Doppler Compensation in Non-Terrestrial Networks

An apparatus in a communication system comprising at least one processor;

• and at least one non-transitory memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform:
• obtain a set of Doppler shift curves for different distances to one or more satellite orbits;
• perform measurements of satellite transmission to obtain estimate of instantaneous Doppler shift of the transmission, the measurements comprising a timestamp;
• calculate a Doppler shift curve corresponding to the measurements;
• determine a time offset on the curve utilising the timestamps of the measurements, the time offset indicating the position of the Doppler shift of the apparatus on the curve;
• determine the Doppler shift of the satellite transmission utilising the curve and the time offset, wherein determining the time offset comprises comparing the measured instantaneous Doppler shift values to the values on the curve and determining the time offset based on the timestamps of the measurements;
• and
• apply the determined Doppler shift in receiver operations.

A method in an apparatus in a communication system comprising:

• obtaining a set of Doppler shift curves for different distances to one or more satellite orbits;
• performing measurements of satellite transmission to obtain estimate of instantaneous Doppler shift of the transmission, the measurements comprising a timestamp;
• calculating a Doppler shift curve corresponding to the measurements;
• determining a time offset on the curve utilising the timestamps of the measurements, the time offset indicating the position of the Doppler shift of the apparatus on the curve;
• determining the Doppler shift of the satellite transmission utilising the curve and the time offset, wherein determining the time offset comprises comparing the measured instantaneous Doppler shift values to the values on the curve and determining the time offset based on the timestamps of the measurements;
• and
• applying the determined Doppler shift in receiver operations.

A non-transitory computer readable medium encoded with a computer program comprising instructions for causing an apparatus to at least perform:

• obtaining a set of Doppler shift curves for different distances to one or more satellite orbits;
• performing measurements of satellite transmission to obtain estimate of instantaneous Doppler shift of the transmission, the measurements comprising a timestamp;
• calculating a Doppler shift curve corresponding to the measurements;
• determining a time offset on the curve utilising the timestamps of the measurements, the time offset indicating the position of the Doppler shift of the apparatus on the curve;
• determining the Doppler shift of the satellite transmission utilising the curve and the time offset, wherein determining the time offset comprises comparing the measured instantaneous Doppler shift values to the values on the curve and determining the time offset based on the timestamps of the measurements;
• and
• applying the determined Doppler shift in receiver operations.