A Study Of Multi-hop Routing And Spectrum Allocation Algorithm In Elastic Optical Networks

Nowadays,many scholars focus on the research of elastic optical networks(EONs).However,while elastic optical network brings flexibility,it also brings new challenges.Due to the existence of different service types,different modulation formats and different frequency gap capacities,it is difficult to control the dynamic situation of elastic optical network reasonably and efficiently.Therefore,the important problem for elastic optical network is how to improve the spectrum utilization of the network on the premise of satisfying the service transmission quality.Among them,the problem of Routing,Modulation Level and Spectrum Allocation(RMSA)is one of the key issues to be solved.The RMSA problem in elastic optical networks is complicated by the fact that in the process of routing spectrum resource allocation,many constraints,such as spectrum contiguity limit,spectrum continuity limit and spectrum nonconflict limit,need to be satisfied.Aiming at the RMSA problem in elastic optical networks,this paper conducts an in-depth study on multi-hop routing and spectrum resource allocation technologies from the perspectives of route selection and spectrum allocation,so as to ensure the quality of traffic request transmission,reduce blocking rate and improve the carrying capacity of the network.The main research contents are as follows:(1)From the perspective of the routing,this paper has proposed a multi-hop routing,modulation and spectrum allocation algorithm based on least nodes algorithm in EONs.Firstly,the algorithm considering the number of nodes on the all routes,finds the least node route in the network,and chooses the shortest distance route under the same conditions.Then,the proposed algorithm divides the shortest distance-least nodes path into a certain amount of short sub-optical paths through optical-electrical-optical converters with multi-hop routing.Finaly,a new lightpath request is independently allocated at the position of available spectrum slots for each sub-optical path according to the distance adaptive modulation technology.This algorithm occupies the least spectrum resources for service requests from the routing selection,thereby improving the spectrum utilization.(2)From the perspective of the spectrum,this paper has proposed a spectrum-and energy-efficient lightpath provisioning with multi-hop routing algorithm in EONs.The algorithm considers the spectrum and spectrum position of the modulation format.Firstly,the algorithm divides entire route into a certain amount of short sub-optical paths.Then,it prefers to select the lowest-level modulation format on the premise of the least number of required slots.Finally,it chooses the position of frequency slot according to the use of spectrum resources on the link.The algorithm can outperform the conventional schemes in terms of blocking probability,spectrum utilization and energy consumption.(3)In the context of EONs,considering both routing and spectrum aspects,a novel adaptive modulation multi-hop routing RMSA algorithm is proposed.The simulation results indicate that our scheme can lower the network blocking probability and achieve the energy efficiency.The spectrum resource utilization is also improved with the acceptable set up delay.