A New Receiver Design for Protograph-Coded Reference Reused DCSK Systems

In this letter, we investigate the performance of protograph-coded reference reused differential chaos shift keying (DCSK) systems to improve the transmission reliability. The traditional protograph-coded DCSK receiver does not take full advantage of the reused chaotic reference signals and hence cannot obtain desirable error performance. To solve this problem, we design a new receiver architecture called
weighted reference estimation and iterative decoding (WRE-ID)
, which can universally improve the performance of protograph-coded reference reused DCSK systems over both multipath Rayleigh fading and additive white Gaussian noise channels. In particular, we put forward the WRE algorithm to estimate reference signal in order to calculate log-likelihood ratio (LLR) more precisely. Furthermore, extrinsic information output from the decoder is utilized to iteratively recalculate the weight of the WRE algorithm. As a further illustration, we derive the LLR expressions of the proposed WRE-ID-aided receiver of a typical protograph-coded reference reused DCSK (i.e., high-efficiency DCSK) system. Analytical and simulated results show that the proposed WRE-ID-aided receiver can always overtake the traditional receivers in reference reused DCSK systems. Hence, the protograph-based reference reused DCSK systems with the proposed receiver are very promising for high-rate high-reliability wireless applications.