Authors : Karim Kemih , Malek Benslama and Henri Baudrand
Abstract: There has been recent interest in satellite-based personal communications systems using Code Division Multiple Access (CDMA) and direct sequence spread spectrum (DS/SS) modulation. For Low Earth Orbit Satellite (LEOS) systems. There are notable differences between LEOS and terrestrial CDMA implementations and these affect the design of the signal structure used for multiple access. Two constraints imposed by LEOS systems are the potential for large relative delays and large Doppler shifts. This study considers these constraints in the design of a synchronization strategy. The proposed approach use chaotic Chen system to establisher synchronization between transmitter and receiver in the presence of constant attenuation and offset. An analytic algorithm that provides closed form channel and carrier offset estimates is presented. The principle of this approach is based on adding a compensation block before the receiver to compensate the distortion of the imperfect channel by using genetic algorithm. The resultants presented, show that the receiver is able to recover rapidly the synchronization with the transmitter.
Karim Kemih , Malek Benslama and Henri Baudrand , 2006. Synchronized Chaotic Chen System in CDMA Satellite Communication Using Genetic Algorithm. Asian Journal of Information Technology, 5: 1301-1305.