Design And Simulated Implementation Of Adaptive Modulation Routing And Spectrum Allocation Algorithm In Elastic Waveband Switching Optical Networks

With the continuous expansion in network scale and the growing number of applications,the bandwidth demand is booming in a high rate.This makes network resources become saturated,so the efficient use of network resources becomes the focus of network operators.However,in the current Wavelegth Dvision Multiplexing(WDM)optical networks,the main reason of causing the low bandwidth utilization rate is the fixed bandwidth provision,which leads to the granularity mismatch between the user bandwidth requirement and assigned spectral resources.Therefore,the study on elastic optical networks has become a hot topic.By using the orthogonal frequency division multiplexing technology,the fixed bandwidth spacing between wavelength tunnels can be elimated in the elastic optical network that has a wide application prospect since it utilizes spectral resources efficiently.The main feature of elastic optical networks is the capacity of allocating appropriate number of continuous frequency slots according to the actual bandwidth requirement,thus solving the problem of granularity mismatch in the traditional WDM optical networks.This thesis focuses on the problem of routing and spectrum allocation in elastic waveband switching optical networks.A frequency-slot auxiliary graph is proposed based on the idea of graph coloring,which well satisfies the constraints of routing and spectrum allocation in elastic optical networks.A list of routing and spectrum allocation algorithms are designed for elastic optical networks based on auxiliary graphs.For the routing computation,the Dijkstra's shortest path algorithm is utilized.For the spectrum allocation,the first-fit method is used.Meanwhile,some waveband switching strategies are also studied.Three kinds of adaptive modulation waveband grooming strategies are proposed for elastic waveband switching optical networks.Correspondingly,Routing and Spectrum Waveband Modulation Allocation(RSBMA)algorithm is designed.In addition,to deal with the congestion problem,this thesis designs Routing and Spectrum Waveband Modulation Allocation-Time Division Multiplexing(RSBMA-TDM)algorithm by using the time division multiplexing and Markov prediction model.The blocking probability can be further reduced followed by RSBMA-TDM.The main idea of RSBMA-TDM is to predict the ultization of timeslots in the future,which determines the remaining system resources,and thus route and allocate spectrum for traffic.Last,this thesis develops the simulation analysis for the proposed algorithms.Simulation results show that,in terms of reducing optical ports,the proposed waveband grooming algorithm based on time division multiplexing and Markov prediction has good performances.In addition,this algorithm can also reduce the blocking rate.Therefore,our work can be used as a valuable reference to build an elastic waveband switching optical network.