Media access protocols for WDM networks with on-line scheduling

This paper studies media access protocols that support collision-free broadcast/multicast communication for optically connected star-coupled systems with wavelength division multiple access channels. A previous hybrid access protocol, consisting of reservation and receiver channels preallocation, allows reservation for exactly one 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 nonuniform 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, especially in the client-server environment.