Abstract
OFDM is a promising technique in the Universities and research laboratories all over the world. OFDM has been accepted for the Wireless Local Area Network (WLAN) from IEEE 802.11, the Digital Audio Broadcasting (DAB), etc. OFDM can resist multi-path by the cyclic prefix. However, when there is frequency mismatch between the oscillators of the transceivers, the orthogonality corrupts. With the corruption of orthogonality, the Inter Carrier Interference occurs, which increases the BER. Thus, Carrier Frequency Offset is a practical problem for OFDM. There have been many methods proposed to combat the CFO. For example, the cyclic prefix based method in time domain, the pilot based method in frequency domain, and the training symbol based method for initial tracking, etc. In this paper, we propose a pilot based method which is based on PTAW. The most difficult part of CFO estimation in frequency domain is the existence of ICI. Thus, by observing the regularity of each OFDM symbol block, we can find a circulant matrix with low complexity to cancel the ICI. After canceling the ICI, we will have a more accurate estimate than PTAW.