基于前导字的WLANOFDM系统载波频偏估计

Carrier Frequency Estimation for WLAN OFDM System Based on Preamble

载波同步是正交频分复用(OFDM)系统的一项关键技术。利用帧前导字中的重复性训练序列进行频偏估计是一种简便有效的处理方法。本文根据Morelli和Mengali[3]算法,提出适用于无线局域网系统IEEE802.11a OFDM[1]的载波频偏估计算法和性能界。在此基础上,提出将短和长训练序列的估计结果综合考虑的两种估计算法,进一步改善估计性能。

Carrier frequency of IEEE802.11a WLAN OFDM system is investigated. Carrier frequency synchronization is one of the key techniques of OFDM system. Among all frequency estimation techniques, the methods based on preamble with multiple periodic signal structure in frame are simple but effective. Based on the Morelli and Mengalia algorithms, an OFDM carrier offset estimation algorithm applicable to IEEE802.11a OFDM WLAN system is proposed to obtain estimator performance limits. Furthermore, two algorithms both capable of combining the estimation results of short and long training sequencs of OFDM frame to obtain the overall frequency offset are also presented. Computer simulations have shown both estimators can improve estimation performance significantly.