【正文】 延遲，經(jīng)加權(quán)調(diào)制和正交載波相乘輸出正交分量。為下章具體設(shè)計(jì)電路仿真做鋪墊。[7]根據(jù)MSK調(diào)制電路的原理以及電路圖，用函數(shù)信號(hào)發(fā)生器產(chǎn)生，兩路信號(hào)，分別經(jīng)過(guò)兩個(gè)乘法器，然后對(duì)兩路信號(hào)進(jìn)行數(shù)據(jù)加權(quán)，再通過(guò)帶通濾波器進(jìn)行正交載波調(diào)制即可得到MSK信號(hào)。由約束條件： 可得到相位常數(shù)與差分編碼后的碼元序列的關(guān)系如表1所示。 總結(jié)上述分析即仿真過(guò)程，說(shuō)明了圖41確實(shí)可以構(gòu)成最小移頻鍵控系統(tǒng)，為構(gòu)造實(shí)際的系統(tǒng)獲取了一定的先驗(yàn)知識(shí)，提高了系統(tǒng)的研制效率。59結(jié)論 結(jié) 論當(dāng)今信息時(shí)代，對(duì)于信息的傳輸數(shù)字通信已經(jīng)成為重要手段。經(jīng)過(guò)分析各個(gè)波形特征得出MSK信號(hào)是包絡(luò)恒定的，并且在兩個(gè)碼元相接處，相位是連續(xù)的。而通信信號(hào)的數(shù)字調(diào)制技術(shù)也引起了人們的廣泛關(guān)注。二、研究的基本內(nèi)容，擬解決的主要問(wèn)題： MSK是對(duì)FSK信號(hào)作某種改進(jìn)，使其相位始終保持連續(xù)不變的一種調(diào)制。本文主要研究其數(shù)字調(diào)制電路的設(shè)計(jì)與仿真，研究特點(diǎn)，分析其誤碼性能。14—15周完成性能分析。SK是一種性能優(yōu)越的新型數(shù)字調(diào)制方式,在外軍的地域通信網(wǎng)中廣泛采用。隨著超大規(guī)模集成電路(VLSI)技術(shù)和計(jì)算機(jī)技術(shù)的飛速發(fā)展，數(shù)字信號(hào)處(DSP)技術(shù)在通信領(lǐng)域中己有了廣泛的應(yīng)用。數(shù)字通信的快速發(fā)展，越來(lái)越普及，研究人員對(duì)其相關(guān)技術(shù)投入了極大的興趣。再者，隨著通信技術(shù)的快速發(fā)展，業(yè)務(wù)量急劇增加，頻帶資源日趨緊張，因而調(diào)制技術(shù)及調(diào)制信號(hào)應(yīng)具有較強(qiáng)的抗干擾能力，信號(hào)占用帶寬小。他們提供多元化及編碼增益而不犧牲的全部傳輸速率. 設(shè)計(jì)標(biāo)準(zhǔn)為時(shí)空編碼分別獲得小額和大額多樣性訂單。在[12] ,時(shí)空編碼基于MSK一直認(rèn)為, 那里的多樣性贏得了用偏置調(diào)制格式. 自MSK可以視為一個(gè)線性正交調(diào)制[ 9,11 ] 傳統(tǒng)的標(biāo)準(zhǔn)給予線性調(diào)制,可直接用于設(shè)計(jì)時(shí)空碼msk . 按照這一辦法,在本文中, 我們?cè)O(shè)計(jì)的空時(shí)格碼MSK使用兩名和三名天線傳輸標(biāo)準(zhǔn)的基礎(chǔ)上給予[1,2] 準(zhǔn)靜態(tài)瑞利衰落. 然后通過(guò)計(jì)算機(jī)模擬，我們核對(duì)他們的良好表現(xiàn). 本文安排如下. 在第2節(jié)我們描述了系統(tǒng)模型,在考慮之列. 第3列時(shí)空MSK碼和第4列仿真結(jié)果的建議代碼. 結(jié)論是,在第5 部分. 我們假設(shè)MSK的n個(gè)區(qū)間信號(hào)s(t,b)的傾斜相位在[11,13]中給出為象征期限和b={bn}是修改信息序列bn 2{0,1}。這導(dǎo)致MSK時(shí)間不變兩相態(tài)格走勢(shì)的強(qiáng)弱(一) . 美國(guó)在格標(biāo)記的價(jià)值觀相的hn作為初始狀態(tài).枝干上標(biāo)記的符號(hào)MSK 0正?；男盘?hào)星座列磁鐵(二) . 這些符號(hào)對(duì)應(yīng)的單位能源(權(quán)證=1 ) MSK波形,在時(shí)間間隔 [0,Ts],作為。已連續(xù)階段,每幀的起始和結(jié)束(終止用鉆頭在STMSK編碼) ,在零相位狀態(tài). 這一制度提供了一個(gè)信息率鉀/技比特/,以獲得高傳輸率可利用此系統(tǒng),就應(yīng)該增加 ,我們唯一考慮的情況下, K值為1 , STMSK碼給出已整(相同壓縮MSK)信息率1比特/秒. 經(jīng)過(guò)相干解調(diào),相應(yīng)的序列從接收到。我們假定Viterbi算法基于柵格STMSK聘請(qǐng)解碼的接收機(jī). 在理想信道狀態(tài)信息的情況下,分支度量用的解碼STMSK一個(gè)過(guò)渡標(biāo)記給出了. 常規(guī)的空時(shí)碼設(shè)計(jì)準(zhǔn)則在準(zhǔn)靜態(tài)衰落,而衰落系數(shù)卻不斷碰到一件框和獨(dú)立 從一個(gè)框架下,最大限度的最低排名( R )和最小行列式(駁回)的距離 興建從所有可能對(duì)獨(dú)特碼. 這里指小時(shí)厄米特運(yùn)行等級(jí)標(biāo)準(zhǔn)是用來(lái)達(dá)到最大分集增益,而行列式準(zhǔn)則,是用來(lái) 最大的編碼增益,作者證明的業(yè)績(jī)占主導(dǎo)地位的最小平方歐幾里德距離,當(dāng)產(chǎn)品 滿意了,而對(duì)應(yīng)于若干獨(dú)立的子信道,或等效的多樣性,系統(tǒng)有序. 利用上述常規(guī)指引,我們已設(shè)計(jì),由專(zhuān)人全速率, (一)及(二)目前四國(guó)stmsk 格形碼設(shè)計(jì)參數(shù),and ,. 第一次和第二次發(fā)射天線分別分行標(biāo)記的輸出MSK符號(hào)為例, 01個(gè)代表,象征0 轉(zhuǎn)發(fā)是由第一天線和1符號(hào)傳播的,但我們將證明,在接下來(lái)的一段,原代碼提供更好的性能, (一)及(二)本STMSK碼參數(shù)分別為 , and ,這些代碼有更好的行列式和歐幾里德距離價(jià)值觀, STMSK代碼提供全面多樣化已找到. 我們也調(diào)查stmsk碼傳送三個(gè)天線的四態(tài)案件,沒(méi)有STMSK典滿秩與行列式較大 ,我們已經(jīng)取得了STMSK代碼所示qNs的( a )與參數(shù),and 。Space–time coding。From (b),it is seen that tiltedphase has a biorthogonal signal constellation identical to ,needless to say that it provides lower spectral sidebands than QPSK in the power spectrum due to the phase uncoded MSK scheme presented above has an information rate of 1/Ts bits/s.Now,let us consider a munication system employing nT antennas at the transmitter and antennas at the receiver as in this system,data is encoded by a space–time MSK (STMSK)encoder,which generates nT parallel streams of MSK symbols preserving the phase continuity for each fact,the STMSK encoder consists of a ratek/nT channel encoder followed by nT MSK modulators for each output bits of the channel encoder where k is the number of input bits of the ,in this paper,we only consider the bined structure,.,the STMSK encoder and its trellis,and do not pursue investigation of the cha。Minimum shift keyingOver the past several years,there has been a great deal of research to improve performance of wireless munications systems,where multipath fading usually has a severe impact on the error –time trellis codes have been introduced to improve the error performance as well as the information rate of wireless systems using multiple antennas[1].They provide diversity and coding gains without sacrificing the full transmission design criteria for space–time codes were given in[1,2]for small and large diversity orders, the literature,several space–time trellis codes that provide good diversity and coding advantage have been presented for linear modulations such as phase shift keying(PSK).Continuous phase modulation(CPM)is a signaling method that provides low spectral occupancy due to its phase continuity[8,9].It generates constant envelope waveforms and allows the lowcost nonlinear transmitter amplifier to operate at peak output has also memory and thus an inherent code structure which can be used to mitigate against advantages make CPM very attractive modulation scheme for wireless power efficiency of CPM can be further improved by bining it with space–time coding,while maintaining the full transmission ,space–time code design for CPM is more dicult than the linear modulation case due to the nonlinearity and more plex resulting performance and Fitz[10]recently presented space–time trellis coding for CPM systems and introduced the design criteria to enable linear deposition of CPM signals,they were able to identify some general code construction with CPM.A special type of CPM is minimum shift keying(MSK)which has rectangular frequency pulse shape and modulation index of is of practical importance in wireless munications,due to its simplicity besides the constant envelope,bandwidth and power efficiency advantages[11].In[12],space–time coding based on MSK has been considered,where the diversity gain is obtained by using an offset modulation MSK can be viewed as a quadrature linear modulation[9,11],the conventional criteria given for linear modulations can be directly used in the design of space–time codes for this approach,in this paper,we design space–time trellis codes for MSK employing two and three transmit antennas based on the criteria given in[1,2]for quasistatic Rayleigh fading then verify their good performance by puter simulations.The paper is organized as Section 2 we describe the system model under 3 presents the space–time MSK trellis codes and Section 4 presents simulation results of the proposed are given in Section 5. modelWe consider the‘‘tilted phase’’MSK whose signal s(t,b)for nth interval is given by[11,13]where Es is the symbol energy,Ts is the symbol duration and b={bn}is the‘‘modified’’information 2{0,1}denotes the modified nth information symbol which is defined as bn=(an+1)/2 where an 2{177。received in revised form 15 April 2005。是衰落系數(shù)的路徑,從發(fā)射天線i到j(luò)并且是添加劑噪聲等效為獨(dú)立樣本的一個(gè)零均值復(fù)高斯隨機(jī)過(guò)程方差N0/2每維。符號(hào)傳播的同時(shí),從每一個(gè)不同的發(fā)射天線和所有的符號(hào)有相同的傳輸區(qū)間時(shí)空矩陣碼被轉(zhuǎn)換。修改載波頻率f1被定義為fc 1/4Ts, fc為載波頻率。連續(xù)相位調(diào)制( CPM )的是一個(gè)信號(hào)的方法,提供低頻譜占用由于其相連續(xù)性。五、主要參考文獻(xiàn)：1 Multisim User Guide [S].In teractive Inage Technology Ltd,Canada,19992 林輝，：武漢理工大學(xué)出版社，20023 鄭步生， ：電子業(yè)出版社，20024 ：國(guó)防工業(yè)出版社