A method in a wireless telecommunications network

Abstract

This invention provides a method in a wireless telecommunications network, the wireless telecommunications network comprising: one or more gateways; a plurality of Reconfigurable Intelligent Surfaces, RISs; and a plurality of non-terrestrial access points; the method comprising the steps of: detecting a trigger to develop a connection in the wireless telecommunications network; obtaining data identifying a requirement for a performance parameter of the connection; obtaining data for a first candidate connection comprising at least two inter-non-terrestrial access point connections via a respective RIS of the plurality of RIS, the data identifying a first value of the performance parameter for the first candidate connection; comparing the first value of the performance parameter for the first candidate connection to the requirement for the performance parameter of the connection; and based on the comparison, developing the connection.

Description

[0001] A METHOD IN A WIRELESS TELECOMMUNICATIONS NETWORK

[0002] Field of the Invention

[0003] The present invention relates to a method in a wireless telecommunications network.

[0004] Background

[0005] Wireless telecommunications networks typically comprise a terrestrial access point (e.g. base station) communicating with terrestrial User Equipment (UE). The term NonTerrestrial Network (NTN) covers any network that comprises an aerial vehicle, and includes satellite communication networks, High Altitude Platform (HAP) networks, air- to-ground networks, and low-altitude Unmanned Aerial Vehicles (UAVs). The aerial vehicles, such as a satellite, HAP vehicle (e.g. airplane, balloon, airship, etc.) or UAV may comprise an access point (a “non-terrestrial access point”). Figure 1 illustrates an example NTN, comprising a core network, a terrestrial base station, a gateway, a nonterrestrial access point, and a UE. The core network and terrestrial base station may be connected, for example, by an NG interface. The base station may connect to the gateway which provides a feeder link to the non-terrestrial access point. The nonterrestrial access point connects to the UE via a service link, for example, by a NR-Uu interface. User plane and control plane traffic may therefore be communicated between the UE and core network via the NG interface, feeder link and service link.

[0006] The NTN 100 further comprises a control station 140 and command and control centre 150. The command and control centre 150 is configured to communicate with each of the plurality of non-terrestrial access points 130, via the control station 130, using a command and control (“C2”) link. The C2 link is a highly reliable link, separate to the feeder link, used to communicate, for example, telecommands, telemetry and air traffic control communications.

[0007] In an NTN comprising a plurality of non-terrestrial access points, it is desirable to provide an inter-non-terrestrial-access point connection. These connections may utilise free- space-optics or active phase-array antennas, requiring each aerial vehicle to comprise dedicated communication equipment (in addition to the wireless telecommunications equipment used for the feeder and service links). This additional equipment adds weight to the aerial vehicle, which reduces its mission time (that is, the time the aerial vehicle is airborne). Summary of the Invention

[0008] According to a first aspect of the invention, there is provided a method in a wireless telecommunications network, the wireless telecommunications network comprising: one or more gateways; a plurality of Reconfigurable Intelligent Surfaces, RISs; and a plurality of non-terrestrial access points; the method comprising the steps of: detecting a trigger to develop a connection in the wireless telecommunications network; obtaining data identifying a requirement for a performance parameter of the connection; obtaining data for a first candidate connection comprising at least two inter-non-terrestrial access point connections via a respective RIS of the plurality of RIS, the data identifying a first value of the performance parameter for the first candidate connection ; comparing the first value of the performance parameter for the first candidate connection to the requirement for the performance parameter of the connection; and based on the comparison, developing the connection.

[0009] The comparison step may indicate that the first value of the performance parameter for the first candidate connection meets the requirement for the performance parameter of the connection.

[0010] The method may further comprise the steps of: obtaining data for a second candidate connection comprising at least two inter-non-terrestrial access point connections via a respective RIS of the plurality of RIS, the data identifying a first value of the performance parameter for the second candidate connection; comparing the first value of the performance parameter for the second candidate connection to the requirement for the performance parameter for the connection, wherein both the first value of the performance parameter for the first candidate connection and the first value of the performance parameter for the second candidate connection meet the requirement for the performance parameter of the connection; selecting one of the first and second candidate connections, wherein the step of developing the connection uses the selected first or second candidate connection.

[0011] The method may further comprise the step of: identifying a candidate reconfiguration of the wireless telecommunications network, wherein the first candidate connection may be based on the wireless telecommunications network as reconfigured in the candidate reconfiguration. The method may further comprise the step of: identifying one or more candidate reconfigurations of the wireless telecommunications network, wherein the first and second candidate connections are based on the wireless telecommunications network as reconfigured in one or more of the candidate reconfigurations.

[0012] The connection may be developed in response to one or more of a group comprising: a new non-terrestrial access point connecting to the wireless telecommunications network, and a new User Equipment, UE, connection being established in the wireless telecommunications network.

[0013] According to a second aspect of the invention, there is provided a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the method of the first aspect of the invention. The computer program may be stored on a computer readable carrier medium.

[0014] Brief Description of the Figures

[0015] In order that the present invention may be better understood, embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings in which:

[0016] Figure 1 is a schematic diagram of a conventional non-terrestrial wireless telecommunications network;

[0017] Figure 2 is a schematic diagram of a first non-terrestrial wireless telecommunications network;

[0018] Figure 3 is a schematic diagram of a second non-terrestrial wireless telecommunications network; and

[0019] Figure 4 is a flow diagram illustrating a method.

[0020] Detailed Description

[0021] Figure 2 illustrates a first Non-Terrestrial Network (NTN) 100. The first NTN 100 is based on a 3rdGeneration Partnership Project (3GPP) 5thGeneration protocol and comprises a core network 110, a gateway 120, a plurality of non-terrestrial access points 130 and a User Equipment (UE). In this example, the non-terrestrial access points 130 are each part of a High-Altitude Platform (HAP), such as an airplane, balloon or airship. The gateway 120 is configured to provide a feeder link to one or more of the plurality of non-terrestrial access points. In the example of Figure 2, the gateway 120 provides a feeder link to the first non-terrestrial access point 130a. The first NTN 100 may comprise one or more terrestrial access points (not shown), which may communicate with the nonterrestrial access points (and any UE connected thereto) via the gateway 120 and feeder link.

[0022] The first NTN 100 further comprises a control station 140 and command and control centre 150. The command and control centre 150 is configured to communicate with each of the plurality of non-terrestrial access points 130, via the control station 140, using a command and control (“C2”) link. The C2 link is a connection for communicating, for example, telecommands, telemetry and air traffic control communications. This C2 link is highly reliable and separate to the feeder link. Using this data, the command and control centre 150 continuously monitors and controls the flight plan of each HAP.

[0023] The first NTN 100 further comprises a plurality of Reconfigurable Intelligent Surfaces (RISs) 160 and a controller 170. The RISs are described in more detail below. The controller 170 is connected to each RIS 160 and is configured to send configuration messages to each RIS 160. The controller 170 is further connected to each nonterrestrial access point 130, via the C2 link, and is configured to send configuration messages to each non-terrestrial access point 130.

[0024] A first non-terrestrial access point 130a is configured to form a service link with the UE using a Uu interface and is further configured to form a feeder link with the gateway 120. In this example, a second non-terrestrial access point 130b is unable to form a direct feeder link with gateway 120. This is addressed by forming an indirect feeder link with the gateway via the first non-terrestrial access point 130a. That is, an indirect feeder link is formed as a first connection between the second non-terrestrial access point 130b and first non-terrestrial access point 130a and a second connection being the direct feeder link between the first non-terrestrial access point 130a and the gateway. All control plane and user plane data (excluding any C2 data) communicated with the second nonterrestrial access point 130b (and any UE connected to the second non-terrestrial access point 130b) may therefore use this indirect feeder link with the gateway 120. The first non-terrestrial access point 130a is therefore configured to relay any control plane and user plane traffic that is associated with the second non-terrestrial access point 130b via the first connection between the first and second non-terrestrial access points 130a, 130b. As will now be described in more detail, this first connection between the first and second non-terrestrial access points 130a, 130b is based on a reflection via a RIS (a second RIS 160b in Figure 2) of the plurality of RIS 160.

[0025] A RIS 160 of the plurality of RIS 160 will now be described in more detail. Each RIS 160 may be an inexpensive adaptive thin composite material sheet and is capable of modifying radio waves impinging upon it, or passing through it, in ways that can be programmed and controlled by using external stimuli. This technology has been described by a wide variety of names including: large intelligent surfaces, reconfigurable reflectarrays, reconfigurable intelligent surfaces, intelligent reflecting surfaces, software- controlled metasurfaces, and programmable surfaces. Each RIS 160 can operate in reflection and may comprise an array of reflecting unit cells (e.g. diode-controlled unit cells). The unit cell separation determines the electromagnetic frequency of operation and the controller 170 determines the reflective characteristics of the surface. Generally, a RIS 160 operates to produce a change in the electromagnetic waves incident on the RIS unit cell.

[0026] In the first NTN 100, the second RIS 160b is configured to reflect a signal communicated between the first and second non-terrestrial access point 130a, 130b as part of the first connection between the first and second non-terrestrial access points 130a, 130b. A suitable reflection of these signals may be achieved by configuring the unit cells of the second RIS 160b. This configuration may utilise data regarding a location of each nonterrestrial access point, which may be received at the controller 170 from the command and control centre 150, to determine a configuration of each unit cell of the second RIS 160b for reflecting signals between the first and second non-terrestrial access point 130a, 130b. Alternatively, the second RIS 160b may be configured by a calibration phase in which a plurality of candidate configurations of the second RIS 160b are tested and the resulting performance of the first connection between the first and second nonterrestrial access points 10a, 130b is measured, with the best performing candidate configuration being selected. The second RIS 160b may be reconfigured to accommodate for any changes in the first connection, such as a change in relative position of the first and second non-terrestrial access points 130a, 130b. A signal communicated as part of the inter-non-terrestrial access point connection via the RIS 160 may be a service link signal (that is, having the same form as a service link signal between a non-terrestrial access point and a UE). Alternatively, the signal communications as part of the inter-non-terrestrial access point connection differs from the service link signal (e.g. uses different spectrum and / or radio equipment) but shares at least some of the equipment used for the service link signal. The same equipment for forming the non-terrestrial access point and UE connection may therefore be additionally used for forming the inter-non-terrestrial access point connection, such that additional equipment (e.g. free-space-optics equipment) is not required for the inter-non-terrestrial access point connection. This decreases weight of the HAP, and therefore increases mission time.

[0027] The RIS 160 may also be divided into a plurality of subarrays, each subarray comprising a subset of the reflecting unit cells of the array of reflecting unit cells. Each subarray may be controlled to independently reflect a signal between non-terrestrial access points, such that the reflection of a signal between a first set of non-terrestrial access points by a first subarray of the RIS 160 is independent of the reflection of a signal between a second set of non-terrestrial access points by a second subarray of the RIS 160. The controller 170 may therefore be configured to control each subarray of the RIS 160 to reflect signals between non-terrestrial access points. Furthermore, the controller 170 may reconfigure the composition of each subarray, such as by determining a count of reflecting unit cells of each subarray and / or which reflecting unit cells should form each subarray. Details of the formation and use of subarrays of a RIS can be found, for example, in “A Dynamic Subarray Structure in Reconfigurable Intelligent Surfaces for TeraHertz Communication Systems”, Liu et al, https: / / arxiv.org / abs / 2206.14968.

[0028] In the following description, the term “cluster” will be used to define a set of non-terrestrial access points that share a common feeder link. The cluster therefore comprises at least one non-terrestrial access point having a direct feeder link (hereinafter, the “primary nonterrestrial access point”), and may comprise one or more non-terrestrial access points having an indirect feeder link (hereinafter, the “secondary non-terrestrial access point”). A non-terrestrial access point may be a member of multiple clusters. Furthermore, there may be one or more RIS in each cluster, and a RIS may be utilised in connections between non-terrestrial access points of different clusters. A second NTN 200 is illustrated in Figure 3. The second NTN 200 comprises a core network 210, a gateway 220, a plurality of non-terrestrial access points 230, a control station 240, a command and control centre 250, a plurality of RIS 260, and a controller 270. The second NTN 200 may also comprise one or more terrestrial base stations (not shown). The plurality of non-terrestrial access points 230 includes a primary nonterrestrial access point 230a that has a direct connection with the gateway 220, a first secondary non-terrestrial access point 230b that has an indirect connection with the gateway 220, a second secondary non-terrestrial access point 230c that also has an indirect connection with the gateway 220, and a third secondary non-terrestrial access point 230d that also has an indirect connection with the gateway 220. The following is noted regarding the indirection connections:

[0029] • the indirect connection of the first secondary non-terrestrial access point 230b comprises the direct connection between the gateway 220 and the primary nonterrestrial access point 230a and an inter-non-terrestrial access point connection between the primary and first secondary non-terrestrial access points via a first RIS 260a of the plurality of RIS 260;

[0030] • the indirect connection of the second secondary non-terrestrial access point 230c comprises the direct connection between the gateway 220 and the primary nonterrestrial access point 230a, the inter-non-terrestrial access point connection between the primary and first secondary non-terrestrial access points 230a, 230b via the first RIS 260a, and an inter-non-terrestrial access point connection between the first and second secondary non-terrestrial access points 230b, 230c via a second RIS 260b of the plurality of RIS 260; and

[0031] • the indirect connection of the third secondary non-terrestrial access point 230d comprises the direct connection between the gateway 220 and the primary nonterrestrial access point 230a, the inter-non-terrestrial access point connection between the primary and first secondary non-terrestrial access points 230a, 230b via the first RIS 260a, the inter-non-terrestrial access point connection between the first and second secondary non-terrestrial access points 230b, 230c via the second RIS 260b, and an inter-non-terrestrial access point connection between the second and third secondary non-terrestrial access points 230c, 230d via a third RIS 260c of the plurality of RIS.

[0032] The indirect connection of the second secondary non-terrestrial access point 230c and the indirect connection of the third secondary non-terrestrial access point 230d are therefore multi-hop inter-non-terrestrial access point connections as they each comprise more than one inter-non-terrestrial access point connection.

[0033] The second NTN 200 further comprises a fifth non-terrestrial access point 230e, which will be discussed in more detail below.

[0034] A method will now be described with reference to Figure 4. In a first step (S101 ), the controller 270 detects a trigger for developing a connection (e.g. creating a new connection or reconfiguring an existing connection) that utilises a multi-hop inter-non- terrestrial access point connection. For example, the controller 270 may detect the fifth non-terrestrial access point 230e that requires a new multi-hop inter-non-terrestrial access point connection to the gateway 220, or the controller 270 may detect a new service link via an existing multi-hop inter-non-terrestrial access point connection with the gateway 220. The following description relates to the scenario in which the controller 270 detects the fifth non-terrestrial access point 230e that requires a new connection to the gateway 220.

[0035] In step S103, the controller 270 determines one or more performance requirements of the connection to be established between the gateway 220 and the fifth non-terrestrial access point 230e. The one or more performance requirements may be for one or more communication properties of the indirect connection, such as received power and latency. These one or more performance requirements may be obtained from the command and control centre 250 and / or from another gateway that previously served the fifth non-terrestrial access point 230e. In the following description, the fifth nonterrestrial access point 230e has a latency requirement.

[0036] In step S105, the controller 270 identifies each candidate connection between the gateway 220 and the fifth non-terrestrial access point 230e. These candidate connections include all possible inter-non-terrestrial access point connections via any RIS of the plurality of RIS 260 (and any subarray of each RIS). The identified candidate connections include, inter alia:

[0037] • a first candidate connection as a direct connection between the gateway 220 and the fifth non-terrestrial access point 230e;

[0038] • a second candidate connection comprising the direct connection between the gateway 220 and the primary non-terrestrial access point 230a and an inter-non- terrestrial access point connection between the primary non-terrestrial access point 230a and the fifth non-terrestrial access point 230e via the first RIS 260a;

[0039] • a third candidate connection comprising the direct connection between the gateway 220 and the primary non-terrestrial access point 230a, the inter-non- terrestrial access point connection between the primary and first secondary nonterrestrial access points 230a, 230b via the first RIS 260a, and an inter-non- terrestrial access point connection between the first secondary non-terrestrial access point 230b and the fifth non-terrestrial access point 230e via the second RIS 260b;

[0040] • a fourth candidate connection comprising the direct connection between the gateway 220 and the primary non-terrestrial access point 230a, the inter-non- terrestrial access point connection between the primary and first secondary nonterrestrial access points 230a, 230b via the first RIS 260a, the inter-non-terrestrial access point connection between the first and second secondary non-terrestrial access points 230b, 230c via the second RIS 260b, and an inter-non-terrestrial access point connection between the second secondary non-terrestrial access point 230c and the fifth non-terrestrial access point 230e via the third RIS 260c;

[0041] • a fifth candidate connection comprising the direct connection between the gateway 220 and the primary non-terrestrial access point 230a, the inter-non- terrestrial access point connection between the primary and first secondary nonterrestrial access points 230a, 230b via the first RIS 260a, the inter-non-terrestrial access point connection between the first and second secondary non-terrestrial access points 230b, 230c via a first subarray of the second RIS 260b, and an inter-non-terrestrial access point connection between the second secondary nonterrestrial access point 230c and the fifth non-terrestrial access point 230e via a second subarray of the second RIS 260b;

[0042] • a sixth candidate connection comprising the direct connection between the gateway 220 and the primary non-terrestrial access point 230a, the inter-non- terrestrial access point connection between the primary and first secondary nonterrestrial access points 230a, 230b via the first RIS 260a, the inter-non-terrestrial access point connection between the first and second secondary non-terrestrial access points 230b, 230c via the second RIS 260b, the inter-non-terrestrial access point connection between the second and third secondary non-terrestrial access point 230c, 230d via a first subarray of the third RIS 260c, and an inter- non-terrestrial access point connection between the third secondary non- terrestrial access point 230d and the fifth non-terrestrial access point 230e via a second subarray of the third RIS 260c; and

[0043] • a seventh candidate connection comprising the direct connection between the gateway 220 and the primary non-terrestrial access point 230a, an inter-non- terrestrial access point connection between the primary and second secondary non-terrestrial access points 230a, 230c via the second RIS 260b, and an inter- non-terrestrial access point connection between the second secondary nonterrestrial access point 230c and the fifth non-terrestrial access point 230e via the third RIS 260c.

[0044] In step S107, the controller 270 analyses the identified candidate connections to exclude connections that are not feasible (e.g. where a connection could not be formed due to a RIS not being able to reflect signals between two nodes of an inter-non-terrestrial access point connection of that candidate connection). In this example, the feasible candidate connections include the fourth and sixth candidate connections.

[0045] In step S109, the controller 270 estimates one or more performance values for the feasible candidate connections. The estimated performance value or values are for the same properties as the performance requirements of the indirect connection (as determined in step S103). In this example, the controller 270 estimates the latency of each feasible candidate connection. The latency of the whole feasible candidate connection may be estimated, or the latency of the feasible candidate connection may be partly estimated and partly measured (that is, for any parts of the feasible candidate connection that already exist in the second NTN 200). Any estimates or measurements may be performed on demand or may be retrieved as previously estimated or measured values (stored in memory at the controller 170). The latency of each feasible candidate connection may be determined as a function of a respective propagation time of each hop in the feasible candidate connection and a respective processing time at each node in the feasible candidate connection. For example, the latency of the fourth candidate connection may be determined as a sum of:

[0046] • the propagation time between the gateway 220 and the primary non-terrestrial access point 230a (which may be estimated or measured),

[0047] • the processing time at the primary non-terrestrial access point 230a (which may be estimated or measured), • the propagation time between the primary non-terrestrial access point 230a and the first RIS 260a, and

[0048] • the propagation time between the first RIS 260a and the first secondary nonterrestrial access point 230b (which may be estimated or measured);

[0049] • the processing time at the first secondary non-terrestrial access point 230b (which may be estimated or measured);

[0050] • the propagation time between the first secondary non-terrestrial access point 230b and the second RIS 260b (which may be estimated or measured);

[0051] • the propagation time between the second RIS 260b and the second secondary non-terrestrial access point 230c;

[0052] • the processing time at the second secondary non-terrestrial access point 230c (which may be estimated or measured);

[0053] • the propagation time between the second secondary non-terrestrial access point 230c and the third RIS 260c (which may be estimated or measured); and

[0054] • the propagation time between the third RIS 260c and the fifth non-terrestrial access point 230e (which may be estimated).

[0055] In this example, the controller 270 estimates a latency of the fourth candidate connection as L4 and the latency of the sixth candidate connection as L5 (in which L5 > L4).

[0056] In step S1 11 , the controller 270 compares the estimated one or more performance values for each feasible candidate connection with corresponding performance requirements of the connection between the gateway 220 and the new non-terrestrial access point. Possible results of this comparison include:

[0057] 1 ) none of the one or more feasible candidate connections have estimated performance values that meet the corresponding performance requirements,

[0058] 2) one of the one or more feasible candidate connections have estimated performance values that meet the corresponding performance requirements, and

[0059] 3) two or more feasible candidate connections have estimated performance values that meet the corresponding performance requirements.

[0060] In the first scenario, following step S1 13 of Figure 4, the controller 270 performs one or more the following actions:

[0061] 1 ) reject the connection between the gateway 220 and the fifth non-terrestrial access point 230e; 2) accept the connection between the gateway 220 and the fifth non-terrestrial access point 230e but reduce a service level offered by the fifth non-terrestrial access point 230e;

[0062] 3) identify one or more candidate reconfigurations of the second NTN 200 that enable one or more additional candidate connections between the gateway 220 and the fifth non-terrestrial access point 230e (that would otherwise not be feasible without reconfiguration of the second NTN 200). The additional candidate connection(s) may then be analysed to determine if they satisfy the performance requirements of the connection.

[0063] An example of the third option of step S113 will now be described. A candidate reconfiguration of the second NTN 200 comprises the inter-non-terrestrial access point connection between the primary non-terrestrial access point 230a and the first secondary non-terrestrial access point 230b via the first RIS 260a reconfiguring to be via a first subarray of the first RIS 260a, and the inter-non-terrestrial access point connection between the first and second secondary non-terrestrial access points 230b, 230c via the second RIS 260b reconfiguring to be via a second subarray of the first RIS 260a. This candidate reconfiguration enables an additional feasible candidate connection between the gateway 220 and the fifth non-terrestrial access point 230e, the additional feasible candidate connection comprising the direct connection between the gateway 220 and the primary non-terrestrial access point 230a, the inter-non-terrestrial access point connection between the primary and first secondary non-terrestrial access points 230a, 230b via the first subarray of the first RIS 260a, and an inter-non-terrestrial access point connection between the first secondary non-terrestrial access point 230b and fifth nonterrestrial access point 230e via the second RIS 260b.

[0064] In the second scenario of step S11 1 , following step S115 of Figure 4 in which one of the one or more feasible candidate connections have estimated performance values that meet the corresponding performance requirements, the controller 270 accepts the connection between the gateway 220 and the fifth non-terrestrial access point 230e by using the one of the one or more feasible candidate connections having estimated performance values that meet the corresponding performance requirements. The controller 270 therefore sends an instruction message to each entity to implement the candidate connection. These instruction messages may be sent to any entity that must reconfigure or must be made aware of another entity’s reconfiguration (e.g. for recording in memory).

[0065] In the third scenario of step S1 11 , following step S117 of Figure 4 in which two or more feasible candidate connections have estimated performance values that meet the corresponding performance requirements, the controller 270 selects one of the two or more feasible candidate connections having estimated performance values that meet the corresponding performance requirements. The selection criterion / criteria may be based on one or more of, for example, the performance values (e.g. the best latency or capacity), the number of available reflecting elements at each RIS utilised in the candidate connection, and the candidate connection having the best link budget. Once a feasible candidate connection has been selected, then the method proceeds to step S1 15 (as described above).

[0066] As noted above, additional candidate connections may be enabled by a reconfiguration of the second NTN 200, which may be triggered following the first scenario of step S1 11 . If there are one or more additional candidate connections enabled by a reconfiguration, then the controller 270 may implement step S115 (and optionally S1 17 if there are multiple additional candidate connections) so as to implement the additional candidate connection. In this scenario, the instruction messages may reconfigure entities not directly involved in the candidate connection so as to implement the reconfiguration of the second NTN 200.

[0067] Once connected, each non-terrestrial access point in the second NTN 200 may indicate its performance values (e.g. its latency) to User Equipment (UE). These performance values may be part of a broadcast message, such as a System Information Block (SIB) message, such that they may be decoded by Idle UE in addition to connected UE. A UE may then determine, based on these performance values, which non-terrestrial access point to connect to (e.g. as a cell selection or during a handover).

[0068] In the above description, the non-terrestrial access point is part of a HAP. However, this is non-essential and the skilled person will understand that other forms of non-terrestrial access points may be used, in any combination, such as satellites or UAV. Furthermore, in the above description, the trigger for developing a connection (e.g. creating a new connection or reconfiguring an existing connection) that utilises a multihop inter-non-terrestrial access point connection is the controller 270 detecting the fifth non-terrestrial access point 230e that requires a new connection to the gateway 220. However, the method also applies to other triggers, such as a new connection between the gateway 220 and a new / existing UE via an existing multi-hop inter-non-terrestrial access point connection with the gateway 220. That is, when a new service link is required, such as when a UE is attempting to connect to the second NTN 200, the above method may be used to identify a connection (comprising a multi-hop inter-non-terrestrial access point connection and a service link to the UE) that satisfies the performance requirements of the new service link.

[0069] The second NTN 200 described above comprised a single gateway. However, the second NTN 200 may comprise a plurality of gateways, and one or more of the plurality of non-terrestrial access points 230 may be connected to multiple gateways. In this scenario, analysis of the candidate connections may involve analysis of candidate connections to each gateway, which may offer different performance values. Furthermore, the candidate reconfigurations (described above in relation to step S1 13) may involve a reconfiguration of the second NTN 200 such that non-terrestrial access points with an existing connection to the gateway 220 are reconnected via a different gateway.

[0070] The skilled person will also understand that other performance properties may also be analysed in the above method, such as received power.

[0071] The skilled person will understand that any combination of features is possible within the scope of the invention, as claimed.

Claims

CLAIMS1 . A method in a wireless telecommunications network, the wireless telecommunications network comprising: one or more gateways; a plurality of Reconfigurable Intelligent Surfaces, RISs; and a plurality of non-terrestrial access points; the method comprising the steps of: detecting a trigger to develop a connection in the wireless telecommunications network; obtaining data identifying a requirement for a performance parameter of the connection; obtaining data for a first candidate connection comprising at least two inter-non- terrestrial access point connections via a respective RIS of the plurality of RIS, the data identifying a first value of the performance parameter for the first candidate connection; comparing the first value of the performance parameter for the first candidate connection to the requirement for the performance parameter of the connection; and based on the comparison, developing the connection.

2. A method as claimed in Claim 1 , wherein the comparison step indicates that the first value of the performance parameter for the first candidate connection meets the requirement for the performance parameter of the connection.

3. A method as claimed in Claim 1 , further comprising the steps of: obtaining data for a second candidate connection comprising at least two inter- non-terrestrial access point connections via a respective RIS of the plurality of RIS, the data identifying a first value of the performance parameter for the second candidate connection; comparing the first value of the performance parameter for the second candidate connection to the requirement for the performance parameter for the connection, wherein both the first value of the performance parameter for the first candidate connection and the first value of the performance parameter for the second candidate connection meet the requirement for the performance parameter of the connection; selecting one of the first and second candidate connections,wherein the step of developing the connection uses the selected first or second candidate connection.

4. A method as claimed in Claim 2, further comprising the step of: identifying a candidate reconfiguration of the wireless telecommunications network, wherein the first candidate connection is based on the wireless telecommunications network as reconfigured in the candidate reconfiguration.

5. A method as claimed in Claim 3, further comprising the step of: identifying one or more candidate reconfigurations of the wireless telecommunications network, wherein the first and second candidate connections are based on the wireless telecommunications network as reconfigured in one or more of the candidate reconfigurations.

6. A method as claimed in any one of the preceding claims, wherein the connection is developed in response to one or more of a group comprising: a new non-terrestrial access point connecting to the wireless telecommunications network, and a new User Equipment, UE, connection being established in the wireless telecommunications network.

7. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of any one of Claims 1 to 6.

8. A computer readable carrier medium comprising the computer program of Claim7.

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