including the seventh information, if the AMF does not agree to the NG removal request or NG suspend request of the WAB-gNB and wants to prevent the WAB-gNB from initiating an NG removal request or NG suspend request again too frequently, it may reply to the WAB-gNB with an NG removal failure message or an NG suspend failure message, and add tenth information in the message.

[0192] The tenth information may include third time information, which may be associated with a time for disabling a suspend request for the NG interface, which, for example, may be a time threshold, a time period, a time range, a duration, a timer, a timer value, etc. Taking Timer 3 as shown in FIG. 14 as an example, it may be used to indicate to the WAB-gNB that the NG removal request or the NG suspend request cannot be triggered again before Timer 3 expires.

[0193] After the WAB-gNB receives the NG removal failure or NG suspend failure message including the tenth information, the WAB-gNB does not perform NG removal or NG suspend related operations, and does not initiate an NG removal request or NG suspend request again before Timer 3 expires.

[0194] When an NG interface is in an NG Suspend state, how WAB-gNB and AMF process the context of the NG interface is also a problem that needs to be solved.

[0195] FIGs. 15A-15D show an example of a context of an NG interface according to embodiments of the present disclosure. When the WAB-gNB establishes an NG interface with the AMF, the context of the NG interface as shown in FIGs. 15A-15D will be established. Regarding how to process the context of the NG interface in an NG Suspend state, the present disclosure proposes the following methods:

[0196] do not release any NG interface context or related information, i.e., reserve all NG interface context or related information;

[0197] release (or delete) related information of all IEs whose 'Presence' attribute is 'optional';

[0198] reserve related information of all IEs whose 'Presence' attribute is 'mandatory';

[0199] release related information of IEs that change frequently and / or IEs that may change, e.g., one or more of the following IEs: supported Timing Advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging DRX, etc.; and

[0200] reserve related information of IEs that change infrequently and / or IEs that do not change, e.g., one or more of the following IEs: node identifier (e.g., global RAN node ID, etc.), RAN node name, extended RAN node name, etc.

[0201] In addition to the above-mentioned predetermined methods, dynamic indication methods can also be used to exchange NG context related information that needs to be reserved or released.

[0202] For example, the WAB-gNB may also add eleventh information in the NG suspend request, and the eleventh information may indicate to the AMF at least one of the following: NG contexts (or IEs) that the AMF can release, NG contexts (or IEs) that the AMF cannot release, NG contexts (or IEs) that the WAB-gNB expects (or suggests) to release, NG contexts (or IEs) that the WAB-gNB does not expect (or suggest) to release, etc.;

[0203] The AMF may also add twelfth information in the NG suspend response, and the twelfth information may indicate to the WAB-gNB of NG contexts (or IEs) that the AMF agrees to release, and / or NG contexts (or IEs) that the AMF rejects to release, etc.;

[0204] The twelfth information may also indicate to the WAB-gNB that: it is agreed to release all the NG contexts indicated by the WAB-gNB in the eleventh information, and / or it is not agreed to release all the NG contexts indicated by the WAB-gNB in the eleventh information.

[0205] One or more of the above various methods can be used in combination with each other, which is not limited herein.

[0206] When an NG interface is in an NG Suspend state, if the WAB-gNB expects to resume the connection of the NG interface, the context of the NG interface needs to be resumed. FIG. 15E shows an example procedure for context resume for an NG interface according to embodiments of the present disclosure.

[0207] As shown in FIG. 15E, when the WAB-gNB expects to recover from an NG Suspend state to an NG Connection state, it may transmit an NG resume request message to the AMF and add thirteenth information in the message. The thirteenth information may be information for indicating to resume the NG interface context, which may include information on the NG interface context that needs to be resumed. The NG interface context that needs to be resumed may include at least one of the following:

[0208] all the NG context content (i.e., all IEs in the NG context);

[0209] IEs that are released and / or IEs whose 'Presence' attribute is 'optional';

[0210] IEs that are changed and / or IEs whose 'Presence' attribute is 'mandatory';

[0211] IEs that change frequently, e.g., one or more of the following IEs: supported TA list, default paging DRX, UE retention information, Narrow Band Internet of Things (NB-IoT) default paging DRX, etc.;

[0212] NG context that the AMF needs to release as indicated in the eleventh information;

[0213] NG context in the eleventh information that the WAB-gNB agrees to release as indicated in the twelfth information;

[0214] NG context that the WAB-gNB agrees to release as indicated in the twelfth information.

[0215] The thirteenth information may be the complete NG context content that needs to be transmitted by the WAB-gNB, or may be delta information, that is, the difference between the NG context reserved in the NG Suspend state and the NG context that needs to be resumed during NG resuming. For example, assuming that a certain IE is reserved or not released in the NG Suspend state, but when NG resuming is required, the value of the IE changes compared to when the NG is suspended. In this case, the WAB-gNB can only transmit the delta information (for example, difference value) of this IE between when the NG is resumed and when the NG is suspended.

[0216] The third aspect: impact of transmissions between WAB-MT and BH gNB on UEs served by WAB-gNB

[0217] The data of a UE served by the WAB-gNB needs to be transmitted through the BH PDU session established between the WAB-MT and the BH gNB, so the amount of air interface resources allocated by the BH gNB to the WAB-MT may directly affect the data transmission between the WAB-gNB and the UE it serves. Therefore, corresponding enhancements need to be made to allow the BH gNB to allocate sufficient resources to the WAB-MT to ensure data transmission between the WAB-gNB and the UE it serves.

[0218] FIG. 16A shows an example procedure for transmitting assistance information to a BH gNB over a Uu interface according to embodiments of the present disclosure. As shown in FIG. 16A:

[0219] The WAB-MT transmits a seventh message to the BH gNB. The seventh message may be an RRC message and contain at least one of the following information:

[0220] information of a request for the BH gNB to allocate (more) resources to the WAB-MT;

[0221] the number of UEs served by the WAB-gNB;

[0222] the traffic profile of the UEs served by the WAB-gNB;

[0223] the amount of resources expected by the WAB-gNB; and

[0224] the ID of the co-located WAB-gNB.

[0225] After receiving the seventh message, the BH gNB may reply to the WAB-MT with an eighth message, which may be an RRC message, such as an RRC reconfiguration message, or other RRC messages, which are not limited in the present disclosure. The eighth message may be used to indicate time-frequency domain resources allocated for the WAB-MT.

[0226] FIG. 16B shows another example procedure for transmitting assistance information to a BH gNB over a Uu interface according to embodiments of the present disclosure. As shown in FIG. 16B:

[0227] After the WAB-gNB and the BH gNB have established an Xn interface, the WAB-gNB may transmit a ninth message to the BH gNB. The ninth message may be a message on the Xn interface. The ninth message may include at least one of the following information:

[0228] information of a request for the BH gNB to allocate (more) resources to the WAB-MT;

[0229] the number of UEs served by the WAB-gNB;

[0230] the traffic profile of the UEs served by the WAB-gNB;

[0231] the amount of resources expected by the WAB-gNB; and

[0232] the ID of the co-located WAB-MT.

[0233] After receiving the ninth message, the BH gNB may reply to the WAB-gNB with a tenth message, which may include information indicating at least one of the following:

[0234] resources and / or the amount of resources to be allocated to the WAB-MT;

[0235] the acceptation or rejection of the request for (more) resources by the WAB-gNB.

[0236] After the BH gNB transmits the tenth message to the WAB-gNB, if it agrees with the WAB-gNB's request for (more) resources, it may allocate corresponding resources to the WAB-MT.

[0237] In the example procedures of FIG. 16A and FIG. 16B shown above, the methods for requesting resources can further be divided into the following two methods:

[0238] the first method: the amount of resources expected by the WAB-gNB in the seventh message and the ninth message is the amount of all required resources;

[0239] the second method: the amount of resources expected by the WAB-gNB in the seventh message and the ninth message may be indicated to the BH gNB per BH PDU session, as shown in FIG. 17.

[0240] For example, BH PDU session IDs 1 and 2 are used to transmit Xn traffic and NG traffic respectively, and the corresponding expected amount of resources may also vary according to the different BH PDU session IDs.

[0241] The BH gNB may configure corresponding resources for WAB-MT according to different BH PDU sessions.

[0242] As mentioned above, the data of the UE served by the WAB-gNB needs to be transmitted through the BH PDU session established between the WAB-MT and the BH gNB, so the signal quality of the Uu interface between the BH gNB and the WAB-MT will also directly affects the data transmission between the WAB-gNB and the UE it serves. Therefore, corresponding enhancements are required so that when the air interface signal quality of the WAB-MT is bad, the BH gNB can timely hand over the WAB-MT to a target BH gNB with a good signal quality.

[0243] An implementation may be to use a higher reference signal received power (RSRP) threshold and / or a higher reference signal received quality (RSRQ) threshold (than that of a normal UE) when the WAB-MT performs cell selection, cell reselection or cell handover, so that the WAB-MT can be served by a cell with better signal quality. The details are as follows.

[0244] As for cell selection: when the WAB-MT is in an idle state, a new offset (e.g., a first offset, or offset1) may be introduced for the WAB-MT. That is, the first offset can be applied to the WAB-MT only and not to a normal UE. The first offset may be informed to the WAB-MT through cell broadcast information (SIB message). After receiving the first offset, the WAB-MT may use it to determine whether a specific cell meets the cell selection criterion (for example, S criterion):

[0245] Srxlev (Cell selection RX level value (dB)) = Srxlev + offset1

[0246] Squal (Cell selection quality value (dB)) = Squal+offset1.

[0247] As mentioned above, since the Srxlev or Squal for the WAB-MT is added with an offset (the offset may be a positive value) when compared with that for a normal UE, a cell with a better quality will be selected when compared with a normal UE.

[0248] As for cell reselection: when the WAB-MT performs cell reselection, a new offset (for example, a second offset, or offset2) may be introduced for the WAB-MT. That is, the second offset can also be applied to WAB-MT only and not to a normal UE. The second offset may be informed to the WAB-MT through cell broadcast information (SIB message) or an RRC message (e.g., RRC release message):

[0249] Rs = Rs + offset2 (Rs: cell-ranking criterion for serving cell)

[0250] Rn = Rn+offset2 (Rn: cell-ranking criterion for neighbouring cells)

[0251] As described above, since the Rs or Rn for the WAB-MT is added with an offset (the offset may be a positive value) when compared with that for a normal UE, a cell with a better quality will be selected when compared with a normal UE.

[0252] As for cell handover: the source BH gNB may configure measurement configuration for the WAB-MT, so that the WAB-MT can perform frequency measurement and report it to the source BH gNB, which may be used by the source BH gNB as a reference and to perform cell handover for the WAB-MT. Therefore, a new offset (for example, a third offset, or offset3) may be introduced for the WAB-MT. That is, the third offset can also be applied to WAB-MT only and not to a normal UE. The third offset may be informed to the WAB-MT through cell broadcast information (SIB message) or an RRC message (e.g., RRC reconfiguration message):

[0253] RSRP / RSRQ reported = RSRP / RSRQ measured - offset3

[0254] According to the above equation, the reported RSRP / RSRQ value would be smaller than the actual measured RSRP / RSRQ value, so the source BH gNB can hand over the WAB-MT to a better cell in advance.

[0255] The offset3 may be a fixed value (the offset may be a positive value) or a variable value that varies within a certain range.

[0256] Another implementation may be based on the implementation of the BH gNB. The specific process is as follows.

[0257] The WAB-MT may inform the BH gNB that it is a WAB-MT or WAB node through an RRC message (e.g., Msg5, or other RRC message).

[0258] After the BH gNB knows that it is a WAB-MT or WAB node, the BH gNB may guarantee the connection quality of the Uu interface between the BH gNB and the WAB-MT through its implementation.

[0259] Another implementation may be by means of reporting assistance information to the BH gNB by the WAB-MT. The specific process is as follows:

[0260] When the connection quality of the Uu interface between the BH gNB and the WAB-MT is not good enough to guarantee the service quality of the WAB-gNB to the UE it serves, the WAB-MT can know this situation. In this case, the WAB-MT may actively transmit an eleventh message to the BH gNB, which may include fourteenth information.

[0261] The eleventh message may be UE assistance information or other RRC messages, which are not limited herein.

[0262] The fourteenth information may include at least one of the following:

[0263] information for indicating the BH gNB to perform a cell handover operation for the WAB-MT;

[0264] information for indicating to the BH gNB that the WAB-MT expects a cell handover operation;

[0265] ID of a cell to which the WAB-MT expects to handover;

[0266] the amount of resources that the WAB-MT expects the target BH gNB to be able to allocate;

[0267] the amount of resources that the WAB-MT expects the target BH gNB to be able to allocate for a certain BH PDU session ID, and the ID of the BH PDU session.

[0268] It should be understood that, depending on the application scenarios, the various example aspects, methods, steps, procedures, etc. shown above in conjunction with the drawings can be implemented individually or combined in any manner, which is not limited herein.

[0269] Next, FIG. 18 shows a flowchart of a method 1800 performed by a wireless access backhaul (WAB)-gNB in a wireless communication system according to embodiments of the present disclosure.

[0270] As shown in FIG. 18, a method 1800 performed by a WAB-gNB in a wireless communication system according to embodiments of the present disclosure may include: in step S1801, transmitting a first message to a second node, wherein the first message is associated with a request to suspend an NG interface between the WAB-gNB and the second node; and in step S1802, receiving a message in response to the request from the second node. In some implementations, the first message includes at least one of: first time information related to a time for suspending the NG interface, first history location information of the WAB-gNB, second history location information of a co-located wireless access backhaul-mobile terminal (WAB-MT) of the WAB-gNB, information related to a context of the NG interface that the WAB-gNB suggests to release, information related to a context of the NG interface that the WAB-gNB does not suggest to release. In some implementations, the message includes at least one of: second time information related to a time for suspending the NG interface, and third time information related to a time for disabling a suspend request for the NG interface.

[0271] According to embodiments of the present disclosure, the message is a second message related to the request being accepted, wherein the second message includes second time information related to a time for suspending the NG interface.

[0272] According to embodiments of the present disclosure, the message is a third message, wherein the third message includes at least one of: a first cause value related to the request being rejected, third time information related to a time for disabling a suspend request for the NG interface, wherein in a case that the third message includes the first cause value, the method further includes: transmitting an NG removal request related to the NG interface to the second node and / or performing a removal operation related to the NG interface.

[0273] According to embodiments of the present disclosure, the method further includes: transmitting an NG removal request message related to the NG interface to a third node, wherein the NG removal request message includes name information of the second node and an identifier of the WAB-gNB, wherein the identifier of the WAB-gNB is transmitted by the third node to the second node.

[0274] According to embodiments of the present disclosure, the method further includes: receiving an NG removal response message from the third node, wherein the NG removal response message includes the name information of the second node, wherein the name information of the second node is transmitted by the second node to the third node.

[0275] According to embodiments of the present disclosure, the context of the NG interface that the WAB-gNB suggests to release includes at least one of: information element (IE) whose presence attribute is optional, information element (IE) that changes frequently, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX); and wherein the context of the NG interface that the WAB-gNB does not suggest to release includes at least one of: all information elements (IEs) in the context of the NG interface, information element (IE) whose presence attribute is mandatory, information element (IE) that changes infrequently, global RAN node identifier, RAN node name, extended RAN node name.

[0276] According to embodiments of the present disclosure, the second message further includes at least one of: information related to a context of the NG interface that the second node agrees to release, and information related to a context of the NG interface that the second node does not agree to release.

[0277] According to embodiments of the present disclosure, the method further includes: transmitting a fourth message to the second node, wherein the fourth message is associated with a request to resume the NG interface, wherein the fourth message includes information related to resuming a context of the NG interface.

[0278] According to embodiments of the present disclosure, the context of the NG interface resumed includes at least one of: all information elements (IEs) in the context of the NG interface, IE that is released in the context of the NG interface, IE that is changed and with a presence attribute of mandatory in the context of the NG interface, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX), delta information of changed information elements (IEs).

[0279] FIG. 19 shows a flowchart of a method 1900 performed by a second node in a wireless communication system according to embodiments of the present disclosure.

[0280] As shown in FIG. 19, the method 1900 performed by a second node in a wireless communication system according to embodiments of the present disclosure may include: in step S1901, receiving a first message from a Wireless Access Backhaul (WAB)-gNB, wherein the first message is associated with a request to suspend an NG interface between the WAB-gNB and the second node; and in step S1902, transmitting a message in response to the request to the WAB-gNB. In some implementations, the first message includes at least one of: first time information related to a time for suspending the NG interface, first history location information of the WAB-gNB, second history location information of a co-located wireless access backhaul-mobile terminal (WAB-MT) of the WAB-gNB, information related to a context of the NG interface that the WAB-gNB suggests to release, information related to a context of the NG interface that the WAB-gNB does not suggest to release. In some implementations, the message includes at least one of: second time information related to a time for suspending the NG interface, and third time information related to a time for disabling a suspend request for the NG interface.

[0281] According to embodiments of the present disclosure, the message is a second message related to the request being accepted, wherein the second message includes second time information related to a time for suspending the NG interface.

[0282] According to embodiments of the present disclosure, the message is a third message, wherein the third message includes at least one of: a first cause value related to the request being rejected, third time information related to a time for disabling a suspend request for the NG interface, wherein in a case that the third message includes the first cause value, the method further includes: receiving an NG removal request related to the NG interface from the WAB-gNB and / or performing a removal operation related to the NG interface.

[0283] According to embodiments of the present disclosure, the method further includes: receiving an identifier of the WAB-gNB from a third node, wherein an NG removal request message related to the NG interface is transmitted from the WAB-gNB to the third node, wherein the NG removal request message includes name information of the second node and an identifier of the WAB-gNB.

[0284] According to embodiments of the present disclosure, the method further includes: transmitting an NG removal response message to the third node, wherein the NG removal response message includes the name information of the second node and an identifier of the WAB-gNB, wherein the name information of the second node is transmitted by the third node to the WAB-gNB.

[0285] According to embodiments of the present disclosure, the context of the NG interface that the WAB-gNB suggests to release includes at least one of: information element (IE) whose presence attribute is optional, information element (IE) that changes frequently, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX); and wherein the context of the NG interface that the WAB-gNB does not suggest to release includes at least one of: all information elements (IEs) in the context of the NG interface, information element (IE) whose presence attribute is mandatory, information element (IE) that changes infrequently, global RAN node identifier, RAN node name, extended RAN node name.

[0286] According to embodiments of the present disclosure, the second message further includes at least one of: information related to a context of the NG interface that the second node agrees to release, and information related to a context of the NG interface that the second node does not agree to release.

[0287] According to embodiments of the present disclosure, the method further includes: receiving a fourth message from the WAB-gNB, wherein the fourth message is associated with a request to resume the NG interface, wherein the fourth message includes information related to resuming a context of the NG interface.

[0288] According to embodiments of the present disclosure, the context of the NG interface resumed includes at least one of: all information elements (IEs) in the context of the NG interface, IE that is released in the context of the NG interface, IE that is changed and with a presence attribute of mandatory in the context of the NG interface, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX), delta information of changed information elements (IEs).

[0289] FIG. 20 shows a flowchart of a method 2000 performed by a wireless access backhaul-mobile terminal (WAB-MT) in a wireless communication system according to embodiments of the present disclosure.

[0290] As shown in FIG. 20, the method 2000 performed by a WAB-MT in a wireless communication system according to embodiments of the present disclosure may include: in step S2001, receiving a first message from a Wireless Access Backhaul (WAB)-gNB, wherein the first message is associated with a request to suspend an NG interface between the WAB-gNB and a second node; in step S2002, transmitting the first message to the second node; and in step S2003, receiving a message in response to the request from the second node. In some implementations, the first message includes at least one of: first time information related to a time for suspending the NG interface, first history location information of the WAB-gNB, second history location information of a co-located wireless access backhaul-mobile terminal (WAB-MT) of the WAB-gNB, information related to a context of the NG interface that the WAB-gNB suggests to release, information related to a context of the NG interface that the WAB-gNB does not suggest to release. In some implementations, the message includes at least one of: second time information related to a time for suspending the NG interface, and third time information related to a time for disabling a suspend request for the NG interface.

[0291] According to embodiments of the present disclosure, the message is a second message related to the request being accepted, wherein the second message includes second time information related to a time for suspending the NG interface.

[0292] According to embodiments of the present disclosure, the message is a third message, wherein the third message includes at least one of: a first cause value related to the request being rejected, third time information related to a time for disabling a suspend request for the NG interface, wherein in a case that the third message includes the first cause value, the method further includes: receiving an NG removal request related to the NG interface from the WAB-gNB; and transmitting an NG removal request related to the NG interface to the second node.

[0293] According to embodiments of the present disclosure, the method further includes: receiving an NG removal request message related to the NG interface from the WAB-gNB; and transmitting the NG removal request message to a third node, wherein the NG removal request message includes name information of the second node and an identifier of the WAB-gNB, wherein the identifier of the WAB-gNB is transmitted by the third node to the second node.

[0294] According to embodiments of the present disclosure, the method further includes: receiving an NG removal response message from the third node; and transmitting the NG removal response message to the WAB-gNB, wherein the NG removal response message includes the name information of the second node, wherein the name information of the second node is transmitted by the second node to the third node.

[0295] According to embodiments of the present disclosure, the context of the NG interface that the WAB-gNB suggests to release includes at least one of: information element (IE) whose presence attribute is optional, information element (IE) that changes frequently, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX); and wherein the context of the NG interface that the WAB-gNB does not suggest to release includes at least one of: all information elements (IEs) in the context of the NG interface, information element (IE) whose presence attribute is mandatory, information element (IE) that changes infrequently, global RAN node identifier, RAN node name, extended RAN node name.

[0296] According to embodiments of the present disclosure, the second message further includes at least one of: information related to a context of the NG interface that the second node agrees to release, and information related to a context of the NG interface that the second node does not agree to release.

[0297] According to embodiments of the present disclosure, the method further includes: receiving a fourth message from the WAB-gNB; and transmitting the fourth message to the second node, wherein the fourth message is associated with a request to resume the NG interface, wherein the fourth message includes information related to resuming a context of the NG interface.

[0298] According to embodiments of the present disclosure, the context of the NG interface resumed includes at least one of: all information elements (IEs) in the context of the NG interface, IE that is released in the context of the NG interface, IE that is changed and with a presence attribute of mandatory in the context of the NG interface, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX), delta information of changed information elements (IEs).

[0299] It should be understood that methods 1800, 1900, 2000, etc. according to embodiments of the present disclosure may also include one or more of the methods or steps described above in conjunction with any example, aspect or drawing, which will not be described again here.

[0300] Next, FIG. 21 shows a schematic diagram of a node 2100 in a wireless communication system according to embodiments of the present disclosure.

[0301] As shown in FIG. 21, a node 2100 (e.g., which may be the second node as described above) according to embodiments of the present disclosure may include a transceiver 2110 and a processor 2120. The transceiver 2110 may be configured to transmit and receive signals. The processor 2120 may be coupled to the transceiver 2110 and may be configured to (e.g., control the transceiver 2110 to) perform any method performed by a second node or the like in a wireless communication system according to embodiments of the present disclosure. Herein, the second node may include any core network node, such as an AMF or the like as described above.

[0302] Herein, a node may also be referred to as a node device. Herein, a processor may also be referred to as a controller.

[0303] FIG. 22 shows a schematic diagram of a WAB-gNB 2200 in a wireless communication system according to embodiments of the present disclosure.

[0304] As shown in FIG. 22, a WAB-gNB 2200 according to embodiments of the present disclosure may include a transceiver 2210 and a processor 2220. The transceiver 2210 may be configured to transmit and receive signals. The processor 2220 may be coupled to the transceiver 2210 and may be configured to (e.g., control the transceiver 2210 to) perform any method performed by a WAB-gNB in a wireless communication system according to embodiments of the present disclosure.

[0305] FIG. 23 shows a schematic diagram of a WAB-MT 2300 in a wireless communication system according to embodiments of the present disclosure.

[0306] As shown in FIG. 23, the WAB-MT 2300 according to embodiments of the present disclosure may include a transceiver 2310 and a processor 2320. The transceiver 2310 may be configured to transmit and receive signals. The processor 2320 may be coupled to the transceiver 2310 and may be configured to (e.g., control the transceiver 2310 to) perform any method performed by a WAB-MT in a wireless communication system according to embodiments of the present disclosure.

[0307] Embodiments of the present disclosure further provide a computer-readable medium having computer-readable instructions stored thereon, which when executed by a processor can be used to implement any method according to embodiments of the present disclosure.

[0308] Various embodiments of the present disclosure may be implemented as computer-readable codes embodied on a computer-readable recording medium from a specific perspective. A computer-readable recording medium is any data storage device that can store data readable by a computer system. Examples of computer-readable recording media may include read-only memory (ROM), random access memory (RAM), compact disk read-only memory (CD-ROM), magnetic tape, floppy disk, optical data storage device, carrier wave (e.g., data transmission via the Internet), etc. Computer-readable recording media can be distributed by computer systems connected via a network, and thus computer-readable codes can be stored and executed in a distributed manner. Furthermore, functional programs, codes and code segments for implementing various embodiments of the present disclosure can be easily explained by those skilled in the art to which embodiments of the present disclosure are applied.

[0309] It will be understood that embodiments of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software. The software may be stored as program indications or computer-readable codes executable on a processor on a non-transitory computer-readable medium. Examples of non-transitory computer-readable recording media include magnetic storage media (such as ROM, floppy disk, hard disk, etc.) and optical recording media (such as CD-ROM, digital video disk (DVD), etc.). Non-transitory computer-readable recording media may also be distributed on computer systems coupled to a network, so that computer-readable codes are stored and executed in a distributed manner. The medium can be read by a computer, stored in a memory, and executed by a processor. Various embodiments may be implemented by a computer or a portable terminal including a controller and a memory, and the memory may be an example of a non-transitory computer-readable recording medium suitable for storing program (s) with indications for implementing embodiments of the present disclosure. The present disclosure may be realized by a program with code for concretely implementing the apparatus and method described in the claims, which is stored in a machine (or computer)-readable storage medium. The program may be electronically carried on any medium, such as a communication signal transmitted via a wired or wireless connection, and the present disclosure suitably includes its equivalents.

[0310] What has been described above is only the specific implementation of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Anyone who is familiar with this technical field may make various changes or substitutions within the technical scope disclosed in the present disclosure, and these changes or substitutions should be covered within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1.A method performed by a Wireless Access Backhaul (WAB)-gNB in a wireless communication system, comprising:transmitting a first message to a second node, wherein the first message is associated with a request to suspend an NG interface between the WAB-gNB and the second node; andreceiving a message in response to the request from the second node,wherein the first message comprises at least one of:first time information related to a time for suspending the NG interface, first history location information of the WAB-gNB, second history location information of a co-located wireless access backhaul-mobile terminal (WAB-MT) of the WAB-gNB, information related to a context of the NG interface that the WAB-gNB suggests to release, information related to a context of the NG interface that the WAB-gNB does not suggest to release;wherein the first time information indicates to the second node a time duration during which the NG interface is to be suspended;wherein the message is a second message related to the request being accepted;wherein the second message comprises second time information related to a time for suspending the NG interface; andwherein the second time information indicates that the second node is to perform an NG removal procedure, after the time represented by the second time information.2.The method of claim 1, further comprising:transmitting an NG removal request message related to the NG interface to a third node, wherein the NG removal request message comprises name information of the second node and an identifier of the WAB-gNB, wherein the identifier of the WAB-gNB is transmitted by the third node to the second node; andreceiving an NG removal response message from the third node, wherein the NG removal response message comprises the name information of the second node, wherein the name information of the second node is transmitted by the second node to the third node.3.The method of claim 1,wherein the context of the NG interface that the WAB-gNB suggests to release comprises at least one of:an information element (IE) whose presence attribute is optional, an information element (IE) that changes frequently, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX);wherein the context of the NG interface that the WAB-gNB does not suggest to release comprises at least one of:all information elements (IEs) in the context of the NG interface, an information element (IE) whose presence attribute is mandatory, an information element (IE) that changes infrequently, global RAN node identifier, RAN node name, extended RAN node name; andwherein the second message further comprises at least one of:information related to the context of the NG interface that the second node agrees to release, and information related to the context of the NG interface that the second node does not agree to release.4.The method of claim 1, further comprising:transmitting a fourth message to the second node, wherein the fourth message is associated with a request to resume the NG interface,wherein the fourth message comprises information related to resuming the context of the NG interface; andwherein the context of the NG interface resumed comprises at least one of:all information elements (IEs) in the context of the NG interface, an IE that is released in the context of the NG interface, an IE that is changed and with a presence attribute of mandatory in the context of the NG interface, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX), delta information of changed information elements (IEs).5.A method performed by a second node in a wireless communication system, comprising:receiving a first message from a Wireless Access Backhaul (WAB)-gNB, wherein the first message is associated with a request to suspend an NG interface between the WAB-gNB and the second node; andtransmitting a message in response to the request to the WAB-gNB,wherein the first message comprises at least one of:first time information related to a time for suspending the NG interface, first history location information of the WAB-gNB, second history location information of a co-located wireless access backhaul-mobile terminal (WAB-MT) of the WAB-gNB, information related to a context of the NG interface that the WAB-gNB suggests to release, information related to a context of the NG interface that the WAB-gNB does not suggest to release;wherein the first time information indicates to the second node a time duration during which the NG interface is to be suspended;wherein the message is a second message related to the request being accepted;wherein the second message comprises second time information related to a time for suspending the NG interface; andwherein the second time information indicates that the second node is to perform an NG removal procedure, after the time represented by the second time information.6.The method of claim 5, further comprising:receiving an identifier of the WAB-gNB from a third node, wherein an NG removal request message related to the NG interface is transmitted from the WAB-gNB to the third node, wherein the NG removal request message comprises name information of the second node and an identifier of the WAB-gNB; andtransmitting an NG removal response message to the third node, wherein the NG removal response message comprises the name information of the second node and the identifier of the WAB-gNB, wherein the name information of the second node is transmitted by the third node to the WAB-gNB.7.The method of claim 5,wherein the context of the NG interface that the WAB-gNB suggests to release comprises at least one of:an information element (IE) whose presence attribute is optional, an information element (IE) that changes frequently, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX);wherein the context of the NG interface that the WAB-gNB does not suggest to release comprises at least one of:all information elements (IEs) in the context of the NG interface, an information element (IE) whose presence attribute is mandatory, an information element (IE) that changes infrequently, global RAN node identifier, RAN node name, extended RAN node name; andwherein the second message further comprises at least one of:information related to the context of the NG interface that the second node agrees to release, and information related to the context of the NG interface that the second node does not agree to release.8.The method of claim 5, further comprising:receiving a fourth message from the WAB-gNB, wherein the fourth message is associated with a request to resume the NG interface,wherein the fourth message comprises information related to resuming the context of the NG interface; andwherein the context of the NG interface resumed comprises at least one of:all information elements (IEs) in the context of the NG interface, an IE that is released in the context of the NG interface, an IE that is changed and with a presence attribute of mandatory in the context of the NG interface, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX), delta information of changed information elements (IEs).9.A Wireless Access Backhaul (WAB)-gNB in a wireless communication system, the WAB-gNB comprising:a processor; anda transceiver, coupled with the processor, configured to:transmit a first message to a second node, wherein the first message is associated with a request to suspend an NG interface between the WAB-gNB and the second node; andreceive a message in response to the request from the second node,wherein the first message comprises at least one of:first time information related to a time for suspending the NG interface, first history location information of the WAB-gNB, second history location information of a co-located wireless access backhaul-mobile terminal (WAB-MT) of the WAB-gNB, information related to a context of the NG interface that the WAB-gNB suggests to release, information related to a context of the NG interface that the WAB-gNB does not suggest to release;wherein the first time information indicates to the second node a time duration during which the NG interface is to be suspended;wherein the message is a second message related to the request being accepted;wherein the second message comprises second time information related to a time for suspending the NG interface; andwherein the second time information indicates that the second node is to perform an NG removal procedure, after the time represented by the second time information.10.The WAB-gNB as claimed in claim 9, wherein the transceiver is configured to;transmit an NG removal request message related to the NG interface to a third node, wherein the NG removal request message comprises name information of the second node and an identifier of the WAB-gNB, wherein the identifier of the WAB-gNB is transmitted by the third node to the second node; andreceive an NG removal response message from the third node, wherein the NG removal response message comprises the name information of the second node, wherein the name information of the second node is transmitted by the second node to the third node.11.The WAB-gNB as claimed in claim 9,wherein the context of the NG interface that the WAB-gNB suggests to release comprises at least one of:an information element (IE) whose presence attribute is optional, an information element (IE) that changes frequently, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX);wherein the context of the NG interface that the WAB-gNB does not suggest to release comprises at least one of:all information elements (IEs) in the context of the NG interface, an information element (IE) whose presence attribute is mandatory, an information element (IE) that changes infrequently, global RAN node identifier, RAN node name, extended RAN node name; andwherein the second message further comprises at least one of:information related to the context of the NG interface that the second node agrees to release, and information related to the context of the NG interface that the second node does not agree to release.12.The WAB-gNB as claimed in claim 9, wherein the transceiver is configured to;transmit a fourth message to the second node, wherein the fourth message is associated with a request to resume the NG interface,wherein the fourth message comprises information related to resuming the context of the NG interface; andwherein the context of the NG interface resumed comprises at least one of:all information elements (IEs) in the context of the NG interface, an IE that is released in the context of the NG interface, an IE that is changed and with a presence attribute of mandatory in the context of the NG interface, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX), delta information of changed information elements (IEs).13.A second node in a wireless communication system, the second node comprising:a processor; anda transceiver; coupled with the processor, configured to:receive a first message from a Wireless Access Backhaul (WAB)-gNB, wherein the first message is associated with a request to suspend an NG interface between the WAB-gNB and the second node; andtransmit a message in response to the request to the WAB-gNB,wherein the first message comprises at least one of:first time information related to a time for suspending the NG interface, first history location information of the WAB-gNB, second history location information of a co-located wireless access backhaul-mobile terminal (WAB-MT) of the WAB-gNB, information related to a context of the NG interface that the WAB-gNB suggests to release, information related to a context of the NG interface that the WAB-gNB does not suggest to release;wherein the first time information indicates to the second node a time duration during which the NG interface is to be suspended;wherein the message is a second message related to the request being accepted;wherein the second message comprises second time information related to a time for suspending the NG interface; andwherein the second time information indicates that the second node is to perform an NG removal procedure, after the time represented by the second time information.14.The second node as claimed in claim 13, wherein the transceiver is configured to;receive an identifier of the WAB-gNB from a third node, wherein an NG removal request message related to the NG interface is transmitted from the WAB-gNB to the third node, wherein the NG removal request message comprises name information of the second node and an identifier of the WAB-gNB; andtransmit an NG removal response message to the third node, wherein the NG removal response message comprises the name information of the second node and the identifier of the WAB-gNB, wherein the name information of the second node is transmitted by the third node to the WAB-gNB.15.The second node as claimed in claim 13, wherein the transceiver is configured to;receive a fourth message from the WAB-gNB, wherein the fourth message is associated with a request to resume the NG interface,wherein the context of the NG interface that the WAB-gNB suggests to release comprises at least one of:an information element (IE) whose presence attribute is optional, an information element (IE) that changes frequently, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX);wherein the context of the NG interface that the WAB-gNB does not suggest to release comprises at least one of:all information elements (IEs) in the context of the NG interface, an information element (IE) whose presence attribute is mandatory, an information element (IE) that changes infrequently, global RAN node identifier, RAN node name, extended RAN node name;wherein the second message further comprises at least one of:information related to the context of the NG interface that the second node agrees to release, and information related to the context of the NG interface that the second node does not agree to release;wherein the fourth message comprises information related to resuming the context of the NG interface; andwherein the context of the NG interface resumed comprises at least one of:all information elements (IEs) in the context of the NG interface, an IE that is released in the context of the NG interface, an IE that is changed and with a presence attribute of mandatory in the context of the NG interface, a supported timing advance (TA) list, default paging discontinuous reception (DRX), UE retention information, Narrow Band Internet of Things (NB-IoT) default paging discontinuous reception (DRX), delta information of changed information elements (IEs).

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