A distributed wavelength switching architecture for the TPON local network

Passive optical networks offer economic Provision Of telephony and low-dain-rate services over optical fibre. Upgrading of these networks by WDM will also bring the possibility of broadband access to customers, and with it the need for broad band switching to interconnect customers in the local network. A distributed switching architecture is proposed for reducing the component quantities needed to implement a local broadband exchange The architecture consists of three stages of switching, The first and third stages of which are distributed throughout the passive optical networks using wavelength routing technique, with only the middle stage implemented in the exchange, using either optical space or wavelength switching. When space switching is employed in the exchange, the distributed architecture almost halves the number of crosspoints, and when wavelength switching is used laser and regenerator numbers are reduced by 40%, compared with die conventional architecture of centralised switching.