PON measurements and monitoring solutions for FTTH networks during deployment and operation

Abstract

Optical fibre step by step substitutes existing copper cable infrastructure in the carriers' access networks, enabling new broadband services. One common approach, a passive optical network (PON) infrastructure, basically consists of optical fibres and splitters, which are lit up by G-PON (Gigabit/s-PON) or XG-PON (10 Gigabit/s-PON). These systems are attenuation limited, therefore the loss budget of a PON is of high importance. For the deployment process the total attenuation of the PON, between Central Office (CO, OLT) and customer site (ONT), must be accurately monitored and kept below the values specified in G.984.x and G.987.x standards. In FTTH scenarios the PON attenuation measurements must include the in-house networks up to the subscriber fibre cable termination unit. During operation, the Optical Line Supervision (OLS) parameters (e.g. G.984.2, Amd2) are continuously monitored, processed and correlated for appropriate alarm generation. In the case of a fibre failure, additionally non-intrusive in-service measurements from the CO site must be supported for fault localisation. This is enabled by an appropriate WDM-filter per PON in the CO, providing access to the PON for OTDR measurements at wavelengths of 1625/1650 nm. In this paper possible solutions for PON measurement and monitoring for the deployment and operation of FTTH networks will be described in detail from a carrier's perspective. All these activities must be carried out in a minimum of time and with low operational efforts in order to guarantee a cost efficient network operation.