本文選題：脈沖噪聲　切入點(diǎn)：正交頻分復(fù)用　出處：《西安電子科技大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：正交頻分復(fù)用(OFDM)作為一種特殊的多載波傳輸方案,以其高效的頻譜利用率和較強(qiáng)的抗多徑能力等特點(diǎn),廣泛應(yīng)用于軍事和民用通信中。OFDM系統(tǒng)的參數(shù)估計問題一直以來是通信領(lǐng)域的研究熱點(diǎn),研究該問題具有重要的理論意義和實際的應(yīng)用價值。常規(guī)的OFDM信號參數(shù)估計方法將背景噪聲建立為高斯模型,但是近年來的研究發(fā)現(xiàn),由于實際無線通信環(huán)境中普遍存在的一些自然和人為噪聲源,諸如閃電,雷擊,汽車點(diǎn)火和外臺信號等,信道噪聲常常伴有顯著的短時大幅度脈沖,這種噪聲可用Alpha穩(wěn)定分布模型精確描述。在這類非高斯噪聲背景下,常規(guī)的OFDM系統(tǒng)的參數(shù)估計方法性能退化甚至失效。因此,本文將重點(diǎn)研究Alpha穩(wěn)定分布噪聲下OFDM系統(tǒng)的參數(shù)估計問題。在OFDM系統(tǒng)中,多普勒效應(yīng)和收發(fā)兩端本振頻率不匹配等因素通常會引起頻率偏移。由于OFDM對頻率偏移非常敏感,因此,頻率偏移估計是OFDM系統(tǒng)的關(guān)鍵技術(shù)之一。在Alpha穩(wěn)定分布噪聲中,常規(guī)頻率偏移估計的方法性能退化。針對這一問題,本文提出了一種基于Myriad濾波的頻率偏移改進(jìn)算法。Myriad濾波是一種適用于Alpha穩(wěn)定分布隨機(jī)過程的非線性濾波方法,對脈沖噪聲具有較好的抑制作用。因此,本文提出的算法首先采用加權(quán)Myriad濾波器對接收信號進(jìn)行濾波處理,減小脈沖噪聲對參數(shù)估計的影響,然后結(jié)合SC算法的頻率偏移估計思想,依次估計出OFDM系統(tǒng)的小數(shù)倍頻率偏移和整數(shù)倍頻率偏移。仿真結(jié)果表明,在Alpha穩(wěn)定分布噪聲下,該方法具有良好的估計性能。OFDM信號的時域參數(shù)估計對通信對抗、非協(xié)作通信、無線電頻譜監(jiān)測等領(lǐng)域具有重要的意義,本文針對常規(guī)OFDM信號時域參數(shù)估計方法在Alpha穩(wěn)定分布噪聲環(huán)境下性能退化的問題,提出了一種基于相關(guān)熵的時域參數(shù)估計新方法。相關(guān)熵是適用于非高斯信號處理的一種廣義相關(guān)函數(shù),用于表征隨機(jī)變量的局部相似性。本文提出的方法利用OFDM信號的時域結(jié)構(gòu)具有局部相似性這一特點(diǎn)以及相關(guān)熵對脈沖噪聲較好的抑制作用,完成Alpha穩(wěn)定分布噪聲下OFDM信號有用符號時間和符號周期這兩個時域參數(shù)的估計。此外,為進(jìn)一步提高強(qiáng)脈沖噪聲下有用符號時間和符號周期的參數(shù)估計性能,本文利用累積法對該方法進(jìn)行了改進(jìn)。
[Abstract]:As a special multi-carrier transmission scheme, orthogonal Frequency Division Multiplexing (OFDM) is characterized by its high spectral efficiency and strong anti-multipath capability. The parameter estimation of .OFDM system is a hot topic in the field of communication, which is widely used in military and civil communications. It has important theoretical significance and practical application value to study this problem. The conventional OFDM signal parameter estimation method establishes the background noise as Gao Si model, but in recent years, it has been found that, Because of some natural and man-made noise sources, such as lightning, lightning strike, automobile ignition and outstation signals, the channel noise is often accompanied by significant short and large pulses. This kind of noise can be accurately described by Alpha stable distribution model. Under the background of this kind of non-#china_person0# noise, the performance of the conventional parameter estimation method for OFDM system degenerates or even fails. In this paper, we will focus on the parameter estimation of OFDM system under the stable distributed noise of Alpha. In OFDM system, the Doppler effect and the mismatch of the local oscillator frequency at both ends of the transmitter and receiver usually cause the frequency offset. Because the OFDM is very sensitive to the frequency offset, Therefore, frequency offset estimation is one of the key techniques in OFDM systems. In Alpha stable distributed noise, the performance of conventional frequency offset estimation methods is degraded. This paper presents an improved frequency offset algorithm based on Myriad filter. Myriad filter is a nonlinear filtering method suitable for Alpha stable distribution stochastic process. The proposed algorithm firstly uses weighted Myriad filter to filter the received signal to reduce the influence of impulse noise on parameter estimation, and then combines the frequency offset estimation idea of SC algorithm. The fractional frequency offset and integer multiple frequency offset of OFDM system are estimated in turn. The simulation results show that the proposed method has good estimation performance under stable distributed noise of Alpha signal. Radio spectrum monitoring is of great significance. In this paper, the performance degradation of conventional time-domain parameter estimation methods for OFDM signals in Alpha stable distributed noise environment is discussed. A new time-domain parameter estimation method based on correlation entropy is proposed. Correlation entropy is a generalized correlation function suitable for non-#china_person0# signal processing. This method is used to characterize the local similarity of random variables. Based on the characteristic of local similarity in time domain structure of OFDM signal and the good suppression effect of correlation entropy on impulse noise, The time domain parameters of useful symbol time and symbol period of OFDM signal under Alpha stable distributed noise are estimated. In addition, in order to further improve the performance of parameter estimation of useful symbol time and symbol period under strong impulse noise, In this paper, the cumulation method is used to improve the method.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN911.23;TN929.53

【共引文獻(xiàn)】

相關(guān)博士學(xué)位論文 前3條

1 趙知勁;統(tǒng)計通信信號處理技術(shù)研究[D];西安電子科技大學(xué);2009年

2 郭瑩;穩(wěn)定分布環(huán)境下的時延估計新方法研究[D];大連理工大學(xué);2009年

3 單志明;α穩(wěn)定分布參數(shù)估計及自適應(yīng)濾波算法研究[D];哈爾濱工程大學(xué);2012年

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本文編號：1605717