Radio zone reselection for UAVs in cellular networks

Abstract

A method, apparatus and computer program for assisting an unmanned aerial vehicle (UAV) (10) in performing a serving radio area reselection are proposed. The UAV (10) is connected to a cellular network via a serving radio area and is also associated with a UAV application server (UAV‑AS) (100). The method is performed by the UAV‑AS (100) and includes: receiving a request to allocate a flight path for the UAV (10) to use for traveling to a destination point, and after the flight path has been allocated, determining a list of radio areas suitable as serving radio areas along the allocated flight path, and providing the list of radio areas to the requester to assist the UAV (10) in performing a serving radio area reselection. The method performed by the UAV (10) includes: receiving a request to travel to a destination point; and after the flight path has been allocated, receiving from the UAV‑AS (100) a list of radio areas suitable as serving radio areas along the allocated flight path, and while traveling along the allocated flight path, performing a serving radio area reselection to a radio area from the list of radio areas in order to maintain connection with the cellular network.

Description

Technical Field

[0001] The present invention relates to telecommunications, and in particular to a system, method, node and computer program for an unmanned aerial vehicle (UAV) to perform service radio area reselection while driving and for a UAV application server (UAV-AS) to assist the UAV in performing service radio area reselection. Background Art

[0002] New delivery services or emergency services will require specific unmanned aerial vehicles (UAVs) to transport products or perform surveillance.

[0003] The architecture presented here is based on a dedicated UAV-AS that is used by any UAV using a specific cellular network when the UAV is activated. When the UAV-AS is put into service, the UAV-AS is within the operator's management range and is automatically detected and connected to the cellular network.

[0004] Today's terrestrial radio network planning and optimization depends on several factors like environmental and other boundary conditions (e.g. terrain, available frequencies, etc.) to consider coverage, capacity requirements and quality targets. The current focus is on providing services to objects on or near the ground or in buildings.

[0005] However, if Figure 1 As depicted, the situation is very different for a UAV flying at a higher altitude. A UAV in the air will see more radio areas than a ground-based UE. Due to the lack of obstacles, the reach of the radio areas is much higher and more dependent on weather conditions than on the ground.

[0006] This results in a situation where the radio zones do not appear in the same way as perceived by a ground-based UE. The UAV sees more radio zones, and the radio zones are longer in reach. The UAV 10 is connected to the cellular network via the serving radio zone. However, due to the altitude of the UAV flight path, there are many interfering or alternative radio zones.

[0007] A UAV may fly from location A to location B at a certain altitude. Therefore, the UAV will face several handovers between radio zones, having to reselect the serving radio zone more frequently. Therefore, a lot of signaling is triggered, the UAV is often unnecessarily active, and this reduces the charge level of the UAV power supply. The signaling also affects the network performance of the cellular network for other ground-based services.

[0008] Frequent handover or radio zone reselection also negatively impacts the user experience of UAV services. In the worst case, a fast-flying UAV may not have enough time to successfully complete the handover or radio zone reselection process because the UAV may have detected more upcoming radio zones when it arrives at the destination. Summary of the invention

[0009] There is clearly a need for a method and corresponding apparatus for a UAV-AS to perform optimized serving radio zone reselection while driving and for assisting a UAV in performing such optimized serving radio zone reselection.

[0010] This object is achieved by the independent claim. Advantageous embodiments are described in the dependent claims.

[0011] According to an exemplary aspect of the present invention, a method for assisting an unmanned aerial vehicle (UAV) in performing a service radio area reselection is provided. The UAV is connected to a cellular network via a service radio area and is also associated with a UAV application server (UAV-AS). The method is performed by the UAV-AS and includes: receiving a request for allocating a flight path for the UAV to use for traveling to a destination point; after allocating the flight path, determining a list of radio areas suitable as service radio areas along the allocated flight path; and providing the list of radio areas to the requester to assist the UAV in performing a service radio area reselection.

[0012] According to a further exemplary aspect of the invention, a method for performing a serving radio zone reselection by an unmanned aerial vehicle (UAV) is provided. The UAV is connected to a cellular network via a serving radio zone and is also associated with a UAV application server (UAV-AS). The method is performed by the UAV and comprises: receiving a request to travel to a destination point; after a flight path has been assigned, receiving from the UAV-AS a list of radio zones suitable as serving radio zones along the assigned flight path; and while travelling along the assigned flight path, performing a serving radio zone reselection to a radio zone from the list of radio zones in order to maintain connection with the cellular network.

[0013] According to a further exemplary aspect of the present invention, an application server UAV-AS is provided, which is suitable for assisting an unmanned aerial vehicle UAV to perform a serving radio zone reselection. The UAV is connected to a cellular network via a serving radio zone and is also associated with the UAV-AS. The UAV-AS is adapted to: receive a request for allocating a flight path for the UAV to use for traveling to a destination point; after allocating the flight path, determine a list of radio zones suitable as serving radio zones along the allocated flight path; and provide the list of radio zones to the requester to assist the UAV in performing a serving radio zone reselection.

[0014] According to a further exemplary aspect of the invention, an unmanned aerial vehicle (UAV) is provided, which is suitable for performing a serving radio zone reselection. The UAV is connected to a cellular network via a serving radio zone and is also associated with a UAV application server (UAV-AS). The UAV is suitable for: receiving a request to travel to a destination point; after a flight path has been allocated, receiving from the UAV-AS (100) a list of radio zones suitable as serving radio zones along the allocated flight path; and while travelling along the allocated flight path, performing a serving radio zone reselection to a radio zone from the list of radio zones in order to maintain connection with the cellular network.

[0015] According to another exemplary aspect of the present invention, a system is provided, which is suitable for providing auxiliary information from a UAV application server UAV-AS to an unmanned aerial vehicle UAV to perform a serving radio zone reselection. The UAV is connected to a cellular network via a serving radio zone and is also associated with the UAV-AS. The system includes the UAV-AS and one or more UAVs.

[0016] A computer program product is also provided, which includes program code portions to perform any of the steps of the method proposed herein when executed on one or more processors. The computer program product can be stored on a computer readable recording medium such as a semiconductor / flash memory, a DVD, etc. The computer program product can also be provided for downloading via a communication connection.

[0017] The foregoing and other objects, features and advantages of the present invention will become more apparent in the following detailed description of the embodiments of the present invention as illustrated in the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Further characteristics and advantages of the present invention will become more apparent from the detailed description of particular but not exclusive embodiments thereof, illustrated by way of non-limiting example in the accompanying drawings, in which:

[0019] Figure 1 A diagram illustrating the radio area reachability situation of a ground based UE compared to a UAV is shown;

[0020] Figure 2 A diagram showing a UAV flight path scenario when traveling from A to B across several radio zone coverage areas;

[0021] Figure 3 A block diagram is shown for serving radio zone reselection in a UAV when traveling from an origin point to a destination point;

[0022] Figure 4A first block diagram in a UAV-AS is shown for receiving measurement reports from a UAV while driving and maintaining a database;

[0023] Figure 5 A second block diagram in a UAV-AS is shown for assisting a UAV in performing radio zone reselection while driving;

[0024] Figure 6 An exemplary composition of a computing unit configured to execute UAV-AS according to the present disclosure is shown;

[0025] Figure 7 An exemplary composition of a computing unit configured to execute a UAV according to the present disclosure is shown;

[0026] Figure 8 An exemplary modular functional composition of a computing unit configured to execute a UAV-AS according to the present disclosure is shown;

[0027] Fig. 9 An exemplary modular functional composition of a computing unit configured to perform a better UAV according to the present disclosure is shown;

[0028] Fig.10 An exemplary cellular network architecture for LTE including UAVs and UAV-ASs that may be used in accordance with the present disclosure is shown;

[0029] Fig.11 An exemplary cellular network architecture for 5G including UAVs and UAV-ASs that may be used in accordance with the present disclosure is shown. DETAILED DESCRIPTION

[0030] In the following, systems, methods, nodes and computer programs for a UAV to perform serving radio area reselection while driving and for a UAV-AS to assist a UAV in performing serving radio area reselection are described in more detail.

[0031] In the following description, for purposes of explanation and not limitation, specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent to those skilled in the art that the present disclosure may be practiced in other implementations that depart from these specific details. For example, although the following implementations will be described for LTE and 5G architectures, it will be understood that the present disclosure will not be limited to these architectures, and the techniques presented herein may also be practiced using other cellular network architectures. A cellular network may be a wireless network that uses radio-based communications toward its clients.

[0032] Those skilled in the art will also understand that the steps, services and functions described herein below may be implemented using separate hardware circuits, using software operating in conjunction with a programmed microprocessor or general purpose computer, using one or more application specific integrated circuits (ASICs), and / or using one or more digital signal processors (DSPs). It will also be understood that when the present disclosure is described in terms of methods, it may also be embodied in one or more processors and one or more memories coupled to the one or more processors, wherein the one or more memories are encoded with one or more programs that, when executed by the one or more processors, perform the steps, services and functions disclosed herein.

[0033] In the context of this application, the term "unmanned aerial vehicle", or UAV for short, refers to an autonomous device or machine that can move around in any given environment. UAV is considered a synonym for "drone" or "mobile robot". Mobile robots have the ability to move around in their environment, so they are not fixed to one physical location. In contrast, industrial robots usually consist of an articulated arm (multi-linked manipulator) and a gripper assembly (or end effector) that is attached to a fixed surface when operating. Mobile robots can be classified according to the environment in which they move:

[0034] -Land or domestic robots are often called unmanned ground vehicles. They are most commonly wheeled or tracked, but also include legged robots with two or more legs (humanoid or animal or insect-like).

[0035] -Aerial robots are often called unmanned aerial vehicles (UAVs).

[0036] -Underwater robots are often called autonomous underwater vehicles or unmanned submarines.

[0037] -Surface-based mobile robots are often called unmanned marine vehicles.

[0038] The vehicles listed above are types of vehicles that move automatically on a programmed or commanded path or towards a commanded geographic location / destination and therefore do not require human piloting or can also be remotely operated and controlled. The vehicle can also carry human passengers, but none of these passengers will participate in operating the vehicle. The vehicle may include a pilot or driver, but the vehicle will be operated in an autonomous mobile mode, in which the driver or pilot is separated from the actual operation task.

[0039] These vehicles can be operated in the air, on land, underground, in the sea and inland waters, in space and even on other planets / asteroids. These vehicles have their own engines, which are jet engines, thrusters, wheels, tracks, propellers or hovering thrusters and gears. The vehicles have the ability to exchange data wirelessly with each other and / or with a control base (such as UAV-AS). This data exchange can be achieved using a ground-based cellular or wireless communication network. Such a communication network can be operated by a mobile operator, and therefore the data communication service of the communication network can be used to communicate between the UAV and the control ground station.

[0040] UAVs can be deployed to transport goods, such as package delivery from a dealership or store to the end customer. They can also be used for postal services, mail delivery or surveillance missions.

[0041] In the context of this application, the term "cellular network" may refer to a wireless communication network, or in particular to a collection of nodes or entities, related transmission links, and associated management required for running a (communication) service, such as a wireless telephone service or a wireless packet transmission service. Depending on the service, different node types or entities may be utilized to implement the service. A network operator owns a cellular network and provides implemented services to its subscribers. Typical components of a wireless / cellular communication network are a radio access network RAN ​​(such as 2G, GSM, 3G, WCDMA, CDMA, LTE, 5G, NR, WLAN, Wi-Fi), a mobile backhaul network, and a core network (such as a GPRS core, EPC, 5G core).

[0042] Within the context of this application, the term "radio area" may denote an area covered by a radio base station. That may be a radio cell, or a collection of neighboring radio cells, location areas, routing areas, or tracking areas. In this context, a "serving radio area" is a radio area via which a UE or UAV is connected to a cellular network. If roaming outside the reach of a serving radio area, the UE / UAV must switch to a new radio area, whereby the new radio area becomes a new serving radio area. Therefore, the UE / UAV must reselect the serving radio area. Typically, the selection of a new serving radio area is under control and is therefore triggered by the cellular network. In order for the cellular network to be able to trigger reselection, preferably before the radio strength of the serving radio area becomes too weak, the UE / UAV periodically sends a radio strength or radio quality report on the range of radio areas currently seen by it.

[0043] In the context of the present application, the terms "starting point", "destination point" refer to the geographical point where the UAV can start or land respectively. Therefore, the term refers to any geographical point suitable for serving as the starting point of the UAV movement or as the destination point of such movement. Such a starting point or destination point is generally suitable for determining the movement path between these points. For example, if the UAV is used to deliver mail, the starting point can be a mail delivery center that collects mail centrally for distribution, and the destination point can be the recipient of such mail for the delivery subject. Alternatively, in the case of direct delivery from the sender to the recipient, the starting point can also be the originator of such mail. Usually, the landing point can be used as a starting point or as a destination point.

[0044] Within the context of this application, the term "flight path" refers to the path that a UAV travels between an origin and a destination point. In its simplest form, a flight path is a straight line between an origin and a destination point. However, in practice, a flight path may be more complex, for example if the flight path touches a so-called no-fly zone, requiring the UAV to detour around such an area. Traffic density or weather conditions may be other reasons for not using a straight flight path. In order to coordinate the flights of UAVs within a certain geographical area, local authorities may define certain flight policies, access policies or certain flight path segment definitions. Such flight policies are usually issued by an authorized (e.g. government) office / agency that is responsible for saving and controlling the use of UAVs in that area (flight safety authority).

[0045] Such a geographical region is characterized in that the applicable flight policies and the associated flight path segment definitions are stored in an application server AS and thus made accessible to anyone deploying a UAV in the region. The AS may be physically located in the region, or may be centralized (instantiated) somewhere in a remote / central data center (e.g. in the "cloud"), or may be implemented by a virtual network function. Even though the AS (or AS instance) may be far away from the geographical serving region, the geographical serving region will still be bound to one (logical) AS (instance), so the AS can be queried to obtain access to the applicable information.

[0046] Typically, such an authorizing (e.g., government) office / agency makes autonomous decisions about local flight policies in accordance with local laws. Flight policies and associated flight path segment definitions may also include UAV categories (e.g., weight categories), dynamic policies (e.g., depending on the time of day or flight density in the area), or may take into account access priorities (e.g., premium delivery services, or emergency / disaster recovery services).

[0047] A geographical area may also consist of one or more sub-areas of a different nature. While a geographical service area is thus a legislative area (wherein flight policies apply), such sub-areas may be radio coverage areas used in cellular communication networks, such as tracking areas, radio cells, location areas, routing areas or segments of a grid or geo-fence defined by, for example, GPS coordinates.

[0048] Thus, a flight path may be derived from such a flight path definition, and the UAV-AS may be authorized to assign an appropriate flight path to a UAV for traveling from an origin point to a destination point.

[0049] refer to Figure 2 , which shows a diagram of a UAV flight path situation when traveling from a starting point A to a destination point B, thereby crossing the coverage areas of several radio zones 1 to 4.

[0050] The figure shows a method for assisting a UAV 10 in performing serving radio zone reselection. The UAV 10 is connected to a cellular network via a serving radio zone, and the UAV 10 is associated with a UAV-AS 100.

[0051] The UAV-AS 100 receives a request to allocate a flight path for the UAV 10 to use to travel to a destination point. Thus, the flight path may be from A to B, and as shown in this example, is crossing radio zones 1 to 4. These radio zones partially overlap, and due to the fact that the UAV 10 is traveling at a higher altitude, the visibility of these radio zones, and also the overlap, may be different than that experienced on the ground.

[0052] A request for the allocation of a flight path may be received from a UAV 10 or from an operator of the UAV 10. Such an operator may own and operate a fleet of UAVs to deliver the service, such as a mail delivery service or a surveillance service. The operator may request the allocation of such a flight path from the UAV-AS 100 by defining the current location "A" of the UAV 10 and also defining the planned destination "B" to which the UAV 10 is expected to travel. Alternatively, a request for the allocation of a flight path may also be sent by the UAV 10 itself. In this scenario, the UAV 10 may receive a command from the UAV operator to deliver the service to the destination "B". The UAV 10 will then be responsible for requesting a suitable flight path from the UAV-AS 100. In another alternative, the UAV 10 may select the appropriate next command from, for example, an available command pool maintained by the UAV operator.

[0053] The figure also shows a method for performing a serving radio zone reselection by the UAV 10. The UAV 10 is connected to a cellular network via a serving radio zone, and the UAV 10 is associated with the UAV-AS 100. The UAV 10 receives a request to travel to a destination point. Such a request may be received from an operator of the UAV 10. In a next step, after the UAV-AS 100 has assigned a flight path, the UAV 10 receives from the UAV-AS 100 a list of radio zones suitable as serving radio zones along the assigned flight path. When traveling along the assigned flight path, the UAV 10 then performs a serving radio zone reselection to a radio zone from the radio zone list in order to maintain connection with the cellular network.

[0054] After allocating the flight path, the UAV-AS 100 determines a list of radio zones suitable as serving radio zones along the allocated flight path. And finally, the UAV-AS 100 provides the list of radio zones to the requester to assist the UAV 10 in performing serving radio zone reselection. The requester may be the UAV 10 or the operator of the UAV 10.

[0055] Such a list of radio zones may be suitable for listing radio zones as serving radio zones in a sequence that is selected consecutively when traveling along the assigned flight path. Thus, instead of the list being a pool of radio zones suitable for selection by the UAV 10 when traveling along the assigned flight path, the list may be further structured by also indicating a sequence of radio zones that will be suitable for use in a specified order. For example, the radio zones may be structured as a linked list or simply listed in a consecutive order. This additional structure allows the UAV 10 to search for the indicated next radio zone for reselection, and if that radio zone is detected, reselection may be triggered by the UAV 10.

[0056] As another option above the continuous order of radio zones on the radio zone list, the radio zone list may further include one or more geographical points along the assigned flight path, where the UAV 10 may perform service radio zone reselection. As an example, this is shown in the figure as a small circle at certain points along the flight path. In order to further optimize reselection, the list may not only indicate the order in which the UAV 10 may reselect the service radio zone, but may also indicate the geographical points on the flight path in which the UAV 10 may perform reselection. Such reselection points may be, for example, GPS coordinates. In this scenario, the UAV 10 may determine the distance to the next reselection point and suspend any search for the next radio zone until it approaches the indicated reselection point. The UAV-AS 100 may optimize the arrangement of the reselection points. Within the current service radio zone, these reselection points should still be placed well enough to ensure good radio contact. The reselection process takes some time, and if the UAV 10 is traveling at a higher speed, it must avoid that the UAV 10 has left the service radio zone before completing the process. This problem is exacerbated as UAVs travel at higher speeds.

[0057] Furthermore, the reselection point should be placed well enough in the new radio zone so that radio contact is still ensured. In the example figure, the first reselection point is well placed between radio zone 1 and radio zone 3. Radio zone 1 will still be available for some time along the flight path. Radio zone 3 has been available for some time, and therefore a safe reselection is ensured even if the UAV 10 is flying at a higher speed.

[0058] When traveling along the assigned flight path, the determination of the radio zone list by the UAV-AS 100 may be based on radio quality measurement information of radio zones detectable by the UAV 10. Thus, when traveling along the assigned flight path, the UAV 10 may send a radio zone measurement report including information about the detected radio zones to the UAV-AS 100. The UAV-AS 100 may be receiving a radio zone measurement report including information about the detected radio zones from the UAV 10 traveling along the assigned flight path.

[0059] Such radio quality information may be based on the strength of the radio and / or an error rate determined based on previously received data. The information may include radio quality measurements at one or more points within the assigned flight path. Thus, the UAV 10 may measure the radio quality and report the measurements to the UAV-AS 100, which will receive the information and may use it to determine a list of suitable radio zones.

[0060] In an alternative, the information may include radio quality progress information for each detected radio zone along the assigned flight path, and the information is provided by the UAV 10 and received by the UAV-AS 100 after the UAV 10 has completed the assigned flight path. Thus, the UAV 10 may perform radio quality measurements continuously or at certain periodic intervals, and thereby generate a curve of radio quality per radio zone along the flight path. At the end of the flight path, the UAV 10 may provide the measurement curve to the UAV-AS 100 that receives the measurement curve. The UAV-AS 100 may utilize the measurement curve in order to determine a list of suitable radio zones. Having the radio quality curve available at hand, the UAV-AS 100 may accurately determine the best point for the UAV 10 to trigger reselection, even if the UAV is traveling at a higher speed.

[0061] As a supplement or alternative to the above-mentioned radio quality information, the UAV 10 may also record whether the reselection of the indicated radio area has failed. In this case, the UAV 10 may have received a list of radio areas suitable for reselection, but the UAV 10 will not be able to detect a specific radio area that appears on the list. This may be a situation when there is a failure in the radio access network of the cellular network. Alternatively, the radio area on the list may be detectable, but the subsequent reselection of the radio area may be failing in order to use the radio area as a service radio area. This may occur due to an error in the cellular network. In this case, when traveling along the assigned flight path, the UAV 10 can send information about the radio area that is found to be unsuitable as a target for reselection as a service radio area on the radio area list to the UAV-AS 100. The UAV-AS 100 can receive such information from the UAV 10. Based on such information, the UAV-AS 100 can avoid adding the radio area to the list of suitable radio areas generated in the future.

[0062] Additionally or alternatively, the UAV-AS 100 may receive information about changes in the availability of radio zones or about new radio zones from the operator of the cellular network. If the operator of the cellular network learns of a failure of its radio access network, he may inform the UAV-AS 100 of this. Furthermore, in the case where the operator of the cellular network establishes a new radio zone in the radio access network, dividing the radio zone into two or more smaller radio zones, this may be informed to the UAV-AS 100. In this case, if the radio zone list has changed while the UAV 10 is traveling along the assigned flight path, the UAV-AS 100 may provide the UAV 10 with the updated radio zone list. While traveling along the assigned flight path, the UAV 10 may receive the updated radio zone list and replace the currently stored radio zone list with the newly received list.

[0063] This updated radio zone list provided by the UAV-AS 100 to the UAV 10 may include only the radio zones ahead of the current location and direction of travel of the UAV 10. This may shorten the information to be provided to the UAV 10 and simplify the processing of the list by the UAV 10.

[0064] UAV-AS 100 can maintain a database of radio areas suitable as service radio areas, and may even be so for each predefined flight path. UAV-AS 10 can utilize radio quality reports received from UAV 10 or information about failed radio areas received from UAV 10 or cellular network operators to keep such database up to date. Such a database can even include a predetermined list of suitable radio areas for each flight path. For example, if the flight path from A to B is often used by UAV, UAV-AS 100 can once determine a suitable radio area list and store the list in the database for continuous use. If the information received from UAV 10 is about new information about the failed radio area of ​​the radio area change from the network operator, UAV-AS 100 can redetermine such a list. Due to the high altitude of the UAV flight path, the radio area quality report may also depend on weather conditions and / or the load in such radio areas (called "cell breathing", that is, the size of the radio cell depends on the load in the cell). Thus, the UAV-AS 100 may re-determine such a list at periodic time intervals or based on weather forecasts or current radio area load reports from network operators. Thus, the information stored in the database may be reused for further UAV flights.

[0065] Once the UAV 10 has determined that a reselection of a serving radio zone from the list of suitable radio zones is required towards a radio zone, for example, if a radio zone from the list of radio zones is detected while travelling along the assigned flight path, the UAV 10 may perform a serving radio zone reselection. Such a serving radio zone reselection includes the UAV 10 sending a radio zone measurement report to a cellular network, the cellular network including the detected radio zone, the measurement report may even include only the next radio zone as the only radio zone in the report. This radio zone measurement reported to the cellular network may cause the cellular network to trigger a radio zone reselection procedure towards the UAV 10 to reselect to the detected radio zone.

[0066] It is the responsibility of the cellular network to trigger the reselection. However, the UAV 10 provides radio measurement reports to the cellular network, and based on these measurements, the cellular network knows what radio areas the UAV 10 currently sees and how good they are. Therefore, if the UAV 10 only reports radio areas on the received list of suitable radio areas, the cellular network has no choice but to initiate a reselection process towards the UAV 10 to manipulate the UAV 10 to reselect to one of the reported radio areas.

[0067] However, if the UAV 10 reports only a single radio zone from the list to the cellular network, and reselection to that radio zone fails, the UAV 10 may attempt to reselect other detected radio zones from the list, or, as a last resort, fall back to the standard mechanism and report all detectable radio zones, thereby also reporting radio zones that are not on the list received by the UAV 10 from the UAV-AS 100. This fallback mechanism ensures that the UAV 10 will always eventually be reachable via the cellular network, allowing the UAV-AS 100 to recover control of the UAV 10 at any time.

[0068] While traveling along the assigned flight path, the UAV-AS 100 determines a list of suitable radio zones for use by the UAV 10. Such determination of the list of radio zones may include adding one or more radio zones to the list of radio zones that allow the UAV 10 to minimize the number of serving radio zone reselections while traveling along the assigned flight path. Due to traveling at a higher altitude, a radio zone may be visible for a longer duration than perceived by a ground-based UE. Thus, some intermediate radio zones may be skipped along the flight path if the next radio zone becomes accessible early enough.

[0069] exist Figure 2This principle is further explained in the example in . Radio zones 1 to 4 partially overlap. Therefore, when traveling along the assigned flight path, the UAV 10 can first detect radio zone 1. Then, for a short period of time, radio zone 3 may also become visible in addition to radio zone 1. Thereafter, radio zone 2 may also be detected in addition to radio zones 1 and 3. However, radio zones 1 and 2 will gradually disappear, and there is a short range in which only radio zone 3 will be reachable. Then, radio zone 4 is detected, and subsequently radio zone 3 will gradually disappear. Radio zone 4 is then the only radio zone that can be reached to the destination.

[0070] Therefore, a possible sequence of radio zone reselection could be (in shorthand format):

[0071] First alternative: 1 => 3 => 2 => 3 => 4.

[0072] Alternatively, the UAV may also perform a reselection sequence:

[0073] Second alternative: 1 => 2 => 3 => 4.

[0074] Finally, the UAV may also perform the following reselection sequence:

[0075] Third alternative: 1 => 3 => 4

[0076] The third alternative of the reselection sequence does clearly involve the fewest radio zones and requires only two reselections along the flight path, which is obviously the minimum number of serving radio zone reselections when travelling along the allocated flight path.

[0077] Alternatively or additionally, the UAV-AS may take into account information about the type or size of the radio area. The radio access network of a cellular network is typically designed to include so-called macro radio areas (macrocells), which are intended to cover larger areas ("covered" radio areas) and smaller radio areas (microcells), which cover hotspots where greater capacity is required, or where the radio of the macro radio area will be obscured due to obstacles. Macro radio base station antennas may have more exposed locations and / or transmit using higher power to achieve greater coverage. The operator of the cellular network may provide such information about the type / size of the radio area to the UAV-AS 100, or the UAV-AS 100 may derive such a classification from the radio quality measurement reports of the UAV 100. Thus, when determining the list of radio areas, the UAV-AS 100 may prioritize macro radio areas over micro radio areas.

[0078] Alternatively or additionally, determining the radio zone list may include determining whether the assigned flight path can be covered by a single radio zone, and if so, adding only that radio zone to the radio zone list. This step covers the scenario where the flight path will occur entirely within the coverage of one radio zone. This may be the case for short-range flights. For this case, no reselection may be required along the assigned flight path.

[0079] However, if the assigned flight path cannot be covered by a single radio zone, the UAV-AS 100 can determine a table of all permutations of radio zone combinations that cover the assigned flight path. In the above example, three alternative reselection sequences cover the entire flight path, so the UAV-AS 100 can build a table including these three permutations.

[0080] Finally, the UAV-AS 100 may add the radio zone combination to the radio zone list comprising the least number of different radio zones. As shown in the above example, this is clearly the case for the third alternative.

[0081] The determined list of radio zones is then provided from the UAV-AS 100 to the UAV 10. As described above, such determinations may also be performed periodically by the UAV-AS 100 and the results stored in a database.

[0082] refer to Figure 3 , which shows a block diagram for serving radio zone reselection in a UAV when traveling from an origin to a destination point. The UAV may correspond to the UAV 10 as shown in the previous figures.

[0083] If the UAV receives a request to travel to destination point B, the process starts at step 300. The request may also include starting point A, for example, if A is different from the current location of the UAV. Such a request may be received from the operator of the UAV. The request may include an assigned flight path to destination B.

[0084] In step 310, the UAV receives a list of radio zones along the assigned flight path that would be suitable for use as service areas when traveling along the assigned flight path. Such a list of radio zones may be received along with the assigned flight path from the UAV-AS, or the UAV may request such a list separately from the flight path assignment step.

[0085] The UAV may then initiate a flight mission toward destination B along the assigned flight route in step 320 .

[0086] While traveling along the assigned flight route, the UAV can monitor the radio environment continuously or at certain time intervals. For example, the radio areas on the list can be sorted in the order of continuous appearance along the flight path. Therefore, in such an example, the UAV can accurately know which radio area to scan. Therefore, in step 330, the UAV determines whether the next radio area on the list will be detectable and enter the reach of the UAV. If the next radio area is detected, then in step 340, the UAV sends a radio measurement report including only the radio area to the cellular network. Alternatively, if the UAV fails to detect the expected next radio area on the list, although the area should already be in the reach range, then in step 350, the UAV falls back to the normal radio area reporting mode that reports all detectable radio areas to the cellular network.

[0087] In step 360, the cellular network may trigger a serving radio zone reselection or handover process, causing the UAV to perform the reselection / handover. The target radio zone is set by the cellular network and is based on the radio measurement reports from the UAV. Thus, if the UAV has only reported a single radio zone from the list, this trigger from the cellular will reselect / handover to that radio zone. If the UAV has reported more than one radio zone to be in reach, the cellular network will decide the target radio zone.

[0088] In step 370, the UAV reports the radio quality measurements to the UAV-AS. Such reporting to the UAV-AS may be done at certain time intervals, flight distances, or when radio conditions change. Alternatively, while traveling along the assigned flight path, the UAV may report a radio quality progress report for each of the radio areas it sees. Such a progress curve may be reported at the end of the flight mission when destination B is reached or is about to be reached.

[0089] refer to Figure 4 , which shows a first block diagram of a UAV-AS for receiving measurement reports from a UAV while traveling and maintaining a database. The UAV-AS may correspond to the UAV-AS 100 as shown in the previous figures.

[0090] The process begins at step 400, where the UAV-AS receives reports from the UAV reporting on radio quality measurements while traveling along the assigned flight path. As described above, such reporting from the UAV to the UAV-AS may be done at certain time intervals, flight distances, or changes in radio conditions. Alternatively, while traveling along the assigned flight path, the UAV may report a radio quality progress report for each of the radio areas it sees. Such a progress curve may be reported at the end of the flight mission when reaching destination B.

[0091] In step 410, the UAV-AS stores the received radio quality measurement information in a database and thereby builds up knowledge of the radio environment along all flight paths. By continuously storing and updating information in the database, the UAV-AS has sufficient information readily available to determine a list of suitable radio zones along the flight path. The process of steps 400 and 410 ensures that the database is always up to date with the currently available radio zones and their current coverage.

[0092] refer to Figure 5 , which shows a second block diagram of a UAV-AS for assisting a UAV in performing radio zone reselection while driving. The UAV-AS may correspond to the UAV-AS 100 as shown in the previous figures.

[0093] The process begins at step 500, where the UAV receives a request to assign a flight path to destination B for use by the UAV. Such a request may originate from the operator of the UAV, or directly from the UAV selected for travel to destination B.

[0094] In step 510, the UAV-AS decides the flight path that the UAV should follow when traveling to destination B. The UAV-AS may also allocate capacity (flight slots) in the selected flight path. In such selection and allocation steps, the UAV-AS may utilize well-known algorithms, for example, by avoiding no-fly zones, selecting flight segments with sufficient space to handle the UAV, or by a combination of predefined flight path segments defined by local flight safety authorities.

[0095] In step 520 , the UAV-AS may determine a list of radio zones suitable for use as the serving radio zones along the flight path selected and assigned in step 510 .

[0096] As already described above, the UAV-AS can select a radio zone which allows the UAV to minimize the number of radio zone reselections when travelling along the assigned flight path towards the destination B.

[0097] Finally, the UAV-AS provides the determined radio zone list to the requester, and thus to the operator of the UAV, who can then forward it to the UAV, or directly to the UAV, in step 530. Such provision can be done together with information about the assigned flight path, or separately from such information.

[0098] refer to Figure 6, which shows an exemplary composition of a computing unit configured to execute a UAV-AS according to the present disclosure. The UAV-AS may correspond to the UAV-AS 100 as shown in the previous figures.

[0099] The computing unit 600 includes at least one processor 610 and at least one memory 620, wherein the at least one memory 620 contains instructions executable by the at least one processor 610, so that the computing unit 600 is operable to perform Figure 4 or Figure 5 The method steps described with reference to UAV-AS 100.

[0100] refer to Figure 7 , which shows an exemplary composition of a computing unit configured to execute a UAV according to the present disclosure. The UAV may correspond to the UAV 10 as shown in the previous figures.

[0101] The computing unit 700 includes at least one processor 710 and at least one memory 720, wherein the at least one memory 720 contains instructions executable by the at least one processor 710, so that the computing unit 700 is operable to perform Figure 3 The method steps described with reference to UAV 10.

[0102] It will be understood that computing units 600 and 700 may be physical computing units as well as virtualized computing units, such as virtual machines, for example. It will also be understood that computing units may not necessarily be implemented as independent computing units, but may be implemented as components that also reside on multiple distributed computing units and are implemented in software and / or hardware.

[0103] refer to Figure 8 , which shows an exemplary modular functional composition of a computing unit configured to execute a UAV-AS according to the present disclosure. The UAV-AS may correspond to the UAV-AS 100 as shown in the previous figures. The UAV-AS may include a transceiver module 810, a radio zone database 820, a radio zone list determination module 830, and a flight path determination module 840.

[0104] The transceiver module 810 may be adapted to perform reception and transmission of request / response messages, such as step 400, step 500, step 530, and any signaling messages related to assisting a UAV in performing serving radio area reselection.

[0105] The radio zone database 820 may be suitable for storing radio quality measurements received from the UAV when traveling along the assigned flight path. The radio quality measurements may be stored in a structured manner, for example, the measurements may be classified by measuring at a specific altitude per specific radio zone, geographic location, or UAV travel speed. This allows the UAV-AS to generate a three-dimensional picture of the coverage of the radio zone. When the situation changes or new information is received by the UAV-AS, the UAV-AS may keep the database up to date. The radio zone database 820 may be consulted about the latest status of the radio coverage of the radio zone in the area of ​​responsibility of the UAV-AS. The database may also store a determined radio zone list suitable for use along a given flight route, and the database may store such a list per a commonly used flight path or a predefined flight path. The database may be used by the determination module 830 to determine the radio zone list.

[0106] The determination module 830 for determining a list of serving radio zones may be adapted to determine such a list. To this end, the module may interact with the database 820 in order to provide a list of predetermined radio zones per flight path, or in order to cumulatively provide radio quality measurements per radio zone and per flight path. The determination module may determine the radio zones on the list so that the UAV can minimize the number of serving radio zone reselections or handovers.

[0107] The flight path determination module 840 may be adapted to determine, upon request, a flight path that best meets, for example, the request requirements in the area of ​​responsibility of the UAV-AS, the current flight density conditions, and the flight safety authorization requirements. Once a flight path is selected or determined, the module 840 may also allocate the flight path to the UAV by reserving capacity in the corresponding flight path. The results may also be stored, for example, in the database 820 for subsequent reuse.

[0108] refer to Fig. 9 , which shows an exemplary modular functional composition of a computing unit configured to execute a UAV according to the present disclosure. The UAV may correspond to the UAV 10 as shown in the previous figures. The UAV may include a transceiver module 910, a positioning module 920, a measurement and reporting module 930, and a manipulation module 940.

[0109] The transceiver module 910 may be adapted to perform reception and transmission of request / response messages, such as step 300, step 310, step 370, and any signaling messages related to performing serving radio zone reselection while driving.

[0110] The positioning module 920 can be adapted to determine the current own position of the UAV, e.g., GPS coordinates and altitude. The module can also determine its position based on triangulation of known radio transmitters and perceived radio strength. The module can also utilize the positioning services of the cellular network to determine its own position. Depending on the accuracy required, different positioning methods can be used to complement each other to verify the results or to shorten the determination time. The UAV can detect an approaching radio zone reselection point indicated in the radio zone list.

[0111] The measurement and reporting module 930 can be suitable for measuring the radio quality at the current position for each detected radio area, and collects radio quality measurements along the assigned flight path. The module 930 can utilize the transceiver module 910 to provide the responsible UAV-AS with a radio quality measurement at a specific / current position or a radio quality progress curve of the radio area. The module can also scan the radio area detectable from the UAV at the current position. In this way, the UAV can determine whether the radio area of ​​the radio area on the list or the next radio area on the list enters the reach range. The module can also be used to generate a radio strength measurement report to the cellular network. Based on such a measurement report, the cellular network can determine to initiate a service radio area reselection process towards the UAV.

[0112] The maneuvering module 940 may be adapted to control the movement of the UAV along a given flight path. The module may use data from the positioning module 920 and sensors to determine corrective actions for the UAV to move according to the requirements of the assigned flight path.

[0113] refer to Fig.10 , which shows an exemplary cellular network architecture for LTE including UAVs and UAV-AS, which can be used according to the present disclosure.

[0114] The radio coverage area of ​​the LTE network is based on tracking areas. In such an example, the geographic service area that the UAV-AS is responsible for can be constructed by one or more tracking areas of the LTE radio network. The UAV may include an LTE radio module (and some type of subscriber identity module SIM card) that is used to register the UAV into the packet core network of the network operator. Once registered, or as part of the registration process, the UAV may discover the UAV-AS responsible for the current geographic service. The normal mobility procedures of the packet core network are used to keep track of the mobility of the UAV. The architecture is described in more detail in this figure.

[0115] As a common LTE architecture, the architecture shown in the figure includes an eNodeB 1020, through which the UAV 1010 can be connected to a cellular network using an e-Uu interface. The eNodeB 1020 is connected to a mobility management entity MME 1000 for control plane support using an S1-MME interface, and is connected to a packet data network gateway PDN GW 1030 for user plane support (i.e., for user data delivery) using an S1-U interface. The MME 1000 is in turn connected to a home subscriber service HSS 1040 via an S6a interface, which contains user-related and subscription-related information. Those skilled in the art will appreciate that the architecture shown in the figure corresponds to a simplified LTE architecture, in which only those components necessary for the purpose of illustrating the technology proposed herein are shown.

[0116] In addition to the common entities of the LTE network described above, the architecture shown in the figure also includes a UAV application server 1050 (denoted as "UAV-AS" in the figure) as part of the cellular communication network. The UAV-AS 1050 may correspond to the UAV-AS described with respect to the previous figures. The UAV-AS 1050 is connected to the PDN GW 1030 via an SGi interface and supports an external interface that allows the functionality of the UAV-AS 1050 to be accessed to entities outside the cellular communication network, such as, for example, entities accessing the UAV-AS 1050 from the Internet, or vice versa.

[0117] Using the SGi interface to the packet core network, the UAV-AS can communicate with the UAV and vice versa. This allows indicating flight strategies or corresponding actions to the UAV and receiving flight path information from the UAV in the UAV-AS. Via an interface with an external network (such as the Internet), the UAV-AS can retrieve and provide information from the operator of the UAV or can contact other UAV-AS of the hierarchical UAV-AS architecture.

[0118] refer to Fig.11 , which shows an exemplary cellular network architecture for 5G including UAVs and UAV-ASs, which can be used according to the present disclosure.

[0119] The architecture shown in this figure corresponds to Fig.105G variant of the described architecture. The basic principles for practicing the techniques presented in this article can be equally applied to the 5G architecture in this figure. Therefore, unnecessary repetitions will be omitted below. It should only be noted that the functions described above for eNodeB, MME, PDN GW and HSS can in this case be performed by the corresponding functions of the 5G architecture, namely, the radio access network RAN ​​1120, the access and mobility function AMF 1100, the user plane function UPF1130 and the user data management UDM 1140, respectively.

[0120] According to another embodiment, a computer program is provided. The computer program can be executed by the processor 610 or 710 of the above-mentioned entity UAV-AS or UAV, respectively, so that a method for performing service radio area reselection of the UAV while driving and a method for assisting the UAV-AS in performing service radio area reselection of the UAV can be executed or controlled, as described above with reference to Figure 3 , Figure 4 or Figure 5 By executing the computer program, the entity UAV-AS or UAV can be made to operate according to the above method.

[0121] The computer program may be embodied as computer code, such as computer code of a computer program product. The computer program product may be stored on a computer readable medium, such as a disk or a memory 620 or 720 of a UAV-AS or UAV, or may be configured as downloadable information.

[0122] One or more of the embodiments described above may achieve at least one of the following technical effects:

[0123] • Reduce the number of handovers or radio zone reselections on the flight path from location A to location B;

[0124] • Avoid unnecessary handovers or radio area reselection and minimize interference with the cellular network and also reduce signaling load;

[0125] • Allowing higher UAV travel speeds;

[0126] • The UAV-AS dynamically learns the radio area visibility at a specific altitude over time and makes dynamic use of this information;

[0127] • Reuse of existing network capabilities without impacting deployed cellular networks or 3GPP signaling procedure definitions;

[0128] •May be required by national flight management departments in the future;

[0129] Modifications and other embodiments of the disclosed invention will occur to those skilled in the art with the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it should be understood that the embodiments are not limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the present disclosure. Although specific terms may be employed herein, they are used only in a general and descriptive sense and not for the purpose of limitation.

Claims

1. A method for assisting an unmanned aerial vehicle (UAV) (10) in performing a serving radio zone reselection, the UAV (10) being connected to a cellular network via a serving radio zone and also being associated with a UAV application server (UAV-AS) (100), the method being performed by the UAV-AS (100) and comprising: receiving (500) a request to allocate a flight path for the UAV (10) to use for traveling to a destination point; After assigning the flight path, determining (520) a list of radio zones suitable as serving radio zones along the assigned flight path, wherein the list of radio zones lists the radio zones as serving radio zones in a sequence suitable for consecutive selection when traveling along the assigned flight path; and providing (530) the radio zone list to a requester to assist the UAV (10) in performing serving radio zone reselection, and The radio zone list further comprises one or more geographical points along the assigned flight path at which the UAV (10) is to perform serving radio zone reselection.

2. The method according to claim 1, wherein: The list of confirmed radio zones includes: One or more radio zones are added to the radio zone list, the one or more radio zones allowing the UAV (10) to minimize the number of serving radio zone reselections while traveling along the assigned flight path.

3. The method according to claim 1, wherein: Determining the radio zone list is based on radio quality measurement information of the radio zones detectable when travelling along the assigned flight path.

4. The method according to claim 1, wherein: The list of confirmed radio zones includes: determining whether the assigned flight path can be covered by a single radio zone, and if so, adding only this radio zone to the radio zone list; If the assigned flight path cannot be covered by a single radio zone, determining a permutation table of radio zone combinations covering the assigned flight path; and The radio zone combination is added to the radio zone list comprising the least number of different radio zones.

5. The method according to claim 1, wherein: The UAV-AS (100) maintains (410) a database of radio zones suitable as service radio zones for each predefined flight path.

6. The method according to claim 1, further comprising: A radio area measurement report is received (400) from a UAV (10) travelling along the assigned flight path, the radio area measurement report including information about detected radio areas.

7. The method according to claim 6, wherein: The information includes radio quality measurements at one or more points within the assigned flight path.

8. The method according to claim 6, wherein: The information includes radio quality progress information along the assigned flight path for each detected radio area, and the information is received after the UAV (10) has completed the assigned flight path.

9. The method according to claim 1, further comprising: Information is received from the UAV (10) travelling along the assigned flight path regarding radio zones found by the UAV (10) on the radio zone list to be unsuitable for reselection as serving radio zones.

10. The method according to claim 1, further comprising: Information about changes in availability of radio zones or about new radio zones is received from the operator of the cellular network.

11. The method according to claim 1, further comprising: If the radio zone list has changed while the UAV (10) is traveling along the assigned flight path, the updated radio zone list is provided to the UAV (10).

12. The method according to claim 11, wherein: The updated radio zone list provided to the UAV (10) includes only the radio zones ahead of the current position and driving direction of the UAV (10).

13. The method according to claim 1, wherein: The request for allocation of a flight path is received from the UAV (10) or from an operator of the UAV (10).

14. A method for performing serving radio zone reselection by an unmanned aerial vehicle (UAV) (10), the UAV (10) being connected to a cellular network via a serving radio zone and also being associated with a UAV application server (UAV-AS) (100), the method being performed by the UAV (10), comprising: Receiving (300) a request to travel to a destination point; receiving (520) from the UAV-AS (100) a list of radio zones suitable as serving radio zones along the assigned flight path after the flight path has been assigned, wherein the list of radio zones lists radio zones as serving radio zones in a sequence suitable for consecutive selection when travelling along the assigned flight path; performing (340) serving radio zone reselection to a radio zone from the radio zone list to maintain connection with the cellular network while traveling along the assigned flight path; sending, while travelling along the assigned flight path, information to the UAV-AS (100) about radio zones on the radio zone list that are found to be unsuitable as targets for reselection as serving radio zones, wherein the radio zone list also includes one or more geographical points along the assigned flight path at which the UAV (10) is to perform serving radio zone reselection; and An updated radio zone list is received while traveling along the assigned flight path, and a currently stored radio zone list is replaced with the newly received list.

15. The method according to claim 14, wherein: Performing service radio zone reselection includes: if a radio zone from the radio zone list is detected while traveling along the assigned flight path, sending (340) a radio zone measurement report to the cellular network, the cellular network including the detected radio zone, so that (360) the cellular network triggers a radio zone reselection process toward the UAV (10) to reselect to the detected radio zone.

16. The method according to claim 14, further comprising: While travelling along the assigned flight path, a radio area measurement report is sent to the UAV-AS (100), the radio area measurement report including information on the detected radio areas.

17. The method according to claim 16, wherein: The information includes radio quality measurements at one or more points within the assigned flight path.

18. The method according to claim 16, wherein: The information comprises radio quality progress information along the assigned flight path for each detected radio area and is transmitted after the UAV (10) has completed the assigned flight path.

19. An application server UAV-AS (100) adapted to assist an unmanned aerial vehicle UAV (10) in performing a serving radio zone reselection, the UAV (10) being connected to a cellular network via a serving radio zone and being associated with the UAV-AS (100), the UAV-AS (100) comprising at least one processor (610) and at least one memory (620), wherein the at least one processor (620) is adapted to: receiving a request to allocate a flight path for the UAV (10) to use in traveling to a destination point; After the flight path is assigned, a list of radio areas suitable as service radio areas along the assigned flight path is determined, wherein: The radio zone list lists the radio zones as serving radio zones in a sequence suitable for consecutive selection when travelling along the assigned flight path; as well as providing the radio zone list to a requester to assist the UAV (10) in performing serving radio zone reselection, and The radio zone list further comprises one or more geographical points along the assigned flight path at which the UAV (10) is to perform serving radio zone reselection.

20. The UAV-AS (100) of claim 19, wherein: The UAV-AS (100) is adapted to perform the method according to any one of claims 2 to 13.

21. An unmanned aerial vehicle (UAV) (10) adapted to perform serving radio zone reselection, the UAV (10) being connected to a cellular network via a serving radio zone and being further associated with a UAV application server (UAV-AS) (100), the UAV (10) comprising at least one processor (710) and at least one memory (720), wherein the at least one processor (710) is adapted to: receiving a request to travel to a destination point; After a flight path has been allocated, a list of radio zones suitable as service radio zones along the allocated flight path is received from the UAV-AS (100), wherein: The radio zone list lists the radio zones as serving radio zones in a sequence suitable for consecutive selection when travelling along the assigned flight path; performing a serving radio zone reselection to a radio zone from the radio zone list while travelling along the assigned flight path in order to maintain connection with the cellular network; while travelling along the assigned flight path, sending to the UAV-AS (100) information about radio zones on the radio zone list that are found to be unsuitable as targets for reselection as serving radio zones, wherein the radio zone list also includes one or more geographical points along the assigned flight path at which the UAV (10) is to perform serving radio zone reselection; as well as An updated radio zone list is received while traveling along the assigned flight path, and a currently stored radio zone list is replaced with the newly received list.

22. The UAV (10) of claim 21, wherein: The UAV (10) is adapted to perform the method according to any one of claims 15 to 18.

23. A system adapted to provide assistance information from a UAV application server UAV-AS (100) to an unmanned aerial vehicle UAV (10) in order to perform a serving radio zone reselection, the UAV (10) being connected to a cellular network via a serving radio zone and also being associated with the UAV-AS (100), the system comprising: The UAV-AS (100) according to claim 19 or 20; as well as One or more UAVs (10) according to claim 21 or 22.

24. A computer-readable storage medium having stored thereon a computer program comprising instructions which, when executed on at least one processor, cause the at least one processor to perform the method according to any one of claims 1 to 18.

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