Grid Job Routing Algorithms - Phosphorus

Grid Job Routing AlgorithmsCrosstalk (XT)Crosstalk is introduced in WDM systems when leakage of optical signals generated throughmultiplexing/demultiplexing, switching, and other optical components interferes with the data channels,imposing power penalties in the system. Therefore, the level of crosstalk introduced across an optical path isclosely linked with the node architecture and the technologies of the elements comprising the nodes. In oursimulation network we considered an OXC based on the wavelength selective architecture that is depicted inFigure 4.1. Two types of XT arise in WDM systems: inter-channel (inter-band) and intra-channel (intra-band).The former is when the interfering XT element is on a sufficiently different wavelength compared to thewavelength of the desired signal so that the difference in wavelength between the signal and the XT element islarger than the receiver’s electrical bandwidth. The latter occurs when the interference is on the samewavelength or sufficiently close with the desired signal so that the difference in wavelengths is within theelectrical bandwidth of the receiver.We consider only intra-channel crosstalk as its effect is much more severe compared to inter-channel crosstalkand we study crosstalk in conjunction with ASE, since both impairments are very closely related to the power ofthe signal traversing the OXCs. The amount of energy that leaks to neighbouring wavelengths is described bythe signal-to-crosstalk ratio (X sw ) and is expressed as [Ramam99] :J kP ( k, λ ) = ∑ X p ( j, k, λ ) L ( k) L ( k). G ( k, λ ) L(9)XT i sw in i sw mx out i tapj=1where p in (j,k,λ) is the power of the jth co propagating signal at the switched shared by the desired signal, and J kis the total number of crosstalk sources at the kth node.WavelengthDemultiplexersWavelengthMultiplexersλ11N f MMMMMM1λ2λ3λMN fTxRxDigital Cross ConnectFigure 4.1: Node architectureFinally the noise variance of crosstalk is described by [Ramam99]:Project:PHOSPHORUSDeliverable Number: D.5.3Date of Issue: 31/06/07EC Contract No.: 034115Document Code: Phosphorus-WP5-D5.332