Simple Scheduling Algorithms for Use with a Waveguide Grating Multiplexer Based Local Optical Network

As the need for greater bandwidth in local-area networks grows, wavelength-division multiplexing (WDM) is gathering attention as a viable successor to Gigabit Ethernet technologies. In this paper we introduce a new WDM optical LAN architecture based on the waveguide grating multiplexer (WGM) rather than the traditional passive star coupler (PSC). An N-port WGM allows N ² × N ² connectivity via only N physical wavelengths, due to its inherent space-division multiplexing property. Wavelength-routed networks based on the WGM promise to be significant components of future LAN and WAN technologies not only because of their efficient use of wavelengths, but also because they have been implemented as integrated devices. We propose simple, low-complexity TDM schedules for interconnecting MN nodes (M nodes per port) with a WGM in a local environment. Each node is equipped with a single tunable transmitter and a single tunable receiver (both of which can access all N wavelengths). Various transmitter and receiver tuning latencies are considered. We show that, for negligible tuning latencies, aggregate network throughput approaching min(MN, N ²) can be achieved, and for tuning latencies on the order of a packet length or more, throughput on the order of N can be achieved. Since these performance metrics are vastly superior to that of an equivalent PSC-based system (whose maximum throughput is limited by the number of wavelengths, N), we propose that the WGM be considered as an alternative to the PSC for enabling WDM LANs and multiprocessor interconnects.