The Research On WCDMA Physical Layer Common Channels Demodulation Technology

Currently, 3G technology is very mature, and there are a lot of 3G users. As a member of the third generation mobile communication technology, WCDMA has been strongly promoted by the countries all over the world. WCDMA is a direct sequence spread CDMA technology, Which information is expanded into 3.84 Mchips, then transmitted in 5M bandwidth. It uses a variety of techniques to ensure QoS, support synchronous / asynchronous base station operating mode. At domestic and foreign, WCDMA physical layer common channels demodulation technique is implemented based on standardized 3GPP protocol,only specific algorithm slightly different.So, This paper summarizes the use of a common demodulation algorithm later,using offset algorithm and RAKE receiver technology to improve the performance of common channel demodulation techniques. In this paper, the WCDMA physical layer common channel demodulation techniques not only help to improve the performance of 3G networks demodulation technology, But also since 4G technology is the basis of the evolution of 3G technology comes on,So, promoting the evolution of 4G technology to a certain degree. This thesis is based on the WCDMA-based understanding of the theoretical knowledge, combined with practical algorithm to research physical layer common channels demodulation technology, and verified by MATLAB simulation. In the specific implementation process is divided into upstream and downstream channel demodulation. According to the provisions of the 3GPP,UE access to network contains cell synchronization, broadcast messages resolve to get cell information, Initiates a random access procedure and so on. The purpose of this paper is to improve the performance of demodulation technology and promote the evolution of 4G technology.First,this thesis analysis the required theoretical knowledge,and then design the method of demodulation.Then using MATLAB software to simulation the methods that designed for common channels demodulation.Finally,using offset correction and RAKE technology to improve the performance of demodulation.By comparison simulation using correction algorithm performance with and without correction algorithm Reconstruction and using RAKE receiver technology found that after using offset correction algorithm and RAKE receiver techniques the performance of demodulation physical layer common channels significantly improved. Therefore, this thesis will help improving the performance of existing demodulation techniques.