Network coding for optical-layer multicast

The network coding paradigm has become an effective method for achieving efficient multicast in communication networks. The optical community has just started to venture into the application of network coding in optical networks. However, a number of challenges need to be overcome before network coding can be used in optical networks. These include limited buffering and processing capabilities as well as extremely coarse bandwidth granularity. In this paper, we address some of these problems. Finding multicast codes can be broken into two subproblems: finding a subgraph of the topology to code over and then finding an actual code for that subgraph. We show that the former problem is NP-Complete and provide heuristics which allow for coded multicast in optical wavelength division multiplexing networks which offer a modest improvement in bandwidth efficiency over traditional methods for finding routes for optical-layer multicast traffic.