Channel equalization for multiuser chaotic communications systems

In a multiuser chaotic communications scheme, each user's information is modulated with a chaotic system and then transmitted independently over a common communication channel. The receiver sees the superposition of the distorted transmitted signals with additive noise. In this paper, a novel channel equalization algorithm is proposed for multiuser chaotic communications systems where each user's information is encoded using symbolic dynamics. The goal is to recover the chaotic signal being sent by each individual user so that its information can be estimated. This paper begins with the symbolic dynamics representation of chaotic systems being exploited to enable the representation of the multiuser chaotic system with an equivalent trellis diagram. Then, the trellis diagram is expanded to accommodate FIR channel distortions. Finally, the Viterbi algorithm is used to obtain maximum-likelihood estimates of the transmitted sequences. The performance of this algorithm in terms of bit-error rate (BER) is simulated for different channel distortions.