Methods and network devices for mobility management of unmanned aerial vehicles

1. A method, for use in a wireless communication device, for supporting mobility management of the wireless communication device in a wireless communication network comprising a plurality of radio network nodes, wherein one of the plurality of radio network nodes is a serving radio network node of the wireless communication device, the method comprising:

receiving, from the serving radio network node, a message including information associated with discovery signal transmission;

determining, based on the information, whether to transmit a discovery signal configured to support uplink-based mobility management of the wireless communication device by the wireless communication network, wherein the discovery signal is a sidelink communication signal; and

upon the determining being positive,

transmitting the discovery signal from the wireless communication device to one or more radio network nodes of the plurality of radio network nodes, wherein the discovery signal includes an identifier of the wireless communication device and an indication that the discovery signal is for supporting uplink-based mobility management of the wireless communication device based on measurements of the discovery signal by the one or more radio network nodes.

2. The method according to claim 1 , wherein the indication comprises at least one of: an information element, a flag comprised in the discovery signal, and a pre-defined format of the discovery signal.

3. The method according to claim 1 , wherein the discovery signal further comprises an identifier of the serving radio network node of the wireless communication device.

4. The method according to claim 1 , wherein the discovery signal is transmitted on radio resources that are also used for transmission of signals for use by functions other than mobility management.

5. The method according to claim 1 , wherein the discovery signal is transmitted on radio resources that are also is used by the wireless communication device for transmission of device to device, D2D, discovery signals and/or user plane data.

6. The method according to claim 1 , wherein the information associated with the transmission of the discovery signal comprises at least one of:

an instruction to the wireless communication device to transmit the discovery signal;

one or more criteria to be used by the wireless communication device when determining whether to transmit the discovery signal; and

information defining a repetition period and/or radio resources to use when transmitting the discovery signal.

7. The method according to claim 1 , wherein the determining comprises evaluating one or more criteria taking as input at least one of:

the number of radio network nodes being candidate target radio network nodes of the wireless communication device;

a speed of the wireless communication device; and

an aerial status of the wireless communication device.

8. A method, for use by a radio network node in a wireless communication network comprising a plurality of radio network nodes, for supporting uplink-based mobility management, the method comprising:

monitoring radio resources for discovery signals, wherein the discovery signals are device-to-device (D2D) discovery signals; and

upon identifying a discovery signal, transmitted by a wireless communication device to one or more radio network nodes of the plurality of radio network nodes, having an indication that the discovery signal is for supporting uplink-based mobility management, wherein the discovery signal is a D2D discovery signal,

reporting mobility data associated with the discovery signal to one or more other radio network nodes of the plurality of radio network nodes, wherein the mobility data is based on measurements of the discovery signal.

9. The method according to claim 8 , wherein the indication comprises at least one of: an information element, a flag comprised in the discovery signal, and a pre-defined format if the discovery signal.

10. The method according to claim 8 , wherein the discovery signal further comprises an identifier of a serving radio network node of the wireless communication device.

11. The method according to claim 8 , wherein the monitored radio resources are also used for transmission of signals for use by other functions than mobility management.

12. The method according to claim 8 , wherein the monitored radio resources are also used for transmission of Device-to-Device, D2D, discovery signals and/or user plan data, and wherein the monitoring comprises monitoring the determined radio resources for other signals.

13. The method according to claim 8 , further comprising:

receiving a message comprising information associated with a discovery signal transmitted by the wireless communication device; and

wherein the monitoring is performed based on at least a part of the received information.

14. The method according to claim 8 , wherein the mobility data comprises at least one of:

identity data defining wireless communication devices identified by the detected discovery signals,

measurement data corresponding to the detected discovery signals; and

measurement data corresponding to the detected discovery signals that fulfil a predefined criteria.

15. The method according to claim 13 , wherein the method further comprises:

determining resources that are used for transmission of discovery signals for use in mobility management.

16. The method according to claim 13 , wherein the determining comprises at least one of:

reading a predefined discovery signal configuration, and

receiving information defining the radio resources from a serving radio network node of the wireless communication device.

17. The method according to claim 13 , the method further comprising:

sending, to the serving radio network node a request asking the serving radio network node whether to report mobility data associated with the wireless communication device and

receiving, from the serving radio network node, a response acknowledging the request.

18. The method according to claim 13 , wherein the wireless communication network comprises a plurality of radio network nodes, the method further comprising:

sending, to one or more of the radio network nodes a request asking the whether to report mobility data associated with the wireless communication device.

19. A method, for use by a serving radio network node of a wireless communication device in a wireless communication network, wherein the wireless communication network comprises a plurality of radio network nodes, for managing mobility of the wireless communication device in the wireless communication network, the method comprising:

receiving, from one or more other network nodes of the plurality of network nodes, mobility data associated with measurements performed on a discovery signal transmitted by the wireless communication device to the one or more other network nodes for supporting uplink-based mobility management, wherein the discovery signal is a device-to-device (D2D) discovery signal and includes an indication that the discovery signal is for supporting uplink-based mobility management; and

performing mobility management of the wireless communication device based on the received mobility data.