Estimating terminal device localization data

1. A control method for a terminal device in a non-terrestrial cellular data communication network, the network comprising one or more airborne or spaceborne base stations moving along a flight trajectory, for connecting the terminal device to said network, the method comprising the following steps:

providing flight trajectory data for said one or more airborne or spaceborne base stations in a memory element of said terminal device;

providing terminal location data in the memory element of said terminal device;

using a data processing unit, determining at least one time slot during which a wireless communication channel between said terminal device and at least one of said one or more airborne or spaceborne base stations is estimated to be available, based on said flight trajectory data and on said terminal location data; and

using the data processing unit, scheduling a data reception or transmission between said terminal device and said at least one of said one or more airborne or spaceborne base stations during the determined time slot,

wherein providing terminal location data comprises the additional step of estimating the terminal location data based on detected properties of at least three signals received at the terminal device from at least three different positions taken by the one or more airborne or spaceborne base stations.

2. The method of claim 1 , wherein the at least three different positions correspond to three different flyovers of a specific one of the one or more airborne or spaceborne base stations over the terminal device.

3. The method of claim 1 , wherein said step of scheduling a data reception or transmission comprises switching the terminal device's state using said data processing unit from a first state, in which the terminal device is not capable of one or more of receiving data and transmitting data, to a second state, in which the terminal device is capable of one or more of receiving data and transmitting data using a data reception and transmission unit.

4. The method of claim 1 , wherein said step of providing flight trajectory data comprises, at said one or more airborne or spaceborne base stations, transmitting said flight trajectory data to said terminal device, and at the terminal device, using a data reception unit, receiving said flight trajectory data from said one or more airborne or spaceborne base stations through a respective wireless data communication channel.

5. The method of claim 1 , wherein said flight trajectory data comprises an identifier of said one or more airborne or spaceborne base stations, ephemeris data, altitude data, velocity data or any combination thereof.

6. The method of claim 1 , wherein said flight trajectory data comprises flight trajectory data describing the trajectories of a plurality of airborne or spaceborne base stations, together with their respective identifiers.

7. The method of claim 1 , wherein said terminal device computes, using said data processing unit and based on said flight trajectory data, estimate values for said one or more airborne or spaceborne base stations, comprising any of a future position, elevation, velocity, Doppler shift, Doppler drift, propagation delay, derivatives of said Doppler shift or propagation delay, or any combination thereof, and stores these estimate values in a memory element.

8. The method of claim 1 , wherein an airborne or spaceborne base station is estimated to be available, if its elevation above said terminal device is estimated to be above a predetermined elevation threshold value.

9. A control method for a terminal device in a non-terrestrial cellular data communication network, the network comprising at least one airborne or spaceborne base station moving along a flight trajectory, for connecting the terminal device to said network, the method comprising the following steps:

providing flight trajectory data for said least one airborne or spaceborne base station in a memory element of said terminal device;

providing terminal location data in the memory element of said terminal device;

using a data processing unit, determining at least one time slot during which a wireless communication channel between said terminal device and said least one airborne or spaceborne base station is estimated to be available, based on said flight trajectory data and on said terminal location data; and

using the data processing unit, scheduling a data reception or transmission between said terminal device and said least one airborne or spaceborne base station during the determined time slot,

wherein said at least one airborne or spaceborne base station is configured for transmitting a reference timing signal, and wherein the non-terrestrial cellular data communication network comprises a location service node storing information describing each airborne or spaceborne base station's respective flight trajectory,

wherein the step of providing terminal location data further comprises the following steps:

at the terminal device, accumulating over time the respective arrival times of the reference timing signal received from at least three different positions taken by at least one airborne or spaceborne base station;

computing, from said arrival times, at least two arrival time differences with respect to one reference arrival time;

transmitting, at the terminal device, said computed differences to said location service node, through one of said at least one airborne or spaceborne base station;

at said location service node, receiving said computed differences, computing a location estimate of said terminal device using said computed differences and said stored information describing each of the reference timing signal transmitting airborne or spaceborne base station's respective flight trajectory, and transmitting said location estimate to said terminal device, through one of said at least one airborne or spaceborne base station; and

at the terminal device, receiving said location estimate from one of said at least one airborne or spaceborne base station and storing it in the memory element.

10. The method of claim 9 , wherein the non-terrestrial cellular data communication network comprises a plurality of airborne or spaceborne base stations configured for transmitting a common synchronized reference timing signal, and wherein the step of accumulating said arrival times comprises the reception of the reference timing signal at the terminal device from at least two or three of said airborne or spaceborne base stations.

11. A terminal device for a non-terrestrial cellular data communication network, the terminal device comprising:

a data transmission unit,

a data reception unit,

a memory element for storing flight trajectory data of one or more airborne or spaceborne base stations of said network and for storing location data of the terminal device, and

a processing unit, wherein the processing unit is configured to:

determine at least one time slot during which a wireless communication channel between said terminal device and at least one of said one or more airborne or spaceborne base stations is estimated to be available, based on said flight trajectory data and on said terminal location data, and

schedule a data reception or transmission between said terminal device and said one or more airborne or spaceborne base stations during the determined time slot,

wherein the processing unit is further configured to estimate the terminal location data based on detected properties of at least three signals received at the terminal device from at least three different positions taken by the one or more airborne or spaceborne base stations.

12. The terminal device according to claim 11 , being a user equipment or a ground-based gateway node serving a plurality of user equipment.

13. The terminal device according to claim 11 , wherein the processing unit is further configured to schedule a data reception or transmission by switching the terminal device's state from a first state, in which the terminal device is not capable of one or more of receiving data and transmitting data, to a second state, in which the terminal device is capable of one or more of receiving data and transmitting data using the data transmission and reception units.

14. The terminal device according to claim 11 , wherein the processing unit is further configured to compute, based on said flight trajectory data, estimate values for said one or more airborne or spaceborne base stations, comprising any of a future position, elevation, velocity, Doppler shift, Doppler drift, propagation delay, derivatives of said Doppler shift or propagation delay, or any combination thereof, and store these estimate values in the memory element.

15. A non-terrestrial cellular data communication system comprising:

one or more airborne or spaceborne base stations each configured to transmit a reference timing signal,

a location service node storing information describing each airborne or spaceborne base station's respective flight trajectory, and

a terminal device comprising:

a data transmission unit,

a data reception unit,

a memory element for storing flight trajectory data of the one or more airborne or spaceborne base stations and for storing location data of the terminal device, and

a processing unit, wherein the processing unit is configured to:

determine at least one time slot during which a wireless communication channel between the terminal device and one of the one or more airborne or spaceborne base stations is estimated to be available, based on said flight trajectory data and on said terminal location data, and

schedule a data reception or transmission between said terminal device and said one or more airborne or spaceborne base stations during the determined at least one time slot,

accumulate over time the respective arrival times of the reference timing signal received from at least three different positions taken by at least one of the one or more airborne or spaceborne base stations;

compute, from said arrival times, at least two arrival time differences with respect to one reference arrival time; and

transmit the computed differences to the location service node, through one of the one or more airborne or spaceborne base stations,

wherein the location service node is configured to receive the computed differences, compute a location estimate of the terminal device using the computed differences and the stored information describing each of the reference timing signal transmitting airborne or spaceborne base station's respective flight trajectory, and transmit the location estimate to the terminal device, through one of the one or more airborne or spaceborne base stations;

wherein the terminal device is further configured to receive the location estimate from one of said one or more airborne or spaceborne base stations and store the location estimate in the memory element thereof.