【作者】 何健；

【导师】 胡艳军；

【作者基本信息】 安徽大学 ， 通信与信息系统， 2007， 硕士

【摘要】 近年来随着无线通信宽带化的发展，同时办公室自动化、家庭电器化和大容量快速通信的迫切需要，室内无线光通信开始得到了极大的关注。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。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，以及人员流动，大大降低了系统的通信质量，甚至有可能造成通信链路的中断。因此，研究链路改进技术对改善室内无线光通信系统的性能具有十分重要的意义。2002年A．H．Khanshan提出了在室内无线光通信中光信号传播存在一条最佳路径，能够降低系统的功率损耗，提高系统的传输性能。本文在此基础之上，针对如何选择最优路径进行了研究和分析。本文重点对最优路径的选择方法进行了深入研究，提出了一种自动选择最优路径的方案。该方案应用了码分多址的思想，根据接收器相关值选择最佳发射器波束。给出了系统的链路结构和传输模型，以及波束选择方案的具体工作过程。主要研究分析了在理想信道和考虑背景光噪声的多径信道两种情况下，发射端采用波束自动选择后，散射点形成的不同图案图形对整个系统性能的影响，用MATLAB进行了仿真，并与准漫射系统性能做了比较。背景光噪声干扰是影响系统性能的一个主要的因素。在考虑了荧光灯产生的散粒噪声情况下，对发端波束自动选择系统方案进一步改进，在接收端采用分集接收技术来消除噪声和抑制多址干扰。并对采用此方案的系统的误码率性能进行了分析和仿真。仿真结果表明其可以有效抑制多址干扰和背景光噪声对系统的影响，进而提高室内无线通信系统的性能。更多还原

【Abstract】 With the modern progress made in wideband wireless communications, office automatic system, and intelligent appliances, the communication system with ever-higher capacity and speed is in great demand, which result in the technology of indoor wireless optical communications become big concern. In wireless communication systems, comparing with traditional radio bands, optical bands has the advantage of high transmission capacity and interference resistance. Due the factors of people mobility, and light signal reflection off walls, the ceiling, tables, the floor, etc, the quality of transition deteriorate highly, even has the possibility to break off the link. Therefore, the study on techniques for link improvement to enhance performance of the wireless optical communication systems is extremely significant. The idea of an optimum path existed in the optical signal transmission for the wireless optical communication which was proposed by A. H. Khanshan in 2002, Arguing that it can reduce the system power loss and improve the performance. This thesis investigates how to select the optimum path based on this foundation.Our focus is on the schemes for selecting an optimal path, of which a realization is herein presented. This scheme self-selects the transmitter beam according to the receiver’s correlation value. We analyze the performance improvement from our system with beam auto-selection over a quasi-diffuse system, under either an ideal channel or a multipath channel with background noise, simulated by using MATLAB program.The background light noise is a primary factor that affecting the system performance. We further analyze the performance of a beam auto-selection system with diversity receiving techniques, in the presence of shot noise from fluorescent illumination. Simulation results verify that its superior mitigation of the background noise.更多还原