CN117751682A - Method and apparatus for moving from one geographical area to another geographical area in a communication system including a non-terrestrial network portion - Google Patents

Abstract

A communication system is disclosed that includes a non-terrestrial network portion comprising a plurality of cells, each cell serving at least one coverage area. The first base station stores a User Equipment (UE) context associated with suspending a Radio Resource Control (RRC) connection with a first coverage area of the UE. The UE initiates a procedure for resuming the suspended RRC connection via a second cell serving a coverage area different from the first coverage area, transmits information related to a location of the UE, and receives a message for releasing the RRC connection based on the location of the UE from a base station controlling the second cell.

Description

Method and apparatus for moving from one geographical area to another geographical area in a communication system including a non-terrestrial network portion

Technical Field

The present disclosure relates to communication systems.

Background

The present invention relates to wireless communication systems and devices thereof operating in accordance with the third generation partnership project (3 GPP) standard or equivalents or derivatives thereof. The present disclosure relates particularly, but not exclusively, to improvements relating to UE context retrieval/UE redirection in so-called "5G" (or "next generation") systems employing non-terrestrial portions including on-board or on-board network nodes.

Under the 3GPP standard, a NodeB (or "eNB" in LTE, "gNB" in 5G) is a base station via which a communication device (user equipment or "UE") connects to a core network and communicates with other communication devices or remote servers. The communication device may be, for example, a mobile communication device such as a mobile phone, smart watch, personal digital assistant, laptop/tablet computer, web browser, e-book reader, and/or the like. Such mobile (or even generally stationary) devices are typically operated by users (and thus they are often collectively referred to as user equipment "UEs"), although IoT devices and similar MTC devices may also be connected to the network. For simplicity, the term base station will be used herein to refer to any such base station, and the term mobile device or UE will be used to refer to any such communication device.

A recent development of the 3GPP standard is the so-called "5G" or "new air interface" (NR) standard, which refers to an evolving communication technology intended to support various applications and services, such as Machine Type Communication (MTC), internet of things (IoT)/industrial internet of things (IIoT) communication, vehicle communication and autonomous vehicles, high resolution video streaming, smart city services, and/or the like. The 3GPP intends to support 5G through so-called 3GPP next generation (NextGen) Radio Access Networks (RANs) and 3GPP NextGen core (NGC) networks. Various details of 5G networks are described, for example, in the Next Generation Mobile Network (NGMN) alliance, "NGMN 5G White Paper" V1.0, which is available from https:// www.ngmn.org/5G-White-Paper.

End user communication devices are commonly referred to as User Equipment (UE), which may be operated by humans or include automatic (MTC/IoT) devices. While base stations of 5G/NR communication systems are commonly referred to as new air interface base stations ("NR-BS") or "gnbs," it will be appreciated that they may be referred to using the term "eNB" (or 5G/NR eNB) more typically associated with Long Term Evolution (LTE) base stations (also commonly referred to as "4G" base stations). The 3GPP Technical Specifications (TS) 38.300V16.4.0 and TS 37.340V16.4.0 define the following nodes, etc:

gNB: a node towards an NR user plane and control plane protocol terminal of the UE is provided and connected to a 5G core network (5 GC) via an NG interface.

ng-eNB: an evolved universal terrestrial radio access (E-UTRA) user plane and control plane protocol terminal towards a UE is provided and is connected to a node of a 5GC via an NG interface.

En-gNB: a node is provided towards the NR user and control plane protocol terminals of the UE and acts as an auxiliary node in an E-UTRA-NR dual connectivity (EN-DC).

NG-RAN node: gNB or ng-eNB.

The 3GPP is also working to specify integrated satellite and terrestrial network infrastructure in the context of 5G. The term non-terrestrial network (NTN) refers to a network or network segment that is being transmitted using an on-board or satellite-borne vehicle. Satellites refer to satellite vehicles in geostationary orbit (GEO) or non-geostationary orbit (ngao), such as Low Earth Orbit (LEO), medium Earth Orbit (MEO), and High Elliptical Orbit (HEO). An airborne vehicle refers to an aerial platform (HAP) containing an unmanned aerial vehicle system (UAS) that includes tethered UASs that are lighter and heavier than an airborne UAS, all operating quasi-steady at a height typically between 8 and 50 km.

The 3GPP Technical Report (TR) 38.811V15.4.0 is a study of new air interfaces to support such non-terrestrial networks. The study includes NTN deployment scenarios and related system parameters (such as architecture, altitude, orbit, etc.) and descriptions of the adaptation of the 3GPP channel model to non-terrestrial networks (propagation conditions, mobility, etc.), among others. 3GPP TR 38.821V16.0.0 provides further details regarding NTN.

It is expected that non-terrestrial networks will:

-helping to facilitate push out of 5G service in out of service or under service areas to improve the performance of the ground network;

enhancing service reliability by providing service continuity for user equipment or for mobile platforms (e.g. passenger vehicles-aircraft, ships, high speed trains, buses);

-improving service availability from place to place; especially for critical communications, future rail/marine/aviation communications; and

enabling 5G network scalability by providing efficient multicast/broadcast resources for data delivery towards the network edge or even directly to user equipments.

NTN access is typically characterized by the following elements (among others):

NTN terminal: it may refer to a 3GPP UE or a satellite system specific terminal in case the satellite does not directly serve the 3GPP UE.

Service link, which refers to a radio link between user equipment and space/airborne platform (which may be in addition to the radio link of the ground-based RAN).

-space or airborne platforms.

-a gateway ("NTN gateway") connecting the satellite or air access network to the core network. It will be appreciated that the gateway will most likely be co-located with the base station.

-feeder link, which refers to a radio link between gateway and space/airborne platform.

A satellite or aircraft may generate several beams over a given area to provide corresponding NTN cells. These beams have a typical elliptical footprint on the earth's surface.

The 3GPP intends to support three types of NTN beams or cells:

-an earth fixed cell, characterized in that the beam(s) always cover the same geographical area (e.g. GEO satellites and HAPS);

-quasi-earth fixed cells characterized in that the beam(s) cover one geographical area for a limited period of time and a different geographical area during another period of time (e.g. NGEO satellites generating steerable beams); and

-earth moving cells, characterized in that the beam(s) cover one geographical area at one instant and a different geographical area at another instant (e.g. NGEO satellites generating fixed or non-steered beams).

The beam footprint is fixed on earth, with the satellite or aircraft remaining fixed in elevation/azimuth relative to a given earth point (e.g., GEO and UAS).

As the satellite circulates around the earth (e.g., LEO) or on an elliptical orbit around the earth (e.g., HEO), the beam footprint may move over the earth as the satellite or the aircraft moves in its orbit. Alternatively, the beam coverage area may be temporally earth fixed (or quasi-earth fixed), wherein in such case appropriate beam pointing mechanisms (mechanical or electronic steering) may be used to compensate for satellite or aircraft motion.

LEO satellites may have steerable beams, where in this case the beams are temporarily directed at a substantially fixed coverage area on the earth. In other words, the beam coverage areas (which represent NTN cells) are fixed on the ground for a certain amount of time before they change their area of interest to another NTN cell (due to the movement of the satellite in its orbit). From a cell coverage/UE perspective, this results in cell changes occurring periodically at discrete intervals, since even in cases where these beams serve the same terrestrial area (with the same coverage area), different Physical Cell Identities (PCIs) and/or synchronization signal/Physical Broadcast Channel (PBCH) blocks (SSBs) must be assigned after each serving link change. As LEO satellites without steerable beams move along their orbits, these satellites cause the beams (cells) to move continuously in a scanning motion over the ground, and as in the case of steerable beams, service link changes occur periodically at discrete intervals, and thus cell changes occur periodically at discrete intervals.

Similar to the service link change, the feeder link change also occurs at regular intervals due to the movement of the satellite in its orbit. Both the serving link change and the feeder link change may be made between different base stations/gateways (which may be referred to as "inter-gcb radio link handovers") or within the same base station/gateway ("intra-gcb radio link handovers").

Disclosure of Invention

Technical problem

The 3GPP is still making detailed specifications, however, assuming that an earth-fixed tracking area will be used with earth-fixed and/or mobile cells.

The cell groups are assigned to different coverage areas or service/tracking areas, which may correspond to respective geographic areas (such as countries, cities, regions, or any similar geographic units). Each cell has an associated "NR cell global identifier" (NCGI) that is made up of a Public Land Mobile Network (PLMN) identity (PLMN ID) to which the cell belongs and an NR Cell Identity (NCI) of the cell. The "global gNB ID" is used to globally identify the gNB, and is composed of a PLMN identification to which the gNB belongs and a gNB ID (which is an identifier for identifying a specific gNB within the PLMN). However, it is not excluded that cells served by the gNB do not broadcast the associated PLMN IDs included in the global gNB ID.

A base station (gNB/NG-RAN node) may control cells in different geographic areas (e.g., different coverage areas, service areas, tracking areas, or countries), or may serve more than one of such geographic areas due to coverage area overflow across the boundary between adjacent areas (when a portion of a cell covering a boundary region in one area extends to an adjacent area). If the base station serves more than one geographical area, the base station ensures (by taking into account the UE location information (if available)) that each UE is using an access and mobility management function (AMF) for serving the geographical area in which the UE is located.

The UE may initially establish a Radio Resource Control (RRC) connection via the cell and register with the AMF in one geographic area (e.g., in a first country). Subsequently, the UE, after being in an RRC inactive state, may attempt to restore the RRC connection in cells belonging to different base stations serving different geographical areas (e.g., in a second country). This may occur, for example, when the UE moves across boundaries or when a change in signal conditions causes the UE to select a new cell in another country/region.

The cell (in the new region/country) for which the UE attempts to resume RRC connection may not broadcast the previous PLMN ID, although the cell may still provide connectivity to the AMF of the PLMN. However, when the UE resumes the RRC connection in the new area or country, the earlier UE context is not suitable for the region and cannot be used in the new cell (even if the new base station can restore the UE context from the old base station of the UE based on the information from the UE). This will result in failure to retrieve or use the UE context and thus the RRC connection cannot be restored at the base station.

Accordingly, the present invention seeks to provide a method and associated apparatus for solving or at least alleviating (at least some of) the problems described above.

Although the present invention will be described in detail in the context of a 3GPP system (5G network including NTN) for efficiency of understanding by those skilled in the art, the principles of the present invention may also be applied to other systems.

Solution for solving the problem

In one aspect, the present invention provides a method by a user equipment, UE, configured to communicate via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a first base station associated with a first coverage area stores UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, of the UE, the method comprising: initiating a procedure for resuming the suspended RRC connection via a cell serving a coverage area different from the first coverage area, and transmitting information related to a location of the UE; and receiving a message to release the RRC connection based on the location of the UE from a base station controlling a cell serving the different coverage area.

In one aspect, the present invention provides a method by a user equipment, UE, configured to communicate via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein the UE has a UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, with respect to a first coverage area, the method comprising: determining that the current location of the UE is in a coverage area different from the first coverage area; and releasing the RRC connection based on the current location of the UE.

In one aspect, the present invention provides a method performed by a network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a base station associated with a first coverage area stores UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, of the UE, the method comprising: receiving a message from the UE initiating a procedure for resuming the suspension of the RRC connection via a cell serving a coverage area different from the first coverage area, and receiving information related to a location of the UE; and transmitting a message to the UE to release the RRC connection based on the location of the UE.

In one aspect, the present invention provides a method performed by a network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein the network node stores UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, of the UE in relation to a first coverage area, the method comprising: receiving information related to a location of the UE from a base station serving a second coverage area via a cell; and transmitting a response to the base station for releasing the RRC connection when the first coverage area and the second coverage area are different.

In one aspect, the present invention provides a method by an access and mobility management function, AMF, configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a first base station stores UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, of the UE in relation to the first coverage area, the method comprising: receiving information related to a location of the UE from a base station serving a second coverage area via a cell; and transmitting a response for releasing the RRC connection to a base station serving the second coverage area when the first coverage area and the second coverage area are different.

In one aspect, the present invention provides a user equipment, UE, configured to communicate via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a first base station associated with a first coverage area stores a UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, of the UE, the UE comprising: means for initiating a procedure for resuming the suspended RRC connection via a cell serving a coverage area different from the first coverage area, and for transmitting information related to a location of the UE; and means for receiving a message to release the RRC connection based on the location of the UE from a base station controlling a cell serving the different coverage area.

In one aspect, the present invention provides a user equipment, UE, configured to communicate via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein the UE has a UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, with respect to a first coverage area, the UE comprising: means for determining that a current location of the UE is in a different coverage area than the first coverage area; and means for releasing the RRC connection based on the current location of the UE.

In one aspect, the present invention provides a network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a base station associated with a first coverage area stores UE context associated with a suspension of a radio resource control connection, i.e. suspension of an RRC connection, of the UE, the network node comprising: means for receiving a message from the UE initiating a procedure for resuming the suspension of RRC connection via a cell serving a coverage area different from the first coverage area, and for receiving information related to a location of the UE; and means for transmitting a message to the UE to release the RRC connection based on the location of the UE.

In one aspect, the present invention provides a network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein the network node stores UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, of the UE in relation to a first coverage area, the network node comprising: means for receiving information related to a location of the UE from a base station serving a second coverage area via a cell; and transmitting a response to the base station to release the RRC connection when the first coverage area and the second coverage area are different.

In one aspect, the present invention provides an access and mobility management function, AMF, configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a first base station stores UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, of the UE, the AMF comprising: means for receiving information related to a location of the UE from a base station serving a second coverage area via a cell; and transmitting a response for releasing the RRC connection to a base station serving the second coverage area when the first coverage area and the second coverage area are different.

In another aspect, the present invention provides a user equipment, UE, configured to communicate via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a first base station associated with a first coverage area stores a UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, of the UE, the UE comprising: a processor; a transceiver; and a memory storing instructions, wherein the controller is configured to: initiating a procedure for resuming the suspended RRC connection via a cell serving a coverage area different from the first coverage area, and transmitting information related to a location of the UE; and controlling the transceiver to receive a message to release the RRC connection based on the location of the UE from a base station controlling a cell serving the different coverage area.

In another aspect, the present invention provides a user equipment, UE, configured to communicate via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein the UE has a UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, with respect to a first coverage area, the UE comprising: a processor; a transceiver; and a memory storing instructions, wherein the controller is configured to: determining that the current location of the UE is in a coverage area different from the first coverage area; and releasing the RRC connection based on the current location of the UE.

In another aspect, the present invention provides a network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a base station associated with a first coverage area stores UE context associated with a suspension of a radio resource control connection, i.e. a suspension of an RRC connection, of the UE, the network node comprising: a processor; a transceiver; and a memory storing instructions, wherein the controller is configured to control the transceiver to: receiving a message from the UE initiating a procedure for resuming the suspension of the RRC connection via a cell serving a coverage area different from the first coverage area, and receiving information related to a location of the UE; and transmitting a message to the UE to release the RRC connection based on the location of the UE.

In another aspect, the present invention provides a network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein the network node stores UE context associated with a suspended radio resource control, RRC, connection of the UE in relation to a first coverage area, the network node comprising: a processor; a transceiver; and a memory storing instructions, wherein the controller is configured to control the transceiver to: receiving information related to a location of the UE from a base station serving a second coverage area via a cell; and transmitting a response to the base station for releasing the RRC connection when the first coverage area and the second coverage area are different.

In another aspect, the present invention provides an access and mobility management function, AMF, configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a first base station stores UE context associated with a suspended radio resource control connection, i.e. suspended RRC connection, of the UE in relation to the first coverage area, the AMF comprising: a processor; a transceiver; and a memory storing instructions, wherein the controller is configured to control the transceiver to: receiving information related to a location of the UE from a base station serving a second coverage area via a cell; and transmitting a response to release the RRC connection to the second base station when the first coverage area and the second coverage area are different.

Aspects of the invention extend to corresponding systems, apparatus, and computer program products, such as computer-readable storage media, having instructions stored thereon, operable to program a programmable processor to perform a method as set forth above or described in the aspects and possibilities recited in the claims, and/or to program a suitably adapted computer to provide an apparatus as recited in any one of the claims.

Each feature disclosed in this specification (which term includes the claims) and/or shown in the drawings may be incorporated in the present invention independently of (or in combination with) any other disclosed and/or illustrated feature. In particular, but not by way of limitation, features of any claim dependent on a particular independent claim may be introduced into that independent claim in any combination or separately.

Drawings

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

fig. 1 schematically shows a mobile (cellular or wireless) telecommunication system to which embodiments of the invention may be applied;

FIG. 2 is a schematic block diagram of a mobile device forming part of the system shown in FIG. 1;

FIG. 3 is a schematic block diagram of an NTN node (e.g., satellite/UAS platform) forming part of the system shown in FIG. 1;

fig. 4 is a schematic block diagram of an access network node (e.g., base station) forming part of the system shown in fig. 1;

FIG. 5 schematically illustrates two exemplary scenarios to which embodiments of the present invention may be applied;

FIG. 6 schematically illustrates two exemplary scenarios to which embodiments of the present invention may be applied;

Fig. 7 is a signaling (timing) diagram illustrating some exemplary ways in which UE context retrieval may be performed, according to an embodiment of the present invention;

fig. 8 is a signaling (timing) diagram illustrating some exemplary ways in which UE context retrieval may be performed, according to an embodiment of the present invention;

fig. 9 is a signaling (timing) diagram illustrating some exemplary ways in which UE context retrieval may be performed, according to an embodiment of the present invention;

fig. 10 is a signaling (timing) diagram illustrating some exemplary ways in which UE context retrieval may be performed, according to an embodiment of the present invention; and

fig. 11 schematically illustrates some exemplary architectural options for providing NTN features in the system illustrated in fig. 1.

Detailed Description

SUMMARY

Fig. 1 schematically shows a mobile (cellular or wireless) telecommunication system 1 to which embodiments of the invention may be applied.

In this system 1, users of mobile devices 3 (UEs) may communicate with each other and with other users via access network nodes (respective satellites 5 and/or base stations 6 and data networks 7) using appropriate 3GPP Radio Access Technologies (RATs), e.g. E-UTRA and/or 5G RATs. As will be appreciated by those skilled in the art, although three mobile devices 3, one satellite 5 and one base station 6 are shown in fig. 1 for illustrative purposes, the system will typically include other satellite/UAS platforms, base station/RAN nodes and mobile devices (UEs) when implemented.

It will be appreciated that a plurality of base stations 6 form a (radio) access network or (R) AN and a plurality of NTN nodes 5 (satellite and/or UAS platforms) form a non-terrestrial network (NTN). Each NTN node 5 is connected to an appropriate gateway (in this case co-located with the base station 6) using a so-called feeder link and to the respective UE 3 via a respective service link. Thus, the mobile device 3, when served by the NTN node 5, communicates data to and from the base station 6 via the NTN node 5 using the appropriate serving link (between the mobile device 3 and the NTN node 5) and the feeder link (between the NTN node 5 and the gateway/base station 6). In other words, the NTN forms part of the (R) AN, although the NTN may also provide satellite communication services independently of E-UTRA and/or 5G communication services.

Although not shown in fig. 1, the neighboring base stations 6 are connected to each other via an appropriate base station-to-base station interface (such as a so-called "X2" interface, "Xn" interface, and/or the like). The base station 6 is also connected to the data network node via a suitable interface, such as a so-called "S1", "NG-C", "NG-U" interface and/or the like.

The data network (or core network) 7 (e.g. EPC in case of LTE or NGC in case of NR/5G) typically comprises logical nodes (or "functions") for supporting communication in the telecommunication system 1 as well as for subscriber management, mobility management, charging, security, call/session management (and others). For example, the data network 7 of the "next generation"/5G system will include user plane entities and control plane entities such as one or more Control Plane Functions (CPFs) and one or more User Plane Functions (UPFs) and the like. The so-called access and mobility management function (AMF) is responsible for handling the connection and mobility management tasks for the mobile device 3. The data network 7 is also coupled to other data networks such as the internet or a similar Internet Protocol (IP) based network (not shown in fig. 1).

Each NTN node 5 controls a plurality of directional beams via which an associated NTN cell may be provided. Specifically, each beam has an associated coverage area on the earth's surface corresponding to an NTN cell. Each NTN cell (beam) has an associated Physical Cell Identity (PCI) and/or beam identity. While NTN node 5 is traveling along its trajectory, the beam coverage area may be moving. Alternatively, the beam coverage area may be earth fixed, in which case appropriate beam pointing mechanisms (mechanical or electronic steering) may be used to compensate for the movement of the NTN node 5.

Each cell has an associated "NR cell global identifier" (NCGI) to globally identify the cell. The NCGI is composed of a Public Land Mobile Network (PLMN) identity (PLMN ID) to which the cell belongs and an NR Cell Identity (NCI) of the cell. The PLMN ID included in the NCGI is the first PLMN ID within the PLMN ID set associated with the NR cell identity in system information block type 1 (SIB 1). The "gNB identifier" (gNB ID) is used to identify a particular gNB within the PLMN. The gNB ID is contained within the NCI of its cell. The "global gNB ID" is used to globally identify the gNB, and is composed of the PLMN identity to which the gNB belongs and the gNB ID. The Mobile Country Code (MCC) and Mobile Network Code (MNC) are the same as both included in the NCGI.

Cells serving a particular geographic area are grouped into coverage areas (e.g., tracking areas) belonging to a PLMN. In this example, different groups of cells serve different countries, although other types of cell groupings are possible.

It will be appreciated that the NTN node 5 may not broadcast an associated PLMN ID for its cell(s). Thus, the mobile device 3 accessing the NTN cell may not be able to determine which PLMN (and which country/region) the cell belongs to. However, in this system, the node may be configured to ensure that the mobile device 3 is using the correct AMF for the geographical area (in this case the country) in which the mobile device 3 is located.

In more detail, the mobile device 3 is configured to provide the appropriate location assistance information to its new serving base station 6 when the mobile device 3 attempts to resume its RRC connection via the new cell served by that base station 6. The assistance information may be, for example, global Navigation Satellite System (GNSS) location information, MCC (of the mobile device) and/or any other suitable positioning information. Based on this information, the new serving base station 6 (or the previous serving base station 6) can determine whether the UE context and AMF associated with the mobile device 3 are suitable for use in the area/country/PLMN/cell in which the mobile device 3 is currently located, and the base station 6 can manage the RRC connection accordingly.

If the new base station 6 determines, based on location assistance information and/or UE context from the old base station 6, that the previously used AMF cannot be used for the new cell, the base station may send the mobile device 3 appropriate redirection information for registering with the new AMF appropriate to the country/PLMN in which the mobile device 3 is currently located.

User Equipment (UE)

Fig. 2 is a block diagram showing main components of the mobile apparatus (UE) 3 shown in fig. 1. As shown, the UE 3 includes transceiver circuitry 31, which transceiver circuitry 31 is operable to transmit signals to and receive signals from connected node(s) via one or more antennas 33. Although not necessarily shown in fig. 2, the UE 3 will of course have all the usual functions of a conventional mobile device, such as the user interface 35 or the like, and this may suitably be provided by any one or any combination of hardware, software and firmware. The controller 37 controls the operation of the UE 3 according to software stored in the memory 39. For example, the software may be pre-installed in the memory 39 and/or may be downloaded via the telecommunication network 1 or from a removable data storage device (RMD). The software includes an operating system 41, a communication control module 43, and a positioning module 45, among others.

The communication control module 43 is responsible for handling (generating/transmitting/receiving) signaling messages and uplink/downlink data packets between the UE 3 and other nodes including the NTN node 5, (R) AN node 6 and the core network node. The signaling may include control signaling related to UE context retrieval/redirection to the new AMF.

The positioning module 45 (which is optional in some UEs) is responsible for determining the position of the UE 3, e.g. based on GNSS signals, and for providing position assistance information to other nodes when appropriate.

NTN node (satellite/UAS platform)

Fig. 3 is a block diagram illustrating the main components of the NTN node 5 (satellite or UAS platform) shown in fig. 1. As shown, the NTN node 5 comprises transceiver circuitry 51 operable to transmit signals to and receive signals from the connected UE(s) 3 via one or more antennas 53, and to transmit signals to and receive signals from other network nodes (such as gateways and base stations, etc.), directly or indirectly. The controller 57 controls the operation of the NTN node 5 according to software stored in the memory 59. For example, the software may be pre-installed in the memory 59 and/or may be downloaded via the telecommunication network 1 or from a removable data storage device (RMD). The software includes an operating system 61 and a communication control module 63, among others.

The communication control module 63 is responsible for handling signaling (generation/transmission/reception) between the NTN node 5 (via the base station/gateway) and other nodes such as UE 3, base station 6, gateway and core network nodes etc. The signaling may include control signaling related to UE context retrieval/UE redirection to the new AMF.

Base station/gateway (access network node)

Fig. 4 is a block diagram showing the main components of the gateway 6 (base station (gNB) or similar access network node) shown in fig. 1. As shown, gateway/gNB 6 includes transceiver circuitry 71, which transceiver circuitry 71 is operable to transmit signals to and receive signals from connected UE(s) 3 via one or more antennas 73, and to transmit signals to and receive signals from other network nodes (directly or indirectly) via a network interface 75. Signals may be transmitted to and received from the UE(s) 3 directly and/or via the NTN node 5 as appropriate. The network interface 75 typically includes a suitable base station-base station interface (such as X2/Xn, etc.) and a suitable base station-core network interface (such as S1/NG-C/NG-U, etc.). The controller 77 controls the operation of the base station 6 according to software stored in the memory 79. For example, the software may be pre-installed in the memory 79 and/or may be downloaded via the telecommunication network 1 or from a removable data storage device (RMD). The software includes an operating system 81 and a communication control module 83, among others.

The communication control module 83 is responsible for handling (generating/transmitting/receiving) signaling between the base station 6 and other nodes, such as the UE 3, NTN node 5 and core network node, etc. The signaling may include control signaling related to UE context retrieval/UE redirection to the new AMF.

Detailed Description

Some exemplary procedures of UE redirection in the system shown in fig. 1 (solutions 1 to 5) are described below with reference to the scenarios shown in fig. 5 and 6.

Specifically, in the scenario shown in fig. 5, the new base station 6-2 (gNB 2) serves more than one country or more than one coverage area (i.e., the gNB2 controls cells in different countries (denoted "country X" and "country Y" in fig. 5). In this scenario, the base station 6-2 has connectivity with different AMFs 9-1 and 9-2 serving the corresponding PLMNs 8-1 and 8-2 in different countries/regions. The base station 6-2 has cells providing coverage to UEs 3 in different countries/regions, i.e. in this example, cells a and B provide coverage in country X (or coverage area X) and cell C provides coverage in country Y (or coverage area Y). One or more cells of base station 6-2 may not broadcast the PLMN IDs included in the global gNB ID associated with base station 6-2.

In the scenario shown in fig. 6, the new base station 6-2 has cell coverage in different countries/regions due to coverage area overflows (which may be caused by movement of the NTN node 5) crossing the boundary between different countries/regions. As in the previous scenario, the base station 6-2 has connectivity with different AMFs 9-1 and 9-2 serving the respective PLMNs 8-1 and 8-2 in different countries/regions.

In the above scenario, UE 3 establishes an RRC connection with a base station via a cell and registers with the AMF in the country/region/PLMN served by the base station. In the example shown in fig. 5 and 6, UE 3 (initially) establishes an RRC connection via "cell a" of base station 6-1 ("gNB 1") and registers with AMF 9-1 in "country X" (PLMN 8-1). When the UE 3 is subsequently released to the RRC inactive state, the RRC connection is suspended and the associated UE context is stored by the base station 6-1 ("gNB 1", which may be referred to as the UE's previous/old serving gNB) once the UE is in the RRC inactive state.

Later, when UE 3 attempts to restore the RRC connection, UE 3 may be located in another cell. In this example, the UE 3 is in a cell C in a different country (country Y/PLMN 8-2) belonging to a different base station 6-2 ("gNB 2" or "new gNB"). Thus, the UE 3 attempts to restore the RRC connection via the base station 6-2 in the PLMN 8-2/cell C in country Y. In this example, it is assumed that gNB1 and/or gNB2 has connectivity with AMF 9-1 of serving country X (of PLMN 8-1) and AMF 9-2 of serving country Y (of PLMN 8-2).

To avoid using unsuitable UE contexts at the new base station 6-2 (in the new country or new region), the nodes of the system are configured to do one or more of the following solutions.

Solution 1

Fig. 7 is a signaling (timing) diagram illustrating an exemplary manner in which UE context retrieval and subsequent UE redirection may occur in the above scenario.

It can be seen that UE 3 is initially in RRC inactive state. The associated UE context is stored at the old base station 6-1 (gNB 1) of the UE. The UE context relates to the coverage area (country) in which the base station 6-1 is located (or the country/region in which the base station 6-1 is serving).

In step S1, the UE 3 sends a properly formatted "RRC resume request" message to the new base station 6-2 (gNB 2), which includes assistance information related to the UE location. The information may be, for example, global Navigation Satellite System (GNSS) location information, MCC, and/or any other suitable positioning information. In this and the following examples, the "RRC resume request" message is sent to initiate a RAN-based notification area (RNA) update, although the RRC connection may be resumed for other purposes if appropriate.

In step S2, the new base station 6-2 generates and transmits a "retrieve UE context request (RETRIEVE UE CONTEXT REQUEST)" message of an appropriate format to the old serving base station 6-1, and the new base station 6-2 may include the location assistance information received from the UE in the message. The information elements used in the message and some other details will be summarized in the next section.

In step S3, the old serving base station 6-1 decides, based on the received assistance information and the stored UE context related to the UE 3, that the UE location in country Y (where the UE 3 is currently located) does not match the previously registered stored UE context on AMF 9-1 from country X serving (corresponding to the earlier location of the UE). Thus, the old serving base station 6-1 selects AMF 9-2 to serve the UE 3 located in country Y based on the received assistance information.

The old serving base station 6-1 replies to the new base station 6-2 with a "retrieve UE context failure (RETREIVE UE CONTEXT FAILURE)" message (step S5) comprising an RRC release (RRCRelease) message (to be forwarded by the new base station 6-2 to the UE 3) to move the UE 3 to rrc_idle. Further, the "retrieve UE context failure" message includes an appropriate cause value (e.g., "location not supported" and/or the like) to indicate a cause for which the UE context cannot be provided to the new base station 6-2. The old serving base station 6-1 may also include redirection information for redirecting the UE 3 to the PLMN 8-2 (i.e. to register with AMF 9-2 of the serving country Y).

In step S7, the new serving base station 6-2 sends an "RRC release" message to the UE 3 and may include redirection information for AMF 9-2/PLMN 8-2. In effect, the RRC release message instructs the UE 3 to enter a so-called RRC idle state and to delete the context associated with the old base station 6-1.

The old serving base station 6-1 also generates and sends a properly formatted "UE context release request (UE CONTEXT RELEASE REQUEST)" message to the old AMF 9-1 in step S8, the "UE context release request" message including the appropriate cause value ("location not supported" and/or the like).

In step S9, the AMF 9-1 releases the UE context in the old serving base station 6-1 (e.g., using an AMF-initiated UE context release procedure).

As generally shown in step S10, the UE 3 may use the redirection information (if received) for subsequent registration on AMF 9-2 of the country Y in which the serving UE 3 is located.

The UE 3 may perform a subsequent RRC setup procedure with the new serving base station 6-2 and (assuming that the UE 3 is located in country Y) register with the appropriate AMF 9-2 of the serving country Y.

Retrieving UE context requests

The message is sent by the new NG-RAN node (gNB 2) to request the old NG-RAN node (gNB 1) to transfer the UE context to the new NG-RAN.

The direction is: the new NG-RAN node goes towards the old NG-RAN node.

In this example, retrieving the UE context request message includes the location assistance information in an appropriate Information Element (IE) (e.g., assistance information related to the UE location or positioning IE and/or the like). The message may also include one or more information elements indicating the type of location assistance information (e.g., in a "location information indicator" IE or the like) and information related to the time and validity of the location assistance information (e.g., a date stamp IE/validity IE).

Solution 2

Fig. 8 is a signaling (timing) diagram illustrating another exemplary manner in which UE context retrieval and subsequent UE redirection may occur in the above scenario. In this case, the new base station 6-2 determines that the UE context is related to the AMF in another country/another coverage area.

Initially, UE 3 is in RRC inactive state and the associated UE context is stored at the old base station 6-1 (gNB 1) of the UE.

In step S1, the UE 3 generates an appropriately formatted "RRC restoration request" message including assistance information related to the UE location and transmits the message to the new base station 6-2 (gNB 2). The information may be, for example, GNSS location information, MCC, and/or any other suitable positioning information.

In step S2, the new base station 6-2 and the old base station 6-1 perform a UE context retrieval procedure (which includes the new base station 6-2 sending a "retrieve UE context request" and receiving an appropriate "retrieve UE context response (RETRIEVE UE CONTEXT RESPONSE)") from the old base station 6-1. During this UE context retrieval procedure, the new base station 6-2 receives UE contexts related to the previous registration of the UE. Thus, as shown in step S3, the new serving base station 6-2 determines that the UE location in country Y (where UE 3 is currently located) does not match the previously registered UE context on AMF 9-1 serving country X (corresponding to the earlier location of the UE) based on the received assistance information and UE context related to UE 3.

Thus, the new serving base station 6-2 generates a "path switching request" of an appropriate format including the assistance information received from the UE 3 in step S4 and transmits the "path switching request" to the AMF 9-1.

The old AMF 9-1 determines that it does not support the current UE location (country Y) and rejects the path switch request by generating a "path switch request reject" message in the appropriate format with the appropriate cause value ("location not supported") and sending this message to the base station 6-2 (step S5). Additionally, AMF 9-1 may also send information regarding the redirection of UE 3 to the appropriate AMF 9-2 of serving country Y.

In step S7, the new serving base station 6-2 sends an "RRC release" message to the UE 3 and may include redirection information for AMF 9-2/PLMN 8-2. Based on the RRC release message, UE 3 enters an RRC idle state and deletes the context associated with the old base station 6-1.

In steps S9a and S9b, AMF 9-1 initiates a release of UE context in the old serving base station 6-1 and the new serving base station 6-2 (e.g., using an AMF initiated UE context release procedure).

The UE 3 may perform a subsequent RRC setup procedure with the new serving base station 6-2 and register with the appropriate AMF 9-2 of the serving country Y.

Solution 3

Fig. 9 is a signaling (timing) diagram illustrating another exemplary manner in which UE context retrieval may be performed in the above scenario.

Initially, UE 3 is in RRC inactive state and the associated UE context is stored at the old base station 6-1 (gNB 1) of the UE. In this case, the UE 3 provides location assistance information when it enters the RRC connected state.

In more detail, the UE 3 sends an appropriately formatted "RRC resume request" message to the new base station 6-2 (gNB 2). However, the message does not include information related to the UE location, or the information (if included) may not be processed by the new base station 6-2 at this stage.

In step S2, the new base station 6-2 and the old base station 6-1 perform the UE context retrieval procedure as described above, and the new base station 6-2 receives the UE context related to the previous registration of the UE.

In this case, the new base station 6-2 instructs the UE 3 to resume the RRC connection (by sending an RRC resume (rrreport) message), and the UE 3 enters the RRC connected state. In step S4, the UE 3 generates and transmits to the new base station 6-2 an appropriately formatted "RRC restoration complete" message including assistance information related to the UE location (e.g., GNSS location information, MCC and/or any other suitable positioning information).

As shown in step S6, the new serving base station 6-2 checks, based on the location assistance information (reported in step S4 or alternatively in step S1), whether the current location of the UE (in country Y) matches a previously registered UE context on AMF 9-1 from country X serving (corresponding to the earlier location of the UE). If the UE 3 is located in country Y (served by AMF 9-2), the new serving base station 6-2 determines that the retrieved UE context (associated with AMF 9-1) is not suitable for the UE location in country Y.

Thus, the new serving base station 6-2 generates and sends to the UE 3 an RRC release message of a suitable format in step S7, which may also include information about the redirection to the PLMN 8-2 of country Y (served by AMF 9-2). This causes the UE 3 to enter an RRC idle state and delete the context associated with the old base station 6-1.

The new serving base station 6-2 also transmits a UE context release message of an appropriate format to the old serving base station 6-1 in step S8, and then the old base station 6-1 and the old AMF 9-1 perform an appropriate UE context release procedure (step S9).

The UE 3 may perform a subsequent RRC setup procedure with the new serving base station 6-2 and register with the appropriate AMF 9-2 of the serving country Y.

Solution 4

Fig. 10 is a signaling (timing) diagram illustrating yet another exemplary manner in which UE context retrieval may be performed. In this case, the new base station 6-2 determines that the UE context stored in the old base station 6-1 is not suitable for the current location of the UE.

In more detail, UE 3 is initially in RRC inactive state and the associated UE context is stored at the old base station 6-1 (gNB 1) of the UE.

In step S1, the UE 3 generates and sends to the new base station 6-2 (gNB 2) an "RRC resume request" message in a suitable format, which includes assistance information related to the UE location (e.g. GNSS location information, MCC and/or any other suitable positioning information).

As shown in step S3, the new base station 6-2 checks based on the location assistance information whether the current location of the UE (in country Y) matches the country or region in which the old base station 6-1 of the UE is located (in this case country X corresponding to the earlier location of the UE). The new base station 6-2 decides not to retrieve the UE context from the old base station 6-1 (although these base stations may be connected via an appropriate Xn interface) because the UE context from the old base station 6-1 and/or any associated AMFs would not fit in the reported (in this example, country Y) UE location. For example, the new base station 6-2 may be aware that the old base station 6-1 is located in country X served by AMF 9-1/PLMN 8-1. Such information may be obtained from information exchanged between base stations 6-1 and 6-2 during Xn setup (between gNB2 and gNB 1) regarding the PLMNs they support (e.g., PLMN list) and/or the coverage areas they support.

Thus, the new serving base station 6-2 generates and sends to the UE 3 an RRC release message of a suitable format in step S7, which may also include information about the redirection to the PLMN 8-2 of country Y (served by AMF 9-2). This causes the UE 3 to enter an RRC idle state and delete the context associated with the old base station 6-1.

The new serving base station 6-2 also transmits a UE context release message of an appropriate format to the old serving base station 6-1 in step S8, and then the old base station 6-1 and the old AMF 9-1 perform an appropriate UE context release procedure (step S9).

If appropriate, the UE 3 may perform an RRC setup procedure with the new serving base station 6-2 and register with the appropriate AMF 9-2 of the serving country Y.

RRC release message (solutions 1 to 4)

The following is an overview of RRC release messages and associated information elements that may be sent by the base station 6 (e.g., the gNB 2) to request the UE 3 to select and register with an appropriate AMF for the UE's location. In this example, the RRC release message includes a suitable IE (e.g., a "redirect plmnamfinfo" IE and/or the like) for identifying the PLMN (e.g., based on its associated PLMN identity) and AMF (using a "repolectedamf" IE and/or the like) to be used in the cell of the new base station 6-2 (in fig. 5 and 6). An RRC release ("RRCRelease") message is used herein as an exemplary message for indicating AMF registration of UE 3 with the location (current country/region) of the serving UE. It will be appreciated that other suitable messages may be used, such as RRC reject messages or RRC redirect messages and/or the like. The names of the information elements are also used herein as examples. Other suitable information elements (or information) may be used if appropriate, such as "PLMN name", "PLMN index", "AMF name", "AMF address", "AMF group", "core network identifier", and/or the like.

Modifications and substitutions

The detailed embodiments are described above. As will be understood by those skilled in the art, many modifications and substitutions may be made to the above-described embodiments while still benefiting from the invention embodied in such modifications and substitutions. Many such substitutions and modifications will now be described by way of illustration only.

It will be appreciated that the above embodiments may be applied to both the 5G new air interface and the LTE system (E-UTRAN). A base station (gateway) supporting the E-UTRA/4G protocol may be referred to as "eNB" and a base station supporting the next generation/5G protocol may be referred to as "gNB". It will be appreciated that some base stations may be configured to support both 4G and 5G protocols, and/or any other 3GPP or non-3 GPP communication protocols.

It will be appreciated that in the NTN deployment scenario, a base station (NG-RAN node) may serve multiple countries/regions using multiple cells (scenario 1) or using a single cell (scenario 2). In this case, the base station may broadcast (using different cells or a single cell) an appropriate indication of its serving multiple countries/regions via an appropriate System Information Block (SIB). The indication may take the form of 1 bit and may have the following values and interpretation:

"1" ue needs to provide its location when accessing the cell(s) of the NG-RAN node

The "0" ue does not need to provide its location to the NG-RAN node.

The location measurement/reporting capable UE may be configured to provide its location as part of RRC messaging with the NG-RAN (e.g., in an RRC resume request or RRC resume complete message). Alternatively, a UE with location measurement/reporting capability (e.g., GNSS, etc.) may be configured to release itself and enter the rrc_idle state when out of range enters a different country or a different coverage area. UEs that do not have location measurement/reporting capabilities (e.g., no GNSS, MCC, etc.) may be prevented from accessing a new NG-RAN node in another country/coverage area.

Section 10.1 of 3GPP TR 38.857V18.0.0 provides further information regarding positioning for UEs in the rrc_inactive state. In summary, the following positioning techniques are considered:

-Downlink (DL), uplink (UL) and dl+ul positioning methods;

-UE-based and UE-assisted positioning solutions;

-support of UE positioning measurements for UEs in rrc_inactive state;

options that may be considered include downlink positioning reference signals (DL-PRS) or DL-PRS and Synchronization Signal Blocks (SSB);

support of gNB positioning measurements for UEs in rrc_inactive state.

In order to enable UE positioning in rrc_inactive state, the following technique may be used:

UL reference signals for UL measurements (e.g., sounding Reference Signals (SRS) for positioning, physical Random Access Channel (PRACH) preambles);

signaling and procedures to support assistance data delivery, DL-PRS configuration, UL reference signals for positioning resource configuration, measurement reporting, which may be developed based on enhancements of existing signaling and procedures (e.g., existing 2-step and/or 4-step PRACH procedures, paging procedures, small data transmissions).

The following procedure may be used for DL positioning in rrc_inactive:

-reporting of DL-PRS measurements and/or position estimates made in rrc_inactive while the UE is in rrc_inactive;

-enabling reporting of DL-PRS measurements and/or position estimates made in rrc_inactive while the UE is in rrc_inactive by enhancing small data transmissions in rrc_inactive;

-an on-demand system information request in rrc_inactive for assistance data delivery by broadcast in rrc_inactive;

provideasistancedata in rrc_connected configured for DL-PRS used in rrc_inactive downlink positioning;

For DL-PRS measurements or position estimation made in rrc_inactive, a requestlocalinformation information may be sent in rrc_connected.

It will be appreciated that the UE may be configured to derive its location using any of the techniques described above, and that the UE may provide location assistance information accordingly.

TABLE 1 types of satellite and UAS platforms

It will be appreciated that there are various architecture options to implement NTN in a 5G system, some of which are schematically shown in fig. 11. The first option shown is NTN featuring an access network serving the UE and based on a satellite/antenna with a bent-tube payload and a gNB (satellite hub or gateway level) on the ground. The second option is NTN featuring an access network serving the UE and based on a satellite/antenna with an on-board gNB. A third option is NTN featuring an access network serving the relay node and based on satellites/antennas with bent-tube payloads. A fourth option is NTN featuring an access network serving the relay node and based on satellites/antennas with the gNB. It will be appreciated that other architectural options may also be used, for example, a combination of two or more of the options described above. Alternatively, the relay node may comprise a satellite/UAS.

In the above description, for ease of understanding, the UE, NTN node (satellite/UAS platform) and access network node (base station) are described as having a plurality of discrete modules (such as communication control modules, etc.). While these modules may be provided for some applications in this manner, for example where an existing system has been modified to implement the present invention, in other applications, such as in a system designed from the outset to take into account the use of inventive features, these modules may be built into the overall operating system or code, and thus may not be discernable as discrete entities. These modules may also be implemented in software, hardware, firmware, or a mixture of these.

The controllers may include any suitable form of processing circuitry including, but not limited to, for example: one or more hardware-implemented computer processors; a microprocessor; a Central Processing Unit (CPU); an Arithmetic Logic Unit (ALU); an input/output (IO) circuit; internal memory/cache (program and/or data); a processing register; a communication bus (e.g., a control, data, and/or address bus); a Direct Memory Access (DMA) function; hardware or software implemented counters, indicators and/or timers; and/or the like.

In the above embodiments, a plurality of software modules are described. As will be appreciated by those skilled in the art, the software modules may be provided in compiled or uncompiled form and may be supplied as signals to the UE, NTN node and access network node (base station) over a computer network or on a recording medium. Furthermore, one or more dedicated hardware circuits may be used to perform some or all of the functions performed by the software. However, the use of software modules is preferred because the software modules facilitate updating the UE, NTN node and access network node (base station) to update their functionality.

The above embodiments are also applicable to "non-mobile" or generally fixed user equipment. The mobile devices described above may include MTC/IoT devices and/or the like.

The information related to the location of the UE may include at least one of a Global Navigation Satellite System (GNSS) based location and a Mobile Country Code (MCC) associated with the UE.

The method performed by the UE may include: transmitting the information related to the location of the UE in at least one of an RRC restoration request message and an RRC restoration complete message.

The method performed by the UE may further include: information is received for redirecting the UE to an AMF associated with a location of the UE. For example, the method may include: an RRC release message or RRC reject message including the information for redirecting the UE to the AMF associated with the location of the UE is received. The method performed by the UE may further include: setting up an RRC connection via the second cell; and selecting an AMF based on the received information.

The method performed by the UE may further include: receiving, in the second cell (e.g., via system information), an indication of whether to transmit information related to a location of the UE; and transmitting the information based on the received indication.

The method performed by the network node may further comprise: transmitting the information related to the location of the UE to the base station; and determining whether to release the RRC connection based on the response from the base station. For example, the method may include: the information is transmitted to the base station in a retrieve UE context request message.

The method performed by the network node may further comprise: transmitting the information related to the location of the UE to an access and mobility management function (AMF) associated with the first coverage area; and determining whether to release the RRC connection based on the response from the AMF. For example, the method may include: the information is transmitted to the AMF in a path switch request message.

The network node may comprise a gateway or a base station device.

The response from the AMF to the network node (second base station) may comprise at least one of: a cause value for identifying that the location is not supported for the UE; and information for redirecting the UE to another AMF associated with the location of the UE.

Various other modifications will be apparent to those skilled in the art and will not be described in further detail herein.

For example, all or part of the exemplary embodiments disclosed above may be described as, but are not limited to, the supplementary description below.

(supplementary notes 1)

A method by a user equipment, UE, configured to communicate via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a first base station associated with a first coverage area stores a UE context associated with suspending a radio resource control, RRC, connection of the UE, the method comprising:

initiating a procedure for resuming the suspended RRC connection via a cell serving a coverage area different from the first coverage area;

transmitting information related to a location of the UE; and

a message for releasing the suspension RRC connection based on the location of the UE is received from a base station controlling a cell serving the different coverage area.

(supplementary notes 2)

The method of claim 1, wherein the information includes at least one of:

a global navigation satellite system based location, i.e. a GNSS based location; and

The mobile country code, MCC, associated with the UE.

(supplementary notes 3)

The method of any of the above 1 or 2, wherein the information is included in at least one of an RRC restoration request message and an RRC restoration complete message.

(supplementary notes 4)

The method of any one of instructions 1 to 3, further comprising: information is received for redirecting the UE to a core network node for mobility management associated with a location of the UE.

(supplementary notes 5)

The method of claim 4, wherein the information for redirecting the UE is included in an RRC release message or an RRC reject message.

(supplementary notes 6)

The method of either of descriptions 4 or 5, further comprising:

setting up an RRC connection via cells serving the different coverage areas; and

the core network node is selected based on information for redirecting the UE.

(supplementary notes 7)

The method of any one of instructions 1 to 6, further comprising:

an indication of whether to transmit information related to the location of the UE is received in a cell serving the different coverage area,

wherein transmitting the information is based on the indication.

(supplementary notes 8)

A method by a user equipment, UE, configured to communicate via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein the UE has a suspended radio resource control, RRC, connection associated with a first coverage area, the method comprising:

Determining that the current location of the UE is in a coverage area different from the first coverage area; and

the suspension RRC connection is released based on the current location of the UE.

(supplementary notes 9)

A method by a network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a base station associated with a first coverage area stores UE context associated with a suspension of a radio resource control connection, i.e. suspension of an RRC connection, of the UE, the method comprising:

receiving a message from the UE to initiate a procedure for resuming the suspension of RRC connection via a cell serving a coverage area different from the first coverage area;

receiving information related to a location of the UE; and

and transmitting a message for releasing the suspension RRC connection based on the position of the UE to the UE.

(supplementary notes 10)

The method of claim 9, further comprising:

transmitting the information to the base station;

receiving a response to the information from the base station; and

determining whether to release the suspended RRC connection based on the response.

(supplementary notes 11)

The method of claim 10, wherein transmitting the information to the base station comprises: transmitted in a retrieve UE context request message.

(supplementary notes 12)

The method of claim 9, further comprising:

transmitting the information to a core network node for mobility management associated with the first coverage area;

receiving a response to the information from the core network node; and

determining whether to release the suspended RRC connection based on the response.

(supplementary notes 13)

The method of claim 12, wherein transmitting the information to the core network node comprises: transmitted in a path switch request message.

(supplementary notes 14)

The method of any of claims 10 to 13, wherein the response comprises at least one of:

a cause value for identifying that the location is not supported for the UE; and

information for redirecting the UE to a core network node for mobility management associated with a location of the UE.

(supplementary notes 15)

A method performed by a network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein the network node stores UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, of the UE in relation to a first coverage area, the method comprising:

Receiving information related to a location of the UE from a base station serving a second coverage area via a cell; and

and transmitting a response for releasing the suspended RRC connection to the base station in the case that the first coverage area and the second coverage area are different.

(supplementary notes 16)

The method of claim 15, wherein the information is included in a retrieve UE context request message.

(supplementary notes 17)

The method of any of claims 9 to 16, wherein the network node comprises a gateway or a base station.

(supplementary notes 18)

A method by a core network node for mobility management, the core network node being configured to communicate with user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a first base station stores UE context associated with a suspended radio resource control, RRC, connection of the UE in relation to the first coverage area, the method comprising:

receiving information related to a location of the UE from a base station serving a second coverage area via a cell; and

and transmitting a response for releasing the suspension RRC connection to a base station serving the second coverage area in the case that the first coverage area and the second coverage area are different.

(supplementary notes 19)

The method of claim 18, wherein the response includes at least one of:

a cause value for identifying that the location is not supported for the UE; and

information for redirecting the UE to another core network node for mobility management associated with a location of the UE.

(supplementary notes 20)

A user equipment, UE, configured to communicate via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a first base station associated with a first coverage area stores UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, of the UE, the UE comprising:

means for initiating a procedure for resuming the suspended RRC connection via a cell serving a coverage area different from the first coverage area;

means for transmitting information related to a location of the UE; and

means for receiving a message for releasing the suspension of the RRC connection based on the location of the UE from a base station for controlling a cell serving the different coverage area.

(supplementary notes 21)

A user equipment, UE, configured to communicate via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein the UE has a UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, with respect to a first coverage area, the UE comprising:

Means for determining that a current location of the UE is in a different coverage area than the first coverage area; and

means for releasing the suspended RRC connection based on the current location of the UE.

(supplement description 22)

A network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a base station associated with a first coverage area stores UE context associated with a suspended radio resource control, RRC, connection of the UE, the network node comprising:

means for receiving a message from the UE to initiate a procedure for resuming the suspension of RRC connection via a cell serving a coverage area different from the first coverage area;

means for receiving information related to a location of the UE; and

means for transmitting a message to the UE to release the suspension of RRC connection based on the location of the UE.

(supplementary notes 23)

A network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein the network node stores UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, of the UE with respect to a first coverage area, the network node comprising:

Means for receiving information related to a location of the UE from a base station serving a second coverage area via a cell; and

transmitting a response to the base station to release the suspended RRC connection if the first coverage area and the second coverage area are different.

(supplementary notes 24)

A core network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a first base station stores UE context associated with a suspended radio resource control, RRC, connection of the UE with respect to the first coverage area, the core network node comprising:

means for receiving information related to a location of the UE from a base station serving a second coverage area via a cell; and

and transmitting a response for releasing the suspension of the RRC connection to a base station serving the second coverage area in case the first coverage area and the second coverage area are different.

The present application is based on and claims the priority rights of uk patent application 2105402.8 filed on 4/15 of 2021 and uk patent application 2106477.9 filed on 5/6 of 2021, the disclosures of which are incorporated herein by reference in their entirety.

List of reference numerals

1. Mobile telecommunication system

3. User of mobile device

5. Satellite

6. Base station

7. Data network

31. Transceiver circuit

33. Antenna

35. User interface

37. Controller for controlling a power supply

39. Memory device

41. Operating system

43. Communication control module

45. Positioning module

51. Transceiver circuit

53. Antenna

57. Controller for controlling a power supply

59. Memory device

61. Operating system

63. Communication control module

71. Transceiver circuit

73. Antenna

75. Network interface

77. Controller for controlling a power supply

79. Memory device

81. Operating system

83. Communication control module

Claims (24)

1. A method by a user equipment, UE, configured to communicate via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a first base station associated with a first coverage area stores a UE context associated with suspending a radio resource control, RRC, connection of the UE, the method comprising:

initiating a procedure for resuming the suspended RRC connection via a cell serving a coverage area different from the first coverage area;

transmitting information related to a location of the UE; and

a message for releasing the suspension RRC connection based on the location of the UE is received from a base station controlling a cell serving the different coverage area.

2. The method of claim 1, wherein the information comprises at least one of:

a global navigation satellite system based location, i.e. a GNSS based location; and

the mobile country code, MCC, associated with the UE.

3. The method according to claim 1 or 2, wherein the information is included in at least one of an RRC resume request message and an RRC resume complete message.

4. A method according to any one of claims 1 to 3, further comprising: information is received for redirecting the UE to a core network node for mobility management associated with a location of the UE.

5. The method of claim 4, wherein the information for redirecting the UE is included in an RRC release message or an RRC reject message.

6. The method of claim 4 or 5, further comprising:

setting up an RRC connection via cells serving the different coverage areas; and

the core network node is selected based on information for redirecting the UE.

7. The method of any one of claims 1 to 6, further comprising:

an indication of whether to transmit information related to the location of the UE is received in a cell serving the different coverage area,

Wherein transmitting the information is based on the indication.

8. A method by a user equipment, UE, configured to communicate via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein the UE has a suspended radio resource control, RRC, connection associated with a first coverage area, the method comprising:

determining that the current location of the UE is in a coverage area different from the first coverage area; and

the suspension RRC connection is released based on the current location of the UE.

9. A method by a network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a base station associated with a first coverage area stores UE context associated with a suspension of a radio resource control connection, i.e. suspension of an RRC connection, of the UE, the method comprising:

receiving a message from the UE to initiate a procedure for resuming the suspension of RRC connection via a cell serving a coverage area different from the first coverage area;

receiving information related to a location of the UE; and

And transmitting a message for releasing the suspension RRC connection based on the position of the UE to the UE.

10. The method of claim 9, further comprising:

transmitting the information to the base station;

receiving a response to the information from the base station; and

determining whether to release the suspended RRC connection based on the response.

11. The method of claim 10, wherein transmitting the information to the base station comprises: transmitted in a retrieve UE context request message.

12. The method of claim 9, further comprising:

transmitting the information to a core network node for mobility management associated with the first coverage area;

receiving a response to the information from the core network node; and

determining whether to release the suspended RRC connection based on the response.

13. The method of claim 12, wherein transmitting the information to the core network node comprises: transmitted in a path switch request message.

14. The method of any of claims 10 to 13, wherein the response comprises at least one of:

a cause value for identifying that the location is not supported for the UE; and

Information for redirecting the UE to a core network node for mobility management associated with a location of the UE.

15. A method performed by a network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein the network node stores UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, of the UE in relation to a first coverage area, the method comprising:

receiving information related to a location of the UE from a base station serving a second coverage area via a cell; and

and transmitting a response for releasing the suspended RRC connection to the base station in the case that the first coverage area and the second coverage area are different.

16. The method of claim 15, wherein the information is included in a retrieve UE context request message.

17. The method of any of claims 9 to 16, wherein the network node comprises a gateway or a base station.

18. A method by a core network node for mobility management, the core network node being configured to communicate with user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a first base station stores UE context associated with a suspended radio resource control, RRC, connection of the UE in relation to the first coverage area, the method comprising:

Receiving information related to a location of the UE from a base station serving a second coverage area via a cell; and

and transmitting a response for releasing the suspension RRC connection to a base station serving the second coverage area in the case that the first coverage area and the second coverage area are different.

19. The method of claim 18, wherein the response comprises at least one of:

a cause value for identifying that the location is not supported for the UE; and

information for redirecting the UE to another core network node for mobility management associated with a location of the UE.

20. A user equipment, UE, configured to communicate via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a first base station associated with a first coverage area stores UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, of the UE, the UE comprising:

means for initiating a procedure for resuming the suspended RRC connection via a cell serving a coverage area different from the first coverage area;

means for transmitting information related to a location of the UE; and

Means for receiving a message for releasing the suspension of the RRC connection based on the location of the UE from a base station for controlling a cell serving the different coverage area.

21. A user equipment, UE, configured to communicate via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein the UE has a UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, with respect to a first coverage area, the UE comprising:

means for determining that a current location of the UE is in a different coverage area than the first coverage area; and

means for releasing the suspended RRC connection based on the current location of the UE.

22. A network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a base station associated with a first coverage area stores UE context associated with a suspended radio resource control, RRC, connection of the UE, the network node comprising:

means for receiving a message from the UE to initiate a procedure for resuming the suspension of RRC connection via a cell serving a coverage area different from the first coverage area;

Means for receiving information related to a location of the UE; and

means for transmitting a message to the UE to release the suspension of RRC connection based on the location of the UE.

23. A network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein the network node stores UE context associated with suspending a radio resource control connection, i.e. suspending an RRC connection, of the UE with respect to a first coverage area, the network node comprising:

means for receiving information related to a location of the UE from a base station serving a second coverage area via a cell; and

transmitting a response to the base station to release the suspended RRC connection if the first coverage area and the second coverage area are different.

24. A core network node configured to communicate with a user equipment, UE, via a non-terrestrial network comprising a plurality of cells, each cell serving at least one coverage area, wherein a first base station stores UE context associated with a suspended radio resource control, RRC, connection of the UE with respect to the first coverage area, the core network node comprising:

Means for receiving information related to a location of the UE from a base station serving a second coverage area via a cell; and

and transmitting a response for releasing the suspension of the RRC connection to a base station serving the second coverage area in case the first coverage area and the second coverage area are different.