Fiber-to-the-home resurfaces
By Craig Matsumoto
EE Times
(08/31/00, 6:06 p.m. EST)
DENVER — A number of companies are laying the
groundwork to offer residential fiber on a broad scale as
early as next year, according to this week's National Fiber
Optic Engineers Conference (NFOEC). This trend
indicates that the advent of high-speed data access has
revived interest in fiber to the home, after huge costs and
an indifferent public had dashed initial hopes for the
technology.
BellSouth began offering fiber to the home this year, and
company researchers said they expect sales to pick up in
2001. Meanwhile, equipment providers such as Marconi
Corp. plc and OnePath Networks Inc. were at NFOEC to
show off complete fiber-to-the-home architectures. All
three use passive optical splitting to distribute the
high-speed signal to individual homes.
Given the lack of standards for fiber to the home, all three have developed
architectures that include equipment both for the central office and for the home
itself. Some initiatives within the Full Services Access Networks forum are
discussing fiber-optic transmission to the home, but they don't include video. "So,
we believe they are aimed at the SoHo [small-office/home-office] or midrange
businesses, but not at the home," said Ken Neighbors, vice president of
worldwide marketing for OnePath.
Interest in fiber to the home is increasing simply because costs have fallen
enough to make the idea feasible. "The only reason there wasn't fiber to the
home before is because you couldn't meet cost requirements for the service
providers to make money," Neighbors said. "The phone companies would run a
fiber to every home if they could."
BellSouth first studied fiber to the home in 1989 but decided the costs were too
high and the demand too low. The addition of data and video traffic to
fiber-optic feeds, however, has sparked new interest in the technology.
A presentation by Glenn Mahony, a senior member of BellSouth's exploratory
technical group, outlined the regional Bell operating companies'
fiber-to-the-home plans.
The architecture that BellSouth tested in 400 homes last year consisted of a
two-cable feed — one line for data and one for cable TV. The cables used a
1,550-nanometer wavelength of light for the downstream feed and 1,310 nm for
the upstream feed. Telephony wasn't included in the trials.
Both fiber-optic feeds went through two stages of splitters. The first stage
divided the feed into 10 streams that reached poles or pedestals for particular
neighborhoods. Those streams were then subdivided into three streams to reach
individual houses.
Different types of cabling were used at each stage. Standard fiber-optic cables
stretched from the central office to the first splitting stage. From there,
"distribution fiber" was used to reach the second splitting stage, where signals
were assigned to specific homes.
Two cables would connect to each home through a BellSouth fiber interface
device on the outside of the structure. From there, specially characterized inside
cable would carry the signal to the optical network terminal inside the home and
then to PCs and television sets.
The lack of standards for the technology prompted BellSouth to develop much
of its own equipment and, for parts of the architecture, characterize its own
fiber-optic cable, Mahony said.
BellSouth made its first commercial sale of the architecture in June and hopes to
begin volume sales in 2001, but a few touch-ups will be needed. Perhaps most
important is that the separate data and video cables add up to an expensive
installation and will have to be combined in order to make volume deployment
possible, Mahony said.
Marconi displayed its own home-fiber product at the show: a box capable of
delivering voice and video traffic, cable TV and data. Marconi's architecture
also splits the fiber-optic feed in two, but it uses only one cable: Coarse
wave-division multiplexing assigns video feeds to the 1,550-nm wavelength and
voice and data to 1,310 nm.
The system gets its feed from Marconi equipment installed at the central office.
From there to the home, the signals travel across an all-passive network,
meaning the optical signals are not converted into electrical bits and bytes until
they reach their destination. Marconi's solution, like BellSouth's, first delivers the
signal to the general neighborhood and then uses a splitter to send feeds to
individual residences.
The home receives a 10 Base T Ethernet feed for data, cable or set-top video
(depending on the service provider's preference), and multiple lines of
telephony. Marconi has three trials ready to start by the end of the year and
claims to have received eight orders for the system.
OnePath Networks (Princeton, N.J.) is likewise preparing a residential-fiber
product. Unlike Marconi, which drew on expertise with fiber-optic transmission,
OnePath is building on experience with radio-frequency signals, particularly
those from satellite feeds.
OnePath's standard-definition TV product line delivers satellite-dish feeds to
apartment buildings and other multiple-dwelling units, bringing the signal into the
building and then using splitters to deliver it to individual units. Newer versions
of the product have added cable-TV and data feeds.
Based on that experience, OnePath now feels confident it can use fiber-optic
cabling to deliver a multitude of services to the home. The company's
HomePath architecture, which was announced in June, would use one
fiber-optic cable to deliver four telephone lines, a data connection and TV
signals from cable or a satellite dish.
Those signals would all originate at the service provider's central office via a
HomePath box. To send the signals to neighborhoods, OnePath would rely on a
proprietary splitter technology — already in use with SDTV — that can divide a
signal into 16 streams without overly diluting the power to each stream.
Inside the home, OnePath's optical media unit would receive the signals and,
using a "smart splitter," deliver them to the proper appliances. Eventually,
OnePath hopes to provide home networking using this setup, said Neighbors.
Cable companies are particularly interested in HomePath because the
architecture is compliant with the data over cable system interface spec
(Docsis) and would supplant cable modems while adding services. OnePath
plans to demonstrate HomePath at the Western Cable Show in December.
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