NR-DCSK Based Chaotic Communications in MIMO Multipath Channels

Abstract

In this paper, digital chaotic communications in multiple-input–multiple-output (MIMO) wireless multipath fading channels is considered. A noise reduction-differential chaos shift keying (NR-DCSK) scheme is employed to modulate data symbols at each transmit antenna which transmits signals omni-directionally. In the transmitter side, we use β/P chaotic samples as reference sequences which is then repeated P times to generate the required reference sequence of length β. At the receiver side, a moving average filter of size P is used to reduce the noise variance of the received signal so as to enhance the system performance. The resulting filtered signal is then correlated and combined using diversity combining techniques to yield the transmitted symbol. It is shown that with spatial diversity gains, the enhancement in bit error rates (BER) of the proposed system is much better than the conventional M-DCSK based MIMO Chaotic Communication systems. Moreover, a closed-form expression for BER of the proposed system is derived over AWGN and Rayleigh fading channel conditions. Comparison of simulation results with theoretical BER expressions of additive white Gaussian noise (AWGN) and Rayleigh fading channels for various system parameters like signal to noise ratio, Spatial diversity orders, combining techniques have been carried out to test the performance enhancement of the proposed NR-DCSK based MIMO system.