The Design And Implementation Of OFDM System Receiver Based On FPGA

As the key technology of current mainstream wireless communication system,Orthogonal Frequency Division Multiplexing has the advantage of high spectrum efficiency and reduce channel interference,and it also can be combined with lots of new technologies,such as Space-Time Coding, Multiple-Input Multiple-Output,Smart antenna and Software Radio. So the OFDM technology has highly practical value.This thesis first analyzes the development of mobile communication, application status of OFDM technology and the problems existing in the design of OFDM system,and put forward the scheme to slove the problems. Then illustrates the IEEE802.11 a which used in this thesis as wireless local area network standard. Based on the analysis of the mathematical model and the basic principles of OFDM system, we lead to the key technology and detail the architecture of OFDM system. Besides,this thesis improved the timing synchronization algorithm for enhance the stability and anti-interference ability of OFDM system.The design includes hardware design and software design. According to the OFDM system parameter, we chose the FPGA chip and the ADC chip. In the hardware electric circuit design, we completed the design of FPGA chip XC3S500E-4PQ208 and the chip’s peripheral circuit design, such as analog-to-digital conversion, UART communication and USB communication.The software design programmed modules for the OFDM systems by Verilog HDL language in the development environment of ISE, those modules include frame finding module, carrier restoration module, timing synchronization module, Fast Fourier Transformation module, channel estimate and equalization module, sampling frequency synchronization module, phase tracking module, demodulation module,deinterleaves module, Viterbi decoding module and descrambler. Finally, all the modules’ function and sequence in time were simulated by the software Modelsim.The simulation results are consistent with the expectations, and the software design ofthe OFDM receiver is completed.