【作者】 潘继敏；

【导师】 吴长奇；

【作者基本信息】 燕山大学 ， 电路与系统， 2004， 硕士

【摘要】 由于光载波传输容量的巨大潜力，使得光纤传输系统成为干线传输网络的首选。但是在近距离的无线接入、临时的中继传输线路以及移动的通信环境下，无线通信系统仍是不可缺少的。在无线通信系统中，光频段与微波以下的射频频段相比，具有传输容量大、不易受到干扰等特殊的优点。因此，近年来随着计算机网络宽带化的发展，无线光通信系统重新又受到人们的重视。在此背景下，本文着重研究了光无线通信系统中的信号处理技术。本文重点对大气无线光通信及室内无线光通信进行了研究。大气无线光通信是以大气作为传输媒介，主要应用在相邻两建筑物间进行点对点的通信。由于在这里是以光作为载波，波长较短，这样信号受大气中各种粒子的影响较大。本文分析了大气信道情况，并且给出了在大气湍流中光场强度的分布情况。本文的工作主要是针对大气湍流的影响进行分析，并且提出了两种通过分集来提高系统性能的解决方法，并利用MATLAB进行了数值仿真。由于在进行点对点通信中要求收发器间严格的对准，风压、热扩散和轻微的地震等都将引起建筑物的摆动，由此产生对准偏差，这里结合湍流的影响分析了其对通信过程中误码率的影响。室内无线光通信主要用在同一房间内各种仪器设备间的通信，或是建造室内光无线局域网。由于室内环境中各种物体如墙壁、天花板、桌子、地面等对光束的反射，使得信道很复杂，这里主要分析了直射链路和散射链路两种信道条件。直射链路路径损耗小，但是覆盖范围小；散射链路的路径损耗大，但是覆盖范围大。要想达到房间内的无缝覆盖就必须采用散射链路。对于散射链路可以采用角度分集技术来提高接收端的视场角，再与脉冲位置调制相结合，提出了一种改进的系统模型。更多还原

【Abstract】 The transmission capacity of optical carrier is huge，SO fiber optical transmission systems become the first selection of trunk transmission network．But wireless transmission system is indispensable for wireless accessing，temporary trunk line and mobile communications．Light wave compares with radio frequency．It has the virtues that transmission capacity is huge and it is difficultly disturbed．With computer Wide Band developing，we pay attentionto wireless optical communication again．The paper mainly researches signal processing technology about wireless optical communication．The emphasis of the paper is atmospheric optical wireless communication and indoor optical wireless communication．The system uses atmosphere as a propagation medium。It is mostly used point to point communication between two buildings．Bandwidth is short because carrier wave is light．So the signal is affected by the all kinds of particles in the atmosphere．In the paper we discussed the atmospheric channel，and give the marginal distribution of light intensity fading induced by turbulence．My work is analysis the effect of atmospheric turbulence，proposed the solution by diversity technology to improve performance of system and simulate by MATLAB．Dynamic wind loads，thermal expansion，and weak earthquakes cause buildings to sway．These sways distort the alignment between transmitter and receiver．A bit．error ratio model is developed that takes into account both building sway and atmospheric turbulence． We can make all equipments in 1ab to communication or build an indoor optical wireless LAN．The channel is complex，because the light is reflected by the wall，the ceiling，the table，the floor and SO on．The paper analyzes line of sight(LOS)and non—directed diffuse link．Power efficiency of diffusive propagation system is quite lower than that of LO S propagation system，but the optical carrier iS reflected diffusively to omni direction and fills the wholeroom．So we must adopt diffusive link to no leak cover．We analyze angle diversity technology to improve receiver’S FOV,and combining pulse position <WP=6>modulation(PPM)，propose a improved model of system更多还原