Realization Of The Fft In The Ofdm System With Channel Estimation Algorithm

The technology of orthogonal frequency division multiplexing (OFDM) has attracted a lot of focus for its excellent performance in the field of broadband wireless mobil communication systems. OFDM has been successfully applied in DAB, DVB-T and WLAN. Because of the demand for digitlized data, broadband personalized and mobile communication, OFDM has used in more and more applications in integrated wireless access communication field. It has been thought as the core physical layer technology of 4G mobile communications.This paper is a research about the algorithms of OFDM receiver, especially about the FFT process and channel estimation module. The signal model in this paper is the DVB-T standard.This paper is organized as follows:Chapter one, as a introduction, gives the brief concept of digital communication, the character of wireless channel and the development of OFDM.Chapter two describes the fundamental theory of OFDM. According to the syetem model, a basic theoretical analysis about principles and implementations of the main parts of OFDM syetem is given. The scheme of DVB-T is also presented in detail since our system is associated with DVB-T standard.Chapter three provides the related aigirithms of FFT processor design in OFDM receiver. First, the basic algorithms and structures are analyzed. Then, an effective implementation scheme of the FFT processor is presented, in which the algorithm about generation of twiddle factor and structure of butterfly computation is improved. The result shows that it reduces the needed memory of twiddle factor and increases the efficiency of the butterfly computation.Chapter four is mainly about the algotithm of channel estimation. After the analysis and comparison of the basic channel estimation interpolation algorithm, a novel 2-D interpolation aigorithm of channel estimation with low complexity is presented. The simulation results show that it has a better performance compared with traditional interpolation methods. Besides, an equalization and ICI cancellation module is used after channel estimation to improve the syetem's performance.In Chapter five the work of this thesis is summarized and some notions for the future research are given.