Optimisation of layer rate and wavelength allocation based on network coding for multirate optical multicast

Layered multicast, one of the multirate multicast, is effective in optimising network throughput for heterogeneous WDM (wavelength division multiplexed) networks. Compared with single layer multicast, layered multicast can achieve the maximal network throughput, making each layer multicast member receive the data with its maximal capacity. However, how to optimise each layer rate for multirate multicast network is a classical NP-hard problem. In this study, the authors propose a layer rate optimal allocation algorithm based on network coding (NC-LROA) to get the optical multicast network maximal throughput and to reduce wavelength number required by multicast. In the NC-LROA algorithm, the multicast layered rate is optimised with the heuristic algorithm, which runs to reachable network maximal throughput rather than the minimal value in each destination node´s maximal flow. The authors use the network coding to compress the transmitting information among wavelength channels, which have high links sharing degree so as to improve wavelength utilisation. The high sharing degree links have the priority to assign wavelength bandwidth in the inter-layer multicast routing. Simulation results show that the proposed algorithm can, by optimising the layer rate, get network maximal throughput and at the same time reduce the wavelength bandwidth consumption for the optical multicast network.