Protocols to eliminate tuning penalties for packet-switched WDM star networks with large tuning latency

The use of low-speed tunable devices may lead to throughput and delay penalties for packet-switched WDM star networks. When the tuning latency is significant, conventional cost-effective solutions result in significant throughput and delay penalties. Our approach: (i) combines and unifies existing approaches to improve performance by pipelining multiple tunable filters per node and making a TDM schedule with maximum time gap for reception; (ii) introduces ‘superpackets’ (multiple packets with the same source and destination), thereby relaxing the impact of large tuning latency. Since the superpackets increase throughput at the cost of increased delay, we determine the minimum delay, under a constraint of no throughput penalty. A discrete-time queueing model of the protocol shows that a system with two tunable filters per node has low delay and is wavelength-efficient for uniform traffic.