Maximum Likelihood Carrier Frequency Offset and Symbol Timing Estimation for OFDM Systems with Repeated Training Symbols

• Main Authors: Jiun-Yu Wu, 吳俊育
• Other Authors: Wen-Rong Wu
• Format: Others
• Language: en_US
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/56019988047709327646

碩士 === 國立交通大學 === 電信工程系 === 91 === Abstract OFDM is a favorable modulation scheme for the next generation commercial broadband communication systems since it can effectively mitigate the wireless channel effect. However, OFDM has higher sensitivity to the carrier frequency and symbol timing offsets. A maximum likelihood (ML) method has been proposed in literature to estimate these offsets using two repeated training symbols. In this thesis, we extend the method to obtain the ML frequency offset and symbol timing estimation for Q repeated training symbols where Q is greater than two. An iteration method is also proposed to extend the frequency offset estimation range. Simulations show that the performance of the proposed method can closely approach the Cramer-Rao lower bound. We also apply the proposed method to the 802.11a wireless LAN system and show that the performance of the proposed method can outperform the existing ML method.