Coherent Optical Orthogonal Frequency Division Multiplexing (CO-OFDM) basedElastic Optical Network (EON) is one of the emerging technologies beingconsidered for next generation high data rate optical network systems. Routingand Spectrum Allocation (RSA) is an important aspect of EON. Apart fromspectral fragmentation created due to spectrum continuity and contiguityconstraints of RSA, transmission impairments such as shot noise, amplifiedspontaneous emission (ASE) beat noise due to coherent detection, crosstalk incross-connect (XC), nonlinear interference, and filter narrowing, limit thetransmission reach of optical signals in EON. This paper focuses on thecross-layer joint optimization of delay-bandwidth product, fragmentation andlink congestion for RSA in CO-OFDM EON while considering the effect of physicallayer impairments. First, we formulate an optimal Integer Linear Programming(ILP) that achieves load-balancing in presence of transmission impairments andminimizes delay-bandwidth product along with fragmentation. We next propose aheuristic algorithm for large networks with two different demand orderingtechniques. We show the benefits of our algorithm compared to the existing loadbalancing algorithm.
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