【摘要】：自由空間光通信(Free-space optical communications,FSO)是一種通過(guò)調(diào)制大氣中傳播的激光來(lái)發(fā)送信息的技術(shù),其傳輸速度可以高達(dá)幾G bps。然而依賴(lài)于天氣的信道損失和湍流衰落是限制FSO鏈路距離的兩個(gè)主要因素。一種解決方案是使用中繼。通過(guò)引入中繼,我們可以將長(zhǎng)鏈路分解成多個(gè)短鏈路,進(jìn)而減少湍流衰落,提升總的鏈路距離。因此,最優(yōu)中繼節(jié)點(diǎn)布設(shè)成為解決問(wèn)題的關(guān)鍵。本文對(duì)FSO中繼節(jié)點(diǎn)布設(shè)進(jìn)行了深入的研究,主要包括以下幾個(gè)方面:(1)給出了多跳FSO廣播系統(tǒng)的模型,并提出了在非限制條件下的最優(yōu)中繼節(jié)點(diǎn)布設(shè)算法。在使多跳FSO廣播通信的中斷概率最小的布設(shè)準(zhǔn)則下,將中繼布設(shè)問(wèn)題轉(zhuǎn)化為無(wú)限制條件下的最優(yōu)化問(wèn)題。把中繼節(jié)點(diǎn)位置作為變量,用戶(hù)節(jié)點(diǎn)的中斷概率作為目標(biāo)函數(shù),建立多目標(biāo)最優(yōu)化模型。然后把用戶(hù)節(jié)點(diǎn)通信服務(wù)優(yōu)先級(jí)作為權(quán)重因子,使用線(xiàn)性加權(quán)和方法把多目標(biāo)最優(yōu)化問(wèn)題轉(zhuǎn)化為單目標(biāo)最優(yōu)化問(wèn)題進(jìn)行求解。(2)提出了在沒(méi)有障礙物和可行域約束條件下,適用于Lognormal和Gamma-Gamma信道模型的兩個(gè)最優(yōu)中繼布設(shè)定理。并理論證明了在發(fā)送功率足夠大的情況下,最優(yōu)中繼節(jié)點(diǎn)應(yīng)該等距離分布在從信源到信宿的所在的直線(xiàn)上。中繼節(jié)點(diǎn)的用戶(hù)數(shù)和中繼節(jié)點(diǎn)的權(quán)重對(duì)最優(yōu)中繼位置沒(méi)有任何影響。同時(shí)給出了仿真過(guò)程,驗(yàn)證了定理的正確性。(3)研究了在障礙物和可行域約束函數(shù)條件下,多跳FSO廣播系統(tǒng)的中繼位置布設(shè)算法。在用圓形、橢圓形、線(xiàn)性描述障礙物約束函數(shù),圓形、橢圓形和多邊形描述可行域約束函數(shù)的基礎(chǔ)上,將布設(shè)問(wèn)題轉(zhuǎn)變?yōu)橄拗菩詶l件下的多目標(biāo)最優(yōu)化問(wèn)題。給出了Lognormal信道模型下的最優(yōu)中繼仿真結(jié)果,并給出實(shí)際工程建議。
[Abstract]:Free-space optical communications (FSO) is a technology to transmit information by modulation of the laser transmitted in the atmosphere. The transmission speed can be as high as a few G bps.. However, the channel loss and turbulent fading of the weather are the two main factors to limit the distance of the FSO link. One solution is to use the relay. By introducing the relay, we can decompose the long link into multiple short links, and then reduce the turbulence fading and increase the total link distance. Therefore, the optimal relay node is the key to solve the problem. This paper makes an in-depth study on the layout of FSO relay nodes, mainly including the following aspects: (1) the multi hop FSO broadcasting system is given. The optimal relay node layout algorithm under non restrictive conditions is proposed. The relay placement problem is transformed into an optimization problem under the unrestricted condition. The relay node position is taken as a variable and the interruption probability of the user node is used as a target function. The target optimization model is used as a weighting factor, and the multiobjective optimization problem is transformed into a single objective optimization problem by linear weighting and method. (2) the two most suitable for Lognormal and Gamma-Gamma channel models under the constraints of no obstacles and feasible domains are proposed. It is proved that the optimal relay node should be equal distance distributed on the line where the source is from the source to the host. The number of the relay nodes and the weight of the relay node have no effect on the optimal relay position. The simulation process is given to verify the correctness of the theorem. (3) (3) the relay location algorithm of multi hop broadcasting system is studied under the condition of obstacle and feasible domain constraint function. On the basis of using circular, elliptical, linear description obstacle constraint function, circular, ellipse and polygon to describe the feasible domain constraint function, the layout problem is transformed into a multi-objective optimization under the restrictive condition. The optimal relay simulation results under the Lognormal channel model are given, and practical engineering proposals are given.
【學(xué)位授予單位】：南京郵電大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TN929.1

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本文編號(hào)：2154671