Low complexity transmit processing for multibeam satellite systems with non-linear channels

Aggressive frequency reuse is being considered for multibeam satellites to achieve higher system capacity using available spectrum. Towards achieving the ideal gains of such a reuse, precoding techniques are being considered to minimize the resulting co-channel interference. Most of the precoding techniques, however, do not explicitly consider the distortions introduced by the high power amplifier (HPA), an integral part of the satellite payload, which is inherently non linear. A power efficient amplification introduces non-linear co-channel distortions at the receiver, including the effects of high peak to average power ratios (PAPR), typical of spectrally efficient modulations. This work provides a novel processing at the Gateway comprising a cascade of linear and non-linear operations (Crest Factor Reduction, and Signal Predistortion) to counter the non-linearities and co-channel interference in multibeam satellite systems. The proposed architecture has a lower number of parameters than existing works, leading to efficient coefficient estimation as well as reduced implementation complexity. These parameters are optimized using the simulated annealing algorithm to enhance the Signal to Interference plus Noise ratio at the receiver and the performance is compared with the state-of-the-art.