Double Differential Modulation for LEO-Based Land Mobile Satellite Communication

In this article, we propose a double differential (DD) modulation technique for low earth orbit (LEO)-based land mobile satellite (LMS) communication to overcome the carrier frequency offset, which is an inevitable effect with the LEO satellites. The symbol error rate (SER) expressions for the considered scheme over Shadowed-Rician fading channels with phase-shift keying (PSK) constellations are presented. Since a closed-form expression cannot be derived for quadrature PSK and higher order PSK constellations, an upper bound and a lower bound of SER are derived. The error performance of the DD modulated LMS system is compared to that of coherent modulation-based and single differential modulation-based LMS systems, and a significant performance gain of the proposed DD modulation-based system is observed. Furthermore, we have also studied the effects of elevation angle and LEO trajectory on the error performance of the considered system.