Optical communications network

摘要

An optical communications system comprises an inner core mesh network, 13, a plurality of outer unidirectional ring networks 14 coupled to the core, and passive optical local networks 12 coupled to the outer networks whereby to provide access to terminals 11 coupled to the network. Information is transported across the network using time division multiplexing in combination with frequency division multiplexing; capacity is allocated to particular routes by giving those routes certain frequency/time-slot-within-multiplexing-cycle combinations. A line of the network may comprise a plurality of optical fibres.