先導訊號輔助式之正交分頻多工通信系統通道估測設計

Abstract

在本篇論文中，我們研究了正交分頻多工通信系統的通道估測及等化。在論文的第一部分，我們比較了不同通道內插估測方法在IEEE 802.16a和DVB-T通信系統中的表現效能包括線性、Lagrange、cubic spline、cubic Bspline、DFT-based和DCT-based內插器;而發現線性及cubic Bspline內插器有著較佳的位元錯誤比率。如果同時考量運算複雜度的話，通道估測採用線性內插器是一個較佳的選擇。在論文的第二部分，我們研究了由快速衰減通道和載波頻率偏差造成的頻道之間相互干擾對正交分頻多工通信系統的影響。根據通道線性變化的假設，參考現有的方法，我們提出一個能夠有效減低頻道之間相互干擾的估測方法。

In this thesis, channel estimation and equalization for the Orthogonal Frequency Division Multiplexing (OFDM) system are investigated. In the first part of the thesis, we compare the performance of different channel interpolation schemes in IEEE 802.16a and DVB-T systems inclusive of linear, Lagrange, cubic spline, cubic Bspline, DFT-based, and DCT-based interpolators. As a result, linear and cubic Bspline interpolators show better bit error rate. Concerning the computational complexity as well as the performance, the linear interpolator is considered as a proper choice for channel estimation. In the second part of this thesis, we investigate the effect of inter-carrier interferences (ICI) caused by fast fading channels and carrier frequency offsets., According to the linear assumption of channel impulse response, we propose an estimation method that can reduce the ICI effect efficiently based on a current channel estimation method.