Limitations Imposed by Transmission Impairments in the Optical Networks

P. Kulkarni (India), P. Castoldi, and G. Prati (Italy)


Optical networks, transmission impairments, limitations, routing, mesh,and BER


: The impact of transmission impairments on the performance of regular two-connected multi-hop transparent optical mesh (torus) networks in uniform/exponential traffic is assessed, using different routing schemes. A semi-analytical approach is used to find the bit error rate (BER) performance of the network. The fiber links may exhibit different characteristics in terms of these impairments resulting in variation in BER presented by the lightpaths at the receiver. The information so obtained can be used to optimize the routing decision. The transmission impairments (linear and non-linear) may make some routes unusable thereby severely limiting the performance parameters of the network such as optical path length, sustainable traffic, and bit rate. The constraints imposed by the impairments are studied by considering the effect of the impairments individually, as well as by considering their combined effect. Further, these results about the local knowledge of impairments are used to optimize the performance of the network in terms of BER by making the routing algorithm more efficient (ie. constraint-based routing). The transmission performance variation in the presence of a single buffer is also observed. Our results indicate that for a given load the BER performance of single-buffer deflection routing is worse than that of hot-potato. However, for a desired BER of 10-9 the single-buffer helps in significant improvement in throughput. The number of nodes that could be traversed satisfying the BER condition of BER < 10-9 with ASE only is 84 and 18 under hot-potato (HP) and single-buffer deflection (DF) routing respectively, at full load.At a given BER single-buffer has higher throughput than hot-potato.

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