# US 11,309,957 B2 · Method and system for non-terrestrial cellular wireless communication networks

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- Number: US 11,309,957 B2
- Document ID: US11309957B2
- Status: Granted
- Kind: B2
- Application number: 17/227,218
- Filed: 2021-04-09
- Published: 2021-09-23
- Granted: 2022-04-19
- Earliest claimed: 2018-10-12
- Assignees: OQ Technology S.á.r.l.
- Applicants: OQ Technology S.á.r.l.
- Inventors: Omar Qais Talib Qaise; Prasanna Balasubramanian Nagarajan; Cyril Marc Dufoing
- Web page: https://patentgrep.com/patent/US11309957B2

## CPC

- H04B 7/18539: {Arrangements for managing radio, resources, i.e. for establishing or releasing a connection}
- G01S 19/00: Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- H04B 7/18504: {Aircraft used as relay or high altitude atmospheric platform}
- H04B 7/18547: {for geolocalisation of a station (position fixing by direction or distance determination G01S5/00)}
- H04W 84/06: Airborne or Satellite Networks (space-based or airborne stations H04B7/185)
- Y02D 30/70: in wireless communication networks
- H04B: TRANSMISSION
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

The invention provides a method and an architecture for deploying non-terrestrial cellular network base stations, so as to enable cellular network coverage in remote areas, where no fixed infrastructure is available. The proposed methods allow for efficient power management at the terminal devices that need to synchronize to the airborne or spaceborne cellular base stations. This is particularly important for IoT devices, which have inherently limited power are computing resources.

## Claims

### Claim 1

A control method for a terminal device in a non-terrestrial cellular data communication network, the network comprising an 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 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, computing, based on said flight trajectory data and said terminal location data, estimate values for said base station, comprising any of a future position, elevation, velocity, or any combination thereof;
storing these estimate values in the memory element;
using the data processing unit, determining a time slot during which a wireless communication channel between said terminal device and said base station is estimated to be available, based on said estimate values; and
using the data processing unit, scheduling a data reception or transmission between said terminal device and said base station during the determined time slot,
wherein the terminal device receives, during said scheduled time slot, a synchronization signal from said base station, the synchronization signal carrying data indicating a transmission frequency and timing information, which are required for the terminal device to synchronize future data transmission or data reception to/from said base station,
wherein the terminal device computes, using the data processing unit, an observed Doppler shift based on the receiving frequency for said synchronization signal and on the transmission frequency indicated therein, and wherein the terminal device pre-emptively compensates said transmission frequency by a frequency compensation value during a subsequent data transmission to said base station, said frequency compensation value taking into account said observed Doppler shift.

### Claim 2 (depends on 1)

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

### Claim 3 (depends on 1)

The method according to claim 1, wherein said step of providing flight trajectory data comprises, at the base station, 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 base station through a wireless data communication channel.

### Claim 4 (depends on 1)

The method according to claim 1, wherein said flight trajectory data comprises an identifier of said base station, ephemeris data, altitude data, velocity data or any combination thereof.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the step of providing terminal location data comprises the additional step of estimating the terminal device's location based on detected properties of at least three signals received at the terminal device from different positions taken by at least one base station.

### Claim 6

A control method for a terminal device in a non-terrestrial cellular data communication network, the network comprising an 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 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, computing, based on said flight trajectory data and said terminal location data, estimate values for said base station, 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;
storing these estimate values in the memory element;
using the data processing unit, determining a time slot during which a wireless communication channel between said terminal device and said base station is estimated to be available, based on said estimate values; and
using the data processing unit, scheduling a data reception or transmission between said terminal device and said base station during the determined time slot,
wherein the terminal device receives, during said scheduled time slot, a synchronization signal from said base station, the synchronization signal carrying data indicating a transmission frequency and timing information, which are required for the terminal device to synchronize future data transmission or data reception to/from said base station, wherein the terminal device computes, using the data processing unit, an observed time shift based on a reception time of said synchronization signal and on the timing information indicated therein, and wherein the terminal device pre-emptively compensates the scheduled time of transmission by a time compensation value during a subsequent data transmission to said base station, said time compensation value taking into account said observed time shift or any derivative thereof.

### Claim 7 (depends on 6)

The method according to claim 6, wherein said time compensation value further takes into account a constant timing offset that is a function of the base station's position.

### Claim 8

A terminal device for a non-terrestrial cellular data communication network, the terminal device comprising:
a data transmission unit,
a data reception unit,
a first memory element for storing flight trajectory data of an airborne or spaceborne base station of said network,
a second memory element for storing terminal location data, and
a processing unit,
wherein the terminal device is configured to, during said scheduled time slot, receive a synchronization signal from said base station, the synchronization signal carrying data indicating a transmission frequency and timing information, which are required for the terminal device to synchronize future data transmission or data reception to/from said base station,
wherein the processing unit is configured to:
compute, based on said flight trajectory data and said terminal location data, estimate values for said base station, comprising any of a future position, elevation, velocity, or any combination thereof,
store these estimate values in a third memory element,
determine a time slot during which a wireless communication channel between said terminal device and said base station is estimated to be available, based on said estimate values,
schedule a data reception or transmission between said terminal device and said base station during the determined time slot,
compute an observed Doppler shift based on the receiving frequency for said synchronization signal and on the transmission frequency indicated therein, and
pre-emptively compensate said transmission frequency by a frequency compensation value during a subsequent data transmission to said base station, said frequency compensation value taking into account said observed Doppler shift.

### Claim 9 (depends on 8)

The terminal device according to claim 8, being a user equipment or a ground-based gateway node serving a plurality of user equipments.

### Claim 10 (depends on 8)

A non-terrestrial cellular data communication system comprising at least one terminal device according to claim 8, and at least one airborne or spaceborne base station.

### Claim 11 (depends on 8)

The terminal device according to claim 8, wherein the processing unit is configured to schedule the data reception or transmission by switching the terminal device's state from a first state, in which the terminal device is not capable of receiving or transmitting data, to a second state, in which the terminal device is capable of receiving data using the data reception unit or transmitting data using the data transmission unit.

### Claim 12 (depends on 8)

The terminal device according to claim 8, wherein the data reception unit is configured to receive said flight trajectory data from said base station through the wireless data communication channel.

### Claim 13 (depends on 8)

The terminal device according to claim 8, wherein said flight trajectory data comprises an identifier of said base station, ephemeris data, altitude data, velocity data or any combination thereof.

### Claim 14 (depends on 8)

The terminal device according to claim 8, wherein the processing unit is configured to estimate the terminal location data based on detected properties of at least three signals received at the terminal device from different positions taken by said base station.

### Claim 15

A non-transitory computer readable recording medium program comprising code portions which when run on a computer, causes the computer to:
compute, based on flight trajectory data of an airborne or spaceborne base station and terminal location data of a terminal device, estimate values for said base station, comprising any of a future position, elevation, velocity, or any combination thereof;
store these estimate values in a memory element;
determine at least one time slot during which a wireless communication channel between said terminal device and said airborne or spaceborne base station is estimated to be available, based on said estimate values; and
schedule a data reception or transmission between said terminal device and said airborne or spaceborne base station during the determined time slot,
wherein the terminal device receives, during said scheduled time slot, a synchronization signal from said base station, the synchronization signal carrying data indicating a transmission frequency and timing information, which are required for the terminal device to synchronize future data transmission or data reception to/from said base station, wherein the terminal device computes, using the data processing unit, an observed time shift based on a reception time of said synchronization signal and on the timing information indicated therein, and wherein the terminal device pre-emptively compensates the scheduled time of transmission by a time compensation value during a subsequent data transmission to said base station, said time compensation value taking into account said observed time shift or any derivative thereof.

### Claim 16

A terminal device for a non-terrestrial cellular data communication network, the terminal device comprising:
a data transmission unit,
a data reception unit,
a first memory element for storing flight trajectory data of an airborne or spaceborne base station of said network,
a second memory element for storing terminal location data, and
a processing unit, wherein the processing unit is configured to:
compute, based on said flight trajectory data and said terminal location data, estimate values for said base station, comprising any of a future position, elevation, velocity, or any combination thereof,
store these estimate values in a third memory element,
determine a time slot during which a wireless communication channel between said terminal device and said base station is estimated to be available, based on said estimate values, and
schedule a data reception or transmission between said terminal device and said base station during the determined time slot,
wherein the terminal device is configured to, during said scheduled time slot, receive a synchronization signal from said base station, the synchronization signal carrying data indicating a transmission frequency and timing information, which are required for the terminal device to synchronize future data transmission or data reception to/from said base station,
wherein the processing unit is configured to:
compute an observed time shift based on the reception time of said synchronization signal and on the timing information indicated therein, and
pre-emptively compensate the scheduled time of transmission by a time compensation value during a subsequent data transmission to said base station, said time compensation value taking into account said observed time shift or any derivative thereof.

### Claim 17 (depends on 16)

The terminal device according to claim 16, wherein said time compensation value further takes into account a constant timing offset that is a function of the base station's position.