Reliable Transceiver Design of LEO Satellite Communication Systems with Doppler Effect and Multipath and Amplification Nonlinear Distortions

With the advancement of wireless communication technology, satellite communications have the advantages of wide coverage and low latency. Low-earth-orbit (LEO) satellite communication systems have an important role in 6G technology development in the future. However, high-frequency and high-relative speed lead to Doppler effect, which will seriously affect the performance of the demodulator at the receiver. Meanwhile, for the high transmission power of the antenna, signal distortion caused by the non-linear effect of power amplifier (PA) needs to be considered. In this paper, we use Gaussian Minimum Shift Keying (GMSK) modulation technique as the main transceiver. It is found that under the non-ideal transmission, e.g., Doppler frequency offset and multipath channels effects, the continuous phase modulation (CPM) characteristics can effectively reduce multipath channel interference and nonlinear distortion. Also, the demodulation scheme using cross-coupled detector method can reduce the frequency offset effect. Moreover, the proposed modem scheme combined with the Quasi Cyclic LDPC (QC-LDPC) channel coding and the hybrid LDPC soft decoding method proposed herein, the error rate performance has better than using the min-sum algorithm decoding method alone.