Design of Packet-Switched Access Nodes for Time-Multiplexed Photonic Networks

Photonic networks are probably the most appropriate solution to meet growing bandwidth requirements in the present as well as in the future Internet. The very high bandwidth of optical fibers can be exploited to some extent by multiplexing the data either in the wavelength, in the time or in the code domain. However, new telecommunication applications require a dynamic, high-capacity optical network with the capability to carry heterogeneous network traffic. This cannot be obtained by employing a channel-based or a circuit-switched technique. This thesis concentrates on the design of access nodes for all-optical networks that provide a dynamic high-speed access to the optical fiber. This can be achieved by transmitting data packets in a dynamic manner at a very high bit rate. In order to achieve very high bit rates, the data rate of the packet to be transmitted is up-converted in an optical rate conversion unit located at the node. The packets are then transmitted through the all-optical packet-switched network, while fast optical header processing at the transit nodes allows fast switching, data rate/format transparency, and a low network latency. High-speed subsystems that are required in the network nodes to attain ultra fast bit rates and fast switching on the packet-by-packet basis are investigated in this work. First, a survey on technologies for implementing the high-speed functions and an implementational strategy for ultra fast network nodes are given. The fast optical subsystems including short pulse sources, fast optical switches, header processing and clock recovery units are reviewed. Further, novel techniques for optical rate conversion (i.e., compression and expansion of large optical packets), processing of packet’s header, improvement of transmission efficiency and component/node cascadibility as well as architectures supporting multicast in the optical domain are proposed. Appropriate models based on analytical and numerical methods are exceedingly useful during the design process. Different methods for modelling the components and the main building blocks of an all-optical packet-switched network node are described and used to predict the behavior, interactions, and limitations of the system. This thesis shows that network nodes, when equipped with the proposed high-speed optical subsystems, can provide transmission, reception, and switching of optical packets at high bit rates beyond 100 Gbit/s in an effective manner, and thus can build a dynamic high-capacity packet-switched network capable of dealing with heterogeneous network traffic.