Smart antennas, if they work half as well and deliver half the benefits vendors
claim, could be the making of Wi-Fi in the next phase of the industry’s evolution.
The popular vision for that next phase is ubiquitous Wi-Fi coverage, indoors
and out, public and private. However, given the range, coverage and capacity
characteristics of existing technology, it will be difficult to build business
cases for realizing it — no matter how low access point prices go.
With proliferation of Wi-Fi systems will come overcrowding and interference
in the unlicensed bands 802.11 uses. This will make it difficult for service
providers and network managers to maintain performance and service levels without
adding more and more access points.
Smart antennas may be at least part of the solution.
By increasing the range of Wi-Fi systems and reducing interference between
networks and within networks, smart antennas promise to reduce the number of
access points needed for a given coverage area and capacity – changing the economics
of deployment.
We talked recently to two purveyors of smart antenna technology.
Vivato uses its phased array antenna technology
in finished Wi-Fi infrastructure products. They include a Wi-Fi Bridge/Router
and a Wi-Fi Switch that integrates multiple access points, patented controller
technology and a 128-element antenna array.
The switch has been on the market since last spring and has already been deployed
by over 50 customers, mostly in large outdoor networks.
Motia is a fabless semiconductor company with
chip-level adaptive antenna array technology. The company claims its sub-$10
Javelin "applique" product can be added to existing access point and
Wi-Fi network interface card designs without significant re-engineering.
It could also be used to build after-market plug-in antenna products for Wi-Fi
access points.
Motia expects to have samples of the chipset by February and be shipping in
volume before the end of the second quarter of 2004. Motorola <QUOTE NYSE:MOT>
has already announced it plans to incorporate the Javelin product in future
wireless broadband products.
Phased or adaptive array antennas of the kind used by both Vivato and Motia
have been employed in radar since World War II and are also used in cellular
networks. The technology aims radio signals in a long narrow beam at a specific
receiver, in this case the Wi-Fi client.
It does this through electronic movement of the entire array structure, without
moving any mechanical parts. In a process Vivato calls PacketSteering, its products
do it on a packet-by-packet basis.
Because the beams are so narrow, they are less visible to radiating interference.
They are also only powered when needed — when a packet is being sent in a given
direction — which further reduces the likelihood of interference.
Vivato CEO Donald Stalter says deploying his company’s antenna technology typically
reduces the requirement for access points to cover a given area by a factor
of 3:1.
"In hotels where we use the bridge-router, what we’re finding is that
on a typical floor with thirty rooms, we’re essentially able to provide coverage
with one access point versus three of a well known competitor’s," Stalter
says. The Vivato products are also less expensive than some conventional access
points, he notes.
In outdoor settings, where the switch technology makes most sense, the performance
improvement is even more dramatic, increasing range from hundreds of meters
to kilometers. It also provides more even coverage with fewer dead spots.
In a somewhat artificial test, in an open flat area, the phased array antenna
was able to increase the coverage area over a conventional omni-directional
antenna from 20 million to 119 million square meters, Stalter says.
The economic benefit Vivato claims for the switch in particular comes partly
from the efficiencies of putting multiple access points in one array.
In the case of a cargo port of over four million square feet, the customer
came down to a choice between a single tower with a Vivato switch or 19 towers
with conventional access points.
"The difference in cost was $692,000 versus $92,000 with our [product],"
says Stalter. "And most of that $92,000 was the tower for the infrastructure."
Motia claims similar benefits for products based on its technology. Integrating
the Motia technology into just the access point in a network increases gain
by 13 decibels (dB), the company says. Using it in both access point and client
device increases gain by 18 dB.
"That translates into a two- to three-times increase in range or a three-
to four-times increase in range," says Motia’s chief scientist Jack Winters.
The Motia technology also helps mitigate multipath fading — loss of signal
strength due to interference within a network — and it reduces the transmit
power required, especially on the client side.
"And that reduces interference into other systems and makes systems work
better together," Winters explains
The pay-off, he says, is improved return on investment for enterprises building
Wi-Fi WLANs. Smart antenna technology will reduce their total cost of ownership.
"You’re looking in some cases at a four-fold reduction in the number of
access points required for the same coverage — or for better coverage,"
Winters says.
"But it’s much more than just the cost of the access point equipment itself.
You’ve also got to pull the wire — Ethernet and also power — to each of those
access points. Plus there are issues of management."
Motia sees applications for its technology across most Wi-Fi markets. It expects
the Javelin chipset will be built into antennas that could be plugged into antenna
ports on existing home or enterprise access points.
Winters says retailers experience a 30-percent return rate on access points
purchased for home and home office use, mostly due to poor performance resulting
from wireless propagation anomalies.
"A vendor can sell an access point with an antenna port. The consumer
buys that box and uses it, and if it works well, great. If not, instead of the
consumer taking the access point back, [the vendor] can say, ‘Here’s a smart
antenna that plugs into this access point [and fixes the problem.]’"
Motia sees the market for its product developing in three phases. First, manufacturers
building it into after-market products, then into access points, and finally
into network access cards.
"We foresee a great need for access point vendors to differentiate themselves
in the marketplace," says VP sales and marketing Robert Warner. "And
we see adding our technology as a very good way for them to do that."
"While we’re not counting on it, it’s quite possible smart antenna technology
will be prevalent in many if not all access points in future – not next year
perhaps, but in a couple of years."
The Motia chipset — smart antenna technology in general — has applications
outside Wi-Fi as well, including in GPS (Global Positioning System) and cellular.
"What Motia does is try to enable smart antennas in a wide array of systems,
but we don’t build systems," explains Winters.
Wi-Fi is the main focus for now, though. While Motorola is the only manufacturer
committed to using the technology so far, Warner claims the company has already
seen "a lot of interest."
"We see a lot of interest from consumer-oriented equipment vendors for
the add-on devices – the accessory market is not as price-competitive as the
access point market itself," he notes.
"On the other hand, many of the enterprise-oriented vendors like the fact
that the technology can improve the level of service [in WLANs]."
Can smart antenna technology deliver on all this promise? Stay tuned.
The technology will get even better, though, these vendors say. Vivato will
have a switch product later this year designed for indoor use that will deliver
the same kind of performance benefits as the first-generation product offers
in outdoor deployments.
Motia says chipset prices will come down and its products will get smaller
— though it already fits with no problem in PCMCIA and mini-PCI-format cards.
Motia and Vivato, meanwhile, are just two players in this space. Others include
Bandspeed, which designs access points incorporating
smart antennas, AirGo Networks,
which has chip products and zeeWAVES Systems,
which builds smart antenna products.
