Ofdm Synchronization And Fractional Fourier Transform In Ofdm

As the requirement of the communication qualities is getting even higher, the information technologies are developed forwardly. In this condition, new communication technologies are introduced continuously. The old technologies are optimized, perfected and even replaced by the new ones. The development of the communication technologies has endured several generations as below: the 1^st generation (whose kernel technology is FDMA technology), the 2^nd generation (whose kernel technology is TDMA and CDMA technologies), the 2.5^th generation (whose kernel technology is GPRS and CDMA1X technologies), the 3^rd generation (whose kernel technology is WDMA in Europe, CDMA2000 in the USA and the TD-SCDMA in China). At present we are between the 2^nd and the 3^rd generations in using communication technologies. But in the researching fields, we have stepped into the 4^th generation, which the scholars all over the world admitted. The technology of the 4^th generation of the communication technology is OFDM.Based on the principle of the OFDM technology, the multi-carriers modulation has strong abilities in counteracting the multi-path response. However, there are still some difficulties in realizing the technologies. The synchronization of the OFDM technology is one of the difficulties. In the paper, the synchronization of the OFDM technology is in-depth discussed. It can be divided into 5 parts.In Chapter 1, the development of the OFDM technology and its foreground in application are introduced. In this chapter the puzzles that the OFDM technology is used in the 4^th communication generation is brought forward. The main part of the paper is about the synchronization of the OFDM technology, and a new system arithmetic to the problem is put forward, which is named as the Fractional Fourier Transform.In Chapter 2, the principle of the OFDM signal transforming technology is introduced. Then the production of the OFDM signal in the mathematics is described. The problems discussed the ISI and the ICI occurred when the OFDM signal transmitted in the wireless channel. The method that is used commonly in eliminating the ISI and the ICI is introduced briefly. The transmission system and the receiving system of the OFDM signal are stimulated at last.In Chapter 3, the classical synchronize arithmetic is expressed and stimulated. The characteristic curve can be educed in the stimulation. Based on the classical arithmetic, a new OFDM System arithmetic is brought forward, which is named as The Arithmetic of the OFDM System Based on the Fractional Fourier Transform.In Chapter 4, the continuous and the discrete realizations of the Fractional Fourier Transform OFDM system are explained separately. Then the received signal of the OFDM signal and the Fractional Fourier Transform signal passed dispersed-multi-path are deduced in the mathematics separately.In Chapter 5, the main work of the paper is concluded. Then some insufficiencies in this paper are introduced, lastly the directions of the research are also expressed.