The 1G and 10G EPON coexistence
requirement will inherently result in the creation and deployment of a complex PON
systems, where two partially independent transmission systems share a single PON
plant, thus resulting in the need to share both downstream and upstream channels in
a way which eliminates cross-talk and signal quality degradation. As indicated before,
the downstream 1G and 10G data streams will be WDM multiplexed, resulting in two
independent, continuous P2MP channels, separated by a sufficiently large bandwidth
gap allowing for their uninterrupted operation under any temperature conditions accounted
for in the IEEE standard. The 1G downstream link will therefore remain centered
at 1490 nm with the 20 nm window size, while the new 10G downstream link will
have to be allocated somewhere in the 1500??“1600 nm window, where most of the group
participants seem to agree that channel allocation above the current analog video service
delivery band is a better option (above 1560 nm), mainly due to limited non-linear
impairments and lower 10G signal degradation. The commercial availability of laser
and receiver units was already proven by the TF members, indicating that such a channel
allocation can be supported using existing technology.
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