  In additive white gaussian noise (AWGN) channel, chaos has been proved to be
the optimal coherent communication waveform in the sense of using very simple
matched filter to maximize the signal-to-noise ratio (SNR). Recently, Lyapunov
exponent spectrum of the chaotic signals after being transmitted through a
wireless channel has been shown to be unaltered, paving the way for wireless
communication using chaos. In wireless communication systems, inter-symbol
interference (ISI) caused by multipath propagation is one of the main obstacles
to achieve high bit transmission rate and low bit error rate (BER). How to
resist multipath effect is a fundamental problem in a chaos-based wireless
communication system (CWCS). In this paper, implementation of a CWCS is
presented. It is built to transmit chaotic signals generated by a hybrid
dynamical system and then to filter the received signals by using the
corresponding matched filter to decrease the noise effect and to detect the
binary information. We find that the multipath effect can be effectively
resisted by regrouping the return map of the received signal and by setting the
corresponding threshold based on the available information. We show that the
optimal threshold is a function of the channel parameters and of the
transmitted information symbols. Practically, the channel parameters are
time-variant, and the future information symbols are unavailable. In this case,
a suboptimal threshold (SOT) is proposed, and the BER using the SOT is derived
analytically. Simulation results show that the CWCS achieves a remarkable
competitive performance even under inaccurate channel parameters.
