Comparing Research On The Csc Between TD-SCDMA And CDMA2000 System

Analog cellular systems are commonly referred to as the first generation systems (1G). The digital systems currently in use, such as GSM (Global System for Mobile Communications), PDC (Personal Digital Cellular) and IS-95, are the second generation systems (2G). As 2G have already met people's requirements of voice mobile communications, the third generation systems (3G) should be designed for wireless internet and multimedia traffic mainly. There are four 3G main standards: WCDMA, CDMA2000 1x, TD-SCDMA, as well as WiMAX, the first three of which are based on CDMA mode.Compared to IS-95 and GSM, both TD-SCDMA and CDMA2000 1x introduced the technique of Complex Scrambling Code (CSC). In the TD-SCDMA standard, the principle and realization of complex spectrum spreading, weighting factor for Walsh code, and dedicated complex scrambling code are even adopted. Therefore,it is necessary to research on the system performance after different CSC technique having been employed. Through the comparison investigation of spreading spectrum and scrambling code between CDMA2000 and TD-SCDMA, an equivalent scheme of spreading spectrum and scrambling code for TD-SCDMA is presented firstly. The equivalent scheme indicates that the basic principles of the spreading spectrum and scrambling code of the two standards are identical in nature. Based on the above analysis, through the mathematical deduction and Matlab simulation, we analyse the constellation of CSC circuit in detail, research on the impact on Bit Error Ratio (BER), Signal-to-Noise Ratio (SNR), Peak-to-Average Ratio (PAR) from CSC technique, and research on the impact on the system performance from Orthogonal Diversity Transmission (ODT) and Quasi-Orthogonal Address Code Interference (QOACI) introduced by CSC technique. Finally, we present an experimental scheme of spreading spectrum and scrambling code for TD-SCDMA (MSS-TD) as well as the comparison analysis of system performance. The proposed scheme integrates the merits of the both standards as CDMA2000 and WCDMA, therefore the system performance, such as SNR, BER, etc, would be improved.