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This paper is devoted to the derivation of an exact analytical expression of the bit error rate for chaos-based DS-CDMA systems. For the studied transmission system, we suppose that synchronization is achieved perfectly, coherent reception is considered, and an Additive White Gaussian Noise channel (AWGN) is assumed. In the first part of the paper, performance of a mono-user system with different chaotic sequences is evaluated and compared in terms of the error probability. This comparison is realized thanks to the probability density function of the bit energy of a chaotic sequence. The bit error rate can be easily derived by numerical integration. In some particular cases, for certain chaotic sequences with known probability density function of bit energy, we propose an analytical expression of the bit error. In the second part of the paper, the performance of a chaos-based DS-CDMA system is evaluated in the multi-user case. A general conclusion is that probability density function of chaos bit energy, for a given spreading factor, can give a clear idea about how to choose a "good" chaotic sequence for improving the performance of the chaos-based CDMA system.Keywords Chaos-based DS-CDMA · Energy distribution · Bit error rate · Multi-user interference

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In this paper, we present a generalized accurate methodology to predict the bit error rate performance for non-coherent chaos-based communication systems. The Gaussian approximation approach, which is widely used to compute the performance of such systems, leads to inaccurate results, especially with respect to low spreading factors. Our new approach based on the chaos bit energy distribution gives accurate results even for low spreading factors. The system is studied and simulated under an additive white Gaussian noise, Rice and Rayleigh channels. Finally, we compare our approach to the Gaussian approximation approach. Computer simulations shows a high accuracy for our method, especially for small spreading factors.

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