Estimation of link carrier-to-noise ratio in satellite communication systems

In a satellite network, the transmit power levels of satellite terminals have to be carefully controlled to minimize interference to neighboring satellites and maintain the allocated satellite power level to the terminal. Satellite links encounter various propagation impairments, such as rain fading effects, that require adaptively changing the transmit power level, coding/modulation and spread spectrum rates to compensate for these impairments. The link carrier-to-noise (C/N) estimation process plays a key role in facilitating such adaptive techniques. The C/N estimation process for a typical satellite communication system is presented and analyzed in this paper. It is shown that estimating the C/N is particularly challenging when the received signal C/N ratio is large. In this paper, novel approaches to estimating the C/N ratio are proposed to overcome these challenges.