A simplified optical star network using distributed channel controllers

Future photonic networks may be based on emerging wavelength-division-multiplexing (WDM) technology. In single-hop LAN´s using a passive optical star coupler, stations normally access the network using some combination of wavelength-agile transmission and reception. Unfortunately, this parallel channel architecture tends to increase and complicate the user station hardware and protocols. In this paper, a new network architecture is presented. The objective of the design is to simplify the user stations as much as possible. This is accomplished through the use of a set of distributed channel controllers-one for each WDM channel. The network is thus referred to as the distributed channel controller network (DCCN). The channel controllers assist in the operation of the network in a number of ways. To further simplify the design, bandwidth is allocated hierarchically on each channel. This decouples system operation into two levels. At the higher level, band width partitioning may be done in a static or dynamic fashion. The lower level determines the dynamic use of slots. Two options for media access are considered. The first is a hybrid approach based upon custom hardware-based request scheduling. Allocations are generated by the channel controllers electronically and data transmission occurs using station wavelength agility. The second is much more distributed. Each set of competing stations builds a distributed queue based upon observed requests. It is found that the proposed architecture supports higher throughput than in other similar networks with the same hardware requirements. An analytic model is introduced for calculating mean station delay. Simulations show that it accurately predicts network performance