Performance Improvement of DCSK Modulation in Fading Channels Using Coherent Receiver with Channel Estimation

摘要

In this paper, we introduce a differential chaos shift keying (DCSK) with correlator receiver (DCSK-CR) scheme that uses a constant chaotic reference signal for all transmitted symbols. For this scheme, the orthonormal basis signals are completely known at the receiver and a coherent correlator-based structure is used to detect the symbols. Although the performance of a coherent receiver is better than that of a non-coherent receiver, the coherent case needs to know the channel state information to detect symbols in fading channels. Taking the chaotic reference signal constant in the proposed DCSK-CR system helps us to estimate the channel state information for detection. We drive the bit error rate (BER) performance of the proposed system in flat Rayleigh fading channels for both cases of errorless and maximum likelihood (ML) estimation of the channel coefficient. Thanks to the coherent structure, numerical results show that the BER performance of the proposed system outperforms the conventional DCSK case from 3 dB (for the ML case) to 8 dB (for the errorless case) in accordance with the channel estimation accuracy. It is shown that changing the chaotic map, initial condition and the chaotic parameter of the system, does not affect the BER performance of the proposed DCSK-CR, as DCSK. However, in contrast to the DCSK system, changing the spread factor in our system model has no effect on the BER.