本文關(guān)鍵詞： 室外可見光通信 最大似然檢測 星座設(shè)計(jì)　出處：《鄭州大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著無線通信技術(shù)的快速發(fā)展,無線頻譜資源短缺的問題日益明顯。作為一種新興的無線通信技術(shù),可見光通信(Visible Light Communication)的出現(xiàn)在一定程度上緩解了無線電頻譜緊張的情況,其兼具環(huán)保安全、架設(shè)簡單、無需無線電頻譜認(rèn)證等優(yōu)點(diǎn),可應(yīng)用于智能交通、智能照明和室內(nèi)定位等眾多領(lǐng)域。近年來,可見光通信技術(shù)得到了廣泛的關(guān)注與研究,成為未來無線通信技術(shù)中的重要部分。然而,由于光信號(hào)的非負(fù)特性,現(xiàn)有射頻通信系統(tǒng)中已經(jīng)趨于成熟的技術(shù)很難直接應(yīng)用于可見光通信。目前,可見光通信的研究方向大多集中于室內(nèi)場景下,對于室外場景研究較少。室外可見光通信主要受到大氣信道湍流和衰減的影響,導(dǎo)致光強(qiáng)度信號(hào)隨機(jī)變化,且信道沒有統(tǒng)一定論的數(shù)學(xué)模型,這些問題嚴(yán)重影響了室外場景下可見光通信的性能。鑒于此,本文主要研究了室外可見光通信系統(tǒng)的調(diào)制與檢測算法。本文首先分析了室外可見光通信信道的特點(diǎn),概述了典型的信道模型,研究了系統(tǒng)最終統(tǒng)計(jì)判決量的概率密度分布,針對信道復(fù)雜多變、影響因素眾多的問題,在大規(guī)模MIMO可見光通信系統(tǒng)的場景下,提出了已知信道模型統(tǒng)計(jì)特性的條件下,一種對現(xiàn)有均值檢測算法進(jìn)行改進(jìn)的方法和一種將最大似然準(zhǔn)則應(yīng)用在可見光通信中單極性多階脈沖幅度調(diào)制(PAM)信號(hào)進(jìn)行半盲檢測的算法。仿真結(jié)果表明,本文所述算法與傳統(tǒng)均值檢測算法相比準(zhǔn)確性更高,可提升系統(tǒng)誤差性能。其次,在對最大似然檢測算法研究的基礎(chǔ)上,進(jìn)一步推導(dǎo)了系統(tǒng)平均星座錯(cuò)誤概率的表達(dá)式,將現(xiàn)有單極性PAM調(diào)制中使用的等間隔星座進(jìn)行了優(yōu)化,提出了一種非等間隔的聯(lián)合調(diào)制星座優(yōu)化方案,以適應(yīng)室外可見光通信信道的特點(diǎn)。最后,針對本文中非確定性多項(xiàng)式的優(yōu)化問題的次優(yōu)解,提出了一種數(shù)值求解的方法。仿真結(jié)果表明,采用優(yōu)化后的調(diào)制星座可進(jìn)一步降低系統(tǒng)平均星座錯(cuò)誤概率,尤其在信噪比較高或收發(fā)兩端天線數(shù)量較多的情況下采用本文中所提出的方法系統(tǒng)性能優(yōu)勢更為明顯。
[Abstract]:With the rapid development of wireless communication technology, the shortage of wireless spectrum resources is becoming more and more obvious. Visible Light Communication (Visible Light Communication) has alleviated the radio spectrum tension to a certain extent, and it is environmentally safe and easy to set up. It can be used in many fields such as intelligent transportation, intelligent lighting and indoor positioning without radio spectrum authentication. In recent years, visible light communication technology has received extensive attention and research. It has become an important part of wireless communication technology in the future. However, due to the non-negative characteristics of optical signal, it is difficult to apply the mature technology in the existing radio frequency communication system directly to visible light communication. The research direction of visible light communication is mostly focused on indoor scenes, but little on outdoor scenes. Outdoor visible light communication is mainly affected by atmospheric channel turbulence and attenuation, resulting in random changes of optical intensity signal. And there is no unified mathematical model of the channel. These problems seriously affect the performance of visible light communication in outdoor scenes. This paper mainly studies the modulation and detection algorithms of outdoor visible light communication system. Firstly, this paper analyzes the characteristics of outdoor visible light communication channel and summarizes the typical channel model. This paper studies the probability density distribution of the final statistical decision quantity of the system. Aiming at the complex and changeable channel and numerous factors, the system is in the scene of large-scale MIMO visible light communication system. The statistical properties of the channel model are given. A method to improve the existing mean value Detection algorithm and a method to apply the maximum likelihood Criterion to unipolar Multi-order Pulse amplitude Modulation (PAM) in visible Light Communication. The algorithm of semi-blind signal detection. The simulation results show that. Compared with the traditional mean detection algorithm, the proposed algorithm is more accurate and can improve the error performance of the system. Secondly, based on the research of the maximum likelihood detection algorithm. Furthermore, the expression of the error probability of the system average constellation is derived, the equal-interval constellation used in the existing unipolar PAM modulation is optimized, and a non-equal-interval joint modulation constellation optimization scheme is proposed. In order to adapt to the characteristics of outdoor visible light communication channel. Finally, a numerical method is proposed to solve the non-deterministic polynomial optimization problem. The simulation results show that. Using the optimized modulation constellation can further reduce the error probability of the system average constellation. Especially when the signal-to-noise ratio (SNR) is high or the number of antennas at both ends of the transceiver is large, the system performance advantage of the proposed method is more obvious.
【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TN919.3;TN929.1

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本文編號(hào)：1459269