Method and system for non-terrestrial cellular wireless communication networks
In an embodiment, a method for estimating a location of a terminal device of a non-terrestrial cellular data communication network, where the non-terrestrial cellular data communication network has one or more airborne or spaceborne base stations moving along a respective flight trajectory and the terminal device, includes the following. At the terminal device, performing a random wake-up and a blind acquisition of a carrier that is made available by a respective one of one or more airborne or spaceborne base stations to attach the terminal device to the non-terrestrial cellular data communication network; and, once the terminal device attaches successfully to the non-terrestrial cellular data communication network via one of the one or more base-stations, estimating terminal location data based on arrival times of at least three reference timing signals received at the terminal device from different positions taken by the one or more airborne or spaceborne base stations.
1. A method for estimating a location of a terminal device of a non-terrestrial cellular data communication network, the non-terrestrial cellular data communication network comprising one or more airborne or spaceborne base stations moving along a respective flight trajectory and the terminal device, the method comprising:
at the terminal device, performing a random wake-up and a blind acquisition of a carrier that is made available by a respective one of one or more airborne or spaceborne base stations to attach the terminal device to the non-terrestrial cellular data communication network; and
once the terminal device attaches successfully to the non-terrestrial cellular data communication network via one of the one or more base-stations, estimating terminal location data based on arrival times of at least three reference timing signals received at the terminal device from different positions taken by the one or more airborne or spaceborne base stations.
2. The method according to claim 1 , wherein performing the random wake-up and the blind acquisition of the carrier further comprises using offset estimates of a most recent downlink to pre-compensate its uplink transmission to attach itself to the network.
3. The method according to claim 1 , further comprising, upon successful blind acquisition of the carrier, at the terminal device, downloading synchronization assistance information from the one or more airborne or spaceborne base stations.
4. The method according to claim 1 , further comprising, upon successful blind acquisition of the carrier, at the terminal device, sending a location service request to the one or more airborne or spaceborne base stations.
5. The method according to claim 1 , wherein the estimating terminal location data comprises, at the terminal device, accumulating over time the respective arrival times of the at least three reference timing signals received at the terminal device from different positions taken by the one or more airborne or spaceborne base stations.
6. The method according to claim 5 , wherein the arrival times are accumulated from a single airborne or spaceborne base station changing its position relative to the terminal device over time.
7. The method according to claim 5 , wherein the non-terrestrial cellular data communication network comprises a plurality of airborne or spaceborne base stations each being configured to transmit a common synchronized reference timing signal, wherein the arrival times are accumulated from a set of the plurality of airborne or spaceborne base stations that are within the terminal device's line of sight at a same time, or from set of the plurality of plurality of airborne or spaceborne base stations changing their positions relative to the terminal device over time.
8. The method according to claim 5 , wherein the estimating terminal location data further comprises:
at the terminal device, computing, from said arrival times, at least two arrival time differences with respect to one reference arrival time;
at the terminal device, transmitting said computed differences to a location service node, through the one or more airborne or spaceborne base stations;
at the location service node, receiving the computed differences, computing a location estimate of the terminal device using the computed differences and information describing flight trajectory of the one or more airborne or spaceborne base stations, and transmitting the location estimate to the terminal device, through the one or more airborne or spaceborne base stations;
at the terminal device, receiving the location estimate from the one or more airborne or spaceborne base stations and storing it in a memory element of the terminal device.
9. The method according to claim 5 , wherein the estimating terminal location data further comprises:
at the terminal device, transmitting the arrival times to a location service node, through the one or more airborne or spaceborne base stations;
at the location service node, receiving the arrival times, computing, from the arrival times, at least two arrival time differences with respect to one reference arrival time, computing a location estimate of the terminal device using the computed differences and information describing flight trajectory of the one or more airborne or spaceborne base stations, and transmitting the location estimate to the terminal device, through the one or more airborne or spaceborne base stations;
at the terminal device, receiving the location estimate from the one or more airborne or spaceborne base stations and storing it in a memory element of the terminal device.
10. A non-transitory computer-readable storage medium having stored thereon instructions that, when executed on a terminal device having processing capabilities, causes the processor to execute a method for estimating a location of the terminal device, the instructions comprising:
performing, at the terminal device, a random wake-up and a blind acquisition of a carrier that is made available by a respective one of one or more airborne or spaceborne base stations to attach the terminal device to the non-terrestrial cellular data communication network; and
once the terminal device attaches successfully to the non-terrestrial cellular data communication network via one of the one or more base-stations, estimating terminal location data based on arrival times of at least three reference timing signals received at the terminal device from different positions taken by the one or more airborne or spaceborne base stations.
11. The non-transitory computer-readable storage medium according to claim 10 , wherein performing the random wake-up and the blind acquisition of the carrier further comprises using offset estimates of a most recent downlink to pre-compensate its uplink transmission to attach the terminal device to the network.
12. The non-transitory computer-readable storage medium according to claim 10 , wherein the instructions further comprises, upon successful blind acquisition of the carrier, downloading synchronization assistance information from the one or more airborne or spaceborne base stations.
13. The non-transitory computer-readable storage medium according to claim 10 , wherein the instructions further comprises, upon successful blind acquisition of the carrier, sending a location service request to the one or more airborne or spaceborne base stations.
14. The non-transitory computer-readable storage medium according to claim 10 , wherein the estimating terminal location data comprises instructing the terminal device to accumulate over time the respective arrival times of the at least three reference timing signals received at the terminal device from different positions taken by the one or more airborne or spaceborne base stations.
15. A terminal device for a non-terrestrial cellular data communication network, the terminal device comprising a processing unit configured to:
perform a random wake-up of the terminal device and a blind acquisition of a carrier that is made available by a respective one of one or more airborne or spaceborne base stations to attach the terminal device to the non-terrestrial cellular data communication network; and
once the terminal device attaches successfully to the non-terrestrial cellular data communication network via one of the one or more base-stations, estimate terminal location data based on arrival times of at least three reference timing signals received at the terminal device from different positions taken by the one or more airborne or spaceborne base stations.
16. The terminal device according to claim 15 , wherein performing the random wake-up and the blind acquisition of the carrier further comprises using offset estimates of a most recent downlink to pre-compensate its uplink transmission to attach the terminal device to the network.
17. The terminal device according to claim 15 , wherein processing unit is further configured to, upon successful blind acquisition of the carrier, download synchronization assistance information from the one or more airborne or spaceborne base stations.
18. The terminal device according to claim 15 , wherein processing unit is further configured to, upon successful blind acquisition of the carrier, send a location service request to the one or more airborne or spaceborne base stations.
19. The terminal device according to claim 15 , wherein processing unit is further configured to accumulate over time the respective arrival times of the at least three reference timing signals received at the terminal device from different positions taken by the one or more airborne or spaceborne base stations.