A new DS-CDMA code synchronization scheme

DS-CDMA is widely used in 3G communication systems, GPS, WLAN and some other fields that require robust resistance against narrow band interference, multi-path time spread or interception. One most challenging and important problem in DS-CDMA is code synchronization, which includes code acquisition and code track. When SNR of the received signal is low, the synchronization becomes not very reliable, which means the system will miss the correct phase of the received signal at a high probability. And therefore, more synchronization iteration is needed. If the PN code is very long, more iteration will become unaffordable because it elongates the synchronization time. In this paper, a non-coherent addition method is proposed to increase synchronization reliability. Another problem that hasnpsilat been discussed in previous literature is chip doppler. It will make the synchronization lose locked abnormally. In the paper, a PLL aid resample method is also proposed to solve this problem. LabVIEW simulation shows that above two methods are very effective.