something to chew on this morning.
eetimes.com
Crossing the PONs: vendors push fiber for
last mile
By Brian Fuller
EE Times
(02/01/01, 3:42 p.m. EST)
WASHINGTON — Little more than a year after fiber became the latest
answer for the network's last mile, vendors came to ComNet to tout
the architecture as an increasingly cost-effective way to bring
significant bandwidth to the home and business.
Calling passive optical networks "the future of the network," Darryl
Ponder, chairman and chief executive officer of Optical Solutions Inc.,
bluntly told his audience last week, "String it, bury it and its lifetime is
at least 35 years."
The idea behind passive optical networks, or PONs, is simple: take the
superfast bandwidth of the backbone, which tends to terminate at the
central office switch, and shunt it into homes and multitenant
dwellings. For homes, it means instant broadband and no more hassling
with the service of digital subscriber line vendors or cable companies.
For small- to medium-sized businesses, the vast majority of North
American companies, it means they can get the same kind of
bandwidth as their much larger, better-heeled competitors.
The $10 billion communications-access market in 1999 is expected to
grow to $18 billion by year's end, some analysts predict.
Steve Hersey, manager of product planning at Quantum Bridge Communications (Andover,
Mass.), said that 76 percent of all midsized businesses are within a mile of an available
fiber source. "There's plenty of fiber, but what hasn't existed is a way to leverage that
fiber and fan it out to customers."
In one architectural scenario, put forth by startup Terawave Communications (Hayward,
Calif.), an optical line terminal, generally a central office or point of presence, shunts the
signal from a 15xxnm through a passive optical power splitter and into optical network
terminals in the home or business. The return path comes back on a 1,300-nm laser and
into a 1,310-nm burstmode receiver back at the optical line terminal.
In this scheme, there are no intervening elements between the optical line terminals and
the optical network terminals. That eliminates active elements between the two points,
reducing the need for costly powering, right-of-way space and maintenance for
electronics equipment.
The Full Services Access Network Consortium (FSAN) has proposed an ATM-based format
for PON, which has been accepted by the International Telecommunications Union as
ITU-G.983. In addition to being ATM cell-based, the system is symmetric (allowing 155.52
Mbits/second upstream and downstream), a 20-km range and single- or dual-fiber
operations.
While there was no counterpoint at last week's panel sessions, hurdles do exist in the real
world. The laying of new fiber in some places can cost up to $300,000 a mile, and even
the cost of "lighting" a single strand of fiber (even if the fiber exists in the ground) can be
thousands of dollars in the first year. Labor can be more than 50 percent of
implementation costs.
Then there are the inevitable standards clashes to come. While some companies, such as
Terawave, back FSAN's approach, others are pursuing proprietary approaches.
Still, Ponder sees costs falling as quickly as demand for bandwidth is growing. A
fiber-to-the-home solution, for example, cost about 20 percent more last year than a
hybrid fiber-coax solution, he said, compared with a 10-15 cost delta now. "2001 will be
the year that FTTH is less expensive that HFC," he said.
He estimates that the deployments of fiber to the home, roughly a million last year, will
jump to as much as 9 million in four years.
Several long-time players in the European Full-Service Access Network standards effort
are taking note of the rebirth in PON interest led by startups like Quantum Bridge and
Terawave. Infineon Technologies, for example, is launching a corporate-wide effort to
meld its talents in fiber optic components and mixed-signal ICs with the PON-centric DSP
efforts launched by its Savan division (Netanya, Israel). Shlomo Berkovitch, president of
the Savan group, said that Infineon's early base of expertise was in ATM transport over
passive optical, but the company is renaming its effort "xPON," with the understanding
that Ethernet or Sonet transport may be used for PON networks.
Among the programs Infineon can apply to xPON are its work in bidirectional fiber
transceivers, including components that support both in-band and out-of-band signaling,
and a patented method of carrying symmetrical 10-Mbit Ethernet over VDSL, developed
with 3Com Corp., called 10 Base S. Bob Pierce, vice president of sales and marketing for
communication products at Infineon, said that the interest at the ComNet show in
prototype 10 Base S designs had exceeded expectations, "with customers coming to us
with new ways of using this transport."
"Our xPON program is indifferent to where the service providers terminate the fiber
services — curb, home or building," Berkovitch said. "We can supply reference IADs
[integrated access devices] for the access market, and depending on the economics of a
home gateway, we may see CPU-less models of IADs become popular for a PON network." |
