High Utilization of Wavelengths and Simple Interconnection Between Users in a Protection Scheme for Passive Optical Networks

A novel protection architecture for passive optical networks (PONs) is presented and evaluated. It is based on the cyclic property of arrayed waveguide gratings (AWGs) and the interconnection between two adjacent optical network units. The proposed scheme is compatible with both wavelength-division-multiplexing (WDM) PONs and hybrid WDM/time-division-multiplexing PONs. It is compared with two existing schemes and shown to have several advantages: 1) 50% less wavelengths is needed; 2) the fiber interconnections are simplified; 3) the connection availability is improved by one order of magnitude.

I. Introduction

Passive Optical Networks (PONs) with wavelength-division-multiplexing (WDM) technology (such as WDM PON and hybrid WDM/time-division-multiplexing (TDM) PON [1]) can provide a promising solution for broadband access. High utilization of wavelengths is desirable to support more subscribers in access networks since the total number of wavelengths (offered by commercially available light sources) is limited. Furthermore, access networks are very cost-sensitive. Because network operators need to guarantee the level of connection availability specified in the service level agreement it is important in PON deployment to minimize the cost for protection while maintaining the connection availability at the acceptable level.