自由空间光通信系统最佳中继布设算法
发布时间：2018-07-31 06:09
【摘要】：自由空间光通信(Free-space optical communications,FSO)是一种通过调制大气中传播的激光来发送信息的技术,其传输速度可以高达几G bps。然而依赖于天气的信道损失和湍流衰落是限制FSO链路距离的两个主要因素。一种解决方案是使用中继。通过引入中继,我们可以将长链路分解成多个短链路,进而减少湍流衰落,提升总的链路距离。因此,最优中继节点布设成为解决问题的关键。本文对FSO中继节点布设进行了深入的研究,主要包括以下几个方面:(1)给出了多跳FSO广播系统的模型,并提出了在非限制条件下的最优中继节点布设算法。在使多跳FSO广播通信的中断概率最小的布设准则下,将中继布设问题转化为无限制条件下的最优化问题。把中继节点位置作为变量,用户节点的中断概率作为目标函数,建立多目标最优化模型。然后把用户节点通信服务优先级作为权重因子,使用线性加权和方法把多目标最优化问题转化为单目标最优化问题进行求解。(2)提出了在没有障碍物和可行域约束条件下,适用于Lognormal和Gamma-Gamma信道模型的两个最优中继布设定理。并理论证明了在发送功率足够大的情况下,最优中继节点应该等距离分布在从信源到信宿的所在的直线上。中继节点的用户数和中继节点的权重对最优中继位置没有任何影响。同时给出了仿真过程,验证了定理的正确性。(3)研究了在障碍物和可行域约束函数条件下,多跳FSO广播系统的中继位置布设算法。在用圆形、椭圆形、线性描述障碍物约束函数,圆形、椭圆形和多边形描述可行域约束函数的基础上,将布设问题转变为限制性条件下的多目标最优化问题。给出了Lognormal信道模型下的最优中继仿真结果,并给出实际工程建议。
[Abstract]:Free-space optical communications (FSO) is a technology to transmit information by modulation of the laser transmitted in the atmosphere. The transmission speed can be as high as a few G bps.. However, the channel loss and turbulent fading of the weather are the two main factors to limit the distance of the FSO link. One solution is to use the relay. By introducing the relay, we can decompose the long link into multiple short links, and then reduce the turbulence fading and increase the total link distance. Therefore, the optimal relay node is the key to solve the problem. This paper makes an in-depth study on the layout of FSO relay nodes, mainly including the following aspects: (1) the multi hop FSO broadcasting system is given. The optimal relay node layout algorithm under non restrictive conditions is proposed. The relay placement problem is transformed into an optimization problem under the unrestricted condition. The relay node position is taken as a variable and the interruption probability of the user node is used as a target function. The target optimization model is used as a weighting factor, and the multiobjective optimization problem is transformed into a single objective optimization problem by linear weighting and method. (2) the two most suitable for Lognormal and Gamma-Gamma channel models under the constraints of no obstacles and feasible domains are proposed. It is proved that the optimal relay node should be equal distance distributed on the line where the source is from the source to the host. The number of the relay nodes and the weight of the relay node have no effect on the optimal relay position. The simulation process is given to verify the correctness of the theorem. (3) (3) the relay location algorithm of multi hop broadcasting system is studied under the condition of obstacle and feasible domain constraint function. On the basis of using circular, elliptical, linear description obstacle constraint function, circular, ellipse and polygon to describe the feasible domain constraint function, the layout problem is transformed into a multi-objective optimization under the restrictive condition. The optimal relay simulation results under the Lognormal channel model are given, and practical engineering proposals are given.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1
本文编号：2154671
[Abstract]:Free-space optical communications (FSO) is a technology to transmit information by modulation of the laser transmitted in the atmosphere. The transmission speed can be as high as a few G bps.. However, the channel loss and turbulent fading of the weather are the two main factors to limit the distance of the FSO link. One solution is to use the relay. By introducing the relay, we can decompose the long link into multiple short links, and then reduce the turbulence fading and increase the total link distance. Therefore, the optimal relay node is the key to solve the problem. This paper makes an in-depth study on the layout of FSO relay nodes, mainly including the following aspects: (1) the multi hop FSO broadcasting system is given. The optimal relay node layout algorithm under non restrictive conditions is proposed. The relay placement problem is transformed into an optimization problem under the unrestricted condition. The relay node position is taken as a variable and the interruption probability of the user node is used as a target function. The target optimization model is used as a weighting factor, and the multiobjective optimization problem is transformed into a single objective optimization problem by linear weighting and method. (2) the two most suitable for Lognormal and Gamma-Gamma channel models under the constraints of no obstacles and feasible domains are proposed. It is proved that the optimal relay node should be equal distance distributed on the line where the source is from the source to the host. The number of the relay nodes and the weight of the relay node have no effect on the optimal relay position. The simulation process is given to verify the correctness of the theorem. (3) (3) the relay location algorithm of multi hop broadcasting system is studied under the condition of obstacle and feasible domain constraint function. On the basis of using circular, elliptical, linear description obstacle constraint function, circular, ellipse and polygon to describe the feasible domain constraint function, the layout problem is transformed into a multi-objective optimization under the restrictive condition. The optimal relay simulation results under the Lognormal channel model are given, and practical engineering proposals are given.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1
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