Production et adaptation du changement de la fréquence doppler dans les systèmes de communication par satellites de type LeO

Abstract

Doppler shift is a natural phenomenon in mobile communication and causes severe phase distortion and performance degradation especially in LEO mobile communication systems. This distortion comes from the faster movement of a satellite relative to that of a terminal and an earth station. Because the satellite has a bigger relative velocity to the surface of the earth, the Doppler frequency shift affects the carrier frequency largely in received signal from of communication canal. Doppler has to be estimated and compensated for to enable reliable communication. In this work, we propose a new Doppler prediction scheme using location information of a user terminal and a satellite. In this prediction method for the Doppler frequency using change Ali's algorithm, the user terminal can be know its position on the earth and the distance between satellite and use terminal. The showed simulation results can be adapt can for ameliorate the prediction frequency shift. The comparison between Ali's method and our method is a most applicable in LEO and MEO satellite systems and have a lot of information on the user terminal and satellite. We makes the LEO satellite systems with of a range an altitude between 1,000 km and 2,000 km and inclination the 53° for circular orbit.