Second Order Time-Frequency Modulation in Satellite High-Mobility Communications

Providing reliable wireless communications for high-mobility terminals remains one of the main challenges faced by satellite high-mobility communication systems. Because the high Doppler frequency offset and Doppler rate caused by the high-mobility nature of the mobile terminal, and low signal-tonoise ratio (SNR) circumstances caused by limited satellites’ link budgets degrade the system performance seriously. To solve such a problem in high-mobility satellite communications, we propose a novel modulation method named second order time-frequency (SOTF) modulation, which consists of index modulation (IM) and liner frequency modulation (LFM). Simulation results show that the bit error ratio (BER) performance of the proposed modulation method with different parameters is better than traditional modulation methods. Specially, the BER performance loss is about 0. 05dB in high-mobility communication scenarios, which demonstrates that the proposed modulation method is insensitive to Doppler frequency offset and Doppler rate. Overall, the proposed method can be well applied in high-mobility satellite communication systems for its good performance with moderate complexity.