Web Extras - July 2009
It’s now thoroughly practical to run optical fiber all the way to the home in new builds. Now it’s time to start evaluating the most practical ways of performing an optical deployment. Teresa Bazzle and Mark Conner of Corning Cable Systems discuss how the key can be network access points.
They write: “A key lesson learned from past deployments is the impact that the network access point (NAP) placement strategy has on deployment costs. Placement strategy impacts deployment velocity, installation costs, and the ability to defer component installation until service is needed and revenue is generated. Deferring costs in itself is advantageous, and it’s even more important in situations where the anticipated initial take rate will be low, or where the plant construction may occur in phases.” ...More 
Optical fiber may be immune to many of the problems that plague copper wire, but it is still subject to signal degradation. One type of optical degradation is polarization mode dispersion (PMD), and it’s becoming a bigger problem than previously anticipated. Mike Andrews of Exfo discusses a means of characterizing and alleviating the problem.
He writes: “While today’s network equipment technology can support higher data rates such as 40 Gbps, existing optical links are not necessarily ready for the upgrade, as legacy fibers installed at a time when PMD was not of concern for the prevalent bit rates often exhibit excessively high PMD at broadband speed. Of course, PMD is typically less frequent in newer fibers than in older ones, and solving the problem can temporarily be delayed by avoiding the high-PMD fibers. However, when bandwidth is required, all available fibers will need to contribute. And today, this is more meaningful than ever before, for the following reason: ROADMs make the network reconfigurable, so all fibers are solicited.
“Eventually, the problem must be fixed, either by replacing the whole fiber – a very costly proposition – or pinpointing the worst link sections and replacing only those.” ...More 
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