| Summary: | 碩士 === 中原大學 === 電子工程研究所 === 95 === Orthogonal Frequency Division Multiplexing (OFDM) has been widely applied to several mobile radio communication systems, DVB, DAB, and Wireless LAN recently during the development of communication system. OFDM technique is an effective transmission scheme to cope with many channel impairments compared to other multi-carrier communication systems. For example, it offers better performance under multi-path fading channels, yielding higher spectral efficiency and may reduce the effects of inter-symbol interference (ISI). However, OFDM is highly sensitive to carrier frequency offset, which may easily cause each sub-carrier in the system to lose orthogonality and therefore lose its original outstanding performance. Owing to the importance of carrier frequency offset to OFDM, this paper, several non-data-aided frequency synchronization algorithms are compared. In addition , we propose a maximum likelihood (ML) estimation of the CFO in the presence of virtual carriers. Simulation results show that the proposed algorithm performs well for reasonable SNR values. This paper will be ended in the suggestion of frequency offset estimation of OFDM. This research is done under the expectation to be beneficial to future studies for the researchers who have the same interests in this field.
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