Multiwavelength technology for local loop applications

Abstract

Optical networks employing s i n g l e mode f i o r e i n a passive t r e e o r star-bus architecture are being considered f o r a p p l i c a t i o n i n the l o c a l network environment. I n a d d i t i o n t o economic advantages a r i s i n g from resource sharing these networks have the advantage o f providing a continuous photonic path between the l o c a l switching centre and the customer. This allows o p t i c a l wavelength r m l t i p l e x i n g techniques t o be used t o gracefully upgrade the network and t o share the capacity o f the f i b r e medium amongst many customers. 1. I n t r o d u c t i o n Penetration of o p t i c a l f i b r e technology t o the customer w i l l o f f e r major p o t e r t i a l f o r the p r o v i s i o n o f a wide range o f new services w i t h bandwidths well beyond the a b i l i t y o f m e t a l l i c twisted p a i r technology t o provide. There i s a major debate world wide about the i n f r a s t r u c t u r e of the o p t i c a l network a r c h i t e c t u r e t o d e l i v e r the new generation of services. The issues are a complex mix o f technology, economics, service demand, timescales, service penetration and regulatory conditions and t h i s debate i s w e l l beyond the scope o f t h i s paper. Here we w i l l examine the a p p l i c a t i o n of WDM technology f o r one class of proposed architecture. exchange cabinet customer terminal U optical splitters a) Passive multi-star exchange cabinet b) Passive star-bus Fig. 1. Passive shared access networks The passive shared access architectures, see f i g 1 f o r examples, are beinq studied i n several countries (eg. r e f s 1,2&3). The p a r t i c u l a r advantages of t h i s network are: a. Significant resource sharing o f the upper reaches of the network allowing a greater proportion of the c a p i t a l cost o f the i n f r a -s t r u c t u r e t o be allocated t o the customer network termination u n i t . customer, enabling future upgrading by a d d i t i o n o f d i f f e r e n t o p t i c a l wavelengths t o carry new services without d i s t u r b i n g e x i s t i n g services o r e x i s t i n g customers not r e q u i r i n g the new service. b. A continous o p t i c a l path between the switching centre and the c. The shared access topology i s also i d e a l l y suited t o the provision of broadcast type services such as entertainment t e l e v i s i o n .