SPREAD SPECTRUM MULTIPLE ACCESS SYSTEMS PERFORMANCE ANALYSIS

The problem of Spread Spectrum multiple access system, using a hybrid of direct sequence and frequency hopping has been studied. A randomized multiple access scenario is introduced. Statistical properties of interference signals due to the presence of other asynchronous users are thoroughly investigated. Upper Chernoff bounds on probability of error per bit for above multiple access systems in two different channels, namely AWGN(,2) and Rayleigh fading, are obtained. The notion of superiority and advantages of two different spread spectrum modulation techniques, i.e., direct sequence and frequency hopping, are addressed. An expression for prediction of the optimum number of diversities in slow non-selective Rayleigh fading channel has been formulated.

The problem of Code Division Multiple Access (CDMA) spread spectrum in slow non-selective Rayleigh fading channel with presence of thermal noise is readdressed. The interference signal due to presence of other synchronous users is shown to be Gaussian like processes. As a result, a closed form solution to probability of error per bit is obtained. An equivalent signal to noise ratio (SNR) is achieved, and it is shown in the absence of fading, above equivalent SNR reduces to that of Pursley, Aug. 1977.

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