| Orthogonal frequency division multiplexing (OFDM) is a multi-carrier modulation method. Due to variety of it'sadvantages such as high bandwidth efficiency and robustness against multi-path delay, it has been widely used in the fields of digital audio broadcasting, digital television and wireless local area networks and is likely to become one of key technologies of Fourth Generation mobile communications.However, one of the drawbacks of OFDM is the sensitivity to synchronization error, especially tofrequency offset. When a synchronization error exists, the orthogonality between sub-carriers can't be maintained, serious inter-carrier interference is introduced and demodulation performance will be degraded greatly. So perfect synchronization methods are essential to OFDM system.Firstly, this paper presents the principle of multi-carrier modulation technique-OFDM-applying to high bit rate transmission. The emphases are focused on the synchronization in OFDM technique. And this thesis studies, analyses and compares some synchronization methods. Many simulations are taken, the performances are given by simulation results, and some conclusions are given. Then Base on the cyclostationarity of OFDM symbol, a synchronization algorithm for the joint estimation of timing offset and frequency offset is proposed and discussed in detail and given the simulation results. Finally, the application of OFDM to IEEE802.11a Wireless Local Area Network is introduced.
|
PDF Full Text Request