| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 99 === Nowadays, direct-conversion radio frequency (RF) receivers become more appealing. However, orthogonal frequency division multiplexing (OFDM) systems with direct-conversion RF receivers are very sensitive to non-idealities at the front-end of receiver, such as I/Q imbalance and carrier frequency o set (CFO). These nonidealities at the receiver result in inter-carrier interference (ICI). Accurate estimates of the non-idealities and channel response are required in OFDM systems. In this thesis, the e ects of I/Q imbalance and CFO on OFDM systems are studied, and the estimation of these parameters is considered. To solve the problems, we propose a time domain method for joint estimation of I/Q imbalance and CFO as well as channel response. The proposed method requires only two OFDM training blocks as a preamble to accomplish joint estimation. Moreover, we do not put any restrictions on the preamble signal and thus the proposed method can be adopted in any communication systems with a preamble. It is shown by simulation results that our proposed method performs well for any channels as long as their order is not longer than cyclic prefix (CP).
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