User equipment, network entity, telecommunications network and related methods

Abstract

Provided is a method comprising: measuring, by a user equipment, UE, connected to a non-terrestrial network, coverage information indicative of coverage of one or more terrestrial networks available to the UE, the coverage information comprising: a network identifier of the one or more terrestrial networks available to the UE; location information indicating a location of the UE; and a measure of signal strength of the one or more terrestrial networks available to the UE; and communicating, by the UE, the coverage information to the non-terrestrial network. Also provided is a method comprising: receiving, at a network entity of a non-terrestrial network and from a user equipment, UE, connected to the non-terrestrial network, coverage information indicative of coverage of one or more terrestrial networks available to the UE, the coverage information comprising: a network identifier of the one or more terrestrial networks available to the UE; location information indicating a location of the UE; and a measure of signal strength of the one or more terrestrial networks available to the UE; and establishing one or more coverage areas of the one or more terrestrial networks based on the received coverage information.

Description

[0001] User Equipment, Network Entity, Telecommunications Network and Related Methods

[0002] Field

[0003] The present disclosure concerns a User Equipment (UE), a Network Entity, a Telecommunications Network and related methods.

[0004] Background

[0005] It was agreed in Radio Access Network Working Group 2 (RAN2) to provide terrestrial network (TN) coverage information in a non-terrestrial network (NTN) System Information Block (SIB) (the specific SIB is for further study) to assist UEs with NTN to TN mobility. The agreement thus far has been on how to formulate TN coverage information. The TN coverage information is provided by the network via a list of (possibly overlapping) areas, where each area is defined using a centre location coordinates and a radius. The area represents a group of cells. The area’s centre location and its radius for TN coverage information are signalled using Ellipsoid-Point and radius separately, using the same format of Release-17 (Rel-17) referenceLocation and distanceThresh for signalling the TN coverage area centre and radius.

[0006] Even though there is an agreement on the approach to be taken for signalling of TN coverage information, there is no framework on how to obtain the TN coverage information by the NTN network, for preparation for broadcasting the TN coverage information in an NTN SIB.

[0007] To help the UE in efficient measurements towards terrestrial network (TN) coverage, RAN2 has worked on the definition of the TN coverage area. The following has been agreed at RAN2#121 bis (April 2023). For signalling TN coverage, the corresponding geographical area information is provided by broadcast signalling by the network a list of (possibly overlapping) areas, where each area is defined using a centre location coordinate and a radius (where the area is intended to describe a group of cells, and not just a single cell).

[0008] Moreover, the following have been agreed: 1 . Area centre location and its radius for TN coverage information is signalled using Ellipsoid-Point and radius separately. The same format of Rel-17 referenceLocation and distanceThresh will be used for signalling the TN coverage area centre and radius.

[0009] 2. A decision on the size of the TN coverage area list is for further study.

[0010] 3. How to indicate the frequency information for each TN coverage area is for further study.

[0011] 4. The acquired TN area coverage information remains valid until the next system information update of the SIB including TN coverage information.

[0012] 5. No new trigger is introduced to make the UE reacquire the TN coverage information from System Information (SI).

[0013] 6. Radio Resource Control (RRC) dedicated signalling will not be introduced to provide more accurate TN coverage information.

[0014] 7. An RRC_IDLE / RRC_INACTIVE UE is not required to perform neighbour cell measurements for cell reselection for a TN frequency in the area, if configured, where there is no coverage of that frequency, regardless of the frequency priority.

[0015] 8. TN coverage information is not included in SIB19. Whether an existing SIB or a new SIB is to be used is for further study.

[0016] There are several possibilities for how to indicate frequency information for TN coverage:

[0017] • Option 1 : Frequency information (e.g., a list of TN frequencies) for each TN coverage area may be indicated directly under each TN coverage area configuration.

[0018] • Option 2: A TN coverage area configuration may be associated with a TN coverage area identifier (ID). The frequency information for the TN coverage area may be indicated by adding TN coverage area IDs in System Information Block Type 4 (SIB4) and / or System Information Block Type 5 (SIB5).

[0019] • Option 3: A frequency index bitmap may be indicated under each TN coverage area, where the frequency index refers to the frequency’s position in the frequency list of the current SIB4.

[0020] Option 3 is ruled out and a choice between Option 1 and Option 2 is for further study.

[0021] While some progress has been made towards improving performance in systems that use a combination of NTN and TN, there remains a need for further improvements in this area. Summary

[0022] Against this background, the present disclosure provides a method in accordance with claim 1 , a method in accordance with claim 12, one or more UEs in accordance with claim 20, a network entity in accordance with claim 21 , a telecommunications network in accordance with claim 23, a computer program in accordance with claim 24 and a computer-readable medium in accordance with claim 25.

[0023] The present disclosure provides methods and frameworks for obtaining TN (terrestrial network) coverage information, which can be used, for example, to assist with NTN (nonterrestrial network, e.g. a satellite network) to TN mobility. UEs may monitor network coverage of TNs and report coverage information describing the availability of the TNs to an NTN. This coverage information may be monitored and logged continuously, periodically, or in response to a request for the coverage information. The NTN can use the coverage information that it receives to inform any UE connected to the NTN about nearby TNs that are likely to be available to that UE, based on the coverage information reported by the UEs. This can be used to assist with handovers and can improve the efficiency of UEs, since UEs connected to the NTN can be prevented from searching for TNs or can search only for specific TNs that are likely to be available. Some embodiments relate to the way in which UEs measure coverage information and provide the coverage information to an NTN, while some embodiments relate to the way in which an NTN establishes TN coverage areas based on the coverage information that they receive.

[0024] In a first aspect, there is provided a method comprising: measuring, by a UE connected to a non-terrestrial network, coverage information indicative of coverage of one or more terrestrial networks available to the UE, the coverage information comprising: a network identifier of the one or more terrestrial networks available to the UE; location information indicating a location of the UE; and a measure of signal strength of the one or more terrestrial networks available to the UE; and communicating, by the UE, the coverage information to the non-terrestrial network. By providing coverage information from UEs to an NTN, the NTN (or a server connected to the NTN) can calculate the coverage provided by the TNs. This can be used to assist with NTN to TN handover. For instance, if it is already known that a UE on an NTN is not in range of any TNs, then there is no point in the UE attempting to connect to any TNs. Therefore, the information provided by the various UEs on the NTN can be used to prevent wasteful attempts to switch from the NTN to a TN. Additionally or alternatively, the information provided by the various UEs on the NTN can avoid UEs needing to attempt unnecessary measurements on the TN. For the UE, it is relevant to know if it is (potentially) in range of a TN to start measurements. Without this information, the UE has to perform measurements on TN frequencies. With the TN coverage information, the UE can perform the measurements when it is located in the TN coverage area or closer to the TN coverage area. Additionally, further advantages can be realised for relaxing measurements on TN frequencies based on the TN coverage information. Without TN coverage information, the cell reselection will be performed based on frequency priorities. The TN frequency is likely to have a higher reselection priority than the reselection priority of the current NTN frequency. Thus, even without TN coverage, the UE may search for the TN frequency, hence wasting the UE battery.

[0025] Moreover, when it is known that a particular TN is in range of the UE, then it can be advantageous to indicate to the UE that that particular TN is in range, to enable a quick and efficient handover to the TN (which may be the network that is preferred by the UE, with the NTN serving mainly as a backup).

[0026] In a second aspect, there is provided a method comprising: receiving, at a network entity of a non-terrestrial network and from a user equipment, UE, connected to the non-terrestrial network, coverage information indicative of coverage of one or more terrestrial networks available to the UE, the coverage information comprising: a network identifier of the one or more terrestrial networks available to the UE; location information indicating a location of the UE; and a measure of signal strength of the one or more terrestrial networks available to the UE; and establishing one or more coverage areas of the one or more terrestrial networks based on the received coverage information. Again, by providing coverage information from UEs to an NTN, the NTN (or a server connected to the NTN) can calculate coverage information describing the coverage provided by the TNs. This can be used by the NTN or by some other entity in communication with the NTN to improve performance and efficiency in scenarios where UEs can connected to NTNs and TNs.

[0027] These and other advantages will become apparent from the following description. Listing of Figures

[0028] Embodiments of the disclosure will now be described by way of example and with reference to the accompanying drawings, in which:

[0029] Figure 1 shows a system for implementing methods of the disclosure;

[0030] Figure 2 shows a method of an embodiment of the disclosure;

[0031] Figure 3 shows a method of an embodiment of the disclosure; and Figure 4 shows a method of an embodiment of the disclosure.

[0032] Detailed Description

[0033] The present disclosure provides methods for allowing an NTN to obtain TN coverage information, which can be used to improve NTN to TN mobility. The disclosure provides a way of obtaining coverage information describing the coverage of one or more TNs in a given geographical area. Advantageously, some embodiments allow the operation of the TN not to be impacted while allowing the NTN to obtain the coverage information describing the coverage of the TN.

[0034] Figure 1 shows a system in which embodiments of the present disclosure can be implemented. More specifically, Figure 1 shows an example of a system for logging TN coverage information. The UEs in Figure 1 operate on TN neighbour cell measurements.

[0035] The system of Figure 1 includes a satellite 111 as part of an NTN. The coverage provided by the satellite 111 defines an NTN Cell. A plurality of TNs and associated base stations 101 , 102 and 103 are also shown. The coverage provided by the base stations 101 , 102 and 103 of the TNs define three TN cells: TN-Cell 1 ; TN-Cell 2; and TN-Cell 3. Two UEs 121 and 122 are shown, with the first UE 121 being in the coverage of TN-Cell 1 and the NTN Cell, with the second UE 122 being only in the coverage of NTN Cell. The first UE 121 may perform measurements on TN neighbour cells while connects to the NTN and may perform cell reselection between the NTN and the TN. The second UE 122 has no need to measure TN neighbour cells due to its position.

[0036] Figure 2 shows a flowchart of an embodiment of the present disclosure. In use, at least one of the UEs 121 , 122 in the system of Figure 1 performs, in generalised terms, a method comprising: measuring 201 , by a UE 121 , 122 connected to a non-terrestrial network, coverage information indicative of coverage of one or more terrestrial networks available to the UE 121 , 122. The coverage information comprises: a network identifier of the one or more terrestrial networks available to the UE 121 , 122; location information indicating a location of the UE 121 , 122; and a measure of signal strength of the one or more terrestrial networks available to the UE 121 , 122. The method further comprises a step of communicating 202, by the UE 121 , 122, the coverage information to the non-terrestrial network.

[0037] Figure 3 shows a flowchart of an embodiment of the present disclosure. In use, the NTN in Figure 1 may be described as performing, in generalised terms, a method comprising: receiving 301 , at a network entity of a non-terrestrial network and from a UE 121 , 122 connected to the non-terrestrial network, coverage information indicative of coverage of one or more terrestrial networks available to the UE 121 , 122. The coverage information comprises: a network identifier of the one or more terrestrial networks available to the UE 121 , 122; location information indicating a location of the UE 121 , 122; and a measure of signal strength of the one or more terrestrial networks available to the UE 121 , 122. The method further comprises establishing 302 one or more coverage areas of the one or more terrestrial networks based on the received coverage information.

[0038] The coverage information may comprise any one or more of a cell identifier of the one or more terrestrial networks; a Public Land Mobile Network (PLMN) identifier of the one or more terrestrial networks; a frequency of the one or more terrestrial networks; altitude information indicating an altitude of the UE; latitude and longitude information indicating a latitude and longitude of the UE; and a confidence interval (e.g., a confidence interval, such as standard deviation or some other measure, for any one or more of the location information, the frequency, the signal strength, and / or the altitude information).

[0039] The TN and the NTN can be any type of network. The non-terrestrial network is preferably a satellite network. The network entity may be a satellite base station or a server connected to (but which may be remote from) a satellite base station. The one or more terrestrial networks may comprise any one or more of a 3rd Generation Partnership Project (3GPP) network, a non-3GPP network, a New Radio (NR) network, a Long Term Evolution (LTE) network, a Universal Mobile Telecommunications System (UMTS) network, a Global System for Mobile Communications (GSM) network, a General Packet Radio Service (GPRS) network, and an Enhanced Data rates for GSM Evolution (EDGE) network or 6G network.

[0040] Measuring the coverage information may comprise the UE performing a measurement. For example, the UE may analyse the networks that are available to (i.e., visible) the UE and may determine a measure of signal strength (or some other parameter that parameterises the quality of the signal). The measure of signal strength may be a numerical value indicating the strength of the field received at the UE, although it could in some examples simply be a binary bit (i.e., a 0 or a 1 indicating whether the signal is above a certain threshold). The UE may measure coverage information indicative of coverage of a plurality of terrestrial networks (i.e., two or more) available to the UE. The step of communicating the coverage information to the non-terrestrial network may comprise sending the coverage information over the NTN. When the NTN (e.g., a server of the NTN or a server connected to the NTN) receives the coverage information, one or more coverage areas of the one or more terrestrial networks are established based on the received coverage information; this may involve analysing the coverage information to calculate a geographical area that is expected to be within range of the TNs associated with the coverage information.

[0041] In embodiments of the present disclosure, the NTN can obtain TN coverage information from the UEs while coverage is provided by the NTN. This may be advantageous because precise / accurate TN coverage boundaries cannot be predicted purely based on the layout of the network, for example due to the varying nature of the radio coverage (e.g., due to moving obstructions, or changes in weather) and the cell planning procedure (which may not be open to the public). Therefore, some embodiments of the present disclosure provide methods in which a UE, or a group of UEs, can be configured to provide information to the NTN network about TNs that are visible to the UE or group of UEs. Two examples of ways in which this can occur are:

[0042] > Method 1 : In cases where the TN coverage is assumed to be static in a given area, the TN information can be logged (i.e., stored) by one or more UEs and this logged information can be provided to the NTN network when requested or in a periodic manner.

[0043] > Method 2: The UE can be prompted to provide the visibility / TN coverage information immediately on request, but the UE may or may not otherwise log the TN coverage information. In Method 1 and / or Method 2, the coverage information may be measured periodically (i.e. repeatedly at a certain interval). The coverage information may be communicated periodically (with the same period as the period of measurement or with a different period) to the non-terrestrial network. The methods may comprise receiving, at the UE, a request for the coverage information over the non-terrestrial network and, in response to receiving the request for the coverage information, performing the step of measuring the coverage information and / or communicating the coverage information. Such a request could be sent periodically or non-periodically; for example, the request could be sent based on a determination that up-to-date coverage information is needed.

[0044] The TN coverage information provided by the UEs should provide a location, indicating a geographic location that is associated with the TN coverage information. For example, a location of the UE that performed the measurement can be provided. The information gathered over time by the NTN network can then be utilised to determine the TN coverage as a function of position. The TN coverage information can be broadcast by the NTN (for example, in an NTN SIB). An exemplary format for conveying coverage information in an NTN SIB is described in further detail below.

[0045] In generalised terms, the methods of the present disclosure may comprise communicating, to one or more UEs connected to the non-terrestrial network, data describing (e.g. the actual coverage data, or a processed version thereof) the one or more coverage areas in a system information block, SIB, of the non-terrestrial network. The methods may comprise determining, based on the established one or more coverage areas, a terrestrial network in range of the UE. The methods may involve communicating, to the UE and over the nonterrestrial network, an indication of the terrestrial network in range of the UE. Such an indication may be determined based on knowledge of the location of the UE. For example, the UE may communicate its current location or the NTN might know the UE’s current location from the NTN to which the UE is connected; then, based on the UE’s current location, the indication of a TN in range of the UE may be determined. This can allow the power usage of a UE to be reduced by providing the UE with information about TNs that are likely to be available.

[0046] TN coverage information can be logged in any UE state. For example, TN coverage information can be measured by a UE in any one or more of an IDLE mode, an INACTIVE state or a connected mode. The UE may perform the step of communicating the coverage information to the NTN in a connected mode. For logged TN coverage information, the configuration, measurement collection and reporting of the concerned coverage information will typically be performed in cells of the same RAT type, but this is not necessarily the case and different RAT types could be used.

[0047] An example of logged TN coverage information is shown in Figure 4.

[0048] The network (e.g., the NTN) may initiate the procedure of measuring coverage information. For example, the network may initiate the logging procedure for a UE in an RRC Connected mode by sending a Logged TN Coverage Configuration message, which can be used to transfer configuration parameters. This may be a unidirectional RRC signalling procedure.

[0049] The UE configured to measure TN coverage information may respond by indicating the availability of logged TN coverage information, for example by communicating a one bit flag during the RRC connection setup procedure message, RRC connection complete message or RRC resume complete procedure message. Such a flag can be used to inform the network of the availability of new logged data.

[0050] An indication that coverage information is available can be provided in a UElnformationResponse message during report retrieval. This can be performed, for example, if the UE has not transferred the total log in one RRC message (for example because only a partial log has been sent); in such a case, the indication that coverage information is available can be used to indicate the availability of the remaining data. In generalised terms, therefore, the coverage information may be communicated in a plurality of messages (e.g. partial logs), the coverage information being divided or split across the plurality of messages. Coverage information may be communicated in one or more (i.e. one or a plurality of) radio resource control (RRC) signalling messages

[0051] The network (e.g., the NTN) may decide to retrieve the logged TN coverage information based on receipt (e.g., from a UE) of an indication that coverage information is available (i.e., that coverage information has been obtained and is ready to be communicated to the NTN from the UE). If logged information is retrieved before the completion of a pre-defined logging duration (which may be some predetermined period of time, for example from 10 minutes or 30 minutes to 2 or 3 hours, or 1 hour, etc.), the procedure of TN coverage information logging may continue according to an ongoing logged measurement configuration.

[0052] If the NTN does not retrieve logged TN coverage information, the UE may store nonretrieved coverage information measurements for a certain duration of time (e.g. 48 hours, although other predetermined time periods could be used). The UE may store nonretrieved measurements for this duration from the moment a duration timer for logging expires. The UE may not be required to store non-retrieved data beyond the predefined duration. For example, the non-retrieved coverage information could be deleted after a certain time period. In addition or alternatively, all logged measurement configuration and the log may be removed from memory by the UE when the UE switches off or detaches from the network (the TN network and / or the NTN network). In generalised terms, the methods described herein may comprise storing coverage information in a memory of the UE for a predetermined time period (e.g. 48 hours). The UE may perform the step of communicating the coverage information to the non-terrestrial network during the predetermined time period. A timer may be provided.

[0053] In some cases, reporting of logged TN coverage information may be triggered by an on- demand mechanism. For example, the UE may be asked by the network to send the collected measurement logs via RRC signalling. The reporting may occur in different cells to the cells in which the logged measurement configuration is signalled. In some cases, reporting may occur in the same cell as the cell in which the logged measurement configuration is signalled, but this is not necessarily the case. The non-terrestrial network may request the logged information at any time and if the logged information is requested then it may subsequently be deleted from the UE. In generalised terms, the coverage information described herein may be measured for a plurality of different cells of the one or more terrestrial networks.

[0054] Logged TN coverage information reports may be communicated in multiple RRC messages. For example, with every request, the network may receive a part of a total UE log. To indicate that the reported data is a segment, the UE may include a data availability indicator in a UElnformatonResponse message to indicate that further measurement information is available. Detailed location information (e.g., Global Navigation Satellite System, GNSS, location information, such as Global Positioning System, GPS, or Global Navigation Satellite System, GLONASS) may be included if available in the UE when the measurement was taken. If detailed location information is available, the reporting will typically comprise a latitude and a longitude. Depending on availability, other information such as altitude, uncertainty and confidence may also be included. The UE may tag available detailed location information only once with an upcoming measurement sample, and then the detailed location information may be discarded, i.e., the validity of detailed location information may implicitly be assumed to be one logging interval. In some cases (for example where location information is not readily available), other information or measurements that can be used to derive location information could be provided as part of the coverage information. For instance, if GNSS is not available, then signal strengths and identifiers of base stations could be used for triangulation, or could be communicated to the NTN to facilitate subsequent triangulation.

[0055] Embodiments described herein allow UEs to be provided with information about TNs that are potentially in range. It can be advantageous for a UE to know if it is (potentially) in range of a TN to start measurements. Without being provided with this information in advance, a UE would need to perform measurements on TN frequencies to identify TNs that are in range. However, if the UE has already been provided with TN coverage information, then the UE may only perform the measurements when it is located in or close to the TN coverage area. Hence, the methods described herein can reduce power consumption and improve battery life of the UE, by reducing unnecessary measurements.

[0056] For instance, returning to the generalised terms used previously, some embodiments of the present disclosure involve: receiving, over the non-terrestrial network, an indication of one or more terrestrial networks in range of the first UE and / or a second UE connected to the non-terrestrial network; and in response to receiving the indication, handing over, by the first UE and / or the second UE, from the non-terrestrial network to one of the one or more terrestrial networks in range of the first UE and / or the second UE. For example, the same UE that provides the coverage information to the NTN may subsequently perform a handover to TN based on an indication received from the NTN, or a different UE connected to the NTN may subsequently perform a handover to TN based on an indication received from the NTN. For example, if measurement and / or searching for TNs indicate that a TN is in range, then the UE may perform a handover from the NTN to the TN. Accordingly, the present disclosure can reduce power consumption of a plurality of different UEs. The indication of one or more terrestrial networks in range may include any one or more of a TN identifier, a geographic area, a radius, a centre location, etc. Based on receiving such information, one or more UEs can make informed decisions to handover to the TN since the one or more UEs will know that the TN should be in range. Thus, the coverage information provided by the NTN to the UE can be used to allow UEs to make intelligent handover decisions.

[0057] The skilled person will appreciate that before initiating a handover, a UE may perform measurements on the available TN network(s). Hence, in some embodiments, there may be an extra intermediate step or extra intermediate steps between receiving an indication of one or more terrestrial networks in range of the first UE and / or the second UE. For example, the intermediate step(s) could include a step of: searching, by the first UE and / or the second UE, for the one or more terrestrial networks in range of the first UE and / or the second UE; and / or searching, by the first UE and / or the second UE, at the one or more frequencies (or in the frequency bands) associated with the one or more respective terrestrial networks in range of the first UE and / or the second UE.

[0058] The methods described herein may involve: in response to receiving the indication of one or more terrestrial networks in range of the first UE and / or a second UE connected to the non-terrestrial network, searching, by the first UE and / or the second UE, for the one or more terrestrial networks in range of the first UE and / or the second UE. This can prevent the first UE and / or the second UE searching for TNs unnecessarily. Searching may involve, for example, performing UE measurement, or measuring link quality (which could be used to decide whether to perform a handover, or which could be communicated to the NTN as part of the coverage information communicated thereto). It should be noted that there may be more than just the first and second UEs; rather, there may be a plurality of UEs. Then, one of the plurality of UEs may perform searching, by one of the plurality of UEs, for the one or more terrestrial networks in range of the one of the plurality of UEs.

[0059] Moreover, further advantages can be realised by relaxing measurements on TN frequencies based on the TN coverage information. Without TN coverage information, cell reselection will be performed based on frequency priorities. A TN frequency is likely to have a reselection priority higher than the reselection priority of current NTN frequency. Thus, even when there is no TN coverage, the UE will search at the frequency of the TN, hence wasting battery. Accordingly, providing the UE with coverage information can help to reduce measurements or to avoid the UE attempting to perform unnecessary measurements.

[0060] Hence, in some embodiments, the methods described herein may comprise: receiving, over the non-terrestrial network, an indication of one or more frequencies (e.g. one or more frequency bands) associated with one or more respective terrestrial networks (i.e., each terrestrial network may be associated with a respective one or more frequencies, e.g., there may be one or more frequency bands per TN) in range of the first UE and / or a second UE connected to the non-terrestrial network; and in response to receiving the indication, searching, by the first UE and / or the second UE, at the one or more frequencies (or in the frequency bands) associated with the one or more respective terrestrial networks in range of the first UE and / or the second UE. In this way, a UE may not need to scan such a wide range of frequencies to identify a TN that is in range; the UE can perform more selective searching, by only searching for TNs that have been indicated as being in range of the UE. It should be noted again that there may be more than just the first and second UEs; rather, there may be a plurality of UEs. Then, one of the plurality of UEs may perform the step of searching, at the one or more frequencies (or in the frequency bands) associated with the one or more respective terrestrial networks in range of the one of the plurality of UEs.

[0061] As noted previously, the TN coverage information provided by the UE to the NTN network may contain location information. The geographical area information for TN coverage can be provided with location coordinates of an area centre and a radius using Ellipsoid-Point and radius, or other geographical co-ordinates in terms of longitude and latitude. The TN coverage information may be provided by the network via a list of (possibly overlapping) areas, where each area is defined using a centre location coordinates and a radius. The area represents a group of cells. The area’s centre location and its radius for TN coverage information may be signalled using Ellipsoid-Point and radius separately, using the same format of Release-17 (Rel-17) referenceLocation and distanceThresh for signalling the TN coverage area centre and radius.

[0062] An example based on TS 38.331 is shown below: [distanceThresh- r17 INTEGER(0..65525) OPTIONAL, - Need R distanceThresh

[0063] Distance from the serving cell reference location and is used in location-based measurement initiation in RRCJDLE and RRCJNACTIVE, as defined in TS 38.304

[0020] . Each step represents 50m.

[0064] Reference Location

[0065] The IE ReferenceLocation contains location information used as a reference location. The value of the field is same as Ellipsoid-Point defined in TS37.355

[0049] . The first / leftmost bit of the first octet contains the most significant bit.

[0066] ReferenceLocation information element

[0067] - ASN1 START

[0068] - TAG-REFERENCELOCATION-START

[0069] ReferenceLocation-r17 ::= OCTET STRING

[0070] - TAG-REFERENCELOCATION-STOP

[0071] - ASN1STOP

[0072] Other information can be provided as part of the coverage information. For example, the coverage information may comprise: PLMN-ldentitylnfo in PLMN-ldentitylnfoList, the frequency information for the TN coverage area (likely to be indicated as a pointer to frequency information in SIB4 and SIB5) and / or Cell identity.

[0073] Although specific embodiments have been described, the skilled person will understand that various modifications and variations are possible. For example, whilst the disclosure is described in relation to existing network architecture, it will be understood that changes to the architecture (and / or nomenclature) are possible, but the present disclosure may still be applicable in this case. Also, combinations of any specific features shown with reference to one embodiment or with reference to multiple embodiments are also provided, even if that combination has not been explicitly detailed herein. A base station may be referred to as a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), a Node B (NB), an eNode B (eNB), a gNode B (gNB), a transmission and reception point (TRP), or some other suitable terminology, depending on the protocol, standard, context or technology. In some examples, a base station may include two or more transceivers that may or may not be collocated. Each transceiver may communicate on the same or different carrier frequency within the same or different frequency band. The NTNs and TNs described herein may operate on the same or different frequency bands.

[0074] Where the disclosure refers to a server or network entity, for instance, this may actually be a pair of servers, or network entities (primary and failover), for redundancy.

[0075] In this disclosure, the word “communicating” may mean “sending”, “receiving”, or “sending and / or receiving”, depending on the context.

[0076] The methods, techniques, apparatuses, and systems described herein may be applied to a variety of wireless systems. Examples of the systems that can be used in the present disclosure include 5Gcore with 5G-NR; a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, a single carrier frequency division multiple access (SC-FDMA) system, and a multicarrier frequency division multiple access (MC-FDMA) system. CDMA may be embodied through radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be embodied through radio technology such as global system for mobile communications (GSM), general packet radio service (GPRS), or enhanced data rates for GSM evolution (EDGE). OFDMA may be embodied through radio technology such as institute of electrical and electronics engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or evolved UTRA (E-UTRA). UTRA is a part of a universal mobile telecommunications system (UMTS). 3rdgeneration partnership project (3GPP) long term evolution (LTE) is a part of evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA in DL and SC- FDMA in UL. LTE-advanced (LTE-A) is an evolved version of 3GPP LTE. Embodiments of the present disclosure may be applied to 3GPP LTE / LTE-A. For example, although the foregoing detailed description is given based on a mobile communication system corresponding to an NTN (E-)UTRAN or NR system, aspects of the present disclosure that are not specific to NTN (E-)UTRAN or NR are applicable to other mobile communication systems including future mobile communication systems (e.g. 6G).

[0077] In the present disclosure, a user equipment (UE) may be a fixed or mobile device. Examples of the UE include various devices that transmit and receive user data and / or various kinds of control information to and from a base station (BS). The UE may be referred to as a terminal equipment (TE), a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, a personal digital assistant (PDA), a wireless modem, a handheld device, etc. In addition, in the present disclosure, a BS generally refers to a fixed station that performs communication with a UE and / or another BS, and exchanges various kinds of data and control information with the UE and another BS. The BS may be referred to as an advanced base station (ABS), a node-B (NB), an evolved node-B (eNB), a gNB, a base transceiver system (BTS), an access point (AP), a processing server (PS), etc.

[0078] In the present disclosure, a node refers to a fixed point capable of transmitting / receiving a radio signal through communication with a UE. Various types of eNBs may be used as nodes irrespective of the terms thereof. For example, a BS, a node B (NB), an e-node B (eNB), a g-node B (gNB), a relay, a repeater, etc. may be a node.

[0079] In the present invention, a cell refers to a geographical area to which one or more nodes provide a communication service. Where a non-terrestrial (e.g., satellite) network provides connectivity, the cell may move together with the network entity. Accordingly, in the present invention, communicating with a specific cell may mean communicating with a gNB or a node that provides a communication service to the specific cell. Furthermore, channel status / quality of a specific cell refers to channel status / quality of a channel or communication link formed between an gNB or node which provides a communication service to the specific cell and a UE. The UE may measure DL channel state received from a specific node using cell-specific reference signal(s) (CRS(s)) transmitted on a CRS resource and / or channel state information reference signal(s) (CSI-RS(s)) transmitted on a CSI-RS resource, allocated by antenna port(s) of the specific node to the specific node. Meanwhile, a 3GPP system uses the concept of a cell in order to manage radio resources and a cell associated with the radio resources is distinguished from a cell of a geographic region. The examples may be carried out on any suitable data processing device, such as a personal computer, laptop, mobile telephone, server, virtual machine, and the like. The above description of the systems and methods has been simplified for purposes of discussion and is intended to provide a specific example to illustrate the invention. Different types of systems and methods may be used, as will be appreciated by the skilled person. It will be appreciated that the boundaries between logic blocks are merely illustrative and that alternative embodiments may merge logic blocks or elements, or may impose an alternate decomposition of functionality upon various logic blocks or elements.

[0080] It will be appreciated that the above-mentioned functionality may be implemented as one or more corresponding modules as hardware and / or software. For example, the above- mentioned functionality may be implemented as one or more software components for execution by a processor of the system. Alternatively, the above-mentioned functionality may be implemented as hardware, such as on one or more field-programmable-gate-arrays (FPGAs), and / or one or more application-specific-integrated-circuits (ASICs), and / or one or more digital-signal-processors (DSPs), and / or other hardware arrangements. Method steps implemented in flowcharts contained herein, or as described above, may each be implemented by corresponding respective modules. Moreover, multiple method steps implemented in flowcharts contained herein, or as described above, may be implemented together by a single module.

[0081] Examples may be implemented by computer software or a “computer program”. A storage medium and a transmission medium carrying the computer software are also provided. The computer software may comprise one or more instructions, or code, that, when executed by a computer, causes the methods described to be performed. Computer software may be a sequence of instructions designed for execution on a computer system, and may include a subroutine, a function, a procedure, a module, an object method, an object implementation, an executable application, an applet, a servlet, source code, object code, a shared library, a dynamic linked library, and / or other sequences of instructions designed for execution on a computer system. The storage medium may be a magnetic disc (such as a hard drive or a floppy disc), an optical disc (such as a CD-ROM, a DVD-ROM or a BluRay disc), or a memory (such as a ROM, a RAM, EEPROM, EPROM, Flash memory or a portable / removable memory device), etc. The transmission medium may be a communications signal, a data broadcast, a communications link between two or more computers, etc. Each feature disclosed in this specification, unless stated otherwise, may be replaced by alternative features serving the same, equivalent or similar purpose. Thus, unless stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0082] As used herein, including in the claims, unless the context indicates otherwise, singular forms of the terms herein are to be construed as including the plural form and vice versa. For instance, unless the context indicates otherwise, a singular reference herein including in the claims, such as “a” or “an” (such as a UE, a network entity, or a cell) means “one or more” (for instance one or more UEs, one or more network entities, or one or more cells). Throughout the description and claims of this disclosure, the words “comprise”, “including”, “having” and “contain” and variations of the words, for example “comprising” and “comprises” or similar, mean “including”, and are not intended to (and do not) exclude other components.

[0083] The use of any and all examples, or exemplary language (“for instance”, “such as”, “for example” and like language) provided herein, is intended merely to better illustrate the invention and does not indicate a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any nonclaimed element as essential to the practice of the invention.

[0084] Any steps described in this specification may be performed in any order or simultaneously unless stated or the context requires otherwise. Moreover, where a step is described as being performed after a step, this does not preclude intervening steps being performed.

[0085] All of the aspects and / or features disclosed in this specification may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. In particular, the preferred features of the invention are applicable to all aspects of the invention and may be used in any combination. Likewise, features described in non-essential combinations may be used separately (not in combination).

[0086] A method of manufacturing and / or operating any of the devices disclosed herein is also provided. The method may comprise steps of providing each of the features disclosed and / or configuring or using the respective feature for its stated function.

Claims

Claims:

1. A method comprising: measuring, by a user equipment, UE, connected to a non-terrestrial network, coverage information indicative of coverage of one or more terrestrial networks available to the UE, the coverage information comprising: a network identifier of the one or more terrestrial networks available to the UE; location information indicating a location of the UE; and a measure of signal strength of the one or more terrestrial networks available to the UE; and communicating, by the UE, the coverage information to the non-terrestrial network.

2. The method of claim 1 , wherein the UE is a first UE, the method further comprising: receiving, over the non-terrestrial network, an indication of one or more terrestrial networks that are in range of the first UE and / or a second UE connected to the nonterrestrial network.

3. The method of claim 2, further comprising: in response to receiving the indication, searching, by the first UE and / or the second UE, for the one or more terrestrial networks that are in range of the first UE and / or the second UE; and / or in response to receiving the indication, searching, by the first UE and / or the second UE, at the one or more frequencies associated with the one or more respective terrestrial networks that are in range of the first UE and / or the second UE.

4. The method of claim 3, further comprising handing over, by the first UE and / or the second UE, from the non-terrestrial network to one of the one or more terrestrial networks that are in range of the first UE and / or the second UE.

5. The method of any preceding claim, comprising measuring the coverage information for a plurality of different cells of the one or more terrestrial networks.

6. The method of any preceding claim, comprising periodically measuring, by the UE, the coverage information.

7. The method of any preceding claim, comprising periodically communicating, by the UE, the coverage information to the non-terrestrial network.

8. The method of any preceding claim, further comprising receiving, at the UE, a request for the coverage information over the non-terrestrial network and, in response to receiving the request for the coverage information, performing the step of measuring the coverage information and / or communicating the coverage information.

9. The method of any preceding claim, wherein: the UE performs the step of measuring the coverage information in any one or more of: an IDLE mode; an INACTIVE mode; or a connected mode; and / or the UE performs the step of communicating the coverage information in a connected mode.

10. The method of any preceding claim, further comprising storing the coverage information in a memory of the UE for a predetermined time period.11 . The method of claim 10, wherein the UE performs the step of communicating the coverage information to the non-terrestrial network during the predetermined time period.

12. A method comprising: receiving, at a network entity of a non-terrestrial network and from a user equipment, UE, connected to the non-terrestrial network, coverage information indicative of coverage of one or more terrestrial networks available to the UE, the coverage information comprising: a network identifier of the one or more terrestrial networks available to the UE; location information indicating a location of the UE; and a measure of signal strength of the one or more terrestrial networks available to the UE; and establishing one or more coverage areas of the one or more terrestrial networks based on the received coverage information.

13. The method of claim 12, further comprising communicating, to one or more UEs connected to the non-terrestrial network, data describing the one or more coverage areas in a system information block, SIB, of the non-terrestrial network.

14. The method of claim 12 or claim 13, further comprising determining, based on the established one or more coverage areas, one or more terrestrial networks that are in range of the UE.

15. The method of claim 14, further comprising communicating, to the UE and over the non-terrestrial network, an indication of the one or more terrestrial networks that are in range of the UE.

16. The method of any preceding claim, wherein the coverage information comprises any one or more of: a cell identifier of the one or more terrestrial networks; a Public Land Mobile Network, PLMN, identifier of the one or more terrestrial networks; a frequency of the one or more terrestrial networks; altitude information indicating an altitude of the UE; latitude and longitude information indicating a latitude and longitude of the UE; and a confidence interval.

17. The method of any preceding claim, wherein: the non-terrestrial network is a satellite network; and / or the one or more terrestrial networks comprise any one or more of a 3rd Generation Partnership Project (3GPP) network, a non-3GPP network, a New Radio (NR) network, a Long Term Evolution (LTE) network, a Universal Mobile Telecommunications System (UMTS) network, a Global System for Mobile Communications (GSM) network, a General Packet Radio Service (GPRS) network, an Enhanced Data rates for GSM Evolution (EDGE) network, and a 6th Generation Network.

18. The method of any preceding claim, wherein the coverage information is communicated in a plurality of messages, the coverage information being divided across the plurality of messages.

19. The method of any preceding claim, wherein the coverage information is communicated in one or more radio resource control (RRC) signalling messages.

20. One or more user equipment, UEs, configured to perform the method of any of claims 1 to 11.21 . A network entity configured to perform the method of any of claims 12 to 19.

22. The network entity of claim 21 , wherein the network entity is a satellite base station or a server connected to a satellite base station.

23. A telecommunications network comprising the UE of claim 20 and / or the network entity of claim 21 or claim 22.

24. A computer program product comprising instructions that, when executed on a processor, cause the processor to perform the method of any of claims 1 to 19.

25. A computer-readable medium having stored thereon the computer program of claim

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