Adaptive power and rate control for satellite communications in Ka band

Adaptive power and rate control for efficient use of satellite channels in the Ka band are considered. Fading due to rain is modeled as a log-normally distributed, auto-regressive process with known statistics. Adaptation policies based on MMSE channel estimation are designed taking into account the effect of channel estimation errors in an optimal manner so as to satisfy the required outage probability for given fading dynamics. Analytical results show average power savings or average bit rate increase that are available from adaptive techniques. It is demonstrated that a large improvement over a non-adaptive system is available provided an appropriately designed adaptation scheme that makes use of the channel fading statistics. Finally, practical methods based on adaptive modulation level selection in a fixed-bandwidth system are evaluated analytically in terms of average bandwidth efficiency.