For WDM networks with multi-granularity switching, Optical Tunnel Allocation (OTA) deals with the real-time establishment of optical tunnels between optical nodes through various optical multi-granularity switching devices. OTA is in principle a dynamic Routing and Wavelength Assignment (RWA) problem with multi-granularity switching devices taken into account. In this paper, we propose a novel approximation approach, called Lagrangean Relaxation with Heuristics (LRH), aimed to resolve RWA considering both fiber and lambda switches. Such RWA is first formulated as a combinatorial optimization problem in which the bottleneck link utilization is to be minimized. To tackle the problem, the LRH approach performs constraint relaxation and derives a lower-bound solution index according to a set of Lagrangean multipliers generated through subgradient-based iterations. In parallel, using the generated Lagrangean multipliers, the LRH approach employs a new heuristic algorithm to arrive at a near-optimal upper-bound solution. Through numerical results and comparisons, we delineate that the LRH approach achieves a near-optimal solution, which is profoundly tight to its lower bound, at the expense of low computational time complexity.
|出版狀態||Published - 1 十二月 2003|
|事件||IEEE Global Telecommunications Conference GLOBECOM'03 - San Francisco, CA, United States|
持續時間: 1 十二月 2003 → 5 十二月 2003
|Conference||IEEE Global Telecommunications Conference GLOBECOM'03|
|城市||San Francisco, CA|
|期間||1/12/03 → 5/12/03|