Frequency offset in non-terrestrial networks

1. A method performed by a wireless device for operating in a non-terrestrial network, NTN, the NTN including at least one network node and a communication satellite, the at least one network node being one of a terrestrial base station, a satellite base station and satellite gateway, the method comprising:

obtaining a frequency offset corresponding to at least one of a Doppler shift of transmission and reception frequencies between the wireless device and the network node;

applying the frequency offset to an uplink transmission to the network node,

the uplink transmission being part of an initial access procedure; and

receiving an indication from the network node corresponding to a variation in Doppler shift over time, the indication including at least one of:

a further frequency adjustment indication;

a time for which the frequency adjustment indication is valid; and

configuring the wireless device with a plurality of frequency offsets and a corresponding duration for which each frequency offset of the plurality of frequency offsets is valid.

2. The method of claim 1 , further comprising receiving a frequency adjustment indication from the network node.

3. The method of claim 1 , wherein the applied frequency offset is transmitted to the network node.

4. The method of claim 1 , the method further comprising:

receiving a frequency adjustment indication in response the uplink transmission;

adapting the uplink transmission frequency based on the received frequency adjustment indication; and

transmitting a second uplink transmission according to the adapted uplink transmission frequency.

5. The method of claim 2 wherein the frequency adjustment indication comprises one of:

a relative increase or decrease of the used uplink frequency;

an absolute frequency offset relative to the nominal transmit frequency.

6. The method of claim 1 , further comprising:

receiving a broadcast indication of common portion of a Doppler shift, common to a plurality of wireless devices in a spotbeam footprint.

7. The method of claim 6 , wherein the frequency offset is obtained by receiving a frequency adjustment indication from the network node, wherein the frequency adjustment indication corresponds to a differential between the common portion and the Doppler shift at a location of the wireless device.

8. The method of claim 2 wherein the indication is received in a field of a downlink control information, DCI.

9. The method of claim 1 , further comprising:

receiving a parameter value corresponding to a Doppler frequency variation, wherein the obtained frequency offset corresponds to at least one variation in received Downlink (DL) transmission frequency and a previously obtained frequency offset when determined the at least one variation in the received DL transmission frequency exceeds the parameter value.

10. The method of claim 9 wherein the parameter value comprises a range of values.

11. A method performed by a network node, in a non-terrestrial network, the non-terrestrial network including a network node and a communications satellite, the network node being one of a terrestrial base station, a satellite base station and satellite gateway, the method comprising:

determining a Doppler shift estimate for transmissions between the network node and a wireless device;

transmitting a frequency adjustment indication to the wireless device, based on the determined Doppler shift estimate, the frequency adjustment indication being sent in one of:

a radio resource control message;

a medium access control message; and

a downlink control information message;

determining a variation in Doppler shift over time; and

sending an indication to the wireless device corresponding to the variation in Doppler shift, the indication of the variation in Doppler shift including at least one of:

a further frequency adjustment indication;

a time for which the frequency adjustment indication is valid; and

configuring the wireless device with a plurality of frequency adjustments/offsets and durations for which each offset is valid.

12. The method of claim 11 , wherein the frequency adjustment indication comprises one of:

a relative increase or decrease of the used uplink frequency; and

an absolute frequency offset relative to the nominal transmit frequency.

13. The method of claim 11 , wherein, the network node determines the Doppler shift estimate based on a random access message received from the wireless device and the frequency adjustment indication is transmitted to the wireless device in a random access response message.

14. The method of claim 11 , wherein the Doppler shift estimate comprises a portion common to a plurality of wireless devices in a spotbeam footprint the method further comprising broadcasting an indication corresponding to the common portion of the Doppler shift and wherein the transmitted frequency adjustment indication corresponds to a differential between the common portion and the Doppler shift at a location of the wireless device.

15. A wireless device comprising a power supply, memory, and processing circuitry, the processing circuitry configured to:

obtain a frequency offset corresponding to at least one of a Doppler shift of transmission and reception frequencies between the wireless device and a non-terrestrial network, NTN, network node, the network node being one of a terrestrial base station, a satellite base station and satellite gateway;

apply the frequency offset to an uplink transmission to the network node, the uplink transmission being part of an initial access procedure; and

receive an indication from the network node corresponding to a variation in Doppler shift over time, the indication including at least one of:

a further frequency adjustment indication;

a time for which the frequency adjustment indication is valid; and

configuring the wireless device with a plurality of frequency offsets and a corresponding duration for which each frequency offset of the plurality of frequency offsets is valid.

16. A network node comprising a power supply, memory and processing circuitry, the processing circuitry configured to:

determine a Doppler shift estimate for transmissions between the network node and a wireless device; and

cause the network node to transmit a frequency adjustment indication to the wireless device, based on the determined Doppler shift estimate, the frequency adjustment indication being sent in one of:

a radio resource control message;

a medium access control message; and

a downlink control information message;

determine a variation in Doppler shift over time; and

send an indication to the wireless device corresponding to the variation in Doppler shift, the indication of the variation in Doppler shift including at least one of:

a further frequency adjustment indication;

a time for which the frequency adjustment indication is valid; and

configuring the wireless device with a plurality of frequency adjustments/offsets and durations for which each offset is valid.

17. A non-transitory computer readable storage medium comprising instructions which when executed on a computer perform a method for a wireless device for operating in a non-terrestrial network, NTN, the NTN including at least one network node and a communication satellite, the at least one network node being one of a terrestrial base station, a satellite base station and satellite gateway, the method comprising:

obtaining a frequency offset corresponding to at least one of a Doppler shift of transmission and reception frequencies between the wireless device and the network node; and

applying the frequency offset to an uplink transmission to the network node,

the uplink transmission being part of an initial access procedure; and

receiving an indication from the network node corresponding to a variation in Doppler shift over time, the indication including at least one of:

a further frequency adjustment indication;

a time for which the frequency adjustment indication is valid; and

configuring the wireless device with a plurality of frequency offsets and a corresponding duration for which each frequency offset of the plurality of frequency offsets is valid.