【正文】 方法在需要DTMF字符終止放音不如第一種方法好，但是在不需要DTMF字符終止放音的時(shí)候，第二種方法又有很大的優(yōu)勢(shì)，因?yàn)椴恍枰邮誅TMF字符，省去了很多的冗余代碼。通過比較上述兩種方法，小組一致決定在播放歡迎詞的時(shí)候，使用第二種方法。因?yàn)檫@種方法更人性化，實(shí)際中不可能叫客戶先按一個(gè)其他的鍵，再按對(duì)應(yīng)功能鍵吧！而在自動(dòng)總機(jī)和語音查詢需要接收DTMF字符，并終止以前的放音時(shí)使用第二種方法。結(jié)論本論文采用基于計(jì)算機(jī)和語音卡的技術(shù)方案實(shí)現(xiàn)語音查詢系統(tǒng)。使得本系統(tǒng)具有如下的一些特色：：系統(tǒng)實(shí)施只需要通用PC和少量的語音卡，而同時(shí)計(jì)算機(jī)技術(shù)的飛速發(fā)展，PC機(jī)的價(jià)格得到大幅度降低，使得系統(tǒng)的實(shí)施成本大大降低。：軟件功能分布技術(shù)和硬件功能分布技術(shù)實(shí)現(xiàn)系統(tǒng)的可靠性。：服務(wù)器和前端工作站采用了分散分級(jí)的主從式結(jié)構(gòu)，使系統(tǒng)在主從端都可以根據(jù)需要采用不同的配置。采用開放式的設(shè)計(jì)思想，使系統(tǒng)可以不斷引進(jìn)新的軟件和硬件技術(shù)，進(jìn)行功能的擴(kuò)展。：系統(tǒng)具有自動(dòng)應(yīng)答服務(wù)功能可為用戶提供一天24小時(shí)的不間斷服務(wù)。若對(duì)本系統(tǒng)加以更深層的改進(jìn)和完善后，能極大地改善企、事業(yè)單位對(duì)客戶的服務(wù)狀況，提供每周7天、每天24小時(shí)的高質(zhì)量、高效率、全方位的服務(wù)，拓寬了企、事業(yè)單位的服務(wù)渠道，提高了企、事業(yè)單位的經(jīng)濟(jì)效益。雖然系統(tǒng)能為客戶提供全天候的查詢服務(wù)，但其查詢方式只支持電話查詢方式，在目前通信方式比較豐富的今天，該系統(tǒng)的服務(wù)方式顯得有些單調(diào)。當(dāng)前Internet、手機(jī)和固話的短消息得到了廣泛的應(yīng)用，開發(fā)和實(shí)現(xiàn)支持Web查詢、手機(jī)固話短消息查詢功能的綜合查詢系統(tǒng)是本課題的進(jìn)一步研究內(nèi)容。總結(jié)與體會(huì)隨著市場(chǎng)競(jìng)爭(zhēng)的日益激烈，語音查詢已經(jīng)成為企業(yè)改善客戶關(guān)系，爭(zhēng)取新客戶戰(zhàn)略的一把利器，它只是一種強(qiáng)有力的商業(yè)競(jìng)爭(zhēng)工具。一個(gè)設(shè)計(jì)良好的語音查詢系統(tǒng)能夠?yàn)榭蛻籼峁┲艿健⒂押?、即時(shí)的服務(wù)，同時(shí)也能提高企業(yè)的工作效率，節(jié)約管理費(fèi)用。而本文所論述的語音查詢系統(tǒng)正是適用于大多數(shù)企業(yè)，特別是中小型企業(yè)來建立一個(gè)屬于企業(yè)自己的電話語音查詢系統(tǒng)。在本次設(shè)計(jì)中，通過查閱了大量與語音查詢有關(guān)的文獻(xiàn)資料和老師的解答，使我對(duì)CTI技術(shù)，IVR技術(shù)，以及對(duì)國內(nèi)外語音查詢的發(fā)展動(dòng)態(tài)有了較全面的認(rèn)識(shí)和了解。通過對(duì)系統(tǒng)的可行性分析，需求分析，功能流程分析，提出了總體解決方案，詳細(xì)設(shè)計(jì)并實(shí)現(xiàn)了語音查詢系統(tǒng)，這讓我對(duì)事件的總體分析能力有了一定的提高。本系統(tǒng)可以無需人工座席，穩(wěn)定、高效、全天候的為客戶提供查詢信息，反饋給用戶準(zhǔn)確的信息。由于水平和時(shí)間有限，本語音查詢系統(tǒng)仍然存在著一些不夠完善的地方，如考慮到成本，系統(tǒng)只是用了四塊語音卡，所以處理能力有限。正如剛才所說的系統(tǒng)的不足之處，通過對(duì)現(xiàn)階段語音查詢的發(fā)展速度以及發(fā)展趨勢(shì)的了解，可以預(yù)測(cè)未來的語音查詢系統(tǒng)一定是朝著網(wǎng)絡(luò)化，多媒體化，模塊化及語音識(shí)別的方向發(fā)展，從而實(shí)現(xiàn)大型企業(yè)綜合語音的解決方案。盡管目前有些技術(shù)還沒有成熟，卻預(yù)示了一個(gè)十分光明的前景，未來語音查詢同Internet技術(shù)將走向融合，這使得語音查詢將有更加廣闊的市場(chǎng)。作為一個(gè)通信類的學(xué)生，本次課程設(shè)計(jì)讓我學(xué)到的不僅僅是理論知識(shí)，更重要的是提高了我處理實(shí)際問題的能力，這對(duì)我以后走上工作崗位打下了良好的基礎(chǔ)。參考文獻(xiàn)[1] Alan Shallowayamp。James . 模式精解. 清華大學(xué)出版社，2004[2] 俞海英，李建東等編著. 數(shù)據(jù)庫應(yīng)用教程. 清華大學(xué)出版社，2008 [3] 李純蓮編著. C實(shí)用開發(fā)教程. 清華大學(xué)出版社，2008[4] 李建忠譯. .NET框架程序設(shè)計(jì). 清華大學(xué)出版社，2003[5] 鐘珞編著. 軟件工程. 清華大學(xué)出版社，2005[6] 蘇俊編著. 軟件工程規(guī)范. 清華大學(xué)出版社，2004[7] 孫學(xué)濤編著. 需求分析. 清華大學(xué)出版社，2004[8] 范立南等編著. SQL Server 2000實(shí)用教程. 清華大學(xué)出版社，2004[9] 蘇俊編著. 邊用邊學(xué)SQL Server. 清華大學(xué)出版社，2007 [10] 任鴻編著. 關(guān)系數(shù)據(jù)庫和SQL編程. 清華大學(xué)出版社，2005[11] 于潤偉編著. C項(xiàng)目實(shí)訓(xùn)教程. 電子工業(yè)出版社，2009[12] 劉慧寧，李清華，劉蕾編著. C程序設(shè)計(jì). 機(jī)械工業(yè)出版社，2009[13] John Sharp編著. sual C2005從入門人到精通. 清華大學(xué)出版社，2006[14] 李建華，劉玉生編著. sual C全程指南. 電子工業(yè)出版社，2008[15] Mark Michaelis編著. C，2008[16] ，2002[17] .[OL].[GB][18] [美]Michael ――CTI與呼叫中心[M].電子工業(yè)出版社，2002[19] Michel White Paper.[OL].[20] 附錄英文翻譯英文原文Journal of Systems Engineering and Electronics ,October 2010,–728Available online at Hybrid pilots assisted channel estimationalgorithm for MIMOOFDM systemsYang Zhang* Jiandong Li,and Lihua PangState Key Laboratory of Integrated Service Networks, Xi dian University, Xi’an 710071,Abstract: A hybrid pilots assisted channel estimation algorithm for multiple input multiple output(MIMO)orthogonal frequency division multiplexing(OFDM)systems under low signaltonoise ratio(SNR)and arbitrary Doppler spread scenarios is proposed. Motivated by the dissatisfactory performance of the optimal pilots (OPs)designed under static channels over multiple OFDM symbols imposed by fast fading channels, the proposed scheme first assumes that the virtual pilot tones superimposed at data locations over specific subcarriers are transmitted from all antennas, then the virtual received pilot signals at the corresponding locations can be obtained by making full use of the time and frequency domain correlations of the frequency responses of the time varying dispersive fading channels and the received signals at pilot subcarriers, finally the channel parameters are derived from the bination of the real and virtual received pilot signals over one OFDM symbol based on least square(LS)criterion. Simulation results illustrate that the proposed method is insensitive to Doppler spread and can effectively ameliorate the mean square error(MSE)floor inherent to the previous method, meanwhile its performance outmatches that of OPs at low SNR region under static channels. Keywords: channel estimation, multiple input multiple output (MIMO),orthogonal frequency division multiplexing(OFDM), optimal pilot, time varying dispersive fading channel.DOI: and related worksThe explosive growth of wireless munications is creating the demand for high speed, reliable, and spectrally efficient munication over wireless medium. There are several challenges in attempts to provide such high quality service in this dynamic environment. These pertain to channel time variation and limited spectral bandwidth available for transmission. Multiple input multiple output (MIMO)system achieves high capacity by transmitting independent information over different antennas simultaneously[1]or employs space time coding techniques to gain diversity[2].On the other hand, orthogonal frequency division multiplexing(OFDM)is a multicarrier approach for high throughput munication systems due to its robustness to frequency selective fading, high spectrum efficiency, low implementation and equalization plexity[3].Therefore, the bination of MIMO and OFDM has been considered as one of the most promising techniques for future wireless munication systems[4]. Channel estimation is crucial since acquisition all of the above merits of MIMOOFDM systems depends on accurate channel state information(CSI).In general, there are two classes of methods available for channel estimation. One is based on pilot symbols that are prior known to the receiver, and the other is blind channel estimation, which typically requires longer data records and entails higher plexity. Hence the pilotbased scheme is attractive in practice. The issue of channel estimation for MIMOOFDM systems has been widely studied. Here we only list some significant literatures to briefly review the achievements in this aspect. In[5],discrete Fourier transform(DFT)based channel estimation using a certain number of significant taps for estimating the channel impulse response (CIR)in time domain was proposed. Despite the efficient putational plexity of this scheme, it could suffer from an error floor caused by a noninteger multipath delay spread, relative to the system sampling period, in the wireless channels, known as model mismatch error. The enhancement and simplification of[5]was proposed in[6] by examining the optimal pilots(OPs)d