A TECHNIQUE FOR ORTHOGONAL FREQUENCY-DIVISION MULTIPLEXING FREQUENCY OFFSET CORRECTION
A TECHNIQUE FOR ORTHOGONAL FREQUENCY-DIVISION MULTIPLEXING FREQUENCY OFFSET CORRECTION
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DOI：
10.1109/26.328961
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发表时间：
1994-10-01
影响因子：
8.3
通讯作者：
MOOSE, PH
中科院分区：
文献类型：
--
作者：
MOOSE, PH
本文讨论了频率偏移对正交频分复用（OFDM）数字通信性能的影响。频率偏移的主要问题是它在OFDM信号的多个载波之间引入干扰。结果表明，并通过仿真证实，为了保持 OFDM 载波的信号干扰比为 20 dB 或更大，偏移量被限制为载波间间隔的 4% 或更小。接下来，本文描述了一种使用重复数据符号来估计频率偏移的技术。推导出最大似然估计（MLE）算法，计算其性能并与仿真结果进行比较。由于载波间干扰能量和信号能量都对估计有相干贡献，因此即使偏移太大而无法解调数据值，该算法也会生成极其准确的估计。此外，估计误差仅取决于总符号能量，因此它对信道扩展和频率选择性衰落不敏感。描述了一种策略，用于在初始偏移的不确定性超过载波间隔（MLE 算法的限制）的 1/2 的情况下进行初始捕获。
This paper discusses the effects of frequency offset on the performance of orthogonal frequency division multiplexing (OFDM) digital communications. The main problem with frequency offset is that it introduces interference among the multiplicity of carriers in the OFDM signal. It is shown, and confirmed by simulation, that to maintain signal-to-interference ratios of 20 dB or greater for the OFDM carriers, offset is limited to 4% or less of the intercarrier spacing. Next, the paper describes a technique to estimate frequency offset using a repeated data symbol. A maximum likelihood estimation (MLE) algorithm is derived and its performance computed and compared with simulation results. Since the intercarrier interference energy and signal energy both contribute coherently to the estimate, the algorithm generates extremely accurate estimates even when the offset is far too great to demodulate the data values. Also, the estimation error depends only on total symbol energy so it is insensitive to channel spreading and frequency selective fading. A strategy is described for initial acquisition in the event of uncertainty in the initial offset that exceeds 1/2 the carrier spacing, the limit of the MLE algorithm.