Design and realization of an FPGA-based generator for chaotic frequency hopping sequences

Chaos-based pseudonoise (PN) sequences for spread spectrum (SS) communications ranks amongst the most promising applications of chaos to communications. This paper deals with the design and realization of a chaotic frequency hopping (FH) sequence generator that is compatible with current FH/SS technologies. A simplistic generator architecture adopting nonlinear auto-regressive (AR) filter structures is proposed, which is based on the random sequence model and the metric entropy criterion for generation of random sequences. Conventional PN sequences are employed to perturb the generator such that the resulted sequences fulfil the FH requirements on period and family size. In addition, a chaos-based FH sequence generator prototype is realized in field programmable gate arrays (FPGAs) and various tests are performed. The generator produces long period FH sequences with uniform distribution over the available bandwidth, large linear complexity as well as suboptimal Hamming correlation properties. Bit error rate (BER) performance of the chaos-based asynchronous FH/CDMA system is evaluated by means of computer simulation. These results suggest that the cost-effective and well-performing generator has the potential to be incorporated into existing FH systems.

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