Chip rate estimation of weak DSSS signals based on improved delay-multiply in non-cooperative communication systems

To solve the parameter estimation of direct sequence spread spectrum (DSSS) signals with low signal to noise rates (SNR) in non-cooperative communication systems, this paper presents a wavelet decomposition-based delay-multiply method with accumulation to estimate the chip rate of weak DSSS signals. In this proposed method, the wavelet decomposition will be employed to filter out the high frequency component and some noise without any prior knowledge due to the difference in characteristics between DSSS signals and noise. The impact on the estimation performance of the chip rate, which results from noise, can be further decreased by accumulation of power spectrum of DSSS signals. Theory analysis and computer simulation results show that the improved delay-multiply method with accumulation can accurately estimate the chip rate of the weak DSSS signal in non-cooperative communication systems when the pre-filter can´t be designed without any prior knowledge and the SNR is very low.