Design And Implementation Of Frame Detection And Synchronization Algorithm For OFDM System Based On FPGA

Orthogonal frequency-division multiplexing (OFDM) is a multi- carrier digital modulation technique. It has the characteristics of high spectrum efficiency and great ability of eliminating multi-path interference, and aroused particular concern in broadband wireless multimedia communication field.OFDM systems can work in either continuous mode or burst mode. The latter one is adopted in some wireless LAN standards, such as IEEE802.11a and HiperLAN Type2. In this mode, the receiver detects the frame which has a certain fixed format at first. This paper introduces a frame detection algorithm based on the minimum error probability principle, and gives its realization in FPGA.As one of the most crucial technique of OFDM, synchronization technique includes carrier frequency synchronization and symbol synchronization. Carrier frequency synchronization rectifies the carrier frequency offset between transmitter and receiver, ensuring the orthogonality among sub-carriers, and symbol synchronization determinates the beginning of useful data in an OFDM symbol, which is also the starting moment of FFT window. In this paper, a carrier frequency synchronization algorithm based on autocorrelation has been introduced and realized in FPGA firstly, especially the Cordic algorithm and its realization. Secondly, two symbol synchronization algorithm based on crosscorrelation and autocorrelation are introduced and implemented in FPGA, then the comparison between them is made in the view of realization. Besides, the methods of area diplex and pipelining are embodied in implementation scheme of FPGA.The system debugging is introduced at the end of this paper, and a debugging method that combines ChipScope Pro with Matlab is presented here. The method can also be used in the debugging process for FPGAs realization of other algorithm.