New Detection Methods of DS-CDMA Signal at Lower SNR

Abstract

D S-CDMA in the modern civil and military communications is widely used. Due to its low power spectral density, the DS-CDMA signal always floods in the background noise, bringing difficulties to the signal’s reconnaissance . Therefore, DS-CDMA signal detection has attracted attention of researchers. In this paper, the fourth-order moment chip (m4x(0,0,t) ) of DS-CDMA signal s is derived, against the background of Gaussian white noise, and get the conclusion that (m4x(0,0,t) can suppress Gaussian white noise. In order to reduce the estimation error of (m4x(0,0,t) , the quadratic fourth-order moment chip is proposed and finally t wo detection method s based on the quadratic fourth-order moment chip of DS-CDMA are proposed. Experimental results show that the detection performance of the method s is better than that of the double frequency method, spectrum-reprocessing method and cepstrum method. When the false alarm probability is 1%, the detection probability of presented methods reaches above 90% at SNR -2 2 d B .