文档介绍：摘要
摘要
正交频分复用(OFDM)技术具有抗多径时延扩展、频谱利用率高、硬件实现简
单等优点,近年来得到了广泛关注,并有望成为第四代移动通信系统的核心技术。
但 OFDM 技术对定时和频率偏移敏感,如何克服这个缺点是 OFDM 技术研究的主
要方向之一。
本文重点研究了有关定时和频偏估计的两类算法:数据辅助即基于导频符号
估计算法和非数据辅助即盲估计算法。文中给出了基于导频符号估计算法中的经
典算法 Sch-Cox 算法。这类算法捕获快、精度高,但由于插入导频符号带来了资
源浪费,降低了系统数据传输效率。而盲估计算法不需要导频符号,避免了插入
导频符号带来的资源浪费,节省了带宽,因而更具有吸引力。因此本文对盲估计
算法进行了深入的研究,给出了利用循环前缀的联合估计算法和利用虚子载波的
频偏估计算法,详细给出了它们的系统模型和算法描述并对它们进行了仿真实验
和性能分析。最后本文对文中给出的算法进行了性能比较和总结。
关键词:正交频分复用(OFDM) 定时估计频率偏移估计基于导频符号估计
盲估计
ABSTRACT
ABSTRACT
Orthogonal frequency division multiplexing (OFDM), with the advantages of
robustness against multipath delay spread, high bandwidth efficiency, and simple
hardware implementation, etc., has gained increased interest in the recent years, and is
likely to e the key technology for the fourth generation munications
system. However, OFDM is sensitive to timing and frequency offset, so how to
e this limitation is one of the main directions of the research on OFDM.
The algorithms for estimating timing and fequency offset are studied in the thesis.
They are divided into two categories: data-aided estimator, namely estimator based on
the pilot symbols, and non-data-aided estimator, namely blind estimator. The Sch-Cox
algorithm based on the pilot symbols is given in the thesis. Estimator based on the pilot
symbols has quick acquisition and high precision, but the insertion of the pilot symbols
wastes the system resource and reduces the system data transmission efficiency. While
blind estimator doesn’t need the pilot symbols, avoids the waste of the system resource,
and saves the bandwidth. So blind estimator is studied deeply in the thesis. A joint
estimator using the cyclic prefix and a frequency offset estimator using the virtual
carriers are given. Their system models and particular algorithm descriptions are given,
and their simulations and performance analyses are done. In the end the performance of
the algorithms pared and a summary is given.