| OFDM(Orthogonal Frequency Division Multiplexing)is a high speed transmission technology. The sub-carriers of the system are orthogonal, so their frequency spectrum utilization is effective. Also because of the ability of anti-multipath and anti-frequency selective channel, it is the 4G key technology and the hot research topic.In this paper, we study the wireless communication baseband system base on OFDM, the frame structure of our OFDM system is similar to the one of IEEE802.11a. This paper Complete according to design part of the OFDM receiver baseband processor register transfer level (Register-Transfer Layer, RTL) of the complete design and FPGA implementation. We use the double window detection algorithm to synchronize the frame, long train sequence max interrelated value to frame synchronize, long train sequence delay interrelated to channel estimation, pilot channel to correct the phase offset, use 64-point FFT to demodule, use 16QAM to map the bits, and get the transmit bits. In the ISE8.2i Xilinx development environment, the design has frame detection module, bit synchronization module, operation module 64-point complex FFT, channel estimation module, and 16QAM demodulator module with the Verilog hardware description language. The design is stream line style and Process the signal in real time. Modelsim6.5a and Matlab7.0 simulation tools design simulation system for the unit module and system simulation; and for a series of system tests,design of the OFDM communication receiver system downloaded to the Spartan-â…¢FPGA hardware platform of Xilinx. Depending on the system software simulation and hardware test results are analyzed, which focuses on the analysis of the training sequences of OFDM synchronization performance.Simulation and test results show that:the design of the OFDM communication receiver system can correctly implement OFDM signal, such as frame synchronization and bit synchronization, correctly demodulate data. Each module and overall system simulation and download test results correctly. Since the FFT module precision is not enough, there are errors resulting in overall system simulation. |
