WO2018019394A1

WO2018019394A1 - Method and system for causing a mobile device to travel based on a network condition

Info

Publication number: WO2018019394A1
Application number: PCT/EP2016/068260
Authority: WO
Inventors: Martti Johannes Moisio; Zexian Li; Mikko Aleksi Uusitalo; Wigard Jeroen; Istvan Zsolt Kovacs; Rafhael AMORIM
Original assignee: Nokia Technologies Oy
Priority date: 2016-07-29
Filing date: 2016-07-29
Publication date: 2018-02-01

Abstract

This specification describes a method comprising causing a mobile device to travel along trajectory between a first location and a second location, the trajectory being determined at least in part based on a network condition of a terrestrial radio network to which the mobile device is configured to connect.

Description

Method and System for Causing a Mobile Device to Travel Based on a Network Condition

Field

This specification relates generally to causing a mobile device to travel based on a network condition, and in particular but not exclusively to causing an unmanned aerial vehicle to travel along a trajectory.

Background

Autonomous vehicles such as autonomous cars are able to travel within limitations. Unmanned aerial vehicles (UAVs) are a growing category of autonomous vehicles. Autonomous vehicles may need network connectivity for a number of reasons. Indeed, connectivity may be required by law in some jurisdictions, especially for UAVs which do not have human "back up". Cellular radio coverage may be a candidate for radio connectivity to UAVs.

Summary

According to a first aspect, the specification describes a method comprising: causing a mobile device to travel along trajectory between a first location and a second location, the trajectory being determined at least in part based on a network condition of a terrestrial radio network to which the mobile device is configured to connect.

The network condition may comprise a measure of path loss between the mobile device and a network base station.

The network condition may comprise a measure of quality of a network cell serving the mobile device and of the nearest cells.

The network condition may comprise cell load per cell.

The network condition may comprise network handover settings. The network condition may comprise interference. The network condition may comprise a number of handovers or reselections required along a trajectory between the first location and the second location.

The method may further comprise providing the mobile device with flight control information for setting the trajectory.

The mobile device may be moveable in three dimensions.

The mobile device may be an unmanned aerial vehicle.

The method may further comprise: providing the mobile device with flight control information configured to cause the mobile device to follow an updated trajectory, or configured to cause the mobile device to terminate its travel along the trajectory. The method may further comprise: providing the mobile device with an orientation relative to a network base station determined based on a network condition.

The method may further comprise: causing the mobile device to rotate on an axis based on the updated orientation.

The method may further comprise: providing the mobile device with information relating to excluded zones, and causing the trajectory of the mobile device to be determined such that the trajectory does not pass through the excluded zones. The method may further comprise: providing the mobile device with information relating to preferred zones, and causing the trajectory of the mobile device to be determined such that the trajectory passes through the preferred zones.

The trajectory may be determined by a coordination function provided by the mobile device and/or the network.

The coordination function may be at least partially embedded in the mobile device. The coordination function may be provided entirely at the mobile device. The coordination function may be provided entirely at the network. The coordination function may be distributed between the network and the mobile device in a client-server relationship.

The method may further comprise: receiving at the coordination function planned trajectory information, geo-location coordinates, and velocity information of nearby mobile devices.

The method may further comprise: determining the trajectory based at least in part on the trajectory information, geo-location coordinates and velocity information of the nearby mobile devices.

The method may further comprise: building a 3D radio coverage map based on the information received from nearby mobile devices including the geo-location coordinates and cell IDs of the cells serving each respective mobile device and, optionally, the cell IDs of nearby cells.

The method may further comprise: determining which cells are crossed by the trajectory of the mobile device. The method may further comprise: determining an alternative trajectory based on at least one of cell congestion, number of cell crossings and cell handover properties.

The method may further comprise: receiving signal strength measurement for one or more cells; and executing, for each of the one or more cells, a 3D radio search and prediction algorithm based on a typical 3D antenna pattern for a corresponding detected frequency band, a statistical signal propagation loss model, and a measured cell transmission power level.

The method may further comprise: determining a cell antenna orientation based on the 3D radio search and prediction algorithm.

The method may further comprise: determining channel quality expected to be experienced along the trajectory of the mobile device based on trajectory information and the 3D radio search and prediction algorithm; and one or more of: determining an alternative trajectory to reduce handover and/ or radio failure occurrence and/ or to increase signal reception level based on the determined channel quality, causing the mobile device to connect to a network base station based on quality, and causing the mobile device to modify data rates based on the expected channel quality.

The method may further comprise: causing the mobile device to upload broadband data at locations along the trajectory determined based on signal strength.

The method may further comprise: causing a propulsion of the mobile device to be adjusted based at least in part on the determined trajectory. According to a second aspect , the specification describes a computer program comprising machine readable instructions that when executed by computing apparatus causes it to perform any method as described with reference to the first aspect.

According to a third aspect, the specification describes an apparatus configured to perform any method as described with reference to the first aspect.

According to a fourth aspect, the specification describes an apparatus comprising: at least one processor; and at least one memory including computer program code, which when executed by the at least one processor, causes the apparatus to perform a method comprising: causing a mobile device to travel along trajectory between a first location and a second location, the trajectory being determined at least in part based on a network condition of a terrestrial radio network to which the mobile device is configured to connect.

The network condition may comprise a measure of quality of a network cell serving the mobile device and of the nearest cells. The network condition may comprise cell load per cell.

The network condition may comprise network handover settings.

The network condition may comprise interference. The network condition may comprise a number of handovers or reselections required along a trajectory between the first location and the second location.

The computer program code when executed, may cause the apparatus to perform: providing the mobile device with flight control information for setting the trajectory.

The mobile device may be moveable in three dimensions.

The mobile device may be an unmanned aerial vehicle.

The computer program code when executed may cause the apparatus to perform: providing the mobile device with flight control information configured to cause the mobile device to follow an updated trajectory, or configured to cause the mobile device to terminate its travel along the trajectory.

The computer program code when executed may cause the apparatus to perform: providing the mobile device with an orientation relative to a network base station determined based on a network condition. The computer program code when executed may cause the apparatus to perform: causing the mobile device to rotate on an axis based on the updated orientation.

The computer program code when executed may cause the apparatus to perform: providing the mobile device with information relating to excluded zones, and causing the trajectory of the mobile device to be determined such that the trajectory does not pass through the excluded zones.

The computer program code when executed may cause the apparatus to perform: providing the mobile device with information relating to preferred zones, and causing the trajectory of the mobile device to be determined such that the trajectory passes through the preferred zones.

The coordination function may be at least partially embedded in the mobile device. The coordination function may be provided entirely at the mobile device. The coordination function may be provided entirely at the network.

The coordination function may be distributed between the network and the mobile device in a client-server relationship.

The computer program code when executed may cause the apparatus to perform: receiving at the coordination function planned trajectory information, geo-location coordinates, and velocity information of nearby mobile devices.

The computer program code when executed may cause the apparatus to perform: determining the trajectory based at least in part on the trajectory information, geo- location coordinates and velocity information of the nearby mobile devices. The computer program code when executed may cause the apparatus to perform: building a 3D radio coverage map based on the information received from nearby mobile devices including the geo-location coordinates and cell IDs of the cells serving each respective mobile device and, optionally, the cell IDs of nearby cells. The computer program code when executed may cause the apparatus to perform: determining which cells are crossed by the trajectory of the mobile device. The computer program code when executed may cause the apparatus to perform: determining an alternative trajectory based on at least one of cell congestion, number of cell crossings and cell handover properties.

The computer program code when executed may cause the apparatus to perform: receiving signal strength measurement for one or more cells; and executing, for each of the one or more cells, a 3D radio search and prediction algorithm based on a typical 3D antenna pattern for a corresponding detected frequency band, a statistical signal propagation loss model, and a measured cell transmission power level.

The computer program code when executed may cause the apparatus to perform: determining a cell antenna orientation based on the 3D radio search and prediction algorithm. The computer program code when executed may cause the apparatus to perform:

determining channel quality expected to be experienced along the trajectory of the mobile device based on trajectory information and the 3D radio search and prediction algorithm; and one or more of: determining an alternative trajectory to reduce handover and/or radio failure occurrence and/or to increase signal reception level based on the determined channel quality, causing the mobile device to connect to a network base station based on quality, and causing the mobile device to modify data rates based on the expected channel quality. The computer program code when executed may cause the apparatus to perform:

causing the mobile device to upload broadband data at locations along the trajectory determined based on signal strength.

The computer program code when executed may cause the apparatus to perform:

causing a propulsion of the mobile device to be adjusted based at least in part on the determined trajectory.

According to a fifth aspect, the specification describes a computer-readable medium having computer-readable code stored thereon, the computer-readable code, when executed by at least one processor, cause performance of at least: causing a mobile device to travel along trajectory between a first location and a second location, the trajectory being determined at least in part based on a network condition of a terrestrial radio network to which the mobile device is configured to connect. Brief Description of the Figures

Figure 1 is a schematic illustration of a system for controlling the trajectory of a mobile device according to embodiments of this specification;

Figure 2 is an illustration of a determined trajectory taking network conditions into account, as provided by embodiments of this specification;

Figure 3 is schematic illustration of signals transmitted between the network and the mobile device according to embodiments of this specification;

Figure 4 is a flow chart illustrating the steps performed by a coordination function which determines alternative trajectories of the mobile device, according to

embodiments of this specification;

Figure 5 is a flow chart illustrating steps involved in causing the mobile device to adopt a new trajectory, according to embodiments of this specification; Figure 6 illustrates the use of a 3D radio search and predict algorithm to predict the network conditions at a point along the trajectory, according to embodiments of this specification;

Figure 7 illustrates communication between an application layer of the mobile device and a traffic controller, according to embodiments of this specification;

Figure 8 is a flow chart illustrating the steps performed by an application layer of the mobile device, according to embodiments of this specification;

Figure 9 is a schematic illustration of an example configuration of a UAV, according to embodiments of this specification; and

Figure 10 illustrates a computer-readable memory medium upon which computer readable code may be stored, according to embodiments of this specification.

Detailed Description of Embodiments

In the description and drawings, like reference numerals may refer to like elements throughout.

Figure 1 is a schematic illustration of system 1 for controlling a mobile device 10. The examples described herein relate to controlling an unmanned aerial vehicle (UAV), also commonly known as a "drone".

In the example of Figure 1, system 1 provides for control of a mobile device 10. The mobile device 10 is configured to travel along a trajectory from a first location to a second location. The system 1 further includes a terrestrial network 12, configured to communicate bi-directionally with the mobile device 10. In the examples described herein, the terrestrial network 12 is a cellular radio access network, such as a 3GPP system and may comprise any of 2G, 3G, 4G, 5G, or it may be a Wi-Fi network.

However, as will be appreciated, the terrestrial network 12 may be any kind of suitable radio network with ground-based transceivers. The network 12 may include a number of base stations 20 which can communicate with the mobile device 10. The

communication between the network 12 and the mobile device 10 may take place via network communication unit 42 of the mobile device 10. The communication unit 42 comprises at least one transceiver 170 configured to send and receive signals to and from the network 12. The information communicated between the network 12 and the mobile device 10 relates to, for example, radio resource control information communicated by the network 12, and information relating to radio measurements measured by the mobile device 10. The radio measurements may include measurements of a cellular air interface and may include, for example, radio path loss between the mobile device 10 and the nearest base stations 20. The radio measurements may relate to the signal quality. Such measurements relating to signal quality may any one of reference signal received quality (RSRP), reference signal received power (RSRP), received signal strength indicator (RSSI), received signal code power (RSCP), and EcNo (the received energy per chip / power density in the band, equivalent to RSCP/RSSI). The radio measurements may also include bit error rate (BER) and packet error rate (PER))of the serving cell and of the nearest cells. Information may also include data indicating the location, such as geo-location coordinates (e.g. GPS coordinates), of the mobile device 10. This information is sent to the network 12 by the mobile device 10 or determined by the radio network 12 based on data sent by the mobile device 10. In the example of Figure 1, the system 1 further may comprise a traffic controller 14 configured to communicate bi-directionally with the mobile device 10. The traffic controller 14 may communicate with the mobile device 10, routed via the network 12, or may form part of the network 12. The information communicated between the traffic controller 14 and the mobile device 10 may include flight control information communicated by the traffic controller 14. It may also include location information such as geo-location coordinates (e.g. GPS coordinates) of the mobile device 10. The flight control information may include information for setting the trajectory of the mobile device 10. The flight control information may include information for updating the trajectory with any changes. The flight control information may include information causing the mobile device 10 to land, that is to become rested on the ground or a platform, or otherwise terminate its transit along the trajectory. The traffic controller 14 may store information relating to the trajectory of the mobile device 10. The traffic controller 14 may also plan the trajectory of the mobile device 10. Additionally, the traffic controller 14 may approve planned trajectories according to any relevant traffic control considerations.

Trajectory coordination by the traffic controller 14 is based on location and trajectory information which is available to the traffic controller 14 relating to mobile devices 10 such as UAVs. When following a trajectory, a mobile device 10 such as a UAV moves in three dimensions (3D). Such a mobile device 10 is also able to rotate about any axis. A mobile device such as a UAV is not restricted by roads or lanes in the same way as road vehicles, and so has more freedom of movement in 3D. The freedom of movement in 3D also means that the mobile device 10 experiences the channel conditions of a 3D radio environment. The 3D radio environment is determined by factors which include, but are not limited to, movement of the mobile device relative to the network base stations 20 including the angle of the antenna relative to the network base stations 20, 3D antenna radiation patterns, and the frequency band(s) used by the mobile device 10.

To maintain connectivity between the cellular network 12 and the mobile device 10, several handovers or reselections are likely to be performed, both intra-frequency and inter-frequency. Inter-operator handovers may also be required when considering radio control traffic. All these handover procedure involve radio signalling, and place a load on the network 12. The load is higher when the number of mobile devices 10 is large. Every handover comes with a risk of failure, and so this may lower the connection reliability, and may also increase latency of message delivery resulting from the communication path. The similarities between handover and reselection will be understood by the skilled person. In the following, we refer primarily to handover. However, it will be understood that references to handover are references to handover or reselection if the context so permits. In order to reduce the extent by which the connectivity or network performance is deteriorated during transit of mobile device 10 along its trajectory, the system 1 is configured to determine a trajectory based at least in part on a network condition of the network 12. The determination of the new trajectory may be performed by a coordination function 16. In the example depicted in Figure 1, the coordination function 16 may form part of the network 12, part of the traffic controller 14, or it may be part of a separate unit. The coordination function 16 may be provided as an application executed on a server or other computer, or distributed across plural computers. The coordination function 16 may be at least partially embodied in the mobile device, for example in an application layer 40. The coordination function 16 may alternatively be provided entirely at the application layer 40 of the mobile device 10. The coordination function may alternatively be provided entirely at the network 12. In one example, the coordination function 16 is distributed between the network and the mobile device 10. The coordination function 16 makes use of information relating to the planned trajectory, the velocity, and the geo-location coordinates of the mobile device 10, information relating to the cell serving the mobile device and the neighbouring cells having the strongest signal, radio traffic load information per cell (reported as current load by the network 12 or predicted for example based on historical data), interference sources and radio cell coverage areas per cell. Radio cell coverage areas may be pre- calculated or estimated based on a 3D coverage map.

In some embodiments, the coordination function 16 periodically receives from the network 12 information relating to measurements taken by the mobile device 10. The measurements taken by the mobile device 10 may be a measurement of parameters relating to a cellular air interface, and may include any of, but not limited to:

measurements of path loss between the mobile device 10 and the base station 20 of the serving cell and a number of neighbouring cells; and quality of the serving cell and of a number of neighbour cells. Additionally, the coordination function 16 may periodically receive from the network information relating to the geo-location coordinates of the mobile device 10. Additionally, the coordination function 16 may periodically receive, from the network, information relating to cell load on a per cell basis. This may be, for example, split into different quality of service (QoS) classes, if this information is available.

The coordination function 16 may periodically receive from the traffic controller 14 information relating to planned trajectories per mobile device 10 communicating with the traffic controller 14. Additionally, the coordination function 16 may periodically receive from the traffic controller 14 information relating to geo-location coordinates if, for example, these coordinates are not available from the network 12. Additionally, the coordination function 16 may receive information relating to the velocity of the mobile device 10 periodically from the traffic controller 14.

The coordination function 16 may build a 3D network coverage map based on the geo- location coordinates from mobile devices 10 and their corresponding serving cell identifiers (IDs). This may also include the IDs of nearby cells. These measurements may be provided by test flights. Alternatively, the measurements may be collected by several mobile devices 10 travelling in given locations. Accordingly, the coordination function 16 may determine which cells are being crossed by the trajectory of the mobile device 10.

The coordination function 16 may be configured to determine if an initial trajectory of a mobile device passes through congested cells, and can propose a new trajectory which avoids the congested cells. In this context, a congested cell is a cell which is at or near to capacity in terms of the number of devices connected to the cell and/or the traffic communicated between the devices 10 and the base station 20.

Alternatively or additionally, the coordination function 16 may propose modifying the handover settings of the mobile device 10 for certain cells, in order to avoid frequent handovers or reselections (for instance by setting certain cells on the route to a forbidden cell for the mobile device 10). For example, this may include an example in which the coordination function 16 may determine an alternative trajectory which passes through fewer cells. This results in fewer handovers between cells being performed, and thus the likelihood of handover failure may be reduced. In other embodiments, modifying the handover settings may include modifying the trigger time for handover. For example, the trigger time may be modified to adjust the time at which the mobile device switches from one cells to another and may for example be modified to enter a less-congested cell earlier, enter a cell earlier in view of the mobile device's speed at the entering point of the trajectory, or setting the trigger time later to avoid entry into a second cell altogether when entry into a third cell is imminent.

A new trajectory may also be determined based on the spectrum available in a given direction, for example in order to reach millimetre or centimetre wave spectrum for higher capacity. Determining the trajectory to traverse known locations of higher capacity cells generally may alleviate the load on lower capacity cells as well as provide better connectivity for the mobile device

The coordination function 16 may provide radio conditions predicted to be experienced by the mobile device 10. The radio conditions may be determined by the network communication unit 42 located at the mobile device 10. For example, the coordination function 16 may estimate prior to, at commencement of, or in near to real-time during travel the number of handovers required for a given trajectory. The coordination function 16 may determine alternative trajectories with reduced numbers of handovers. The coordination function 16 may determine when to send or upload mobile broadband data related to the mobile device trajectory 10. The coordination function 16 may determine how to improve radio switching, selection or handover. For example, the coordination function 16 can set particular cells to be forbidden cells, or may increase the trigger time to avoid handover to particular cells which the coordination function 16 determines should be avoided. In this way, the coordination function 16 controls the mobile device 10 to reduce negative effects of the mobile device's 10 mobility on the network connection quality.

In some embodiments, in order to predict the network conditions to be experienced by the mobile device, the coordination function 16 may determine the current geo-location coordinates of the mobile device 10. The coordination function 16 may also determine the geo-location coordinates of the surrounding cell towers for the network, measured by the mobile device. The coordination function 16 may determine the down-link (DL) reference signal received power (RSRP) of a number of the strongest detected cells. For example, this may include determining the DL RSRP of the strongest 3, 4, or 5 strongest detected cells, or any other relevant number of cells. The coordination function 16 may also determine the transmit power of the detected cells.

To predict the network conditions to be experienced by the mobile device, the coordination function 16 may make use of typical 3D antenna patterns for a

corresponding frequency band detected by the mobile device 10. The coordination function may use a statistical signal propagation loss model relevant for the mobile device 10 locations, frequency band, and class of radio environment.

In one example, for each detected base station, the coordination function 16 may be configured to execute a "3D radio search and prediction algorithm" using the 3D antenna pattern, the statistical signal propagation loss model, the transmit power of the base station described above in order to determine a matching cell antenna orientation in terms of azimuth and tilt values. The coordination function 16 may use the trajectory information and the velocity of the mobile device 10 and the determined azimuth and tilt values for each of the detected cells to predict the radio channel quality to be experienced by the mobile device 10. On this basis, the coordination function 16 may adjust the trajectory based on the determined cell azimuth and tilt values for each of the detected cells. For example, the trajectory may be adjusted in order to reduce the radio handover, and/or radio failure occurrence likelihood. Alternatively or additionally, the trajectory may be adjusted in order to increase the signal reception level for the currently connected radio cell.

The coordination function 16 may also adjust the rotation of the mobile device 10 along any of its own axes, in order to get a better angle of arrival or angle of departure to the radio signals (i.e. the mobile device 10 may be instructed to travel with a certain posture with respect to some transmitters or receivers). For example, the mobile device 10 may travel such that a main lobe of the device's antenna 120 is directed towards a specific desired cell or away from a specific cell causing interference. In one example, the mobile device 10 may travel such that the antenna maintains a fixed orientation towards a specific cell. In one example, the coordination function 16 may be configured to adjust the behaviour of the mobile device 10 based on the predicted radio channel quality. For example, the behaviour of the mobile device 10 may be adjusted in order to mitigate the effects of the geo-mobility of the mobile device 10. The behaviour of the mobile device 10 may be adjusted so that the mobile device 10 is configured to switch among its available radio channels to use the best predicted radio channel. The behaviour of the mobile device 10 may be adjusted to adapt the application layer 40 data rates, in order to match the estimated radio channel conditions. The behaviour of the mobile device 10 may be adjusted to pre-empt upload of mobile device 10 broadband data, for example to make use of a strong RSRP level, and for example, to avoid low radio link bitrates.

The network 12 and mobile device 10 may exchange information with each other relating to the "3D radio search and prediction algorithm". For example, the network 12 may be configured to switch on or off the functionality of the application layer 40. The exchanged information may relate to alternative trajectories determined by the mobile device. For example, the application layer 40 may propose an alternative trajectory to the network 12. Alternatively or additionally, the network 12 may provide the mobile device 10 with a new or updated trajectory. The exchanged information may relate to radio cell history. For example, the network 12 may provide the mobile device 10 with information relating to typical network load per cell, or information relating to handover failure rate measured for given areas by other mobile devices 10 travelling in the given areas along similar trajectories.

For any new trajectory proposed by the coordination function 16 and/or the application layer 40, the traffic controller 14 may be configured to determine whether the proposed trajectory is acceptable based on traffic control considerations. The traffic control considerations may include, but are not limited to, any non-fly zones, or the battery power remaining in the mobile device 10.

If the traffic controller 14 accepts the proposed trajectory, then the trajectory of the mobile device 14 is updated accordingly. If the traffic controller 14 does not accept the proposed trajectory, the traffic controller 14 may not update the trajectory of the mobile device, such that the mobile device continues to travel along its initial trajectory.

Alternatively, if the traffic controller 14 does not accept the proposed trajectory, the traffic controller may adjust the proposed trajectory in order to satisfy the traffic control requirements, and update the mobile device 10 accordingly.

In response to an updated trajectory being received from the traffic controller 14 or from the coordination function 16, the mobile device 10 is configured to adapt its propulsion using a propulsion mechanism such as a motor 131. Alternatively or additionally, the mobile device 10 may be configured to follow the new trajectory using a steering mechanism such as a propeller 130.

Figure 2 illustrates an example of a trajectory of a mobile device 10 which is determined based on a network condition of the network 12 to which the mobile device 10 is configured to connect, compared to a trajectory determined without taking network conditions into account. In this example, trajectories are determined between a start location 22 and an end location 24. A simple trajectory 26a which is determined without taking into account the network conditions of the cells forming part of the network is depicted by the dashed line. The system 1 determines, for the planned trajectory, which radio cells are crossed by the trajectory. While the mobile device travels along the trajectory 26a, at point x, the mobile device is connected to base station 20a, but receives strong interference from base station 20c. Beamforming, e.g. from 5G base stations, may cause particularly strong interference. The system 1 determines an alternative trajectory 26b, indicated by the solid line, to avoid interference, or to avoid causing interference to other wireless communications. The alternative trajectory 26b is communicated to the mobile device 10. The mobile device 10 is then controlled to follow the alternative trajectory 26b and thus is caused to take a trajectory along which interference is reduced. For example, the trajectory may be determined such that the mobile device 10 does not travel within a predetermined distance of point x, where the distance is set to be sufficient to avoid interference from base station 20c.

It will be appreciated that the trajectory may be determined based on any relevant network condition of cells belonging to a network, including, but not limited to the network conditions described herein.

Figure 3 illustrates an example of the signalling which may occur between the network 12 and the mobile device 10, according to embodiments.

The network 12 may provide the mobile device 10 with a "path update" message. Here, an update to the trajectory of the mobile device 10 is provided to the mobile device 10. The path update message may include information relating only to the relative change in the trajectory. For example, the path update message may include instructions to increase the altitude of the mobile device 10 by 5 meters. The path update message may include other parameters which include, but are not limited to, instructions that the command is valid only for a given timeframe, or only within a given geographical area or volume. In another example, the network 12 may provide the mobile device 10 with a "new path" message. In such an example, the mobile device 10 is provided with instructions to follow a new trajectory. For example, the mobile device 10 may be provided with a new set of 3D waypoints, for example in order to avoid a source of interference, or to get better connection to its own cell. Alternatively or additionally, the network may provide the mobile device 10 with a "new exclusion/preference zone(s)" message. Here, the mobile device 10 may be provided with a list of new areas which the mobile device 10 should avoid. Alternatively, the mobile device may be provided with a list of new areas which may be preferred. The areas may be defined according to a set of 3D coordinates.

In response to a message received from the network, including each of the messages described above in relation to Figure 3, the mobile device 10 may be configured to respond to a received message by sending an ACK message acknowledging the receipt of the message from the network 12. The mobile device 10 may be further configured to update and follow the updated trajectory in accordance with the instructions received from the network.

In response to the path update, new path, or new exclusion/preference zone message received from the network, the mobile device 10 is configured to adapt its propulsion using a propulsion mechanism such as a motor 131. Alternatively or additionally, the mobile device 10 may be configured to follow the new trajectory using a steering mechanism such as a propeller 130. It will be appreciated that the signalling between the network 12 and the mobile device 10 may include Radio Access Network (RAN) level signalling.

Alternatively or additionally, the signalling may be between the traffic controller 14 and the mobile device 10 via the network 12.

Figure 4 is a flow chart illustrating various operations which may be performed by the coordination function 16.

In operation S100, the coordination function 16 may determine trajectory information regarding a flight of at least one mobile device 10 within a coverage area of at least one terrestrial cellular network 12. For example, the trajectory information may be provided to the coordination function 16 by the mobile device 10. Alternatively, the trajectory information may be provided to the coordination by the traffic controller 14. The coordination function 16 may store trajectory information of the mobile device 14. The coordination function 16 may also determine trajectory information relating to other mobile devices 10 in the area. The coordination function 16 may also determine information relating to the velocity of the mobile device 10 or any other mobile devices 10 in the area.

In operation S110, the coordination function 16 may determine at least one network condition of the network 12. For example, the coordination function 16 may determine at least one measurement of a cellular air interface. These measurements may include measurements obtained by at least one mobile device 10. As described above, such measurements may include at least one relating to path loss, quality of the serving cell and of a number of neighbour cells. The coordination function 16 may also receive the geo-location coordinates associated with the mobile device 10. The coordination function may also receive information regarding cell load per cell. The coordination function may also receive information regarding the location of cells, their coverage areas etc. This information may be received at the coordination function 16 from the network 12.

The coordination function 16 may determine the 3D radio coverage of the network 12. As discussed previously, this may be done by building a 3D radio map based on the received geo-location coordinates of the mobile devices 10 and their corresponding serving cell IDs, and may also be based on the cell IDs of nearby cells.

In operation S120, the coordination function may determine a trajectory. As previously discussed, the trajectory may be based at least in part on the determined network condition, for example based on the cell load or congestion, number of cell crossings, and/or cell handover settings. The trajectory may also be based at least in part on the determined trajectory information.

In operation S130, an indication for setting or updating the trajectory is transmitted towards the mobile device. It will be appreciated that if the coordination function is located entirely at the mobile device 10, then no transmission will be necessary, and the coordination function 16 will update the mobile device 10 to follow the updated trajectory. However, in the case that the coordination function 16 is provided separately to the mobile device 10, the indication for setting or updating the trajectory may be transmitted to the mobile device 10 directly or indirectly. For example, the coordination function may provide the indication for setting or updating the mobile device 10 with the alternative trajectory to the traffic controller 14. Alternatively, the coordination function 16 may directly provide the mobile device 10 with information relating to the alternative trajectory, in order for the mobile device 10 to follow the alternative trajectory without seeking approval from the traffic controller 14·

In some examples, the mobile device 10 may provide information relating to an alternative trajectory determined at the application layer 40 of the mobile device 10 to the traffic controller 14 for approval. If the alternative trajectory is approved, an indication for setting or updating the trajectory may be provided to the mobile device 10 from the traffic controller 14.

In operation S140, the indication provided to the mobile device 10 causes the mobile device to adapt its propulsions and/or steering based at least in part on the determined trajectory.

Figure 5 is a flow chart illustrating various operations involved in causing the mobile device to adopt a new trajectory.

In operation S200, the mobile device 10 may determine at least one measurement of a cellular air interface comprised in a mobile device 10. The measurements may be determined by the application layer 40 or the network communication unit 42. The measurements may be determined by a coordination function 16 which is provided at least in part on the mobile device 10. In operation S210, the mobile device 10 may transmit a representation of the measurement(s) to a terrestrial cellular network 12. The cellular air interface may be connected to or camped on the cellular network 12.

In operation S220, the mobile device 10 may receive an indication of a flight trajectory based at least in part on the representation.

In operation S230, the mobile device 10 may be configured to cause its propulsion to be adjusted based at least in part on the indicated flight trajectory. The mobile device 10 may also be configured to cause its steering to be adapted based at least in part on the indicated flight trajectory. Figure 6 illustrates an embodiment in which the coordination function 16 is used to execute a "3D radio search and prediction algorithm" as described above with reference to Figure 1. In this example, the mobile device 10 may be configured to measure quality values (e.g. RSRP, RSSI values) corresponding to one cell or several different cells. However, the measurements may correspond to cells with transceivers located on the same site. The coordination function 16 may subsequently execute, for each of the cells, the 3D radio search and prediction algorithm based on the typical 3D antenna patterns, statistical signal propagation loss model, and associated cell transmit power level, as described above, such that the mobile device may determine the cell antenna orientations. The determined cell antenna orientations may be used to predict the quality of the received cells at a future location of the mobile device 10 along its trajectory. It may be appreciated that the 3D radio search and prediction algorithm may be performed on the basis of any other suitable number of measured quality values.

Figure 7 illustrates an example of the information exchange which may take place between the components of the system 1 including the application layer 40 of the mobile device 10. In this example, the coordination function 16 is partially embodied in the application layer 40 of the mobile device, and partially in the network 12, for example, using a client-server relationship. The application layer 40 may have read access to radio protocol parameters and measurements of the network communication unit 42, such as RSRP and reference signal received quality (RSRQ), which may be used in the 3D radio search and predict algorithm. However, it will be appreciated that the coordination function 16 may be provided entirely at the network 12, and may for example be provided at the traffic controller 14, or as part of a standalone unit configured to communicate with the traffic controller 14 and/or the mobile device 10 via the network 12.

Figure 8 is a flow chart illustration various operations which may be performed by the coordination function 16. In some examples, the operations may be performed entirely by the application layer 40. However, in other examples, at least some of the operations could alternatively or additionally be performed by a ground-based coordination function 16, e.g. in the traffic controller 14 or forming part of the network 12. In operation S300, the coordination function i6may determine the geo-location of the mobile device 10. The coordination function 16 may also determine the geo-location of base stations 20 detected by the mobile device. In operation S310, the application layer 40 may receive measurements of the signal strength from one cell or several cells nearest to the mobile device 10. As discussed previously, the application layer 40 may receive such measurements from the network communication unit 42. In operation S320, the coordination function 16 may execute a 3D radio search and prediction algorithm. As discussed previously, the algorithm may be based on typical 3D antenna patterns for corresponding detected frequencies, a statistical signal loss propagation model, and a measured cell transmission power level. In operation S330, the coordination function 16 may determine a matching cell or cells antenna orientation.

In operation S340, the coordination function 16 may determine the channel quality likely to be experienced by the mobile device, based on the trajectory information of the mobile device.

In operation S350, the coordination function 16 may determine an alternative trajectory based on the predicted channel quality. The trajectory may be determined in order to reduce handover failure occurrence likelihood, or to increase signal reception level, for example.

Figure 9 is a schematic diagram of an example configuration of a mobile device 10 such as described with reference to Figures 1 to 8. The mobile device 10 may comprise at least one sensor 110. The sensor may be, for example, a camera, such as an optical or an infrared camera. The sensor 110 may be configured to record images or other data captured by the sensor 110.

The mobile device 10 comprises at least one antenna 120 configured to emit and receive radio frequency signals to and from the network 12. In this way, the network 12 is able to communicate messages between the base stations 20 and the mobile device 10. The mobile device 10 additionally comprises at least one propulsion mechanism such as a motor 131, and a steering mechanism, such as a propeller 130. Accordingly, the mobile device 10 is able to adapt its propulsion and steering based on the determined trajectory being followed by the mobile device 10.

Optionally, the mobile device 10 may comprise landing hardware 140 configured to bring the mobile device 10 down to land from the air. The mobile device 10 further comprises at least one transceiver 170 configured to send and receive signals to and from the network 12.

The mobile device 10 may comprise memory 160 and processing circuitry 150. The memory 160 may comprise any combination of different types of memory. The memory may comprise one or more read-only memory (ROM) media and one or more random access memory (RAM) memory media. The mobile device 10 may further comprise one or more input interfaces which may be configured to receive signals from the network 12, and/or the traffic controller 14. The processing circuitry 150 may be configured to process the signals received by the input to determine an alternative trajectory and/or to control the mobile device 10 to follow an alternative trajectory. The mobile device 10 may further comprise one or more output interfaces configured for outputting measurements and/or other information to at least one of the network 12 and the traffic controller 14. The memory 160 described with reference to Figure 9 may have computer readable instructions stored thereon, which when executed by the processing circuitry 150 causes the processing circuitry 150 to cause performance of various ones of the operations described above. The processing circuitry 150 described above with reference to Figure 9 may be of any suitable composition and may include one or more processors of any suitable type or suitable combination of types. For example, the processing circuitry 150 may be a programmable processor that interprets computer program instructions and processes data. The processing circuitry 150 may include plural programmable processors. Alternatively, the processing circuitry 150 may be, for example, programmable hardware with embedded firmware. The processing circuitry 150 may be termed processing means. The processing circuitry 150 may alternatively or additionally include one or more Application Specific Integrated Circuits (ASICs). In some instances, processing circuitry 150 may be referred to as computing apparatus.

The processing circuitry 150 described with reference to Figure 9 is coupled to the memory 160 (or one or more storage devices) and is operable to read/write data to/from the memory. The memory may comprise a single memory unit or a plurality of memory units upon which the computer readable instructions (or code) is stored. For example, the memory 160 may comprise both volatile memory and non-volatile memory. For example, the computer readable instructions may be stored in the non- volatile memory and may be executed by the processing circuitry 150 using the volatile memory for temporary storage of data or data and instructions. Examples of volatile memory include RAM, DRAM, and SDRAM etc. Examples of non-volatile memory include ROM, PROM, EEPROM, flash memory, optical storage, magnetic storage, etc. The memories in general may be referred to as non-transitory computer readable memory media.

The term 'memory', in addition to covering memory comprising both non-volatile memory and volatile memory, may also cover one or more volatile memories only, one or more non-volatile memories only, or one or more volatile memories and one or more non-volatile memories.

The computer readable instructions described herein with reference to Figure 9 may be pre-programmed into the mobile device 10. Alternatively, the computer readable instructions may arrive at the mobile device 10 via an electromagnetic carrier signal or may be copied from a physical entity such as a computer program product, a memory device or a record medium such as a CD-ROM or DVD. The computer readable instructions may provide the logic and routines that enable the mobile device 10 to perform the functionalities described above. The combination of computer-readable instructions stored on memory (of any of the types described above) may be referred to as a computer program product.

Figure 10 illustrates an example of a computer-readable medium 900 with computer- readable instructions (code) stored thereon. The computer-readable instructions (code), when executed by a processor, may cause any one of or any combination of the operations described above to be performed. Where applicable, wireless communication capability of the mobile device 10 may be provided by a single integrated circuit. It may alternatively be provided by a set of integrated circuits (i.e. a chipset). The wireless communication capability may alternatively be provided by a hardwired, application-specific integrated circuit (ASIC). Communication between the components of the system may be provided using any suitable protocol, including but not limited to a 3GPP protocol.

As will be appreciated, the mobile device 10 described herein may include various hardware components which have may not been shown in the Figures since they may not have direct interaction with embodiments.

The features of the embodiments described above can provide improved performance compared to systems in which the features were not implemented. For instance, if the traffic controller 14 is not aware of the network 12 and the associated network conditions, the planned trajectory might in a hypothetical alternative to embodiments be determined without taking any relevant network conditions into account, which may result in poor connection between the network 12 and the mobile device 10, or poor network performance. Merely ensuring that a mobile device 10 has continuous connectivity is not as effective as the features of the embodiments described above.

In some cases, certain cells may provide worse connectivity for the mobile device 10 to the network 14, based on signal strength along the trajectory through a cell.

Additionally, mobile device 10 may cause interference to a cellular communication, and vice versa. Such cellular communications may relate to communications between the network and any User Equipment (UE) comprising a portable transceiver 170, and include, but are not limited to: communications between the network 12 and mobile phones, pagers, or any other kind of mobile computing device which is configured to connect to the network 12. Some or all of this can be avoided by using features of the embodiments as described above.

Embodiments may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. The software, application logic and/or hardware may reside on memory, or any computer media. In an example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a "memory" or "computer-readable medium" may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. Reference to, where relevant, "computer-readable storage medium", "computer program product", "tangibly embodied computer program" etc., or a "processor" or "processing circuitry" etc. should be understood to encompass not only computers having differing architectures such as single/multi -processor architectures and sequencers/parallel architectures, but also specialised circuits such as field

programmable gate arrays FPGA, application specific integrated circuits (ASICs), signal processing devices and other devices. References to computer program, instructions, code etc. should be understood to express software for a programmable processor firmware such as the programmable content of a hardware device as instructions for a processor or configured or configuration settings for a fixed function device, gate array, programmable logic device, etc.

As used in this application, the term 'circuitry' refers to all of the following: (a) hardware-only circuit implementations (such as implementations in only analogue and/or digital circuitry) and (b) to combinations of circuits and software (and/or firmware), such as (as applicable): (i) to a combination of processor(s) or (ii) to portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

This definition of 'circuitry' applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term "circuitry" would also cover, for example and if applicable to the particular claim element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in server, a cellular network device, or other network device. If desired, the different functions discussed herein may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined. Similarly, it will also be appreciated that the flow diagrams of Figures 4, 5 and 8 are examples only and that various operations depicted therein may be omitted, reordered and/or combined.

Although various aspects are set out in the independent claims, other aspects comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

As used herein, the term "mobile device" may cover, but is not limited to, unmanned aerial vehicles (UAVs), and any other kind of autonomous vehicle. It is also noted herein that while the above describes various examples, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the appended claims.

Claims

1. A method comprising:

causing a mobile device to travel along trajectory between a first location and a second location, the trajectory being determined at least in part based on a network condition of a terrestrial radio network to which the mobile device is configured to connect.

2. A method according claim 1, wherein the network condition comprises a measure of path loss between the mobile device and a network base station.

3. A method according to claim 1 or claim 2, wherein the network condition comprises a measure of quality of a network cell serving the mobile device and of the nearest cells.

4. A method according to any preceding claim, wherein the network condition comprises cell load per cell.

5. A method according to any preceding claim, wherein the network condition comprises network handover settings.

6. A method according to any preceding claim, wherein the network condition comprises interference.

7. A method according to any preceding claim, wherein the network condition comprises a number of handovers or reselections required along a trajectory between the first location and the second location.

8. A method according to any preceding claim, further comprising providing the mobile device with flight control information for setting the trajectory.

9. A method according to any preceding claim, wherein the mobile device is moveable in three dimensions.

10. A method according to any preceding claim, wherein the mobile device is an unmanned aerial vehicle.

11. A method according to any preceding claim, further comprising:

providing the mobile device with flight control information configured to cause the mobile device to follow an updated trajectory, or configured to cause the mobile device to terminate its travel along the trajectory.

12. A method according to any preceding claim, further comprising providing the mobile device with an orientation relative to a network base station determined based on a network condition.

13. A method according to claim 12, comprising causing the mobile device to rotate on an axis based on the updated orientation.

14. A method according to any preceding claim, further comprising providing the mobile device with information relating to excluded zones, and causing the trajectory of the mobile device to be determined such that the trajectory does not pass through the excluded zones.

15. A method according to any preceding claim, further comprising providing the mobile device with information relating to preferred zones, and causing the trajectory of the mobile device to be determined such that the trajectory passes through the preferred zones.

16. A method according to any preceding claim, wherein the trajectory is determined by a coordination function provided by the mobile device and/or the network.

17. A method according to claim 16, wherein the coordination function is at least partially embedded in the mobile device.

18. A method according to claim 16, wherein the coordination function is provided entirely at the mobile device.

19. A method according to claim 16, wherein the coordination function is provided entirely at the network.

20. A method according to claim 16, wherein the coordination function is distributed between the network and the mobile device in a client-server relationship.

21. A method according to any of claims 16 to 20, further comprising:

receiving at the coordination function planned trajectory information, geo- location coordinates, and velocity information of nearby mobile devices.

22. A method according to any of claims 16 to 20, further comprising:

determining the trajectory based at least in part on the trajectory information, geo-location coordinates and velocity information of the nearby mobile devices.

23. A method according to claim 22, further comprising:

building a 3D radio coverage map based on the information received from nearby mobile devices including the geo-location coordinates and cell IDs of the cells serving each respective mobile device and, optionally, the cell IDs of nearby cells.

24. A method according to claim 23, further comprising:

determining which cells are crossed by the trajectory of the mobile device.

25. A method according to claim 24, further comprising:

determining an alternative trajectory based on at least one of cell congestion, number of cell crossings and cell handover properties.

26. A method according to any preceding claim, further comprising:

receiving signal strength measurement for one or more cells; and

executing, for each of the one or more cells, a 3D radio search and prediction algorithm based on a typical 3D antenna pattern for a corresponding detected frequency band, a statistical signal propagation loss model, and a measured cell transmission power level.

27. A method according to claim 26, further comprising:

determining a cell antenna orientation based on the 3D radio search and prediction algorithm.

28. A method according to claim 26 or 27, further comprising: determining channel quality expected to be experienced along the trajectory of the mobile device based on trajectory information and the 3D radio search and prediction algorithm; and one or more of:

determining an alternative trajectory to reduce handover and/or radio failure occurrence and/or to increase signal reception level based on the determined channel quality,

causing the mobile device to connect to a network base station based on quality, and

causing the mobile device to modify data rates based on the expected channel quality.

29. A method according to claim 28, further comprising:

30. A method according to any preceding claim, further comprising:

31. A computer program comprising machine readable instructions that when executed by computing apparatus causes it to perform the method of any preceding claim.

32. Apparatus configured to perform the method of any of claims 1 to 30.

33. Apparatus comprising:

at least one processor; and

at least one memory including computer program code, which when executed by the at least one processor, causes the apparatus to perform a method comprising: causing a mobile device to travel along trajectory between a first location and a second location, the trajectory being determined at least in part based on a network condition of a terrestrial radio network to which the mobile device is configured to connect.

34. A computer-readable medium having computer-readable code stored thereon, the computer-readable code, when executed by at least one processor, cause performance of at least:

35. Apparatus comprising means for causing a mobile device to travel along a trajectory between a first location and a second location, the trajectory being determined at least in part based on a network condition of a terrestrial radio network to which the mobile device is configured to connect.