Research On Performance Of Complex Scrambling Code

The mobile telecommunication systems have undergone three generations:the first generation is analog telecommunication system (1G) and the second generation is digital communication system (2G), and the3G system focuses on multimedia traffic and wireless internet.2G and3G are used widely at present and the4G system will provide stronger function and higher bit rate to people in the near future.There are mainly three3G standards:CDMA2000, WCDMA and TD-SCDMA (TD). Comparing with GSM and IS-95that are2G standards, the technique of Complex Scrambling Code (CSC) has been introduced, which would affect the performance of the systems in some fields. First, the technologies of CSC used in CDMA2000, WCDMA and TD are discussed in this paper by mathematical analysis combined with Matlab simulation, and also the detailed constellations of those systems with CSC are presented. After the comparing between the two different methods of CSC used in CDMA2000and TD systems respectively, the equivalent method between the two spreading spectrum and scrambling code schemes used in those two standards are presented in the paper. Basing on the spreading spectrum and scrambling code scheme used by TD, an experimental scheme of spreading spectrum and scrambling code for TD (MSS-TD) is proposed, which would assimilate the merits of those two spreading spectrum and scrambling code schemes in TD and CDMA2000. Finally, based on the research above, the analysis of the impacts for different spreading spectrum and scrambling code schemes used in three systems to Signal-to-Noise Ratio (SNR), Bit Error Rate (BER) and Peak-to-Average Ratio (PAR) are carried out by mathematical analysis and Matlab simulation.