Receiver availability-based technique for highly efficient message prioritization and scheduling in WDM star networks

Abstract

The performance of most scheduling schemes, including the well-known efficient EATS and MSL schemes, is noticeably degraded in practical WDM star networks with non-uniform destinations and non-negligible transceiver tuning latencies. Under these realistic conditions, it is common that two or more messages with the same destination have to be scheduled consecutively or at close times. In most cases, this brings about some performance penalty, owing to the delayed availability of the destination’s receiver for the second (and above) of the consecutive messages. The novel high performance Efficient Message Prioritization and Scheduling (EMPS) protocol is introduced to deal with this problem. EMPS simultaneously considers multiple messages from different transmitting nodes and gives priority to messages intended for the soonest available receivers each time. By balancing the offered load like this, EMPS minimizes the probability of having to schedule two or more messages with the same destination consecutively or at close times. Additionally, by incorporating the Minimum Scheduling Latency algorithm for channel selection, it also minimizes the actual performance penalty, when scheduling of consecutive messages with the same destination cannot be avoided. Extensive simulations are carried out in order to compare EMPS to other efficient schemes under varying conditions. The results show that it always brings about significant performance improvement.