2003•Journal of Tsinghua University(Science and Technology)Requires access
Application of chaotic sequences in QS-CDMA systems
Sun Shouyu
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Abstract
A method is presented to optimize the chaotic sequences for spreading codes of quasi synchronous code division multiple access (QS CDMA) systems. In a QS CDMA system, the relative delay between the signals of different users is random but restricted to a specified time range, so correlation functions around the origin influence system performance and odd function are as important as the even functions. Chaotic sequences generated from a logistic map with different initial values were checked using the quasi orthogonal criteria to select the qualified sequences. Monte Carlo simulations of the QS CDMA system with optimized chaotic sequences as spreading codes on additive white Gaussian noise (AWGN) channel show that these sequences are quasi orthogonal and suitable for application in the QS CDMA system.