Study On Synchronization Of OFDM Demodulation System

Orthogonal frequency division multiplexing (OFDM) has been widely applied in Broad-band Wireless Access systems due to its high data transmit rate, good performance in anti multi-path fading and high bandwidth efficiency as well as other prominent advantages. But the orthogonal multicarrier modulation, which is the main character of OFDM, determines that it is very sensitive to both timing synchronization error and carrier frequency offset, and it is necessary to eliminate effectively about all kinds of asynchronization influence. Besides OFDM is employed as the Physical layer access technology of IEEE 802.11a WLAN system, which is widely recognized as a typical outburst grouping transmit system. So it is important for OFDM system to accurate synchronization, and now synchronization in OFDM has become a hotspot in the research of modern communication.The history of OFDM technology development and the characters of multi-channel and the Physical criterion of IEEE802.11a has been briefed in this dissertation. And the basic principle of OFDM system, application trait and technique preponderance are also expatiated. Then by the way of theoretical discursion to discuss the effect of timing offset, carrier offset, sampling offset those who three factors on OFDM system. And the methods of simulation are also used to make a detailed analyze and comparison of the different algorithms estimation performance,by the way of programme based of IEEE802.11a protocol principle and AWGN(Additive White Gaussian Noise)channel。By the way of different algorithm simulation performance compare, go deep into a new timing algorithm ,then proved it's better estimate capability and practicality to the Self delay correlation algorithm and the time domain cross-correlation algorithm, especially in the worse Signal-to-Noise condition.Finally,to design a OFDM based of IEEE802.11a standard, according to the performance requirements of the synchronization system. Meanwhile, to design different parts of this system correspond to different algorithms. Then by the way of Quartus and ModelSim simulation to verify the validity of the OFDM synchronization system and the reliability of wireless transmission.