| The Orthogonal Frequency Division Multiplexing (OFDM) technology is a high-speed multi-carrier transmission scheme, and is one of the key technologies in IEEE 802.16e physical layer protocol. Extensive attention has been paid to OFDM due to its advantages such as high spectral utilization rate, high data transfer rate and the ability to oppose the multipath interference. OFDM system is made up of many orthogonal sub-carriers, synchronization errors would cause severe Inter Channel Interference, Inter Symbol Interference, and demodulation performance will be degraded greatly. Therefore, OFDM system is extremely sensitive to symbol timing error and carrier frequency offset, synchronization has become one of major research topics in this domain.In this paper, the evolution history of OFDM system is reviewed, and the fundamental principles in OFDM are briefly introduced. After analyzing the effects of synchronization errors on the system performance, training symbol based on joint symbol timing and carrier frequency synchronization algorithm is introduced and discussed in detail. The system simulations and performance analysis are made to each classic algorithm. A novel synchronization algorithm which can get impulse response timing curve for OFDM system applied to IEEE 802.16e standard is designed. Based on the analysis of Complementary Code properties and the performance boundary of training symbols, a new pilot with different structure and a new timing metric formula are proposed. The proposed algorithm makes full use of the ideal auto-correlation property of the Complementary Code, not only can get rid of the timing plateau in Schmidl algorithm, but also eliminate the side-peak in Park timing algorithm.The proposed synchronization scheme is evaluated in MATLAB. The simulation results validated that performance of the proposed method much better than conventional methods both in symbol timing and in carrier frequency offset estimation. |
PDF Full Text Request