Hyperchaos-Based Spreading Codes Generator for DS-CDMA Communication Systems

In this paper, we propose a new hyperchaos-based spreading codes generator (HSCG) for multi-users direct sequence spread spectrum (DSSS) communication systems. For experimental validation, we implement the proposed generator in Xilinx FPGA Virtex-5 technology. Contrary to the traditional spreading codes, the proposed HSCG offers interesting statistical properties such as good autocorrelation, very small cross-correlation, no repetition of the generated spreading codes and high degree of security. In addition, the developed hardware architecture used for implementing the HSCG permits to generate simultaneously an infinite number of multi-length spreading codes with high hardware performances in terms of logic area consumption, throughput and latency. Real-time results are given for 32-, 64- and 128-bit chaotic spreading codes. All of these properties are validated and compared with that of classical codes (Gold sequences, Walsh-Hadamard) through bit error rate (BER) performance evaluation in a DS-CDMA system in AWGN and time-invariant multipath channels. With its interesting performances, the proposed HSCG is very useful for the next generations of mobile communication systems.