【正文】 % BER for uncoded QPSK input PPsqostbc(kk) = *erfc(sqrt(*SNRsqostbc))。 h339。S(1) S(1) S(1)1]。 S(1) 1 S(1) S(1)。 h239。 % subchannels %%%% QuasiOrthogonal STBC % equivalent channel HH_o = [h1 h2 h3 h4。 for SNRdB=SNRdBvalues SNRdB SNRidx = SNRidx + 1。,3) grid hold off % 圖 42 clear all % number of channel realizations. This number needs to be increased when % estimating small probabilities %It = 50000。) ylabel(39。,1) semilogy(SNRdBvalues, Postbc,39。 華僑大學(xué)廈門(mén)工學(xué)院 畢業(yè)設(shè)計(jì)（論文） 30 end % average over channel realizations Postbc(SNRidx) = mean(PPostbc) Pqostbc(SNRidx) = mean(PPqostbc) Psiso(SNRidx) = mean(PPsiso) end figure(1) semilogy(SNRdBvalues, Psiso,39。 h139。 h239。 h239。 h439。 h3 h4 h1 h2。 % SNR index SNR = 10^(SNRdB/10)。 It = 1000。執(zhí)行編碼在兩個(gè)時(shí)空領(lǐng)域引入相關(guān)性在不同時(shí)期各天線信號(hào)傳播。 華僑大學(xué)廈門(mén)工學(xué)院 畢業(yè)設(shè)計(jì)（論文） 26 附錄：英文文獻(xiàn)及翻譯 A MIMO channel can be realized with multielement array particular interest are propagation scenarios in which individual channels between given pairs of transmit and receive antennas are modelled by an independent flat Rayleigh fading the digital mobile munication technology rapid development and application of today, in order to meet people for a variety of mobile munications business, especially in the broadband data munication needs of the business, mobile munications must improve the quality of munication, try our best to meet the demand of the people. Because of digital mobile munication channel multipath fading channel, the transmission quality of signal in the channel affected by a lot. Receiving signals in the frequency domain and time domain extension cause signal SNR significantly lower for ordinary voice munication, the impact is limited, but for is very strict on bit error rate of data munication, such influence is intolerable. Spacetime coding is based on introducing joint correlation in transmitted signals in both the space and time this approach ,simultaneous diversity and coding gain can be obtained,a well as high spectral .The initial research focused on desigh of joint spacetime dependencies in transmitted singals with the aim of optimizing the coding and diversity gains. An effective and practical way to approaching the capacity of multipleinput multipleoutput(MIMO)wireless channels is to employ spacetime(ST) coding is a coding technique designed for use with multiple transmit is performed in both spatial and temporal domains to introduce correlation between signals transmitted from various antennas at various time spatialtemporal correlation is used to exploit the MIMO channel fading and minimize transmission errors at the codig can achieve transmit diversity and power gain over spatially uncoded systems without sacrificing the bandwidth .There are various approaches in coding structures,including spacetime block codes(STBC)spacetime trellis codes(STTC),spacetime turbo trellis codes and layered spacetime(LST)codes. A central issue in all these schemes is the exploitation of multipath effects in order to achieve high . The multipleinput multipleoutput(MIMO)channels are mainly based on the theoretical work developed by Telatar and Foschini. These capacity limits highlight the potential spectral efficiency of MIMO channels,which grows approximately linearly with the number of antennas,assuming ideal capacity is expressed by the maximum achievable data rate for an arbitrarily low probability of erro,providing that the signal may be encoded by an arbitrarily long spacetime code. 相關(guān)信道下的準(zhǔn)正交空時(shí)碼的性能分析 27 MIMO 信道可以由多元素的陣列天線實(shí)現(xiàn)，在數(shù)字移動(dòng)通信的技術(shù)及應(yīng)用迅猛發(fā)展的今天，為了滿足人們對(duì)各種移動(dòng)通信業(yè)務(wù)，特別是寬帶數(shù)據(jù)通信業(yè)務(wù)的需求，移動(dòng)通信必須改善通信質(zhì)量，盡力滿足人們的需求。指導(dǎo)老師、同學(xué)和身邊的朋友都給了我許多幫助，在此，我鄭重地向你們表示感謝。 此論文限于畢業(yè)設(shè)計(jì)的時(shí)間和作者的知識(shí)背景，主要研究了相關(guān)信道下的準(zhǔn)正交空時(shí)分組碼的誤碼率性能，并對(duì)其進(jìn)行分析比較。 相關(guān)信道下的準(zhǔn)正交空時(shí)碼的性能分析 23 結(jié)論 本文主要以兩種準(zhǔn)正交空時(shí)分組碼為例，研究相關(guān)信道下的準(zhǔn)正交空時(shí)碼性能，使用Jafarknani 碼和 TBH 碼，根據(jù)準(zhǔn)正交空時(shí)分組碼編碼的方法推出信道編碼，并推推導(dǎo)出相關(guān)信道下矩陣和平均信噪比表達(dá)式，以及 相關(guān)信道下的準(zhǔn)正交空時(shí)碼誤碼率表達(dá)式。并且當(dāng)只有接收相關(guān)或者發(fā)送相關(guān)的時(shí)候準(zhǔn)正交空時(shí)碼的誤碼率重在一起。 相關(guān)信道下的準(zhǔn)正交空時(shí)碼的性能分析 17 圖 45 當(dāng)發(fā)送相關(guān)或接收相關(guān)時(shí)誤碼率曲線（相關(guān)系數(shù) ） 從圖 45與 44 的對(duì)比中可以看出當(dāng)相關(guān)信道下的準(zhǔn)正交空時(shí)碼的相關(guān)系數(shù)偏小的時(shí)候，準(zhǔn)正交空時(shí)碼發(fā)送與接收同時(shí)相關(guān)的時(shí)候準(zhǔn)正交空時(shí)碼的誤碼率會(huì)與只 有發(fā)送相關(guān)或者只有接收相關(guān)的準(zhǔn)正交空時(shí)碼的誤碼率差不多。 在下面的仿真中，采用 4根發(fā)射天線， 1根接收天線的多輸入多輸出 MIMO 系統(tǒng)。但編程卻非常簡(jiǎn)單，而且 Matlab 的計(jì)算精度很高。 Matlab 是一個(gè)高級(jí)的 矩陣 /陣列語(yǔ)言，它 包含 控制語(yǔ)句、 函數(shù) 、數(shù)據(jù)結(jié)構(gòu)、輸入和輸出和面向?qū)ο缶幊烫攸c(diǎn)。使用 MATLAB 分別對(duì)這兩種編碼進(jìn)行分別、分類(lèi)的仿真。（ n 階復(fù)方陣 A的對(duì)稱單元互為共軛，即 A 的共軛轉(zhuǎn)置矩陣等于它本身，則 A是埃爾米特矩陣（ Hermitian Matrix）。 當(dāng)角度擴(kuò)展較窄時(shí)，為了得到較小的相關(guān)系數(shù)，需要較大的天線間距。相關(guān)性是信道特性的一個(gè)重要方面，為此，將重點(diǎn)討論信道中存在的相關(guān)性對(duì)于準(zhǔn)正交空時(shí)碼的影響，從而更實(shí)際客觀地認(rèn)識(shí)準(zhǔn)正交空時(shí)碼的性能優(yōu)勢(shì)。 相關(guān)信道下的準(zhǔn)正交空時(shí)碼的性能分析 7 Jafarkhani 碼 Jafarkhani基于 Alamouti編碼方案構(gòu)造了 4發(fā)射天線方案的準(zhǔn)正交空時(shí)分組編碼矩陣。由于正交空時(shí)分組碼的特性，即發(fā)射矩陣各行之間有正交性，可以得到滿分集增益，有一種情況下利用復(fù)正交設(shè)計(jì)得到的正交空時(shí)分組碼達(dá)不到最大傳輸速率，就是當(dāng)發(fā)射天線數(shù)大于 2的 時(shí)候， [5]。 假設(shè)接收端采用一根接收天線。在第二個(gè)發(fā)射周期中，信號(hào) *2x 從 1號(hào)天線發(fā)射，而 *1x 從 2 號(hào)天線發(fā)射，其中 *1x 是 1x 的復(fù)共軛。 MIMO 技術(shù)有一種最佳處理，這種處理是由空時(shí)編碼和解碼實(shí)現(xiàn)的 [4]，它能通過(guò)多天線發(fā)射數(shù)據(jù)流，接收時(shí)也是用多天線完成，所以可以實(shí)現(xiàn)較高容量。 多輸入多輸出（ MIMO）技術(shù) 多輸入多輸出（ MIMO,MultiInput MultiOutput）技 術(shù)是無(wú)線移動(dòng)通信領(lǐng)域智能天線技術(shù)的重大突破，它是實(shí)現(xiàn)第三代和個(gè)人通信與未來(lái)移動(dòng)通信系統(tǒng)間高數(shù)據(jù)速率，提高傳輸質(zhì)量的重要途徑。 then pare the quasiorthogonal space code sent and receiver simultaneously transmit only when associated with related or receive relevant BER. Finally, the results of simulation using MATLAB. Key Words:quasiorthogonal, MIMO ,Correlated channels ,BER 相關(guān)信道下的準(zhǔn)正交空時(shí)碼的性能分析 V 目 錄 第一章 緒論 ................................................................. 1 通信的發(fā)展 .......................................................... 1 多輸入多輸出（ MIMO）技術(shù) ............................................ 1 第二章 正交與準(zhǔn)正交空時(shí)碼 ................................................... 3 Alamouti 編碼 ........................................................ 3 空時(shí)編系統(tǒng)模型 .......................