In this paper, we study the problem of on demand minimum length packet scheduling in single-hop multichannel systems. Examples of these systems are those centered around switching networks, like crossbar switches, and WDM optical ber networks. On demand scheduling require that packets are scheduled upon receipt, and without changing the schedule of earlier packets. On demand scheduling is performed by on-line algorithms. In this paper we show that a large group of online scheduling algorithms, called maximal algorithms, are asymptotically optimal in the worst case sense. This result is established by rst giving the competitive ratio of these algorithms nearly 3, and then by showing that no on-line algorithm can asymptotically perform better in the worst case. Then, we run a simulation experiment on randomly generated problem instances, whose outcome indicates an average increase of the schedule length of maximal algorithms, of 5 with respect to the lower bound.
Maurizio A. Bonuccelli, Susanna Pelagatti