Local area networks using a spatial wavelength cross connect1This work was supported by the Natural Sciences and Engineering Research Council of Canada and the Telecommunications Research Institute of Ontario (TRIO).1

Future photonic local area networks may be based upon single-hop architectures using wavelength division multiplexing. Due to optical device limitations however, the number of available channels may not be as large as desired. As a result, spatial wavelength reuse may be required to achieve networks with acceptable performance. One way of achieving this is to use a hierarchical design where a set of local wavelengths is reused in each local subnetwork. The remaining wavelengths are then used to provide connectivity between subnetworks. Although this design can result in very high network capacities, it relies on a high degree of traffic locality, which may not be present in typical local area networks. To address this issue, recently a LAN design was proposed that interconnects local subnetworks across a spatial wavelength cross connect `MANDALA'. The operation of this system however, relies on a single global control channel which may become a performance bottleneck even when the number of channels is very modest. In this paper, we propose some novel designs and protocols for achieving dynamic operation in such a cross connect LAN. The first option uses an associated control scheme for signaling within each local cluster and results in very simple user station designs. The second option employs a spatially reused common control channel for each cluster and requires additional station hardware. Three media access protocols are examined, namely, interleaved TDMA, and two reservation schemes. In the proposed designs, wavelength converter banks are introduced to eliminate the need for dynamic receiver tunability at the user stations. Both capacity and mean delay performance results are presented using analytic and simulation models. It is shown that the proposed systems yield various degrees of dynamic behavior and do not suffer from the performance degradations associated with that of `MANDALA'.