Performance Analysis Methods for Non-Coherent Differential Chaos-Shift-Keying Systems

Abstract

Coherent systems such as the chaos-shift-keying (CSK) system studied in the previous chapter are theoretically better than their non-coherent counterparts in terms of performance in additive white Gaussian noise (AWGN) channels. However, as practical techniques for robust chaos synchronization are not yet available for the required signal-to-noise conditions, the requirement of the receivers to reproduce replicas of chaotic carriers remains a major technical barrier to the practical implementation of coherent systems. Without the need for chaos synchronization, non-coherent systems therefore represent more practical forms of systems, despite their less favorable performance. In this chapter we focus on non-coherent chaos-based communication systems. In general, non-coherent detection can take a variety of forms, but its basic principle is to make use of some distinguishable properties of the transmitted signals, which can be some generic deterministic properties (e.g., return-map based detection [Tse et al. (2001)] and maximum-likelihood method [Kisel et al. (2001)]), or fabricated by a suitable bit arrangement (e.g., differential CSK (DCSK) [Kolumbán et al. (1996)]). In particular, we investigate in depth in this chapter, using the discrete-time baseband model described in Sect. 2.6, the DCSK system under single-user and multi-user environments. Broadly we may classify the implementation of multiple access into two types, namely, time-delay-based [Kolumbán et al. (1997c); Kennedy et al. (1998)] and permutation-based [Lau et al. (2002a)] implementations. In this chapter we present the analysis and performance evaluation of these two types of multiple access as applied to DCSK systems.