by Stephen Hardy
Editorial Director and Associate Publisher, Lightwave
October 22, 2008
Posted by
Stephen HardyAs you'll see in an article that will appear in the November issue of Lightwave, the
working group within SCTE that is shaping the
RF over Glass (RFoG) standards has hit a stumbling block. The group has reached consensus on 1550 nm as the downstream wavelength. However, determining which upstream wavelengths to use has become an issue.
The problem is that the working group, which contains several equipment vendors that also make PON systems, is attempting to construct the specifications in such a way that carriers can overlay a PON over the RFoG infrastructure. Given the wavelengths already in play for GPON and EPON, plus those expected to be used for the 10-Gbit/sec standards now under development within FSAN and the IEEE, there aren't a lot of attractive wavelengths left. And if you can't leverage the volumes that lasers tuned to the already popular wavelengths enjoy, how can you keep costs down?
At the heart of the conundrum is the question of the role RFoG will play on the path toward all-optical MSO networks. One source for my article, whose company currently supplies RFoG-like equipment, asserts that the PON suppliers are pushing an agenda in which RFoG is merely an interim step toward PONs. The source disagrees with this philosophy; his feeling is that RFoG architectures will have a long life within MSO networks, and that the SCTE should therefore focus on what's the most cost-effective way to deploy them, PONs be damned.
Despite this hiccough, consensus indicates that the SCTE working group will complete its task by the middle of next year. But it would appear that carriers could play a very useful role by communicating their viewpoints on the expected relationship (or lack of it) between RFoG and PONs.
