Managing network connectivity in a wireless communication system

Abstract

Methods and apparatuses are provided for allowing a mobile wireless access backhaul mobile termination entity, MWAB-MT 311, and its collocated MWAB-gNB 312, to be connected to the same Access and Mobility management Function, AMF. This allows, by mutualizing the AMF software resources, a more efficient management of the MWAB node 310 to which the MWAB-MT and the MWAB-gNB belong. The AMF receives a request for managing connectivity from the MWAB-gNB, MWAB-MT or a backhaul gNB, BH-gNB 320. The AMF responds either accepting or rejecting the request. If the request is rejected, the response includes a cause field indicating no support for MWAB nodes and a backup field identifying another AMF that supports MWAB nodes.

Description

The present invention generally relates to managing network connectivity in a wireless communication system. Particularly, the present invention relates to managing network connectivity in a wireless communication system including at least one Wireless Access Backhaul, WAB, node. BACKGROUND 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). 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. The demand for network densification increases due to the rising number of users and higher throughput requirement. 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). 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. IAB is most likely to operate in the millimeter wave (mmWave) band to achieve the required Gbps (gigabits per second) data rate. 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). 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. 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, which base stations are referred to as mobile wireless access backhaul (MWAB) nodes, 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. 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 for new immersive applications such as AR / VR / MR gaming, e-sports, UHD 8K video, telepresence, etc. It can be noted that a MW AB node may deploy 5G Femto cells to serve UEs inside vehicles. A mobile WAB, MW AB, node includes a Mobile Terminal, MWAB-MT, which is a part used for connecting to some fixed existing infrastructure. The mobile WAB, MW AB, node also embeds a gNB, MWAB-gNB, which is used to provide backhauling connectivity as previously discussed. Upon registration to the Core Network, a Mobile Terminal, MWAB-MT, or a MWAB-gNB, of a given mobile WAB, MW AB, node may attempt to connect to an Access and Mobility Management Function (AMF) entity which does not implement some wireless access backhauling features required for efficiently operating the MW AB, node. Moreover, the Mobile Terminal, MWAB-MT, and the MWAB-gNB, of a given mobile WAB, MW AB, node may register to different AMF entities, while it may be preferable to have them both connected to one AMF entity (i.e. the same AMF entity), for ease of management purpose. Therefore, some new mechanisms are required to address at least some of the aforementioned issues, while limiting the complexity of the processing at a MW AB node as well as the latency that would result from such processing. SUMMARY According to a first aspect of the invention there is provided a method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at an access and mobility management function, AMF, entity of the at least one core network comprising: receiving a request for managing connectivity of at least one of: the gNB component, the MT component, and a backhaul gNB associated with the WAB node; accepting or rejecting the request for managing connectivity, based on received information associated with the WAB node; sending a response indicating the AMF entity has accepted or rejected the request for managing connectivity. Optionally, the received information includes at least one of: information indicating the WAB node is a mobile WAB node; information indicating the WAB node supports local services; information identifying a gNB component of the WAB node co-located with a mobile termination component of the WAB node; and context information associated with the WAB node. Optionally, in a case of accepting the request for managing connectivity, the response includes an identification field, and wherein the value of the identification field identifies the AMF entity that has accepted the request. Optionally, in a case of rejecting the request for managing connectivity, the response includes a cause field, and wherein the value of the cause field indicates a cause of the rejection. Optionally, the value of the cause field is selected from a set of predefined values including a value to indicate that the AMF entity does not support mobile WAB nodes. Optionally, the response further includes an AMF backup field, and wherein the value of the AMF backup field identifies another AMF entity that supports mobile WAB nodes. Optionally, receiving a request for managing connectivity comprises receiving a request, from a backhaul gNB associated with the WAB node, for managing connectivity of the gNB component or the MT component. Optionally, receiving a request for managing connectivity comprises receiving a request, from the WAB node, for managing connectivity of the gNB component or the MT component. Optionally, sending a response comprises sending a response to the WAB node. Optionally, sending a response comprises sending a response to the backhaul gNB. Optionally, sending a response comprises sending a response to another AMF entity supporting mobile WAB nodes. Optionally, receiving a request for managing connectivity comprises receiving a request, from a backhaul gNB associated with the WAB node, for managing connectivity of the backhaul gNB associated with the WAB node, and wherein sending a response comprises sending a response to the backhaul gNB. According to a second aspect of the invention there is provided a method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at the backhaul gNB comprising: receiving, from a first access and mobility management function, AMF, entity of the at least one core network, information associated to a second AMF entity; and sending, to the WAB node, the information associated to the second AMF entity. Optionally, the second AMF is capable of serving the WAB node. Optionally, the information associated to the second AMF entity includes at least one of: an identifier of the second AMF entity, and a cause for sending the information. Optionally, the method further comprises the step of: performing a connection procedure with the second AMF entity. Optionally, the step of sending, to the WAB node, the information associated to the second AMF entity comprises forwarding the information to the MT component of the WAB node. Optionally, the step of forwarding the information to the MT component of the WAB node comprises forwarding the information through a connection information message. Optionally, the step of sending, to the WAB node, the information associated to the second AMF entity comprises broadcasting the information the MT components of all mobile WAB nodes in the vicinity of the backhaul gNB. According to a third aspect of the invention there is provided a method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at the WAB node comprising: sending, by the gNB component, connection information to a base station connected to a first access and mobility management function, AMF, entity of the at least one core network, wherein said connection information is associated to a second AMF entity capable of serving the WAB node. Optionally, the step of sending the connection information comprises sending, by the gNB, the connection information to the MT component, and forwarding, by the MT component, the connection information to the base station. Optionally, the connection information is forwarded by the MT component via a network information message. According to a fourth aspect of the invention there is provided a method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at the backhaul gNB comprising: receiving, from the MT component, information associated to a second access and mobility management function, AMF, entity of the at least one core network; and sending, to a first AMF entity to which the backhaul gNB is already connected, the information associated to the second AMF entity. Optionally, the step of sending, to a first AMF entity to which the backhaul gNB is already connected, the information associated to the second AMF entity comprises sending a reconfiguration message to the first AMF entity. Optionally, the information associated to the second AMF entity includes an identifier of the second AMF entity. Optionally, the method further comprises the step of: performing a connection procedure with the second AMF entity. According to a fifth aspect of the invention there is provided a method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at the WAB node comprising: sending, to a first access and mobility management function, AMF, entity of the at least one core network, connection information, wherein said connection information is associated to a second AMF entity capable of serving the WAB node. Optionally, the step of sending connection information is performed by the gNB component. Optionally, the information is received by the gNB component from the MT component prior to sending. Optionally, the MT component is connected to the second AMF entity. Optionally, the connection information includes at least one of: an identifier of the second AMF entity, and an identifier of the backhaul gNB. According to a sixth aspect of the invention there is provided a method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at a first access and mobility management function, AMF, entity of the at least one core network comprising: receiving, from the gNB component, connection information, wherein said connection information is associated to a second AMF entity capable of serving the MT component. Optionally, the connection information includes at least one of: an identifier of the second AMF entity, and an identifier of the backhaul gNB. Optionally, the method further comprises the step of: sending, to the second AMF entity, at least one of: an identifier of the first AMF entity, and an identifier of the backhaul gNB. Optionally, the method further comprises the step of: performing a connection procedure with the second AMF entity, in which the gNB component is connected to the second AMF entity. Optionally, the method further comprises the step of: performing a connection procedure, in which the MT component is connected to the first AMF entity. According to a seventh aspect of the invention there is provided method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at a first access and mobility management function, AMF, entity of the at least one core network comprising: receiving, from a second AMF entity, information for connecting a backhaul base station served by the second AMF entity to the first AMF entity. Optionally, the information includes at least one of: an identifier of the second AMF entity, and an identifier of the backhaul base station served by the second AMF entity. Optionally, the method further comprises the step of: sending, to the backhaul base station served by the second AMF entity, a reconfiguration request message. Optionally, the reconfiguration request message includes an identifier of the first AMF entity. According to an eighth aspect of the invention there is provided a method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at the backhaul gNB comprising: receiving, from a first access and mobility management function, AMF, entity of the at least one core network to which the backhaul gNB is currently connected, information for connecting the backhaul gNB to a second AMF entity. Optionally, the information includes an identifier of the second AMF entity. Optionally, the method further comprises the step of: performing a connection procedure to connect the backhaul gNB to the second AMF entity. Optionally, in any of the preceding aspects of the invention, the WAB node is a mobile wireless access backhaul, MW AB, node. According to a ninth 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 of the first to eighth aspects. According to a tenth aspect of the invention there is provided a computer-readable medium carrying a computer program according to the ninth aspect. According to an eleventh aspect of the invention there is provided an apparatus for a backhaul Radio Access Network, RAN, node, the apparatus comprising: one or more processing units configured to perform the method according to the second, fourth or eighth aspect. According to a twelfth aspect of the invention there is provided an apparatus for a Wireless Access Backhaul, WAB, node, the apparatus comprising: one or more processing units configured to perform the method according to the third or fifth aspect. According to a thirteenth aspect of the invention there is provided an apparatus for an Access and Mobility management Function, AMF, entity, the apparatus comprising: one or more processing units configured to perform the method according to the first, sixth or seventh aspect. BRIEF DESCRIPTION OF THE DRAWINGS Different aspects of the invention will now be described, by way of example only, and with reference to the following drawings in which: Figure 1 is a schematic diagram illustrating an example wireless communication system in which the present invention may be implemented according to one or more example embodiments; Figures 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; Figures 3 is a simplified schematic diagram of a 5G system involving a Mobile Wireless Access Backhaul (MWAB) node, and in which the present invention may be implemented according to one or more example embodiments; Figure 4 shows a block schematic diagram of an example network node or base station in accordance with one or more embodiments of the present invention; Figure 5 is a simplified schematic diagram showing an example of a wireless communication system, including a Wireless Access Backhaul (WAB) network of WAB network system, in which embodiments and examples of embodiments of the present invention may be implemented; Figure 6 to Figure 12 are schematic and simplified diagrams illustrating example message flows for use in managing network connectivity in a wireless communication system including at least one Wireless Access Backhaul, WAB, node in accordance with one or more embodiments of the invention; and Figure 13 to 16d are flowcharts illustrating example methods performed at a Wireless Access Backhaul system entity in accordance with one or more embodiments of the present invention. DETAILED DESCRIPTION Figure 1 illustrates an example communication system 100 in which the present invention may be implemented according to one or more embodiments. 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 5GNR 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. The system 100 comprises a plurality of UEs (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 Mobile Wireless Access Backhaul (MWAB) 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 MW AB node. In more general terms, the MW AB 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 MW AB node is implemented in a 5G femto network, the MW AB 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.). 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 cameras (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. Base stations 102, 103 and 104 are interconnected through a wired link infrastructure 180, preferably based on optical fiber or any other wired means. 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 V18.0.0 specification document. 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 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 MW AB nodes, or MWAB-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, MWAB-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 MWAB-node (e.g., Ues 151, 152, 153 and 154 connected to MW AB node 150). The base stations 102, 103 and 104, the MWAB 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 MWAB network (also referred to as MWAB topology), which accommodates UEs 111, 112, 113, 121, 122, 123, 131, 132, 133, 134, 141, 142, 143, 151, 152, 153 and 154. The terms WAB network, MWAB network, WAB topology and MWAB 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. The base stations 102, 103 and 104, the MW AB 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 MW AB system, which accommodates UEs 111, 112, 113, 121, 122, 123, 131, 132, 133, 134, 141, 142, 143, 151, 152, 153 and 154. The terms WAB system and MW AB 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, MAC and physical layer protocols. The MW AB 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 D1601a and D1601b). ). Although a single logical hop is shown in Figure 1, it will be appreciated that the MW AB nodes could be wirelessly backhauled to the base station over multiple logical hops (for example, similar to the multiple hops provided in an IAB network). Each MW AB node consists or includes a gNB or RAN node or base station component or entity which is referred to as a MWAB-gNB, or MW AB base station, and Mobile Termination (MT) component or entity which is referred to as an MWAB-MT, or MWAB-Mobile Termination. The MWAB-gNB functionality on an MWAB-node allows or enables the MWAB-node to serve UEs. The MWAB-MT functionality includes, e.g., physical layer, layer-2, RRC and Non-Access Stratum (NAS) functionalities and allows or enables the MWAB-MT to connect to a fixed base station, or gNB, such as base station 102, 103 or 104. MW AB 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 MW AB 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). MW AB 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 DI700 to the Core Network 170 through the wired link infrastructure 190, which is preferably based on optical fiber or any other wired means. 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. 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. An AMF 212 is responsible for handling registration, authentication, connection and mobility management tasks for a UE. 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. 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. 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 Nil 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. 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). Figure 3 is a simplified schematic diagram of a 5G system 300 involving a Mobile Wireless Access Backhaul (MWAB) 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 MWAB node 310 through the Uu interface. The MW AB node 310 is composed of or includes a MT or MWAB-MT unit / component / entity 311 (also called MW AB-UE), and a gNB or MWAB-gNB unit / component / entity 312. Through the MWAB-gNB 312, a MWAB 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 MWAB node 310 (e.g. on entering / leaving the vehicle). In other words, the MWAB-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 MWAB 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 MWAB-MT 311 via a gNB 320, which can be called a backhaul RAN node, backhaul base station, backhaul gNB or BH gNB. Acting as a legacy UE, the MWAB-MT 311 connects via a NG-RAN cell of the BH gNB 320, through a backhaul link that may be a direct link or via a satellite (e.g. when the MWAB node 310 is embedded in an airplane). Thus, a PDU session is provided either by a Terrestrial Network (TN) or by a Non-Terrestrial Network (NTN). In addition, the MWAB 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 MW AB node 310 includes a UPF 313, the MW AB node can connect to one or more local servers (e.g. mounted at the same entity as the MW AB 310) enabling a UE served by the MW AB access to local services provided by the local servers with no traffic required outside of the MW AB node / server environment. The BH gNB 320 provides N3 and N2 interfaces so that the MWAB-MT 311 can access to the functions of its 5G core network 330. Indeed, a MWAB-MT 311 may have access to some or several PLMNs through the appropriate subscriptions, and it may connect in a nonroaming 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 MWAB-MT 311 interacts with the AMF 332, which can be called the MW AB AMF, and establishes PDU session(s) with the UPF 331, which can be called the MW AB UPF. The MW AB UPF 331 is controlled by the SMF 333 (through N4 interface), which can be called the MW AB SMF, and which also interacts with the MW AB AMF 332 (through Nil interface). There may be one or several intermediate UPFs between the BH gNB 320 and the MW AB UPF 331 as mentioned in the Figure 2. An interface internal to the MW AB node 310 exists between the MWAB-gNB 312 and the MWAB-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. Once the MWAB-MT 311 has established a PDU session with the MWAB UPF 331, the MW AB node is ready to serve UEs and the MWAB-gNB 312 can start operating as a legacy gNB. The MWAB-gNB may support various PLMNs and the UE 301 connects to one PLMN, e.g. PLMN2, which may be different from the PLMN1 the MWAB-MT 311 connects to. In the case where PLMN1 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 MWAB UPF 331, the MWAB AMF 332, and the MWAB SMF 333 belong to the same 5G core network 350. In addition, the UE UPF 341 and the MWAB UPF 331 may be the same UPF, the UE AMF 342 and the MWAB AMF 332 may be the same AMF, the UE SMF 343 and the MWAB SMF 333 may be the same SMF. 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 MW AB UPF 331, and thanks to the N6 interface between the MW AB UPF 331 and the UE AMF 342. These N6 interfaces enable the establishment of N2 interface between the MWAB-gNB 312 and the UE AMF 342, and the establishment of N3 interface between the MWAB-gNB 312 and the UE UPF 341, which allows the UE 301 to access the Data Network 360. In case the MWAB-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 MW AB 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. In case the MWAB-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 MW AB UPF 331 directly connects to the UE UPF 341 and the UE AMF 342 through N6 interfaces as shown in the Figure 3. 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 MW AB nodes shown in Figure 1, in accordance with one or more embodiments of the invention. Each of a MW AB node 110, 120a, 120b, 130, 140, or 150 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. 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. 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 XbnAP protocol) with other base station of the Radio Access Network (RAN), all defined by the 3GPP standard. The network interface 432 may not be present or active in case the base station 400 is a MW AB 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. 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 1041b between base station 104 and the MT / UE unit of MW AB node 120b, or link 1202 between the gNB unit of MW AB node 120b and the UE 122. In case of MW AB 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 MW AB 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. 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 may include information associated with the mobile WAB node, such as information elements 420 related to a MW AB node, including the authorization status of the mobile WAB node. The information elements 420 may be associated to the base station 400 (when the base station is a MW AB node), and may be communicated to any network node when necessary. The information elements may also be related to a MW AB node (which is not the base station 400), and stored after reception from the MW AB node or from another network node. The operation of the information elements 420 will be described in more detail below. Specific program elements / sub-routines stored in program memory may include one or more of the following: elements for sending a request for a backhaul RAN node or an AMF entity to serve a WAB node, the request including information associated with the WAB node, elements for receiving a request for serving a WAB node and for receiving information associated with the WAB node, an element for accepting or rejecting the request for serving the WAB node based on the received information, an element for sending a response and provide information, the response including information to be used for connecting a WAB node (see, for example, the methods described below with reference to figures 6-16d). 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. 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. In a 5G core network, an AMF (Access and Mobility management Function) like the MW AB 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. 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. 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. 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, 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 MW AB nodes 530 and 540. 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). As discussed above, each MW AB node comprises a Mobile Termination (MT) part or unit (MWAB-MT 531 for MW AB node 530 and MWAB-MT 541 for MWAB node 540) and a RAN node or base station part or unit (MWAB-gNB 532 for MWAB node 530 and MWAB-MT 542 for MWAB node 540). MWAB node 530 and MWAB node 540 may also embed a UPF entity, respectively UPF entity 533 and UPF 543, as previously discussed in Figure 3, allowing MWAB-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. MWAB node 530 is connected to the serving backhaul base station referred to as BH-gNB 1,501 through BH link 5011. MW AB 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. MWAB-gNB 532 of MW AB 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. Similarly, MWAB-gNB 542 of MW AB node 540 is also connected to UE 561 through communication link or radio link 5401. Although Figure 5 shows only UE 561 connected to MW AB node 540, it will be appreciated that there will be a plurality of UEs connected to MW AB nodes of the wireless communication system. MWAB-gNB 532 and MWAB-MT 531 may be connected to a same AMF function or entity (e.g., AMF 51 la) 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). Some AMF functions may be implementing MWAB-specific features for managing a MW AB node (e.g., advanced mobility features). Some AMF functions may not implement such features but may still be capable of serving a MW AB node with a limited set of basic features. Some AMF functions may not be capable of serving a MW AB node. The processes and arrangements for managing one or more network connections and managing mobile WAB node authorization in a wireless communication system including one or more mobile WAB (MWAB) nodes will now be described according to some embodiments of the present invention. It should be noted that, although much of the following detailed description of examples of embodiments of the invention with respect to Figs. 6-16d describes mobile Wireless Access Backhaul, WAB, nodes (or MW AB nodes), the invention may also be applied to Wireless Access Backhaul, WAB, nodes generally, including fixed WAB nodes (e.g. WAB node 130, shown in Fig. 1), as these nodes have the same architecture as MW AB nodes and only differ in that the nodes are non-mobile (i.e. stationary). In other words, the invention may broadly be applied to any WAB node (i.e. mobile or fixed, Femto or non-Femto, etc.). Therefore, it will be appreciated that mentions of “MWAB” in the following description (e.g. in terms such as “MWAB information”, “MWAB node”, “MWAB-MT”, “MWAB-gNB”, “MWAB indication”, “MWAB local services support”, “MWAB co-location”, capability”, etc.) may simply be substituted by the relevant WAB equivalent. “MWAB-gNB Figure 13 is a flowchart of an example method 1300 for managing a Wireless Access Backhaul, WAB, node connectivity according to one or more embodiments of the present invention. The method 1300 of Figure 13 is performed by an AMF Core Network entity. For example, with reference to the wireless communication system shown in and described with respect to Figure 5, the AMF entity performing the method 1300 may be the AMF entity 511a. This AMF entity may be serving a BH gNB node, which may be the base station 501, while the MWAB node attempting to connect to the AMF 51 la through the BH gNB 510 may be the MWAB node 530 (which comprises MWAB-MT 531 and MWAB-gNB 532), of WAB system 500. The method 1300 as shown in and described with respect to Figure 13 may be performed by software elements and / or hardware elements. The MWAB node may be implemented in a communication device 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 one or more processing units, such as the processing unit 402. Briefly, in a first step 1301, an AMF Core Network entity receives a connection request from a wireless access backhaul system entity. This connection request message may include some MWAB information related to the capability of the wireless access backhaul system entity, as discussed in Figures 6 and 8. In one example, the wireless access backhaul system entity is the MWABMT of a wireless access backhaul node and the connection request received by the AMF Core Network entity is the REGISTRATION REQUEST message 602, as discussed in Figure 6. In one example, the wireless access backhaul system entity is the MWAB-gNB of a wireless access backhaul node and the connection request received by the AMF Core Network entity is the SETUP REQUEST message 701, as discussed in Figure 7. In one example, the wireless access backhaul system entity is a backhaul gNB, or BH-gNB, and the connection request received by the AMF Core Network entity is the SETUP REQUEST message 801, as discussed in Figure 8. In a second step 1302, the AMF Core Network entity may, in response to the previously received connection request, send to a wireless access backhaul system entity some alternate connection information associated to a Core Network entity which is capable of serving one or more wireless access backhaul nodes. In one example, the alternate connection information 22 may include at least one of: an identifier of an AMF Core Network entity, the cause for sending the alternate connection information (e.g., the AMF Core Network entity does not support MWAB-specific features, such as mobility management, or the AMF Core Network entity cannot accept the load associated to a MW AB node). Some further cause information is discussed in relation with Figure 6. In one example, in relation with Figure 8, the wireless access backhaul system entity that receives the alternate connection information from the AMF Core Network entity is the backhaul base station that issued the connection request in step 1301. In one example, in relation with Figure 6, the wireless access backhaul system entity that receives the alternate connection information from the AMF Core Network entity is the backhaul base station serving the MWAB-MT entity that issued the connection request and that forwarded this connection request to the AMF Core Network entity in step 1301. In one example, in relation with Figure 7, the wireless access backhaul system entity that receives the alternate connection information from the AMF Core Network entity is the MWAB-gNB entity that issued the connection request in step 1301. In one example, the AMF entity may send the alternate connection information when it is not capable of managing any MW AB node, for instance because it does not support some wireless access backhaul specific features (e.g., mobility management features) required to handle the a MW AB node. In one example, the AMF entity may send the alternate connection information when it is not capable of managing the requesting MWAB-MT, for instance because it does not support some wireless access backhaul specific features (e.g., mobility management features) required to handle the MWAB-MT, or because it cannot support the load associated to the wireless access backhaul node. In one example, the AMF Core Network entity may send the alternate connection information through a REGISTRATION RESPONSE message 603 sent to the BH-gNB serving the MWAB-MT, as discussed in Figure 6. In one example, the AMF Core Network entity may send the alternate connection information through a SETUP RESPONSE message 702 sent to the BH-gNB serving the MWAB-MT, as discussed in Figure 7. In one example, the AMF Core Network entity may send the alternate connection information through a SETUP RESPONSE message 802 sent to the BH-gNB that issued the connection request, as discussed in Figure 8. Figure 14 illustrates an example method 1400, performed by a backhaul base station such as base station 501 of Figure 5, for managing Wireless Access Backhaul, WAB, connectivity according to one or more embodiments of the present invention. For example, with reference to the wireless communication system shown in and described with respect to Figure 5, the AMF entities involved in the method 1400 may be the AMF entity 511a serving the BH gNB node 501 or the AMF 511b, while the MW AB node involved in method 1400 may be the MW AB node 530 (which comprises MWAB-MT 531 and MWAB-gNB 532), of WAB system 500. Briefly, in a first step 1401, a backhaul base station may receive from a first AMF Core Network entity some alternate connection information associated to a second AMF Core Network entity capable of serving one or more wireless access backhaul nodes. In one example, the alternate connection information includes at least one of: an identifier of the second AMF Core Network entity, the cause for sending the alternate connection information (e.g., the AMF Core Network entity does not support MWAB-specific features, such as mobility management, or the AMF Core Network entity cannot accept the load associated to a MW AB node). Some further cause information is discussed in relation with Figure 7. In one example, the first AMF Core Network entity is different from the second AMF Core Network entity (e.g., the first AMF Core Network entity is AMF 511a and the second AMF Core Network entity is AMF 512a). In one example, the first Core Network entity and the second Core Network entity are the same (e.g., AMF Core Network entity AMF 511a). In one example, when the connection information is destined to the backhaul base station, and in case the second AMF Core Network entity is different from the first AMF Core Network entity, the backhaul base station may further attempt to connect to the second AMF Core Network entity by performing a connection procedure, as discussed in Figure 8. In one aspect of the invention, and in relation with Figure 6, the backhaul base station may send to one or more wireless access backhaul nodes some alternate communication information associated to the second AMF Core Network entity. In one example, when the alternate connection information is destined to the MWAB-MT of a wireless access backhaul node, the backhaul base station may, in step 1402, forward all or part of the connection information to this MWAB-MT through a CONNECTION INFORMATION message 604, as discussed in Figure 6. In another example, in step 1402, the backhaul base station may share all or part of the alternate connection information received at step 1401 to all or part of the MWAB-MT entities it is serving through a CONNECTION INFORMATION message 604, as discussed in Figure 6. In another example, in step 1402, the backhaul base station may broadcast all or part of the connection information received at step 1401 to the MWAB-MT entities in its vicinity through a NETWORK INFORMATION message 901, as discussed in Figure 9. Figure 15a is a flowchart of an example method 1500a for managing a Wireless Access Backhaul, WAB, node connectivity according to one or more embodiments of the present invention. The method 1500a of Figure 15a is performed at the mobile Wireless Access Backhaul, MW AB, node. For example, with reference to the wireless communication system shown in and described with respect to Figure 5, the MW AB node performing the method 1500a may be the MWAB-node 530, which comprises MWAB-MT 531 and MWAB-gNB 532, of WAB system 500. The method 1500a as shown in and described with respect to Figure 15a may be performed by software elements and / or hardware elements. The MW AB node may be implemented in a communication device 400 as shown in and described with reference to Figure 4 with the method as shown in and described with respect to Figure 15a being performed by one or more processing units, such as the processing unit 402. Briefly, in a first step 1501a, the MWAB-gNB of a Wireless Access Backhaul, MW AB, node may send to a base station connected to a first AMF Core Network entity, such as AMF 511a of Figure 5, some alternate connection information associated to a second Core Network entity which is capable of serving the wireless access backhaul node. Such information may have been received from its collocated MWAB-MT as a result of any of the methods in relation with any of the Figures 6, 7, 8, 9, 13 or 14. Further details on the alternate connection information are discussed in Figure 10. In one example, the alternate connection information may be passed by the MWAB-gNB to its collocated MWAB-MT through the NETWORK INFORMATION message 1003 so that the MWAB-MT forwards it through the NETWORK INFORMATION message 1004 to its serving base station, as discussed in Figure 10. Details on the alternate connection information are also further discussed in relation with Figure 10. In one example, the alternate connection information may include an identifier of the second AMF Core Network entity. Figure 15b is a flowchart of an example method 1500b for managing a Wireless Access Backhaul, WAB, node connectivity according to one or more embodiments of the present invention. The method 1500b of Figure 15b is performed at the backhaul base station, BH-gNB. For example, with reference to the wireless communication system shown in and described with respect to Figure 5, the backhaul base station performing the method 1500b may be the base station 501 of WAB system 500. The method 1500b as shown in and described with respect to Figure 15b may be performed by software elements and / or hardware elements. The backhaul base station node may be implemented in a communication device 400 as shown in and described with reference to Figure 4 with the method as shown in and described with respect to Figure 15b being performed by one or more processing units, such as the processing unit 402. Briefly, in a first step 1501b, a backhaul base station may receive from a MWAB-MT some alternate connection information, as previously discussed in relation with step 1501a of Figure 15a. The backhaul base station may forward this alternate connection information to a first AMF Core Network entity to which it is connected, such as AMF 511a, using the RECONFIGURATION message 1005, as discussed in Figure 10. In one example, the alternate connection information to be forwarded is associated to a second AMF Core Network entity, such as AMF 51 lb, which is capable of serving the wireless access backhaul node the MWABMT belongs to. In one example, the alternate connection information is an identifier of the second AMF Core Network entity. Then, in step 1502b, the backhaul base station may connect to the second AMF Core Network entity by issuing a SETUP REQUEST message 1007, as discussed in Figure 10. In one example, the backhaul base station may wait for the reception of a RECONFIGURATION ACKNOWLEDGE message 1006 before connecting to the second AMF Core Network entity by issuing a SETUP REQUEST message 1007, as discussed in Figure 10. Methods 1500a and 1500b may thus allow a MWABMT and its collocated MWAB-gNB to be connected to the same AMF Core Network entity, which would allow, by mutualizing the AMF software resources, a more efficient management of the mobile wireless access backhaul, MW AB, node to which the MWABMT and the MWAB-gNB belong. Figure 16a is a flowchart of an example method 1600a for managing a Wireless Access Backhaul, WAB, node connectivity according to one or more embodiments of the present invention. The method 1600a of Figure 16a is performed at the mobile Wireless Access Backhaul, MW AB, node. For example, with reference to the wireless communication system shown in and described with respect to Figure 5, the MW AB node performing the method 1600a may be the MWAB-node 530, which comprises MWAB-MT 531 and MWAB-gNB 532, of WAB system 500. The method 1600a as shown in and described with respect to Figure 16a may be performed by software elements and / or hardware elements. The MW AB node may be implemented in a communication device 400 as shown in and described with reference to Figure 4 with the method as shown in and described with respect to Figure 16a being performed by one or more processing units, such as the processing unit 402. Briefly, in a first step 1601a, the MWAB-gNB sends to a first AMF Core Network entity, such as AMF 511a of Figure 5, some alternate connection information associated to a second Core Network entity which is capable of serving the wireless access backhaul node. Such information may have been received from its collocated MWAB-MT as a result of any of the methods in relation with any of the Figures 6, 7, 8, 9, 13 or 14. Further details on the alternate connection information are discussed in Figure 11. In one example, the alternate connection information may be passed by the MWAB-gNB to first AMF Core Network entity through the SETUP REQUEST message 1102, as discussed in Figure 11. Details on the alternate connection information are also further discussed in relation with Figure 11. In one example, the alternate connection information may include at least one of: an identifier of the second AMF Core Network entity, an identifier of the backhaul base station that is serving the mobile terminal part of the wireless access backhaul node, or MWAB-MT. In one example, the second AMF Core Network entity is the AMF Core Network entity that is serving the mobile terminal part of the wireless access backhaul node, or MWAB-MT. Figure 16b is a flowchart of an example method 1600b for managing a Wireless Access Backhaul, WAB, node connectivity according to one or more embodiments of the present invention. The method 1600b of Figure 16b is performed at the AMF Core Network entity. For example, with reference to the wireless communication system shown in and described with respect to Figure 5, the AMF entity performing the method 1600b may be the AMF entity 511a. This AMF entity may be serving a BH gNB node, which may be the base station 501, while the MW AB node attempting to connect to the AMF 511a through the BH gNB 510 may be the MW AB node 530 (which comprises MWAB-MT 531 and MWAB-gNB 532), of WAB system 500. The method 1600b as shown in and described with respect to Figure 16a may be performed by software elements and / or hardware elements. The MW AB node may be implemented in a communication device 400 as shown in and described with reference to Figure 4 with the method as shown in and described with respect to Figure 16b being performed by one or more processing units, such as the processing unit 402. Briefly, in a first step 1601b, a first AMF Core Network entity receives from the base station part of a wireless access backhaul node, or MWAB-gNB, a connection request message which includes some alternate connection information associated to a second AMF Core Network entity which is capable of serving the mobile terminal part of the wireless access backhaul node, or MWAB-MT. In one example, the alternate connection information may be passed by the MWAB-gNB to the first AMF Core Network entity through the SETUP REQUEST message 1102, as discussed in Figure 11. Details on the alternate connection information are also further discussed in relation with Figure 11. In one example, the alternate connection information may include at least one of: an identifier of the second AMF Core Network entity, an identifier of the backhaul base station that is serving the mobile terminal part of the wireless access backhaul node, or MWAB-MT. In one example, the second AMF Core Network entity is the AMF Core Network entity that is serving the mobile terminal part of the wireless access backhaul node, or MWAB-MT. In one example, in a second step 1602b, the first AMF Core Network entity connects the base station part of the wireless access backhaul node to the second AMF Core Network entity. In one example, the process for connecting the base station part of the wireless access backhaul node to the second AMF Core Network entity consists in sending a RECONFIGURATION message 1202 to the second AMF Core Network entity along with a SETUP RESPONSE message 1203 to the MWAB-gNB, as discussed in Figure 12. In one example, the RECONFIGURATION message 1202 may include some information on the cause for sending the RECONFIGURATION message 1202. In another example, in a second step 1602b, the first AMF Core Network entity manages the registration of the mobile terminal part of the wireless access backhaul node to the first AMF Core Network entity. In one example, the first AMF Core Network entity may accept the connection of the MWAB-gNB by sending a SETUP RESPONSE message 1103, as discussed in Figure 11. The first AMF Core Network entity may further send a RECONFIGURATION message 1104 to the second AMF Core Network entity along with some alternate connection information, which may include at least one of an identifier of the first AMF Core Network entity, an identifier of the backhaul base station that is serving the mobile terminal part of the wireless access backhaul node, or MWAB-MT. Figure 16c is a flowchart of an example method 1600c for managing a Wireless Access Backhaul, WAB, node connectivity according to one or more embodiments of the present invention. The method 1600c of Figure 16c is performed at the AMF Core Network entity. For example, with reference to the wireless communication system shown in and described with respect to Figure 5, the AMF entity performing the method 1600c may be the AMF entity 511b. This AMF entity may be serving a BH gNB node, which may be the base station 501, while this BH gNB may be serving the MWAB-MT of a MW AB node, which may be MWAB-node 530 (which comprises MWAB-MT 531 and MWAB-gNB 532), of WAB system 500. The method 1600c as shown in and described with respect to Figure 16c may be performed by software elements and / or hardware elements. The MW AB node may be implemented in a communication device 400 as shown in and described with reference to Figure 4 with the method as shown in and described with respect to Figure 16c being performed by one or more processing units, such as the processing unit 402. Briefly, in a first step 1601c, a second AMF Core Network entity 511b receives from a first AMF Core Network entity 511a a reconfiguration request message for connecting a backhaul base station served by the second AMF Core Network entity 51 lb to the first AMF Core Network entity 511a. In one example, the reconfiguration request message is the RECONFIGURATION message 1104, as discussed in Figure 11. In one example, the reconfiguration request message includes at least one of: an identifier of the first AMF Core Network entity 51 la, an identifier of a backhaul base station. In a second step 1602c, the second AMF Core Network entity 511b may send a reconfiguration request message to the served backhaul base station to request the backhaul base station to connect to the first AMF Core Network entity 511a. In one example, the reconfiguration request message sent to the served backhaul base station is the RECONFIGURATION message 1105, as discussed in Figure 11. In one example, the reconfiguration request message includes an identifier of the first AMF Core Network entity 511a. Figure 16d is a flowchart of an example method 1600d for managing Wireless Access Backhaul, WAB, connectivity according to one or more embodiments of the present invention. The method 1600d of Figure 16d is performed at the backhaul base station, BH-gNB. For example, with reference to the wireless communication system shown in and described with respect to Figure 5, the backhaul base station performing the method 1500b may be the base station 501 of WAB system 500. The method 1600d as shown in and described with respect to Figure 16d may be performed by software elements and / or hardware elements. The BH-gNB node may be implemented in a communication device 400 as shown in and described with reference to Figure 4 with the method as shown in and described with respect to Figure 16d being performed by one or more processing units, such as the processing unit 402. Briefly, in a first step 160Id, a backhaul base station may receive, from the AMF Core Network entity it is currently connected, such as AMF entity 511b, a reconfiguration request for registering to a first AMF Core Network entity, such as AMF entity 511a. In one example, the reconfiguration request message received by the backhaul base station is the RECONFIGURATION message 1105, as discussed in Figure 11. In one example, the reconfiguration request message includes an identifier of the first AMF Core Network entity 511a. In a second step 1602d, the backhaul base station may connect to the first AMF Core Network entity 511a. Methods 1600a, 1600b, 1600c and 1600d may thus allow a MWAB-MT and its collocated MWAB-gNB to be connected to the same AMF Core Network entity, which would allow, by mutualizing the AMF software resources, a more efficient management of the mobile wireless access backhaul, MW AB, node to which the MWAB-MT and the MWAB-gNB belong. Referring now also to Figure 6 which is a schematic and simplified diagram illustrating an example message flow for use in managing network connectivity in a wireless communication system including at least one Wireless Access Backhaul, WAB, node in accordance with one or more embodiments of the invention. According to an example, the mobile terminal part 631 of a mobile Wireless Access Backhaul, WAB, node 630 (which may correspond to MW AB node 120a of Figure 1 and MW AB node 530 of Figure 5 as described above) may initiate some registration process with an AMF Core Network entity 620 by sending a REGISTRATION REQUEST message 601, which may be forwarded by the BH gNB 610 through REGISTRATION REQUEST message 602. In one aspect of the invention, the REGISTRATION REQUEST message 601 is the RRCSetupComplete message used to complete the RRC connection establishment process, as specified in 3GPP TS 38.331. In one aspect of the invention, when the REGISTRATION REQUEST message 601 is the RRCSetupComplete message 601 may embed a NAS Registration Request message included in a dedicatedNAS-Message field, as defined in 3GPP TS 38.331 and 3GPP TS 23.502. The dedicatedNAS-Message field information, which may embed some MW AB information related to the capability of the wireless access backhaul system entity, is further forwarded by the backhaul base station 610 through REGISTRATION REQUEST message 602 to the AMF 620. In one aspect of the invention, the REGISTRATION REQUEST message 602 may include some MW AB information related to the capability of the wireless access backhaul system entity. In one aspect of the invention, the REGISTRATION REQUEST message 602 is the Initial UE message, as specified in 3GPP TS 23.502. In one example, the MW AB information may include at least one of - Mobile Wireless Access Backhaul indication, or MWAB indication, information. This information indicates that the node is a MW AB node. In the embodiment shown in figure 6, this information indicates that the Mobile Termination (MT) unit 631 belongs to a Mobile Wireless Access Backhaul (MWAB) node / device; - Mobile Wireless Access Backhaul local services support, or MWAB local services support, information. This information indicates that Mobile Wireless Access Backhaul node 630, which the Mobile Termination (MT) unit 631 belongs to, supports local services and / or which local services are supported. That is to say that the MWAB node / device supports local services and / or which local services are supported. In some embodiments, this information may indicate the capability of the MWAB node 630 to perform Mobile Edge Computing (MEC) along with associated computing capacity information. In some embodiments, this information may indicate whether the MWAB node 630 comprises a UPF entity, i.e., an embedded UPF entity, such as UPF entity 533 of figure 5, for instance for the purpose of direct local inter-UE communications (e.g., direct communication of UEs 551 and 552 via UPF entity 533). - Mobile Wireless Access Backhaul co-location, or MW AB co-location, information. This information allows identifying the MWAB-gNB 632 that is co-located, or disposed, to the same Mobile Wireless Access Backhaul node 630 as the Mobile Termination (MT) unit 631. That is to say, that the co-location information may comprise information identifying the existence of the other component of the MW AB node that did not send the information, i.e., the other of the MW AB gNB or the MWAB-MT. For example, it may include an ID for the other of the MW AB gNB or the MWAB-MT. In some embodiments, the MWAB co-location information is the gNB identifier, or gNB ID, as defined in 3GPP TS 38.300. The co-location information may comprise the identifier, or ID, for both the MWAB-gNB and MWAB-MT. The co-location information may comprise information identifying the existence of both components of the MWAB node, i.e., both the MWAB-gNB and the MWAB-MT. - Femto Capability information. This information indicates if the WAB node 630 can be configured and behave as a Femto node 630. - Mobility capability information. This information indicates if the WAB node can be a mobile WAB, MWAB, node 630. - Mobility Profile information. This information indicates the mobility capability of the MWAB node 630. In some embodiments, the Mobility Profile information includes at least one of: speed information indicating a speed capability of the MWAB node (e.g., min., average or max speed), mobility range information indicating a mobility area (e.g., an area defined by some GPS coordinates) or mobility area type of the MWAB node (e.g., limited area (e.g., below 1 km2), medium area (e.g., between 1 and 10 km2) large area (e.g., greater than 10 km2)), itinerary information, which may indicate a sequence of mobility and static periods, for an itinerary the MWAB node may follow. - Mobile Wireless Access Backhaul base station capability, or MWAB-gNB capability, information. This information indicates one or more capabilities supported by the MWAB-gNB 632 that is co-located to the same Mobile Wireless Access Backhaul node 630 as the Mobile Termination (MT) unit 631. In some embodiments, the MWAB-gNB capability information may include all or some of the following information: o Load capability information. This information provides information on the load the MWAB-gNB 632 may handle when serving UEs. This information may indicate the maximum number of UEs the MWAB-gNB 632 is capable of serving, and / or a maximum throughput the MWAB-gNB is capable of handling, and / or a maximum computation power, etc. o QoS capability information. This information indicates levels of Quality of Service (QoS) the MWAB-gNB 632 is able to manage when serving UEs. In case the AMF Core Network entity 620 is not capable of managing the MWAB-MT 631 (e.g. due to a lack of WAB specific features, such as mobility management features, or because it cannot support the load associated to the wireless access backhaul node), the AMF Core Network entity 620 may send back to the backhaul base station 610 a REGISTRATION RESPONSE message 603, which may include some alternate connection information. In one example, the REGISTRATION RESPONSE message 603 is the Reroute NAS message, as specified in 3GPP TS 23.502, which may be used by the AMF 620 to reject the registration request it received in REGISTRATION REQUEST message 602. In one aspect of the invention, the alternate connection information carried by the REGISTRATION RESPONSE message 603 may include the following information: Backup WAB AMF information. This information is used to provide the requesting backhaul base station 610 with at least one alternative AMF Core Network entity, while indicating that the alternative AMF Core Network entity is capable of managing wireless access backhaul, WAB, nodes / mobile wireless access backhaul, MWAB, nodes. In one example, the Backup WAB AMF information includes at least one identifier of an AMF entity. In one example, this identifier is the AMF Name information, as defined in 3GPP TS 38.300. In one example, Backup WAB AMFinformation includes, along with an identifier of an AMF entity, an information indicating that the AMF entity identified by the identifier of an AMF entity is capable of managing wireless access backhaul, WAB, nodes / mobile wireless access backhaul, MWAB, nodes. Cause information. This information indicates the cause for sending the alternate connection information. In one example, the Cause information indicates that the AMF Core Network entity 620 sending the alternate communication information does not support WAB nodes. In one example, the Cause information indicates that the current load of the AMF Core Network entity 620 does not allow connecting an MW AB node 630. In one example, the Cause information indicates that the AMF Core Network entity 620 does not support Femto nodes. In one example, the Cause information indicates that the AMF Core Network entity 620 does not support the mobility profile of the MW AB node 630. In one example, the Cause information indicates that the AMF Core Network entity 620 does not support the QoS requirements of MW AB node 630. The backhaul base station 610 may issue to the MWAB-MT 631 a CONNECTION INFORMATION message 604, which may include some alternate connection information. In one example, the backhaul base station 610 may issue to the MWAB-MT 631 a CONNECTION INFORMATION message 604 upon reception of a REGISTRATION RESPONSE message 603. In one aspect of the invention, the CONNECTION INFORMATION message 604 is the RRCReconfiguration message, as specified in 3GPP TS 38.331. In one aspect of the invention, the alternate connection information carried by CONNECTION INFORMATION message 604 may include at least one of: Backup WAB AMF information. This information is used to provide the requesting backhaul base station 610 with at least one alternative AMF Core Network entity, while indicating that the alternative AMF Core Network entity is capable of managing wireless access backhaul, WAB, nodes / mobile wireless access backhaul, MW AB, nodes. In one example, the Backup WAB AMF information includes at least one identifier of an AMF entity. In one example, this identifier is the AMF Name information, as defined in 3GPP TS 38.300. In one example, the Backup WAB AMF information includes, along with an identifier of an AMF entity, an information indicating that the AMF entity identified by the identifier of an AMF entity is capable of managing wireless access backhaul, WAB, nodes / mobile wireless access backhaul, MW AB, nodes. Cause information. This information indicates the cause for sending the alternate connection information. In one example, the Cause information indicates that the AMF Core Network entity sending the alternate communication information the MWAB-MT tried to register with does not support WAB nodes. In one example, the Cause information indicates that the current load of the AMF Core Network entity does not allow connecting an a MW AB node. In one example, the Backup WAB AMF information carried in the CONNECTION INFORMATION 604 includes all or part of the Backup WAB AMF information received from the AMF 620 through the REGISTRATION RESPONSE message 603. In one example, the Backup WAB AMF information carried in the CONNECTION INFORMATION 604 includes the identifier of the AMF 620 to which the base station 610 has registered. In one example, the MWAB-MT 631 may share all or part of the alternate connection information it has received from the backhaul base station 610 to its collocated MWAB-gNB through an internal message 605. Referring now also to Figure 7 which is a schematic and simplified diagram illustrating an example message flow for use in managing network connectivity in a wireless communication system including at least one Wireless Access Backhaul, WAB, node in accordance with one or more embodiments of the invention. According to an example, the MWAB-gNB unit 732 of a mobile Wireless Access Backhaul, WAB, node 730 (which may correspond to MW AB node 120a of Figure 1 and MW AB node 530 of Figure 5 as described above) may initiate some connection process with an AMF Core Network entity 620 by sending a SETUP REQUEST message 701 to the AMF Core Network entity 720. In one aspect of the invention, the SETUP REQUEST message 701 may include some MW AB information related to the capability of the wireless access backhaul system entity. In one example, the MW AB information may include at least one of - Mobile Wireless Access Backhaul indication, or MWAB indication, information. This information indicates that the node is a MWAB node. In the embodiment shown in figure 7, this information indicates that the MWAB-gNB 732 belongs to a Mobile Wireless Access Backhaul (MWAB) node / Device. - Mobile Wireless Access Backhaul local services support, or MWAB local services support, information. This information indicates that the MWAB node 730, that the MWAB-gNB belongs to, supports local services and / or which local services are actually supported. In some embodiments, this information may indicate the capability of the MW AB node 730 to perform Mobile Edge Computing (MEC) along with associated computing capacity information. in some embodiments, this information may indicate whether the MW AB node 730 comprises a UPF entity, i.e., an embedded UPF entity, such as UPF entity 533 of figure 5, for instance for the purpose of direct local inter-UE communications (e.g., direct communication of UEs 551 and 552 via UPF entity 533). - Mobile Wireless Access Backhaul co-location, or MWAB co-location, information. This information allows identifying the Mobile Termination (MT) unit, MWAB-MT, 731 that is co-located to the same Mobile Wireless Access Backhaul node / device 730 as the MWAB-gNB 732. That is to say, that the co-location information may comprise information identifying the existence of the other component of the MWAB node that did not send the information, i.e. the other of the MWAB gNB or the MWAB-MT. For example, it may include an ID for the other of the MWAB gNB or the MWAB-MT. In some embodiments, the MWAB co-location information is the C-RNTI, as defined in 3GPPTS 38.300. - Femto Capability information. This information indicates if the WAB node 730 can be configured and behave as a Femto node. - Mobility capability information. This information indicates if the WAB node 730 can be a mobile WAB, MWAB, node. - Mobility Profile information. This information indicates the mobility capability of the MWAB node 730. In some embodiments, Axe. Mobility Profile information includes at least one of: speed information indicating a speed capability of the MWAB node (e.g., min., average or max speed), mobility range information indicating a mobility area (e.g., an area defined by some GPS coordinates) or mobility area type of the MWAB node (e.g., limited area (e.g., below 1 km2), medium area (e.g., between 1 and 10 km2) large area (e.g., greater than 10 km2)), itinerary information, which may indicate a sequence of mobility and static periods, for an itinerary the MWAB node may follow. - Mobile Wireless Access Backhaul base station capability, or MWAB-gNB capability, information. This information indicates one or more capabilities supported by the MWAB-gNB 732. In some embodiments, the MWAB-gNB capability information may include all or some of the following information: o Load capability information. This information provides information on the load the MWAB-gNB 732 may handle when serving UEs. This information may indicate the maximum number of UEs the MWAB-gNB 732 is capable of serving, and / or a maximum throughput the MWAB-gNB is capable of handling, and / or a maximum computation power, etc. o QoS capability information. This information indicates levels of Quality of Service (QoS) the MWAB-gNB 732 is able to manage when serving UEs. In one aspect of the invention, the SETUP REQUEST message 701 is the NG SETUP REQUEST message used to initiate an NG-RAN connection establishment process, as specified in 3GPP TS 38.413. In case the AMF Core Network entity 720 is not capable of managing the MWAB-gNB 732 (e.g., due to a lack of WAB specific features, such as mobility management features, or because it cannot support the load associated to the wireless access backhaul node), the AMF Core Network entity 720 may send back to the MWAB-gNB 732 a SETUP RESPONSE message 702, which may include some alternate connection information. In one example, the SETUP RESPONSE message 702 is the NG SETUP REQUEST message, as specified in 3GPP TS 38.413. In one example, the SETUP RESPONSE message 702 is the NG SETUP FAILURE message, as specified in 3GPP TS 38.413. In one aspect of the invention, the alternate connection information carried in the SETUP RESPONSE message 702 may include the following information: Backup WAB AMF information. This information is used to provide the requesting MWAB-gNB 732 with at least one alternative AMF Core Network entity, while indicating that the alternative AMF Core Network entity is capable of managing wireless access backhaul, WAB, nodes / mobile wireless access backhaul, MW AB, nodes. In one example, the Backup WAB AMF information includes at least one identifier of an AMF entity. In one example, this identifier is the AMF Name information, as defined in 3GPP TS 38.300. In one example, Backup WAB AMFinformation includes, along with an identifier of an AMF entity, an information indicating that the AMF entity identified by the identifier of an AMF entity is capable of managing wireless access backhaul, WAB, nodes / mobile wireless access backhaul, MW AB, nodes. Cause information. This information indicates the cause for sending the alternate connection information. In one example, the Cause information indicates that the AMF Core Network entity 720 sending the alternate communication information does not support WAB nodes. In one example, the Cause information indicates that the current load of the AMF Core Network entity 720 does not allow connecting an MW AB node 730. In one example, the Cause information indicates that the AMF Core Network entity 720 does not support Femto nodes. In one example, the Cause information indicates that the AMF Core Network entity 720 does not support the mobility profile of the MW AB node 730. In one example, the Cause information indicates that the AMF Core Network entity 720 does not support the QoS requirements of MW AB node 730. Upon reception of the SETUP RESPONSE message 702, the MWAB-gNB may initiate some connection process with an AMF Core Network entity 750, which identifier was part of the alternate connection information received in the SETUP RESPONSE message 702, by sending a SETUP REQUEST message 703 to the AMF Core Network entity 750. In one aspect of the invention, the SETUP REQUEST message 703 is the NG SETUP REQUEST message used to initiate an NG-RAN connection establishment process, as specified in 3GPP TS 38.413. Referring now also to Figure 8 which is a schematic and simplified diagram illustrating an example message flow for use in managing network connectivity in a wireless communication system including at least one Wireless Access Backhaul, WAB, node in accordance with one or more embodiments of the invention. According to an example, the backhaul base station 810 (which may correspond to backhaul base station 501 of Figure 5 as described above) may initiate some connection process with an AMF Core Network entity 820 by sending a SETUP REQUEST message 801. In one aspect of the invention, the SETUP REQUEST message 801 may include some information indicating that it was issued by a mobile Wireless Access Backhaul, MW AB, node. In one aspect of the invention, the SETUP REQUEST message 801 is the NG SETUP REQUEST message used to initiate an NG-RAN connection establishment process, as specified in 3GPP TS 38.413. In case the AMF Core Network entity 820 is not capable of managing any mobile Wireless Access Backhaul, MW AB, node, the AMF Core Network entity 820 may send back to the backhaul base station 810 a SETUP RESPONSE message 802, which may include some alternate connection information. In one example, the SETUP RESPONSE message 802 is the NG SETUP REQUEST message, as specified in 3GPP TS 38.413. In one example, the SETUP RESPONSE message 802 is the NG SETUP FAILURE message, as specified in 3GPP TS 38.413. In one aspect of the invention, the alternate connection information may include the following information: - Backup WAB AMF information. This information is used to provide the requesting backhaul base station 810 with at least one alternative AMF Core Network entity, while indicating that the alternative AMF Core Network entity is capable of managing wireless access backhaul, WAB, nodes / mobile wireless access backhaul, MW AB, nodes. In one example, the Backup WAB AMF information includes at least one identifier of an AMF entity. In one example, this identifier is the AMF Name information, as defined in 3GPP TS 38.300. In one example, \k\Q Backup WAB AMFinformation includes, along with an identifier of an AMF entity, an information indicating that the AMF entity identified by the identifier of an AMF entity is capable of managing wireless access backhaul, WAB, nodes / mobile wireless access backhaul, MW AB, nodes. Cause information. This information indicates the cause for sending the alternate connection information. In one example, the Cause information indicates that the AMF Core Network entity sending the alternate communication information does not support WAB nodes. In one example, the Cause information indicates that the current load of the AMF Core Network entity does not allow connecting an a MW AB node. Upon reception of the SETUP RESPONSE message 802, the backhaul base station 810 may initiate some connection process with an AMF Core Network entity 830, which identifier was part of the alternate connection information received in the SETUP RESPONSE message 802, by sending a SETUP REQUEST message 803 to the AMF Core Network entity 830. In one aspect of the invention, the SETUP REQUEST message 803 is the NG SETUP REQUEST message used to initiate an NG-RAN connection establishment process, as specified in 3GPP TS 38.413. Referring now also to Figure 9 which is a schematic and simplified diagram illustrating an example message flow for use in managing network connectivity in a wireless communication system including at least one Wireless Access Backhaul, WAB, node in accordance with one or more embodiments of the invention. According to an example, the backhaul base station 920 (which may correspond to backhaul base station 501 of Figure 5 as described above) may broadcast a NETWORK INFORMATION message 901, which includes some connection information to all the MWAB-MT entities in the vicinity. In one example, the NETWORK INFORMATION message 901 is the SIB1 message, as defined in 3GPP TS 38.331. The broadcasted connection information includes at least one of: WAB capable AMF information. This information is used to provide MWAB-MT entity that would receive the connection information with at least one AMF Core Network entity which is capable of managing wireless access backhaul, WAB, nodes / mobile wireless access backhaul, MW AB, nodes. In one example, the WAB capable AMF information includes at least one identifier of an AMF entity. In one example, this identifier is the AMF Name information, as defined in 3GPPTS 38.300. In one example, the WAB capable AMFinformation includes, along with an identifier of an AMF entity, an information indicating that the AMF entity identified by the identifier of an AMF entity is capable of managing wireless access backhaul, WAB, nodes / mobile wireless access backhaul, MW AB, nodes. In one example, the MWAB-MT 931 may share the WAB capable AMF information it has received from the backhaul base station 920 to its collocated MWAB-gNB through an internal message 902. Referring now also to Figure 10 which is a schematic and simplified diagram illustrating an example message flow for use in managing network connectivity in a wireless communication system including at least one Wireless Access Backhaul, WAB, node in accordance with one or more embodiments of the invention. According to an example, the MWAB-gNB 1032 may connect with the AMF Core Network entity 1020 by sending a SETUP REQUEST message 1001, used to request connection, and receiving a SETUP RESPONSE message 1002, used to indicate that the connection request was accepted by the AMF Core Network entity 1020. In one aspect of the invention, the SETUP REQUEST message 1001 is the NG SETUP REQUEST message, as specified in 3GPP TS 38.413. In one example, the SETUP RESPONSE message 1002 is the NG SETUP REQUEST message, as specified in 3GPP TS 38.413. Then, the MWAB-gNB may request its collocated MWAB-MT entity 1031 to send a NETWORK INFORMATION message 1004 to its serving backhaul base station 1010, which may include some alternate connection information. In one example, the NETWORK INFORMATION message 1004 is the UEInformationResponse message, as specified in 3GPP TS 38.331. In one example, the NETWORK INFORMATION message 1004 is an RRC message, as specified in 3GPP TS 38.331. The alternate connection information includes at least one of: - MWAB-gNB AMF information. This information is used to provide the backhaul base station entity 1010 with the identifier of the AMF Core Network entity 1020 which is managing MWAB-gNB 1032. In one example, this identifier is the AMF Name information, as defined in 3GPP TS 38.300. Upon reception of the NETWORK INFORMATION message 1004, the backhaul base station entity 1010 may decide to connect to the same AMF entity 1020 as the MWAB-gNB 1032. To do so, the backhaul base station entity 1010 may send a RECONFIGURATION message 1005 to its BH AMF 1040, which includes some alternate connection information information. In one example, the RECONFIGURATION message 1005 is the RAN CONFIGURATION UPDATE message, as defined in TS 38.413. The alternate connection information includes at least one of: WAB AMF Reconfiguration Request information. This information is used to indicate to the receiving AMF entity 1040 that the backhaul base station 1010 is requesting to register to a new AMF entity supporting WAB features. - New WAB AMF information. This information is used to provide the receiving AMF entity 1040 with the identifier of the new AMF entity 1020 the backhaul base station is to register. In one example, this identifier is the AMF Name information, as defined in 3GPPTS 38.300. The AMF 1040 may respond to the RECONFIGURATION message 1005 by sending back to the backhaul base station 1010 a RECONFIGURATION ACKNOWLEDGE message 1006, which may include some alternate connection acknowledge information. In one example, the RECONFIGURATION ACKNOWLEDGE message 1006 is the RAN CONFIGURATION UPDATE ACKNOWLEDGE message, as defined in TS 38.413. The alternate connection acknowledge information includes at least one of WAB AMF Reconfiguration acknowledge information. This information is used to indicate to the receiving backhaul base station 1010 that its former WAB AMF Reconfiguration Request sent in the RECONFIGURATION message 1005 has been accepted or rejected by the AMF entity 1040. New WAB AMF information. This information is used to indicate the identifier of the new AMF entity 1020 the backhaul base station is allowed to register. In one example, this identifier is the AMFName information, as defined in 3GPP TS 38.300. Upon reception of the RECONFIGURATION ACKNOWLEDGE message 1006, the backhaul base station 1010 may initiate a connection process by sending a SETUP REQUEST message 1007 to the AMF 1020. In one example, the SETUP REQUEST message 1007 is the NG SETUP REQUEST message, as specified in 3GPP TS 38.413. Referring now also to Figure 11 which is a schematic and simplified diagram illustrating an example message flow for use in managing network connectivity in a wireless communication system including at least one Wireless Access Backhaul, WAB, node in accordance with one or more embodiments of the invention. According to an example, the MWAB-gNB 1132 may connect to the AMF Core Network entity 1120 by sending a SETUP REQUEST message 1102, used to request connection, and receiving a SETUP RESPONSE message 1103, used to indicate that the connection request was accepted by the AMF Core Network entity 1020. In one aspect of the invention, the SETUP REQUEST message 1102 is the NG SETUP REQUEST message, as specified in 3GPP TS 38.413. In one example, the SETUP RESPONSE message 1103 is the NG SETUP REQUEST message, as specified in 3GPP TS 38.413. In one example, the SETUP REQUEST message 1102 may include some alternate connection information, which may include at least one of: - MWAB-MT AMF information. This information is used to provide the AMF entity 1120 with the identifier of the AMF entity 1140 that is managing the WAB-MT 1131. In one example, this identifier is tW AMF Name information, as defined in 3GPP TS 38.300. BH-gNB Identifier information. This information is used to provide the AMF entity 1120 with the identifier of the backhaul base station 1110 that is serving the MWAB-MT 1131. The AMF entity 1120 may further request the AMF 1140 to reconfigure the backhaul base station 1110 by sending a RECONFIGURATION message 1104, which may include some alternate connection information. In one example, the RECONFIGURATION message 1104 is the Namf Communication^NIMessageNotijy message, as specified in 3GPP TS 23.502. In one example, the alternate connection information in RECONFIGURATION message 1104 may include at least one of: - MWAB-gNB AMF information. This information is used to provide the AMF entity 1140 with the identifier of the AMF entity 1120 that is connected to the MWAB-gNB 1132. In one example, this identifier is the AMF Name information, as defined in 3GPP TS 38.300. BH-gNB Identifier information. This information is used to provide the AMF entity 1140 with the identifier of the backhaul base station 1110 that is serving the MWAB-MT 1131. Upon reception of the RECONFIGURATION message 1104, the AMF 1140 may perform the reconfiguration of the backhaul base station 1110 by sending a RECONFIGURATION message 1105, which may include some alternate connection information. In one example, the RECONFIGURATION message 1105 is the AMF CONFIGURATION UPDATE message, as specified in 3GPP TS 38.413. In one example, the RECONFIGURATION message 1105 is the AMF STATUS INDICA TION message, as specified in 3GPP TS 38.413. In one example, the alternate connection information carried by RECONFIGURATION message 1105 may include at least one of: - MWAB-gNB AMF information. This information is used to provide the backhaul base station 1110 with the identifier of the AMF entity 1120 that is connected to the WAB-gNB 1132. In one example, this identifier is the AMFName information, as defined in 3GPPTS 38.300. Upon reception of the RECONFIGURATION message 1105, the backhaul base station 1110 may initiate a connection process by sending a SETUP REQUEST message 1106 to the AMF 1120. In one example, the SETUP REQUEST message 1106 is the NG SETUP REQUEST message, as specified in 3GPP TS 38.413. Referring now also to Figure 12 which is a schematic and simplified diagram illustrating an example message flow for use in managing network connectivity in a wireless communication system including at least one Wireless Access Backhaul, WAB, node in accordance with one or more embodiments of the invention. According to an example, the MWAB-gNB 1232 may register with the AMF Core Network entity 1220 by sending a SETUP REQUEST message 1201, which may include some alternate connection information. In one aspect of the invention, the SETUP REQUEST message 1201 is the NG SETUP REQUEST message, as specified in 3GPP TS 38.413. The alternate connection information includes at least one of: - MWAB-MT AMF information. This information is used to provide the backhaul base station entity 1210 with the identifier of the AMF Core Network entity 1240 which is managing MWAB-MT 1231. In one example, this identifier is the AMF Name information, as defined in 3GPP TS 38.300. Upon reception of the SETUP REQUEST message 1201, the AMF 1220 may initiate a connection by sending a RECONFIGURATION message 1202 to the AMF 1240 and a SETUP RESPONSE message 1203 to the MWAB-gNB 1232. In one example, the RECONFIGURATION message 1202 is the Namf Communication^NIMessageNotiJy message, as specified in 3GPP TS 23.502. In one example, the SETUP RESPONSE message 1203 is the Reroute NAS message, as specified in 3GPP TS 23.502. 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 similar 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. 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. 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. 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. 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 5 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, 10 signals, or other transient media, but are instead directed to non-transient, 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. 15

Claims

1. A method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at an access and mobility management function, AMF, entity of the at least one core network comprising:receiving a request for managing connectivity of at least one of: the gNB component, the MT component, and a backhaul gNB associated with the WAB node;accepting or rejecting the request for managing connectivity, based on received information associated with the WAB node;sending a response indicating the AMF entity has accepted or rejected the request for managing connectivity.

2. The method of claim 1, wherein the received information includes at least one of:information indicating the WAB node is a mobile WAB node;information indicating the WAB node supports local services;information identifying a gNB component of the WAB node co-located with a mobile termination component of the WAB node; andcontext information associated with the WAB node.

3. The method of claim 1 or 2, wherein, in a case of accepting the request for managing connectivity, the response includes an identification field, and wherein the value of the identification field identifies the AMF entity that has accepted the request.

4. The method of claim 1 or 2, wherein, in a case of rejecting the request for managing connectivity, the response includes a cause field, and wherein the value of the cause field indicates a cause of the rejection.

5. The method of claim 4, wherein the value of the cause field is selected from a set of predefined values including a value to indicate that the AMF entity does not support mobile WAB nodes.

6. The method of claim 4 or 5, wherein the response further includes an AMF backup field, and wherein the value of the AMF backup field identifies another AMF entity that supports mobile WAB nodes.

7. The method of any preceding claim, wherein receiving a request for managing connectivity comprises receiving a request, from a backhaul gNB associated with the WAB node, for managing connectivity of the gNB component or the MT component.

8. The method of any one of claims 1 to 6, wherein receiving a request for managing connectivity comprises receiving a request, from the mobile WAB node, for managing connectivity of the gNB component or the MT component.

9. The method of any preceding claim, wherein sending a response comprises sending a response to the WAB node.

10. The method of any one of claims 1 to 8, wherein sending a response comprises sending a response to the backhaul gNB.

11. The method of any one of claims 1 to 8, wherein sending a response comprises sending a response to another AMF entity supporting mobile WAB nodes.

12. The method of any one of claims 1 to 6, wherein receiving a request for managing connectivity comprises receiving a request, from a backhaul gNB associated with the WAB node, for managing connectivity of the backhaul gNB associated with the WAB node, and wherein sending a response comprises sending a response to the backhaul gNB.

13. A method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at the backhaul gNB comprising:receiving, from a first access and mobility management function, AMF, entity of the at least one core network, information associated to a second AMF entity; andsending, to the WAB node, the information associated to the second AMF entity.

14. The method of claim 13, wherein the second AMF is capable of serving the WAB node.

15. The method of claim 13 or 14, wherein the information associated to the second AMF entity includes at least one of: an identifier of the second AMF entity, and a cause for sending the information.

16. The method of any one of claims 13 to 15, further comprising the step of: performing a connection procedure with the second AMF entity.

17. The method of any one of claims 13 to 16, wherein the step of sending, to the WAB node, the information associated to the second AMF entity comprises forwarding the information to the MT component of the WAB node.

18. The method of claim 17, wherein the step of forwarding the information to the MT component of the WAB node comprises forwarding the information through a connection information message.

19. The method of any one of claims 13 to 16, wherein the step of sending, to the WAB node, the information associated to the second AMF entity comprises broadcasting the information the MT components of all mobile WAB nodes in the vicinity of the backhaul gNB.

20. A method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at the WAB node comprising:sending, by the gNB component, connection information to a base station connected to a first access and mobility management function, AMF, entity of the at least one core network, wherein said connection information is associated to a second AMF entity capable of serving the WAB node.

21. The method of claim 20, wherein the step of sending the connection information comprises sending, by the gNB, the connection information to the MT component, and forwarding, by the MT component, the connection information to the base station.

22. The method of claim 21, wherein the connection information is forwarded by the MT component via a network information message.

23. A method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at the backhaul gNB comprising:receiving, from the MT component, information associated to a second access and mobility management function, AMF, entity of the at least one core network; andsending, to a first AMF entity to which the backhaul gNB is already connected, the information associated to the second AMF entity.

24. The method of claim 23, wherein the step of sending, to a first AMF entity to which the backhaul gNB is already connected, the information associated to the second AMF entity comprises sending a reconfiguration message to the first AMF entity.

25. The method of claim 23 or 24, wherein the information associated to the second AMF entity includes an identifier of the second AMF entity.26 The method of any one of claims 23 to 25, further comprising the step of: performing a connection procedure with the second AMF entity.

27. A method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at the WAB node comprising:sending, to a first access and mobility management function, AMF, entity of the at least one core network, connection information, wherein said connection information is associated to a second AMF entity capable of serving the WAB node.

28. The method of claim 27, wherein the step of sending connection information is performed by the gNB component.

29. The method of claim 28, wherein the information is received by the gNB component from the MT component prior to sending.

30. The method of any one of claims 27 to 29, wherein the MT component is connected to the second AMF entity.

31. The method of any one of claims 27 to 30, wherein the connection information includes at least one of: an identifier of the second AMF entity, and an identifier of the backhaul gNB.

32. A method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at a first access and mobility management function, AMF, entity of the at least one core network comprising:receiving, from the gNB component, connection information, wherein said connection information is associated to a second AMF entity capable of serving the MT component.

33. The method of claim 32, wherein the connection information includes at least one of: an identifier of the second AMF entity, and an identifier of the backhaul gNB.

34. The method of claim 32 or 33, further comprising the step of:sending, to the second AMF entity, at least one of: an identifier of the first AMF entity, and an identifier of the backhaul gNB.

35. The method of any one of claims 32 to 34, further comprising the step of: performing a connection procedure with the second AMF entity, in which the gNB component is connected to the second AMF entity.

36. The method of any one of claims 32 to 34, further comprising the step of: performing a connection procedure, in which the MT component is connected to the first AMF entity.

37. A method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at a first access and mobility management function, AMF, entity of the at least one core network comprising:receiving, from a second AMF entity, information for connecting a backhaul base station served by the second AMF entity to the first AMF entity.

38. The method of claim 37, wherein the information includes at least one of: an identifier of the second AMF entity, and an identifier of the backhaul base station served by the second AMF entity.

39. The method of claim 37 or 38, further comprising the step of:sending, to the backhaul base station served by the second AMF entity, a reconfiguration request message.

40. The method of claim 39, wherein the reconfiguration request message includes an identifier of the first AMF entity.

41. A method for use in managing connectivity of a wireless access backhaul, WAB, node, said WAB node including a mobile termination, MT, component and a gNB component, the WAB node being connectable to at least one core network via a backhaul gNB, the method at the backhaul gNB comprising:receiving, from a first access and mobility management function, AMF, entity of the at least one core network to which the backhaul gNB is currently connected, information for connecting the backhaul gNB to a second AMF entity.

42. The method of claim 41, wherein the information includes an identifier of the second AMF entity.

43. The method of claim 41 or 42, further comprising the step of:performing a connection procedure to connect the backhaul gNB to the second AMF entity.

44. The method according to any preceding claim, wherein the WAB node is a mobile wireless access backhaul, MW AB, node.

45. 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 44.

46. A computer-readable medium carrying a computer program according to claim 45.

47. 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 13 to 19, 23 to 26 and 41 to 44, and claim 45 when dependent on any one of claims 13 to 19, 23 to 26 and 41 to 44.

48. 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 20 to 22 and 27 to 31, and claim 45 when dependent on any one of claims 20 to 22 and 27 to 31.

49. An apparatus for an 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 12 and 32 to 40, and claim 45 when dependent on any one of claims 1 to 12 and 32 to 40.

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