本文選題：正交頻分復(fù)用 + 隧道　； 參考：《電子科技大學(xué)》2014年碩士論文

【摘要】：作為下一代移動通信LTE的核心技術(shù),OFDM技術(shù)已經(jīng)經(jīng)歷了多次跨越式的發(fā)展,越來越受到人們的青睞,其應(yīng)用范圍也在不斷地擴(kuò)大。隧道作為一種受限的通信環(huán)境,無線電波在隧道內(nèi)的傳播特性與非受限空間內(nèi)的大不相同。受隧道壁的影響,傳輸環(huán)境中充滿了電波的反射路徑,在接收端產(chǎn)生多徑效應(yīng),嚴(yán)重影響接收端對接收信號的解調(diào),制約了無線通信系統(tǒng)在隧道中的應(yīng)用。OFDM系統(tǒng)以其技術(shù)上的優(yōu)勢,能夠有效地抵抗隧道環(huán)境下的多徑效應(yīng),提高通信質(zhì)量,使其成為隧道環(huán)境下進(jìn)行無線通信的選擇之一。作為OFDM技術(shù)的關(guān)鍵技術(shù)之一,信道估計在OFDM無線通信系統(tǒng)中占有非常重要的位置。通過OFDM信道估計技術(shù),接收端可以獲知無線信道的信息,結(jié)合接收端的均衡器,能夠?qū)邮招盘査?jīng)歷的信道衰落進(jìn)行補償,增強系統(tǒng)對無線信道衰落的抵抗力,提高通信系統(tǒng)的可靠性。本文圍繞OFDM系統(tǒng)在隧道復(fù)雜多徑環(huán)境下的信道估計展開,進(jìn)行以下工作:1)分析無線電波在自由空間中的傳播特性,包括無線電波的傳輸方式、無線電波的空間損耗及小尺度損耗。以此為基礎(chǔ),對隧道環(huán)境下無線電波的傳播特性進(jìn)行探究,分析無線電波在隧道環(huán)境下的傳播損耗模型,然后建立隧道環(huán)境下無線信道的確定型模型和統(tǒng)計型模型,并對兩種模型進(jìn)行仿真分析。2)基于OFDM系統(tǒng)的基本原理、實現(xiàn)技術(shù)及關(guān)鍵技術(shù),從OFDM系統(tǒng)的基帶模型出發(fā),研究OFDM系統(tǒng)基于輔助導(dǎo)頻的信道估計算法和信道插值算法。根據(jù)直通隧道和彎曲隧道環(huán)境下的信道模型,利用Matlab仿真平臺,對信道估計中的LS算法、MMSE算法、SVD算法以及基于小波降噪的信道估計算法在兩種隧道環(huán)境下的估計性能作仿真和分析,并在直通隧道環(huán)境下對常數(shù)插值、線性插值、多項式插值、樣條插值算法以及基于DFT的信道插值算法的插值性能進(jìn)行分析和比較。3)研究基于DFT的信道算法,對尾部補零和降噪處理兩種時域處理方式做了深入的研究和仿真分析。在此基礎(chǔ)上,針對LS算法中易受噪聲干擾的技術(shù)弊端,對基于DFT時域降噪的信道估計算法進(jìn)行改進(jìn),根據(jù)信道響應(yīng)中的噪聲信號和有用信號設(shè)定閾值門限,對循環(huán)前綴內(nèi)的信道響應(yīng)作二次降噪處理。仿真結(jié)果表明,與傳統(tǒng)時域降噪算法相比,改進(jìn)后的算法能夠獲得3~6dB的性能提高。
[Abstract]:As the core technology of the next generation mobile communication LTE technology has experienced many leaps and bounds development and has been more and more favored by people and its application scope is also expanding. As a limited communication environment, the propagation characteristics of radio waves in tunnels are quite different from those in unconfined space. Under the influence of the tunnel wall, the transmission environment is filled with the reflection path of the radio wave, which produces the multipath effect at the receiving end, which seriously affects the demodulation of the received signal at the receiving end. It restricts the application of wireless communication system in tunnel. OFDM system can effectively resist the multipath effect in tunnel environment and improve the communication quality, making it one of the choices of wireless communication in tunnel environment. As one of the key technologies of OFDM, channel estimation plays an important role in OFDM wireless communication systems. Through the OFDM channel estimation technology, the receiver can get the information of the wireless channel, combined with the equalizer of the receiver, it can compensate the channel fading experienced by the received signal, and enhance the system's resistance to the wireless channel fading. Improve the reliability of communication system. In this paper, the channel estimation of OFDM system in complex multipath tunnel environment is carried out. The following work is done: 1) analyzing the propagation characteristics of radio waves in free space, including the transmission mode of radio waves. Space loss and small scale loss of radio waves. On this basis, the propagation characteristics of radio waves in tunnel environment are explored, and the propagation loss model of radio waves in tunnel environment is analyzed. Then, the deterministic and statistical models of wireless channel in tunnel environment are established. Based on the basic principle of OFDM system, the realization technology and the key technology, the channel estimation algorithm and channel interpolation algorithm based on auxiliary pilot in OFDM system are studied based on the baseband model of OFDM system. According to the channel model under the environment of through tunnel and curved tunnel, the Matlab simulation platform is used. This paper simulates and analyzes the estimation performance of LS algorithm MMSE algorithm and channel estimation algorithm based on wavelet denoising in two tunnel environments, and interpolates constants, linear interpolation, polynomial interpolation in through tunnel environment. The interpolation performance of spline interpolation algorithm and channel interpolation algorithm based on DFT are analyzed and compared. The channel algorithm based on DFT is studied and simulated. On this basis, the channel estimation algorithm based on DFT time domain noise reduction is improved, and the threshold is set according to the noise signal and useful signal in the channel response. The channel response within the cyclic prefix is reduced by quadratic noise reduction. The simulation results show that compared with the traditional time domain noise reduction algorithm, the improved algorithm can improve the performance of 3~6dB.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN929.53

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

1 王艷芬;于洪珍;張傳祥;;礦井超寬帶復(fù)合衰落信道建模及仿真[J];電波科學(xué)學(xué)報;2010年04期

2 張申;帳篷定律與隧道無線數(shù)字通信信道建模[J];通信學(xué)報;2002年11期

，

本文編號：1871302