Research On FPMIPv6 Handover Scheme Based On Dynamic Access Point Selection In FSO Network

Because of multiple advantages such as high bandwidth,high security and flexible networking etc.,free space optical communication(FSO)has attracted more and more attention.With the increase of user networking requirements,point-to-point FSO communication cannot support uninterrupted global domain information transmission.The research direction of FSO communication has shifted toward networking.However,the narrow beam of laser and the constrained access degree of optical node limit the development of mobile FSO networks,especially in the aspect of handover.Handover is a key research issue in wireless networks.However,there are few related researches in FSO networks,and the two communication methods are quite different.Existing wireless handover methods cannot be directly applied to FSO networks.This paper analyzes the characteristics of FSO networks.Based on the above,the FPMIPv6 handover method based on dynamic access node selection in the FSO network is mainly studied.When the moving wireless optical node leaves the current access point and enters the communication range of the new access point,handover of the access point may occur.In order to determine when the handover operation starts and guarantee enough time for the handover operation,this paper proposes a dynamic handover decision threshold,which determined by the mobile node's moving speed and handover delay.When the communication distance between the mobile node and the current access point is equal to the distance decision threshold,the handover operation starts.Aiming at the problem of narrow laser beam and restricted degree of access point in FSO network,this paper proposes a dynamic access node selection method.The current access point tracks and predicts the motion information of the mobile node by EC-EKF algorithm.It solves the problem that the mobile node cannot receive signals from surrounding nodes and compare the signal strength to select the best access node.When the communication distance between the mobile node and the current access point triggers the decision threshold,a fuzzy logic system is introduced.Through the fuzzy logic system to comprehensively consider three factors(the received optical power of the mobile node,the relative motion angle,and the access degree of the candidate access point)and select the best access point.Finally,the dynamic access point selection method is simulated by Matlab.The simulation results show that,compared with the traditional access point selection method,the proposed dynamic access point selection method can effectively select the best access point and reduce thenumber of handovers.In the network layer handover of the mobile node,this paper introduces the FPMIPv6 handover method,and proposes a FPMIPv6 handover method based on the dynamic access point selection based on the FSO network.The method adopts a dynamic access point selection method to select a new access gateway and solves the problem that the mobile node cannot obtain new access gateway information.Based on the FPMIPv6 handover method,the bidirectional tunnel between the previous gateway and the new gateway is canceled,and the mobile node cache is established in the local mobility anchor point,which reduces the handover delay and packet loss rate caused by bidirectional tunnel establishment and FMIPv6 predictive handover failure.Finally,the improved FPMIPv6 handover method is simulated by NS2.The simulation results show that,compared with the FPMIPv6 handover method,the improved FPMIPv6 handover method in this paper can effectively reduce handover delay and packet loss rate.