Optimizing Throughput in Optical Networks: The Joint Routing and Power Control Problem

Signal transmission in optical networks suffers from physical layer impairments, which are diversified in nature and cumulative from end-to-end. Such physical layer impairments are critical for successful transmissions, and may significantly affect the network layer routing decisions, hence the traditional divide-and-conquer layered approach would be sub-optimal. In this paper, we adopt a cross-layer approach by taking physical layer constraints into account when performing routing decisions. More specifically, we consider both power losses and nonlinear distortions associated with optical transmissions, and solve a joint routing and power control problem to optimize the system throughput. The joint problem is NP-hard in nature, so we first decouple power setting from path routing by selecting an optimal power setting that transforms the complex power control problem into a simple path feasibility condition, and then propose an efficient Fully Polynomial Time Approximation scheme to tackle the routing complexity. Simulation results show that our proposed algorithm significantly improves the network throughput and greatly outperforms greedy heuristics by providing a guaranteed performance bound at a low complexity.