OFDM系统中基于导符号和判决数据的频偏估计

The Frequency Offset Estimation Algorithm for OFDM Systems Based on Pilot Symbols and Decision Data

正交频分复用系统中为进行信道估计通常在OFDM符号中插入导符号,对利用这些导符号进行频偏估计的方法做了进一步研究.在时域和频域都重新推导了估计结果,经过合理近似,得到时域最大似然估计的近似解;在频域推导了另一种形式的似然函数,得出最大似然估计的解析表达式.新算法降低了计算量,提高了频偏估计精确度.同时,对利用导符号并结合判决数据进行频偏估计的算法也做了研究,判决数据的使用可以使估计结果更加精确.

In orthogonal frequency division multiplexing systems, the pilot symbols are often inserted for channel estimation. The frequency offset estimation algorithm using these pilot symbols was further analyzed. By modifying the derivation procedures both in time domain and frequency domain, and by the proper approximation, the approximate maximum likelihood estimation result in time domain was derived. Meanwhile, a different form of likelihood function in frequency domain was derived, and analytical estimation result was also given. The new algorithm decreases the computational complexity greatly, and increases the accuracy of the estimation greatly. The estimation algorithm using pilot symbols together with the decision data was also analyzed, and the accuracy of the estimation result can be improved by utilizing the decision data.