Ofdm Demodulation, Synchronization And Carrier Deviation Is Estimated That The Simulation Realization

One of the requirements of next generation of wireless mobile communication system is to provide the transmission of the multi-media services with higher speed and wider bandwidth. In the wireless environment, the frequency resources, power and wireless fading channel etc. restrict higher data transmission. In these years, OFDM (Orthogonal Frequency Division Multiplexing) technique has attracted more and more attention, because it has strong transmission ability in wireless channels, which comes from its own parallel transmission mechanism, inherited robustness to inter symbol interference (ISI) and the diversity with the multi-path channel. Meanwhile, OFDM system has very high channel utilization ratio because of the orthogonal properties among its sub-carriers. Consider realization, the modulation and demodulation of OFDM can be realized by IFFT and FFT technique. With the development of DSP and FPGA, the realization of FFT becomes much easier, and the cost of OFDM becomes lower. Now, the OFDM technique has been widely applied in digital audio broadcasting (DAB) system, digital video broadcasting (DVB) system, IEEE802.11a and Hyperlan/2 system etc.In this paper, firstly the history of OFDM technique is introduced. So are the advantage and the disadvantage of OFDM. According to the basic OFDM theory, the OFDM signals peculiarity and the model of common OFDM system is given, followed by explaining the basic characteristic of wireless channel and typical channel model.Secondly, the effects of carrier frequency offset, sampling clock offset, and symbol timing offset on OFDM signals are exploited. For the symbol timing synchronization problem, methods using the head training sequences of OFDM frame is introduced; Point to the sample clock offset, a method using the pilot equally interpolated in the OFDM symbol is investigated and improved into new methods which use linear regression and Kalman filter. Contrasting to the capability between the old and new methods is done under AWGN channel by simulation. The carrier frequency offset problem is solved by two different methods, one is to use the pilot equally interpolated...