基于FPGA的OFDM小数频偏估计实现方法

Implementation Method of OFDM Fractional Frequency Offset Estimation Based on FPGA

频偏估计是通信接收系统中的关键组成部分,它关系到OFDM接收系统的整体性能.从两个经典理论算法出发,提出一套基于FPGA的OFDM通信系统小数频偏估计的实现方案.主要描述了小数频偏估计相关算法的基本理论;如何对OFDM序列添加频偏值以及对频偏后的数据进行小数频偏估计并对数据进行补偿输出.该方案各部分模块程序皆由Verilog-HDL语言进行描述,同时在Xilinx公司EDK软件ISE环境下进行综合,然后应用Modelsim SE 6.5b软件进行仿真.实验结果表明,系统各部分模块工作良好,能够对频偏值做出准确的估计,并满足设计要求.

Estimation of fractional frequency offset is a key part of Orthogonal Frequency Division Multiplexing （ OFDM ） system. It is related to the overall performance of an OFDM receiver system. The two classic theories were researched in this paper, and an implementation method of OFDM communication system fractional frequency offset estimation based on FPGA proposed. Meanwhile, this paper mainly describes the basic theory of the algorithm; how to generate the fractional frequency offset phase sequence ; and how to estimate the fractional frequency offset and compensate the frequency offset data. All the modules of fractional frequency offset estimation circuit are described in Verilog-HDL and constructed by IP cores supplied by Xilinx. And do all simulations by using Xilinx 13.3 ISE analysis tool, Modelsim SE 6.5b tool. Finally, experiment results show that the received signals which completed fractional frequency offset compensation are consistent with the original signals. And the results indicate correctness and validity of the scheme designed.