Research On Routing And Spectrum Allocation Strategy In Space Division Multiplexing Elastic Optical Networks

With the continuous increase of service demand,the types of service tend to diversify,elastic optical networks(EONs)based on single-core fiber(SCF)have been unable to meet people’s demand,so multi-core fiber(MCF)has been widely studied and used due to its outstanding capacity of expansion.The space division multiplexing elastic optical networks(SDM-EONs)using MCF can provide sufficient bandwidth for services,but it also introduces new problems.Firstly,in elastic optical networks,the transmission of services needs to meet three spectrum constraints,due to these constraints,spectrum resources in the network cannot be effectively utilized and result in the waste of resources,thus reducing the network’s spectrum utilization rate.Secondly,crosstalk may occur between the cores of MCF,when crosstalk is serious,the transmission quality of services will be affected.Therefore,in order to improve network’s performance,it is particularly important to design efficient resource allocation algorithms to optimize inter-core crosstalk and spectrum fragmentation.This thesis mainly studies the resource allocation algorithm considering crosstalk and fragmentation in SDM-EONs.In order to solve the problems of inter-core crosstalk,fragmentation and routing,spectrum and core allocation(RSCA)in SDM-EONs,a dynamic service division integer linear programming(ILP)model for multi-fiber RSCA problem is firstly established in chapter 3,and then a multiple cores allocation algorithm based on crosstalk-avoiding is proposed.In the proceeding stage,the cores are grouped according to the vertex coloring principle and are classified in the same group.In the route selection stage,the algorithm designs the path sorting formula according to the path’s traffic load and hops.In the stage of spectrum allocation,the service is divided according to the same core group’s situation of idle resources and classification,the sub-services are transmitted independently on multiple cores in the same group,so as to reduce crosstalk influence and fragment generation.The simulation results show that the proposed algorithm has better performance in bandwidth blocking rate and spectrum utilization compared with the comparison algorithm.In order to further improve the performance of network transmission,chapter 4comprehensively considers the methods of multi-path transmission and multi-core transmission,and proposes a multi-core and multi-path joint allocation algorithm based on crosstalk and fragment awareness.In this algorithm,the core grouping,core classification and the method of routing selection described in chapter 3 are adopted.In the stage of core group selection,the core group’s service capacity degree is defined according to the relationship between the idle resources in the core group and the size of incoming business,then the group ranking strategy based on the group’s service capacity degree is designed and the core group with the highest value is chosen first.In the stage of spectrum allocation,firstly,the influence of crosstalk on network performance is controlled by setting crosstalk threshold,and the minimum time difference formula of time-domain fragment is considered according to the duration of the current business in the pre-allocated spectrum block and the remaining time of the business in the spectrum block before and after it,the spectrum block with minimum time difference is selected for allocation.Secondly,when the complete service request fails to be allocated in the core group,the algorithm proposes a dynamic service segmentation multi-path strategy based on the maximum capacity of the core group on the first two candidate paths,and the two sub-services independently carry out multi-core transmission on the two paths.Simulation results show that the proposed algorithm can reduce fragments and achieve better performance in bandwidth blocking rate and spectrum utilization compared with the comparison algorithm.