Patent Description:
The present disclosure relates to the technical field of wireless communication, and in particular, to a method and a device for unmanned aerial vehicle handover, and a base station.

Unmanned Aerial Vehicles (UAVs) have been applied to some specific scenes to perform tasks such as aerial photography, unmanned detection and reconnaissance, measurement and surveying, highway surveying, city planning, ecological environmental monitoring, scientific investigation, oil exploration, aerial remote sensing, frontier patrol, forest fire prevention, disaster assessment, and the like.

In order to further expand the application range of the unmanned aerial vehicle, the 3rd Generation Partnership Project (3GPP) proposes a study that services meeting the requirements for the unmanned aerial vehicle provided by the cellular network become more standardized in a discussion of the Project of "enhanced support of unmanned aerial vehicles", and the cellular network is considered to determine a flight path of the unmanned aerial vehicle in advance, so that it is helpful to improve mobility of the unmanned aerial vehicle, for example, improving success rate and speed rate of handover. The related art does not provide a fast handover solution for the cellular network unmanned aerial vehicle. A new solution is required to implement fast handover of the unmanned aerial vehicle. <CIT> teaches apparatus and a method for enhancing connection mobility control for small cell networks, and <CIT> teaches handover and support for reliable handover in radio communication networks.

In order to solve the problems in the related art, embodiments of the present disclosure provide a method and a device for unmanned aerial vehicle handover, and a base station, so that the base station can determine a handover candidate base station based on a flight path of the unmanned aerial vehicle, and perform a handover preparation operation with the handover candidate base station in advance, thereby implementing fast handover to the handover candidate base station meeting conditions when the unmanned aerial vehicle needs to be handed over.

According to a first aspect of an embodiment of the present disclosure, a method for unmanned aerial vehicle handover applied to a source base station is provided as defined by claim <NUM>.

In one embodiment, determining whether a candidate base station that has completed the handover preparation exists among the base stations meeting the handover conditions, includes:.

In one embodiment, the method further includes:
determining the accessible base stations based on the flight path of the unmanned aerial vehicle and geographical location information of the base station.

In one embodiment, the method further includes:.

In one embodiment, performing the handover preparation operation for handing over to the base station in which the handover preparation operation is to be performed, and determining the base station that has successfully performed the handover preparation as the candidate base station that has completed the handover preparation, includes:.

In one embodiment, performing the handover preparation operation for handing over to the base station in which the handover preparation operation is to be performed, and determining the base station that has successfully performed the handover preparation as a candidate base station that has completed the handover preparation, includes:.

In one embodiment, the method further includes:
if the handover preparation failure signal is monitored, determining that the handover preparation fails.

In one embodiment, selecting a base station in which a handover preparation operation is to be performed from accessible base stations based on a flight speed and/or a flight altitude of the unmanned aerial vehicle, includes:.

In one embodiment, the method further includes:
when there is no candidate base station that has completed the handover preparation existing among the base stations meeting the handover conditions, sending a handover request signal to one of the base stations meeting the handover conditions.

According to a second aspect of an embodiment of the present disclosure, a device for unmanned aerial vehicle handover applied to a source base station is provided as defined by claim <NUM>.

In one embodiment, the first determination module includes:.

In one embodiment, the device further includes:
a second determination module configured to determine the accessible base stations based on the flight path of the unmanned aerial vehicle and the geographical location information of the base station.

In one embodiment, the device further includes:
a first acquisition module configured to interact the geographical location information of the base station with adjacent base stations, based on interfaces between the base stations; or acquire the geographical location information of each of the adjacent base stations from a core network equipment; or inquire the geographical location information of each of the adjacent base stations through a network management system of an operator.

In one embodiment, the handover preparation module includes:.

In one embodiment, the device further includes:
a third determination module configured to determine that the handover preparation fails if the handover preparation failure signaling is monitored.

In one embodiment, the base station selection module includes:.

In one embodiment, the device further includes:
a second handover module configured to send a handover request signaling to one of the base stations meeting the handover conditions when no candidate base station that has completed the handover preparation exists in the base stations meeting the handover conditions.

The technical solutions provided by the embodiments of the present disclosure may include beneficial effects below.

The source base station may determine whether a candidate base station that has completed handover preparation exists in the base stations meeting handover conditions while receiving a measurement report sent by the unmanned aerial vehicle, and if so, the unmanned aerial vehicle may be directly handed over to the candidate base station meeting the handover conditions, that is, a RRC connection reconfiguration signal may be directly sent to the unmanned aerial vehicle, to realize fast handover of the unmanned aerial vehicle to the candidate base station that has completed the handover preparation, and facilitate the base station for improving mobility of the unmanned aerial vehicle based on the flight path.

It should be understood that the foregoing general description and the following detailed description are merely exemplary and explanatory, and are not restrictive of the present disclosure.

The accompanying drawings, which are incorporated in and constitute part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the present disclosure.

Exemplary embodiments will be described in detail herein, examples of which are illustrated in the drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present disclosure. Instead, the embodiments are merely examples of devices and methods consistent with aspects of the present disclosure as described in detail in the appended claims.

In this disclosure, the unmanned aerial vehicle is a cellular network unmanned aerial vehicle accessed into a cellular network.

<FIG> is a flow chart showing a method for unmanned aerial vehicle handover according to an exemplary embodiment, and <FIG> is a scene diagram showing a method for unmanned aerial vehicle handover according to an exemplary embodiment, and the method for unmanned aerial vehicle handover can be applied to a source base station. As shown in <FIG>, the method for unmanned aerial vehicle handover includes the following steps <NUM>-<NUM>.

In step <NUM>, when base stations meeting handover conditions are determined based on a measurement report sent by an unmanned aerial vehicle, whether a candidate base station that has completed a handover preparation exists in the base stations meeting the handover conditions is determined.

In one embodiment, when the source base station receives the measurement report, the base station meeting the handover conditions may be determined based on the signal quality of each of the base stations, and if a signal received power is greater than -65dB, it shows that the base station has a very high coverage strength level at a position where the unmanned aerial vehicle is located, and is a base station meeting the handover conditions.

In one embodiment, the candidate base station that has completed handover preparation refers to a base station that has accepted a handover request initiated by the source base station. For example, if the source base station sends a HANDOVER REQUEST signal to the base station through an X2 interface connection and receives a HANDOVER REQUEST ACKNOWLEDGE signal from the base station, the base station may be determined as a candidate base station that has completed the handover preparation; or, the source base station sends HANDOVER REQUIRED signal to a Mobility Management Entity (MME) through an S1 interface, and monitors a HANDOVER COMMAND signal returned by the MME, so that the source base station may be determined as a candidate base station that has completed the handover preparation.

In one embodiment, the candidate base station may be recorded in a handover candidate base station set, and whether a candidate base station that has completed the handover preparation exists in the base stations meeting the handover conditions is determined by determining whether any of the base stations meeting the handover conditions exists in the handover candidate base station set. If any of the base stations meeting the handover conditions is located in the handover candidate base station set, the candidate base station that has completed handover preparation exists in the base stations meeting the handover conditions will be determined. For example, if the candidate base stations include a base station <NUM>, a base station <NUM>, and a base station <NUM>, and the base stations meeting the handover conditions include the base station <NUM>, it means that the base station <NUM> meeting the handover conditions is the candidate base station that has completed handover preparation.

In step <NUM>, when the candidate base station that has completed the handover preparation exists in the base stations meeting the handover conditions, the unmanned aerial vehicle is handed over to the candidate base station meeting the handover conditions.

In one embodiment, since the source base station has already sent a handover request to the candidate base station and monitored a signal for indicating that the handover preparation is successful, a Radio Resource Control (RRC) connection reconfiguration signal (i.e., RRCConnectionReconfiguration) signal may be directly sent to the unmanned aerial vehicle, indicating the unmanned aerial vehicle to be handed over to the candidate base station.

In an exemplary scene, as shown in <FIG>, in the scene shown in <FIG>, an unmanned aerial vehicle <NUM>, a source base station <NUM>, at least one candidate base station <NUM>, and the like are included, wherein after the source base station <NUM> acquires a flight path of the unmanned aerial vehicle <NUM>, it is possible to acquire geographical location information of each of the adjacent base stations, further to determine an accessible base station when the unmanned aerial vehicle <NUM> flies according to the flight path, and then to determine the base stations in which the handover preparation operation is to be performed based on a flight information of the unmanned aerial vehicle <NUM>, such as a flight speed and a flight altitude, to initiate a handover request to each of the base stations in which the handover preparation operation is to be performed to perform the handover preparation operation, and to determine the base station that has successfully performed the handover preparation as a candidate base station <NUM> that has completed the handover preparation, so that when the unmanned aerial vehicle reports the measurement report, if it is determined based on the measurement report that the candidate base station <NUM> that has completed the handover preparation exists in the base stations meeting the handover conditions, the unmanned aerial vehicle may be directly instructed to be quickly handed over to the candidate base station <NUM> meeting the handover conditions, and the mobility performance of the unmanned aerial vehicle <NUM> can be improved.

According to the above steps <NUM> to <NUM> of this embodiment, the source base station may determine whether the candidate base station that has completed handover preparation exists in the base stations meeting the handover conditions while receiving the measurement report sent by the unmanned aerial vehicle, and if so, the unmanned aerial vehicle may be directly handed over to the candidate base station meeting the handover conditions, that is, a RRC connection reconfiguration signal may be directly sent to the unmanned aerial vehicle, so as to realize fast handover of the unmanned aerial vehicle to the candidate base station that has completed the handover preparation, and facilitate the base station for improving mobility of the unmanned aerial vehicle based on the flight path.

Following embodiments are referred to, to specifically describe how to perform the unmanned aerial vehicle handover.

The technical solutions provided by the embodiments of the present disclosure will be described below with reference to the specific embodiments.

<FIG> is a flow chart showing another method for unmanned aerial vehicle handover according to an exemplary embodiment. In this embodiment, by using the above method provided by the embodiment of the present disclosure, exemplary description is provided as an example of how the source base station determining the candidate base station, as shown in <FIG>, the method includes the following steps.

In step <NUM>, an accessible base station is determined based on the flight path of the unmanned aerial vehicle and the geographical location information of the base station.

In one embodiment, the base station may acquire a flight path of the unmanned aerial vehicle from the core network equipment, and the flight path may be composed of a plurality of coordinate points or may also be indicated by a two-dimensional grid map.

In one embodiment, after the base station acquires the flight path of the unmanned aerial vehicle, it may determine which one of the adjacent base stations of the source base station is an accessible base station that may possibly serve for the unmanned aerial vehicle, based on the flight path of the unmanned aerial vehicle and the geographical location information of each of the base stations, for example, a position identified by the geographical location information of the base station through which the flight path of the unmanned aerial vehicle passes, or it may be determined that its coverage area includes a part of the flight path of the unmanned aerial vehicle based on the geographical location information of the adjacent base stations, or the like, that is, it may be determined which adjacent base stations are accessible base stations of the unmanned aerial vehicle, wherein next accessible base station of the unmanned aerial vehicle is not limited to one.

In one embodiment, the source base station of the adjacent base stations may acquire the geographical location information of each of the base stations in the following three manners.

A first manner: interacting the geographical location information of the base station with the adjacent base stations, based on interfaces between the base stations.

In one embodiment, the source base station may interact with the adjacent base stations through the interfaces between the base stations, such as an X2 interface, to determine the geographical location information with respect to each other.

A second manner: acquiring geographical location information of each of the adjacent base stations from a core network equipment.

In one embodiment, the source base station may send a request for acquiring the geographical location information of each of the adjacent base stations to the core network equipment through an S1 interface, thereby acquiring the geographical location information of each of the adjacent base station from the core network equipment.

A third manner: querying the geographical location information of each of the adjacent base stations through a network management system of an operator.

In one embodiment, the source base station may inquire as to the geographical location information of each of the adjacent base stations through an Operation, Administration and Maintenance (hereinafter referred as "OAM") system of an operator.

In step <NUM>, based on the flight speed and/or the flight altitude of the unmanned aerial vehicle, a base station in which the handover preparation operation is to be performed is selected from the accessible base stations, and the accessible base station is a base station that is accessible when the unmanned aerial vehicle flies according to the flight path.

In one embodiment, the flight speed and/or the flight altitude of the unmanned aerial vehicle may be reported to the source base station by the unmanned aerial vehicle after accessing to the source base station.

The source base station selects a first number of base stations in which the handover preparation operation is to be performed to perform the handover preparation operation in a forward direction of the unmanned aerial vehicle from the accessible base stations based on the flight speed of the unmanned aerial vehicle. A specific numerical value of the first number is associated with the flight speed. For example, if the flight speed of the unmanned aerial vehicle is faster, three base stations in the forward direction of the unmanned aerial vehicle may be selected as the base stations in which the handover preparation operation is to be performed; if the flight speed of the unmanned aerial vehicle is medium, two base stations in the forward direction of the unmanned aerial vehicle may be selected as the base stations in which the handover preparation operation is to be performed; and if the flight speed of the unmanned aerial vehicle is slower, one base station in the forward direction of the unmanned aerial vehicle may be selected as the base station in which the handover preparation operation is to be performed. A corresponding relationship of the flight speed to the number of base stations in which the handover preparation operation is to be performed may be set in advance, or may be calculated by the source base station.

In one embodiment, the source base station may select a second number of base stations in which the handover preparation operation is to be performed to perform the handover preparation operation in a forward direction of the unmanned aerial vehicle from the accessible base stations based on the flight altitude of the unmanned aerial vehicle. A specific numerical value of the second number is associated with the flight altitude. For example, if the flight altitude of the unmanned aerial vehicle is lower, one base station in the forward direction of the unmanned aerial vehicle may be selected as the base station in which the handover preparation operation is to be performed; if the flight altitude of the unmanned aerial vehicle is medium, two base stations in the forward direction of the unmanned aerial vehicle may be selected as base stations in which the handover preparation operation is to be performed; and if the flight altitude of the unmanned aerial vehicle is higher, two base stations in the forward direction of the unmanned aerial vehicle may be selected as the base stations in which the handover preparation operation is to be performed. The corresponding relationship of the flight altitude to the number of base stations in which the handover preparation operation is to be performed may be set in advance, or may be calculated by the source base station.

In one embodiment, the source base station may select a third number of base stations in which the handover preparation operation is to be performed to perform the handover preparation operation in the forward direction of the unmanned aerial vehicle from the accessible base stations based on the flight speed and the flight altitude of the unmanned aerial vehicle. A specific numerical value of the third number is associated with the flight altitude and the flight speed. For example, if the flight altitude of the unmanned aerial vehicle is higher and the flight speed thereof is faster, two base stations in the forward direction of the unmanned aerial vehicle may be selected as the base stations in which the handover preparation operation is to be performed, and if the flight altitude of the unmanned aerial vehicle is medium but the flight speed thereof is slower, one base station in the forward direction of the unmanned aerial vehicle may be selected as the base station in which the handover preparation operation is to be performed.

In one embodiment, the system may predetermine a criterion or algorithm to determine the number of base stations in which the handover preparation operation is to be performed based on the flight speed and/or flight altitude of the unmanned aerial vehicle.

In step <NUM>, the handover preparation operation for handing over to the base station in which the handover preparation operation is to be performed is performed, and the base station that has successfully performed the handover preparation is determined as a candidate base station that has completed the handover preparation.

In one embodiment, the method for performing the handover preparation operation can refer to the embodiments shown in <FIG>, which will not be described in detail herein.

In step <NUM>, when the base stations meeting the handover conditions are determined based on the measurement report sent by the unmanned aerial vehicle, whether the candidate base station that has completed the handover preparation exists in the base stations meeting the handover condition is determined. Step <NUM> is performed when the candidate base station that has completed the handover preparation exists in the base stations meeting the handover conditions, and step <NUM> is performed when no candidate base station that has completed the handover preparation exists in the base stations meeting the handover conditions.

In step <NUM>, the unmanned aerial vehicle is handed over to the candidate base station meeting the handover conditions.

In one embodiment, the descriptions of step <NUM> and step <NUM> can refer to the descriptions of step <NUM> and step <NUM> of the embodiment shown in <FIG>, which will not be described in detail herein.

In step <NUM>, a handover request signal is sent to one of the base stations meeting the handover condition.

In one embodiment, if no candidate base station that has completed handover preparation exists in the base stations meeting the handover conditions, a handover request signal may be sent to one base station with the highest signal quality in the base stations meeting the handover conditions, that is, when there is an X2 interface connection between the source base station and the base station with the highest signal quality, a HANDOVER REQUEST signal may be sent to the base station with the highest signal quality through the X2 interface connection; and when there is no X2 interface between the source base station and the base station with the highest signal quality, a HANDOVER REQUIRED signal is send to the MME through an S1 interface.

In this embodiment, three implementing manners in which the source base station acquires the geographical location information of other base stations are disclosed to facilitate the base station to flexibly determine the accessible base station when the unmanned aerial vehicle flies according to the flight path, and determine the number of base stations in which the handover preparation operation is to be performed based on the flight speed and/or the flight altitude of the unmanned aerial vehicle, so that it is helpful for the source base station to determine which base station to which the unmanned aerial vehicle may be handed over and thereby performing the handover preparation based on the actual flight information of the unmanned aerial vehicle, and the mobility of the unmanned aerial vehicle can be improved.

<FIG> is a flow chart showing still another method for unmanned aerial vehicle handover according to an exemplary embodiment. In this embodiment, by using the above method provided by the embodiment of the present disclosure, an exemplary description is provided as an example of how the source base station performs the handover preparation on the base station in which the handover preparation operation is to be performed, having an interface between the base stations.

In step <NUM>, if there is an X2 interface connection between the source base station and the base station in which the handover preparation operation is to be performed, a handover request signal is sent to the base station in which the handover preparation operation is to be performed through the X2 interface connection.

In step <NUM>, a response signal of the base station in which the handover preparation operation is to be performed is monitored, and step <NUM> or step <NUM> is performed.

In step <NUM>, if a handover request confirmation signal is monitored, it is determined that the handover preparation is successful, and the base station in which the handover preparation operation is to be performed is determined as the candidate base station that has completed the handover preparation.

In step <NUM>, if the handover preparation failure signal is monitored, it is determined that the handover preparation fails.

In one embodiment, in step <NUM> to step <NUM>, the source base station may directly send the HANDOVER REQUEST signal to the base station in which the handover preparation operation is to be performed through the X2 interface connection, and when a HANDOVER REQUEST ACKNOWLEDGE signal returned by the base station based on the handover request is monitored, it is determined that the handover preparation is successful, the base station that has successfully performed the handover preparation is determined as the candidate base station that has completed the handover preparation, and added to the handover candidate base station set. If a HANDOVER PREPARATION FAILURE is monitored, it is determined that the handover preparation fails.

In this embodiment, it discloses a method for implementing handover preparation and determining the candidate base station when there is an interface between the source base station and the base station in which the handover preparation operation is to be performed.

<FIG> is a flow chart showing yet another method for unmanned aerial vehicle handover according to an exemplary embodiment. In this embodiment, by using the above method provided by the embodiment of the present disclosure, an exemplary description will be provided as an example of how the source base station performs the handover preparation on the base station in which the handover preparation operation is to be performed, having an interface between base stations.

In step <NUM>, if there is no X2 interface connection between the source base station and the base station in which the handover preparation operation is to be performed, a handover required signal for handing over to the base station in which the handover preparation operation is to be performed is sent to a mobility management entity through an S1 interface.

In step <NUM>, a response signal returned by the mobility management entity based on the handover required signal is monitored, and step <NUM> or step <NUM> is performed.

In step <NUM>, if a command handover signaling is monitored, it is determined that the handover preparation is successful, and the base station in which the handover preparation operation is to be performed is determined as the candidate base station that has completed the handover preparation.

In one embodiment, in steps <NUM> to <NUM>, the source base station sends the HANDOVER REQUIRED signal to the MME through the S1 interface, the MME sends HANDOVER REQUEST signal to the base station in which the handover preparation operation is to be performed. the base station in which the handover preparation operation is to be performed sends a handover request response signal (HANDOVER REQUEST ACKNOWLEDGE signal) to the MME after the base station in which the handover preparation operation is to be performed allocates all necessary carrying resources for the unmanned aerial vehicle based on the HANDOVER REQUEST signal, and then the MME sends a HANDOVER COMMAND signal to the source base station, so that the source base station may determine that handover is successful, and determine the base station that has successfully performed the handover preparation as a candidate base station that has completed handover preparation, and add the candidate base station to the handover candidate base station set, and if the HANDOVER PREPARATION FAILURE signal is monitored, the handover preparation failure is determined.

In this embodiment, a method is disclosed for implementing handover preparation and determining the candidate base station when there is no interface between the source base station and the base station in which the handover preparation operation is to be performed.

<FIG> is a block diagram showing a device for unmanned aerial vehicle handover, which is applied to a source base station, according to an exemplary embodiment. As shown in <FIG>, the device for unmanned aerial vehicle handover includes:.

<FIG> is a block diagram showing another device for unmanned aerial vehicle handover according to an exemplary embodiment. As shown in <FIG>, and based on the embodiment shown in <FIG>, in an embodiment, the first determination module <NUM> includes:.

In one embodiment, the device further includes:.

In one embodiment, the device further includes:
a second determination module <NUM>, which is configured to determine the accessible base stations based on the flight path of the unmanned aerial vehicle and geographical location information of the base station.

In one embodiment, the device further includes:
a first acquisition <NUM> module, which is configured to interact the geographical location information of the base station with adjacent base stations, based on interfaces between the base stations; or acquire the geographical location information of each of the adjacent base stations from a core network equipment; or inquire the geographical location information of each of the adjacent base stations through a network management system of an operator.

<FIG> is a block diagram of still another device for unmanned aerial vehicle handover according to an exemplary embodiment. As shown in <FIG>, and based on the above embodiments shown in <FIG> and/or <FIG>, in an embodiment, the handover preparation module <NUM> includes:.

In one embodiment, the handover preparation module <NUM> includes:.

In one embodiment, the device further includes:
a third determination module <NUM>, which is configured to determine that the handover preparation fails if the handover preparation failure signal is monitored.

In one embodiment, the base station selection module <NUM> includes:.

In one embodiment, the device further includes:
a second handover module <NUM>, which is configured to send a handover request signal to one of the base stations meeting the handover conditions when no candidate base station that has completed the handover preparation exists in the base stations meeting the handover conditions.

With regard to the device in above embodiments, the specific manners in which each module performs operation have been described in detail in the embodiments related to the method, and will not be described in detail herein.

<FIG> is a block diagram showing a device applied to an unmanned aerial vehicle handover according to an exemplary embodiment. The device <NUM> may be provided as a base station or a core network equipment. Referring to <FIG>, the device <NUM> includes a processing assembly <NUM>, a wireless transmitting/receiving assembly <NUM>, an antenna assembly <NUM>, and a signal processing portion specific to a wireless interface, and the processing assembly <NUM> may further include one or more processors.

One of processors in the processing assembly <NUM> may be configured to perform the method for unmanned aerial vehicle handover described in the first aspect mentioned above.

Claim 1:
A method for unmanned aerial vehicle handover, wherein the method is applied to a source base station (<NUM>), wherein the method comprises:
selecting a base station in which a handover preparation operation is to be performed from accessible base stations based on a flight speed and/or a flight altitude of the unmanned aerial vehicle (<NUM>), wherein the accessible base station is a base station that the unmanned aerial vehicle (<NUM>) is able to access when flying according to a flight path;
performing the handover preparation operation for handing over to the base station in which the handover preparation operation is to be performed, and determining the base station that has successfully performed the handover preparation as a candidate base station (<NUM>) that has completed the handover preparation, in which the candidate base station (<NUM>) that has completed handover preparation refers to a base station that has accepted a handover request initiated by the source base station (<NUM>);
in response to base stations meeting handover conditions being determined based on a measurement report sent by an unmanned aerial vehicle (<NUM>), determining whether there is a candidate base station (<NUM>) that has completed a handover preparation existing among the base stations meeting the handover conditions; and
in response to the candidate base station (<NUM>) that has completed the handover preparation existing among the base stations meeting the handover conditions, handing over the unmanned aerial vehicle (<NUM>) to the candidate base station (<NUM>) meeting the handover conditions,
characterised in that,
the number of base stations in which the handover preparation operation is to be performed is increased with increased flight speed and/or flight altitude of the unmanned aerial vehicle.