陆地自由空间光通信系统性能分析

发布时间：2018-05-10 06:05

本文选题：自由空间光通信 + 性能分析　；参考：《吉林大学》2017年博士论文

【摘要】：自由空间光通信(FSOC,free space optics communication)是指利用红外至紫外波段的光载波,在无波导传输媒介中传输信息的技术。FSOC系统具有通信速率高、保密性好、非授权频谱、安装灵活、成本低廉等优点,广泛应用在城域网扩展、灾后应急通信、光纤备份、蜂窝回程网络、量子通信以及军事保密通信等领域。随着物联网和大数据时代的来临,人们对高速、大容量通信网络的需求不断提升,陆地FSOC系统在“最后一英里”问题中的应用逐渐成为研究热点。然而,光束在传播路径上遇到的大气湍流以及发射机接收机之间的对准误差会导致光信号在幅度和相位上发生闪烁和畸变,进而大幅降低FSOC系统的通信性能,而FSOC系统点对点传输的特性则会降低系统的使用效率。为了解决FSOC系统的技术瓶颈,分集技术可以改善FSOC系统的通信质量,减缓大气湍流衰落和对准误差对通信性能的影响;复用技术可以提高FSOC系统的使用效率,在不增加设备成本的情况下,为更多的用户提供服务;混合射频/自由空间光通信中继技术兼顾改善通信性能和扩展通信范围,将FSOC技术与传统射频(RF,radio frequency)通信技术相融合,发挥各自优势,提高通信网络整体性能。在设计和部署基于上述技术的FSOC系统时,需要综合考虑系统的成本、复杂度以及通信性能等因素。因此,非常有必要对分集、复用以及中继FSOC系统的通信性能进行定量的分析,以确保FSOC系统在可控预算内提供最优的通信服务。本文首先分析采用并行发射分集技术的FSOC系统渐进性能。随后,分析基于探测器复用的同步FSOC系统性能。进而,研究混合RF/FSOC中继系统的端到端通信性能。最后,计算基于非精确信道模型的FSOC系统的通信性能指标。本文的主要研究工作集中于以下几个方面:首先,阐述本课题研究的意义和背景,介绍基于分集、复用以及混合RF/FSOC中继技术的FSOC系统性能分析的研究现状,详细介绍FSOC系统中的大气湍流信道模型和对准误差模型。其次,研究了并行发射分集技术在FSOC系统中的应用,分析了采用发射分集技术的FSOC系统的渐进性能。针对传统发射选择分集(TLS,transmit laser selection)技术会造成发射机频繁切换的问题,引入了切换轮询发射(SET,switch-and-examine transmit)技术以及后选择切换轮询发射技术(SETps,switch-and-examine transmit with post-selection)。针对TLS系统发射功率受到安全标准限制的问题,提出了改进的双分支发射选择(Dual-TLS,dual-branch transmit laser selection)原理以及分组发射选择(Group-TLS,group transmit laser selection)原理。基于大气湍流和对准误差复合渐进信道模型,推导了基于上述四种发射分集技术的FSOC系统的渐进平均符号错误概率和分集增益表达式。再次,在两用户同步FSOC通信场景下,研究基于探测器复用的FSOC系统的性能。两个FSOC用户分别定义为主用户和次用户,二者以不同的功率同步发送数据。针对无背景辐射噪声且接收机已知信道状态信息的情况,分别推导主用户和次用户在信道状态信息下的条件符号错误概率,并利用大气湍流和对准误差信道模型,计算平均符号错误概率。针对有背景辐射噪声的情况,推导主用户和次用户数据的判决准则,并计算在信道状态信息下的条件符号错误概率。随后,分析基于中继的混合RF/FSOC系统的端到端性能。系统中的射频用户采用空时编码技术,中继节点分别采用固定增益放大转发模式和可变增益放大转发模式,RF链路服从瑞利衰落,FSOC链路受大气湍流和对准误差的影响。我们推导系统端到端瞬时信噪比的累积分布函数,并基于此分别计算系统的中断概率与平均符号错误概率。此外,利用Meijer-G函数在零点的级数展开性质,讨论了固定增益中继混合RF/FSOC系统的渐进性能。最后,分析基于非精确湍流信道模型的FSOC系统性能。假设非精确模型为精确信道增益与高斯随机变量的叠加,而精确信道增益服从考虑对准误差的Gamma-Gamma湍流衰落。我们首先计算非精确信道增益的统计特征,并以此推导了非精确信道增益FSOC系统的中断概率、平均符号错误概率以及遍历容量等性能指标的表达式。
[Abstract]:FSOC (free space optics communication) refers to the technology that uses the optical carrier of the infrared to the ultraviolet band to transmit information in the media without waveguide transmission. The.FSOC system has the advantages of high communication rate, good secrecy, unauthorized spectrum, flexible installation and low cost and so on. It is widely used in the expansion of the metropolitan area network and the emergency communication after the disaster. In the fields of optical fiber backup, cellular return network, quantum communication and military secure communications. With the advent of the Internet of things and the era of big data, the demand for high-speed and large capacity communication networks is increasing. The application of land FSOC system in the "last mile" problem is gradually becoming a hot spot. However, the beam is encountered on the path of propagation. The atmospheric turbulence and the alignment error between the transmitter receiver will cause the light signal to scintillation and distortion in the amplitude and phase, and thus greatly reduce the communication performance of the FSOC system, and the point to point transmission of the FSOC system will reduce the use efficiency of the system. In order to solve the technical bottleneck of the FSOC system, the diversity technology can be changed. The communication quality of good FSOC system reduces the influence of atmospheric turbulence fading and alignment error on communication performance; reuse technology can improve the use efficiency of FSOC systems and provide services for more users without increasing the cost of equipment; hybrid radio frequency / free space optical communication relay technology improves communication performance and extended communication model. It combines the FSOC technology with the traditional RF (radio frequency) communication technology to improve the overall performance of the communication network. When designing and deploying the FSOC system based on the above technology, it is necessary to consider the cost, complexity and communication performance of the system. Therefore, it is very necessary to divide, reuse and relay F. The communication performance of the SOC system is quantitatively analyzed in order to ensure that the FSOC system provides the optimal communication service in the controllable budget. This paper first analyzes the progressive performance of the FSOC system using parallel transmit diversity technology. Then, the performance of the synchronous FSOC system based on the detector reuse is analyzed. Then, the end to end of the hybrid RF/FSOC relay system is studied. In the end, the main research work of this paper is focused on the following aspects: first, the significance and background of the research are expounded, and the research status of the performance analysis of FSOC system based on diversity, reuse and hybrid RF/FSOC relay technology is introduced, and FSO is introduced in detail. The atmospheric turbulence channel model and the alignment error model in the C system. Secondly, the application of the parallel transmit diversity technology in the FSOC system is studied. The gradual performance of the FSOC system using the transmit diversity technology is analyzed. The traditional transmit selection diversity (TLS, transmit laser selection) technology will cause the frequent switching of the transmitter, and the introduction of the transmission diversity (transmit laser selection) technology will be introduced. The SET (switch-and-examine transmit) technology and the post selective switched polling Technology (SETps, switch-and-examine transmit with post-selection) are used to solve the problem that the emission power of the TLS system is limited by the security standard. The improved dual branch selection (Dual-TLS, dual-branch transmit) is proposed. On) principle and the principle of Group-TLS (Group transmit laser selection). Based on the atmospheric turbulence and the align error complex progressive channel model, the progressive mean symbol error probability and the diversity increase expression of the FSOC system based on the above four transmit diversity techniques are derived. Again, the synchronization of the FSOC communication scene in the two user is synchronized. The performance of the FSOC system based on the multiplexed detector is studied. Two FSOC users define the primary and secondary users respectively. The two are sending data at different power synchronously. For the case of no background radiation noise and the known channel state information of the receiver, the conditional symbol error of the main user and the sub user in the channel state information is derived respectively. The probability of error is calculated and the error probability of the mean symbol is calculated by using the atmospheric turbulence and the align error channel model. Based on the background radiation noise, the decision criteria of the main and sub user data are derived, and the conditional symbol error probability under the channel state information is calculated. Then, the end to end of the hybrid RF/FSOC system based on the relay is analyzed. The radio frequency users in the system use space-time coding technology. The relay nodes adopt fixed gain amplification and forward mode and variable gain amplification and forward mode respectively. The RF link obeys Rayleigh fading, and the FSOC link is affected by atmospheric turbulence and alignment error. We derive the cumulative distribution function of the signal to noise ratio at the end to end of the system, and based on this point. In addition, the asymptotic performance of the fixed gain relay hybrid RF/FSOC system is discussed by using the Meijer-G function in the series expansion of the zero point. Finally, the performance of the FSOC system based on the inexact turbulent channel model is analyzed. The false inexact model is the exact channel gain and Gauss follow. The superposition of the machine variables, and the exact channel gain obeys the Gamma-Gamma turbulent fading considering the alignment error. We first calculate the statistical characteristics of the inexact channel gain, and deduce the expression of the performance indexes such as the interruption probability, the mean symbol error probability and the ergodic capacity of the inexact channel gain FSOC system.

【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN929.1

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