【摘要】：在正交頻分復(fù)用(OFDM,Orthogonal Frequency-division Multiplexing)通信中,加入循環(huán)前綴(CP,Cyclic Prefix)是為了確保其子載波在符號(hào)周期內(nèi)的彼此正交,以及多徑引起的符號(hào)間干擾(ISI,Intersymbol Interference)減小。在普通通信環(huán)境下,信道的最大時(shí)延擴(kuò)展(MDS,Maximum Delay Spread)長(zhǎng)度小于CP時(shí)長(zhǎng),則能夠有效的減小ISI,通信性能可得以保證。然而,對(duì)于極端復(fù)雜的多徑環(huán)境,諸如航天艙、地下隧道、潛艇艙等混響腔環(huán)境,MDS將遠(yuǎn)大于常規(guī)的CP時(shí)長(zhǎng),以致傳輸?shù)男盘?hào)波形重疊并且相互影響。如果CP的時(shí)長(zhǎng)不變,則其抑制的ISI能力將失效、系統(tǒng)性能顯著惡化。如果將CP的時(shí)長(zhǎng)變大,則OFDM通信的頻譜資源利用率將大大降低,而且其性能也將下降。本文基于時(shí)間反演(TR,Time Reversal)的時(shí)空聚焦機(jī)制,研究OFDM通信系統(tǒng)中超長(zhǎng)時(shí)延擴(kuò)展(ULDS,Ultra-long Delay Spread)抑制的方法。本文重點(diǎn)研究ULDS信道以及有效的均衡方式。論文的主要工作如下:首先,對(duì)OFDM通信中由于多徑引起的符號(hào)間干擾的抑制方法做了調(diào)研分析,說(shuō)明了本論文研究的必要性。介紹了TR廣泛的應(yīng)用領(lǐng)域。TR技術(shù)的空時(shí)聚焦特性以及抑制信道時(shí)延擴(kuò)展的能力,使其對(duì)ULDS信道下OFDM系統(tǒng)性能的研究具有重要的意義。其次,對(duì)復(fù)雜環(huán)境中多輸入多輸出(MIMO,Multi-input Multiple Output)信道相關(guān)性以及TR與MIMO技術(shù)結(jié)合的通信性能進(jìn)行研究。另外,研究了ULDS信道主瓣與最大旁瓣之比(MSR,Main to Maximum Side-lobe Ratio),分析了在ULDS信道下TR-OFDM的通信性能。得到了在特定的MSR情況下具有良好的通信性能的結(jié)論。對(duì)前置TR和后置TR在復(fù)雜的通信環(huán)境以及簡(jiǎn)單的通信環(huán)境中進(jìn)行仿真研究,得出在ULDS信道下前置TR稍微優(yōu)于后置TR的結(jié)論。最后,對(duì)排序連續(xù)干擾消除(OSIC,Ordered Successive Interference Cancellation)方法進(jìn)行理論分析。在此基礎(chǔ)上,本文提出TR與OSIC結(jié)合的檢測(cè)方法,并且對(duì)比不同排序檢測(cè)的性能。另外,本文提出TR與最小二乘(RLS,Recursive Least Squares)結(jié)合的均衡技術(shù)。通過(guò)Matlab仿真分析,得出TR-RLS均衡技術(shù)對(duì)ULDS的抑制具有一定的作用�？偨Y(jié)了本論文的工作內(nèi)容,對(duì)下一步研究指出方向。
[Abstract]:In orthogonal Frequency Division Multiplexing (OFDM,Orthogonal Frequency-division Multiplexing) communication, cyclic prefix (CP,Cyclic Prefix) is added to ensure that its subcarriers are orthogonal to each other in the symbol period, and the inter-symbol interference (ISI,Intersymbol Interference) caused by multi-path is reduced. In the ordinary communication environment, the maximum delay spread of the channel (the MDS,Maximum Delay Spread) length is less than the CP time length) can effectively reduce the ISI, communication performance can be guaranteed. However, for extremely complex multi-path environments, such as space capsule, underground tunnel, submarine cabin and other reverberation cavity environment, MDS will be much longer than the conventional CP, so that the transmitted signal waveforms overlap and affect each other. If the length of CP is constant, the ability of ISI suppression will fail and the performance of the system will deteriorate significantly. If the time length of CP is increased, the spectrum resource efficiency of OFDM communication will be greatly reduced, and its performance will also be degraded. In this paper, based on the temporal and spatial focusing mechanism of time inversion (TR,Time Reversal), the method of super long delay spread (ULDS,Ultra-long Delay Spread) suppression in OFDM communication systems is studied. In this paper, the ULDS channel and effective equalization methods are studied. The main work of this paper is as follows: firstly, the suppression methods of inter-symbol interference caused by multi-path in OFDM communication are investigated and analyzed, and the necessity of this paper is explained. This paper introduces the wide application field of TR. The space-time focusing characteristics of tr technology and the ability to suppress channel delay spread make it important to study the performance of OFDM system in ULDS channel. Secondly, the multi-input multiple-output (MIMO,Multi-input Multiple Output) channel correlation and the communication performance of the combination of TR and MIMO technology in complex environment are studied. In addition, the ratio of main lobe to maximum sidelobe in ULDS channel (MSR,Main to Maximum Side-lobe Ratio),) is studied. The communication performance of TR-OFDM in ULDS channel is analyzed. It is concluded that the communication performance is good in the case of specific MSR. The pre-TR and post-TR are simulated in complex communication environment and simple communication environment, and it is concluded that the pre-TR is slightly better than the post-TR in ULDS channel. Finally, the sequential interference cancellation (OSIC,Ordered Successive Interference Cancellation) method is analyzed theoretically. On this basis, this paper proposes a combination of TR and OSIC detection method, and compares the performance of different sort detection. In addition, an equilibrium technique combining TR with least squares (RLS,Recursive Least Squares) is proposed in this paper. Through Matlab simulation analysis, it is concluded that TR-RLS equilibrium technology plays a certain role in ULDS suppression. The work content of this paper is summarized, and the direction of the next research is pointed out.
【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】：2017
【分類(lèi)號(hào)】：TN929.53

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

1 陳少平,姚天任;循環(huán)保護(hù)前綴不足的OFDM通信系統(tǒng)的頻域均衡[J];計(jì)算機(jī)工程與應(yīng)用;2003年18期

2 李森,李思敏,姜興;OFDM中符號(hào)串?dāng)_和子載波串?dāng)_的分析和均衡[J];桂林電子工業(yè)學(xué)院學(xué)報(bào);2003年01期

相關(guān)碩士學(xué)位論文 前3條

1 劉海勇;低復(fù)雜度TR+MIMO無(wú)線通信系統(tǒng)結(jié)構(gòu)與方案研究[D];電子科技大學(xué);2016年

2 陳志新;密集多通道時(shí)間反演無(wú)線通信關(guān)鍵技術(shù)研究[D];電子科技大學(xué);2016年

3 王煥萍;OFDM系統(tǒng)中符號(hào)間干擾抑制方法研究[D];西南交通大學(xué);2009年

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本文編號(hào)：2503946