Variable-length message scheduling algorithms for a WDM-based local lightwave network

Two major difficulties in designing a single-hop multichannel local lightwave network are: relatively large transmitter/receiver tuning overhead and large ratio of propagation delay to packet transmission time. The authors propose several scheduling algorithms which can reduce the negative impact of tuning overhead and schedule variable-length messages. Thus, a long message can be scheduled with a single control packet transmission, instead of being segmented into many fixed-length packets, thereby significantly increasing the system´s efficiency. Three novel scheduling algorithms are proposed, varying in the amount of global information and processing time. Two approximate analytical models are formulated to study the effect of tuning time and the effect of having a limited number of data channels. The system´s performance is found to improve (1) if a simple mechanism is employed to avoid unnecessary transceiver tuning and/or (2) if a predictive transmitter tuning strategy is adopted