本文關鍵詞： 軌道角動量 傳輸特性 建模 大氣湍流　出處：《寧夏大學》2017年碩士論文　論文類型：學位論文

【摘要】：隨著通信技術的日益發(fā)展,當今無線通信系統(tǒng)正向著更高速率和更高帶寬的目標邁進。容量需求和頻譜資源短缺的矛盾在這個智能終端以及互聯(lián)網(wǎng)飛速發(fā)展的時代顯得尤為突出,因此,解決這一問題成為5G無線通信技術中迫在眉睫的事情。軌道角動量(orbital angular momentum,OAM)技術能夠在不增加帶寬的條件下,極大地提高系統(tǒng)容量,這就讓它在無線通信領域里的研究以及應用日漸成為一個熱點。目前把軌道角動量技術應用到無線通信系統(tǒng)中只是探索階段,還有很多技術難關需要攻克。本課題以軌道角動量的基本性質為理論基礎,提出無線通信中軌道角動量的模型,并且對電磁渦旋波的傳輸特性進行研究和分析。在傳播過程中,電磁渦旋波會受到大氣湍流等因素的影響,使相位的扭轉角度發(fā)生改變,從而破壞電磁渦旋波最初的波形。本課題為容量需求和頻譜資源短缺的問題提供一定的理論支持,從而加快智能終端的普及和互聯(lián)網(wǎng)的發(fā)展。本文主要工作內(nèi)容如下:(1)文章提出了無線通信系統(tǒng)里軌道角動量的模型,本文將光子軌道角動量的模型應用于低頻,建立類似于拉蓋爾高斯光束的電磁渦旋波模型,并且通過Labview軟件對30GHz的OAM波束進行仿真,這為本文后續(xù)的研究工作打下了基礎。(2)本文通過Labview仿真軟件研究無線通信中電磁渦旋波在理想信道中的傳輸特性。攜帶軌道角動量的電磁渦旋波在理想信道中傳輸后,電場分布發(fā)散,出現(xiàn)波束展寬現(xiàn)象,能量產(chǎn)生損耗;相位發(fā)生隨機畸變,等相位線彎曲。之后研究了距離、波長以及束腰半徑等參數(shù)對軌道角動量傳輸特性的影響,隨著軌道角動量在理想信道中傳輸距離的增大,電磁渦旋波波形變化逐漸嚴重;當傳輸距離為0時,電磁渦旋波的相位分布僅由OAM模態(tài)值的大小和正負決定。(3)本文研究了無線通信系統(tǒng)中大氣湍流對電磁渦旋波傳輸特性產(chǎn)生的影響。傳輸距離相同時,電磁渦旋波在大氣湍流里傳播明顯比在理想信道里傳播波形損失嚴重;電磁渦旋波攜帶的OAM模態(tài)值絕對值越大,它受到大氣湍流的影響就越大;當模態(tài)值大小相同、符號相反時,電磁渦旋波受到大氣湍流的影響基本相同,只因為大氣湍流的隨機性有微小的差異。之后文章研究了不同傳輸距離和大氣湍流強度對軌道角動量產(chǎn)生的影響。最后采用發(fā)射空間分集技術來抑制大氣湍流對軌道角動量傳輸特性的影響,并且發(fā)現(xiàn)不考慮空間、成本等限制時,發(fā)射天線數(shù)量越多,抑制大氣湍流對軌道角動量影響的效果越好。
[Abstract]:With the development of communication technology. Nowadays, the wireless communication system is moving towards the goal of higher rate and higher bandwidth. The contradiction between the capacity demand and the shortage of spectrum resources is particularly prominent in this era of intelligent terminals and the rapid development of the Internet. Solving this problem has become an urgent matter in 5G wireless communication technology. Orbital angular momentum angular momentum. OAM) technology can greatly improve system capacity without increasing bandwidth. This makes its research and application in the field of wireless communication increasingly become a hot spot. At present, the application of orbital angular momentum technology to wireless communication systems is only a phase of exploration. There are still many technical difficulties to overcome. Based on the basic properties of orbital angular momentum, a model of orbital angular momentum in wireless communication is proposed in this paper. And the transmission characteristics of electromagnetic vortex wave are studied and analyzed. In the process of propagation, the electromagnetic vortex wave will be affected by atmospheric turbulence and other factors, making the phase torsional angle change. In order to destroy the initial waveform of electromagnetic vortex wave, this paper provides some theoretical support for the problem of capacity demand and the shortage of spectrum resources. In order to speed up the popularity of intelligent terminals and the development of the Internet. The main work of this paper is as follows: 1) the paper puts forward the model of orbital angular momentum in wireless communication system. In this paper, the photon orbital angular momentum model is applied to the low frequency, and the electromagnetic vortex wave model similar to the Laguerre Gao Si beam is established, and the 30GHz OAM beam is simulated by Labview software. This will lay a foundation for further research work in this paper. In this paper, Labview simulation software is used to study the transmission characteristics of electromagnetic vortex wave in the ideal channel in wireless communication. After the electromagnetic vortex wave with orbital angular momentum is transmitted in the ideal channel. The distribution of electric field diverges and the beam widens and the energy is lost. The influence of the parameters such as distance, wavelength and beam waist radius on the transmission characteristics of orbital angular momentum is studied, with the increase of orbital angular momentum transmission distance in ideal channel. The change of electromagnetic vortex wave waveform is serious. When the transmission distance is 0:00. The phase distribution of electromagnetic vortex wave is determined only by the magnitude of OAM mode value and the positive and negative value.) in this paper, the influence of atmospheric turbulence on electromagnetic vortex wave propagation characteristics in wireless communication system is studied. The electromagnetic vortex wave propagates more seriously in the atmospheric turbulence than in the ideal channel. The larger the absolute value of OAM mode carried by electromagnetic vortex wave is, the greater it will be affected by atmospheric turbulence. When the modal value is the same and the symbol is opposite, the electromagnetic vortex wave is affected by the atmospheric turbulence basically the same. It is only because of the slight difference in the randomness of atmospheric turbulence. Then the influence of different transmission distance and atmospheric turbulence intensity on orbital angular momentum is studied. Finally, emission space diversity technique is used to suppress atmospheric turbulence. The influence of orbital angular momentum transmission characteristics. It is also found that the more the number of transmitting antennas is, the better the effect of suppressing atmospheric turbulence on orbital angular momentum is when space and cost are not taken into account.
【學位授予單位】：寧夏大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN92

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