Light-mesh - A pragmatic optical access network architecture for IP-centric service oriented communication

Contemporary deployments of optical access networks are based on the principles of Passive Optical Networks (PONs). PONs deploy a star topology and dual wavelength for communication between the center and ends of a star. The star topology requires that each end-user be connected to the star splitter (usually a passive coupler). We argue in this paper that while adhering to the requirements of access networks, we are able to provide a better topological solution in terms of the cost-factor and the ability to upgrade to a greater bandwidth. This solution, called a light-mesh, is based on the concept of pragmatic optical packet transport or light-frames results in a unique node architecture, interconnection matrix, and communication protocols. We begin by investigating into the node architecture that is required for a mesh network in the access area. The proposed node architecture has unique benefits in terms of being able to support the intermittent communication in the access area — nodes are not always powered ON, despite which, it is important to maintain mesh connectivity. Hence we propose the use of largely passive components in node architecture design. Passive components in a mesh lead to collisions of packets in the access area, for which we propose a unique collision detection and recovery scheme based on a logical time-overlap method. Collisions make the end-to-end delay uncertain. Analysis of the associated delay is performed. We then propose algorithms to build such a light-mesh network. These algorithms are investigated in terms of network built-out costs and these costs are compared to a PON topology. Cost differences and a performance comparison with PON are presented as part of the numerical analysis. c © 2008 Published by Elsevier B.V.