Recent Advances in Wavelength Routing

• Authors: Christos Kaklamanis
• Venue: SOFSEM '01 Proceedings of the 28th Conference on Current Trends in Theory and Practice of Informatics Piestany: Theory and Practice of Informatics
• Year: 2001

We study the problem of allocating optical bandwidth to sets of communication requests in all-optical networks that utilize Wavelength Division Multiplexing (WDM). WDM technology establishes communication between pairs of network nodes by establishing transmitter-receiver paths and assigning wavelengths to each path so that no two paths going through the same fiber link use the same wavelength. Optical bandwidth is the number of distinct wavelengths. Since state-of-the-art technology allows for a limited number of wavelengths, the engineering problem to be solved is to establish communication between pairs of nodes so that the total number of wavelengths used is minimized; this is known as the wavelength routing problem.In this paper we survey recent advances in bandwidth allocation in tree-shaped WDM all-optical networks. We present hardness results and lower bounds for the general problem and the special case of symmetric communication. We also survey various techniques that have been developed recently, and explain how they can be used to attack the problem. First, we give the main ideas of deterministic greedy algorithms and study their limitations. Then, we show how to use various ways and models of wavelength conversion in order to achieve almost optimal bandwidth utilization. Finally, we show that randomization can help to improve the deterministic upper bounds.