【正文】 1 CDMA 移動(dòng)通信 RAKE 接收技術(shù)研究 摘要 ： RAKE 接收技術(shù)是 CDMA 擴(kuò)頻通信的關(guān)鍵技術(shù)之一，作為 CDMA 系統(tǒng)中實(shí)現(xiàn)多經(jīng)分集接收的核心部件，它可以分辨出接收信號(hào)中不同的多徑分量，克服多徑衰落，提高系統(tǒng)性能。RAKE 接收技術(shù)可以在時(shí)間上分辨出細(xì)微的多徑信號(hào)，對(duì)這些分辨出來的多徑信號(hào)分別進(jìn)行加權(quán)調(diào)整、使之復(fù)合成加強(qiáng)的信號(hào)。 本文對(duì)在 CDMA 移動(dòng)通信中的 RAKE 接收機(jī)進(jìn)行了簡要的介紹， 其基本原理是將信號(hào)的多徑分量提取出，對(duì)他們進(jìn)行延遲和相位校正，使之在某一時(shí)刻對(duì)齊，并按一定的規(guī)則進(jìn)行合并，變矢量 合并為代數(shù)合并，有效地利用多徑，提高多徑分集的效果。本文還根據(jù) RAKE接收技術(shù)的原理 設(shè)計(jì)了接收機(jī)的系統(tǒng)框圖， 用三種不同的合并方式， 利用 matlab 實(shí)現(xiàn)了多徑信道的仿真 ， 并賦予了相應(yīng)的說明， 分析 RAKE 接收機(jī)的性能 。 關(guān)鍵詞 ： CDMA ； RAKE 接收 ；多徑 ；分集接收 2 Abstract： The Rake receiver is one key techniques of the CDMA spreading spectrum munication .As for the core part of achieving the multipath diversity reception of CDMA system .It can distinguish the different multipath ponents in received signals ,overe the diversity fading ,and improve the system performance .RAKE receiver technique can distinguish the subtle multipath signals in time domain ,modulate the distinguished signals ,posite into the enhanced signals . This paper has simply introduced the RAKE receiver in CDMA system ,the basic principal is to extract the multipath ponent of signals,and delay them for the phase calibration ,to make the phase identical at some moment,and merge based on some rules . Change the vector bination into the algebra bination to use the multipath effectively and to enhance the effect of the multipath diversity . The paper also designs the system block diagram of the RAKE receiver by three different bining methods , and achieve the simulated multipath channel by matlab and containing some corresponding notes . Key words: CDMA 。 RAKE receiver 。 multipath 。 diversity reception 。 3 目錄 CDMA 移動(dòng)通信 RAKE 接收技術(shù)研究 .................................................................................... 1 目錄 ................................................................................................................................. 3 1 緒論 ............................................................................................................................. 4 所選課題的目的和意義 ....................................................................................... 4 國內(nèi)外研究現(xiàn)狀 ................................................................................................. 5 本文的研究內(nèi)容及安排 ....................................................................................... 6 2 CDMA 的基本原理 ........................................................................................................... 7 碼分多址基本概念 .............................................................................................. 7 CDMA 通信系統(tǒng)的優(yōu)點(diǎn) ......................................................................................... 8 抗干擾能力強(qiáng) ........................................................................................... 8 系統(tǒng)容量大 .............................................................................................. 8 軟容量 ..................................................................................................... 8 保密性強(qiáng) ................................................................................................. 8 高的話音質(zhì)量和低的發(fā)射功率 .................................................................. 8 易于實(shí)現(xiàn)精確定時(shí)與測距 ......................................................................... 8 多址技術(shù) ............................................................................................................ 9 時(shí)分多址 （ TDMA） ................................................................................. 9 頻分多址 （ FDMA） ................................................................................. 9 碼分多址 （ CDMA） ................................................................................10 擴(kuò)頻技術(shù) ...........................................................................................................10 3 RAKE 接收技術(shù) ..........................................................................................................12 RAKE 接收機(jī)及其譯名 .................................................................................12 RAKE 接收機(jī)的基本原理 ..............................................................................13 RAKE 接收機(jī)的數(shù)學(xué)實(shí)現(xiàn)模型 .......................................................................16 RAKE 接收機(jī)誤碼性能分析 ..........................................................................19 4 RAKE 接收機(jī)的仿真 ....................................................................................................23 初狀態(tài)設(shè)定 ................................................................................................23 MATLAB 性能仿真 ........................................................................................24 MATLAB 仿真結(jié)果及分析 ..........................................................................24 5 總結(jié)與展望 ..................................................................................................................26 本文所做的工作 .........................................................................................26 CDMA 通信系統(tǒng)中 RAKE 接收技術(shù)的展望 .........................