Research On Adaptive Transmission Technique For Ka-band Satellite Communications

The traditional C and Ku bands communication systems cannot satisfy theincreasing communication needs of the personal life and socio-economic activities. TheKa band satellite communication has therefore been an emerging technology in recentyears. However, the channel conditions can affect the Ka-band satellite communicationsgreatly. Thus, how to mitigate the impact of rainfall and ionospheric convection hasbecome the main issue of the Ka-band communication. In this thesis, to deal with theissue, LDPC codes based adaptive coding and modulation (ACM) and power controlare proposed for the Ka-band satellite communications. The main works are as follows:1. Two Ka-band satellite channel models are established. And then the errorperformance of Scale-Free Quasi-Cyclic Low-density Parity-Check code(SF-QC-LDPC) designed for Ka-band satellite communications has been evaluatedunder the AWGN channels.2. An adaptive coding and modulation method based on SF-QC-LDPC codes hasbeen proposed, in which the switching threshold is determined by the Lagrangethreshold optimization method so as to maximize the throughout under the average BERconstraints. Simulation results show that the proposed method can effectively improvethe throughput performance of the system under study.3. A power control method for Ka-band satellite communications has beendeveloped, which can reduce the transmission power with guarantying the systemperformance in terms of throughout. Simulation results demonstrate that theeffectiveness of the developed method.