Managing NG interface at a radio access network node

Abstract

A method for use in managing connectivity of a radio access network, RAN, node, connectable to an access and mobility management function, AMF, entity of a core network via a Next Generation, NG, interface, the method at the AMF entity comprising: receiving, from the RAN node, a request to suspend, resume or remove the NG interface; accepting or rejecting the request; and, in the case of accepting the request, suspending, resuming or removing the NG interface based on the request. The method may alternatively be performed at the RAN node.

Description

[0001] 11031371W001 MANAGING NG INTERFACE AT A RADIO ACCESS NETWORK NODE

[0002] FIELD OF THE INVENTION

[0003] The present invention generally relates to methods for use in managing authorization of a mobile Wireless Access Backhaul (WAB) node of a wireless communication system. For example, the disclosure relates to methods for use in a process for managing the mobility of nodes of a wireless communication system involving at least one mobile Wireless Access Backhaul, WAB, nodes.

[0004] BACKGROUND

[0005] Wireless communication systems are largely deployed to address a wide range of applications, from mobile broadband, massive machine type communications to Ultra Reliable Low Latency Communications (URLLC). Such systems allow a plurality of user equipment (UE) or mobile terminals to share the wireless medium to exchange several types of data content (e.g. video, voice, messaging ...) over a radio access network (RAN) through one or more base stations (gNBs). The base stations are conventionally wired-connected (e.g. through fiber) to a core network, forming an intermediate network, named backhaul (BH).

[0006] Examples of such wireless multiple-access communication systems include systems based on 3rd generation partnership project (3GPP - RTM) standards, such as fourth-generation (4G) Long Term Evolution (LTE) or recent fifth-generation (5G) New Radio (NR) systems, or systems-based IEEE 802.11 standards, such as WiFi.

[0007] The demand for network densification increases due to the rising number of users and higher throughput requirement.

[0008] Facing the issues of high deployment costs and time of the wired backhaul networks with network densification, 3GPP has proposed, from release 16 for 5G NR, a wireless backhaul, also known as Integrated Access and Backhaul, IAB, where part of the wireless (i.e. radio) spectrum is used for the backhaul connection of base stations instead of fiber. The wireless backhaul communications (between base stations) may use the same radio resources as access communications (between a base station and UEs).

[0009] IAB turns out to be a competitive alternative to the fiber-based backhauling in dense areas or areas difficult to cover, as it allows scalable and rapid installations without the burden of cabling the base stations.

[0010] IAB is most likely to operate in the millimeter wave (mmWave) band to achieve the required Gbps (gigabits per second) data rate.11031371W001 Urban environments are usually characterised by a high density of users along with the presence of a significant number of vehicles (e.g. public / private passengers transportation, goods delivery, food trucks ...). The speed of some of the vehicles may be pretty low or at least similar to pedestrian speed and some of these vehicles may even be temporarily stationary. Some of these vehicles (e.g. buses, trains or trams), may have predictable routes and / or limited mobility areas (e.g. some vehicles, such as food trucks or promotional vehicles, may be located outside stadiums or show venues) while others may have predictable stationary locations (e.g. taxis).

[0011] 3GPP is considering that such vehicles could offer an opportunity to increase network coverage and connectivity to the UEs inside the vehicles, or even to UEs in proximity to the vehicles, by installing on these vehicles on-board base stations (or base station elements) that would act as relays. These relays would rely on 5G wireless backhaul (typically IAB, or Integrated Access & Backhaul) for connecting to a fixed donor device. Thus, based upon the fixed IAB foundations set out in Releases 16 and 17, 3GPP is now considering mobile IAB systems and architecture, as a part of the Release 18 framework, in order to address scenarios focusing on mobile lAB-nodes mounted on vehicles (for example, a bus, a train, a taxi). In such scenarios, mobile lAB-nodes can also be referred to as Vehicle Mounted Relays (VMR), providing 5G coverage / capacity to on-board and / or surrounding UEs. The technical benefits of using vehicle relays include, among others, the ability of the relay vehicle to get better coverage than the nearby UE, thanks to better RF / antenna capabilities, thus providing the UE with a better link to the macro network. Additionally, a vehicle relay is expected to have less stringent power / battery constraints than the UEs.

[0012] Some enhancements further considered by 3GPP for Release 19, consider the need for 5G access for UEs onboard aircrafts, cruise ships, helicopters and vehicles in remote areas with limited sky visibility (e.g. where terrestrial cellular coverage or Wi-Fi coverage is not available), support for onboard / on-site mobile edge computing (MEC), local services, and direct local inter-UE communications, or local gNB deployment in public safety or disaster recovery scenarios. The backhauling links for the base stations providing the 5G access in such scenarios would then be operated over either a terrestrial network (TN), or a non-terrestrial network (NTN), with a possibility to handover communications from a terrestrial network to a non-terrestrial network and vice-versa. Such base stations can be referred to as Wireless Access Backhaul (WAB) nodes, or mobile WAB nodes, or WAB nodes.

[0013] As part of these wireless backhauling enhancements, 3GPP is also considering some evolution to the former LTE-based Femto framework, including a new 5G Femto or 5G Femtocell that would offer 5G indoor coverage improvement while allowing high bandwidth and throughput at home for11031371W001 new immersive applications such as AR / VR / MR gaming, e-sports, UHD 8K video, telepresence, etc. It can be noted that a WAB node may deploy 5G Femto cells to serve UEs inside vehicles.

[0014] While moving, a WAB node may be handed over from the serving (source) base station to a target base station. When the WAB node is moving over long distances, the handover may involve to change the AMF (Access and Mobility management Function in the core network) and / or to change the UPF (User Plane Function in the core network) the WAB node connects to. In this case, the UEs served by the WAB node keeps the connection with the WAB node, but there is a possible change of the AMF and UPF. In particular, the NG (Next Generation) connection between the old AMF and the WAB node may not be used anymore, meaning this NG connection may be removed or suspended.

[0015] Besides, a WAB node that uses a Public Land Mobile Network (PLMN) to connect to the network through a wireless backhaul link, is subject to authorization. Also, the WAB node has to serve UEs through one or several PLMNs that may be different from the PLMN used by the WAB node for the backhaul link. Thus, the authorization for the WAB node is related to the authorization to use the backhaul link and the authorization to operate as a base station to serve the UEs. This authorization status is decided by an AMF (Access and Mobility management Function) in the core network, and the authorization status depends on the subscription associated to the WAB node, and on the geographical location of the WAB node. The authorization status for a WAB node may also be subject to changes (i.e. transition from authorized to non-authorized, or from non-authorized to authorized). In case the authorization status for a WAB node is changed from non-authorized to authorized, the NG connection(s) that may exist between AMF(s) and this WAB node shall be removed.

[0016] Considering a satellite embedding a full base station, this satellite base station connects to AMF(s) through a gateway on earth that may change while the satellite is moving around the earth. Thus, an AMF may not always be accessible for a satellite base station.

[0017] There is therefore a need to support removal and suspension of NG connection at a base station. Resumption of a suspended NG connection needs to be supported as well.

[0018] SUMMARY

[0019] In accordance with a first aspect of the invention, there is provided a method for use in managing connectivity of a radio access network, RAN, node, connectable to an access and mobility management function, AMF, entity of a core network via a Next Generation, NG, interface, the method at the AMF entity comprising:

[0020] receiving, from the RAN node, a request to suspend, resume or remove the NG interface; accepting or rejecting the request; and, in the case of accepting the request,11031371W001 suspending, resuming or removing the NG interface based on the request.

[0021] Optionally, the method further comprises the step of

[0022] sending a response to the RAN node indicating the AMF entity has accepted or rejected the request.

[0023] Optionally, in a case of accepting the request, the response includes one or more information element of a list comprising:

[0024] a message type information element;

[0025] an identification information element, wherein the value of the identification element identifies the AMF entity that has accepted the request;

[0026] a network retention information element;

[0027] a network release information element;

[0028] a user equipment, UE, release information element;

[0029] a UE retention information element; and

[0030] a criticality diagnostics information element.

[0031] Optionally, in a case of rejecting the request, the response includes one or more information element of a list comprising:

[0032] a message type information element;

[0033] a cause indication information element, wherein a value of the cause indication information element indicates a cause of rejection;

[0034] a criticality diagnostics information element; and

[0035] an alternative action information element.

[0036] Optionally, the request includes one or more information element of a list comprising: a message type information element;

[0037] an identification information element, wherein a value of the identification element identifies the RAN node sending the request;

[0038] a cause indication information element, wherein a value of the cause indication information element indicates a cause of (or reason for) the request;

[0039] a network retention information element;

[0040] a network release information element;

[0041] a user equipment, UE, release information element; and11031371W001 a UE retention information element.

[0042] Optionally, the RAN node is a wireless access and backhaul, WAB, node. Optionally, the WAB node is a mobile WAB node.

[0043] Optionally, the request is a request to suspend the NG interface, and the method further comprises suspending NG transmissions between the RAN node and the AMF over the NG interface. Optionally, the request may include an information element controlling the suspension of NG transmissions.

[0044] Optionally, the request is a request to resume the NG interface, and the method further comprises resuming NG transmissions between the RAN node and the AMF over the NG interface. Optionally, the request may include an information element controlling the resumption of NG transmissions.

[0045] In accordance with a second aspect of the invention there is provided a method for use in managing connectivity of a radio access network, RAN, node, connectable to an access and mobility management function, AMF, entity of a core network via a Next Generation, NG, interface, the method at the RAN node comprising:

[0046] receiving, from the AMF entity, a request to suspend, resume or remove the NG interface; accepting or rejecting the request; and, in the case of accepting the request,

[0047] suspending, resuming or removing the NG interface based on the request.

[0048] Optionally, the method further comprises the step of:

[0049] sending a response to the AMF entity indicating the RAN node has accepted or rejected the request.

[0050] Optionally, in a case of accepting the request, the response includes one or more information element of a list comprising:

[0051] a message type information element;

[0052] an identification information element, wherein the value of the identification element identifies the RAN node that has accepted the request;

[0053] a network retention information element;

[0054] a network release information element;11031371W001 a user equipment, UE, release information element;

[0055] a UE retention information element; and

[0056] a criticality diagnostics information element.

[0057] Optionally, in a case of rejecting the request, the response includes one or more information element of a list comprising:

[0058] a message type information element;

[0059] a cause indication information element, wherein a value of the cause indication information element indicates a cause of rejection;

[0060] a criticality diagnostics information element; and

[0061] an alternative action information element.

[0062] Optionally, the request includes one or more information element of a list comprising: a message type information element;

[0063] an identification information element, wherein a value of the identification element identifies the AMF entity sending the request;

[0064] a cause indication information element, wherein a value of the cause indication information element indicates a cause of (or reason for) the request;

[0065] a network retention information element;

[0066] a network release information element;

[0067] a user equipment, UE, release information element; and

[0068] a UE retention information element.

[0069] Optionally, the RAN node is a wireless access and backhaul, WAB, node. Optionally, the WAB node is a mobile WAB node.

[0070] Optionally, the request is a request to suspend the NG interface, and the method further comprises suspending NG transmissions between the RAN node and the AMF over the NG interface. Optionally, the request may include an information element controlling the suspension of NG transmissions.

[0071] Optionally, the request is a request to resume the NG interface, and the method further comprises resuming NG transmissions between the RAN node and the AMF over the NG interface.11031371W001 Optionally, the request may include an information element controlling the resumption of NG transmissions.

[0072] In accordance with a third aspect of the invention there is provided a method for use in managing connectivity of a radio access network, RAN, node, connectable to an access and mobility management function, AMF, entity of a core network via a Next Generation, NG, interface, the method at the AMF entity comprising:

[0073] following detection of a triggering condition,

[0074] sending, to the RAN node, a request to suspend, resume or remove the NG interface.

[0075] Optionally, the triggering condition is based on one or more of:

[0076] detection of the RAN node entering or leaving a predetermined geographic area; detection of a change in a core network to which the RAN node is connected; detection of a change to an authorization status of the RAN node;

[0077] detection of a change of a radio resource control, RRC, state of a mobile termination, MT, of the RAN node; and

[0078] expiration of a timer.

[0079] Optionally, the method further comprises the steps of;

[0080] receiving, from the RAN node, a response indicating whether the request is accepted or rejected; and, in the case of the request being accepted,

[0081] suspending, resuming or removing the NG interface based on the response.

[0082] Optionally, the request is a request to suspend the NG interface, and the method further comprises suspending NG transmissions between the RAN node and the AMF over the NG interface. Optionally, the request may include an information element controlling the suspension of NG transmissions.

[0083] Optionally, the request is a request to resume the NG interface, and the method further comprises resuming NG transmissions between the RAN node and the AMF over the NG interface. Optionally, the request may include an information element controlling the resumption of NG transmissions.11031371W001 In accordance with a fourth aspect of the invention there is provided a method for use in managing connectivity of a radio access network, RAN, node, connectable to an access and mobility management function, AMF, entity of a core network via a Next Generation, NG, interface, the method at the RAN node comprising:

[0084] following detection of a triggering condition,

[0085] sending, to the AMF entity, a request to suspend, resume or remove the NG interface.

[0086] Optionally, the triggering condition is based on one or more of:

[0087] detection of the RAN node entering or leaving a predetermined geographic area; detection of a change in a core network to which the RAN node is connected; detection of a change to an authorization status of the RAN node;

[0088] detection of a change of a radio resource control, RRC, state of a mobile termination, MT, of the RAN node; and

[0089] expiration of a timer.

[0090] Optionally, the method further comprises the steps of;

[0091] receiving, from the AMF entity, a response indicating whether the request is accepted or rejected; and, in the case of the request being accepted,

[0092] suspending, resuming or removing the NG interface based on the response.

[0093] Optionally, the request is a request to suspend the NG interface, and the method further comprises suspending NG transmissions between the RAN node and the AMF over the NG interface. Optionally, the request may include an information element controlling the suspension of NG transmissions.

[0094] Optionally, the request is a request to resume the NG interface, and the method further comprises resuming NG transmissions between the RAN node and the AMF over the NG interface. Optionally, the request may include an information element controlling the resumption of NG transmissions.

[0095] In accordance with a fifth aspect of the invention there is provided a method for use in managing connectivity of a radio access network, RAN, node, connectable to an access and mobility management function, AMF, entity of a core network via a Next Generation, NG, interface, the method at the AMF entity comprising:11031371W001 sending, to the RAN node, a first request to suspend, resume, reset or remove the NG interface;

[0096] receiving, from the RAN node, a second request to suspend, resume, reset or remove the NG interface;

[0097] comparing a priority of the first request to a priority of the second request; and suspending, resuming, resetting or removing the NG interface based on the comparison.

[0098] Optionally, the method comprises the step of

[0099] rejecting the request having the lower priority.

[0100] Optionally, in a case where the priority of the first request is equal to the priority of the second request, the method comprises the step of

[0101] aborting the first request.

[0102] Optionally, in a case where the priority of the first request is equal to the priority of the second request, the method comprises the step of

[0103] rejecting the second request.

[0104] Optionally, the priority of the first and / or second request is related to at least one of an order of priority associated with a type of entity from which the request is sent; and an order of priority associated with a type of procedure to which the request relates.

[0105] Optionally, in the order of priority associated with a type of entity from which the request is sent, an AMF entity has priority over a RAN node.

[0106] Optionally, in the order of priority associated with a type of procedure to which the request relates, an NG reset procedure has priority over an NG suspension procedure.

[0107] Optionally, in the order of priority associated with a type of procedure to which the request relates, an NG suspension procedure has priority over an NG removal procedure.

[0108] Optionally, the first and / or second request is a request to suspend the NG interface, and the method further comprises suspending NG transmissions between the RAN node and the AMF over11031371W001 the NG interface. Optionally, the first and / or second request may include an information element controlling the suspension of NG transmissions.

[0109] Optionally, the first and / or second request is a request to resume the NG interface, and the method further comprises resuming NG transmissions between the RAN node and the AMF over the NG interface. Optionally, the request may include an information element controlling the resumption of NG transmissions.

[0110] In accordance with a sixth aspect of the invention there is provided a method for use in managing connectivity of a radio access network, RAN, node, connectable to an access and mobility management function, AMF, entity of a core network via a Next Generation, NG, interface, the method at the RAN node comprising:

[0111] sending, to the AMF entity, a first request to suspend, resume, reset or remove the NG interface;

[0112] receiving, from the AMF entity, a second request to suspend, resume, reset or remove the NG interface;

[0113] comparing a priority of the first request to a priority of the second request; and suspending, resuming, resetting or removing the NG interface based on the comparison.

[0114] Optionally, the method comprises the step of:

[0115] rejecting the request having the lower priority.

[0116] Optionally, in a case where the priority of the first request is equal to the priority of the second request, the method comprises the step of:

[0117] aborting the first request.

[0118] Optionally, in a case where the priority of the first request is equal to the priority of the second request, the method comprises the step of:

[0119] rejecting the second request.

[0120] Optionally, the priority of the first and / or second request is related to at least one of:

[0121] an order of priority associated with a type of entity from which the request is sent; and an order of priority associated with a type of procedure to which the request relates.11031371W001 Optionally, in the order of priority associated with a type of entity from which the request is sent, an AMF entity has priority over a RAN node.

[0122] Optionally, in the order of priority associated with a type of procedure to which the request relates, an NG reset procedure has priority over an NG suspension procedure.

[0123] Optionally, in the order of priority associated with a type of procedure to which the request relates, an NG suspension procedure has priority over an NG removal procedure.

[0124] Optionally, the first and / or second request is a request to suspend the NG interface, and the method further comprises suspending NG transmissions between the RAN node and the AMF over the NG interface. Optionally, the first and / or second request may include an information element controlling the suspension of NG transmissions.

[0125] Optionally, the first and / or second request is a request to resume the NG interface, and the method further comprises resuming NG transmissions between the RAN node and the AMF over the NG interface. Optionally, the first and / or second request may include an information element controlling the resumption of NG transmissions.

[0126] In accordance with a seventh aspect of the invention there is provided a computer program comprising instructions which, when the program is executed by at least one processor unit, cause the at least one processing unit to carry out the method according to any one of the first to sixth aspects.

[0127] In accordance with an eighth aspect of the invention there is provided a computer-readable medium carrying a computer program according to the seventh aspect.

[0128] In accordance with a ninth aspect of the invention there is provided an apparatus for a backhaul Radio Access Network, RAN, node, the apparatus comprising:

[0129] one or more processing units configured to perform the method as recited in any one of the second, fourth and sixth aspects.

[0130] In accordance with a tenth aspect of the invention there is provided an apparatus for a Wireless Access Backhaul, WAB, node, the apparatus comprising:11031371W001 one or more processing units configured to perform the method as recited in any one of the second, fourth and sixth aspects.

[0131] In accordance with an eleventh aspect of the invention there is provided an apparatus for a Access and Mobility management Function, AMF, entity, the apparatus comprising:

[0132] one or more processing units configured to perform the method as recited in any one of the first, third and fifth aspects.

[0133] Optionally, when the request is a request to suspend the NG interface, the method may comprise suspending transmissions on the NG interface. When the request is a request to resume the NG interface, the method may comprise resuming transmissions on the NG interface. This optional feature may be used in combination with any of the aspects of the invention described herein. For example, transmissions on the NG interface between a WAB-gNB and a serving AMF may be suspended at the beginning of a handover procedure, and resumed on completion of the handover procedure. Similarly, transmissions on an NG interface between an NTN entity and a serving AMF may be suspended at the beginning of a gateway switch procedure, and resumed on completion of the gateway switch procedure. The suspension and / or resumption of NG transmissions may be automatic (for example as part of the NG interface suspend / resume procedure), may be triggered by a triggering event, or may be performed in response to a request from the entities using the NG interface (or another network entity). The suspension and / or resumption of NG transmissions may be performed as part of (in addition to) the NG interface suspend / resume procedure, or may be performed as a separate (standalone) procedure (i.e. without suspending the NG interface), on request of either entity or another network entity, or in response to a triggering event such as those described in connection with the NG interface suspend / resume procedure.

[0134] In the present disclosure, suspending an NG interface refers to suspending the NG connection between two network entities, and thus cancelling any NG traffic on this interface. When an NG interface is suspended, some configuration information and contextual information are stored in memory to enable quick resumption of the NG interface (i.e. the NG connection) at a later time when necessary. Suspending a NG interface / connection is appropriate when no NG traffic is needed or allowed for a relatively long period of time, for example for one or more hours.

[0135] Suspending NG transmissions means delaying (suspending) any NG traffic over the NG interface between two network entities without suspending the NG interface itself. Suspending NG transmissions (without suspending the NG interface / connection) is appropriate for a period of time11031371W001 typically shorter than the period of time for which an NG interface may be suspended. For example, NG transmissions over an NG interface may be suspended (delayed) for one or more seconds, or one or more minutes.

[0136] The invention in general relates to signalling to remove or suspend or resume a NG interface between a RAN node and an AMF.

[0137] This has particular relevance to a mobile communications network (e.g. 5G) utilizing WAB nodes. Other applications including other wireless communication networks such as WiFi where a mobile base station, or relay, or access point may be utilized.

[0138] In the example of a mobile communications network such as 5G, the messages are exchanged between the RAN node and the core network with a function in charge of managing a NG interface. Other network nodes like base stations may be involved to relay the protocol messages. Other wireless networks may have equivalent nodes and the invention may equally apply to these.

[0139] In the following description, the terms “NG interface” and “NG connection” can be used with the same meaning.

[0140] Further example features of the invention are described in other independent and dependent claims.

[0141] Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to apparatus / device / unit aspects, and vice versa.

[0142] Furthermore, features implemented in hardware may be implemented in software, and vice versa. Any reference to software and hardware features herein should be construed accordingly. For example, in accordance with other aspects of the invention, there are provided a computer program comprising instructions which, when the program is executed by one or more processing units, cause the one or more processing units to carry out the method of any aspect or example described above and a computer readable storage medium carrying the computer program.

[0143] BRIEF DESCRIPTION OF THE DRAWINGS

[0144] Different aspects and embodiments of the invention will now be described, by way of example only, and with reference to the following drawings in which:

[0145] Figure 1 is a schematic diagram of a communication system in which the present invention may be implemented according to one or more example embodiments;

[0146] Figure 2 is a simplified schematic diagram of a 5G system in which the present invention may be implemented according to one or more example embodiments;11031371W001 Figure 3 is a simplified schematic diagram of a 5G system involving a Wireless Access Backhaul (WAB) node, and in which the present invention may be implemented according to one or more example embodiments.

[0147] Figure 4 is a block schematic diagram of an example network node or base station in accordance with one or more embodiments of the invention;

[0148] Figure 5 is a simplified schematic diagram showing an example of a wireless communication system, including a WAB network or WAB network system, in which embodiments and examples of embodiments of the present invention may be implemented;

[0149] Figure 6a is a schematic diagram illustrating the protocol stack associated to the NG interface in the user plane (NG-U);

[0150] Figure 6b is a schematic diagram illustrating the protocol stack associated to the NG interface in the control plane (NG-C);

[0151] Figure 7a is a schematic diagram showing an example message flow for performing the procedure for NG interface removal between a NG-RAN node and an AMF, where the removal is initiated by the NG-RAN node;

[0152] Figure 7b is a schematic diagram showing an example message flow for performing the procedure for NG interface removal between a NG-RAN node and an AMF, where the removal is initiated by the AMF;

[0153] Figure 8a is a schematic diagram showing an example message flow for performing the procedure for NG interface suspension between a NG-RAN node and an AMF, where the suspension is initiated by the NG-RAN node;

[0154] Figure 8b is a schematic diagram showing an example message flow for performing the procedure for NG interface suspension between a NG-RAN node and an AMF, where the suspension is initiated by the AMF;

[0155] Figure 9a is a schematic diagram showing an example message flow for performing the procedure for NG interface resumption between a NG-RAN node and an AMF, where the resumption is initiated by the NG-RAN node;

[0156] Figure 9b is a schematic diagram showing an example message flow for performing the procedure for NG interface resumption between a NG-RAN node and an AMF, where the resumption is initiated by the AMF;

[0157] Figure 10 is a flowchart of an example method for initiating and managing at a NG-RAN node or an AMF, the removal or suspension or resumption of a NG interface;

[0158] Figure 11 is a flowchart of an example method for managing at a NG-RAN node or an AMF, a request for the removal or suspension or resumption of a NG interface;11031371W001 Figure 12 is a flowchart of an example method for managing at a NG-RAN node or an AMF, abnormal conditions at the removal or suspension or resumption of a NG interface;

[0159] DETAILED DESCRIPTION

[0160] Figure 1 illustrates an example communication system 100 in which the present invention may be implemented according to one or more embodiments.

[0161] As depicted, the example system 100 is a wireless communication system, in particular a mobile radio communication system such as a fifth-generation (5G) New Radio (NR) system including a Wireless Access Backhaul (WAB) communication system or network. Although in the following description, embodiments and examples of embodiments of the present invention will be described with respect to a 5G NR system, it will be appreciated that it is not intended that the present invention is limited to 5G NR systems and may be used in any wireless communication systems having an integrated access and backhaul communication system which shares radio resources for wireless access links and wireless backhaul links.

[0162] The system 100 comprises a plurality ofUEs (User Equipment) 111, 112, 113, 121, 122, 123, 131, 132, 133, 134, 141, 142, 143, 151, 152, 153 and 154, a communication satellite 160, a satellite dish 101, a remote core network 170, three fixed Base Stations 102, 103 and 104, a plurality of Wireless Access Backhaul (WAB) nodes 110 (mounted on plane 161), 120a and 120b (mounted on train 162), 140 (mounted on Unmanned Aerial Vehicle (UAV) UAV 164) and 150 (mounted on backpack 165 or other carrier that can be carried by a user (e.g. in a disaster zone)), and a Wireless Access Backhaul node 130 (or Home gNB, mounted in house 163) which is fixed but based on the same architecture as a WAB node. In more general terms, the WAB node may be mounted on or in a vehicle (such as a train, bus, taxi, tram, etc.) and / or an aircraft or flying vehicle (such as a plane, UAV, helicopter, etc. ) and / or a building (such as a house, enterprise / company / office building, hotel building, airport building, sports / event buildings, shopping centre building, etc..) and / or a portable carrier that can be carried by a user (such as a backpack, bag, etc), for example, in a disaster zone or for public safety or for emergency services, and / or public infrastructure elements or units (such as lamp posts, traffic lights, etc.). In an example where the WAB node is implemented in a Femto network, the WAB node functions as a 5G Femto node and may be mounted at a building (such as a house, enterprise / company / office building, hotel building, airport building, sports / event buildings, shopping centre building, etc..) and / or public infrastructure elements or units (such as lamp posts, traffic lights, etc.). When it is a mobile base station, a WAB node is also referred to as a Mobile WAB (MWAB) node.

[0163] Some examples of UEs include smartphones / tablets (such as UEs 111, 123, 134, 142, 152), XR headsets (such as UEs 112, 122, 132), cameras (such as UEs 141 and 151), fixed video cameras11031371W001 (such as UEs 113, 121, 133, 153) or mobile / wearable video cameras (such as UEs 143 and 154). In general, the UE may be any portable or handheld or mobile telephone, a smartphone, a tablet, a portable or fixed computer, fixed or mobile camera, portable television or other similar wireless communication device. In the following description, the term UE will be used and it is not intended to limit the description to any particular type of wireless communication device.

[0164] Base stations 102, 103 and 104 are interconnected through a wired link infrastructure 180, preferably based on optical fiber or any other wired means.

[0165] Base stations 102, 103 and 104 are also connected to the core network 170 through a wired link infrastructure 190, preferably based on optical fiber or any other wired means. In embodiments and examples of embodiments of the invention, base stations 102, 103 and 104 are 5G NR base stations (referred to as a gNB), as defined in 3GPP TS 38.300 vl8.0.0 specification document.

[0166] Satellite dish 101 (e.g. satellite gateway) is also connected to wired link infrastructure 180 or 190, or to both infrastructures. Besides infrastructures 180 and 190 may be the same infrastructure. In one example, a part of a base station is embedded in the satellite 160 while the other part is embedded in the gateway 101 , meaning that the base station is split between the satellite 160 and the gateway 101. In another example, a full base station is embedded in the satellite 160 and the gateway 101 connects the base station 160 with the infrastructure 180 or 190. In case of non-geostationary satellite, the satellite 160 may connect to different gateways, like the gateway 101, while the satellite 160 is moving around the earth.

[0167] In order to extend the network coverage of base stations 102, 103 and 104 and reach the remote UEs 111, 112, 113, 121, 122, 123, 131, 132, 133, 134, 141, 142, 143, 151, 152, 153 and 154, mobile WAB nodes or WAB nodes, or WAB-nodes, 110, 120a, 120b, 130, 140 and 150, have been installed on vehicles / mobile equipment 161, 162, 163, 164 and 165. By acting as relaying nodes between the base stations 102, 103 and 104 and the UEs 111, 112, 113, 121, 122, 123, 131, 132, 133, 134, 141, 142, 143, 151, 152, 153 and 154, WAB-nodes 110, 120a, 120b, 130, 140 and 150 allow overcoming the reachability issue resulting from limited sky visibility while ensuring support for onboard / on-site mobile edge computing (MEC), local services, and direct local inter-UE communications. This allows further communication between base stations 102, 103 and 104 and the UEs 111, 112, 113, 121, 122, 123, 131, 132, 133, 134, 141, 142, 143, 151, 152, 153 and 154 and / or communications between the UEs served by a same WAB-node (e.g., UEs 151, 152, 153 and 154 connected to WAB node 150).

[0168] The base stations 102, 103 and 104, the WAB nodes 110, 120a, 120b, 130, 140 and 150, the satellite 160, the satellite dish 101 are thus forming a backhaul network or WAB network (also referred to as WAB topology), or WAB network (also referred to as WAB topology), which11031371W001 accommodates UEs 111, 112, 113, 121, 122, 123, 131, 132, 133, 134, 141, 142, 143, 151, 152, 153 and 154.

[0169] The terms WAB network, WAB network, WAB topology and WAB topology will be used interchangeably in the following. The WAB network is part of the Radio Access Network (RAN) or as referred to with respect to 5G, the Next Generation (NG) RAN.

[0170] The base stations 102, 103 and 104, the WAB nodes 110, 120a, 120b, 130, 140 and 150, the satellite 160, the satellite dish 101, and the core network 170 are thus forming a WAB system, or WAB system, which accommodates UEs 111, 112, 113, 121, 122, 123, 131, 132, 133, 134, 141, 142, 143, 151, 152, 153 and 154.

[0171] The terms WAB system and WAB system will be used interchangeably in the following. A base station, or gNB, such as base station 102, 103 or 104, is a logical node that provides the NR-connectivity, hosting both higher layer protocols, such as PDCP (Packet Data Convergence Protocol) and RRC (Radio Resource Control) protocols, and lower layer protocols, such as the RLC (Radio Link Control), MAC (Medium Access Control) and physical layer protocols.

[0172] The WAB nodes 110, 120a, 120b, 130, 140 and 150, which may serve multiple radio sectors, are wireless backhauled to the base station 102, 103 or 104, via a single logical hop associated to a single radio link (i.e., radio links D1041a, D1041b, D1031, D1022, D1021), or split into two radio links in the case of satellite relaying (radio links DI 60 la and DI 60 lb). Although a single logical hop is shown in figure 1, it will be appreciated that the WAB nodes could be wirelessly backhauled to the base station over multiple logical hops (for example, similar to the multiple hops provided in an I AB network).

[0173] Each WAB node consists or includes a gNB or RAN node or base station component or entity which is referred to as a WAB-gNB, or WAB base station, and Mobile Termination (MT) component or entity which is referred to as an IAB-MT, or WAB-Mobile Termination. The WAB-gNB functionality on an WAB-node allows or enables the WAB-node to serve UEs. The WAB-MT functionality includes, e.g., physical layer, layer-2, RRC and Non-Access Stratum (NAS) functionalities and allows or enables the WAB-MT to connect to a fixed base station, or gNB, such as base station 102, 103 or 104.

[0174] WAB nodes 110, 120a, 120b, 140 and 150 are intended to be mobile devices that will move along with the vehicle they are mounted on. However, these WAB nodes may remain at a fixed location for a significant duration when their associated vehicle is remaining still (e.g., a train may stop at a railway station, a plane may be parked at an airport for a while, a car / truck / fire engine or any other emergency vehicle may be parked nearby a disaster area).11031371W001 WAB node 130 is likely to remain at fixed location and may be a 5G Femto node, which provides NR access at home or at enterprise premises. In such case, the 5G Femto node 130 may have a direct connection DI 700 to the Core Network 170 through the wired link infrastructure 190, which is preferably based on optical fiber or any other wired means.

[0175] Figure 2 is a simplified schematic diagram of a 5G system 200 in which the present invention may be implemented according to one or more example embodiments. This figure illustrates the possible standardized interfaces between the various elements composing the system. First, it represents a User Equipment (UE) 201 having a Uu interface with the New Generation (NG) Radio Access Network (RAN or NG-RAN) 202, and a N1 interface with an Access and Mobility management Function (AMF) entity or AMF 212 in a 5G core network (5GC) 210. Each base station composing the RAN 202 has a N2 interface with one or more Access and Mobility management Function (AMF) entity or AMF, like AMF 212, and a N3 interface with one or more User Plane Function (UPF) entity or UPF, like UPF 211.

[0176] The N1 interface is used to convey Non-Access Stratum (NAS) protocol messages between a UE 201 and an AMF 212. NAS messages are used for the signaling between the UE and the core network for various procedures such as registration, session establishment, security, and mobility management. Actually, NAS messages are conveyed through the Uu interface between the UE 201 and the RAN 202, and the N2 interface between the RAN 202 and the AMF 212.

[0177] An AMF 212 is responsible for handling registration, authentication, connection and mobility management tasks for a UE. For a WAB node, the AMF may apply the procedures defined in NAS protocol specifications (TS 24.502 section 5), considering the WAB node is a Mobile Base Station Relay (MBSR) introduced in Release 18. There may be several AMFs in a 5G core network, a standardized interface N14 enables the communications between AMFs. When a UE registers to the network through a serving base station, the serving base station will connect to an AMF suitable to handle the UE.

[0178] When the UE 201 is registered, one or more Protocol Data Unit (PDU) session(s) can be set up to transfer data flows between the UE 201 and the Data Network (DN) 220 providing internet access. A PDU session is established between a UE 201 and a User Plane Function (UPF) 211 in the 5G core network 210. In the user plane, the UPF 211 connects to the Data Network (DN) 220 through the interface N6, and it is responsible for data packets routing with the required Quality of Service (QoS). There may be several UPFs on the data path with a N9 interface between UPFs. The user data between a UE 201 and the Data Network 220 are thus conveyed through interfaces Uu, N3, N6 and potentially N9.11031371W001 In the control plane, the setup of PDU sessions is handled through NAS messages involving the Session Management Function (SMF) entity or SMF 213 in the 5G core network 210. The NAS messages are still exchanged between the UE 201 and the AMF 212 through the N1 interface, but an additional interface N11 between an AMF 212 and the SMF 213 is used to reach the SMF 213. In a 5G core network, the SMF is responsible for the setup, modification, and release of PDU sessions for a UE, as well as the Internet Protocol (IP) address allocation for the UE. To manage a PDU session, the SMF 213 controls the UPF 211 (configuration) based on QoS policy defined for the PDU session. For this purpose, a N4 interface exists between the SMF 213 and the UPF 211.

[0179] A base station in RAN 202 operating in a first Public Land Mobile Network (PLMN) may serve a UE having a subscription for a second PLMN (called home PLMN) different from the first PLMN (called visited PLMN). In such a roaming case, there are two options to provide the UE 201 with an access to the Data Network 220. In a first option called home routed, the UPF and its controlling SMF to access the Data Network 220 are located in the 5G core network for the home PLMN. However, the SMF of the visited PLMN controls the intermediate UPF(s) of the visited PLMN, and interacts with the SMF of the home PLMN. In a second option called local breakout, the UPF and its controlling SMF to access the Data Network 220 are located in the 5G core network for the visited PLMN. However, the SMF interacts with the home 5G core network to get QoS policies associated with the UE’s PDU session(s).

[0180] Figure 3 is a simplified schematic diagram of a 5G system 300 involving a Wireless Access Backhaul (WAB) node (or a MW AB node), and in which the present invention may be implemented according to one or more example embodiments. This figure first represents a User Equipment (UE) 301 served by a WAB node 310 through the Uu interface. The WAB node 310 is composed of or includes a MT or WAB-MT or MWAB-MT unit / component / entity 311 (also called WAB-UE), and a gNB or WAB-gNB, or MWAB-gNB unit / component / entity 312. Through the WAB-gNB 312, a WAB node acts as a gNB for UEs providing access to the 5G network, i.e. providing a NR access link to the UEs that can be located inside or outside the entity, such as a vehicle, equipped with the WAB node 310 (e.g. on entering / leaving the vehicle). In other words, the WAB-gNB 312 includes full base station or gNB function (including both Central Unit (CU) and distributed unit (DU)) and MT function, where the gNB function is used to communicate with UEs for access service and the MT function is used to communicate with another gNB for backhauling purpose. The WAB node 310 wirelessly connects to the 5G Core Network (using NR Uu interface) through an IP connectivity provided by PDU session(s) established by the WAB-MT 311 via a gNB 320, which can be called a backhaul RAN node, BH RAN node, backhaul base station, backhaul gNB or BH gNB. Acting as a legacy UE, the WAB-MT 311 connects via a NG-RAN cell of the BH gNB 320, through a11031371W001 backhaul link that may be a direct link or via a satellite (e.g. when the WAB node 310 is embedded in an airplane). Thus, a PDU session is provided either by a Terrestrial Network (TN) or by a NonTerrestrial Network (NTN). In addition, the WAB node 310 may embed some core network functions, like a UPF 313, to enable local services to the served UEs. The traffic associated to these local services does not need to use the links to / from the core network via the BH gNB 320, which has the advantages to reduce the load on these links and to run applications having very low latency requirements. For example, where the WAB node 310 includes a UPF 313, the WAB node can connect to one or more local servers (e.g. mounted at the same entity as the WAB 310) enabling a UE served by the WAB access to local services provided by the local servers with no traffic required outside of the WAB node / server environment.

[0181] The BH gNB 320 provides N3 and N2 interfaces so that the WAB-MT 311 can access to the functions of its 5G core network 330. Indeed, a WAB-MT 311 may have access to some or several PLMNs through the appropriate subscriptions, and it may connect in a non-roaming manner to one PLMN, e.g. PLMN1 supported by the BH gNB 320, and may then have access to the corresponding 5G core network 330. In particular the WAB-MT 311 interacts with the AMF 332, which can be called the WAB AMF, and establishes PDU session(s) with the UPF 331, which can be called the WAB UPF. The WAB UPF 331 is controlled by the SMF 333 (through N4 interface), which can be called the WAB SMF, and which also interacts with the WAB AMF 332 (through Nil interface). There may be one or several intermediate UPFs between the BH gNB 320 and the WAB UPF 331 as mentioned in the Figure 2.

[0182] An interface internal to the WAB node 310 exists between the WAB-gNB 312 and the WAB-MT 311, which may be implemented on different or the same hardware resources. For instance, these two functions are implemented on the same processing unit 402 of Figure 4, and interactions exist between the two functions.

[0183] Once the WAB-MT 311 has established a PDU session with the WAB UPF 331, the WAB node is ready to serve UEs and the WAB-gNB 312 can start operating as a legacy gNB. The WAB-gNB may support various PLMNs and the UE 301 connects to one PLMN, e.g. PLMN2, which may be different from the PLMN 1 the WAB-MT 311 connects to. In the case where PLMN 1 and PLMN2 are different, the UE 301 connects to the 5G core network 340, including a UPF 341, which can be called the UE UPF, an AMF 342, which can be called the UE AMF, and a SMF 343, which can be called the UE SMF. The UE SMF 343 interacts with the UE AMF 342 (through N11 interface) and the UE UPF 341 (through N4 interface). In the case where the PLMN1 and the PLMN2 are the same, the UE UPF 341, the UE AMF 342, the UE SMF 343, the WAB UPF 331, the WAB AMF 332, and the WAB SMF 333 belong to the same 5G core network 350. In addition, the UE UPF 34111031371W001 and the WAB UPF 331 may be the same UPF, the UE AMF 342 and the WAB AMF 332 may be the same AMF, the UE SMF 343 and the WAB SMF 333 may be the same SMF.

[0184] The connections between the UE 301 to the UE UPF 341 and to the UE AMF 342 are possible thanks to the N6 interface between the UE UPF 341 and the WAB UPF 331, and thanks to the N6 interface between the WAB UPF 331 and the UE AMF 342. These N6 interfaces enable the establishment of N2 interface between the WAB-gNB 312 and the UE AMF 342, and the establishment of N3 interface between the WAB-gNB 312 and the UE UPF 341, which allows the UE 301 to access the Data Network 360.

[0185] In case the WAB-MT 311 connects to the 5G network in a roaming manner corresponding to the home routed option, then the PLMN1 is the visited PLMN and the WAB UPF 331 connects to another UPF not represented in the Figure 3 in the home PLMN through a N9 interface. It is this other UPF that provides the connection to the UE UPF 341 and the UE AMF 342 through N6 interfaces.

[0186] In case the WAB-MT 311 connects to the 5G network in a roaming manner corresponding to the local breakout option, then the PLMN1 is the visited PLMN and the WAB UPF 331 directly connects to the UE UPF 341 and the UE AMF 342 through N6 interfaces as shown in the Figure 3.

[0187] Figure 4 is a block schematic diagram of an example network node or RAN node or base station 400, such as base stations or gNBs or WAB nodes shown in Figure 1, in accordance with one or more embodiments of the invention. Each of a WAB node 110, 120a, 120b, 130, 140, or 150 of figure 1 may comprise the elements of the base station of figure 4. Also, the satellite 160 of figure 1 may comprise the elements of the base station of figure 4. In the following description, the network node 400 will be referred to generally as a base station. As will be apparent to a skilled person, Figure 4 is a simplified schematic diagram and shows only some of the functional components of an example base station 400 for use in describing the one or more embodiments of the invention.

[0188] The base station 400 includes components for transmitting and receiving communications. As shown in Figure 4, the base station 400 includes a processing unit 402, a wireless interface 404, one or more antennas 410, a network interface 432, and memory 418.

[0189] The network interface 432 manages communications of the base station 400 with the core network, other base stations, local network functions (like UPF), or local servers. It may provide a standardized interface, wired (e.g. fiber) or wireless, to support these communications. Through this network interface 432, the base station 400 may implement the standardized interfaces N2 (based on NGAP protocol) and N3 (based on GPRS tunneling protocol) with the core network, and the standardized interface Xn (based on XnAP protocol) with other base station of the Radio Access Network (RAN), all defined by the 3 GPP standard. The network interface 432 may not be present11031371W001 or active in case the base station 400 is a WAB node that does not support local services, that is not used as a legacy base station like base station 102, 104 in Figure 1, and that is not used as a home base station providing Femto cells like base station 130 in Figure 1.

[0190] The wireless interface 404 is configured to provide wireless communication via communication links (414) with other wireless devices, such as one or more UEs, e.g. link DI 04 lb between base station 104 and the MT / UE unit of WAB node 120b, or link D1202 between the gNB unit of WAB node 120b and the UE 122. In case of WAB node, the wireless interface 410 may then be used both for the wireless backhaul link(s) with backhaul base station(s) and for the wireless link(s) with the UE(s) served by the WAB node. The wireless interface 404 may be compliant with a fifth-generation (5G) New Radio (NR) system and thus implementing the Uu interface defined by 3GPP standard, or with other wireless communication system. The wireless interface 404 is coupled to the processing unit 402 and typically includes one or more antennas (such as the antenna 410), a receiving unit 406 and a transmitting unit 408. The configuration of the wireless interface 404 may be limited to connect to one antenna, but preferably several antennas are used, in order to provide beamforming capability. Although not shown in Figure 4, the receiving unit 406 typically includes elements such as a receiver, demodulator, decoder, and the transmitting unit 408 typically includes elements such as a transmitter, modulator, coder. The receiving unit 406 and transmitting unit 408 may together be referred to as a transceiver.

[0191] The processing unit 402 is configured to carrying out processing for operation of the base station 400. The processing unit 402 may be a single processor (e.g. Central Processing Unit) or may comprise two or more processors. The number of processors and the allocation of processing functions to the processors is a matter of design choice for a skilled person. The base station 400 includes memory 418 for storing data and computer programs containing instructions for the operation of the base station 400. Memory 418 includes RAM (Random Access Memory), ROM (Read Only Memory), or combination of both or as a non-limiting example a mass storage device such as a disk or a Solid-State Drive. Memory 418 includes a program memory in which are stored programs containing processor instructions for operation of the base station 400 and for implementing the methods in accordance with one or more embodiments of the invention. The programs may contain a number of different program elements or sub-routines containing processor instructions for a variety of different tasks, for example, for: establishing, controlling and releasing communications with the UEs (e.g. implementing the Uu interface); processing data and signalling received at the receiving unit 406; processing signalling (e.g., paging messages, System Information Blocks) and data for transmission by the transmitting unit 408. Memory 418 may further include memory (e.g. RAM) for storing information. For example, information stored in memory 418 may11031371W001 include information associated with the WAB node, such as information elements 420 related to a NG interface. The operation of the information elements 420 will be described in more detail below.

[0192] In an example arrangement, a communication bus 424 provides communication and interoperability between the various elements included in the base station 400 or connected to it. The representation of the bus is not limiting and in particular, the processing unit 402 is operable to communicate instructions to any element of the base station 400 directly or by means of another element of the base station 400.

[0193] In an example implementation, the base station 400 may be or may include an apparatus comprising one or more processing units or processors for performing or implementing the methods in accordance with one or more embodiments of the invention. In other words, the apparatus is capable of performing one or more functions of the base station including performing the methods in accordance with one or more embodiments of the invention by means of the one or more processing units. For example, the one or more processing units uses software to implement the one or more embodiments of the invention as described above with reference to the processing unit 402 of Figure 4. Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, a CPU of a microcontroller Unit (MCU), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other equivalent integrated (e.g. on an Integrated Circuit) or discrete logic circuitry. However, alternatively, the one or more processing units for performing or implementing the methods may be implemented in hardware: for example, in the form of an Application Specific Integrated Circuit or ASIC or other hardware comprising logic element (s). Accordingly, the term “processing unit” as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein.

[0194] In a 5G core network, an AMF (Access and Mobility management Function) like the WAB AMF 332 or the UE AMF 342, may be implemented with the apparatus described in the Figure 4 where the Wireless Interface 404 and the antenna 410 is not present.

[0195] Figure 5 illustrates an example of a wireless communication system 500, including a WAB network or WAB network system, in which embodiments and examples of embodiments of the present invention may be implemented.

[0196] A WAB network will also be referred to as a WAB network system, WAB topology, WAB system, topology or system and so in this application, the terms WAB network system, WAB network, WAB topology, WAB system, topology or system will be used interchangeably.

[0197] The WAB network system of Figure 5, is composed of three base stations 501, 502 and 503, also referred to as Backhaul base stations, or backhaul RAN nodes (also referred to as BH RAN11031371W001 nodes), or backhaul gNBs (also referred to as BH-gNB), two core networks 510 and 520, with the respective AMF entities 511a and 511b (for Core Network 510) and 521a and 521b (for Core Network 520) and the respective UPF entities 512a and 512b (for Core Network 510) and 522a and 522b (for Core Network 520), and two WAB nodes 530 and 540.

[0198] A wired backhaul IP network 590 interconnects the base stations 501, 502 and 503 and the Core Networks 510 and 520. For instance, this wired link consists of optical fiber cable(s).

[0199] As discussed above, each WAB node comprises a Mobile Termination (MT) part or unit (WAB-MT 531 for WAB node 530 and WAB-MT 541 for WAB node 540) and a RAN node or base station part or unit (WAB-gNB 532 for WAB node 530 and WAB-MT 542 for WAB node 540).

[0200] WAB node 530 and WAB node 540 may also embed a UPF entity, respectively UPF entity 533 and UPF 543, as previously discussed in figure 3, allowing WAB-node 530 to provide UEs 551, 552 and 561 with some local services, such as for instance inter-UE communication where the user data exchanged between the two UEs would be routed through UPF entity 533 instead of being routed through a UPF entity belonging to Core Network 510 or 520.

[0201] WAB node 530 is connected to the serving backhaul base station referred to as BH-gNBl, 501 through BH link 5011.

[0202] WAB node 540 may be connected to the serving backhaul base station referred to as BH-gNB2, 502 through BH link 5021 or to the serving backhaul base station referred to as BH-gNB3, 503 through BH link 5031 or, in case of dual connectivity, to both the serving backhaul base station BH-gNB2, 502 through BH link 5021 and the serving backhaul base station BH-gNB3, 503 through BH link 5031.

[0203] WAB-gNB 532 of WAB node 530 is also connected to UE 551 through communication link or radio link 5301 and to UE 552 through communication link or radio link 5302.

[0204] Similarly, WAB-gNB 542 of WAB node 540 is also connected to UE 561 through communication link or radio link 5401.

[0205] Although Figure 5 shows only UE 561 connected to WAB node 540, it will be appreciated that there will be a plurality of UEs connected to WAB nodes of the wireless communication system.

[0206] WAB-gNB 532 and WAB-MT 531 may be connected to a same AMF function or entity (e.g., AMF 511a) or to different AMF functions or entities belonging to the same Core Network (e.g., AMF 511a and AMF 51 lb) or to different Core Network (e.g., AMF 511a and AMF 521a).

[0207] Some AMF functions may be implementing WAB-specific features for managing a WAB node (e.g., advanced mobility features). Some AMF functions may not implement such features but11031371W001 may still be capable of serving a WAB node with a limited set of basic features. Some AMF functions may not be capable of serving a WAB node.

[0208] The processes and arrangements for managing one or more network connections and managing WAB node authorization in a wireless communication system including one or more WAB nodes will now be described according to some embodiments of the present invention.

[0209] Several scenarios are possible according for the mobility of WAB nodes 530 and 540.

[0210] As a first scenario, and taking the example of WAB node 540, a dual-connectivity configuration may be applied to the WAB-MT 541, initially connected to BH-gNB2 502 only through the link 5021. Indeed, the WAB-MT 541 periodically performs a cell search procedure, as defined in 3GPP TS 38.300, trying to detect PSS (Primary Synchronization Signal) and SSS (Secondary Synchronization Signal). The WAB-node may report to BH-gNB2 502 the presence of a new cell, for instance one cell managed by the BH-gNB3 503, through a measurement report. Based on the analysis of the measurement report, the BH-gNB2 502 may request to the BH-gNB3 503 the establishment of a dual connectivity for the WAB-MT 541 with an additional connection through the link 5031. The BH-gNB3 503 may accept the request and proceed to the connection of the WAB-MT 541 according to the procedure described in TS 37.340 section 10.2.2. As a result, the WAB-MT 541, and thus the WAB node 540 is dual-connected. The BH-gNB2 502 may take benefit of the dual connectivity of WAB node 540 to balance the traffic load by offloading some traffic (data / user traffic or control traffic) initially planned to be transmitted through the link 5021. Some or all the traffic associated to the WAB node 540 (i.e. control data related to the WAB node, and control and user data related to the UEs served by the WAB node 540) may be transmitted through the link 5031 and through the IP connectivity between BH-gNB2 502 and BH-gNB3 503. Dual -connectivity configuration is however transparent for the MWAB-gNB 542 and for the UEs served by the WAB-gNB 542.

[0211] As a second scenario, the radio link 5021 may experience radio link deficiency due to some unexpected interference or shadowing phenomena. For such reasons, the WAB-MT 541 may lose the connection with the BH-gNB2 502 and declare a Radio Link Failure (RLF). Then, the WAB-MT 541 will try to reestablish the connection in the same or a different cell controlled by BH gNB2 502 or by another gNB. Thus, the WAB-MT 541 may try to connect to a cell controlled by BH-gNB3 503 by requesting the establishment of the link 5031. In this case, the reestablishment procedure described in TS 38.300 section 9.2.3.3 may be applied, which enables a UE to maintain the RRC connection. With such procedure, the BH gNB3 503 sends to the BH gNB2 502 a request to retrieve the context of the WAB-MT 541. Based on the response from the BH gNB2 502, the BH gNB3 503 may accept the connection of the WAB-MT 541. Then, all the traffic related to the WAB11031371W001 node 540 (and the served UEs) will now transit through the BH gNB 503. The reestablishment procedure does not involve the WAB-gNB 542 and its served UEs. If the reestablishment is rapidly performed after RLF, the service interruption at the UE 561 may be avoided or limited.

[0212] As a third scenario, the WAB-MT 541 may be handed over from the current serving cell to a new cell. Indeed, based on the measurement reports provided by the WAB-MT 541, the BH-gNB2 502 may detect that the WAB-MT 541 would have a better connection through a cell managed by the BH gNB3 503. Then, the BH-gNB2 502 may trigger a handover procedure described in TS 38.300 section 9.2.3.2. In this procedure, the BH-gNB2 502 sends a handover request to the BH gNB3 503 along with information related to the WAB-MT 541. Based on this information, the BH gNB3 503 may accept the handover request and proceed to the admission of the WAB-MT 541. Then, all the traffic related to the WAB node 540 (and the served UEs) will now transit through the BH gNB 503. The handover procedure does not involve the WAB-gNB 542 and its served UEs, and it may be transparent for WAB-gNB and the served UEs (no interruption of service).

[0213] The second and third scenario corresponds to the mobility of the WAB node 540 that may involve a new backhaul gNB serving the WAB-MT 541 in RRC_CONNECTED state. This may mean that the WAB node 540 is located in a new geographical area and the authorization status of the WAB node should be re-evaluated. For example, in the new geographical area the WAB node 540 may not be authorized to operate as a WAB node or in the new geographical area the WAB node 540 may be authorized but the authorization has changed. For example, in a previous geographical area the WAB node was authorized to provide local services whereas in the new geographical area the WAB node is not or no longer authorized to provide local services. In this case the existing NG interface with AMF(s) shall be removed. Regardless the authorization status, a WAB node entering in a new geographical area may have to connect to different AMF and / or UPF to continue serving UES. Indeed, the AMF(s) with which the WAB-gNB is currently connected, may no longer be involved for serving UEs. Thus, the removal of NG interface(s) with this AMF(s) may be performed to save some resources both a WAB-gNB and the AMF(s).

[0214] Besides, in case of known trajectory for the WAB node, where it is expected that the WAB node comes back to the same geographical area, the existing NG interface with AMF(s) may be suspended, then to be resumed later.

[0215] With the example of figure 5, the WAB-MT 541 was served by BH-GNB2 502 and the WAB-gNB 542 was connected to AMF(s) 511a, 511b in the core network 510. After handover or reconnection of WAB-MT 541 toward the BH-gNB3 503, the WAB-gNB 542 may remove or suspend the NG interface(s) with AMF(s) 511a, 511b, and may connect to AMF(s) 521a, 521b in the core network 520.11031371W001 In other words, the NG connection(s) of a WAB-gNB whose authorization status changes from “authorized” to “not authorized” can be removed. It needs to be further studied whether NG connection(s) can be suspended.

[0216] When considering a WAB node having a “loop” trajectory, i.e., where it is expected that the WAB node moves along a predefined path, while coming back to its starting point on a periodic basis, the existing NG connection(s) with AMF(s) may be suspended, and resumed later. For some WAB nodes, there may be no strong constraints on hardware resources (as it is the case for satellites), and there would be no issue to keep in memory some parameters related to suspended NG connections.

[0217] To prevent from maintaining some suspended NG connections forever, e.g., if the trajectory of a WAB node is finally not as planned, some timer may be used to trigger the removal of suspended NG connections.

[0218] Still considering a WAB node, there may be radio data loss and temporary service interruption at the UEs served by the WAB node when the WAB-MT of the WAB node is handed over from a source backhaul gNB to a target backhaul gNB, even when there is no need to switch to a new AMF. To prevent such a loss of user data (i.e. NG user data or NG-U data) and / or of control data (i.e. NG application protocol data or NG-C data) during handover of a WAB-MT, the NG transmissions (NG-U and NG-C) between the WAB-gNB (co-located with the WAB-MT in the WAB node) and the serving AMF(s) may be suspended at the beginning of the handover procedure, and resumed at the completion of the handover procedure.

[0219] Furthermore, considering a satellite hosting a gNB (i.e. a NTN satellite gNB or NTN gNB), there may be radio data loss and temporary service interruption at the UEs served by the NTN gNB when the NTN gNB switches from a first Earth station (or first NTN gateway) to a second Earth station (or second NTN gateway), with or without changing of served AMF. To prevent loss of user data (i.e. NG user data or NG-U data) and / or of control data (i.e. NG application protocol data or NG-C data) during gateway switch (i.e. feeder link switch), the NG transmissions (NG-U and NG-C) between the NTN gNB and the serving AMF(s) may be suspended at the beginning of the switch procedure, and resumed at the completion of the procedure.

[0220] Thus, in addition to NG connection removal, NG connection suspension and resuming are supported.

[0221] Figure 6a is a schematic diagram 600 illustrating the protocol stack associated to the NG interface in the user plane, referred to as NG-U. This NG interface and the associated Transport Network Layer (TNL) protocol stack are described in the following 3GPP specifications: TS 38.410, TS 38.411, TS 38.414.11031371W001 The NG user plane interface (NG-U) is defined between a NG-RAN node and a UPF. It is built on IP (Internet Protocol) transport, and GTP-U (GPRS (General Packet Radio Service) Tunnelling Protocol for User Plane) 601 is used on top of UDP (User Datagram Protocol) 602 and IP 603 to carry the user plane PDUs between the NG-RAN node and the UPF.

[0222] GTP-U 601 is defined in TS 29.281, while UDP 602 is defined in IETF RFC 768, and IP 603 is defined in IETF RFC 8200 (for IPv6) and IETF RFC 791 (for IPv4).

[0223] Any data link layer 604 and physical layer 605 that fulfil the requirements toward the upper layers 601, 602, 603 may be used. For instance, they can be implemented with Ethernet protocol over fiber cables.

[0224] Figure 6b is a schematic diagram 610 illustrating the protocol stack associated to the NG interface in the control plane, referred to as NG-C. This NG interface and the associated Transport Network Layer (TNL) protocol stack are described in the following 3GPP specifications: TS 38.410, TS 38.411, TS 38.412, TS 38.413.

[0225] The NG control plane interface (NG-C) is defined between a NG-RAN node and an AMF. It is built on IP (Internet Protocol) transport, and NGAP (Next Generation Application Protocol) 611 is used on top of SCTP (Stream Control Transmission Protocol) 612 and IP 613 to carry the control plane data between the NG-RAN node and the AMF.

[0226] NGAP 611 is defined in TS 38.413, while SCTP 612 is defined in IETF RFC 4960, and IP 603 is defined in IETF RFC 8200 (for IPv6) and IETF RFC 791 (for IPv4).

[0227] Any data link layer 614 and physical layer 615 that fulfil the requirements toward the upper layers 611, 612, 613 may be used. For instance, they can be implemented with Ethernet protocol over fiber cables.

[0228] Several NGAP elementary procedures to manage a NG-C interface are specified in TS 38.413. First a NG setup procedure (described in TS 38.413 section 8.7.1) enables the establishment of a NG interface between a NG-RAN node (like WAB-gNB 542) and an AMF (like AMF 521a). This procedure shall be the first NGAP procedure triggered after the TNL association (TNLA) has become operational. For this purpose, the NG-RAN node and the AMF need to determine their IP addresses, through for instance, DNS (Domain Name System) resolution. This first TNL association shall be reserved for the NGAP elementary procedures that utilize non-UE associated signalling (i.e for generic procedures not associated to a UE).

[0229] The AMF Configuration Update procedure (described in TS 38.413 section 8.7.3) enables an AMF to provide updated configuration data to the NG-RAN node. In particular, the AMF may use it to establish additional TNL association(s) between the NG-RAN node and the AMF, or to release additional TNLA(s). Indeed, configurations with multiple SCTP endpoints per NG-RAN node / AMF11031371W001 pair should be supported. When configurations with multiple SCTP associations are supported, the AMF may request to dynamically add / remove SCTP associations between the NG-RAN node / AMF pair. Within the set of SCTP associations established between one AMF and NG-RAN node pair, the AMF may request the NG-RAN node to restrict the usage of SCTP association for certain types of NG-C signalling.

[0230] The RAN Configuration Update procedure (described in TS 38.413 section 8.7.2) enables a NG-RAN node to provide updated configuration data to the AMF. In particular, the AMF may use it to request the release of additional TNLA(s) between the NG-RAN node and the AMF.

[0231] Error Indication, AMF Status Indication, Overload Start, Overload Stop are procedures descripted in TS 38.413 respectively in sections 8.7.5, 8.7.6, 8.7.7 and 8.7.9. They allow an AMF to report information related to the current conditions of the NG interface between a NG-RAN node and the AMF.

[0232] NG Reset procedure (described in TS 38.413 section 8.7.4) can be initiated either by a NG-RAN node or by an AMF to initialise or re-initialise a NG-C interface between a NG-RAN node and an AMF.

[0233] In addition, to the above non-UE associated procedures, the UE TNLA Binding Release procedure (described in TS 38.413 section 8.13.1) enables an AMF to request an NG-RAN to release existing NGAP UE TNLA binding(s). A UE TNLA binding is the association of a UE served by the NG-RAN node and connected to the AMF, with an existing TNL association between the AMF and the NG-RAN node. It means that every NAS message exchanged between the UE and the AMF will be conveyed through a NGAP message between the NG-RAN node and the AMF using the selected TNLA. This NGAP UE TNLA binding is performed at the registration of the UE to the AMF as described in TS 23.502 section 4.2.7.2.

[0234] Other NGAP elementary procedures can be defined to support the removal, suspension, and resumption of a NG interface between a NG-RAN node and an AMF. These other procedures are described in the following figures 7a, 7b, 8a, 8b, 9a, 9b.

[0235] Figure 7a is a schematic diagram 700 showing an example message flow for performing the NG interface removal procedure between a NG-RAN node and an AMF, where the removal is initiated by the NG-RAN node.

[0236] This figure shows a NG-RAN node 701 like WAB-gNB 542 of figure 5, and an AMF 702 like the AMF 51 la of figure 5 in a 5G core network (5GC) like the core network 510 of figure 5. It can be noted that this procedure is also applicable to legacy base station or gNB like the BH-gNBl 501 of figure 5. The NG-RAN node 701 may also be embedded in a satellite, like the satellite 160 of figure 1.11031371W001 After the decision to trigger the procedure to remove the NG interface with the AMF 702, the NG-RAN node 701 sends a NG Removal Request message 703 to the AMF 702. This message is sent over the NG-C interface previously setup between this NG-RAN node 701 and the AMF 702. The message NG Removal Request message 703 may include one or more of the following information elements:

[0237] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Initiating Message;

[0238] Global RANNode ID, defined in TS 38.413 section 9.3.1.5, to identify the NG-RAN node 701;

[0239] - NG-RAN TNL Association to Remove List, containing (if present) at least one NG-RAN TNL Association to Remove Item, which may be composed of the transport layer address of the NG-RAN node 701 and the associated transport layer address of the AMF 702. Both addresses are defined in TS 38.413 section 9.3.2.6. This NG-RAN TNL Association to Remove List is used to request the remove of additional TNLA(s) existing between the NG- RAN node 701 and the AMF 702;

[0240] - UE TNLA Binding to Remove List, containing (if present) at least one UE TNLA Binding to Remove Item, which may be composed of the identifier of the associated UE at the AMF 702 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of the identifier of the associated UE at the NG-RAN node 701 (for instance with the RAN UE NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding is established when triggering the NG removal procedure;

[0241] - NG-RAN TNL Association to Keep, containing (if present) the first TNLA between the NG- RAN node 701 and the AMF 702, which was established before applying the NG setup procedure. It may be composed of the transport layer address of the NG-RAN node 701 and the associated transport layer address of the AMF 702;

[0242] Cause, to indicate the cause of NG removal. For this purpose, new values may be added to the Cause information element defined in TS 38.413 section 9.3.1.2. For instance, the Transport Layer Cause may include the values “not authorized”, “new geographical area”, “AMF change” to support this cause indication.

[0243] In NG Removal Request message 703, the information element NG-RAN TNL Association to Keep List may be considered as a network retention information element (i.e. NG-RAN and AMF related information to keep in memory of NG-RAN node 701 and AMF 702), which may also include the Global RAN Node ID of the NG-RAN node 701. Besides, the information element NG-11031371W001 RAN TNL Association to Remove List may be considered as network release information (i.e. NG-RAN and AMF related information to be deleted from memory of NG-RAN node 701 and AMF 702), and the information element UE TNLA Binding to Remove List may be considered as UE release information (i.e. UE related information to be deleted from memory of NG-RAN node 701 and AMF 702).

[0244] After reception of the NG Removal Request message 703 from the NG-RAN node 701, the AMF 702 processes the request and then sends either the NG Removal Acknowledge (or NG Removal Response) message 704 or the NG Removal Failure message 705 to the NG-RAN node 701. The NG Removal Acknowledge (or NG Removal Response) message 704 may be sent in case of successful operation (meaning the request is accepted), and the NG Removal Failure message 705 may be sent in case of unsuccessful operation (meaning the request is rejected).

[0245] The message NG Removal Acknowledge (or NG Removal Response) message 704 may include one or more of the following information elements:

[0246] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Successful Outcome;

[0247] GUAMI (a Globally Unique AMF ID), defined in TS 38.413 section 9.33.3, to identify the AMF 702;

[0248] AMF TNL Association to Remove List, containing (if present) at least one AMF TNL Association to Remove Item, which may be composed of the transport layer address of the NG-RAN node 701 and the associated transport layer address of the AMF 702. Both addresses are defined in TS 38.413 section 9.3.2.6. This AMF TNL Association to Remove List is used to request the remove of additional TNLA(s) existing between the NG-RAN node 701 and the AMF 702;

[0249] - UE TNLA Binding to Remove List, containing (if present) at least one UE TNLA Binding to Remove Item, which may be composed of the identifier of the associated UE at the AMF 702 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of the identifier of the associated UE at the NG-RAN node 701 (for instance with the RAN UE NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding is established when triggering the NG removal procedure. UE TNLA Binding to Remove List may correspond to the UE-associated Logical NG-connection List information element defined in TS 38.413 section 9.3.3.25;

[0250] AMF TNL Association to Keep, containing (if present) the first TNLA between the NG- RAN node 701 and the AMF 702, which was established before applying the NG setup11031371W001 procedure. It may be composed of the transport layer address of the NG-RAN node 701 and the associated transport layer address of the AMF 702;

[0251] Criticality Diagnostics, as defined in TS 38.413 section 9.3.1.3, to indicate parts of the NG Removal Request message 703 that have not been comprehended or were missing.

[0252] In NG Removal Acknowledge (or NG Removal Response) message 704, the information element AMF TNL Association to Keep List may be considered as network retention information element (i.e. NG-RAN and AMF related information to keep in memory of NG-RAN node 701 and AMF 702), which may also include the GUAMI of the AMF 702. Besides, the information element AMF TNL Association to Remove List may be considered as network release information (i.e. NG-RAN and AMF related information to be deleted from memory of NG-RAN node 701 and AMF 702), and the information element UE TNLA Binding to Remove List may be considered as UE release information (i.e. UE related information to be deleted from memory of NG-RAN node 701 and AMF 702).

[0253] The message NG Removal Failure message 705 may include one or more of the following information elements:

[0254] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Unsuccessful Outcome;

[0255] Cause, to indicate the cause of NG removal failure. For instance, it may be a protocol cause with a value indicating a syntax error as defined in TS 38.413 section 9.3.1.2;

[0256] Criticality Diagnostics, as defined in TS 38.413 section 9.3.1.3, to indicate parts of the NG Removal Request message 703 that have not been comprehended or were missing;

[0257] Time to wait, as defined in TS 38.413 section 9.3.1.56, to indicate a time to wait before sending a new similar request;

[0258] Alternative action, to indicate that the AMF 702 proposes another action related to the NG interface. Different values may be set for this information element: for instance, the value “reset” to propose a reset of the NG interface, or the value “suspension” to propose the suspension of the NG interface, or the value “none” to keep the current NG interface as is. NG Removal Request message 703, NG Removal Acknowledge (or NG Removal Response) message 704, and NG Removal Failure message 705 are sent using the protocol stack described at the figure 6b.

[0259] According to an embodiment of the invention the procedure 700 is a new procedure added to the NG procedures described in TS 38.413 vl8.0.0 section 8, and the messages 703, 704, 705 are new protocol messages in addition to the NG protocol messages described in TS 38.413 vl8.0.0 section 9.11031371W001 According to another embodiment of the invention, the procedure 700 is the procedure RAN Configuration Update described in TS 38.413 vl8.0.0 section 8.7.2, the message 703 is the message RAN CONFIGURATION UPDATE, the message 704 is the message RAN CONFIGURATION UPDATE ACKNOWLEDGE, and the message 705 is the message RAN CONFIGURATION UPDATE FAILURE, these 3 messages being described in TS 38.413 vl8.0.0 sections 9.2.6.4, 9.2.6.5, 9.2.6.6 respectively, with additional information elements listed in the description of the figure 7a.

[0260] According to another embodiment of the invention, the procedure 700 is the procedure NG Reset described in TS 38.413 vl8.0.0 section 8.7.4, the message 703 is the message NG RESET, the message 704 is the message NG RESET ACKNOWLEDGE, and the message 705 is the message ERROR INDICATION, these 3 messages being described in TS 38.413 V18.0.0 sections 9.2.6.11, 9.2.6.12, 9.2.6.13 respectively, with additional information elements listed in the description of the figure 7a.

[0261] Unlike the typical 5G NR scenario where the NG and Xn interfaces are operated over wired links, the WAB architecture would imply that part of the NG / Xn links is wireless (i.e., the BH link between the WAB-MT and the BH RAN node is operated over the wireless Uu interface).

[0262] Considering that the NG / Xn protocols have been designed to be operated over wired links, some countermeasures should be considered to guarantee the reliability of these interfaces when operated over a versatile wireless link, which is likely to experience link degradation or congestion.

[0263] Regardless of solutions for mitigating backhaul link degradation (i.e. backhaul link degradation management), a WAB-gNB may, at some point, decide to remove an NG connection with the Core Network (e.g., due to a change of AMF, a change of authorization status, the colocated WAB-MT entering RRC IDLE / RRC INACTIVE state ...). When initiating NG removal process, a WAB-gNB may further include in the NG Removal Request message sent to the AMF a cause value indicating the reason for requesting the NG connection removal.

[0264] Then, it can be considered that a WAB-gNB may include in the NG Removal Request message a cause value indicating the reason for requesting the NG connection removal.

[0265] Figure 7b is a schematic diagram 710 showing an example message flow for performing the procedure for NG interface removal between a NG-RAN node and an AMF, where the removal is initiated by the AMF.

[0266] This figure shows a NG-RAN node 711 like WAB-gNB 542 of figure 5, and an AMF 712 like the AMF 51 la of figure 5 in a 5G core network (5GC) like the core network 510 of figure 5. It can be noted that this procedure is also applicable to legacy base station or gNB like the BH-gNBl 50111031371W001 of figure 5. The NG-RAN node 711 may also be embedded in a satellite, like the satellite 160 of figure 1.

[0267] After the decision to trigger the procedure to remove the NG interface with the NG-RAN node 711, the AMF 712 sends a NG Removal Request message 713 to the NG-RAN node 711. This message is sent over the NG-C interface previously setup between this NG-RAN node 711 and the AMF 712. The message NG Removal Request message 713 may include one or more of the following information elements:

[0268] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Initiating Message;

[0269] GUAMI (a Globally Unique AMF ID), defined in TS 38.413 section 9.33.3, to identify the AMF 712;

[0270] AMF TNL Association to Remove List, containing (if present) at least one NG-RAN TNL Association to Remove Item, which may be composed of the transport layer address of the NG-RAN node 711 and the associated transport layer address of the AMF 712. Both addresses are defined in TS 38.413 section 9.3.2.6. This AMF TNL Association to Remove List is used to request the remove of additional TNLA(s) existing between the NG-RAN node 711 and the AMF 712;

[0271] - UE TNLA Binding to Remove List, containing (if present) at least one UE TNLA Binding to Remove Item, which may be composed of the identifier of the associated UE at the AMF 712 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of the identifier of the associated UE at the NG-RAN node 711 (for instance with the RAN UE NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding is established when triggering the NG removal procedure;

[0272] AMF TNL Association to Keep, containing (if present) the first TNLA between the NG- RAN node 711 and the AMF 712, which was established before applying the NG setup procedure. It may be composed of the transport layer address of the NG-RAN node 711 and the associated transport layer address of the AMF 712;

[0273] Cause, to indicate the cause of NG removal. For this purpose, new values may be added to the Cause information element defined in TS 38.413 section 9.3.1.2. For instance, the Transport Layer Cause may include the values “not authorized”, “new geographical area”, “AMF change” to support this cause indication.

[0274] In NG Removal Request message 713, the information element AMF TNL Association to Keep List may be considered as network retention information element (i.e. NG-RAN and AMF11031371W001 related information to keep in memory of NG-RAN node 711 and AMF 712), which may also include the GUAMI of the AMF 712. Besides, the information element AMF TNL Association to Remove List may be considered as network release information (i.e. NG-RAN and AMF related information to be deleted from memory of NG-RAN node 711 and AMF 712), and the information element UE TNLA Binding to Remove List may be considered as UE release information (i.e. UE related information to be deleted from memory of NG-RAN node 711 and AMF 712).

[0275] After reception of the NG Removal Request message 713 from the AMF 712, the NG-RAN node 711 processes the request and then sends either the NG Removal Acknowledge (or NG Removal Response) message 714 or the NG Removal Failure message 715 to the AMF node 712. The NG Removal Acknowledge (or NG Removal Response) message 714 may be sent in case of successful operation (meaning the request is accepted), and the NG Removal Failure message 715 may be sent in case of unsuccessful operation (meaning the request is rejected).

[0276] The message NG Removal Acknowledge (or NG Removal Response) message 714 may include one or more of the following information elements:

[0277] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Successful Outcome;

[0278] Global RANNode ID, defined in TS 38.413 section 9.3.1.5, to identify the NG-RAN node 711;

[0279] - NG-RAN TNL Association to Remove List, containing (if present) at least one AMF TNL Association to Remove Item, which may be composed of the transport layer address of the NG-RAN node 711 and the associated transport layer address of the AMF 712. Both addresses are defined in TS 38.413 section 9.3.2.6. This AMF TNL Association to Remove List is used to request the remove of additional TNLA(s) existing between the NG-RAN node 711 and the AMF 712;

[0280] - UE TNLA Binding to Remove List, containing (if present) at least one UE TNLA Binding to Remove Item, which may be composed of the identifier of the associated UE at the AMF 712 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of the identifier of the associated UE at the NG-RAN node 711 (for instance with the RAN UE NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding is established when triggering the NG removal procedure;

[0281] - NG-RAN TNL Association to Keep, containing (if present) the first TNLA between the NG- RAN node 711 and the AMF 712, which was established before applying the NG setup11031371W001 procedure. It may be composed of the transport layer address of the NG-RAN node 711 and the associated transport layer address of the AMF 712;

[0282] Criticality Diagnostics, as defined in TS 38.413 section 9.3.1.3, to indicate parts of the NG Removal Request message 713 that have not been comprehended or were missing.

[0283] In NG Removal Acknowledge (or NG Removal Response) message 714, the information element NG-RAN TNL Association to Keep List may be considered as network retention information element (i.e. NG-RAN and AMF related information to keep in memory of NG-RAN node 711 and AMF 712), which may also include the Global RAN Node ID of the NG-RAN node 711. Besides, the information element NG-RAN TNL Association to Remove List may be considered as network release information (i.e. NG-RAN and AMF related information to be deleted from memory of NG-RAN node 711 and AMF 712), and the information element UE TNL A Binding to Remove List may be considered as UE release information (i.e. UE related information to be deleted from memory of NG-RAN node 711 and AMF 712).

[0284] The message NG Removal Failure message 715 may include the following information elements:

[0285] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Unsuccessful Outcome;

[0286] Cause, to indicate the cause of NG removal failure. For instance, it may be a protocol cause with a value indicating a syntax error as defined in TS 38.413 section 9.3.1.2;

[0287] Criticality Diagnostics, as defined in TS 38.413 section 9.3.1.3, to indicate parts of the NG Removal Request message 713 that have not been comprehended or were missing;

[0288] Time to wait, as defined in TS 38.413 section 9.3.1.56, to indicate a time to wait before sending a new similar request;

[0289] Alternative action, to indicate that the NG-RAN node 711 proposes another action related to the NG interface. Different values may be set for this information element: for instance, the value “reset” to propose a reset of the NG interface, or the value “suspension” to propose the suspension of the NG interface, or the value “none” to keep the current NG interface as is.

[0290] NG Removal Request message 713, NG Removal Acknowledge (or NG Removal Response) message 714, and NG Removal Failure message 715 are sent using the protocol stack described at the figure 6b.

[0291] In the figures 7a and 7b, when the NG-RAN node is a WAB-gNB, the network release information may be referred to as WAB release information, and the network retention information may be referred to as WAB retention information.11031371W001 According to an embodiment of the invention the procedure 710 is a new procedure added to the NG procedures described in TS 38.413 vl8.0.0 section 8, and the messages 713, 714, 715 are new protocol messages in addition to the NG protocol messages described in TS 38.413 vl8.0.0 section 9.

[0292] According to another embodiment of the invention, the procedure 710 is the procedure AMF Configuration Update described in TS 38.413 vl8.0.0 section 8.7.3, the message 713 is the message AMF CONFIGURATION UPDATE, the message 714 is the message AMF CONFIGURATION UPDATE ACKNOWLEDGE, and the message 715 is the message AMF CONFIGURATION UPDATE FAILURE, these 3 messages being described in TS 38.413 vl8.0.0 sections 9.2.6.7, 9.2.6.8, 9.2.6.9 respectively, with additional information elements listed in the description of the figure 7b.

[0293] According to another embodiment of the invention, the procedure 710 is the procedure NG Reset described in TS 38.413 vl8.0.0 section 8.7.4, the message 713 is the message NG RESET, the message 714 is the message NG RESET ACKNOWLEDGE, and the message715 is the message ERROR INDICATION, these 3 messages being described in TS 38.413 V18.0.0 sections 9.2.6.11, 9.2.6.12, 9.2.6.13 respectively, with additional information elements listed in the description of the figure 7b.

[0294] Figure 8a is a schematic diagram 800 showing an example message flow for performing the procedure for NG interface suspension between a NG-RAN node and an AMF, where the suspension is initiated by the NG-RAN node.

[0295] This figure shows a NG-RAN node 801 like WAB-gNB 542 of figure 5, and an AMF 802 like the AMF 51 la of figure 5 in a 5G core network (5GC) like the core network 510 of figure 5. It can be noted that this procedure is also applicable to legacy base station or gNB like the BH-gNBl 501 of figure 5. The NG-RAN node 8011 may also be embedded in a satellite, like the satellite 160 of figure 1.

[0296] After the decision to trigger the procedure to suspend the NG interface with the AMF 802, the NG-RAN node 801 sends a NG Suspend Request message 803 to the AMF 802. This message is sent over the NG-C interface previously setup between this NG-RAN node 801 and the AMF 802. The message NG Suspend Request message 803 may include one or more of the following information elements:

[0297] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Initiating Message;

[0298] - Global RAN Node ID, defined in TS 38.413 section 9.3.1.5, to identify the NG-RAN node 801;11031371W001 - NG-RAN TNL Association to Remove List, containing (if present) at least one NG-RAN TNL Association to Remove Item, which may be composed of the transport layer address of the NG-RAN node 801 and the associated transport layer address of the AMF 802. Both addresses are defined in TS 38.413 section 9.3.2.6. This NG-RAN TNL Association to Remove List is used to request the remove of additional TNLA(s) existing between the NG-RAN node 801 and the AMF 802;

[0299] - UE TNLA Binding to Remove List, containing (if present) at least one UE TNLA Binding to Remove Item, which may be composed of the identifier of the associated UE at the AMF 802 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of the identifier of the associated UE at the NG-RAN node 801 (for instance with the RAN UE NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding is established when triggering the NG suspension procedure;

[0300] - NG-RAN TNL Association to Keep, containing (if present) the first TNLA between the NG- RAN node 801 and the AMF 802, which was established before applying the NG setup procedure. It may be composed of the transport layer address of the NG-RAN node 801 and the associated transport layer address of the AMF 802;

[0301] - UE TNLA Binding to Keep List, containing (if present) at least one UE TNLA Binding to Keep Item, which may be composed of the identifier of the associated UE at the AMF 802 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of the identifier of the associated UE at the NG-RAN node 801 (for instance with the RAN UE NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding is established when triggering the NG suspension procedure;

[0302] - Cause, to indicate the cause of NG suspension. For this purpose, new values may be added to the Cause information element defined in TS 38.413 section 9.3.1.2. For instance, the Transport Layer Cause may include the values “not authorized”, “new geographical area”, “AMF change”, “timer elapsed” to support this cause indication;

[0303] - Time of validity, to indicate the time to maintain the suspended status. In case a resumption of the NG interface is not triggered when this time is elapsed, then it can be considered to remove or to resume the NG interface.

[0304] In NG Suspend Request message 803, the information element NG-RAN TNL Association to Keep List may be considered as network retention information element (i.e. NG-RAN and AMF related information to keep in memory of NG-RAN node 801 and AMF 802), which may also11031371W001 include the Global RAN Node ID of the NG-RAN node 801. The information element UE TNLA Binding to Keep List may be considered as UE retention information (i.e. UE related information to keep in memory of NG-RAN node 801 and AMF 802). Besides, the information element NG-RAN TNL Association to Remove List may be considered as network release information (i.e. NG-RAN and AMF related information to be deleted from memory of NG-RAN node 801 and AMF 802), and the information element UE TNLA Binding to Remove List may be considered as UE release information (i.e. UE related information to be deleted from memory of NG-RAN node 801 and AMF 802).

[0305] After reception of the NG Suspend Request message 803 from the NG-RAN node 801, the AMF 802 processes the request and then sends either the NG Suspend Acknowledge (or NG Suspend Response) message 804 or the NG Suspend Failure message 805 to the NG-RAN node 801. The NG Suspend Acknowledge (or NG Suspend Response) message 804 may be sent in case of successful operation (meaning the request is accepted), and the NG Suspend Failure message 805 may be sent in case of unsuccessful operation (meaning the request is rejected).

[0306] The message NG Suspend Acknowledge (or NG Suspend Response) message 804 may include one or more of the following information elements:

[0307] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Successful Outcome;

[0308] - GUAMI (a Globally Unique AMF ID), defined in TS 38.413 section 9.33.3, to identify the AMF 802;

[0309] - AMF TNL Association to Remove List, containing (if present) at least one AMF TNL Association to Remove Item, which may be composed of the transport layer address of the NG-RAN node 801 and the associated transport layer address of the AMF 802. Both addresses are defined in TS 38.413 section 9.3.2.6. This AMF TNL Association to Remove List is used to request the remove of additional TNLA(s) existing between the NG-RAN node 801 and the AMF 802;

[0310] - UE TNLA Binding to Remove List, containing (if present) at least one UE TNLA Binding to Remove Item, which may be composed of the identifier of the associated UE at the AMF 802 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of the identifier of the associated UE at the NG-RAN node 801 (for instance with the RAN UE NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding is established when triggering the NG removal procedure;11031371W001 - AMF TNL Association to Keep, containing (if present) the first TNLA between the NG-RAN node 801 and the AMF 802, which was established before applying the NG setup procedure. It may be composed of the transport layer address of the NG-RAN node 801 and the associated transport layer address of the AMF 802;

[0311] - UE TNLA Binding to Keep List, containing (if present) at least one UE TNLA Binding to Keep Item, which may be composed of the identifier of the associated UE at the AMF 802 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of the identifier of the associated UE at the NG-RAN node 801 (for instance with the RAN UE NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding is established when triggering the NG suspension procedure;

[0312] - Time of validity, to indicate the time to maintain the suspension status. In case a resumption of the NG interface is not triggered when this time is elapsed, then it can be considered to remove the NG interface.

[0313] - Criticality Diagnostics, as defined in TS 38.413 section 9.3.1.3, to indicate parts of the NG Suspend Request message 803 that have not been comprehended or were missing.

[0314] In NG Suspend Acknowledge (or NG Suspend Response) message 804, the information element AMF TNL Association to Keep List may be considered as a network retention information element (i.e. NG-RAN and AMF related information to keep in memory of NG-RAN node 801 and AMF 802), which may also include the GUAMI of the AMF 802. The information element UE TNLA Binding to Keep List may be considered as UE retention information (i.e. UE related information to keep in memory of NG-RAN node 801 and AMF 802). Besides, the information element AMF TNL Association to Remove List may be considered as network release information (i.e. NG-RAN and AMF related information to be deleted from memory of NG-RAN node 801 and AMF 802), and the information element UE TNLA Binding to Remove List may be considered as UE release information (i.e. UE related information to be deleted from memory of NG-RAN node 801 and AMF 802).

[0315] The message NG Suspend Failure message 805 may include one or more of the following information elements:

[0316] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Unsuccessful Outcome;

[0317] Cause, to indicate the cause of NG suspension failure. For instance, it may be a protocol cause with a value indicating a syntax error as defined in TS 38.413 section 9.3.1.2;11031371W001 Criticality Diagnostics, as defined in TS 38.413 section 9.3.1.3, to indicate parts of the NG Suspend Request message 803 that have not been comprehended or were missing;

[0318] Time to wait, as defined in TS 38.413 section 9.3.1.56, to indicate a time to wait before sending a new similar request;

[0319] Alternative action, to indicate that the AMF 802 proposes another action related to the NG interface. Different values may be set for this information element: for instance, the value “reset” to propose a reset of the NG interface, or the value “removal” to propose the removal of the NG interface, or the value “none” to keep the current NG interface as is.

[0320] NG Suspend Request message 803, NG Suspend Acknowledge (or NG Suspend Response) message 804, and NG Suspend Failure message 805 are sent using the protocol stack described at the figure 6b.

[0321] According to an embodiment of the invention the procedure 800 is a new procedure added to the NG procedures described in TS 38.413 vl8.0.0 section 8, and the messages 803, 804, 805 are new protocol messages in addition to the NG protocol messages described in TS 38.413 vl8.0.0 section 9.

[0322] According to another embodiment of the invention, the procedure 800 is the procedure RAN Configuration Update described in TS 38.413 vl8.0.0 section 8.7.2, the message 803 is the message RAN CONFIGURATION UPDATE, the message 804 is the message RAN CONFIGURATION UPDATE ACKNOWLEDGE, and the message 805 is the message RAN CONFIGURATION UPDATE FAILURE, these 3 messages being described in TS 38.413 V18.0.0 sections 9.2.6.4, 9.2.6.5, 9.2.6.6 respectively, with additional information elements listed in the description of the figure 8a.

[0323] According to another embodiment of the invention, the procedure 800 is the procedure NG Reset described in TS 38.413 vl8.0.0 section 8.7.4, the message 803 is the message NG RESET, the message 804 is the message NG RESET ACKNOWLEDGE, and the message 805 is the message ERROR INDICATION, these 3 messages being described in TS 38.413 V18.0.0 sections 9.2.6.11, 9.2.6.12, 9.2.6.13 respectively, with additional information elements listed in the description of the figure 8a.

[0324] When the message 803 is, for example, the message RAN CONFIGURATION UPDATE or NG RESET, it may include an information element (IE) controlling the suspend and resume status of the NG transmissions. When this controlling IE is set to the value “SUSPEND”, the message RAN CONFIGURATION UPDATE or NG RESET is used to request the suspension of NG transmissions between the NG-RAN node and the AMF.11031371W001 Figure 8b is a schematic diagram 810 showing an example message flow for performing the procedure for NG interface suspension between a NG-RAN node and an AMF, where the suspension is initiated by the AMF.

[0325] This figure shows a NG-RAN node 811 like WAB-gNB 542 of figure 5, and an AMF 812 like the AMF 51 la of figure 5 in a 5G core network (5GC) like the core network 510 of figure 5. It can be noted that this procedure is also applicable to legacy base station or gNB like the BH-gNBl 501 of figure 5. The NG-RAN node 811 may also be embedded in a satellite, like the satellite 160 of figure 1.

[0326] After the decision to trigger the procedure to suspend the NG interface with the NG-RAN node 811, the AMF 812 sends a NG Suspend Request message 813 to the NG-RAN node 811. This message is sent over the NG-C interface previously setup between this NG-RAN node 811 and the AMF 812. The message NG Suspend Request message 813 may include one or more of the following information elements:

[0327] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Initiating Message;

[0328] GUAMI (a Globally Unique AMF ID), defined in TS 38.413 section 9.33.3, to identify the AMF 812;

[0329] AMF TNL Association to Remove List, containing (if present) at least one NG-RAN TNL Association to Remove Item, which may be composed of the transport layer address of the NG-RAN node 811 and the associated transport layer address of the AMF 812. Both addresses are defined in TS 38.413 section 9.3.2.6. This AMF TNL Association to Remove List is used to request the remove of additional TNLA(s) existing between the NG-RAN node 811 and the AMF 812;

[0330] - UE TNLA Binding to Remove List, containing (if present) at least one UE TNLA Binding to Remove Item, which may be composed of the identifier of the associated UE at the AMF 812 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of the identifier of the associated UE at the NG-RAN node 811 (for instance with the RAN UE NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding is established when triggering the NG removal procedure;

[0331] AMF TNL Association to Keep, containing (if present) the first TNLA between the NG- RAN node 811 and the AMF 812, which was established before applying the NG setup procedure. It may be composed of the transport layer address of the NG-RAN node 811 and the associated transport layer address of the AMF 812;11031371W001 - UE TNLA Binding to Keep List, containing (if present) at least one UE TNLA Binding to Keep Item, which may be composed of the identifier of the associated UE at the AMF 812 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of the identifier of the associated UE at the NG-RAN node 811 (for instance with the RAN UE NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding is established when triggering the NG suspension procedure;

[0332] Time of validity, to indicate the time to maintain the suspension status. In case a resumption of the NG interface is not triggered when this time is elapsed, then it can be considered to remove the NG interface.

[0333] Cause, to indicate the cause of NG suspension. For this purpose, new values may be added to the Cause information element defined in TS 38.413 section 9.3.1.2. For instance, the Transport Layer Cause may include the values “not authorized”, “new geographical area”, “AMF change”, “timer elapsed” to support this cause indication.

[0334] In NG Suspend Request message 813, the information element AMF TNL Association to Keep List may be considered as a network retention information element (i.e. NG-RAN and AMF related information to keep in memory of NG-RAN node 811 and AMF 812), which may also include the GUAMI of the AMF 812. The information element UE TNLA Binding to Keep List may be considered as UE retention information (i.e. UE related information to keep in memory of NG-RAN node 811 and AMF 812). Besides, the information element AMF TNL Association to Remove List may be considered as network release information (i.e. NG-RAN and AMF related information to be deleted from memory of NG-RAN node 811 and AMF 812), and the information element UE TNLA Binding to Remove List may be considered as UE release information (i.e. UE related information to be deleted from memory of NG-RAN node 811 and AMF 812).

[0335] After reception of the NG Suspension Request message 813 from the AMF 812, the NG-RAN node 811 processes the request and then sends either the NG Suspend Acknowledge (or NG Suspend Response) message 814 or the NG Suspend Failure message 815 to the AMF node 812. The NG Suspend Acknowledge (or NG Suspend Response) message 814 may be sent in case of successful operation (meaning the request is accepted), and the NG Suspension Failure message 815 may be sent in case of unsuccessful operation (meaning the request is rejected).

[0336] The message NG Suspend Acknowledge message 814 may include one or more of the following information elements:

[0337] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Successful Outcome;11031371W001 Global RANNode ID, defined in TS 38.413 section 9.3.1.5, to identify the NG-RAN node 811;

[0338] - NG-RAN TNL Association to Remove List, containing (if present) at least one AMF TNL Association to Remove Item, which may be composed of the transport layer address of the NG-RAN node 811 and the associated transport layer address of the AMF 812. Both addresses are defined in TS 38.413 section 9.3.2.6. This AMF TNL Association to Remove List is used to request the remove of additional TNLA(s) existing between the NG-RAN node 811 and the AMF 812;

[0339] - UE TNLA Binding to Remove List, containing (if present) at least one UE TNLA Binding to Remove Item, which may be composed of the identifier of the associated UE at the AMF 812 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of the identifier of the associated UE at the NG-RAN node 811 (for instance with the RAN UE NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding is established when triggering the NG removal procedure;

[0340] - NG-RAN TNL Association to Keep, containing (if present) the first TNLA between the NG- RAN node 811 and the AMF 812, which was established before applying the NG setup procedure;

[0341] Criticality Diagnostics, as defined in TS 38.413 section 9.3.1.3, to indicate parts of the NG Suspension Request message 813 that have not been comprehended or were missing.

[0342] In NG Suspend Acknowledge (or NG Suspend Response) message 814, the information element NG-RAN TNL Association to Keep List may be considered as a network retention information element (i.e. NG-RAN and AMF related information to keep in memory of NG-RAN node 811 and AMF 812), which may also include the Global RAN Node ID of the NG-RAN node 811. The information element UE TNLA Binding to Keep List may be considered as UE retention information (i.e. UE related information to keep in memory of NG-RAN node 811 and AMF 812). Besides, the information element NG-RAN TNL Association to Remove List may be considered as network release information (i.e. NG-RAN and AMF related information to be deleted from memory of NG-RAN node 811 and AMF 812), and the information element UE TNLA Binding to Remove List may be considered as UE release information (i.e. UE related information to be deleted from memory of NG-RAN node 811 and AMF 812).

[0343] The message NG Suspend Failure message 815 may include one or more of the following information elements:11031371W001 - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Unsuccessful Outcome;

[0344] Cause, to indicate the cause of NG suspension failure. For instance, it may be a protocol cause with a value indicating a syntax error as defined in TS 38.413 section 9.3.1.2;

[0345] Criticality Diagnostics, as defined in TS 38.413 section 9.3.1.3, to indicate parts of the NG Suspend Request message 813 that have not been comprehended or were missing;

[0346] Time to wait, as defined in TS 38.413 section 9.3.1.56, to indicate a time to wait before sending a new similar request;

[0347] Alternative action, to indicate that the NG-RAN node 811 proposes another action related to the NG interface. Different values may be set for this information element: for instance, the value “reset” to propose a reset of the NG interface, or the value “removal” to propose the removal of the NG interface, or the value “none” to keep the current NG interface as is. NG Suspend Request message 813, NG Suspend Acknowledge (or NG Suspend Response) message 814, and NG Suspend Failure message 815 are sent using the protocol stack described at the figure 6b.

[0348] In the figures 8a and 8b, when the NG-RAN node is a WAB-gNB, the network release information may be referred to as WAB release information, and the network retention information may be referred to as WAB retention information.

[0349] According to an embodiment of the invention the procedure 810 is a new procedure added to the NG procedures described in TS 38.413 vl8.0.0 section 8, and the messages 813, 814, 815 are new protocol messages in addition to the NG protocol messages described in TS 38.413 vl8.0.0 section 9.

[0350] According to another embodiment of the invention, the procedure 810 is the procedure AMF Configuration Update described in TS 38.413 vl8.0.0 section 8.7.3, the message 813 is the message AMF CONFIGURATION UPDATE, the message 814 is the message AMF CONFIGURATION UPDATE ACKNOWLEDGE, and the message 815 is the message AMF CONFIGURATION UPDATE FAILURE, these 3 messages being described in TS 38.413 vl8.0.0 sections 9.2.6.7, 9.2.6.8, 9.2.6.9 respectively, with additional information elements listed in the description of the figure 8b.

[0351] According to another embodiment of the invention, the procedure 810 is the procedure NG Reset described in TS 38.413 vl8.0.0 section 8.7.4, the message 813 is the message NG RESET, the message 814 is the message NG RESET ACKNOWLEDGE, and the message 815 is the message ERROR INDICATION, these 3 messages being described in TS 38.413 V18.0.0 sections 9.2.6.11,11031371W001 9.2.6.12, 9.2.6.13 respectively, with additional information elements listed in the description of the figure 8b.

[0352] When the message 813 is, for example, the message AMF CONFIGURATION UPDATE or NG RESET, it may include an information element (IE) controlling the suspend and resume status of the NG transmissions. When this controlling IE is set to the value “SUSPEND”, the message AMF CONFIGURATION UPDATE or NG RESET is used to request the suspension of NG transmissions between the NG-RAN node and the AMF.

[0353] Figure 9a is a schematic diagram 900 showing an example message flow for performing the procedure for NG interface resumption between a NG-RAN node and an AMF, where the resumption is initiated by the NG-RAN node.

[0354] This figure shows a NG-RAN node 901 like WAB-gNB 542 of figure 5, and an AMF 902 like the AMF 51 la of figure 5 in a 5G core network (5GC) like the core network 510 of figure 5. It can be noted that this procedure is also applicable to legacy base station or gNB like the BH-gNBl 501 of figure 5. The NG-RAN node 901 may also be embedded in a satellite, like the satellite 160 of figure 1.

[0355] After the decision to trigger the procedure to resume the NG interface with the AMF 902, the NG-RAN node 901 sends a NG Resume Request message 903 to the AMF 902. This message is sent over the NG-C interface previously setup between this NG-RAN node 901 and the AMF 902. The message NG Resume Request message 903 may include one or more of the following information elements:

[0356] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Initiating Message;

[0357] Global RANNode ID, defined in TS 38.413 section 9.3.1.5, to identify the NG-RAN node 901;

[0358] - NG-RAN TNL Association to Resume List, containing (if present) at least one NG-RAN TNL Association to Resume Item, which may be composed of the transport layer address of the NG-RAN node 901 and the associated transport layer address of the AMF 802. Both addresses are defined in TS 38.413 section 9.3.2.6. This NG-RAN TNL Association to Resume List is used to request the resumption of first and (optional) additional TNLA(s) existing between the NG-RAN node 901 and the AMF 902;

[0359] - UE TNLA Binding to Resume List, containing (if present) at least one UE TNLA Binding to Resume Item, which may be composed of the identifier of the associated UE at the AMF 902 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of the identifier of the associated UE at the NG-RAN node 901 (for instance with the RAN UE11031371W001 NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding was established when triggering the NG suspension procedure;

[0360] Cause, to indicate the cause of NG resumption. For this purpose, new values may be added to the Cause information element defined in TS 38.413 section 9.3.1.2. For instance, the Transport Layer Cause may include the values “authorized”, “new geographical area”, “AMF change”, “timer elapsed” to support this cause indication;

[0361] After reception of the NG Resume Request message 903 from the NG-RAN node 901, the AMF 902 processes the request and then sends either the NG Resume Acknowledge (or NG Resume Response) message 904 or the NG Resume Failure message 905 to the NG-RAN node 901. The NG Resume Acknowledge (or NG Resume Response) message 904 may be sent in case of successful operation (meaning the request is accepted), and the NG Resume Failure message 905 may be sent in case of unsuccessful operation (meaning the request is rejected).

[0362] The message NG Resume Acknowledge (or NG Resume Response) message 904 may include one or more of the following information elements:

[0363] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Successful Outcome;

[0364] GUAMI (a Globally Unique AMF ID), defined in TS 38.413 section 9.33.3, to identify the AMF 902;

[0365] AMF TNL Association to Resume List, containing (if present) at least one AMF TNL Association to Resume Item, which may be composed of the transport layer address of the NG-RAN node 901 and the associated transport layer address of the AMF 902. Both addresses are defined in TS 38.413 section 9.3.2.6. This AMF TNL Association to Resume List is used to request the resumption of first and (optional) additional TNLA(s) existing between the NG-RAN node 901 and the AMF 902;

[0366] - UE TNLA Binding to Resume List, containing (if present) at least one UE TNLA Binding to Resume Item, which may be composed of the identifier of the associated UE at the AMF 902 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of the identifier of the associated UE at the NG-RAN node 901 (for instance with the RAN UE NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding was established when triggering the NG suspension procedure;

[0367] Criticality Diagnostics, as defined in TS 38.413 section 9.3.1.3, to indicate parts of the NG Resume Request message 903 that have not been comprehended or were missing.11031371W001 The message NG Resume Failure message 905 may include one or more of the following information elements:

[0368] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Unsuccessful Outcome;

[0369] Cause, to indicate the cause of NG resumption failure. For instance, it may be a protocol cause with a value indicating a syntax error as defined in TS 38.413 section 9.3.1.2. Besides, a rejection of NG resumption at an AMF may be an overload status of the processing resources at the AMF, then the Transport Layer Cause may be set to the value “Transport resource unavailable”;

[0370] Criticality Diagnostics, as defined in TS 38.413 section 9.3.1.3, to indicate parts of the NG Resume Request message 903 that have not been comprehended or were missing;

[0371] Time to wait, as defined in TS 38.413 section 9.3.1.56, to indicate a time to wait before sending a new similar request;

[0372] Alternative action, to indicate that the AMF 902 proposes another action related to the NG interface. Different values may be set for this information element: for instance, the value “reset” to propose a reset of the NG interface, or the value “removal” to propose the removal of the NG interface, or the value “none” to keep the current NG interface as is.

[0373] NG Resume Request message 903, NG Resume Acknowledge (or NG Resume Response) message 904, and NG Resume Failure message 905 are sent using the protocol stack described at the figure 6b.

[0374] According to an embodiment of the invention the procedure 900 is a new procedure added to the NG procedures described in TS 38.413 vl8.0.0 section 8, and the messages 903, 904, 905 are new protocol messages in addition to the NG protocol messages described in TS 38.413 vl8.0.0 section 9.

[0375] According to another embodiment of the invention, the procedure 900 is the procedure RAN Configuration Update described in TS 38.413 vl8.0.0 section 8.7.2, the message 903 is the message RAN CONFIGURATION UPDATE, the message 904 is the message RAN CONFIGURATION UPDATE ACKNOWLEDGE, and the message 905 is the message RAN CONFIGURATION UPDATE FAILURE, these 3 messages being described in TS 38.413 vl8.0.0 sections 9.2.6.4, 9.2.6.5, 9.2.6.6 respectively, with additional information elements listed in the description of the figure 9a.

[0376] According to another embodiment of the invention, the procedure 900 is the procedure NG Setup described in TS 38.413 vl8.0.0 section 8.7.1, the message 903 is the message NG SETUP REQUEST, the message 904 is the message NG SETUP RESPONSE, and the message 905 is the11031371W001 message NG SETUP FAILURE, these 3 messages being described in TS 38.413 vl8.0.0 sections 9.2.6.1, 9.2.6.2, 9.2.6.3 respectively, with additional information elements listed in the description of the figure 9a.

[0377] When the message 903 is, for example, the message RAN CONFIGURATION UPDATE, it may include an information element (IE) controlling the suspend and resume status of the NG transmissions. When this controlling IE is set to the value “RESUME”, the message RAN CONFIGURATION UPDATE is used to request the resumption of NG transmissions between the NG-RAN node and the AMF, which were previously suspended.

[0378] Figure 9b is a schematic diagram 910 showing an example message flow for performing the procedure for NG interface resumption between a NG-RAN node and an AMF, where the resumption is initiated by the AMF.

[0379] This figure shows a NG-RAN node 911 like WAB-gNB 542 of figure 5, and an AMF 912 like the AMF 51 la of figure 5 in a 5G core network (5GC) like the core network 510 of figure 5. It can be noted that this procedure is also applicable to legacy base station or gNB like the BH-gNBl 501 of figure 5. The NG-RAN node 911 may also be embedded in a satellite, like the satellite 160 of figure 1.

[0380] After the decision to trigger the procedure to resume the NG interface with the NG-RAN node 911, the AMF 912 sends a NG Resume Request message 913 to the NG-RAN node 911. This message is sent over the NG-C interface previously setup between this NG-RAN node 911 and the AMF 912. The message NG Resume Request message 913 may include one or more of the following information elements:

[0381] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Initiating Message;

[0382] GUAMI (a Globally Unique AMF ID), defined in TS 38.413 section 9.33.3, to identify the AMF 902;

[0383] AMF TNL Association to Resume List, containing (if present) at least one AMF TNL Association to Resume Item, which may be composed of the transport layer address of the NG-RAN node 901 and the associated transport layer address of the AMF 802. Both addresses are defined in TS 38.413 section 9.3.2.6. This AMF TNL Association to Resume List is used to request the resumption of first and (optional) additional TNLA(s) existing between the NG-RAN node 911 and the AMF 912;

[0384] - UE TNLA Binding to Resume List, containing (if present) at least one UE TNLA Binding to Resume Item, which may be composed of the identifier of the associated UE at the AMF 912 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of11031371W001 the identifier of the associated UE at the NG-RAN node 911 (for instance with the RAN UE NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding was established when triggering the NG suspension procedure;

[0385] Cause, to indicate the cause of NG resumption. For this purpose, new values may be added to the Cause information element defined in TS 38.413 section 9.3.1.2. For instance, the Transport Layer Cause may include the values “authorized”, “new geographical area”, “AMF change”, “timer elapsed” to support this cause indication;

[0386] After reception of the NG Resume Request message 913 from the AMF 912, the NG-RAN node 911 processes the request and then sends either the NG Resume Acknowledge (or NG Resume Response) message 914 or the NG Resume Failure message 915 to the AMF 912. The NG Resume Acknowledge (or NG Resume Response) message 914 may be sent in case of successful operation (meaning the request is accepted), and the NG Resume Failure message 915 may be sent in case of unsuccessful operation (meaning the request is rejected).

[0387] The message NG Resume Acknowledge (or NG Resume Response) message 914 may include one or more of the following information elements:

[0388] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Successful Outcome;

[0389] Global RANNode ID, defined in TS 38.413 section 9.3.1.5, to identify the NG-RAN node 911;

[0390] - NG-RAN TNL Association to Resume List, containing (if present) at least one NG-RAN TNL Association to Resume Item, which may be composed of the transport layer address of the NG-RAN node 911 and the associated transport layer address of the AMF 912. Both addresses are defined in TS 38.413 section 9.3.2.6. This NG-RAN TNL Association to Resume List is used to request the resumption of first and (optional) additional TNLA(s) existing between the NG-RAN node 911 and the AMF 912;

[0391] - UE TNLA Binding to Resume List, containing (if present) at least one UE TNLA Binding to Resume Item, which may be composed of the identifier of the associated UE at the AMF 912 (for instance with the AMF UE NGAP ID defined in TS 38.413 section 9.3.3.1), and of the identifier of the associated UE at the NG-RAN node 911 (for instance with the RAN UE NGAP ID defined in TS 38.413 section 9.3.3.2). The presence of this information element assumes that at least one UE TNLA Binding was established when triggering the NG suspension procedure;11031371W001 Criticality Diagnostics, as defined in TS 38.413 section 9.3.1.3, to indicate parts of the NG Resume Request message 913 that have not been comprehended or were missing.

[0392] The message NG Resume Failure message 915 may include the following information elements:

[0393] - Message Type, as defined in TS 38.413 section 9.3.1.1, for instance with the value Unsuccessful Outcome;

[0394] Cause, to indicate the cause of NG resumption failure. For instance, it may be a protocol cause with a value indicating a syntax error as defined in TS 38.413 section 9.3.1.2. Besides, a rejection of NG resumption at NG-RAN node may be an overload status of the processing resources at the NG-RAN node, then the Transport Layer Cause may be set to the value “Transport resource unavailable”;

[0395] Criticality Diagnostics, as defined in TS 38.413 section 9.3.1.3, to indicate parts of the NG Resume Request message 913 that have not been comprehended or were missing;

[0396] Time to wait, as defined in TS 38.413 section 9.3.1.56, to indicate a time to wait before sending a new similar request;

[0397] Alternative action, to indicate that the NG-RAN 911 proposes another action related to the NG interface. Different values may be set for this information element: for instance, the value “reset” to propose a reset of the NG interface, or the value “removal” to propose the removal of the NG interface, or the value “none” to keep the current NG interface as is. NG Resume Request message 913, NG Resume Acknowledge (or NG Resume Response) message 914, and NG Resume Failure message 915 are sent using the protocol stack described at the figure 6b.

[0398] According to an embodiment of the invention the procedure 910 is a new procedure added to the NG procedures described in TS 38.413 vl8.0.0 section 8, and the messages 913, 914, 915 are new protocol messages in addition to the NG protocol messages described in TS 38.413 vl8.0.0 section 9.

[0399] According to another embodiment of the invention, the procedure 910 is the procedure AMF Configuration Update described in TS 38.413 vl8.0.0 section 8.7.3, the message 913 is the message AMF CONFIGURATION UPDATE, the message 914 is the message AMF CONFIGURATION UPDATE ACKNOWLEDGE, and the message 915 is the message AMF CONFIGURATION UPDATE FAILURE, these 3 messages being described in TS 38.413 V18.0.0 sections 9.2.6.7, 9.2.6.8, 9.2.6.9 respectively, with additional information elements listed in the description of the figure 9b.11031371W001 When the message 913 is, for example, the message AMF CONFIGURATION UPDATE, it may include an information element (IE) controlling the suspend and resume status of the NG transmissions. When this controlling IE is set to the value “RESUME”, the message AMF CONFIGURATION UPDATE is used to request the resumption of NG transmissions between the NG-RAN node and the AMF, which were previously suspended.

[0400] Figure 10 is a flowchart 1000 of an example method for initiating and managing at a network node (e.g. a NG-RAN node or a core network node, such as an AMF), the removal or suspension or resumption of a NG interface. For example, with reference to the communication system 500 shown in and described with respect to figure 5, the NG-RAN node may be the WAB-gNB 542, and the AMF may be the AMF 511a. The method 1000 as shown in and described with respect to figure 10 may be performed by software elements and / or hardware elements. The NG-RAN node or the AMF may be implemented in a network node 400 as shown in and described with reference to figure 4 with the method as shown in and described with respect to figure 10 being performed by an apparatus for the NG-RAN node or the AMF including one or more processing units, such as the processing unit 402.

[0401] At step 1001, the network node decides the action of removal, or suspension, or resumption of a NG interface with a remote network node. The network node executing the step 1001 may be a NG-RAN node and the remote network node is an AMF. The network node executing the step 1001 may be an AMF and the remote network node is a NG-RAN node. With the example of a mobile WAB node, like WAB node 540 in figure 5, the NG-RAN node executing the method 1000 may then be the WAB-gNB 542 and the remote network node may be the AMF 511a. Inversely, the AMF executing the method 1000 may be the AMF 511a and the remote network node may be the WAB-gNB 542.

[0402] The triggering condition for a NG removal at a NG-RAN node may be one or more of the following conditions:

[0403] - The detection of the NG-RAN node entering a new geographical area involving the need to connect to new network nodes (including a new AMF), with or without change of 5G core network, to continue to serve UEs. With the example of figure 5, this detection may be performed by the WAB-MT 541 that reads System Information Blocks (SIBs) broadcasted in serving cells. A new Tracking Area Code (TAC) included in the SIB1 indicates the change of geographical area, a new PLMN identity indicates a change of 5G core network. The information detected at WAB-MT 541 can be transferred to the WAB-gNB 542 through an internal interface between the WAB-MT 541 and the WAB-gNB 542;11031371W001 - A change of 5G core network to connect to. With the example of figure 5, this detection may be performed by the WAB-MT 541 that reads System Information Blocks (SIBs) broadcasted in serving cells. A new PLMN identity included in SIB1 indicates a change of 5G core network. The information detected at WAB-MT 541 can be transferred to the WAB- gNB 542 through an internal interface between the WAB-MT 541 and the WAB-gNB 542; - The detection of change of the authorization status of the NG-RAN node from authorized to not authorized. Using the illustration of figure 5, this indication may be provided by the AMF 521b to the WAB-MT 541 that transfers the authorization status update to the WAB- gNB 542 through an internal interface. For example, the WAB-gNB 542 is connected to the AMF 511a, and the WAB-MT is connected to the AMF 51 lb. After handover of the WAB- MT 541 from BH-gNB2 502 to BH-gNB3 503, the WAB-MT 541 connects to the AMF 521b that provides the updated authorization status. Thus, the WAB-gNB 542 may remove NG interface(s), and in particular the NG interface with AMF 511a;

[0404] - When the NG-RAN node has a MT entity entering in RRC IDLE or RRC INACTIVE state as defined in TS 38.331. For a WAB node, there may be no UEs to serve or no traffic for the served UEs, then the backhaul gNB serving the WAB-MT may decide to switch the WAB- MT to RRC IDLE or RRC INACTIVE state. The state of the WAB-MT can be indicated to the WAB-gNB;

[0405] - Expiration of a timer started when the NG interface was suspended.

[0406] The triggering for a NG removal at an AMF may be similar to the ones described at a NG-RAN node. The AMF may be informed of a new geographical area, or authorization status update, or of RRC IDLE / RRC INACTIVE state by the NG-RAN node, for instance, through the RAN Configuration Update procedure defined in TS 38.413 section 8.7.2, amended to include new information elements to indicate the status of a WAB node regarding its geographical area, authorization status, RRC state of the WAB-MT.

[0407] The triggering for a NG suspension at a NG-RAN node or an AMF may be similar to the triggers listed above for NG removal. One difference may be related to the mobility of the NG-RAN node: in case of known and / or cyclic trajectory where it is expected that the NG-RAN node may come back to the same geographical area, the existing NG interface(s) between the NG-RAN node and AMF(s) may be suspended, then to be resumed later. Thus, the trigger for NG suspension may be the detection of a new geographical area with the need to change NG interface with AMF(s), and the information related to the trajectory indicating that the NG-RAN node may come back in the same area later.11031371W001 The triggering condition for a NG resumption at a NG-RAN node may be one or more of the following conditions:

[0408] - The detection of the NG-RAN node entering a new geographical area involving the need to reconnect to network nodes (including an AMF), with or without change of 5G core network, to continue to serve UEs. With the example of figure 5, this detection may be performed by the WAB-MT 541 that reads System Information Blocks (SIBs) broadcasted in serving cells. A new Tracking Area Code (TAC) included in the SIB1 indicates the change of geographical area, a new PLMN identity indicates a change of 5G core network. The information detected at WAB-MT 541 can be transferred to the WAB-gNB 542 through an internal interface between the WAB-MT 541 and the WAB-gNB 542. In case, the WAB-gNB 542 may have suspended the NG interface with AMF 511a, and the WAB-MT 541 reconnecting to the BH- gNBl 501 may trigger the need to resume the NG interface between WAB-gNB 542 and AMF 511a;

[0409] - A change of 5G core network to connect to. With the example of figure 5, this detection may be performed by the WAB-MT 541 that reads System Information Blocks (SIBs) broadcasted in serving cells. A new PLMN identity included in SIB1 indicates a change of 5G core network. The information detected at WAB-MT 541 can be transferred to the WAB- gNB 542 through an internal interface between the WAB-MT 541 and the WAB-gNB 542; - The detection of change of the authorization status of the NG-RAN node from not authorized to authorized. Using the illustration of figure 5, this indication may be provided by the AMF 521b to the WAB-MT 541 that transfers the authorization status update to the WAB-gNB 542 through an internal interface. For example, the WAB-gNB 542 is connected to the AMF 511a, and the WAB-MT is connected to the AMF 511b. After handover of the WAB-MT 541 from BH-gNB2 502 to BH-gNB3 503, the WAB-MT 541 connects to the AMF 521b that provides the updated authorization status. Thus, the WAB-gNB 542 may resume NG interface(s), and in particular the NG interface with AMF 511a;

[0410] - When the NG-RAN node has a MT entity leaving RRC IDLE or RRC INACTIVE state and entering in RRC CONNECTED state as defined in TS 38.331. The state of the WAB- MT can be indicated to the WAB-gNB;

[0411] - Expiration of a timer started when the NG interface was suspended.

[0412] At step 1002, the network node executes preparation operations and / or procedures related to the action decided at step 1001. In case of NG removal triggered at a NG-RAN node, these operations may be the handover of UEs served by NG-RAN node, and it may include the release of11031371W001 existing UE TNLA binding(s). The step 1002 may be skipped if no particular operations have to be done.

[0413] At step 1003, the network node sends a request message to the remote network node involved in the NG interface for which the action was decided at step 1001. The request message may be the message 703, 713, 803, 813, 903, or 913 depending on the decided action (removal, suspension, or resumption) and of the initiating device (NG-RAN node or AMF).

[0414] At step 1004, the network node receives a response message from the remote network node indicating whether the request sent at step 1003 is accepted or rejected. The response message may be the message 704, 714, 705, 715, 804, 814, 805, 815, 904, 914, 905, or 915 depending on the action on the NG interface (removal, suspension, or resumption), on the sending device (NG-RAN node or AMF), and on the response (positive or negative).

[0415] At step 1005, the network node may execute the action decided at step 1001. In case of NG removal or NG suspension, this operation may consist in releasing some or all resources used to store information related to the management of the related NG interface. In case of NG resumption, this operation may consist in restoring from memory information related to the management of the related NG interface. It may consist in restoring network retention information and / or UE retention information defined with the figures 7a, 7b, 8a and 8b. This step 1005 may be skipped if the response received at step 1004 was negative. The network node may trigger a timer to disable sending a similar request during a certain amount of time (for instance 300s seconds).

[0416] The method 1000 may be limited to the steps 1003 and 1005 where the network node sends a a request message to the remote network node for NG removal or suspension or resumption of a NG interface, and the network node executes the action of NG removal or suspension or resumption of the NG interface.

[0417] Figure 11 is a flowchart 1100 of an example method for managing, at a NG-RAN node or an AMF, a request for the removal or suspension or resumption of a NG interface. For example, with reference to the communication system 500 shown in and described with respect to figure 5, the NG-RAN node may be the WAB-gNB 542, and the AMF may be the AMF 511a. The method 1100 as shown in and described with respect to figure 11 may be performed by software elements and / or hardware elements. The NG-RAN node or the AMF may be implemented in a network node 400 as shown in and described with reference to figure 4 with the method as shown in and described with respect to figure 11 being performed by an apparatus for the NG-RAN node or the AMF including one or more processing units, such as the processing unit 402.

[0418] At step 1101, the network node receives a request message from a remote network node involved in a NG interface, for the removal, or suspension or resumption of the NG interface. The11031371W001 request message may be the message 703, 713, 803, 813, 903, or 913 depending on the action (removal, suspension, or resumption) and of the initiating device (NG-RAN node or AMF).

[0419] At step 1102, the network node determining whether to accept or to reject the request. For instance, the network node may reject the request for NG resumption because of overload status of its processing resources. The network node may send a response message to the remote network node indicating whether the request is accepted or rejected. The response message may be the message 704, 714, 705, 715, 804, 814, 805, 815, 904, 914, 905, or 915 depending on the action on the NG interface (removal, suspension, or resumption), on the sending device (NG-RAN node or AMF), and on the response (positive or negative).

[0420] At step 1103, the network node may execute the action requested at step 1101 and accepted at step 1102. In case of NG removal or NG suspension, this operation may consist in releasing some or all resources used to store information related to the management of the related NG interface. In case of NG resumption, this operation may consist in restoring from memory information related to the management of the related NG interface. This step 1005 may be skipped if the response sent at step 1102 was negative.

[0421] Figure 12 is a flowchart 1200 of an example method for managing, at a NG-RAN node or an AMF, abnormal conditions at the removal or suspension or resumption of a NG interface. For example, with reference to the communication system 500 shown in and described with respect to figure 5, the NG-RAN node may be the WAB-gNB 542, and the AMF may be the AMF 511a. The method 1200 as shown in and described with respect to figure 12 may be performed by software elements and / or hardware elements. The NG-RAN node or the AMF may be implemented in a network node 400 as shown in and described with reference to figure 4 with the method as shown in and described with respect to figure 12 being performed by an apparatus for the NG-RAN node or the AMF including one or more processing units, such as the processing unit 402.

[0422] At step 1201, the network node sends a request message to the remote network node involved in the NG interface for which the action of reset, removal, suspension, or resumption was previously decided. The sent request message may be the message 703, 713, 803, 813, 903, or 913 depending on the decided action (removal, suspension, or resumption) and of the initiating device (NG-RAN node or AMF). The message may also be a NG reset message as defined in TS 38.413 section 9.2.6.11.

[0423] At step 1202, the network node receives a request message from the remote network node for the removal, or suspension or resumption of the same NG interface as the one involved in the request message sent at the step 1201. The received request message may be the message 703, 713, 803,11031371W001 813, 903, or 913 depending on the action (removal, suspension, or resumption) and of the initiating device (NG-RAN node or AMF).

[0424] At step 1203, the network node determines which request (sent or received) has priority, and then the network node processes the requests accordingly. There are several possible cases and the network node will act depending on its internal configuration to handle the various cases.

[0425] If the sent and received requests are the same, it can be considered that both requests are of equal priority. According to one aspect of the method, the network node rejects the received request (and thus may send a negative response to the remote network node), and also aborts the action corresponding to the sent request. According to another aspect of the method, a network node may have priority other another network node. For instance, an AMF may have priority over a NG-RAN node. In case the network node has priority, the received request is rejected (and a negative response may be sent to the remote network node), while the action corresponding to the sent request is processed. In case the network node has no priority, the received request is processed while the action corresponding to the sent request is aborted.

[0426] The sent and received requests may have different priority. According to one aspect of the method, the priority of a request is inherited from the priority of the initiating node. If an AMF has, for example, priority over a NG-RAN node, then the request initiating by the AMF has priority. According to another aspect of the method, an order of priority is defined among the NG procedures related to the management of NG interface. As an example, the NG reset procedure has priority over NG suspension procedure, which has priority over NG removal procedure. Also, NG resumption procedure may have priority over NG removal procedure.

[0427] In any case, when the sent request has priority, the network node may reject the received request and may process the action related to the sent request, and when the received request has priority, the network node may process the received request and may abort the action related to the sent request.

[0428] While the present invention has been described with reference to examples and embodiments, it is to be understood that the invention is not limited to the disclosed examples and embodiments. It will be appreciated by those skilled in the art that various changes and modification might be made without departing from the scope of the invention, as defined in the appended claims. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar11031371W001 purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0429] In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be advantageously used.

[0430] In the preceding embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over, as one or more instructions or code, a computer-readable medium and executed by a hardware-based processing unit.

[0431] Computer-readable media may include computer-readable storage media, which corresponds to a tangible medium such as data storage media, or communication media including any medium that facilitates transfer of a computer program from one place to another, e.g., according to a communication protocol. In this manner, computer-readable media generally may correspond to (1) tangible computer-readable storage media which is non-transitory or (2) a communication medium such as a signal or carrier wave. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, code and / or data structures for implementation of the techniques described in this disclosure. A computer program product may include a computer-readable medium.

[0432] By way of example, and not limitation, such computer-readable storage media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage, or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave may be included in the definition of medium. It should be understood, however, that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transient media, but are instead directed to nontransient, tangible storage media. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

Claims

11031371W001 CLAIMS1. A method for use in managing connectivity of a radio access network, RAN, node, connectable to an access and mobility management function, AMF, entity of a core network via a Next Generation, NG, interface, the method at the AMF entity comprising:receiving, from the RAN node, a request to suspend, resume or remove the NG interface; accepting or rejecting the request; and, in the case of accepting the request, suspending, resuming or removing the NG interface based on the request.

2. The method of claim 1, further comprising the step of:sending a response to the RAN node indicating the AMF entity has accepted or rejected the request.

3. The method of claim 2, wherein, in a case of accepting the request, the response includes one or more information element of a list comprising:a message type information element;an identification information element, wherein the value of the identification element identifies the AMF entity that has accepted the request;a network retention information element;a network release information element;a user equipment, UE, release information element;a UE retention information element; anda criticality diagnostics information element.

4. The method of claim 2, wherein, in a case of rejecting the request, the response includes one or more information element of a list comprising:a message type information element;a cause indication information element, wherein a value of the cause indication information element indicates a cause of rejection;a criticality diagnostics information element; andan alternative action information element.11031371W001 5. The method of any preceding claim, wherein the request includes one or more information element of a list comprising:a message type information element;an identification information element, wherein a value of the identification element identifies the RAN node sending the request;a cause indication information element, wherein a value of the cause indication information element indicates a cause of the request;a network retention information element;a network release information element;a user equipment, UE, release information element; anda UE retention information element.

6. The method of any preceding claim, wherein the RAN node is a wireless access and backhaul, WAB, node.

7. The method of claim 6, wherein the WAB node is a mobile WAB node.

8. The method of any preceding claim, wherein the request is a request to suspend the NG interface, and the method further comprises suspending NG transmissions between the RAN node and the AMF over the NG interface.

9. The method of any preceding claim, wherein the request is a request to resume the NG interface, and the method further comprises resuming NG transmissions between the RAN node and the AMF over the NG interface.

10. A method for use in managing connectivity of a radio access network, RAN, node, connectable to an access and mobility management function, AMF, entity of a core network via a Next Generation, NG, interface, the method at the RAN node comprising:receiving, from the AMF entity, a request to suspend, resume or remove the NG interface; accepting or rejecting the request; and, in the case of accepting the request, suspending, resuming or removing the NG interface based on the request.

11. The method of claim 10, further comprising the step of:11031371W001 sending a response to the AMF entity indicating the RAN node has accepted or rejected the request.

12. The method of claim 11, wherein, in a case of accepting the request, the response includes one or more information element of a list comprising:a message type information element;an identification information element, wherein the value of the identification element identifies the RAN node that has accepted the request;a network retention information element;a network release information element;a user equipment, UE, release information element;a UE retention information element; anda criticality diagnostics information element.

13. The method of claim 11, wherein, in a case of rejecting the request, the response includes one or more information element of a list comprising:a message type information element;a cause indication information element, wherein a value of the cause indication information element indicates a cause of rejection;a criticality diagnostics information element; andan alternative action information element.

14. The method of any of claims 10 to 13, wherein the request includes one or more information element of a list comprising:a message type information element;an identification information element, wherein a value of the identification element identifies the AMF entity sending the request;a cause indication information element, wherein a value of the cause indication information element indicates a cause of the request;a network retention information element;a network release information element;a user equipment, UE, release information element;a UE retention information element.11031371W001 15. The method of any of claims 10 to 14, wherein the RAN node is a wireless access and backhaul, WAB, node.

16. The method of claim 15, wherein the WAB node is a mobile WAB node.

17. The method of any of claims 10 to 16, wherein the request is a request to suspend the NG interface, and the method further comprises suspending NG transmissions between the RAN node and the AMF over the NG interface.

18. The method of any of claims 10 to 16, wherein the request is a request to resume the NG interface, and the method further comprises resuming NG transmissions between the RAN node and the AMF over the NG interface.

19. A method for use in managing connectivity of a radio access network, RAN, node, connectable to an access and mobility management function, AMF, entity of a core network via a Next Generation, NG, interface, the method at the AMF entity comprising:following detection of a triggering condition,sending, to the RAN node, a request to suspend, resume or remove the NG interface.

20. The method of claim 19, wherein the triggering condition is based on one or more of:detection of the RAN node entering or leaving a predetermined geographic area; detection of a change in a core network to which the RAN node is connected; detection of a change to an authorization status of the RAN node;detection of a change of a radio resource control, RRC, state of a mobile termination, MT, of the RAN node; andexpiration of a timer.

21. The method of claim 19 or 20, further comprising the steps of;receiving, from the RAN node, a response indicating whether the request is accepted or rejected; and, in the case of the request being accepted,suspending, resuming or removing the NG interface based on the response.11031371W001 22. A method for use in managing connectivity of a radio access network, RAN, node, connectable to an access and mobility management function, AMF, entity of a core network via a Next Generation, NG, interface, the method at the RAN node comprising:following detection of a triggering condition,sending, to the AMF entity, a request to suspend, resume or remove the NG interface.

23. The method of claim 22, wherein the triggering condition is based on one or more of:detection of the RAN node entering or leaving a predetermined geographic area; detection of a change in a core network to which the RAN node is connected; detection of a change to an authorization status of the RAN node;detection of a change of a radio resource control, RRC, state of a mobile termination, MT, of the RAN node; andexpiration of a timer.

24. The method of claim 22 or 23, further comprising the steps of;receiving, from the AMF entity, a response indicating whether the request is accepted or rejected; and, in the case of the request being accepted,suspending, resuming or removing the NG interface based on the response.

25. A method for use in managing connectivity of a radio access network, RAN, node, connectable to an access and mobility management function, AMF, entity of a core network via a Next Generation, NG, interface, the method at the AMF entity comprising:sending, to the RAN node, a first request to suspend, resume, reset or remove the NG interface;receiving, from the RAN node, a second request to suspend, resume, reset or remove the NG interface;comparing a priority of the first request to a priority of the second request; and suspending, resuming, resetting or removing the NG interface based on the comparison.

26. The method according to claim 25, comprising the step of:rejecting the request having the lower priority.11031371W001 27. The method of claim 25, wherein, in a case where the priority of the first request is equal to the priority of the second request, the method comprises the step of:aborting the first request.

28. The method of claim 25, wherein, in a case where the priority of the first request is equal to the priority of the second request, the method comprises the step of:rejecting the second request.

29. The method of claim 25, wherein the priority of the first and / or second request is related to at least one of:an order of priority associated with a type of entity from which the request is sent; and an order of priority associated with a type of procedure to which the request relates.

30. The method of claim 29, wherein, in the order of priority associated with a type of entity from which the request is sent, an AMF entity has priority over a RAN node.

31. The method of claim 29 or claim 30, wherein, in the order of priority associated with a type of procedure to which the request relates, an NG reset procedure has priority over an NG suspension procedure.

32. The method of any of claims 29 to 31, wherein, in the order of priority associated with a type of procedure to which the request relates, an NG suspension procedure has priority over an NG removal procedure.

33. A method for use in managing connectivity of a radio access network, RAN, node, connectable to an access and mobility management function, AMF, entity of a core network via a Next Generation, NG, interface, the method at the RAN node comprising:sending, to the AMF entity, a first request to suspend, resume, reset or remove the NG interface;receiving, from the AMF entity, a second request to suspend, resume, reset or remove the NG interface;comparing a priority of the first request to a priority of the second request; and suspending, resuming, resetting or removing the NG interface based on the comparison.11031371W001 34. The method according to claim 33, comprising the step of:rejecting the request having the lower priority.

35. The method of claim 33, wherein, in a case where the priority of the first request is equal to the priority of the second request, the method comprises the step of:aborting the first request.

36. The method of claim 33, wherein, in a case where the priority of the first request is equal to the priority of the second request, the method comprises the step of:rejecting the second request.

37. The method of claim 33, wherein the priority of the first and / or second request is related to at least one of:an order of priority associated with a type of entity from which the request is sent; and an order of priority associated with a type of procedure to which the request relates.

38. The method of claim 37, wherein, in the order of priority associated with a type of entity from which the request is sent, an AMF entity has priority over a RAN node.

39. The method of claim 37 or claim 38, wherein, in the order of priority associated with a type of procedure to which the request relates, an NG reset procedure has priority over an NG suspension procedure.

40. The method of any of claims 37 to 39, wherein, in the order of priority associated with a type of procedure to which the request relates, an NG suspension procedure has priority over an NG removal procedure.

41. A computer program comprising instructions which, when the program is executed by at least one processor unit, cause the at least one processing unit to carry out the method according to any one of claims 1 to 40.

42. A computer-readable medium carrying a computer program according to claim 41.11031371W001 41. An apparatus for a backhaul Radio Access Network, RAN, node, the apparatus comprising:one or more processing units configured to perform the method as recited in any one of claims 10 to 18, 22 to 24, and 33 to 40.

42. An apparatus for a Wireless Access Backhaul, WAB, node, the apparatus comprising:one or more processing units configured to perform the method as recited in any one of claims 10 to 18, 22 to 24, and 33 to 40.

43. An apparatus for a Access and Mobility management Function, AMF, entity, the apparatus comprising:one or more processing units configured to perform the method as recited in any one of claims 1 to 9, 19 to 21, and 25 to 32.

Images