Research And Implementation On OFDM Carrier Synchronization Algorithm Based On 802.11a

With the development of communication technology, the requirement of communication is to provide higher speed and higher quality of information transmission. On the premise of high speed of data transmission, the impact of channel for single carrier system becomes more complex; the processing methods become more and more complex. The emergence of OFDM technology is a very good method to solve this problem, through multi-channel parallel carrier transmission, effectively reducing the transmission rate for each way, which reduces the impact of the wireless channel. OFDM can improve the utilization rate of bandwidth, and can reduce the impact of multipath time delay, and the characteristics of high speed information transmission, OFDM became one of the important technologies of 4G and 5G.And carrier frequency synchronization technology as one of the essential technology, the realization of carrier synchronization has important significance for the whole OFDM system.First of all, in this thesis, the basic principle and key technologies of OFDM system is introduced, and it analyses the impact of carrier frequency offset for the OFDM system, and it introduces the core thought and basic principle of OFDM carrier frequency synchronization algorithm which is based on auxiliary data and maximum likelihood algorithm used cyclic prefix.Secondly, in this thesis, it introduces the physical layer of IEEE802.11 a. Because the characteristics of IEEE802.11 a system frame’s structure and the complexity of hardware implementation for carrier synchronization algorithm, so carrier synchronization algorithm using maximum likelihood estimation algorithm which through multiple frequency offset value for the average to improve the estimation precision of the algorithm. Under the OFDM system based on IEEE802.11 a, through the MATLAB simulation to analyze the algorithm, we find it can meet the system requirements.Finally, this thesis introduces the carrier synchronization algorithm based on FPGA hardware implementation in detail, and through the ISE to complete the functional simulation and FPGA circuit testing. In the process of the OFDM system joint debugging, carrier synchronization module can work normally and recover the carrier frequency offset.