A Study Of Routing And Spectrum Allocation In OFDM-based Spectrum Flexible Optical Network

Currently, the rapid growth of Internet IP comes up with the higher requirements fortransmission capacity and bandwidth demands. In order to meet the demand of explosive growingtraffics, wavelength division multiplexing (WDM) technology has been widely used to improve thetransmission capacity of optical fiber. However, the traditional WDM optical network is not flexiblein the spectrum resource management, resulting in the serious waste of bandwidth resource in thewhole network, which does not meet the needs of the huge capacity and high rate in the futurenetwork. Because it is lack of bandwidth flexibility in the WDM optical network, researcherspresent the spectrum sliced flexible optical networks with the features of high spectrum efficientand strong scalability.This paper studies the problem of routing and spectrum allocation (RSA). The routingselection sub-problem is solved by the K shortest path algorithm and the spectrum allocation issolved by the First-fit algorithm. The K shortest path algorithm finds k candidate paths betweeneach pair of nodes according to the given physical topology. Because the time complexity is toohuge in the integer linear programming (ILP) algorithm, load balancing spectrum allocation (LBSA)heuristic algorithm is proposed in this paper. The LBSA algorithm can balance the load in each link,and decrease blocking rate. Finally, in the experimental simulation, the superiority of load balancingspectrum allocation algorithm is verified in the NSFNET and Torus4*4physical topology networks.In addition, by relaxing the constraints of spectrum contiguity, the paper gives a new viewpoint toimplement routing and spectrum allocation problem. It can reduce the waste of the spectrumresources without considering the spectrum contiguity, which is verified by numerical simulation.