Optical Fibre Bus Protection Architecture for the Networking of Sensors

A novel optical fibre bus network for the multiplexing of sensors, which can recover from one or more point failures in the fibre, is presented. We describe how protection switching can be performed so that it satisfies three simultaneous criteria: 1. the network can survive at least one failure at any location, 2. the propagation losses are nominally equal for all channels, both before and after protection switching, and 3. it is possible to signal the presence of the failure and the required remedial actions without using external network resources. We explain how well known telecommunications protection categories can be applied in the context of sensor networks and we argue that "dedicated line" and "dedicated path" protection are preferable in most circumstances. The two categories of dedicated protection allow the failed fibre segment to be remotely determined merely by monitoring the presence or absence of the channels arriving at the network's receiver node.