Research On Fairness Resources Assignment Issues In Elastic Optical Networking

The exponential growth of network traffic requires larger network bandwidth and more flexible resource allocation.At present,some new technologies of optical network are proposed,such as Elastic Optical Network(EON),Flexible Wavelength Division Multiplexing(FWDM)network and so on.The core technology of the EON is optical orthogonal frequency division multiplexing(OFDM),which has been extensively studied due to its high spectral efficiency and high flexibility of spectrum assignment.In the EON,Routing and Spectrum Allocation(RSA)in the realization of EON has become a hot research topic.There are two common problems that reduce service efficiency and cause a negative impact on its sustainable development,which are unfairness between different bandwidth requests and spectrum fragmentation.However,a large number of literatures focus on the study of spectrum fragmentation.In this work,we focus on achieving service fairness performance without significant blocking-performance deterioration.It is well known that larger bandwidth services are more difficult to find the appropriate light path under the spectrum continuity and adjacency constraints,if no special bandwidth allocation mechanism is taken.This means that high-bandwidth traffics may suffer from higher blocking probability.That's the fairness issues of request granularity in elastic optical networks.There are two fairness resource allocation schemes designed to solve the fairness issues of request granularity in EONs: The Advanced Fairness Aware RSA algorithm and the Joint Fairness-Aware and Fragmentation-Reduction RSA algorithm.We introduced the algorithm process in detail and analyzed the performance of the schemes through the OPNET simulation software.The results show that the two schemes can both improve the network fairness index well but bring different damage of the blocking rate.The importance of service level is obvious in communication and network systems.We consider both request granularity and grade when spectrums are allocated.A generalized fairness algorithm based on the joint algorithm has been proposed to solve the fairness problem of the network with different classes of users.The simulation shows that,after considering the request grade,the flexibility of spectrum assignment is improved.The scheme can adapt to a variety of the network system and make the resources assignment more flexible and differential.In the recent study,the fairness allocation scheme in elastic optical networks is generally based on static shortest routing.However,adopting the dynamic routing can improve the utilization ratio of network resources and widen extent of application,and the impact of dynamic routing is seldom studied.Therefore,the fairness RSA schemes based on dynamic routing is studied in the last part.The fairness-aware RSA scheme based on dynamic routing is designed and the advantages and disadvantages of the scheme are analyzed in terms of blocking rate and fairness index.Simulation results show that the scheme can apply to the network scenarios whose vertex loads is different.