Optimal spreading in multi-user non-coherent binary chaos-shift-keying communication systems

Optimal spreading for multi-user non-coherent binary chaos-shift-keying (CSK) communication systems with correlation demodulating is considered in this paper. The bit error rate (BER) of the system is calculated by a dynamical-improved Gaussian approximate (DIGA) approach. The lower bound of the BER performance is deduced and the optimal spreading factor is calculated from this BER bound; it is validated by simulation experiments. The main contribution of the paper is to show that the optimal spreading factor in the non-coherent differential CSK (DCSK) is approximately linear with the signal-to-noise ratio (SNR) and the square root of the number of users.