Study On OFDM Based Wireless LAN

Orthogonal Frequency Division Multiplexing is one of key technologies in mobile communication fields. It is suitable for high rate data transmission in wireless channels because it can combat Inter-Symbol interference and multi-path fading efficiently. Now it has become an attractive technology. OFDM is a multiple carriers technology, supports high rate data transmission with high spectrum efficiency. At present, OFDM technology has been used in many fields, such as wireless local network, digital audio broadcasting (DAB), digital video broadcasting (DVB) systems and so on. It is very promising to be a core technology of the fourth generation mobile communications.In this thesis, we first discuss the basic theory of OFDM, and analyze why OFDM can effectively resolve the FSF and ISI, and how to realize the DFT-based OFDM system. And it is given for the new OFDM based wireless LAN standard IEEE 802. lla. Based on its packet structure, mathematical methods for OFDM symbol timing, carrier Frequency offset and channel estimation are proposed in this paper. In this thesis, we simulate OFDM system in MATLAB platform and analyze the relationship between FER, mapping, channel and OFDM system performance. At the last part we gives a new wavelet transform based OFDM and used to compare with the DFT-OFDM under the same conditions. The results are referential to the research of OFDM technology.