An oversampling-correlation receiver for enhancing performance of chaotic DS-CDMA systems over flat fading channels

This paper investigates a correlator-type receiver based on oversampling technique, which can exploit flat-fading characteristic to enhance the performance of chaotic direct-sequence/ code division multiple access (Chaotic DS/CDMA) systems over multipath fading channels. At the input of the receiver, the incoming signal is oversampled before putting into the correlator. This oversampling process aims at determining different multipath components from the flat fading channel, which can be combined together in order to increase signal-to-noise ratio (SNR) at the output of the correlator. Mathematical models in discrete-time domain for multiple-access operation in the transmitting side, flat Rayleigh fading channel with multiple delay-path as well as the proposed receiver are presented. BER performance of the receiver is determined by means of numerical simulations in terms of bit-error-rate (BER) against the typical parameters of the system, such as number of delay paths, transmission delays and fading coefficients, ratio of E_b=N₀, spreading factor, and oversampling frequency. Obtained results point out a beneficial feature of the proposed receiver that is the increment of delay-path number also leading to the enhancement of BER performance.