Research On Routing And Spectrum Allocation Strategy In Elastic Optical Networks

With the rapid development of various communication technologies,the Internet data traffic has exploded exponentially,which leads severe challenges for the development of optical networks.Traditional wavelength division multiplexing(WDM)networks have many limitations such as fixed frequency grids and fixed wavelength assignments,which will result in serious waste of spectrum resources.With the introduction of orthogonal frequency division multiplexing(OFDM)technology,the elastic optical network(EON)has extremely fine spectral granularity,which can meet the bandwidth requirements of different service volumes,improve network resources utilization,and reducing network blocking probability,respectively.However,while having many advantages such as high capacity,high flexibility and expandability,EON also means that the allocation and management of spectrum resources becomes more and more difficult.This thesis focuses the routing and spectrum allocation issue in EONs,and proposes improved algorithm strategies with theoretically analysis and simulation methods.This thesis first introduces some basic concepts and key technologies of EON,and then discusses the routing and spectrum allocation(RSA)problems in EONs.An improved routing and spectrum allocation algorithm for the maximum spectrum block completeness is proposed.The improved algorithm will select several candidate routes by using the k shortest path strategy firstly.Then,the spectrum block completeness will be calculated,and the least spectrum fragments or the remaining available spectrum slots are selected.The simulation results show that the improved algorithm has less fragmentation and lower network blocking probability compared with the traditional RSA algorithm.In addition,a spectrum allocation strategy based on optimized disjoint connection group is proposed.By sorting the services that arrive in a period of time,the request in the disjoint connection group is allocated via priority.Then the remaining request that have the same link are placed in the non-disjoint connection group,which adopted by the corresponding spectrum allocation policy.Simulation result shows that the spectrum allocation algorithm can provide more continuous available frequency slots for high bandwidth and multi-hop route demand.It is significantly reducing the bandwidth blocking probability.