High speed communication protocols for optical star coupler using WDM

A network with N stations connected via a passive star coupler using wavelength division multiplexing (WDM) is considered. Each station is equipped with a transmitter, transmitting at a fixed frequency, and a tunable receiver, capable of receiving frequencies over the entire transmitting spectrum. Two reservation-based protocols are proposed for a local area network (LAN) environment: the dynamic allocation scheme (DAS), which dynamically assigns slots on a packet-by-packet basis, and the hybrid TDM scheme (HTDM) which is a combination of TDM and the DAS, allowing both preassigned slot and dynamic slot assignment. Analytical results are derived for the delay performance of the two schemes and these results are compared with that of the TDM. It is shown that the performance of DAS is close to optimal when the propagation delay is zero. However, it requires a large signaling bandwidth. On the other hand, HTDM has lower signaling needs, provides lower delays when compared to TDM (particularly under nonuniform traffic conditions), and is capable of handling bursty data traffic. Thus, HTDM offers a more practical solution for implementation for LANs