Helios-2 an all-optical broadcast local area network /

by Singhai, Mrugendra.

SINGHAI, MRUGENDRA. Helios-2: An All-Optical Broadcast LocalArea Network. (Under the direction of Dr. Mladen Vouk and Dr. George Rouskas.) This thesis describes the details of a new network architecture called Helios-2. It is based on the Hiper-l protocol, a reservation protocol designed to coordinate access to the various channels of a singlehopbroadcast-and-select wavelength-division multiplexing local area network. The Helios-2 network consists of a number of nodes connected through a passive all-optical star coupler which allows a broadcast network. Communication among the nodes in Helios-2 occurs using a scheduled access to the network medium i.e. optical wavelengths. For a single-hop broadcast-and-select network to be efficient, the bandwidth allocation among the nodes must be dynamically managed. Although a number of protocols have been proposed for this purpose they all suffer from inefficiencies of operating in environments with non-zero processing, tuning and propogation delays. Helios-2 is designed to overcome these inefficiencies. This work presents different elements of Helios-2 architecture: its state machines, communication frame formats and contents, scheduling algorithm and possible hardware architecture. These elements are optimized for a total hardware based implementation. The Helios-2 Master State Machine, which controls the operation of a node ina Helios-2 network, has five major operation modes: Time Measurement, Join, Election, Routine and Scheduling. Master state machine controls the operation of the receive and transmit auxiliary state machines of each node. Helios-2 uses the concept of " Virtual Receivers” to achieve non-preemptive scheduling. " Virtual Receivers” are a set of physical receivers that behave identically in terms of optical tuning. A scheduling algorithm, which is at the heart of Helios-2 network operation, is optimized for hardware based impl ementation. Simulation was used to evaluate the behaviors of the scheduling algorithm. It was found that the scheduling algorithm proposed here produces schedules very close to optimal schedules. Finally, an example hardware implementation for Helios-2 is outlined. Implementation would have a FPGA back end and an Optical front. FPGA back end consists of a host interface, Helios-2 state machines and transceivers that interface with optical front end. Optical front end is based on a Dense Wave Division Multiplexing Slowly Tunable Transmitter - Fast Tunable Receiver combination. The front end may have either optical tuning or electronic tuning. HELIOS-2 AN ALL-OPTICAL BROADCAST LOCAL AREA NETWORK by Mrugendra Singhai A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the Degree of Master of Science Computer Engineering Raleigh 2002