2013 Volume 4 Issue 4 Pages 473-481
We evaluate the performance of the chaotic code division multiple access (CDMA) on realistic communication environment. The previous researches on asynchronous chaotic CDMA systems have shown that the bit error rate (BER) can be reduced by using the chaotic sequences. It has been mathematically clarified that the cross-correlation among the chaotic sequences can be minimized by using those with negative autocorrelation in the asynchronous CDMA. For such chaotic CDMA with negative autocorrelation, it has been also clarified by numerical simulation that the sequences with the Gaussian shaped chip makes better BER performance than the general Nyquist shaped chip. In this paper, we implement the chaotic CDMA using a few software-defined radio (SDR) devices for more realistic investigation. Experimental results obtained by our implemented system on the SDR clarify that the spreading sequence with a specific negative autocorrelation and the Gaussian shaped chip sequence makes the BER lower in asynchronous CDMA system.
