On the design of optimal TDM schedules for broadcast WDM networks with arbitrary transceiver tuning latencies

We consider the problem of scheduling packet transmissions in single-hop WDM networks, with tunability provided only at one end. Our objective is to design schedules of minimum length for a given traffic demand matrix. The contribution of our work is twofold. First we define a special class of schedules which permit an intuitive formulation of the scheduling problem. We then present algorithms which construct schedules of length equal to the lower bound provided that certain optimality conditions are satisfied. We also develop heuristics which, in the general case, give schedules of length equal or very close to the lower bound. Secondly, we identify two distinct regions of network operation. In the first region the schedule length is determined by the tuning requirements, while in the second it is determined by the traffic demands. The point at which the network switches between the two regions is identified in terms of the number of nodes and channels, and the tuning latency. Accordingly, we show that it is possible to appropriately dimension the network to offset the effects of even large values of tuning latency