【正文】 FDM 系統(tǒng)的傳輸模型 ...............................................................................11 無(wú)線信道特征.................................................................................................12 大尺度衰落...........................................................................................13 小尺度衰落...........................................................................................14 信道模型.........................................................................................................16 AWGN 信道模型 .................................................................................16 無(wú)線多徑信道模型...............................................................................16 本章小結(jié)........................................................................................................16第三章 一種基于門限判決的 LS 估計(jì)算法 OFDM 導(dǎo)頻方式 ............................................................................................18 估計(jì)算法........................................................................................................19 LS 算法 ................................................................................................20 MMSE 算法和 LMMSE 算法 ............................................................21 SVD 算法 ............................................................................................22 基于門限判決的 LS 估計(jì)算法 .....................................................................23 理論依據(jù)..............................................................................................23 算法改進(jìn)..............................................................................................25 仿真及分析....................................................................................................27 本章小結(jié)........................................................................................................27第四章 一種三次 hermite 插值算法 常見的插值算法.............................................................................................30 線性插值...............................................................................................31 高斯插值...............................................................................................31 DFT 插值 ..............................................................................................32 三次樣條插值算法..............................................................................32 三次 hermite 插值算法 ..................................................................................33 算法的設(shè)計(jì)..........................................................................................33 算法的應(yīng)用..........................................................................................36 仿真及分析.....................................................................................................39 最佳導(dǎo)頻距離.......................................................................................42 多普勒頻移對(duì)誤碼率的影響...............................................................43 多徑效應(yīng)對(duì)誤碼率的影響...................................................................44 本章小結(jié)........................................................................................................45結(jié)束語(yǔ)........................................................................................................................46參考文獻(xiàn) ...................................................................................................................47致 謝........................................................................................................................51附錄 A 攻讀學(xué)位期間所發(fā)表的學(xué)術(shù)論文 .....................................................52第一章 緒論 OFDM 信道估計(jì)的研究背景及意義正交頻分復(fù)用作為第四代（4G）無(wú)線通信系統(tǒng)的主要技術(shù)在高速無(wú)線傳輸中具有許多優(yōu)勢(shì)，OFDM 是一種利用多載波并行傳播數(shù)據(jù)的技術(shù) [12]，近年來 OFDM 技術(shù)受到國(guó)內(nèi)外無(wú)數(shù)學(xué)者的關(guān)注，此技術(shù)的特點(diǎn)是通過若干個(gè)互相正交的子載波將高速的數(shù)據(jù)變成低速的數(shù)據(jù)，然后在進(jìn)行傳輸，根據(jù)子載波間的互相正交性，發(fā)送端的信號(hào)可以無(wú)干擾的還原，而且 OFDM 技術(shù)由于子載波之間是互相正交重疊的，所以這就大大節(jié)約了帶寬，提高了頻譜的利用率。關(guān)鍵詞：正交頻分復(fù)用；信道估計(jì)；誤碼率；基于門限判決的最小二乘算法；三次埃爾米特插值 ABSTRACTWith social progress and development, the wireless broadband digital munication system and cause broad researchers interests. Pilot interpolation algorithm research of OFDM technology caused extensive concern at home and abroad, the first thing is to put the known pilot signals to insert each subcarrier, using leastsquare estimation, least meansquare error estimation and singular value deposition estimation to estimate the pilot points channel response, then by linear interpolation, gaussian interpolation, DFT interpolation, Cubicspline interpolation etc interpolation algorithms estimate pilot subcarrier channel response, in order to further reduce the BER, improve the performance of the system, interpolation algorithm has bee OFDM technology focus. This paper in order to reduce BER and improve the performance of the system, puts forward a new interpolation algorithm. main research work of this paper are as follows: (1) Aiming at OFDM channel characteristic, establishes mathematical model of wireless channels. Based on which this paper is indepth discussions of block and b two pilot. Discusses LS, MMSE and SVD algorithm, and pare linear interpolation with gaussian interpolation, DFT interpolation, Cubicspline interpolation performance, and analyzes the reasons of high BER algorithm, in order to put forward the improved algorithm to lay the foundation. (2) Aiming at the factor of noise isn’t considered in the LS algorithm, affects estimated accuracy, this paper proposes an based on the threshold judgment LS algorithm, this algorithm will limit time channel response of LS to less than cycle prefix length, and set up a threshold, set zero when the noise ponents within cycle the prefix length and invalid diameter response , which improves the estimated accuracy. (3) Aiming at high BER problem in the existing interpolation algorithm, this paper proposes cubic hermite interpolation algorithm, cubic hermite interpolation uses two nearby pilot point chann