San Antonio -- AT&T Labs Research raised more than a
few eyebrows at the Society of Cable Telecommunications Engineers' Conference on
Emerging Technologies here, when it detailed a low-cost alternative for broadband-network
upgrades.
Called the 'Mini-Fiber Node,' or MFN, the tiny,
$130-per-home-passed device fits into a housing the size of a four-way tap, and it lets
operators segment their hybrid fiber-coaxial plant into small, 50-home nodes without
having to deal with amplifier respacing or network re-engineering, said Xiaolin Lu, senior
member of technical staff for AT&T's broadband-access-research department.
The MFN uses emerging lightwave techniques to overlay an
operator's existing plant with a fiber-to-the-bridger architecture, Lu said. That
translates into 'abundant, noise-free bandwidth' in both the upstream and
downstream directions.
In the new AT&T approach, operators would install the
MFN after each coaxial line-extender amplifier, then run a separate piece of fiber back to
the headend from each MFN. At the headend, the MFNs are driven by low-cost, uncooled,
Fabry-Perot-style lasers.
Digital traffic running along the fiber is translated from
lightwave back to electrical energy at the MFN, then merged with analog signals on the
coaxial distribution leg.
The approach also frees up extra bandwidth for upstream
communications, which currently cram together in a slim, 35-megahertz slice of bandwidth
between 5 MHz and 40 MHz.
What makes the MFN approach different from other
'fiber-deep' approaches, Lu said, is the fact that MFNs do not include any other
intelligence -- just a converter for translating signals from light to electricity.
'There's no multiplexer, no intelligence -- it's transparent to two-way
traffic, and power consumption is less than 1 watt, so it can be easily powered from the
existing network,' Lu said.
In fact, he added, the bulk of the cost in endorsing the
MFN approach is the fiber deployment itself -- running fibers to each coaxial line
extender.
'Our estimates show that [MFN] including fiber
deployment costs $100 to $200 per home passed, while a traditional upgrade costs $200 to
$400 per home passed,' he said.
Lu showed a slide of a prototype of the new device, and he
said lab tests are under way on an HFC plant in AT&T's lab, as well as in
undisclosed MSO locations.
He did not say when the devices will be commercially
available.
