Chaotic Synchronization Based Communications Using Constant Envelope Pulse

Abstract

We propose use of a constant envelope pulse for the purpose of improving noise-rejection property in chaotic synchronization based communication systems. In a conventional system where discrete-time chaotic signals are transmitted through the pulse amplitude modulation, the correlator output variance increases as the spreading factor decreases, while the synchronization error increases as the spreading factor increases. Therefore, it is difficult to control the bit error rate only by adjusting the spreading factor. In the proposed system, use of pulse width modulation keeps the envelope of transmitted signals constant, which leads to the correlator output with zero variance. The synchronization error is kept small because the spreading factor can be set to be one without increasing the correlator output variance. We have a result of computer simulation showing that the proposed system achieves a bit error performance better than the conventional system. In addition, a new blind adaptive algorithm is proposed which suppresses inter-symbol interference.