【摘要】：無線光通信即自由空間光(Free-Space Optical, FSO)通信,因其具有高帶寬、抗干擾、高數(shù)據(jù)傳輸率等特點,越來越受到國內(nèi)外的重視,是無線通信領(lǐng)域研究的重要方向之一。FSO雖然有很多優(yōu)點,但也存在諸多影響FSO通信性能的因素,比如大氣湍流,背景噪聲,熱噪聲等,因此本文首先闡述了FSO通信的原理和關(guān)鍵技術(shù),針對自由空間光通信系統(tǒng)中光子計數(shù)技術(shù),研究通信過程中各類噪聲、干擾的影響,綜合考慮熱輻射、背景輻射及大氣湍流的影響并進(jìn)行系統(tǒng)建模,推導(dǎo)了基于Laguerre模型采用開關(guān)鍵控(On-Off Keying, OOK)調(diào)制以及脈沖位置調(diào)制(Pulse Position Modulation, PPM)時在不同大氣湍流模型下的誤碼率(Bit Error Rate, BER)計算方式,并通過計算機(jī)蒙特卡洛仿真驗證了所提出算法的正確性,通過仿真結(jié)果表明大氣湍流和噪聲是影響自由空間光通信性能的主要因素。之后本文提出通過空間分集技術(shù)來調(diào)高系統(tǒng)性能,并分別推導(dǎo)了基于Laguerre模型采用發(fā)射分集、接收分集以及多輸入多輸出技術(shù)(Multiple-Input Multiple-Output, MIMO)系統(tǒng)在強(qiáng)大氣湍流下的誤碼率表達(dá)式,通過仿真評估了空間分集對系統(tǒng)性能的改進(jìn)效果。此外,本文還研究了基于Laguerre模型的交織分多址(Interleave-Di vision Multiple-Access, IDMA)多用戶系統(tǒng)的迭代檢測技術(shù),提出基于最優(yōu)貝葉斯(Optimum Bayesian, OB)算法的多用戶檢測(Multiuser Detection, MUD)方案。通過計算機(jī)仿真,測試系統(tǒng)在不同環(huán)境下的性能,仿真結(jié)果表明IDMA技術(shù)可以有效削弱多用戶干擾(Multiple Access Interference, MAI),而OB算法可加快系統(tǒng)檢測收斂速度,提升系統(tǒng)性能。
[Abstract]:Wireless optical communication, known as free space optical (Free-Space Optical, FSO) communication, has attracted more and more attention at home and abroad because of its high bandwidth, anti-jamming and high data transmission rate, although it has many advantages in the field of wireless communication. However, there are many factors that affect the performance of FSO communication, such as atmospheric turbulence, background noise, thermal noise and so on. Therefore, the principle and key technology of FSO communication are first expounded in this paper, aiming at photon counting technology in free space optical communication system. The effects of various kinds of noise and interference in the communication process are studied. The effects of thermal radiation, background radiation and atmospheric turbulence are considered and the system model is established. Based on the Laguerre model, the (Bit Error Rate, BER) calculation method of bit error rate (BER) under different atmospheric turbulence models using open key control (On-Off Keying, OOK) modulation and pulse position modulation (Pulse Position Modulation, PPM) is derived. The correctness of the proposed algorithm is verified by computer Monte Carlo simulation. The simulation results show that atmospheric turbulence and noise are the main factors affecting the performance of optical communication in free space. After that, this paper proposes to improve the performance of the system by spatial diversity, and derives the BER expressions based on Laguerre model using transmit diversity, receiving diversity and multiple input and multiple output (Multiple-Input Multiple-Output, MIMO) systems under strong gas turbulence. The improvement effect of spatial diversity on system performance is evaluated by simulation. In addition, this paper also studies the iterative detection technology of interleaved division multiple access (Interleave-Di vision Multiple-Access, IDMA) multiuser systems based on Laguerre model, and proposes a multiuser detection (Multiuser Detection, MUD) scheme based on the optimal Bayesian (Optimum Bayesian, OB) algorithm. Through computer simulation, the performance of the system in different environments is tested. The simulation results show that the IDMA technology can effectively weaken the multi-user interference (Multiple Access Interference, MAI), while the OB algorithm can accelerate the convergence speed of the system detection and improve the system performance.
【學(xué)位授予單位】：復(fù)旦大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN929.1

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本文編號：2234031