Research On Survivability Strategy Of High Speed Railway Optical Transport Network

As the types of high-speed railway optical transport network services are increasingly diversified,the reliability and real-time requirements of different service types for the network continue to increase.Ensuring the safe operation of high-speed railway optical transport network is the research emphases of railway communication network protection and restoration technology.This paper mainly studies the survivability strategy of high-speed railway optical transport network.To solve the problem of protection and recovery of faults in the optical network,an improved P-Cycle optimized protection technology and ant colony recovery technology based on dynamic routing and wavelength allocation(RWA)are proposed to meet the requirements of service reliability and real-time performance in different scenarios.The main research work is as follows:(1)Improved P-Cycle capacity optimization algorithm(ICOA)is proposed to solve the problem of single link failure under static services.ICOA fully considers the future expansion ability of the candidate cycles when constructing P-Cycle,and improves the actual performance of P-Cycle by introducing the concept of node degree variance.In the COST239 network topology,under the condition that the service capacity is unchanged,the simulation results under different K values are compared and analyzed by comparing the unprotected link ratio and the limit of the adjustable parameter K.The ICOA is superior to the P-Cycle optimization configuration heuristic algorithm(POCA)in terms of P-Cycles number,average protection efficiency,total redundancy,algorithm time,and consumed idle capacity.The ICOA allocates idle resources more reasonable and effectively improves the future expansion ability of P-Cycles.After qualitative and quantitative analysis,the K value which is most suitable for this network topology is selected.(2)Link state based ant colony optimization(LS-ACO)algorithm is proposed to restore the retransmission of services after a multi-link failure.To solve the problem of multi-link failure recovery,dynamic RWA is divided into two issues: routing and wavelength assignment.The wavelength assignment problem is solved by the first fit algorithm,and the routing problem is solved by LS-ACO.LS-ACO adds the concepts of link access rate and link load balancing based on ant colony optimization(ACO),which effectively improves the situation of ACO falling into local optimum,reducesthe service blocking rate and improves resource utilization.After simulation verification,compared with ACO,LS-ACO has reduced the business blocking rate and improved resource utilization rate in two failure scenarios,proving that LS-ACO has better recovery performance.