寬頻通訊系統中實虛部非協調、載波頻率位移、相位雜訊與通道響應之同估測

Abstract

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, carrier frequency offset (CFO), and phase noise (PHN). These non-idealities 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 effects of I/Q imbalance, CFO, and PHN 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, CFO, and PHN as well as channel response. The proposed method requires only one OFDM training block 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).