A cluster of vendors led by Cisco Systems Inc. and Broadcom
Corp. took the wraps off a wireless technology last week that they hope will put MCI
WorldCom Inc. and Sprint Communications Co. on course to challenge cable in the
broadband-services arena.
If the new wireless-broadband system -- targeted for
multichannel-multipoint-distribution-service spectrum and other microwave tiers -- works
as planned, it will allow MCI, Sprint and other players in fixed-wireless services to
deliver a full slate of video, voice and high-speed data to homes and small businesses
without stinting on coverage or service variety.
"The most encouraging part of this development is that
it really validates our choice of wireless as a medium for delivering broadband services
to the mass market," Sprint spokesman Russ Robinson said.
Underlying the new wireless-broadband platform is a
technology known as "vector orthoganal frequency-division multiplexing,"
developed over the past four years by Clarity Wireless Inc., which Cisco acquired one year
ago.
Cisco is making the technology available free-of-charge to
Broadcom and other chip-makers in an effort to establish it as a de facto industry
standard that maximizes the broadband-service potential of microwave-based delivery
systems, director of marketing for broadband fixed wireless Steve Smith said.
"Our game is to get fixed wireless moving as a viable
competitor to cable and DSL [digital subscriber line]," Smith said. "We've
chosen this technology as the one to back because it delivers both a higher spectral
efficiency and a higher link efficiency than anything we've seen."
Broadcom -- which is supplying chips for the current
wireless-broadband market, founded in QAM (quadrature amplitude modulation) and QPSK
(quadrature phase shift key) technologies -- is swinging behind VOFDM for the same reason,
vice president of marketing Tim Lindenfelser said. "This technology overcomes the
severe line-of-sight and other limitations of other approaches to MMDS," he added.
While MCI and Sprint plan to launch next-generation
wireless-broadband systems as soon as the first quarter of 2000, Broadcom will be in a
position to supply VOFDM chips to systems and customer-premises-equipment makers early
enough next year to meet deployment schedules for most carriers' wireless-broadband
deployments, Lindenfelser said.
Robinson said that while the new system offered
"exciting" possibilities, Sprint has issued a request for proposals for initial
market build-outs, and it would be unfair to vendors responding to that RFP to give an
unqualified thumbs-up to a new system that has yet to be fully tested.
"We've looked at [VOFDM], and we are looking
forward to what these guys come up with," he added.
Together, MCI and Sprint have secured control of MMDS in
120 markets representing 60 percent of U.S. households, with 80 markets now falling under
Sprint's umbrella, Robinson said. By the end of the second quarter, Sprint plans to
have 10 cities operational on the new wireless-broadband platform, which starts with
high-speed two-way data and one-way cable and later adds voice services, he added.
"We'll be operational in 30 markets by the end of
2000," he said. The first 10 include Phoenix, San Francisco and Detroit -- where
companies acquired by Sprint were already operating -- as well as seven other markets to
be named later.
The new "BCM2200" ASIC (application-specific
integrated circuit) -- which combines VOFDM technology and media-access control in a
single chip -- will be priced low enough to allow manufacturers to deliver customer
equipment at costs nearly on par with cable gear, Lindenfelser said.
"The main difference [in cost] is the antenna,
although there's some trade-off there with the cost of the tuner that's required
in cable," he noted.
Lindenfelser declined to set a delivery date for commercial
product, but he said samples of the new ASIC would be available to manufacturers in the
first half of 2000.
One reason why Broadcom can proceed so fast and so cheaply
is because it is tapping the same MAC technology used in DOCSIS (Data Over Cable Service
Interface Specification) chips, officials said. They also noted that the VOFDM technology
has gone through several development phases over the past four years, giving the partners
confidence that any further design refinements before volume production would be
relatively minor.
VOFDM involves two basic techniques that backers said will
allow network operators to achieve high levels of market coverage with enough bandwidth
per user to support everything from voice to high-definition TV. This is a tall order,
given the fact that operators only have approximately 200 megahertz of spectrum to work
with.
The vector part of the nomenclature refers to the fact that
the system uses spatial diversity. That means it uses a dual-feed antenna receiver at the
end-user premises to capture signals coming in from separate paths and combines them to
maximize the signal-to-noise ratio at any given frequency.
This helps to strengthen the signals bouncing off
reflective surfaces, reaching users that are not in direct line of sight of the
transmitter, Lindenfelser noted.
Spectral efficiency -- which maximizes the number of bits
per hertz, or cycle of frequency -- is achieved through the orthoganal frequency-division
multiplexing aspect of the technology, where the number of bits inserted into thin slices
of frequency, or "frequency bins," depends on the noise-tolerance level within
each frequency segment.
"We pack a lot of carriers into the spectrum and
weight them based on signal-to-noise [ratio], which gets away from the modulation-capacity
limitations you encounter when you use a single carrier over a 6-MHz channel," Smith
said.
The result is a system that delivers 20 megabits per second
in a 6-MHz channel to all users, wherever they happen to be, Broadcom product-line manager
Pete LaRocca said.
Moreover, the chip, operating at baseband, can apply the
modulation technique to a signal that's destined to go out at virtually any
frequency, whether it's at the 1.9-gigahertz level of PCS (personal-communications
services) or at the 28-GHz level of LMDS (local multipoint distribution service).
But it's MMDS -- and specifically the high-volume
demand anticipated from a combined MCI and Sprint -- that comprises the immediate targets
for the development activities of the new alliance.
"We think this technology is what Sprint and WorldCom
need to be successful as providers of broadband services over fixed-wireless local-access
networks," Smith said.
Other players signing on with the initiative include
Motorola Inc., Texas Instruments Inc., Samsung Telecommunications America Inc., Toshiba
America Consumer Products, Pace Micro Technology plc, Bechtel Telecommunications, LCC
International, Electronic Data Systems Corp. and KPMG International.
So far, the only player involved that will be supplying
headend equipment is Cisco, but Smith said it appeared that other systems suppliers would
soon join, since Broadcom and TI will be making their chips available to Cisco's
competitors.
