Method, user equipment, and network node

Abstract

A method is disclosed that is performed by a user equipment (UE) configured to communicate over a network including a non-terrestrial network portion. The method includes performing a procedure that includes performing measurements on at least one cell in a set of candidate cells and performing cell selection based on results of the measurements. The procedure is performed based on at least one parameter for the at least one cell including at least one of: a remaining serving time of each of the at least one cell, a distance between a current location of the UE and each of the at least one cell, a distance between a current location of the UE and a serving cell, and a mobility of the UE.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system operating according to the specifications of the 3rd Generation Partnership Project (3GPP (registered trademark)), and its devices or their equivalents or derivatives. The present disclosure is particularly related to improvements in mobility in so-called "5G" (or "next generation") systems that employ a non-terrestrial portion including aerial or space network nodes, although not exclusively.

Background Art

[0002] Under the 3GPP specifications, a NodeB (or "eNB" in LTE and "gNB" in 5G) is a base station for a communication device (user equipment or "UE") to connect to a core network and communicate with other communication devices or remote servers. End-user communication devices are generally called user equipment (UE) and may include devices operated by humans or automated devices. Such communication devices may be, for example, mobile communication devices such as mobile phones, smartphones, smartwatches, personal digital assistants, laptop / tablet computers, web browsers, e-book readers, connected vehicles, etc. Such mobile (or generally fixed) devices are usually operated by users (thus, they are often collectively called user equipment "UE"), but it is also possible to connect Internet of Things (IoT) devices and similar machine type communications (MTC) devices to the network. For simplicity, this application uses the term base station to refer to such a base station and the term mobile device or UE to refer to such a communication device.

[0003] The latest developments of the 3GPP specifications are the so-called "5G" or "New Radio" (NR) specifications, which refer to an evolving communication technology expected to support various applications and services such as MTC, IoT / Industrial Internet of Things (IIoT) communications, vehicle communications and autonomous vehicles, high-resolution video streaming, smart city services, etc. 3GPP intends to support 5G by means of the so-called 3GPP Next Generation (NextGen) Radio Access Network (RAN) / Radio Access Technology (RAT), and the 3GPP NextGen core (NGC) network. Various details of the 5G network are described, for example, in Non-Patent Document 1.

[0004] 3GPP is also working on the specification of the infrastructure of integrated satellite and terrestrial networks in the context of 4G and 5G. The term Non-Terrestrial Networks (NTN) refers to a network or a segment of a network that uses an aircraft or a spacecraft for transmission. A satellite refers to a spacecraft in a non-geostationary earth orbit (NGEO) such as a geostationary earth orbit (GEO), or a low earth orbit (LEO), a medium earth orbit (MEO), and a highly elliptical orbit (HEO). An aircraft refers to a high altitude platform (HAP) that includes unmanned aircraft systems (UAS), such as tethered UAS, lighter than air UAS, and heavier than air UAS, all of which typically operate in a quasi-stationary state at an altitude of 8 to 50 km.

[0005] Non-Patent Document 2 is a study on new radio for supporting such non-terrestrial networks. This study includes, among other things, descriptions of NTN deployment scenarios and related system parameters (such as architecture, altitude, orbit, etc.), and the adaptation of 3GPP channel models for non-terrestrial networks (propagation conditions, mobility, etc.). Non-Patent Document 3 provides further details on NTN.

[0006] Non-terrestrial networks can - help promote the deployment of 5G services in areas where services are not provided or are insufficient to improve the performance of terrestrial networks, - enhance service reliability by providing service continuity for user equipment or for mobile platforms (such as passenger vehicles - aircraft, ships, high-speed trains, buses). - Improve service availability in all locations, especially for critical communications and future railway / maritime / aviation communications, and - Enable the scalability of 5G networks by providing efficient multicast / broadcast resources for delivering data towards the network edge or directly to user equipment.

[0007] NTN access typically (among other things) features the following elements. - NTN terminals: May refer to 3GPP UEs or terminals specific to the satellite system when the satellite does not directly provide services to 3GPP UEs. - A service link that refers to the radio link between the user equipment and the space / aviation platform (which may be added to the radio link with the terrestrial-based RAN). - A space or aviation platform. - A gateway (the "NTN gateway") that connects the satellite or aviation access network to the core network. It will be understood that the gateway is typically located in the same place as the base station. - A feeder link that refers to the radio link between the gateway and the space / aviation platform.

[0008] A satellite or aircraft may generate several beams over a given area to provide each respective NTN cell. The beams typically have an elliptical footprint on the Earth's surface.

[0009] 3GPP defines - Geostationary cells (e.g., GEO satellites and HAPS) characterized by beams that always cover the same geographical area, and - Quasi-geostationary cells (e.g., NGEO satellites that generate steerable beams) characterized by beams that cover one geographical area over a finite period and different geographical areas during different periods. It is intended to support three types of NTN beams or cells with a beam that covers one geographical area at any given moment and a different geographical area at another moment, such as an earth moving cell (e.g., an NGEO satellite that generates a fixed beam or a non-steerable beam).

[0010] For a given point on the earth, such as a satellite or aircraft that maintains a fixed position with respect to elevation / azimuth for GEO and UAS, the beam footprint is fixed to the earth.

[0011] For a satellite that orbits the earth in a circular path (e.g., LEO) or an elliptical orbit around the earth (e.g., HEO), the beam footprint may move across the earth with the movement of the satellite or aircraft in its orbit. Alternatively, the beam footprint may be temporarily earth-fixed (or quasi-earth-fixed), in which case an appropriate beam pointing mechanism (mechanical or electronic steering) may be used to compensate for the movement of the satellite or aircraft.

[0012] LEO satellites can have steerable beams, in which case the beams are temporarily directed towards a substantially fixed footprint on the Earth. In other words, the beam footprints (representing NTN cells) remain stationary on the ground for a certain period of time before changing their focus areas to another NTN cell due to the movement of the satellite in its orbit. From the perspective of cell coverage / UE, since it is necessary to assign different Physical Cell Identities (PCIs) and / or Synchronization Signal / Physical Broadcast Channel (PBCH) blocks (Synchronization Signal / Physical Broadcast Channel: SSB) for each service link change, even when these beams provide services to the same terrestrial area (have the same footprint), cell changes will occur periodically at discontinuous intervals. LEO satellites without steerable beams, as the satellite moves along its orbit, cause beams (cells) that constantly move across the ground in a sweeping motion like in the case of steerable beams, and service link changes, and consequently cell changes, occur periodically at discontinuous intervals. Similar to service link changes, feeder link changes also occur at regular intervals due to the movement of the satellite in its orbit. Changes in both service links and feeder links can be carried out between different base stations / gateways (sometimes referred to as "radio link switches between gNBs") or within the same base station / gateway ("radio link switches within gNB").

[0013] In the 3GPP system, cell selection and reselection are facilitated by a base station that broadcasts appropriate information (e.g., parameters / thresholds used and / or UE measurements performed) for calculating the relevant cell (re)selection criterion "S". Based on this, the UE can evaluate whether to select a particular cell to camp on (e.g., when the UE is operating in the RRC idle or inactive state). Similarly, such a cell selection criterion S can be used when selecting an appropriate handover cell (e.g., an adjacent cell). The cell selection criterion S includes a set of sub-criteria including, for example, a "Srxlev" sub-criterion that specifies a cell selection receiver (RX) level value (dB), and a "Squal" sub-criterion that specifies a cell selection quality value (dB). For a given cell, the cell selection criterion S is satisfied when Srxlev > 0 and Squal > 0 (for that cell).

[0014] According to Non-Patent Document 4, when the Srxlev / Squal of the serving cell is higher than their configured thresholds, the UE may not need to measure intra-frequency cells and / or inter-frequency cells of equal or lower priority. However, the UE is always expected to measure inter-frequency cells of high priority.

[0015] Non-Patent Document 4 also stipulates rules for relaxed measurements, such as relaxed measurement criteria for a specific UE. In summary, relaxed measurements (e.g., less frequent measurements) can be applied for UEs with low mobility (criterion: the signal strength change of the serving cell over any duration is less than the relevant threshold), and / or UEs that are not at the cell edge (criterion: the signal strength of the serving cell is better than the associated threshold).

[0016] In the case of NR inter-frequency and RAT inter-cell reselection, as well as in the case of intra-frequency and equal-priority inter-frequency cell reselection, several special criteria may apply. In such cases, - For the case of high-priority inter-frequency: Always select that frequency when the cell on that frequency meets the relevant signal strength or quality threshold, - When frequencies are within or between equal priorities: Execute cell reselection based on ranking (i.e., reselection to the best available cell with the same priority), and - When between low - priority frequencies: Select a frequency only when the serving cell signal is worse than the relevant threshold and the cell on the frequency is better than the relevant threshold. As such, cell reselection to a high - priority RAT / frequency cell is prioritized over a low - priority RAT / frequency cell.

Prior Art Documents

Non - Patent Documents

[0017]

Non - Patent Document 1

Non - Patent Document 2

Non - Patent Document 3

Non - Patent Document 4

Non - Patent Document 5

Non - Patent Document 6

Non - Patent Document 7

Summary of the Invention

Problems to be Solved by the Invention

[0018] The inventors have identified at least the following problems regarding current methods when applied to cells in an NTN network. - The NTN cell is characterized in that the signal strength variation from the cell center to the cell edge is relatively small compared to the signal strength variation of a conventional non-NTN cell (see FIGS. 5A and 5B). Therefore, since it may be difficult for the UE to distinguish between the cell center and the cell edge based on the signal strength, and / or since the difference between two cells becomes relatively small as the UE approaches the edge of a candidate cell, it may be difficult to detect an appropriate neighboring cell with a significantly better signal strength than the current cell (for cell reselection purposes). Thus, signal strength-based cell reselection may not function well for NTN cells. - In an NTN system, a given cell (e.g., cell A) can be switched off and another cell (e.g., cell B) can be switched on and replace it. The new cell (cell B) does not necessarily have to cover the same area as the cell that has been switched off (cell A). In this case, all UEs camping on the affected cell need to reselect another cell. Ideally, these UEs should avoid reselection to the same cell (cell A) if that cell is about to disappear. Such a cell switch-off can occur due to satellite movement and / or any other reason, e.g., switching of service links and feeder links as shown in FIGS. 6A and 6B. A cell (e.g., an NTN cell) may also be switched on / off to optimize the cell capacity (in a terrestrial network). For example, a cell may be switched off due to relatively low traffic / fewer RRC connections in that cell (and can be switched on due to high traffic / load in the terrestrial network).

[0019] This disclosure aims to provide methods and related apparatuses that address or at least mitigate (at least some of) the above problems.

Means for Solving the Problems

[0020] In one aspect, the present disclosure provides a method performed by a user equipment (UE) configured to communicate via a network comprising a non-terrestrial network portion, the method comprising performing measurements on at least one cell within a set of candidate cells, and performing cell selection based on the results of those measurements and at least one of respective timing information and location information regarding that set of candidate cells, the method comprising excluding from those measurements, or from that cell selection, at least one candidate cell having a remaining service provision time less than a first threshold, excluding at least one candidate cell from those measurements, or from that cell selection, if a distance from the UE's current location to its serving cell is less than a second threshold, applying relaxed measurements to at least one candidate cell if a distance from the UE's current location to its serving cell is less than a third threshold, applying relaxed measurements to at least one candidate cell if the UE's mobility is lower than a fourth threshold, and excluding at least one candidate cell from those measurements, or from that cell selection, if a distance from the UE's current location to that candidate cell is greater than a fifth threshold, comprising at least one of.

[0021] In one aspect, the present disclosure provides a method performed by a network node configured to communicate with a user equipment (UE) via a network comprising a non-terrestrial network portion, the method comprising providing configuration information to the UE, performing measurements on at least one cell within a set of candidate cells, and performing cell selection based on the results of those measurements and at least one of the respective timing information and location information regarding that set of candidate cells, wherein providing the configuration information includes adapting the configuration information to assist the UE, and the configuration information excludes at least one candidate cell having a remaining service provision time less than a first threshold from those measurements or from that cell selection, excludes at least one candidate cell from those measurements or from that cell selection when the distance from the UE's current location to its serving cell is less than a second threshold, applies relaxed measurements to at least one candidate cell when the distance from the UE's current location to its serving cell is less than a third threshold, applies relaxed measurements to at least one candidate cell when the UE's mobility is lower than a fourth threshold, and excludes at least one candidate cell from those measurements or from that cell selection when the distance from the UE's current location to that candidate cell is greater than a fifth threshold, and includes at least one threshold for the UE to use.

[0022] In one aspect, the present disclosure provides a user equipment (UE) configured to communicate via a network comprising a non-terrestrial network portion, the UE comprising means (e.g., memory, transceiver, and processor) for performing measurements on at least one cell within a set of candidate cells, and means for performing cell selection based on the results of those measurements and at least one of the respective timing information and location information regarding that set of candidate cells, the UE excluding from those measurements or from that cell selection at least one candidate cell having a remaining service provision time less than a first threshold, excluding from those measurements or from that cell selection at least one candidate cell if the distance from the UE's current location to its serving cell is less than a second threshold, applying relaxed measurements to at least one candidate cell if the distance from the UE's current location to its serving cell is less than a third threshold, applying relaxed measurements to at least one candidate cell if the UE's mobility is lower than a fourth threshold, and excluding from those measurements or from that cell selection at least one candidate cell if the distance from the UE's current location to that candidate cell is greater than a fifth threshold, and being configured to perform at least one of the foregoing.

[0023] In one aspect, the present disclosure provides a network node configured to communicate with a user equipment (UE) via a network comprising a non-terrestrial network portion, the network node being means (e.g., a memory, a transceiver, and a processor) for providing configuration information to the UE, the means performing, for at least one cell in a set of candidate cells, performing measurements, and based on the result of the measurements and at least one of respective timing information and location information regarding the set of candidate cells, performing cell selection, the configuration information including means adapted to assist the UE, the configuration information excluding from the measurement or the cell selection at least one candidate cell having a remaining associated service providing time less than a first threshold, excluding from the measurement or the cell selection at least one candidate cell when the distance from the current location of the UE to its serving cell is less than a second threshold, applying relaxed measurements to at least one candidate cell when the distance from the current location of the UE to its serving cell is less than a third threshold, applying relaxed measurements to at least one candidate cell when the mobility of the UE is lower than a fourth threshold, and excluding from the measurement or the cell selection at least one candidate cell when the distance from the current location of the UE to the candidate cell is greater than a fifth threshold, and including at least one threshold for the UE to use, of at least one of the above.

[0024] Aspects of the present disclosure extend to computer program products, such as computer-readable storage media storing corresponding systems, apparatuses, and instructions, to program a programmable processor to perform the methods described above or as described in the claims and / or to program a computer suitably adapted to provide the apparatus described in any of the claims, and are operable.

[0025] Each feature disclosed in this specification (including the claims) and / or shown in the drawings can be incorporated into the present disclosure independently of (or in combination with) any other disclosed and / or shown feature. In particular, without limitation, any feature of any dependent claim subordinate to a particular independent claim can be introduced into that independent claim in any combination or individually.

Brief Description of the Drawings

[0026] Here, embodiments of the present disclosure will be described by way of example with reference to the accompanying drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 6A

Figure 6B

Figure 7

Embodiments for Carrying Out the Invention

[0027] Overview FIG. 1 is a schematic diagram of a mobile (cellular or wireless) telecommunications system 1 to which embodiments of the present disclosure may be applied.

[0028] In this system 1, a user of a mobile device 3 (UE) can communicate with each other and with other users via access network nodes, namely satellite 5 and / or base station 6, and data network 7, using an appropriate 3GPP radio access technology (RAT), such as Evolved Universal Terrestrial Radio Access (E-UTRA), and / or 5G RAT. As will be understood by those skilled in the art, although two mobile devices 3, one satellite 5, and one base station 6 are shown in FIG. 1 for illustrative purposes, the system, when implemented, will typically include other satellite / UAS platforms, base stations / RAN nodes, and mobile devices (UEs).

[0029] It will be appreciated that some base stations 6 form a (radio) access network or (R)AN, and some NTN nodes 5 (satellites and / or UAS platforms) form a non-terrestrial network (NTN). Each NTN node 5 is connected to an appropriate gateway using a so-called feeder link (which is in this case co-located with base station 6) and is connected to each UE 3 via a corresponding service link. Thus, when served by an NTN node 5, the mobile device 3 communicates data with the base station 6 via the NTN node 5 using an appropriate service link (between the mobile device 3 and the NTN node 5) and a feeder link (between the NTN node 5 and the gateway / base station 6). In other words, the NTN forms part of the (R)AN but can provide satellite communication services independently of E-UTRA (or "4G") and / or New Radio (or "5G") communication services.

[0030] Although not shown in FIG. 1, adjacent base stations 6 are connected to each other via an appropriate inter-base-station interface (e.g., a so-called "X2" interface, "Xn" interface, etc.). The base stations 6 are also connected to a data network node via an appropriate interface (e.g., a so-called "S1", "NG-C", "NG-U" interface, etc.).

[0031] A data (or core) network 7 (e.g., EPC in the case of LTE, NGC in the case of NR / 5G) typically includes logical nodes (or "functions") for supporting communication in the telecommunication system 1, particularly for subscriber management, mobility management, charging, security, call / session management, etc. For example, the data network 7 of a "next-generation" / 5G system includes user plane entities and control plane entities such as one or more control plane functions (CPF) and one or more user plane functions (UPF). The so-called Access and Mobility Management Function (AMF) in 5G or the Mobility Management Entity (MME) in 4G is responsible for handling connection and mobility management tasks of 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).

[0032] Each NTN node 5 controls several directional beams that can provide associated NTN cells. Specifically, each beam has an associated footprint on the surface of the Earth corresponding to the NTN cell. Each NTN cell (beam) has associated physical cell identity (PCI) and / or beam identification information. The beam footprint may move as the NTN node 5 moves along its orbit. Alternatively, the beam footprint may be fixed to the Earth, in which case an appropriate beam pointing mechanism (mechanical or electronic steering) may be used to compensate for the movement of the NTN node 5.

[0033] When the UE3 first establishes an RRC connection with the base station 6 via a cell, it registers an appropriate AMF9 (or MME). The UE3 is in a so-called RRC connected state, and an associated UE context is maintained by the network. When the UE3 is provided with services via the NTN node 5, it transmits and receives data via one of the beams (NTN cells) of the NTN node 5. When the UE3 is in a so-called RRC idle state or RRC inactive state, an appropriate cell needs to be selected for camping so that the network can recognize the approximate location of the UE3 (not necessarily at the cell level).

[0034] Over time, due to the movement of the UE3 and / or the movement of the serving NTN node 5, the UE3 switches from cell to cell (from beam to beam) using appropriate mobility procedures. To do so, the base station 6 provides the UE3 with appropriate configuration data and / or assistance information, based on which the UE3 can determine which cell to use, which cells to measure, and when to switch from any cell to another cell.

[0035] When the UE3 performs cell reselection between NTN cells, its operation may be different from that for non-NTN (terrestrial) cells in terms of its cell reselection operation.

[0036] Specifically, to address the relatively low signal strength variations from the cell center to the cell edge of the NTN cell, UE3 is configured to use location-assisted cell reselection techniques. This enables UE3 to distinguish between the cell center and the cell edge and / or determine when to approach an appropriate neighboring cell for cell reselection (even if the signal strength of the neighboring cell is not better than that of the current cell).

[0037] To address the issue of switching off the NTN cell (e.g., according to the system load), UE3 is configured to use time-assisted cell reselection techniques. Thereby, UE3 can avoid reselection to a cell that is about to be switched off or replaced by another cell. It will be recognized that the location-assisted cell reselection technique and the time-assisted cell reselection technique can be used together if appropriate. Some UE3s (or UE types) may be configured to use the location-assisted cell reselection technique, some UEs may be configured to use the time-assisted cell reselection technique, and some UEs may be configured to use both techniques.

[0038] More specifically, to assist the cell reselection operation, the following four options can be configured for a specific UE3 (or group of UEs).

[0039] Option 1: UE3 can be configured to exclude neighboring cells with a remaining service providing time less than the relevant threshold from cell reselection. Option 2: When the distance of the UE to the serving cell is less than the relevant threshold (i.e., when the UE is relatively close to the cell center or reference point of the current serving cell), UE3 can be configured not to perform measurements on intra-frequency cells and inter-frequency cells (at least cells with a priority lower than or equal to that of the current cell). Option 3: UE3 may be configured to apply relaxed measurements when the distance to the serving cell of the UE is less than the relevant threshold (which may be the same threshold as in Option 2 or a different threshold), and / or when the UE is determined to be a low-mobility UE based on the relevant threshold. And, Option 4: UE3 may be configured to exclude from cell reselection an adjacent cell whose distance from the current location of the UE is greater than the relevant threshold (i.e., when the UE is relatively far from the edge, center, or appropriate reference point of its adjacent cell).

[0040] Typically, these thresholds are configured via broadcast system information and applied to all UE3s camped on the corresponding cell (except when the threshold is associated with a particular UE class / type, in which case the threshold is applied only to those UEs). It will be understood that these thresholds (at least one threshold) may be applied to a particular UE class / type (e.g., IoT UE or power-saving UE instead of all UEs), and (if any) different thresholds may be defined for different UE classes / types. The thresholds may be configured at factory shipment for each UE (e.g., depending on its class / type and / or network operator). If necessary, the thresholds may be (re)configured via dedicated signaling (e.g., RRC signaling using one or more appropriate information elements).

[0041] User Equipment (UE) FIG. 2 is a block diagram showing the main components of the mobile device (UE) 3 shown in FIG. 1. As shown, the UE 3 includes a transceiver circuit 31 operable to transmit signals to and receive signals from a node connected via one or more antennas 33. Although not necessarily shown in FIG. 2, the UE 3 of course has all the normal functions of a conventional mobile device (such as a user interface 35), which may be provided by any one or any combination of hardware, software, and firmware as needed. The control unit 37 controls the operation of the UE 3 according to the software stored in the memory 39. The software may be pre-installed in the memory 39 and / or downloaded, for example, via the telecommunications network 1 or from a removable data storage device (RMD). The software includes, among other things, an operating system 41, a communication control module 43, a mobility module 44, and a positioning module 45 (optional in some UEs).

[0042] 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, the (R)AN node 6, and the core network node. The signaling may include control signaling (such as RRC signaling) related to the configuration and assistance of cell reselection by the UE 3.

[0043] The mobility module 44 is responsible for controlling the mobility procedures of the UE 3 (RRC connected, RRC idle, and RRC inactive states) based on appropriate assistance information (such as configuration / parameters) from the network, such as time and / or position thresholds. The mobility procedures include, for example, (initial) cell selection, cell reselection, handover, provision of location updates to the network, state transitions (such as changing cells), etc.

[0044] When present, the positioning module 45 is responsible for determining the position of the UE3, for example, based on Global Navigation Satellite System (GNSS) signals.

[0045] NTN Node (Satellite / UAS Platform) FIG. 3 is a block diagram showing the main components of the NTN node 5 (satellite or UAS platform) shown in FIG. 1. As shown, the NTN node 5 includes a transceiver circuit 51 operable to transmit signals to and receive signals from the connected UE3 via one or more antennas 53, and to transmit signals to and receive signals from other network nodes such as a gateway and a base station (directly or indirectly). The control unit 57 controls the operation of the NTN node 5 according to software stored in the memory 59. The software may be pre-installed in the memory 59 and / or may be downloaded, for example, via the telecommunications network 1 or from a removable data storage device (RMD). The software includes, among other things, an operating system 61, a communication control module 63, and a mobility control module 64.

[0046] The communication control module 63 is responsible for handling (generating / transmitting / receiving / relaying) signaling between the NTN node 5 and other nodes such as the UE3, the base station 6, the gateway, and the core network node (via the base station / gateway). The signaling may include control signaling (such as RRC (radio resource control) signaling) related to the configuration and assistance of cell reselection by the UE3.

[0047] The mobility control module 64 is responsible for controlling the mobility procedures (RRC connection, RRC idle, and RRC inactive states) of the UE3 by sending appropriate assistance information (e.g., configuration / parameters) such as time and / or location thresholds to the UE3. The assistance information / thresholds may be provided by the gateway 6 to which the NTN node 5 is connected. The mobility procedures include, for example, (initial) cell selection, cell reselection, handover, providing location updates to the network, state transitions (e.g., changing cells), etc.

[0048] Base station / gateway (access network node) Figure 4 is a block diagram showing the main components of the gateway 6 (base station (gNB), or a similar access network node) shown in Figure 1. As shown, the gateway / gNB 6 includes a transceiver circuit 71 operable to transmit signals to and receive signals from the connected UE3 via one or more antennas 73, and to transmit signals to and receive signals from other network nodes (directly or indirectly) via the network interface 75. The signals may be transmitted to and received from the UE3 directly and / or via the NTN node 5 as required. The network interface 75 typically includes appropriate base station-base station interfaces (such as X2 / Xn) and appropriate base station-core network interfaces (such as S1 / NG-C / NG-U). The control unit 77 controls the operation of the base station 6 according to the software stored in the memory 79. The software may be pre-installed in the memory 79 and / or downloaded, for example, via the telecommunications network 1 or from a removable data storage device (RMD). The software includes, among other things, an operating system 81, a communication control module 83, and a mobility control module 84.

[0049] 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, the NTN node 5, and the core network node. The signaling may include control signaling (such as RRC signaling) related to the configuration and support of cell reselection by the UE 3.

[0050] The mobility control module 84 is responsible for controlling the mobility procedures (RRC connection, RRC idle, and RRC inactive states) of the UE 3 by providing appropriate assistance information (such as configuration / parameters) to the UE 3, such as time and / or position thresholds. The mobility procedures may include, for example, (initial) cell selection, cell reselection, handover, providing location updates to the network, state transitions (such as changing cells), and the like.

[0051] Details The following is an explanation of some exemplary cell (re)selection procedures implemented by the nodes of the system shown in FIG. 1. This procedure may be particularly beneficial in the exemplary scenarios shown in FIGS. 5A, 5B, 6A, and 6B.

[0052] When the Srxlev / Squal of the serving cell is higher than the configured threshold, the UE may be configured not to measure intra-frequency cells and / or inter-frequency cells of equal or lower priority. However, the UE always measures inter-frequency cells of high priority. More specifically, Section 5.2.4.2 of Non-Patent Document 4 describes the following measurement rules for cell reselection used by the UE to limit the necessary measurements. - When the serving cell satisfies Srxlev > S IntraSearchP and Squal > S IntraSearchQ the UE may be selected not to perform intra-frequency measurements. The "Srxlev" cell selection sub-criterion specifies the cell selection receiver (RX) level value (in dB), and the "Squal" cell selection sub-criterion specifies the cell selection quality value (in dB). S IntraSearchPis a power threshold associated with the Srxlev lower criterion of the serving cell for performing in - frequency measurements, and S IntraSearchQ is a quality threshold associated with the Squal lower criterion of the serving cell for performing in - frequency measurements. - Otherwise (i.e., when the serving cell does not satisfy Srxlev > S IntraSearchP and Squal > S IntraSearchQ for one or both), the UE shall perform in - frequency measurements. - For NR inter - frequency and RAT - to - RAT frequencies with priorities indicated in the system information and defined in section 5.2.4.1 of Non - Patent Document 4, the UE shall apply the following rules: - In the case of an NR inter - frequency or RAT - to - RAT frequency having a reselection priority higher than that of the current NR frequency, the UE shall perform measurements on the higher - priority NR inter - frequency or RAT - to - RAT frequency in accordance with Non - Patent Document 5. - In the case of NR inter - frequencies having a reselection priority equal to or lower than that of the current NR frequency, and in the case of RAT - to - RAT frequencies having a reselection priority lower than that of the current NR frequency, - When the serving cell satisfies Srxlev > S nonIntraSearchP and Squal > S nonIntraSearchQ the UE can choose not to perform measurements on NR inter - frequency cells with equal or lower priority, or RAT - to - RAT frequency cells with lower priority. - Otherwise, i.e., when the serving cell does not satisfy at least one of Srxlev > S IntraSearchP and Squal > S IntraSearchQ the UE shall perform measurements on NR inter - frequency cells with equal or lower priority, or RAT - to - RAT frequency cells with lower priority in accordance with Non - Patent Document 5. - When the UE supports relaxed measurements and the information element (IE) relaxed measurements are present in the system information block type 2 (SIB2), the UE may further relax the necessary measurements as specified in item 5.2.4.9 of Non - Patent Document 4.

[0053] In this system, the UE3 may be configured to use location-assisted cell reselection technology. This technology can be used in NTN cells where the signal strength variation from the cell center to the cell edge is relatively low. Alternatively or additionally, the UE3 may also be configured to use time-assisted cell reselection technology. This technology may be used in NTN cells that can be switched on and off (e.g., according to the system load).

[0054] It will be understood that some UE3s (or some types / classes of UEs) may be configured to use location-assisted cell reselection technology, some UEs may be configured to use time-assisted cell reselection technology, and some UEs may be configured to use both location-assisted cell reselection technology and time-assisted cell reselection technology.

[0055] Time-assisted cell reselection Regarding time-assisted (or time-based) cell reselection, based on the latest agreement in 3GPP, the following assumptions apply. - For quasi-geostationary cells, in the case of a geostationary cell scenario, the timing information about when to stop providing service to an area is broadcast to the UE via system information. Usually, in the case of quasi-geostationary cells, since the beam covers one geographical area (i.e., the quasi-geostationary cell) over a finite period and different geographical areas over another period, it is provided via an NGEO satellite using a steerable beam. - For quasi-geostationary cells, the timing information about when the cell stops providing service to an area refers to the time when the cell stops covering the current area. The timing information is broadcast within the cell. - For quasi-geostationary cells, the UE3 starts measuring its neighboring cells (which are candidates for cell selection) before the stop time of the serving cell indicated via the timing information. In other words, the UE3 tries to complete the measurement and cell reselection before the serving cell stops covering the current area to avoid going out of coverage.

[0056] The following is an illustration of an exemplary method (Option 1) in which timing information of neighboring cells (e.g., cell outage time) can be used to assist cell reselection by UE3.

[0057] Option 1 UE3 may be configured to exclude neighboring cells having a remaining service time less than a relevant threshold from cell reselection.

[0058] Timing information about when a particular neighboring cell will stop serving the area is broadcast to UE3 via system information. This information may be broadcast for at least some NTN cells, such as quasi-geostationary cells. This information may be obtained via OAM configuration and / or shared between neighboring base stations 6 via an inter-base station interface between the neighboring base stations 6. The time threshold (also referred to as the "first threshold" or "first exclusion threshold") may be configured via system information.

[0059] UE3 in the idle state or non-active state may read system information, perform measurements, and perform cell reselection by taking into account any timing information and any other applicable configurations.

[0060] Specifically, in this case, if the remaining service time of that cell (the time until the cell stops serving the current area) is less than the time threshold associated with that cell, UE3 is configured to exclude any cell from measurement. In other words, even if a particular cell is the best cell in terms of frequency, UE3 does not measure that cell (or ignores the relevant measurement results) and does not reselect that cell if the timing information indicates that the cell will stop providing service to the current area relatively soon.

[0061] Location-assisted cell reselection Regarding location assisted (or location based) cell reselection, the following assumptions apply based on the latest agreement in 3GPP. For a quasi geostationary cell, the reference position of the cell (serving cell or neighboring cell) is broadcast in the system information. The reference position is defined as the cell center (however, any other appropriate reference position may be used if necessary). - If UE3 has valid (recent or current) location information, location assisted cell reselection based on the distance between UE3 and the reference position of the cell (serving cell and / or neighboring cell) is supported for quasi geostationary cells. It should be understood that location acquisition is not triggered on the UE side only for location assisted cell reselection (however, it may be possible in some cases).

[0062] The following describes some exemplary ways (referred to as "Option 2" to "Option 4") in which location information can be used to assist cell reselection by UE3. The location information may be applicable to the distance between UE3 and the reference position of its serving cell and / or the distance between UE3 and the reference position of a neighboring cell (i.e., a candidate for cell selection).

[0063] Option 2 If the distance of the UE to the serving cell is less than the relevant threshold (i.e., the UE is relatively close to the cell center or reference point of the current serving cell), UE3 may be configured not to perform measurements in certain neighboring frequencies / cells, such as intra-frequency cells and inter-frequency cells (at least cells having a priority lower than or equal to that of the current cell). If UE3 performs measurements on such cells, UE3 may be configured to exclude or ignore these measurements in its cell reselection process.

[0064] More specifically, the reference position of the serving cell (e.g., the cell center on the ground), or information related to the reference position of the serving cell (e.g., ephemeris information), is broadcast / transmitted to the UE3 via, for example, system information. This information may be broadcast for at least some NTN cells such as quasi-geostationary cells, and this information may be shared between adjacent base stations. The base station 6 may configure at least one distance threshold (e.g., the "second threshold" or the "first exclusion threshold") associated with the serving cell to determine when to stop / trigger the measurement of adjacent cells at a specific frequency or of a specific type of the adjacent cells, and may assist the UE3. It will be appreciated that different associated second thresholds may be configured for different adjacent cells, different frequencies, and / or different cell types.

[0065] Option 2-1: Only one distance threshold applicable to all adjacent cells.

[0066] Option 2-2: Multiple distance thresholds, in which case: - One distance threshold may be applicable for each frequency, or, - One distance threshold may be applicable to inter-frequency cells (having equal or lower priority), and another distance threshold may be applicable to intra-frequency cells, or, - One distance threshold may be applicable to each adjacent cell type, e.g., TN adjacent frequency / cell, GEO adjacent frequency / cell, LEO adjacent frequency / cell, etc.

[0067] If UE3 has valid location information for itself, before proceeding to perform measurements related to cell reselection, it calculates the distance to the reference position of the serving cell. If the distance from the UE's position to the serving cell reference position is less than the configured second threshold, UE3 does not perform measurements on the corresponding adjacent frequency, cell, or cell type (however, UE3 may still perform measurements on other cells to which different thresholds apply or for which no threshold applies). If the distance from the UE's position to the serving cell reference position is greater than (or at least equal to) the configured second threshold, UE3 performs measurements on the corresponding adjacent frequency / cell / type and proceeds to perform cell reselection based on the results of these measurements.

[0068] Option 3 UE3 may be configured to apply relaxed measurements if at least one of the following conditions is met: - the distance of the UE to the serving cell is less than the relevant threshold related to the cell edge (i.e., the threshold for determining whether UE3 is at the cell edge), and - the speed of the UE is slower than the relevant threshold or the change in the UE's position is less than the relevant threshold (i.e., the threshold for determining low mobility). Relaxed measurements for intra-frequency cells, inter-frequency cells, and inter-RAT frequency cells are performed according to the relaxation methods in Sections 4.2.2.9, 4.2.2.10, and 4.2.2.11 of Non-Patent Document 5.

[0069]

[0070] Base station 6 may broadcast parameters related to location-assisted cell reselection by UE3. These parameters may be applicable at least to UE3 not located at or near the edge of the serving cell. To assist in determining whether UE3 is located at the cell edge, base station 6 broadcasts (or provides) the relevant distance threshold (e.g., "third threshold" or "first relaxation threshold").

[0071] ​If UE3 has valid position information for itself, it can calculate the distance to the reference position of the serving cell. If the distance to the serving cell reference position is less than the configured (third) threshold, UE3 can apply relaxed measurements for all or some of the adjacent frequencies / cells / cell types.

[0072] Also, the base station 6 may broadcast parameters related to position-assisted cell reselection by UE3 with low mobility. Specifically, the parameters may include at least one of a speed threshold or a position change threshold (e.g., "fourth threshold" or "first relaxation threshold") within a configured time window. Thus, in this case, the fourth threshold may be used to determine low mobility and may be provided in the form of a speed threshold or a position change threshold.

[0073] If UE3 has valid position information for itself, UE3 can calculate its speed or the rate of position change within a configured time window.

[0074] If the speed of the UE is less than the configured speed threshold, or if the position change of the UE is less than the position change threshold (within the configured time window), UE3 applies relaxed measurements to all or some of the adjacent frequencies / cells / cell types.

[0075] In summary, UE3 applies relaxed measurements by considering at least one threshold associated with the serving cell, where the at least one threshold may include at least one of a distance threshold, a speed threshold, and a position change threshold.

[0076] Option 4 UE3 may be configured to exclude adjacent cells where the distance from the current position of the UE is greater than the relevant threshold (i.e., when the UE is relatively far from the edge, center, or appropriate reference point of its adjacent cells) from cell reselection.

[0077] More specifically, the base station 6 may broadcast ephemeris information of adjacent cells and / or information identifying respective reference positions associated with the adjacent cells.

[0078] The base station 6 may also broadcast an appropriate distance threshold (also referred to as the "fifth threshold" or "second exclusion threshold") associated with a specific adjacent cell (or group of cells). The base station 6 may broadcast a plurality of distance thresholds for each adjacent cell, or each type of adjacent cell, for example, distance thresholds for each satellite type (GEO, MEO, LEO, non-satellite, etc.). Alternatively, the fifth threshold may be provided for each adjacent cell or frequency.

[0079] The UE 3 may calculate the distance to any indicated / detected adjacent cell based on its current position and the reference position associated with the adjacent cell. If the distance to a specific adjacent cell is greater than the corresponding distance threshold, the UE 3 does not reselect that cell. In other words, the UE 3 may be configured to exclude one or more adjacent cells or frequencies from cell reselection based on the relevant fifth threshold.

[0080] Modifications and Alternatives The detailed embodiments have been described above. It will be understood by those skilled in the art that several modifications and alternatives can be made to the above embodiments while still obtaining benefits from the disclosure embodied therein. By way of example, only some of these alternatives and modifications are described here.

[0081] The above-mentioned threshold values are applicable to a specific UE class / type (e.g., IoT UE or power-saving UE, not all UEs), and it will be understood that different threshold values can be defined for different UE classes / types. The threshold values can be (re)configured via dedicated signaling. The dedicated signaling can comprise appropriately formatted RRC signaling (e.g., RRC connection reconfiguration message, etc.) including one or more information elements. The one or more information elements can include information identifying at least one threshold value and / or information identifying at least one UE category (e.g., UE class / type). However, the threshold values (or default values) may be configured at factory shipment for each UE (e.g., according to its class / type and / or network operator). It will be understood that different threshold values (or different sets of threshold values) can be configured for different types of satellites (GEO, MEO, LEO, etc.).

[0082]

Table 1

[0083] The above exemplary procedures are described in the context of cell reselection (in RRC idle state or RRC inactive state), but it will be understood that the same approach can be applied to other types of mobility procedures, such as (initial) cell selection, cell measurement / selection for handover, etc. It will be understood that similar time and / or location threshold values can be used in other types of procedures, such as cell measurement or cell selection for carrier aggregation / dual connectivity / supplementary uplink.

[0084] The base stations of a 5G / NR communication system are new radio base stations (「NR-BS」), or are generally referred to as 「gNB」, but it will be understood that these can be referred to using the term 「eNB」 (or 5G / NR eNB) which is normally associated with long term evolution (LTE) base stations (also generally referred to as 「4G」 base stations). Non-Patent Document 6 and Non-Patent Document 7 define, inter alia, the following nodes. gNB: A node that provides NR user plane and control plane protocol terminations towards the UE and is connected to the 5G core network (5GC) via the NG interface. ng-eNB: A node that provides E-UTRA user plane and control plane protocol terminations towards the UE and is connected to the 5GC via the NG interface. En-gNB: A node that provides NR user plane and control plane protocol terminations towards the UE and functions as a secondary node in E-UTRA-NR dual connectivity (EN-DC). NG-RAN node: Either a gNB or an ng-eNB.

[0085] It will be understood that the above embodiments may be applicable to both the 5G new radio system and the LTE system (E-UTRAN). A base station (gateway) that supports the E-UTRA / 4G protocol may be referred to as an "eNB", and a base station that supports the NextGeneration / 5G protocol may be referred to as a "gNB". It will be understood that some base stations may be configured to support both 4G and 5G protocols, and / or any other 3GPP or non-3GPP communication protocols.

[0086] It will be appreciated that there are various architectural options for implementing NTN in a 5G system, some of which are schematically shown in FIG. 7. The first option shown is an NTN that provides services to a UE and features an access network based on satellite / aeronautical with a vent pipe type payload and a terrestrial gNB (satellite hub or gateway level). The second option is an NTN that provides services to a UE and features an access network based on satellite / aeronautical with a gNB mounted thereon. The third option is an NTN that provides services to a relay node and features an access network based on satellite / aeronautical with a vent pipe type payload. The fourth option is an NTN that provides services to a relay node and features an access network based on satellite / aeronautical with a gNB. It will be appreciated that other architectural options, for example, combinations of two or more of the above options may also be used. Alternatively, the relay node may comprise a satellite / UAS. Similar architectural options can be used in a 4G / LTE system, but it will be appreciated that an eNB may be used instead of a gNB, an EPC may be used instead of an NGC, and an appropriate LTE interface may be used instead of the NG interface shown in FIG. 7.

[0087] Each cell has an associated "NR Cell Global Identifier" (NCGI) to globally identify the cell. The NCGI consists of the Public Land Mobile Network (PLMN) identification information (PLMN ID) to which the cell belongs and the NR cell identification information (NR Cell Identity: NCI) of the cell. The PLMN ID included in the NCGI is the first PLMN ID within the set of PLMN IDs associated with the NR cell identification information in System Information Block Type 1 (SIB1). The "gNB Identifier" (gNB ID) is used to identify a specific gNB within a PLMN. The gNB ID is included within the NCI of its cell. The "Global gNB ID" is used to globally identify the gNB and is constructed from the PLMN identification information to which the gNB belongs and the gNB ID. The Mobile Country Code (MCC) and the Mobile Network Code (MNC) are the same as those included in the NCGI.

[0088] 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 several individual modules (such as a communication control module). These modules may be provided in this way for specific applications, for example, in cases where an existing system is modified to implement the present disclosure, or in other applications, such as a system designed from the beginning with the features of the present invention in mind. However, since these modules can be incorporated into the overall operating system or code, these modules may not be identifiable as individual entities. These modules may be implemented in software, hardware, firmware, or a combination thereof.

[0089] Each control unit may include any suitable form of processing circuitry, for example (but not limited to), one or more hardware-implemented computer processors, microprocessors, central processing units (CPUs), arithmetic logic units (ALUs), input / output (I / O) circuits, internal memory / cache (program and / or data), processing registers, communication buses (e.g., control bus, data bus, and / or address bus), direct memory access (DMA) functions, hardware or software-implemented counters, pointers, and / or timers, etc.

[0090] In the above embodiments, some software modules have been described. It will be understood by those skilled in the art that the software modules may be provided in a compiled form or an uncompiled form, and may be supplied as signals to the UE, NTN node, and access network node (base station) via a computer network or a recording medium. Further, the functions implemented by some or all of this software may be implemented using one or more dedicated hardware circuits. However, the use of software modules is preferred because it facilitates the update of the UE, NTN node, and access network node (base station) to update their functions.

[0091] The above embodiments are also applicable to "non-mobile" or generally fixed user equipment. The above-described mobile devices (UEs) may include MTC / IoT devices, power-saving UEs, etc.

[0092] The method implemented by the UE may include obtaining, for each corresponding candidate cell, its respective timing information (e.g., from the system information of the serving cell).

[0093] The method performed by the UE may include obtaining configuration information of a set of at least one candidate cell, including information identifying respective positions associated with a given candidate cell.

[0094] The method performed by the UE may include obtaining at least a part of the configuration information via system information or via dedicated signaling (e.g., RRC signaling including at least one information element).

[0095] The configuration information may include at least one of its first to fifth thresholds. The first to fifth thresholds may be applicable based on the class or type of the UE (e.g., IoT UE and / or power saving UE).

[0096] The remaining service providing time may be determined based on the remaining time until the cell stops providing service in the current area. The distance from the current position of the UE to its serving cell or candidate cell may be determined based on the center point or reference point of the cell (compared to the current position of the UE).

[0097] The method performed by the UE may include excluding at least one in - frequency cell or inter - frequency cell having a priority lower than or equal to the priority of the current cell from the measurement or from the cell selection when the distance from the current position of the UE to its serving cell is smaller than a second threshold.

[0098] The method performed by the UE may further include ranking cells within the set of at least one candidate cell and performing cell selection based on the ranking.

[0099] When performing its measurements and cell selection, the UE may be in the Radio Resource Control (RRC) idle state or the RRC inactive state. The cell selection may include cell reselection (e.g., using the cell selection criteria Srxlev and Squal specified by 3GPP). The measurements may be performed for each cell within the set of at least one candidate cell via the associated Channel State Information Reference Signal (CSI-RS) resource.

[0100] Various other modifications will be apparent to those skilled in the art and are not further elaborated here.

[0101] Some or all of the above exemplary embodiments may be described, without limitation, as follows in the following appendices. (Appendix 1) A method performed by a user equipment (UE) configured to communicate via a network including a non-terrestrial network portion, the method including: performing measurements for at least one cell within a set of candidate cells; performing cell selection based on the results of the measurements; wherein the procedure is performed based on at least one parameter for at least one cell including at least one of: the remaining service providing time of each of the at least one cell; the distance between the current location of the UE and each of the at least one cell; the distance between the current location of the UE and the serving cell; the mobility of the UE; and a method. (Appendix 2) The method according to Appendix 1, wherein the procedure includes excluding measurements of cells having values corresponding to at least one parameter less than a first exclusion threshold from the measurements or from the cell selection. The method according to Appendix 1. (Appendix 3) The method according to Appendix 1, wherein when the mobility of the UE is less than a first relaxation threshold, the procedure includes applying relaxed measurements. The method according to Appendices 1 or 2. (Appendix 4) The procedure includes excluding measurements of cells having values corresponding to at least one parameter greater than a second exclusion threshold from measurements or from cell selection. The method according to any one of Appendices 1 to 3. (Appendix 5) The procedure includes performing inter-frequency cell measurements and intra-frequency cell measurements. The value of the threshold applied to the procedure is different between inter-frequency cells and intra-frequency cells. The method according to any one of Appendices 1 to 4. (Appendix 6) The method according to any one of Appendices 1 to 5, wherein the value of the threshold applied to the procedure is different between frequencies at which each of at least one cell is operated. (Appendix 7) The method according to any one of Appendices 1 to 6, wherein the procedure is performed based on the class or type of the UE. (Appendix 8) The method according to any one of Appendices 1 to 7, wherein the remaining service provision time is determined based on the remaining time until the cells corresponding to the remaining service provision time end service provision in the current area. (Appendix 9) The method according to any one of Appendices 1 to 8, wherein the distance from the current position of the UE to each of at least one cell is determined based on the center point or reference point of each of at least one cell. (Appendix 10) The method according to Appendix 9, further comprising receiving position information for identifying a reference position for determining the center point or reference point of each of at least one cell. (Appendix 11) The method according to Appendix 2, wherein the exclusion is performed on cells having a priority lower than or equal to the priority of the serving cell. (Appendix 12) The method according to Appendix 10, wherein receiving the position information includes receiving configuration information including the position information. (Appendix 13) The method according to appendix 11, wherein the configuration information is transmitted via system information or dedicated signaling. (Appendix 14) The method according to appendix 11 or 12, further comprising that the configuration information includes at least one of a first exclusion threshold, a first relaxation threshold, and a second exclusion threshold. (Appendix 15) The method according to any one of appendices 1 to 14, wherein the UE is in the radio resource control (RRC) idle state or the RRC inactive state when executing the procedure. (Appendix 16) The method according to any one of appendices 1 to 15, further comprising receiving at least one parameter via system information. (Appendix 17) Further comprising ranking cells within a set of at least one cell, wherein cell selection is performed based on the ranking. The method according to any one of appendices 1 to 11. (Appendix 18) The method according to any one of appendices 1 to 12, wherein measurements are performed via associated channel state information reference signal (CSI-RS) resources. (Appendix 19) A method performed by a network node configured to communicate with a user equipment (UE) via a network including a non-terrestrial network portion, providing configuration information to the UE, performing measurements on at least one cell within a set of candidate cells, performing cell selection based on the results of the measurements, and wherein, when performing the procedure including the above, the configuration information is configured to assist the UE, and the providing includes the procedure including the remaining service providing time of each of the at least one cell, the distance between the current location of the UE and each of the at least one cell, The distance between the current position of the UE and the serving cell, and the mobility of the UE, and executed based on at least one parameter regarding at least one cell including at least one of them, A method, wherein the configuration information includes at least one threshold for the procedure. (Appendix 20) A user equipment (UE) configured to communicate via a network including a non-terrestrial network portion, wherein the UE performs measurements on at least one cell within a set of candidate cells, and performs cell selection based on the results of the measurements, and is provided with means for performing a procedure including them, the procedure being the remaining service providing time of each of the at least one cell, and the distance between the current position of the UE and each of the at least one cell, and the distance between the current position of the UE and the serving cell, and the mobility of the UE, and executed based on at least one parameter regarding at least one cell including at least one of them. (Appendix 21) A network node configured to communicate with a user equipment (UE) via a network including a non-terrestrial network portion, wherein the network node is means for providing configuration information to the UE, and when performing a procedure including performing measurements on at least one cell within a set of candidate cells and performing cell selection based on the results of the measurements, the configuration information is configured to assist the UE. The procedure being the remaining service providing time of each of the at least one cell, and the distance between the current position of the UE and each of the at least one cell, and the distance between the current position of the UE and the serving cell, and the distance between the current position of the UE and each of the at least one cell, and the distance between the current position of the UE and the serving cell, and UE mobility and At least one parameter related to at least one cell including at least one of the following, a network node executed based on the parameter.

[0102] This application is based on UK Patent Application No. 2115145.1 filed on October 21, 2021, claims the benefit of its priority, and the disclosure thereof is incorporated herein by reference in its entirety.

Explanation of symbols

[0103] 1 Mobile (cellular or wireless) telecommunications system 3 Mobile device 5 Satellite 6 Base station 7 Data (or core) network 31 Transceiver circuit 33 Antenna 35 User interface 37 Control unit 39 Memory 41 Operating system 43 Communication control module 44 Mobility module 45 Positioning module 51 Transceiver circuit 53 Antenna 57 Control unit 59 Memory 61 Operating system 63 Communication control module 64 Mobility control module 71 Transceiver circuit 73 Antenna 75 Network interface 77 Control unit 79 Memory 81 Operating system 83 Communication control module 84 Mobility control module

Claims

1. A user equipment (UE) configured to communicate via a network including a non-terrestrial network, comprising: means for receiving system information including at least one threshold and information indicating a reference position of a serving cell; means for determining not to measure at least one frequency cell having a priority equal to or lower than that of the serving cell when a distance between the current position of the UE and the reference position of the serving cell is smaller than the at least one threshold; comprising; when the system information includes time information indicating a time when the serving cell is about to terminate service in an area currently covered, the determining means is configured to determine whether to measure based on the time information regardless of other conditions, the UE.

2. The determining is performed when the UE has valid information indicating the current position of the UE, The UE according to claim 1.

3. The at least one threshold includes respective thresholds applicable for each frequency, The UE according to claim 1 or 2.

4. The at least one threshold includes a threshold applicable for inter-frequency measurement and a threshold applicable for intra-frequency measurement, The UE according to claim 1 or 2.

5. The at least one threshold includes respective thresholds applicable for each type of neighboring cell, The UE according to claim 1 or 2.

6. The system information includes ephemeris information of adjacent cells, The UE according to claim 1 or 2.

7. A network node configured to communicate with a user equipment (UE) via a network including a non-terrestrial network, comprising: means for transmitting to the UE system information including at least one threshold and information indicating a reference position of a serving cell; the at least one threshold and the reference position of the serving cell are used by the UE to determine not to measure at least one frequency cell having a priority equal to or lower than that of the serving cell when a distance between the current position of the UE and the reference position of the serving cell is smaller than the at least one threshold, When the system information includes time information indicating the time when the serving cell is about to terminate the service in the area it currently covers, it is determined by the UE whether to measure based on the time information regardless of other conditions. Network node. Claim 8 A method in a user equipment (UE) configured to communicate via a network including a non-terrestrial network, comprising: Receiving system information including at least one threshold and information indicating a reference position of a serving cell; When the distance between the current position of the UE and the reference position of the serving cell is less than the at least one threshold, determining not to perform measurements on at least one frequency cell having a priority equal to or lower than that of the serving cell; including A method of determining whether to measure based on the time information regardless of other conditions when the system information includes time information indicating the time when the serving cell is about to terminate the service in the area it currently covers. Claim 9 A method in a network node configured to communicate with a user equipment (UE) via a network including a non-terrestrial network, comprising: Transmitting system information including at least one threshold and information indicating a reference position of a serving cell to the UE, wherein the at least one threshold and the reference position of the serving cell are used by the UE to determine not to perform measurements on at least one frequency cell having a priority equal to or lower than that of the serving cell when the distance between the current position of the UE and the reference position of the serving cell is less than the at least one threshold, When the system information includes time information indicating the time when the serving cell is about to terminate the service in the area it currently covers, it is determined by the UE whether to measure based on the time information regardless of other conditions. Method.

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