Media Access Protocols for WDM Networks with On-Line Scheduling

This paper studies media access protocols which support collision-free broadcast/multi-cast communication for optically connected star-coupled systems with Wavelength Division Multiple Access channels. An early hybrid access protocol, consisting of reservation and of receiver channels pre-allocation, allows reservation for exactly one WDM channel per node during the reservation phase. We extend this protocol by allowing reservations on multiple channels and applying scheduling algorithms to improve network performance. Existing scheduling algorithms for similar reservation problems, although providing optimal scheduling for network utilization, have unacceptable computational cost and high implementation complexity. We propose two on-line scheduling algorithms which run in linear time and are simple, making them amenable for hardware implementation. Performance of the protocol using scheduling with varying system parameters is evaluated through discrete-event simulation under both uniform and non-uniform traffic patterns. Our simulation results show that our approach achieves lower average packet latency and higher network utilization compared to the early hybrid access protocol with single channel, especially in the client-server environment. Keywords— WDM Networks, Star topology, Media access protocols, Reservation, and Pre-allocated receivers, On-line scheduling.