Research On Synchronization Of MC-CDMA System

In recent years, Wireless communication is developing very fast. Data transmission rate in the existing communication networks can no longer meet customers'requirements. Therefore, people pay close attention to the fourth generation mobile communication system. Multicarrier Code Division Multiple Access (MC-CDMA) technique, based on Code Division Multiple Access (CDMA) and Orthogonal Frequency Division Multiplexing(OFDM), has the following advantages ,such as insensitive to the channel time delay, high spectrum efficiency and low complexity .It can solve the high-speed information transmission problem in wireless channel. So MC-CDMA has wide application prospects in mobile communication, satellite communication, wireless access and ultra-wideband communication. It is honored as an effective solution way in 4G mobile communication.This paper first reviews on the history and present situation of MC-CDMA, also analyses its basic principle and system performance. As the system is very sensitive to the frequency offset and timing error which are the results of Doppler shift or the local oscillator not match between the transmitter and the receiver. To ensure the performance of MC-CDMA system, synchronization problem is important and is a research hotspot. This paper first analyses the possible interference in MC-CDMA and the impact of the interference on the system performance in detail, also focuses on the timing synchronization methods and carrier interference self-cancellation technique, gives out the corresponding synchronization algorithm and performance simulation. The last part of the paper is to research the MC-CDMA system uplink quasi-synchronous problem. The algorithm to solve the problem is making a new signal format which has head/tail guard intervals in one symbol duration.This paper combines MC-CDMA own characteristics, shows a variety of synchronization methods applicable to the system, and each method is analyzed by simulation. The result is helpful for the further study of MC-CDMA synchronization problem.