Slot contention resolution for distributed TDM scheduling in an optical star network

In this paper, we study slot contention resolution in single-hop TDM/WDM star WANs. In this network multiple ingress switches are connected to an all-optical cross connect switch (core switch). The ingress switches transmit traffic in fixed slots to the egress switches via the core switch. There is no coordination among the switches so we expect some contention in the core switch. We assume two types of traffic namely the expedited forwarding (EF) and the best effort (BE). The ingress edge switches randomly transmit traffic in time slots similar to the slotted-ALOHA. Our core switch is a cross bar switch. Since there is no coordination among the ingress switches, different contention resolution and avoidance techniques can be implemented to eliminate the contention at the core. Schemes using shared-per-node wavelength converters (WC), neighbor deflection routing and extra wavelengths are explored