梳狀引導信號輔助之多輸入輸出通道動差預估與分析

Abstract

正交多頻分工(OFDM)系統在過去數年間已經成功的應用到許多數位通訊上。在正交分頻多工系統通道偵測上，根據梳狀引導信號(comb-type pilots)的輔助，過去已經提出了許多的方法。在這篇論文中，我們提出了一種創新的引導信號內插法(pilot interpolation)並與其他內插法比較，例如：線性內插(LI)、木條曲線內插(SCI)…。在這方法中，我們利用了通道的頻率響應(CFR)的一階與二階動差，並且時域的低通濾波器是在頻域中完成的，這意味著我們不用多一次的傅立葉轉換，因此可以省下一個快速傅立葉轉換，節省了系統的成本。另一方面，多輸入多輸出(MIMO)與正交分頻多工(OFDM)系統的結合，也就是MIMO-OFDM，近來也是廣泛的應用在數位通訊上。因此，我們提出了一個MIMO-OFDM架構，可以將之前根據單輸入單輸出正交分頻多工系統(SISO-OFDM)所設計的引導信號內插演算法套用於上。 I

Orthogonal frequency division multiplexing (OFDM), has been successfully applied to a wide variety of digital communications applications over the past several years. There is many channel estimation strategies are used in OFDM system with comb-type pilots inserted. This thesis introduces an innovative pilot interpolation method by using the 1st and the 2nd moments of the channel impulse response (CIR) and comparing with other methods, ex. LI, SCI ... In this innovative method, time-domain low-pass filter is implemented in frequency-domain; it means that we don’t have to do another fourier transform. In this way, we can save a FFT block to reduce the system cost. On the other hand, the combinations of multi-input multi-output (MIMO) and OFDM, MIMO-OFDM, is widely applied on digital communication recently. Therefore, we introduce a MIMO-OFDM architecture that can easily apply those pilots interpolation algorithms used in single-input single-output (SISO) OFDM systems.