Huawei Technologies Co Ltd. says it has developed a prototype optical transceiver with embedded optical time-domain reflectometer (eOTDR) functionality. This could significantly reduce the cost of troubleshooting in fibre-to-the-home (FTTH) networks, the company claims.
An OTDR detects backscattered light in optical fibres and uses this information to compute the location of faults. Traditionally, FTTH maintenance and troubleshooting has to be performed through external OTDR equipment, which requires the test kit to be connected to the fibres under test – a complex and costly operation. There can also be problems “seeing” the network on the other side of the splitters in passive optical networks (PONs) because splitters add attenuation to the optical signal.
Using emulation tests on live networks, Huawei says it has demonstrated that its eOTDR prototype can accurately locate faults to within 5 metres in networks with a split ratio of up to 1:64. The eOTDR technology is ready for commercial use, the company claims.
The OTDR functionality is embedded into an optical transceiver inside the PON optical line terminal (OLT), operating at the same wavelength as the user data. These optical modules are the same size as common optical modules and can be easily deployed in the central office. This approach eliminates the need to reconfigure optical fibres and doesn’t interrupt services, making the troubleshooting process more efficient and less expensive, according to Huawei.
Last year, Alcatel-Lucent also announced embedded OTDR functionality in an SFP module, which plugs into the Intelligent Services Access Manager (ISAM) platform. Its technology can locate fibre cuts anywhere within 20 km in the shared part of the network, but the insertion of a 1:4 splitter reduces the visibility to just 5km from the central office, according to technical documents.
Although Huawei claims that its embedded OTDR module can work with higher density splitters, it’s not yet clear how much the technology is restricted in terms of distance.
By Pauline Rigby
Press release: Huawei Unveils the Industry’s Largest-Split-Ratio eOTDR Prototype