Symbol Synchronization Technique Research And Performance Simulation In MC-CDMA Systems

MC-CDMA technology based on CDMA and OFDM technologies makes a flurry of research and development activities in mobile communication systems. MC-CDMA has the advantages of these two techniques. However, it also has some disadvantages of the two techniques. The technology is not sensitive to time delay of channel, and can rake the frequency. Perhaps it can resolve the question of high speed data flow transmitted in wireless channel, either its frequency spectrum availability is high. But MC-CDMA systems is sensitive to frequency offset and the start position offset of symbol that are caused by Doppler frequency expanding and mismatching between transmitter’s and receiver’s device. To assure the performance of MC-CDMA systems is the key point of this paper.In this paper firstly we review the history of the wireless communication, and then introduce the concept of the multi-carrier modulation and wireless channel. After introduced the multi-carrier modulation, we learn the fundamental principles of OFDM&CDMA. On the basis of these introductions, three methods of combination of CDMA and OFDM are introduced, especially the method of MC-CDMA. The comparison of the three methods is also obtained later. Then in the paper introduced the synchronization technique in MC-CDMA. The synchronization technique of MC-CDMA system includes symbol synchronization and carrier synchronization, etc. The premise of other synchronizations is acquisition and tracking of PN sequence and it’s also the basis of effective process of received information data. We deeply analysis the symbol synchronization technology based on the correlation property of PN code and cyclic safeguard interval of ML is discussed in detail and simulated in computer. On the basis of algorithm of the basic correlation property of PN code, we propose an ameliorative algorithm in this paper. After using the correlation property of PN code to accomplish the approximate acquisition, we use different PN code as cyclic prefix of MC-CDMA frame accomplishes exact trace. Although this algorithm brings down utilization in frequency spectrum availability, but it can arise a lower complexity, higher accuracy and shorter consumption of time at the aspect of tracing frame.