Optical WDM Network Planning Using Heterogeneous Multi-granularity OXCs

Multigranular optical WDM network aims to reduce network cost by grouping multiple wavelengths and then switching those wavelengths together at waveband or fiber levels. To configure such multi-granular network, we have two choices-homogeneous network and heterogeneous network. The former applies only a single type of optical cross connect (OXC) while the latter allows different types of OXCs. Due to the demands varies and change asymmetrically geographically, networks with heterogeneous OXC nodes is especially suitable for placing best switching types at different location. In this paper, we aim at the design of an algorithm to solve the network planning problem in optical network with heterogeneous multi- granularity OXCs. The planning program determines not only the switching granularity for each node but also determine the routing and wavelength assignments to satisfy the given demands. The contributions of the paper are four folded. First, we propose a graph model to represent the OXC node. The transformed graph simplifies the representation of node structure and helps to model the problem. Secondly, we propose a mathematical formulation to model the network planning problem as an ILP problem. Thirdly, a Lagrangean relaxation based heuristic algorithm is proposed to obtain a near optimal solution. Fourthly, we studied the impact of waveband size on network cost. This work reveals that the waveband size plays a crucial factor. The proposed algorithms can determine the optimal number of waveband size.