本文選題：電磁波 + 軌道角動(dòng)量��； 參考：《浙江大學(xué)》2017年碩士論文

【摘要】：近年來因波前為渦旋形狀而具備軌道角動(dòng)量(OAM)的電磁波所展現(xiàn)的信息攜帶能力越來越受關(guān)注。作為電磁場(chǎng)的基本物理量,OAM在物理層提供了信息調(diào)制的額外自由度,利用不同OAM模態(tài)之間的正交特性來承載信息有望提升系統(tǒng)的頻譜效率。鑒于OAM電波固有的傳輸特性,如何將其利用于無線傳輸并對(duì)可能帶來的實(shí)際增益進(jìn)行分析意義重大。本文圍繞OAM在無線傳輸領(lǐng)域的應(yīng)用展開研究,根據(jù)不同的場(chǎng)景進(jìn)行系統(tǒng)建模和性能分析,主要內(nèi)容概述如下:本文建立和分析了基于均勻環(huán)形陣列(UCA)的OAM復(fù)用傳輸模型。UCA作為一種能靈活輻射和接收OAM電波的方式,在OAM復(fù)用傳輸方面發(fā)揮著重要作用,而相同的配置也可基于傳統(tǒng)的MIMO方式傳輸,我們期望分析這兩種傳輸方式的差異和性能關(guān)系,進(jìn)而揭示在在不同陣列配置和發(fā)送端信道邊信息(CSI)假設(shè)下各自的優(yōu)勢(shì)和不足。模型中發(fā)送端單個(gè)UCA通過饋電疊加同時(shí)輻射多路渦旋電波,通過對(duì)UCA的接收信號(hào)進(jìn)行DFT變換或基于MMSE準(zhǔn)則來檢測(cè)信號(hào)。以傳輸速率為參考,結(jié)果表明在發(fā)端已知CSI時(shí)如果兩個(gè)平行的UCA有相同的陣元個(gè)數(shù)則兩種傳輸方式等效,OAM的優(yōu)勢(shì)體現(xiàn)在發(fā)端未知CSI且收發(fā)陣列對(duì)齊時(shí),DFT檢測(cè)方式達(dá)到信道本身提供的最大傳輸速率�？紤]到不同模式值的OAM電波具備的內(nèi)在正交特性,本文的第二部分,我們希望將其正交性利用在自干擾消除方面并建立了基于OAM的同時(shí)同頻全雙工傳輸模型。模型中利用不同模式的OAM電波分別作為收發(fā)信號(hào)的載波,收發(fā)天線放置于同一個(gè)參考軸但彼此之間存在傾角。由于饋電偏差等因素導(dǎo)致輻射的OAM波束含有寄生分量,和接收模式一致的OAM分量將會(huì)被本地節(jié)點(diǎn)接收并作為殘留干擾而存在。以最大化雙工系統(tǒng)和速率為度量,在不同的模式純度和白噪聲強(qiáng)度下分析了最佳的雙工模式選擇。結(jié)果表明,在殘留干擾起主導(dǎo)作用時(shí)雙工模式選擇為可選模式集中的最大或最小值;在干擾和噪聲同時(shí)起作用時(shí),模式選擇在干擾和噪聲單獨(dú)存在時(shí)的極端值間過度變化。本文最后研究了OAM和MIMO相融合的傳輸系統(tǒng)。OAM和MIMO結(jié)合相當(dāng)于拓展了原有的MIMO傳輸維度,在每個(gè)MIMO支路復(fù)用多路OAM有望進(jìn)一步提升系統(tǒng)頻譜效率。與此同時(shí),OAM波束的發(fā)散效果相比平面波更加嚴(yán)重,導(dǎo)致接收功率快速衰減,基于此,我們建立了通用的復(fù)用傳輸模型以分析在這兩個(gè)矛盾因素的影響下融合傳輸可能帶來的增益。結(jié)果表明,在接收天線能覆蓋波束有效拓展半徑的前提下,近距離時(shí)復(fù)用傳輸?shù)木S度越多傳輸?shù)娜萘恳苍酱?而由于功率衰減在遠(yuǎn)距離時(shí)OAM-MIMO的傳輸速率不如MIMO。
[Abstract]:In recent years, more and more attention has been paid to the information carrying ability of electromagnetic waves with orbital angular momentum (OAM) due to the vortex-shaped wavefront. As the basic physical quantity of electromagnetic field, OAM provides additional degree of freedom for information modulation in physical layer. It is expected to improve the spectral efficiency of the system by using the orthogonal characteristic of different OAM modes to carry information. In view of the inherent transmission characteristics of OAM waves, it is of great significance to apply them to wireless transmission and to analyze the possible actual gain. In this paper, the application of OAM in wireless transmission is studied, and the system modeling and performance analysis are carried out according to different scenarios. The main contents are summarized as follows: in this paper, OAM multiplexing transmission model based on uniform ring array (UCA) is established and analyzed. UCA plays an important role in OAM multiplexing transmission as a flexible way to radiate and receive OAM radio waves. The same configuration can also be based on the traditional MIMO transmission. We expect to analyze the differences and performance relationships between the two transmission modes, and then reveal their respective advantages and disadvantages under different array configurations and channel side information (CSI) assumptions. In the model, a single UCA at the transmitter simultaneously radiates multi-channel vortex waves through the feed superposition, and detects the signal by DFT transform or based on MMSE criterion. Taking the transmission rate as a reference, The results show that if two parallel UCA have the same number of elements when the CSI is known at the source, the advantage of the two transmission modes is that the CSI is unknown and the receiver array is aligned to achieve the maximum transmission rate provided by the channel itself. Considering the inherent orthogonality of OAM waves with different mode values, in the second part of this paper, we hope to use the orthogonality in self-interference cancellation and establish a full-duplex transmission model based on OAM. In the model, OAM waves of different modes are used as carriers of the transceiver signal, and the antenna is placed in the same reference axis, but there are obliquity between them. Due to the error of the feed, the OAM beam contained parasitic component, and the OAM component which is consistent with the receiving mode will be received by the local node and will exist as a residual interference. Based on the maximization of duplex system and rate, the optimal duplex mode selection is analyzed under different mode purity and white noise intensity. The results show that the duplex mode is the maximum or minimum value in the optional mode set when residual interference is dominant, and the extreme value between interference and noise is excessive when the interference and noise are acting simultaneously. Finally, this paper studies the OAM and MIMO transmission system. The combination of OAM and MIMO is equivalent to extending the original MIMO transmission dimension, and multiplexing multiple OAM in each MIMO branch is expected to further improve the spectral efficiency of the system. At the same time, the divergence effect of OAM beam is more serious than that of plane wave, which leads to the fast attenuation of receiving power. A universal multiplexing transmission model is established to analyze the possible gains from the fusion transmission under the influence of these two contradictory factors. The results show that under the condition that the receiving antenna can effectively extend the radius of the beam, the larger the transmission capacity of the dimension of close-range multiplexing transmission is, the lower the transmission rate of OAM-MIMO is when the power attenuates at a long distance.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TN92
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本文編號(hào)：2078992