【作者】 潘俊俊；

【导师】 贾振红；

【作者基本信息】 新疆大学 ， 通信与信息系统， 2007， 硕士

【摘要】 作为一种新型宽带无线通信技术及下一代光通信发展方向之一的无线光通信,结合了微波通信和光纤通信的优势,具有频谱资源丰富、信息容量大,抗电磁干扰、保密性能好、设备轻便尺寸小、成本相对低廉、快速链路部署、组网灵活、网络传输协议透明、扩展性好等优点,可应用于“最后一公里”宽带接入、临时应急通信、城域网扩展、局域网扩容、企业或小区内部网络互连、移动无线基站数据回传、光纤通信链路的备份、短距离军事保密通信、战场移动指挥通信及其它不宜布线、施工难度大、地域环境与成本受限的通信场合。本文就无线大气光通信系统在近地面视距复杂大气信道中实现可靠的全天候通信传输进行了系统参数研究设计及各项性能指标的分析与改进。以激光作为载波直接在大气信道中进行信息传送会受到大气产生的一系列干扰作用的影响,文中就静态均匀稳定大气中大气分子和气溶胶粒子的吸收和散射引起的大气衰减、动态大气湍流对系统接收端造成的光强闪烁效应、光波的自由空间传输损耗、系统光收发端天线效率、背景噪声及接收检测固有噪声等重要传输性能影响因素进行了分析讨论,建立了无线光通信大气信道传输模型,以较准确地预测接收光信号的强度起伏特性的Gamma-Gamma光强闪烁分布来描述大气湍流信道,将数字副载波PSK强度调制与直接检测技术应用于实现数字比特信息传送的无线大气激光通信系统,基于原理设计框图对系统的重要性能参量进行了理论推导与结果仿真,考察系统的差错性能与优越性,并在此基础上采用信道编码技术进行了性能改进。更多还原

【Abstract】 As a kind of new wide-band wireless communication technique and one of the developing directions of the next generation optical communication, wireless optical communication combines the superiorities of microwave and fiber communication. It is rich in frequency resources. It has large information capacity and good performance of resisting electromagnetic interference and keeping secrets. Its equipments have small size and very portable. The cost is relatively low. The link of it can be quickly arranged and it is flexible to make up network. It also has other advantages, such as quickly forming network, transparent network transmitting protocol, well performance of broadening, etc. The wireless optical communication can be used in‘last mile’wide-band accepting, temporary communication for meeting emergency, extending the city area network, expanding the capacity of the local area network, interconnecting the inner-network of the enterprise or small districts, data resending of the wireless mobile base station, backuping the communication link of the fiber lines, short-space military communication in secret way, battlefield mobile commanding communication, some other places where are not fit to lay out or hard to working on the communication links or the region environment is limited.To realize the reliable all-day communication transmitting of the wireless atmospheric laser communication system in near-ground short-space and complicated atmospheric channel, this text studies and designs the system parameters,analyzes and improves the system’s certain performance indexes. To transmit information directly in the atmospheric channel, making laser as the wave-carrier, the light wave is strongly influenced by a series of interfered effects. The text make some factors as the important affecting performance indexes, analyze and discusses these factors then uses them to build the channel model of the wireless atmospheric laser communication. These factors contains the atmospheric attenuation caused by absorption and scattering that made by atmospheric molecule and aerosol particles in stable and static state atmosphere, the intensity scintillation at the receiving port caused by atmospheric turbulence in unstable and dynamic state atmosphere, the free-space optical loss, the efficiency of the optical sending and receiving ports’antennas, the background noise and the noises of the received system. Gamma-Gamma scintillation distribution is used to model the atmospheric turbulence channel, which well matches and predicts the characteristics of the received intensity fluctuation. Subcarrier PSK intensity modulation/direct-detection technique is used to realize the digital bits transmitting. Based on the block diagram of the system, the important error performance parameters are deduced theoretically and simulated. The error performance and the preferable properties of the system are discussed. The ways to improve the performance like different sorts of coding are analyzed and simulated.更多还原