Research On Synchronization Techniques Of Sw Ofdm Systems

With the increment of information requirement,high speed communication systems have developed quickly. Meanwhile signal's bandwidth has enlarged gradually along with the wireless communication systems. Thus the equalization has to be more and more complicated to diminish the inter symbol interference (ISI). In this situation, multicarrier modulation (MCM) begins to reveal its excellence against ISI. Orthogonal Frequency Division Multiplexing (OFDM), as one mode of MCM, has been paid much more attention since its'orthogonal'does endow many advantages, such as high frequency band availability,easy to realize modulation by FFT and in possession of ant fading ability. Therefore, OFDM has been a support technique in the B3G/4G wideband wireless communication systems. However, this'orthogonal', on the other hand, makes OFDM fragile due to the carrier frequency offset. It is this shortcoming that makes synchronization more important in OFDM systems. According to B3G downlink's demand, this paper gives a study of OFDM synchronization algorithm.In this paper, two synchronization algorithms, Training Sequence Based (TSB) algorithm and Guard Interval Based (GIB) algorithm, are discussed and analyzed. Stemmed from the former one, an improved frequency acquisition algorithm has been proposed by the author. This new algorithm not only tracks the fractional frequency offset (FFO), but also estimates the integral frequency offset (IFO), which surely enlarges the frequency acquisition range.At last, the paper gives a synchronization scheme of SW OFDM systems and shows its performance through simulation. Besides, the paper simplified the algorithm for convenience of project. The algorithm can get precise synchronization in the multipath channel with low SNR, which meets requirements of practical working systems.