Performance enhancement of open-loop power control for satellite communication systems

A method of controlling an uplink transmission power in a satellite communication system having at least one satellite for transmitting and receiving communications signals over a downlink and uplink respectively, the downlink communications signal being attenuated by a downlink attenuation level while traveling over the downlink, the downlink attenuation level having a downlink attenuation component caused by satellite antenna pointing error and a downlink attenuation component caused by rain, the uplink communications signal being attenuated by an uplink attenuation level while traveling over the uplink, the uplink attenuation level having an uplink attenuation component caused by satellite antenna pointing error and an uplink attenuation component caused by rain, the method comprising:

• determining an amount of a downlink attenuation component caused by satellite antenna pointing error;
• determining an amount of a downlink attenuation component caused by rain by measuring a downlink attenuation amount and subtracting the amount of said downlink attenuation component caused by satellite antenna pointing error from said downlink attenuation amount;
• and
• adjusting an uplink transmission power based on the amount of the downlink attenuation component caused by satellite pointing error and based on the amount of the downlink attenuation component caused by rain.

An uplink transmission power control system comprising:

• a ground station for measuring an amount of downlink attenuation of a communications signal passing over the downlink from a satellite;
• a processing station for determining satellite antenna pointing direction with respect to the ground station;
• and
• a communication link for carrying the satellite antenna pointing direction to the ground station;
• wherein
• the ground station determines an amount of an antenna pointing error attenuation component of said downlink attenuation based on said satellite antenna pointing direction and an amount of an atmospheric attenuation component of said downlink attenuation and determines an uplink transmission power adjustment based on said amount of the antenna pointing error attenuation component and said amount of the atmospheric attenuation component to compensate for said downlink attenuation.