Optical Connections Magazine Autumn 2018

CHRIS DUNFORD G.FAST TESTING

BEST PRACTICE FOR TESTING SCALABLE G.FAST DEPLOYMENTS T he residential broadband market continues to experience an almost insatiable demand for more bandwidth, driven by services such as over

turning up services on the new network, having a documented benchmark for the entire access network will greatly speed up the identification and resolution process. OPTICAL DISTRIBUTION Like any fibre network, the performance of the optical distribution network will be highly dependent on the quality of the fibre installation. Power loss due to issues with dirty or damaged connectors, poor quality splices and other faulty components can lead to poor customer quality of experience and many wasted man-hours trying to locate and fix the issues. PRACTICE MAKES PERFECT Perform quality testing at every step of deployment. This might be as simple as a connector end-face inspection or optical power measurement, or a more complete characterization of the entire fibre length with an optical time division multiplexer (OTDR). The point is, have a documented plan to ensure nothing gets deployed without being tested. ● Have well established and documented methods of procedure (MOP) which detail every step in the construction and deployment of the fibre network, including detailed procedures for tested at each step. Having these MOPs will ensure consistency and quality across the entire deployment, regardless of which team is doing the work. Additionally, having these MOPs will help define quality acceptance deliverables from any contractors used during the construction. Done properly, this practice will greatly minimise and future issues and if they do arise, minimise the time needed to isolate the root cause. ● Wherever possible, make use of automated, specialised test equipment. Of course, having the right test equipment is essential to quality test results, but there is still the possibility of human error, regardless of how much training has been provided or how detailed the MOPs are. Automation and intelligence, built into the test equipment, will ensure consistent and accurate measurements every time. Whether it’s doing a simple end-face connection inspection or a complex fibre characterization with an OTDR, an automated, intelligent interface allows field technicians of any level to test like an expert. COPPERBOTTOMED ● Just because the copper loops have been shortened, does not mean they require less testing or characterization. Even on short loops, issues like water penetration, nicked or cut cables, even rodent damage can impact performance. Of course, on older plant, these issues are likely to be more prevalent, but they can also be found on new builds.

the top video, online gaming and video conferencing. And while the ‘holy grail’ of access may be fibre to the home, the costs of building and installing FTTH in existing neighborhoods can be prohibitive when compared to the expected average revenue per user. On the other hand, being able to leverage the existing access infrastructure to deliver higher access speeds would provide significant cost savings over FTTH as just about every home already has one or both deployed today. The cable industry continues to make improvements in bandwidth delivered with technologies that now enable 10 Gbps download and 1Gbps upload speeds. For the traditional telephony carriers with twisted pair copper loop access, the problem is that access technologies like ADSL2+ and VDSL2 typically support less than 250 Mbit/s; and even then, only under ideal conditions. Despite this, a recent IHS Markit (formerly Infonetics Research) report still shows that copper access technology continues to dominate market, and will do so for the foreseeable future. Fortunately, the digital subscriber loop (DSL) industry continues to make significant improvements in bandwidth delivered over copper pairs. With the introduction of the ITU-T recommendations G.9700 and G.9701, commonly known as G.fast, speeds of up to 1Gbit/s can be achieved for cable

CHRIS DUNFORD

Chris Dunford , Product Line Manager, Access Business Unit at Exfo. lengths less than 250m. The key to this solution is the deployment of very small form factor, outside plant distribution point units deep in the access network to achieve the shorter copper loop lengths. This fibre to the distribution point architecture solves the bandwidth limitations faced by traditional DSL technologies. However, it also introduces significantly more active optical to electrical conversion sites, into the access network, which need to be tested and monitored. Successful, large scale deployments of FTTdp begin with a strict adherence to best practices for testing and certifying every step of the deployment, both for the optical distribution plant as well as the G.fast copper access plant. With a heavy reliance on external contractors to install and qualify fibre and copper access cables, having a formalised test and acceptance process will ensure a high quality, fully characterised network from day 1. Additionally, if there are issues in

Expensive option? The cost of FTTH can be prohibitive.

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| ISSUE 10 | Q3 2017

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