Grid Job Routing Algorithms - Phosphorus

Grid Job Routing AlgorithmsUnfortunately, optical amplification is not possible without the generation of amplified spontaneous emission(ASE) noise which can be classified among the most severe impairment that limit the reach and capacity ofWDM all-optical networks. Each optical amplifier contributes ASE, and these contributions add cumulativelyalong the amplifier chain. This accumulated ASE gives rise to signal-spontaneous beat noise at the receiver,which is the fundamental noise limit in an optically amplified transmission system. Each EDFA contributes anamount of ASE [Rama98]:P = 2 hvB n ( G − 1)(1)ASE0spwhere P ASE is the power in an optical bandwidth B 0 , h is Planck’s constant , v is the optical frequency, n sp is thespontaneous emission factor, and G is the optical amplifier gain. The spontaneous emission factor n sp isdetermined by the inversion of the amplifiers Er ions. The contribution of each amplifier’s ASE to theaccumulated ASE is characterized by the amplifier’s noise figure (NF), which at high gain can be approximatedby NF≈2n sp .Following the analysis presented by [Ramam99] the ASE power through the inline amplifiers can be expressedas follows:P ( k, λ ) = P ( k −1, λ ) L ( k −1, λ ) G ( k, λ ) Lase i ase i f i in i tap[ λ ]+ 2. nsp. G ( k, ) -1 hv B . Lin i i o tap(2)and the ASE power through the nodes can be expressed by :P ( k, λ ) = P ( k −1, λ ) L ( k −1, λ ) G ( k, λ ) L ( k) L ( k) L ( k) G ( k, λ ) L2ase i ase i f i in i dm sw mx out i tap+ 2. n .[ G ( k, λ ) -1]. hv B . L ( k) L ( k) L ( k) G ( k, λ ) Lsp in i i o dm sw mx out i tap2. n .[ G ( k, λ ) -1]. hv B L+sp out ii o tap(3)where P ase (k,λ i ) corresponds to the ASE noise power at the k th amplifier and λ i wavelength and L x (k,λ i ) andG x (k,λ i ) are the losses and gain of the various elements through the amplifier chain. The ASE noise variance atthe end of the chain is described by:2 2σ 4 R b P ( N, λ ) P ( N, λ ) B / BASE λ i avg i ASE i e o= (4)where b i is zero or two if i=0 or i=1, R λ the responsivity of the receiver (1.25 A/W), P avg the average signalpower and B e the electrical bandwidth of the receiver. The ASE noise variance will be used to calculate the Qfactor degradation due to ASE.Another constraint on the maximum number of optical amplifiers can be set, that is proportional to the averageoptical power P avg launched at the transmitter and inversely proportional to an acceptable optical SNR min ,Planck’s constant h, carrier frequency u, optical bandwidth B 0 , amplifier gain G and amplifier spontaneousemission noise n sp and given byProject:PHOSPHORUSDeliverable Number: D.5.3Date of Issue: 31/06/07EC Contract No.: 034115Document Code: Phosphorus-WP5-D5.330