【摘要】：OFDM系統(tǒng)能夠成為當(dāng)今最有潛力的一種通信系統(tǒng),是因?yàn)槠渥陨砉逃械目苟鄰侥芰?qiáng)、頻帶利用率較高,適合高速率的數(shù)據(jù)通信環(huán)境。作為OFDM系統(tǒng)的重要技術(shù)之一,信道估計(jì)主要完成信號(hào)從發(fā)射端到接收端的無線信道頻率響應(yīng)的估計(jì)。這對(duì)于克服無線信道的衰落特性,提高接收機(jī)的綜合性能有非常重要的意義和研究?jī)r(jià)值。本文主要研究了OFDM系統(tǒng)的信道估計(jì)技術(shù),并依據(jù)802.11a的幀結(jié)構(gòu),設(shè)計(jì)實(shí)現(xiàn)了系統(tǒng)信道估計(jì)方案。首先介紹了OFDM系統(tǒng)的工作原理,建立了數(shù)據(jù)傳輸?shù)臄?shù)學(xué)模型。依據(jù)無線信道的衰落特性,分析了多徑衰落和多普勒頻移對(duì)信號(hào)傳輸過程的影響。其次,討論了基于OFDM系統(tǒng)的信道估計(jì)方法,重點(diǎn)分析了基于導(dǎo)頻的信道估計(jì)方法。討論了導(dǎo)頻的插入數(shù)量和圖案,研究了導(dǎo)頻位置處的信道估計(jì)和數(shù)據(jù)位置處的插值技術(shù),為后續(xù)設(shè)計(jì)802.11a的信道估計(jì)方案提供依據(jù)。設(shè)計(jì)和實(shí)現(xiàn)802.11a信道估計(jì)方案是本文的重點(diǎn)。依據(jù)802.11a的幀結(jié)構(gòu)和導(dǎo)頻數(shù)量,綜合考慮了信道估計(jì)性能和實(shí)現(xiàn)的可行性,設(shè)計(jì)了基于長(zhǎng)訓(xùn)練序列和導(dǎo)頻綜合的信道估計(jì)方案。對(duì)于長(zhǎng)訓(xùn)練序列的信道估計(jì),采用基于兩個(gè)長(zhǎng)訓(xùn)練序列的LS估計(jì)方法。對(duì)于導(dǎo)頻的信道估計(jì),采用基于LS準(zhǔn)則和線性插值相結(jié)合的信道估計(jì)方案。最后實(shí)現(xiàn)了基于802.11a的OFDM系統(tǒng)的信道估計(jì)方案,并對(duì)估計(jì)模塊進(jìn)行了功能驗(yàn)證和電路驗(yàn)證,以表明了系統(tǒng)信道估計(jì)方案的可行性。結(jié)合幀檢測(cè)、載波同步、定時(shí)同步等模塊進(jìn)行聯(lián)調(diào),驗(yàn)證系統(tǒng)接收端的功能。
[Abstract]:OFDM system can become the most potential communication system because of its strong anti-multipath ability, high bandwidth utilization, and suitable for high-speed data communication environment. As one of the most important techniques in OFDM systems, channel estimation mainly completes the estimation of the wireless channel frequency response from the transmitter to the receiver. It is of great significance and research value to overcome the fading characteristic of wireless channel and improve the comprehensive performance of receiver. This paper mainly studies the channel estimation technology of OFDM system, and designs and implements the channel estimation scheme according to the frame structure of 802.11a. Firstly, the working principle of OFDM system is introduced, and the mathematical model of data transmission is established. According to the fading characteristics of wireless channel, the effects of multipath fading and Doppler shift on the signal transmission process are analyzed. Secondly, the channel estimation method based on OFDM system is discussed, and the channel estimation method based on pilot frequency is analyzed. The number and pattern of pilot insertion are discussed, and the channel estimation at pilot position and interpolation technique at data location are studied, which provides the basis for the subsequent design of 802.11a channel estimation scheme. The design and implementation of 802.11a channel estimation scheme is the focus of this paper. According to the frame structure and pilot number of 802.11a, the channel estimation scheme based on long training sequence and pilot synthesis is designed by considering the performance and feasibility of channel estimation. For the channel estimation of long training sequence, LS estimation method based on two long training sequences is adopted. For pilot channel estimation, a channel estimation scheme based on LS criterion and linear interpolation is proposed. Finally, the channel estimation scheme of OFDM system based on 802.11a is implemented, and the function verification and circuit verification of the estimation module are carried out to demonstrate the feasibility of the channel estimation scheme. Combined with frame detection, carrier synchronization, timing synchronization and other modules to verify the functions of the system receiver.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN929.53

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本文編號(hào)：2185163