The Ka band for satellite communications is allocated from 27GHz to 40GHz and it is possible to realize the high speed data transmission in this 13GHz bandwidth. However, the attenuation especially the rain attenuation is tremendous for the Ka band. And we need to reserve about 4~8dB link budget to guarantee the typical link reliability 99.9% for the constant coding and modulation (CCM). In this paper, we propose a adaptive coding and modulation (ACM) algorithm that can dynamically change the modulation and code efficiency according to link condition. Based on this algorithm we only need reserve about 1dB to realize the 99.7% reliability. The simulation results show that we can derive more than triple throughout compare to CCM.

In this paper, a novel combined leakage CMA and direct decision (DD) adaptive algorithm using automatic iteration step adaptive blind equalizer is presented. In contrast to known CMA algorithm, the novel algorithm can approach the performance of mean-square error and fast convergent rate. For adaption of filters, efficient automatic iteration step and DD algorithm is present. The novel algorithm is lower computational complexity withO(N) and N is the filter order. Furthermore, the relation of novel algorithm to CMA algorithm is investigated. Finally, it is shown that proposed combined LCMA-DD algorithm is robust against amplitude and phase offset with fast convergence and mean-square error.