Ofdm Communication System’s Timing Synchronization And Frequency Offset Estimation Research And FPGA Implementation

Today’s society is in an era of information explosion. There is an urgent requirement that people want to obtain faster and larger amount of information, which presents a challenge to traditional communication technologies.Traditional communication systems are mostly single-carrier communication system. Single-carrier communication system is simple and easy to implement, so it dominated the communications sector for a very long time until the the emergence of multi-carrier communication systems. Single-carrier communication system uses high-speed serial data stream to transmit information. Because symbol duration is so short, it is easy to cause inter-symbol interference. Multi-carrier communication system can avoid this drawback, which uses low-speed parallel data stream to transmit information. Besides, it reduces the data rate, which makes the symbol duration longer, effective against the inter-symbol interference. OFDM communication system is a common multi-carrier OFDM communication system, and it adds cyclic prefix before each symbol, which against the inter-symbol interference more effective.Although the OFDM system can against the inter-symbol interference in case of improving the transmission rate, it also has a very significant disadvantages, that is more sensitive to frequency offset, which is determined by characteristics of subcarriers. In the current volatile wireless transmission environment, a variety of fading can affect the OFDM system, especially small-scale fading, which causes timing error and frequency offset. Timing synchronization and frequency estimation technology is a key technology of the OFDM system.At present, the timing synchronization and frequency estimation techniques can be divided into three categories:The first category is a timing synchronization and frequency estimation algorithm based on cyclic prefix, the second category is a timing synchronization and frequency estimation algorithm based on the training sequence, and the third category is non-data-aided blind estimation algorithm.This thesis recognizes the importance of timing synchronization and frequency estimation technology for OFDM systems by analyzing the difference between single-carrier communication system and multi-carrier communication system, wireless channel fading model, the timing errors and frequency offset. In the last two chapters of the thesis, I completed the simulation of existing timing synchronization and frequency offset estimation algorithm, OFDM system implementation and achieved good results.