Accurate Adaptive Spectrum Allocation And Arrangement Algorithm In Elastic Optical Networks

With the rapid development of the world,the amount of information to be transmitted in the modern network is increasing at the speed of many times,and the amount of data to be processed in the network is also increasing,especially with the laying and popularization of 5G network,which is a great challenge to the performance of network data processing.For the traditional WDM network,the limitation of its own fixed transmission bandwidth results in the low transmission efficiency.At this time,the elastic optical networks(EON),which has the characteristics of flexible allocation of required bandwidth,come into our vision and gradually replace the traditional WDM network.The bandwidth of traditional WDM network is fixed and immutable,and there is a gap between the bandwidth,which will cause serious waste of spectrum resources.Elastic optical network with higher flexibility has variable bandwidth,and there is no gap between bandwidth and bandwidth.Different bandwidth can be allocated according to the demand of different services to make full use of spectrum resources.In elastic optical network,new industries can be established dynamically A large number of fragmented spectrum blocks will be generated when the old services are removed.These fragmented spectrum blocks are not aligned on the transmission link and are not continuous in the spectrum,that is,spectrum blocks that do not meet the requirements of spectrum adjacency and path consistency are called spectrum fragments.Spectrum fragments will reduce the utilization of network spectrum resources,resulting in a large number of traffic jams,thus reducing network performance.In order to improve network performance,these spectrum fragments need to be collated.The cause of spectrum fragmentation is generally that the transmission request is not directly put into the network for transmission in full combination with the specific situation and transmission request of the existing spectrum resources.When the transmission request is completed,there will be disorderly free spectrum blocks left.Therefore,to solve the problem of disorderly spectrum blocks,we need to start from the source,allocate the spectrum resources before the request is transmitted,and do everything possible The most widely used methods of spectrum resource allocation are first fit(FF),exact fit(EXF)and random fit(RF).Although the resource allocation method based on spectrum resource selection is effective,it ignores the characteristics of network transmission path diversity.If we first select a shortest path from the start to the end,and then combine the spectrum defragmentation method,it may furtherreduce the blocking rate and improve the utilization rate of spectrum resource.In this paper,the D+FF algorithm is analyzed first,and the shortcomings of D+FF algorithm are found: the pure FF resource allocation method can not make full use of the idle resources equal to the size of transmission request.Then,based on the traditional methods of routing and spectrum allocation,some innovations and improvements are made in spectrum allocation,combining spectrum allocation with spectrum resource arrangement,and they are carried out synchronously.A SREXA algorithm combining routing with precise resource allocation is proposed: first use D algorithm to calculate the shortest path,first use Exact Fit(EXF)and then use First Fit(FF)on the shortest path The algorithm allocates resources accurately.In order to cooperate with the steps of resource priority allocation and improve the efficiency of spectrum resource allocation and resource arrangement,a virtual data table is added to record the information of idle resources.The data table records the newly emptied resources.When the transmission information leaves the free spectrum resources,record the location and size information of the idle resources in the data table.If there is a suitable request,please When entering,allocate this idle resource and delete the resource information in the table.When there are multiple adjacent idle resources,these idle resources are combined into a large idle resource,and some paths can free larger idle resources for larger request transmission.Simulation results also show that SREXA algorithm has higher spectrum resource utilization rate and lower request blocking rate than D+FF algorithm,which is of great significance in improving network transmission performance.On the basis of SREXA algorithm,this paper also gets inspiration from ASAMR algorithm,and puts forward ASAMR algorithm which combines multi-path routing with accurate resource allocation: first,use D algorithm to calculate all transportable paths in the whole network,arrange them according to the shortest path to the longest path,first use EXF on the shortest path,then use FF algorithm to allocate resources accurately,such as If there is no available resource in the shortest path,the second shortest path and the third shortest path are used for resource allocation.Like the SREXA algorithm,a virtual data table is added to record the information of idle resources.The simulation results show that the ASAMR algorithm has higher spectrum resource utilization and lower request blocking rate than D+FF and FA-RSA in the medium and high load scenarios,which is of great significance in improving the transmission performance in the high load period of the network.