Implementation of Digital Chaotic Signal Generator Based on Reconfigurable LFSRs for Multiple Access Communications

This paper presents the implementation of digital chaotic signal generator “twisted map” based on reconfigurable LFSRs. The robust digital implementation eliminates the variation tolerance and electronic noise problems common in analog chaotic circuit. In this paper an improved piece-wise linear one-dimensional iterative map such as “twisted map” with reconfigurable LFSRs is used to generate the chaotic signal for all users. The initial conditions of the sequence generators can be randomly selected to produce reconfigurable chaotic sequence with good correlation properties. The main advantages of this paper are to increase security of the transmission and to ease the generation of a great number of distinct sequences. In practice, the following simulation results on MATLAB software platform and DSP builder show that the effectiveness of the model described which has very low cross-correlation (approximately 0.002 for this architecture). For the proposal system, the bandwidth is extended from approximately 50 Hz to 50 MHz. The period length and the crosscorrelation properties of the resulted sequence are compared to m-sequence, gold-sequence and other chaotic sequences generators such as tent map.