Restoring communication outages

Abstract

Restoring Communication Outages System comprising a first ground station comprising a first telecommunications node. A second ground station comprising a second telecommunications node. A first unmanned aerial vehicle, UAV, comprising a first transceiver and a first interface configured to communicate telecommunications traffic with the first telecommunications node. A second UAV comprising a second transceiver and a second interface configured to communicate telecommunications traffic with the second telecommunications node, wherein the first and second UAVs are further configured to provide a wireless communication link using the first and second transceivers, and further wherein the communication link provided by the first and second transceivers is configured to pass telecommunications traffic communicated between the first and second ground stations through the first and second telecommunications nodes and first and second interfaces.

Description

[0001] Restoring Communication Outages

[0002] Field of the Invention

[0003] The present invention relates to a system and method for providing a replacement telecommunications link when a fixed line, such as a fibre optic cable, breaks. The system includes two or more unmanned aerial vehicles that provide a wireless communication link to take the telecommunications traffic when the fixed line breaks.

[0004] Background of the Invention

[0005] Telecommunications network and other systems may use optical fibres to transmit high volumes of traffic, including voice and data. However, optical fibre can be susceptible to breakages and other outages. This can lead to outages of both mobile and fixed services. Although such networks are designed to include resilient paths, outages can still occur. Depending on the location of the fault, rectification and remedial work may require tens of hours (or more) to resolve.

[0006] Laying fixed lines or setting up mast-based microwave links to temporarily bridge the break may be impractical or unfeasible.

[0007] Therefore, there is required a method and system that overcomes these problems.

[0008] Summary of the Invention

[0009] An unmanned aerial vehicle, UAV, system provides telecommunications traffic (preferably cellular telecommunications traffic) services between two fixed points. When the fixed line between the two fixed points breaks or requires maintenance, the system can be used to temporarily restore communications between those two fixed points or ground stations, which would otherwise be provided by a fixed line connection (e.g., copper of fibre optic).

[0010] 16912714.HSS.HSS The UAV system may also be used on a more permanent basis when it is not feasible to provide fixed line communications at all, but the UAV system is more generally used to temporarily restore outages.

[0011] Two UAVs hover or fly substantially near or above each fixed point, which may be a ground station or other communications hub. The two UAVs remain close enough to each ground station so that they may maintain direct communications between the ground station and the UAV. Each UAV comprises at least a transceiver (e.g., a radio transceiver) used to maintain a communications link with the other UAV over or close to the other ground station. The transceiver may be the same or a different device to that used to maintain communications with the ground station.

[0012] Therefore, each UAV may simultaneously be in communication with a ground station and at least one other UAV. Communications traffic (e.g., voice and / or data) is passed between the ground stations and the UAVs. Therefore, the ground stations can remain indirectly in communication with each other through the communications link formed between the UAVs.

[0013] For more permanent installations, each UAV may be tethered or have a cable between the UAV and its corresponding ground station. The cable or tether can help maintain position of the UAV so that it does not drift too far from the ground station (e.g., due to wind). Optionally, the cable or tether may also be used to provide power to the UAV. Otherwise, each UAV may be powered by onboard batteries. Power supplied using the tether may be provided from a mains electricity connection attached to the ground station or another ground-based source (such as a generator or larger battery). A small back-up battery may be provided on each UAV, for example.

[0014] To bridge further distances when the outage may be larger over more difficult terrain, further UAVs may be used. For example, a third or fourth UAV may be flown (tethered or not) between the two UAV flying substantially above the ground stations. These additional UAVs do not need to communicate with the ground stations (or they may have an interface for doings so, but this can be deactivated). Instead, each additional UAV can simultaneously receive and transmit the communications traffic forming a multi-stage bridge of UAVs and transceivers between each ground station.

[0015] 16912714.HSS.HSS In further example implementations, the transceivers on board each LIAV may be line-of-sight transceivers (such as microwave, mm wave, or optical transceivers, for example). In this case, it is preferable for each UAV to further communicate data (e.g., telemetry data) with each other allowing the line-of-sight or directional signals to be maintained (e.g., + / - 3e). The further data (e.g., telemetry data) may be transmitted over an independent communications channel. For example, the independent communications channel may be a different channel, a channel of a different frequency, different communication mode, type or technology.

[0016] Against this background and in accordance with a first aspect there is provided a1 .

[0017] A system comprising: a first ground station comprising a first cellular telecommunications node; a second ground station comprising a second cellular telecommunications node; a first unmanned aerial vehicle, UAV, comprising a first transceiver and a first interface configured to communicate cellular telecommunications traffic with the first cellular telecommunications node; and a second UAV comprising a second transceiver and a second interface configured to configured to communicate cellular telecommunications traffic with the second cellular telecommunications node, wherein the first and second UAVs are further configured to provide a wireless communication link using the first and second transceivers, and further wherein the communication link provided by the first and second transceivers is configured to pass cellular telecommunications traffic communicated between the first and second ground stations through the first and second cellular telecommunications nodes and first and second interfaces. Therefore, breaks in fixed line communications can be rectified quickly and conveniently.

[0018] Optionally, the first cellular telecommunications node and / or the second cellular telecommunications node may be any one of: a wireless cellular telecommunications node; a wired cellular telecommunications node connectable with a tether of a UAV; or a fibre optic cellular telecommunications node connectable with a tether of a UAV.

[0019] The cellular telecommunications node may also comprise one or more interfaces (wireless, physical and / or electrical) that may be connectable or releasable, providing a convenient connection mechanism.

[0020] 16912714.HSS.HSS Optionally, the system may further comprise: a first tether configured to couple the first UAV to the first ground station; and a second tether configured to couple the second UAV to the second ground station. Therefore, the UAVs can be kept substantially at or over the ground stations. However, a physical tether is not always required. Instead, the UAVs can maintain their position substantially at or over the ground stations using software and other algorithms based on positional sensors and data (e.g., GPS). Other sensors that may be used may include radio, optical, pressure, gyroscopes, and / or accelerometers to maintain the location of the UAV(s).

[0021] Optionally, the first tether may be configured to transmit electrical power from the first ground station to the first UAV and / or transmit telecommunications traffic between the first telecommunications node of the first ground station to the first UAV, and / or wherein the second tether is configured to transmit electrical power from the first ground station to the second UAV and / or transmit cellular telecommunications traffic between the second cellular telecommunications node of the second ground station to the second UAV. The tether can stabilise each UAV, provide power, and / or communication connectivity.

[0022] Optionally, the system may further comprise one or more further UAVs comprising a further transceiver configured to transmit the cellular telecommunications traffic between the first and second UAVs and / or other UAVs within the communication link. Therefore, the communications link can be extended indefinitely with additional UAVs.

[0023] Optionally, the transceivers of the UAVs may be any one or more of: a wireless transceiver; an optical transceiver; a laser transceiver; a microwave transceiver; a millimetre transceiver; and / or a line-of-sight transceiver. Other transceiver types may be used.

[0024] Optionally, the first and second UAVs may further comprise: an alignment component configured to maintain alignment between the first UAV and the second UAV to maintain the wireless communication link, the alignment

[0025] 16912714. HSS.HSS component comprising a radio transmitter configured to transmit telemetry data between the LIAVs. Therefore, improved signals and bandwidth can be maintained over the communications link. The telemetry data may be transmitted over an independent communications channel. For example, the independent communications channel may be a different channel, a channel of a different frequency, different communication mode, type or technology.

[0026] Optionally, the alignment component may be configured to maintain alignment between elements of the first and second LIAVs. The elements may be elements holding or supporting the transceivers of each of the first and second UAVs. The elements may be gimbals. Additionally or alternatively, the elements may be other devices known in the art which are configured to actively move the transceivers relative to the UAV in two or three dimensions. The elements may comprise motors, gears, and other components.

[0027] Optionally, the system may further comprise: a UAV launch component, configured to launch the first and / or second UAV. Therefore, the system can be implemented quickly and effectively.

[0028] Preferably, the UAV launch component may be configured to be triggered by a loss of communication event between the first and second ground stations. This can provide automatic implementation of the system when required. The UAVs may be positioned or located at ground transmission sites ready to be launched in case of a failure (e.g., an optical fibre fails or is cut). In other example implementations, the UAVs may be brought to the ground stations after a failure has occurred and then launched manually to restore connectivity. Therefore, there may be mobile units available and ready to deploy UAVs when and where required.

[0029] Optionally, the first and second ground stations may further comprise optical fibre interfaces configured to provide an optical fibre communications link between the first and second ground stations. UAVs may be placed on standby and only activated or launched when a break or significant degradation in a fixed line is detected (e.g., by a separate remote monitoring station or a local monitor within a ground station). When the optical fibre is broken of otherwise fails then the system can be used to provide alternative communications between the ground stations.

[0030] 16912714.HSS.HSS Optionally, the system may further comprise any one or more of: a data switch; a modem; a traffic interface; and a radio frequency, RF, amplifier. Other components may be included. Each component may be located on the ground station(s) and / or the UAV(s).

[0031] Preferably, the data switch, the modem, and the traffic interface may be located on the first ground station and / or the second ground station, or the data switch, the modem, the traffic interface, and the RF amplifier are located on the first UAV and / or the second UAV. Other configurations may be used.

[0032] Optionally, the system may further comprise one or more balloons, configured to provide lift to the first and / or second UAV. This reduces power consumption and improves longevity of motors and other components of the UAV.

[0033] According to a second aspect, there is provided one or more unmanned aerial vehicle, UAV, comprising: a transceiver and an interface configured to communicate cellular telecommunications traffic with a cellular telecommunications node of a ground station, wherein the UAV is configured to provide a wireless communication link for the cellular telecommunications traffic with a second UAV using the transceiver. The UAV(s) may also comprise other components necessary for flight such as a flight controller, motors (e.g., 4, 6, 8, etc.), electronic speed controllers (ESCs), battery, frame, propellors, etc.

[0034] Optionally, the UAV may further comprise: an alignment component configured to maintain alignment between the UAV and the second UAV, the alignment component comprising a radio transmitter configured to transmit telemetry data between the UAVs (e.g., two-way communications between UAVs). The alignment may comprise a processor and one or more sensors. The telemetry data may be based on any of the sensor data or other control signals. The telemetry data may be transmitted over an independent communications channel.

[0035] Optionally, the alignment component may be configured to maintain alignment between elements of the UAV and the second UAV. The elements may be elements

[0036] 16912714.HSS.HSS holding or supporting the transceivers of each of the UAV and the second UAV. The elements may be gimbals. Additionally or alternatively, the elements may be other devices known in the art which are configured to actively move the transceivers relative to the UAV in two or three dimensions. The elements may comprise motors, gears, and other components.

[0037] Preferably, the alignment component may be further configured to maintain a position of the UAV substantially above the ground station. The alignment component in one UAV may be further configured to generate correction commands sent to another UAV, for example.

[0038] Preferably, the UAV(s) may further comprise a tethering component, configured to tether the UAV to the ground station. This may provide further stability and reduce drift maintaining the UAV close to around and / or above its corresponding ground station.

[0039] According to a third aspect, there is provided one or more ground station comprising: a cellular telecommunications node configured to communicate cellular telecommunications traffic to an interface of an unmanned aerial vehicle, UAV; a tether, configured to tether the UAV to the ground station; and an optical fibre interface configured to provide an optical fibre communications link between ground station and a second ground station.

[0040] According to a further aspect, there is provided a method for maintaining line-of- sight between two or more of the UAVs described above. The method comprises the steps of: a first UAV transmitting telemetry data; a second UAV receiving the telemetry data transmitted by the first UAV; a second UAV transmitting telemetry data; a first UAV receiving the telemetry data transmitted by the second UAV; and the first and second UAVs processing the received telemetry data together with their own telemetry data using an algorithm to determine if and how to alter their own flights so that alignment between transceivers of each of the first and second UAV is maintained.

[0041] 16912714.HSS.HSS The telemetry data may be transmitted over an independent communications channel. For example, the independent communications channel may be a different channel, a channel of a different frequency, different communication mode, type or technology.

[0042] Optionally, the method may be configured to maintain alignment between elements other than the transceivers of the first UAV and the second UAV. The elements may be elements holding or supporting the transceivers of each of the first UAV and the second UAV. The elements may be gimbals. Additionally or alternatively, the elements may be other devices known in the art which are configured to actively move the transceivers relative to the UAV in two or three dimensions. The elements may comprise motors, gears, and other components.

[0043] The methods described above may be implemented as a computer program comprising program instructions to operate a computer. The computer program may be stored on a computer-readable medium, including a non-transitory computer-readable medium.

[0044] The computer system may include a processor or processors (e.g., local, virtual or cloud-based) such as a Central Processing Unit (CPU), and / or a single or a collection of Graphics Processing Units (GPUs). The processor may execute logic in the form of a software program. The computer system may include a memory including volatile and nonvolatile storage medium. A computer-readable medium (CRM) may be included to store the logic or program instructions. For example, embodiments may include a non-transitory computer-readable medium (CRM) storing software comprising instructions executable by one or more computers which, upon such execution, cause the one or more computers to perform the disclosed methods. Non-transitory CRM may refer to a CRM that stores data for short periods or in the presence of power such as a memory device or Random Access Memory (RAM). For example, a non-transitory computer-readable medium may include storage components, such as, a hard disk (e.g., a magnetic disk, an optical disk, a magneto-optic disk, and / or a solid state disk), a compact disc (CD), a digital versatile disc (DVD), a floppy disk, a cartridge, and / or a magnetic tape. The different parts of the system may be connected using a network (e.g. wireless networks and wired networks). The computer system may include one or more interfaces. The computer system may contain a suitable operating system such as UNIX, Windows (RTM) or Linux, for example.

[0045] 16912714.HSS.HSS The ground stations of any aspect of the invention may be cellular base stations. For example, the ground stations may be gNodeBs or any other cellular base station according to the 2G, EDGE, 3G, HSDPA, 4G, LTE, or 5G communications standards or any other cellular communications standard known in the art.

[0046] There are particular challenges involved with redundancy in cellular base stations. For example, cellular base stations may be located in remote or difficult to reach locations. This may result in it being difficult or time-consuming to effect repairs to physical communications channels between cellular base stations. Furthermore, access to cellular telecommunications services in certain geographical areas may be provided by a single cellular base station. If this base station is disconnected from the other cellular base stations of the cellular communications network, this may result in access to the cellular telecommunications service being lost for that geographical area. As such, it is important in the case of cellular telecommunications to be able to have reliable and rapid redundancies available in the case of a communications failure between cellular base stations.

[0047] It should be noted that any feature described above may be used with any particular aspect or embodiment of the invention.

[0048] The following numbered clauses describe further illustrative examples only:

[0049] 1 . A system comprising: a first ground station comprising a first telecommunications node; a second ground station comprising a second telecommunications node; a first unmanned aerial vehicle, UAV, comprising a first transceiver and a first interface configured to communicate telecommunications traffic with the first telecommunications node; and a second UAV comprising a second transceiver and a second interface configured to communicate telecommunications traffic with the second telecommunications node, wherein the first and second UAVs are further configured to provide a wireless communication link using the first and second transceivers, and further wherein the communication link provided by the first and second transceivers is configured to pass telecommunications traffic communicated between the

[0050] 16912714. HSS.HSS first and second ground stations through the first and second telecommunications nodes and first and second interfaces.

[0051] 2. The system according to any previous clause, wherein the first telecommunications node and / or the second telecommunications node are any one of: a wireless telecommunications node; a wired telecommunications node connectable with a tether of a UAV; or a fibre optic telecommunications node connectable with a tether of a UAV.

[0052] 3. The system of clause 1 or clause 2 further comprising: a first tether configured to couple the first UAV to the first ground station; and a second tether configured to couple the second UAV to the second ground station.

[0053] 4. The system of clause 3, wherein the first tether is configured to transmit electrical power from the first ground station to the first UAV and / or transmit telecommunications traffic between the first telecommunications node of the first ground station to the first UAV, and / or wherein the second tether is configured to transmit electrical power from the second ground station to the second UAV and / or transmit telecommunications traffic between the second telecommunications node of the second ground station to the second UAV.

[0054] 5. The system according to any previous clause further comprising: one or more further UAVs comprising a further transceiver configured to transmit the telecommunications traffic between the first and second UAVs and / or other UAVs within the communication link.

[0055] 6. The system according to any previous clause, wherein the transceivers of the UAVs are any one or more of: a wireless transceiver; an optical transceiver; a laser transceiver; a microwave transceiver; a millimetre transceiver; and / or a line-of-sight transceiver.

[0056] 16912714.HSS.HSS 7. The system according to any previous clause, wherein the first and second UAVs further comprise: an alignment component configured to maintain alignment between the first UAV and the second UAV to maintain the wireless communication link, the alignment component comprising a radio transmitter configured to transmit telemetry data between the UAVs.

[0057] 8. The system according to any previous clause, further comprising: a UAV launch component, configured to launch the first and / or second UAV.

[0058] 9. The system of clause 8, wherein the UAV launch component is configured to be triggered by a loss of communication event between the first and second ground stations.

[0059] 10. The system according to any previous clause, wherein the first and second ground stations further comprise optical fibre interfaces configured to provide an optical fibre communications link between the first and second ground stations.

[0060] 1 1 . The system according to any previous clause further comprising any one or more of: a data switch; a modem; a traffic interface; a radio frequency, RF, amplifier; and a laser transceiver.

[0061] 12. The system of clause 1 1 , wherein the data switch, the modem, and the traffic interface are located on the first ground station and / or the second ground station, or the data switch, the modem, the traffic interface, and the RF amplifier are located on the first UAV and / or the second UAV.

[0062] 13. The system according to any previous clause further comprising one or more balloons, configured to provide lift to the first and / or second UAV.

[0063] 14. An unmanned aerial vehicle, UAV, comprising:

[0064] 16912714.HSS.HSS a transceiver and an interface configured to communicate telecommunications traffic with a telecommunications node of a ground station, wherein the UAV is configured to provide a wireless communication link for the telecommunications traffic with a second UAV using the transceiver.

[0065] 15. The UAV of clause 14 further comprising : an alignment component configured to maintain alignment between the UAV and the second UAV, the alignment component comprising a radio transmitter configured to transmit telemetry data between the UAVs.

[0066] 16. The UAV of clause 15, wherein the alignment component is further configured to maintain a position of the UAV substantially above the ground station.

[0067] 17. The UAV according to any of clause 14 to 16 further comprising a tethering component, configured to tether the UAV to the ground station.

[0068] 18. A ground station comprising: a telecommunications node configured to communication telecommunications traffic to an interface of an unmanned aerial vehicle, UAV; a tether, configured to tether the UAV to the ground station; and an optical fibre interface configured to provide an optical fibre communications link between ground station and a second ground station.

[0069] Brief description of the Figures

[0070] The present invention may be put into practice in a number of ways and embodiments will now be described by way of example only and with reference to the accompanying drawings, in which:

[0071] FIG. 1 shows a schematic diagram of a portion of a telecommunications system, including a fixed line;

[0072] FIG. 2 shows a schematic diagram of the portion of the telecommunications system of Figure 1 , with a break in the fixed line;

[0073] FIG. 3 shows a schematic diagram of an example system for resolving the break in the fixed line of Figures 1 and 2, including ground stations and unmanned aerial vehicles (UAVs);

[0074] 16912714.HSS.HSS FIG. 4 shows a schematic diagram of the ground station and UAV of Figure 3 in more detail;

[0075] FIG. 5 shows a schematic diagram of a further example system for resolving the break in the fixed line of Figures 1 and 2, including ground stations and unmanned aerial vehicles (UAVs);

[0076] FIG. 6 shows a schematic diagram of the ground station and UAV of Figure 3 together with an optional balloon;

[0077] FIG. 7 shows a flowchart of a method for maintaining alignment between the UAVs of the systems of Figures 2 and 4; and

[0078] FIG. 8 shows a schematic diagram of a computer system used to implement the method of Figure 7.

[0079] It should be noted that the figures are illustrated for simplicity and are not necessarily drawn to scale. Like features are provided with the same reference numerals.

[0080] Detailed description of the preferred embodiments

[0081] Figure 1 shows a schematic diagram of a system for providing communications traffic between two fixed points or ground stations 20, 25 over a fixed line 35 that may be wired (e.g., copper cable) or fibre optic cable. In this example, the ground stations may be base stations (e.g., gNodeB) or any other telecommunications facilities.

[0082] The fixed line 35 can generally carry a high traffic volume and may be used to provide connectivity within a larger telecommunications network. However, such fixed lines may be susceptible to damage or require routine maintenance taking them out of service for a period of time. Figure 2 illustrates such an event with the fixed line 35 incurring a physical break 45. Under these circumstances all telecommunications traffic between the ground stations 20, 25 will cease until the break is fixed, which can take many hours or even days in remote locations.

[0083] Figure 3 illustrates a system 10 used to resolve or at least temporarily resolve the outage illustrated in Figure 2. The same ground stations 20, 25 are shown in Figure 3 with the same break 45 in the fixed line 35. However, the communications traffic is now diverted to take an alternative path so that communications between the ground stations 20, 25 is restored. This alternative path is provided by a first unmanned aerial vehicle (UAV) 40 flown substantially above the first ground station 20 and a second UAV 60 flow

[0084] 16912714.HSS.HSS substantially above the second ground station 40. Each of the first and second UAV has a transceiver used to form a communications link 70 between them. The first UAV 40 has an interface used to communicate with the first ground station 20. The second UAV 60 has an interface used to communicate with the second ground station 25. These interfaces may be part of the transceivers used to communicate between the UAVS or a separate interface. Therefore, communications traffic that originally passed directly between the first and second ground stations is diverted from the first ground station 20 to the first UAV 40 over a first ground to air link 30, from the first UAV 40 to the second UAV 60 over the communications link 70 provided by the transceivers on the first and second UAVs, and from the second UAV 60 to the second ground station 25 over a second ground to air link 50. The fixed line 35 may extend for a substantial distance (e.g., tens of kilometres).

[0085] Figure 4 illustrates schematically the ground to air link 30 between the first ground station 20 and the first UAV 40. However, the second ground to air link 50 works in the same way. The ground to air link 30 is achieved using an interface 100 on the UAV 40 communicating with an interface of a telecommunications node 110 on the ground station 20. Similar interfaces and telecommunications nodes 110 are located on the second UAV 60 and the second ground station 25.

[0086] The ground to air links 30, 50 may be wireless, optical, microwave or wired, for example. In the example implementations shown in Figure 1 to 6, the ground to air links 30, 50 include a tether or cable that provides any one of three functions. The first function is to tether the first or second UAV 40, 60 to the first or second ground stations 20, 25, respectively. This prevents the UAVs 40, 60 from drifting, especially in high winds. The second function is to provide electrical power to the UAVs 40, 60 so that they can remain in the air for extended periods or indefinitely, avoiding the need for battery changes. The third function is to provide a wired or optical fibre communications link between the ground stations 20, 25 and the UAVs 40, 60. The ground to air links 30, 50 can provide any one or more of these functions but preferably all three.

[0087] Figure 5 illustrates schematically a further example implementation of the system 200. Similar reference numbers are used for similar features. In this example implementation the communications link 70 is provided in separate sections. This is done to increase the length of the communications link 70, which may be beyond the range of the transceivers located on each of the first and second UAVs 40, 60. One or more

[0088] 16912714.HSS.HSS additional LIAVs 210 is located between the first and second LIAVs 40, 60. These one or more additional LIAVs 210 may be similar or the same as the first and second LIAVs 40, 60. However, they do not require (or need to use) the interface 100 with the ground station as they only communicate with out LIAVs using their transceiver.

[0089] In this example implementation the communications link 70 is divided into two sections 270 and 275. The first section 270 is between the first UAV 40 hovering above or around the first ground station 20 (tethered on otherwise) and the additional UAV(s) 210. The second section 275 is between the additional UAV(s) 210 and the second UAV 60 hovering above or around the first ground station 25 (tethered on otherwise).

[0090] Figure 6 illustrates schematically a further example implementation including a balloon 400 providing additional or supplementary lift to the first UAV 40. The balloon is joined to the first UAV 40 using a further tether or cable 410. The second (or additional) UAV 60 may also be provided with a balloon 400 attached using a tether or cable 410. The balloon can be used to reduce the power necessary to keep the UAVs airborne. As the UAVs are substantially static then the balloons 400 should not interfere with their flight.

[0091] During operation, any one or more of the UAVs can be replaced by a replacement UAV, while maintaining the communications link 70. This can be done to replace a damaged or faulty UAV or to replace a depleted battery on a UAV, for emample.

[0092] The present system provides at least a temporary outage resolution by using UAVs (e.g., drones and / or balloons) providing connectivity between at least two distant points. This can be achieved quickly and with enough bandwidth to carry a significant part (or all) of the broken traffic.

[0093] As shown in Figures 3 and 5, the system 10 is formed from three sections or legs.

[0094] Leg 1 and leg 3 are the ground to air links 30 and 50, respectively. Each of leg 1 and 3 is formed using a UAV connected to a ground station that may be a transport point or a base station, which can be connected to the UAV wirelessly or by using cable or tether. The cable or tether may optionally be used to carry power to the UAF. The UAV can be a drone, or a balloon preferably kept on substantially at a specific position by a drone).

[0095] 16912714.HSS.HSS Leg 2 is the communications link 70, which is a wireless link (e.g., microwave, optic, laser, mm wave, etc.). The distance between the first UAV 40 and the second UAV 60, as well as any payload that can be lifted by each UAV may define the available bandwidth provided by the system 10 (e.g., measured in Gbps).

[0096] In the system 200, the communications link 70 (leg 2) may include a wireless repeater (e.g., supported by a further UAV or UAVs 210) that can extend the communications link 70 overcoming any limit on distance and / or bandwidth imposed by only having two UAVs. In an example implementation, up to 4 Gbps at 50 km may be achieved.

[0097] In a further example implementation, a set of trolleys or boxes, containing the UAVs 40, 60 and any other equipment, may be dispatched to a site together with a field technician. When an outage occurs (e.g., an optical fibre break), the technician can go to the first and second ground stations and set up the UAVs 40, 60 that they will be used to provide the communications link 70 and communicate with and / or be tethered to each ground station.

[0098] The communications link 70 may include components providing a suitable wireless connection. These components may be housed on or within each UAV 40, 60 and / or on the first and second ground stations 20, 25. In an example implementation, microwave transceivers may be used. The microwave equipment or components may be all outdoor (AO) or may be split between an indoor unit (IDU) and an outdoor unit (ODU). In one example implementation, the IDU may comprise any one or more of a switching component, a modem processing component, and one or more traffic interfaces. The ODU may include radio frequency (RF) components such as power amplifiers.

[0099] In a first example implementation (option 1 ) the IDU may stay on the ground within or connected to a ground station 20, 25. The IDU may be connected (e.g., using a cable or tether) to the ODU, which may be located onboard the UAV 40, 60).

[0100] In a second example implementation (option 2) both the IDU and the ODU may be located on the UAV 40, 60. The connecting cable or tether can provide a fibre optic connection and a power supply connection.

[0101] 16912714.HSS.HSS In a third example implementation (option 3) the IDU may be placed into an intermediate or additional UAV with the ODll located on another LIAV nearby.

[0102] In a fourth example implementation (option 4) the cables can be replaced by radio technology like mmWave (or another communication protocol and technology) with no physical tether or cable connecting the UAV 40, 60 to each ground station 20, 25. However, in this case the UAV and related equipment may not receive power from the ground, and so would require larger batteries to maintain the communications link 70 for extended periods (e.g., greater than a few hours). Optical links between the ground stations 20, 25 and the UAVs 40, 60 may also be used.

[0103] Mechanical interfaces may also be included in the system 10, 200 to connect equipment. For example, each ground station 20, 25 may include a mechanical interface allowing the system 10, 200 to be implemented remotely.

[0104] The transceivers 100 located on each UAV 40, 60, 210 may be line-of-sight transceivers, such as microwave or laser transceivers, for example. Line-of-sight transceivers require visibility between their antennas or communication nodes to maintain a high performance and reliable connection over the communications link 70. In an example implementation, each UAV 40, 60, 210 may communicate (preferably over a separate radio channel using separate transceivers) telemetry data with each other. This may also be provided over a cellular or non-terrestrial network (NTN). These telemetry data may include precise coordinates and / or the orientation of the (or each) other UAV. These data may be transmitted using two-way communications. Such data may be changed as the UAV is moved or buffeted (e.g., due to the wind). Therefore, the system 10, 200 may provide a mechanism for joint control of the position or both (or all) UAVs. A central processing unit (e.g., on one UAV or located on the ground) may coordinate all UAVs and receive the telemetry data from each UAV and send out flight correction or control instructions, for example. In any case, flight control commands may be implemented by flight controllers on each UAV managing power to individual motors, for example.

[0105] The level of precision required in this telemetry control system depends on the wireless technology used within the communications link 70. For example, for a microwave link, this may require + / - 1e. For an optical link a + / - 3eprecision may be required. A second radio technology may be used by each UAV 40, 60, 210 when exchanging mutual

[0106] 16912714.HSS.HSS position information or telemetry data. Adjustment of flight controls may be made to maintain antenna alignments and reduce latency in the communications link 70.

[0107] Figure 7 shows a flowchart of a high level method 700 for maintaining alignment between two or more LIAVs. The method loops continuously with each LIAV transmitting telemetry data including position and attitude information. These data may be used to alter the operating or flight instructions, which maintains a line-of-sight and / or the orientation of directional antennas or optical transceivers on each UAV so that they remain aligned to maintain the communications link 70 between the LIAVs.

[0108] At step 715 the first UAV 40 transmits its telemetry data, and this is received by the second UAV 60 at step 720. At step 725 the second UAV 60 transmits its telemetry data, and this is received by the second UAV 40 at step 730. The first and second UAVs 40, 60 process the received telemetry data together with their own telemetry data at step 735 using an algorithm to determine if and how to alter their own flight characteristics so that alignment between their transceivers 100 is maintained. The telemetry data may be transmitted and received by separate transceivers to the transceiver 100 used to maintain the communications link 70. The algorithm may be executed by a computer system 800 within each UAV 40, 60. The method 700 may be repeated or executed concurrently between each pair of UAVs forming the communications link 70. Processing may alternatively take place external to each UAV with each UAV taking commands from a separate processor operating the alignment algorithm.

[0109] The following provides a more detailed description of an example implementation of the method 700 described, with reference to Figure 7. The UAV require alignment with each other to ensure an effective wireless connection between their transceivers (first and second transceivers located on each UAV). This maintains radio link performance over a significant distances. In particular, microwave and optical links operate more effectively the transceivers maintain a line of sight and with antenna alignment within + / - 0.5 degree).

[0110] Two example alignment mechanisms can operate in parallel:

[0111] A. Coarse alignment (e.g., aiming for an alignment accuracy of + / - 2 to 5 degrees).

[0112] 16912714.HSS.HSS The objective of this course alignment is to maintain the LIAVs aligned with each other and to maintain line of sight of their antennas corresponding to the first and second transceivers. Such alignment can be executed using out of band communications (i.e., data exchanged outside the microwave, optic, mmWave wireless technology that is used to provide the telecommunications traffic over the communications link between the first and the second or more LIAVs.

[0113] Each UAV may have a satellite positioning receiver (e.g., GPS, Galileo, etc.), accelerometers and / or gyroscopes used to determine position (location and / or orientation) of each UAV and antennas of each UAV. In this example implementation, one of the UAVs (e.g., arbitrarily selected) may act as a master for the coarse alignment process. The second (and subsequent UAVs) may send to the master UAV its precise position and antenna position using another wireless technology, preferably separate from the communications line. For example, these may include any one or more of:

[0114] 1 . A UAV-to-UAV bidirectional direct communication, realised using an additional transceiver on each UAV supporting any wireless technology capable of transmitting kbps data over a distance up to tens of kilometres (e.g., 2G, 4G over 700 / 800 / 900MHz band); and / or

[0115] 2. A UAV-to-UAV bidirectional communication conveyed through existing terrestrial Network coverage or satellite system coverage. The master UAV may then send alignment commands to the second and subsequent UAVs based on these received data.

[0116] B. Finer alignment (e.g., preferably providing an alignment accuracy of + / - 0.5 degrees).

[0117] This may be realised using the in-bound communications over the already established first wireless link (the communications link) provided by the first and the second (and subsequent in case of more UAVs) transceivers on each UAV.

[0118] As shown in Figure 8, the computer system 800 includes a number of components including communication interfaces 820, system circuitry 830, input / output (I / O) circuitry 140, display circuitry and interfaces 850 (optional), and a datastore 870. The system circuitry 820 can include one or more processors or CPUs 880 and memory 890. The system circuitry 830 may include any combination of hardware, software, firmware, and / or

[0119] 16912714.HSS.HSS other circuitry. The system circuitry 830 may be implemented, with one or more systems on a chip (SoC), application specific integrated circuits (ASIC), microprocessors, and / or analogue and digital circuits.

[0120] The optional display circuitry may provide one or more graphical user interfaces (GUIs) 860 and the I / O interface circuitry 840 may include touch sensitive or non-touch displays, sound, voice or other recognition inputs, buttons, switches, speakers, sounders, and other user interface elements. The I / O interface circuitry 840 may include microphones, cameras, headset and microphone input / output connectors, Universal Serial Bus (USB) connectors, and SD or other memory card sockets. The I / O interface circuitry 140 may further include data media interfaces (e.g., a CD-ROM or DVD drive) and other bus and display interfaces.

[0121] The memory 890 may include volatile (RAM) or non-volatile memory (e.g., ROM or Flash memory). The memory may store the operating system 892 of the computer system 800, applications or software 894, dynamic data 896, and / or static data 898. The datastore or data source 870 may include one or more databases 872, 874 and / or a file store or file system, for example.

[0122] The method and system may be implemented in hardware, software, or a combination of hardware and software. The method and system may be implemented either as a server comprising a single computer system or as a distributed network of servers connected across a network. Any kind of computer system or other electronic apparatus may be adapted to carry out the described methods.

[0123] As used throughout, 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 an ion multipole device) means "one or more" (for instance, one or more ion multipole device). 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 but not limited to", and are not intended to (and do not) exclude other components. Also, the use of “or” is inclusive, such that the phrase “A or B” is true when “A” is true, “B is true”, or both “A” and “B” are true.

[0124] 16912714.HSS.HSS 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 disclosure and does not indicate a limitation on the scope of the disclosure unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosure.

[0125] The terms “first” and “second” may be reversed without changing the scope of the disclosure. That is, an element termed a “first” element may instead be termed a “second” element and an element termed a “second” element may instead be considered a “first” element.

[0126] 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.

[0127] It is also to be understood that, for any given component or embodiment described throughout, any of the possible candidates or alternatives listed for that component may generally be used individually or in combination with one another, unless implicitly or explicitly understood or stated otherwise. It will be understood that any list of such candidates or alternatives is merely illustrative, not limiting, unless implicitly or explicitly understood or stated otherwise.

[0128] Unless otherwise described, all technical and scientific terms used throughout have a meaning as is commonly understood by one of ordinary skill in the art to which the various embodiments described herein belongs.

[0129] As will be appreciated by the skilled person, details of the above embodiment may be varied without departing from the scope of the present invention, as defined by the appended claims.

[0130] For example, whilst two, three and four UAVs have been shown in the figures, any number of UAVs may be used to bridge a particular break 45 in the fixed line 35. The fixed line may be any communications link and not limited to a communications link in a telecommunications or cellular network.

[0131] Many combinations, modifications, or alterations to the features of the above embodiments will be readily apparent to the skilled person and are intended to form part of the invention. Any of the features described specifically relating to one embodiment or example may be used in any other embodiment by making the appropriate changes.

[0132] 16912714.HSS.HSS

Claims

CLAIMS:1 . A system comprising: a first ground station comprising a first cellular telecommunications node; a second ground station comprising a second cellular telecommunications node; a first unmanned aerial vehicle, UAV, comprising a first transceiver and a first interface configured to communicate cellular telecommunications traffic with the first cellular telecommunications node; and a second UAV comprising a second transceiver and a second interface configured to communicate cellular telecommunications traffic with the second cellular telecommunications node, wherein the first and second UAVs are further configured to provide a wireless communication link using the first and second transceivers, and further wherein the communication link provided by the first and second transceivers is configured to pass cellular telecommunications traffic communicated between the first and second ground stations through the first and second cellular telecommunications nodes and first and second interfaces.

2. The system according to any previous claim, wherein the first cellular telecommunications node and / or the second cellular telecommunications node are any one of: a wireless cellular telecommunications node; a wired cellular telecommunications node connectable with a tether of a UAV; or a fibre optic cellular telecommunications node connectable with a tether of a UAV.

3. The system of claim 1 or claim 2 further comprising: a first tether configured to couple the first UAV to the first ground station; and a second tether configured to couple the second UAV to the second ground station.

4. The system of claim 3, wherein the first tether is configured to transmit electrical power from the first ground station to the first UAV and / or transmit cellular telecommunications traffic between the first cellular telecommunications node of the first ground station to the first UAV, and / or wherein16912714.HSS.HSSthe second tether is configured to transmit electrical power from the second ground station to the second UAV and / or transmit cellular telecommunications traffic between the second cellular telecommunications node of the second ground station to the second UAV.

5. The system according to any previous claim further comprising: one or more further UAVs comprising a further transceiver configured to transmit the cellular telecommunications traffic between the first and second UAVs and / or other UAVs within the communication link.

6. The system according to any previous claim, wherein the transceivers of the UAVs are any one or more of: a wireless transceiver; an optical transceiver; a laser transceiver; a microwave transceiver; a millimetre transceiver; and / or a line-of-sight transceiver.

7. The system according to any previous claim, wherein the first and second UAVs further comprise: an alignment component configured to maintain alignment between the first UAV and the second UAV to maintain the wireless communication link, the alignment component comprising a radio transmitter configured to transmit telemetry data between the UAVs.

8. The system according to claim 7 wherein the telemetry data is transmitted over an independent communications channel.

9. The system according to any previous claim, further comprising: a UAV launch component, configured to launch the first and / or second UAV.

10. The system of claim 9, wherein the UAV launch component is configured to be triggered by a loss of communication event between the first and second ground stations.16912714.HSS.HSS11 . The system according to any previous claim, wherein the first and second ground stations further comprise optical fibre interfaces configured to provide an optical fibre communications link between the first and second ground stations.

12. The system according to any previous claim further comprising any one or more of: a data switch; a modem; a traffic interface; a radio frequency, RF, amplifier; and a laser transceiver.

13. The system of claim 12, wherein the data switch, the modem, and the traffic interface are located on the first ground station and / or the second ground station, or the data switch, the modem, the traffic interface, and the RF amplifier are located on the first UAV and / or the second UAV.

14. The system according to any previous claim further comprising one or more balloons, configured to provide lift to the first and / or second UAV.

15. The system according to any previous claim wherein the first and / or second ground stations are cellular base stations.

16. An unmanned aerial vehicle, UAV, comprising: a transceiver and an interface configured to communicate cellular telecommunications traffic with a cellular telecommunications node of a ground station, wherein the UAV is configured to provide a wireless communication link for the cellular telecommunications traffic with a second UAV using the transceiver.

17. The UAV of claim 16 further comprising: an alignment component configured to maintain alignment between the UAV and the second UAV, the alignment component comprising a radio transmitter configured to transmit telemetry data between the UAVs.

18. The UAV according to claim 17 wherein the telemetry data is transmitted over an independent communications channel.16912714.HSS.HSS19. The UAV of any of claims 17 or 18, wherein the alignment component is further configured to maintain a position of the UAV substantially above the ground station.

20. The UAV according to any of claims 16 to 19 further comprising a tethering component, configured to tether the UAV to the ground station.21 . The UAV according to any of claims 16 to 20 wherein the ground station is a cellular base station.

22. A ground station comprising: a cellular telecommunications node configured to communicate telecommunications traffic to an interface of an unmanned aerial vehicle, UAV; a tether, configured to tether the UAV to the ground station; and an optical fibre interface configured to provide an optical fibre communications link between ground station and a second ground station.

23. The ground station of claim 22 wherein the ground station is a cellular base station.

24. A method for maintaining line-of-sight between two or more of the UAVs according to any of claims 16 to 21 , the method comprising the steps of: a first UAV transmitting telemetry data; a second UAV receiving the telemetry data transmitted by the first UAV; a second UAV transmitting telemetry data; a first UAV receiving the telemetry data transmitted by the second UAV; and the first and second UAVs processing the received telemetry data together with their own telemetry data using an algorithm to determine if and how to alter their own flights so that alignment between transceivers of each of the first and second UAV is maintained.

25. A computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the method of claim 24.16912714. HSS.HSS

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