Research On Routing And Resource Allocation Scheme Of Free Space Optical Network

Free space optical(FSO)communication technology has received much attention due to its high security,high bandwidth,low cost and high flexibility,which is an important research topic in the field of optical communication and space communication and networking.However,there are many researches on point-to-point FSO communication at present,and the research on networking mainly focuses on the topology design and routing methods of static network,but the research on routing and resource allocation of dynamic network is very limited.With the rapid development of broadband services,mobile Internet and space networks,the routing and resource allocation technology of FSO networks has become a new challenge in this field.Based on the wireless network and Wavelength Division Multiplexing(WDM)network technology,we mainly study the routing and resource allocation methods in FSO network in dynamic traffic scenario.Based on the traffic congestion problem in the dynamic network,we propose a mobile node resource sharing scheme.The specific research results and work are as follows.Firstly,through the investigation and analysis of atmospheric turbulence channel model(Log-normal model)in FSO communication,we obtain the quantitative expression of network link weight,which is applied in the networking research.Because the reliability of FSO link is easily affected by weather,atmospheric turbulence and so on,the design method of high connectivity topology is investigated and applied to network construction.Secondly,based on the analysis of the characteristics of FSO network in dynamic traffic scenario,a mobile node resource sharing strategy based on the node mobility is proposed to solve the dynamic traffic blocking problem.Because of the uneven distribution of traffic in the network,the nodes with rich resources can share the resources with the resource exhausted nodes by the movement of nodes.The strategy consists of two sub-problems:1)The selection of shared nodes.Based on the traffic load and link state,we propose a detailed mobile sharing node selection criteria-NW criterion,and give its quantitative formula;2)The abnormal state that may occur in the process of node movement.Aiming at the problem of link interruption and topology change caused by node movement,we put forward the method of controlling the moving range of nodes,and a straightforward topology recovery algorithm.Simulation results show that resource sharing can effectively reduce the number of blocking nodes and blocking links in the network,and can reduce the network congestion rate.Finally,we study the routing and wavelength assignment problem in WDM network,based on virtual topology reconfiguration,we propose an adaptive routing and wavelength assignment algorithm to ease the traffic congestion.The algorithm uses node resource utilization as an condition to trigger network virtual topology reconfiguration,aiming at avoiding traffic congestion.Simulation results show that the algorithm can effectively reduce the traffic blocking rate and improve the network resource utilization.