Doppler correction for a high-speed mobile station in a satellite mobile telephone system
OwnerMark Grayson, Tania Le Goff +1inventors
InventorsMark Grayson, Tania Le Goff, Sze-Ching Lu
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Abstract
Doppler-shift correction information broadcast in a satellite mobile telephone system is produced on the assumption that mobile stations (4a, 4b) are stationary or moving slowly. Consequently, a mobile station (4a, 4b) moving at high-speed cannot correct properly for Doppler shift. In order to solve this problem, provision is made for the mobile station (4a, 4b) to know its own position and velocity, as well as that of a satellite (3a, 3b), so that it can tune its transmitter to mimic, from the perspective of the satellite (3a, 3b), a stationary or slowly moving mobile station (4a, 4b).
Claims18
A method of operating a mobile station in a satellite mobile telephone system, the method comprising the steps of:
- obtaining mobile station data defining the position and velocity of the mobile station;
- calculating the Doppler shift for transmissions between the mobile station and a satellite from the mobile station data and satellite data defining the position and velocity of the satellite;
- and
- transmitting to a satellite using a frequency determined by said calculated Doppler shift so as to pre-compensate for Doppler shift affecting the transmission.
A method according to any preceding claim, wherein the mobile station data is obtained from a navigation apparatus.
A method according to any preceding claim, wherein the satellite data comprises position and velocity data for a satellite.
A method according to any preceding claim, including propelling the mobile station at a speed not less than 100 km/h while said transmission to a satellite is being performed.
A mobile station for a satellite mobile telephone system, the mobile station including a controller programmed to cause the mobile station to operate according to a method according to any preceding claim.
Dependencies are inferred from the claim text.