Wireless: What Works?
- By Wendy Chretien
The new ‘millimeter wave’ wireless technology may be outside
your comfort zone, but it’s out there and working well for some of your
Dartmouth's Millimeter wave installation:
'hiding' in Baker Tower.
Thinking beyond Wi-Fi (and no, this is not another hype of WiMAX), an emerging
option you should know about is very high frequency (71-76 GHz, 81-86 GHz, and
91-95 GHz), very high capacity licensed wireless. The technology is known as
millimeter wave or E-band, and the FCC also refers to it as “virtual fiber.”
At these recently-made-available frequencies, the overall bandwidth capacity
is much greater than traditional radio frequency communications, even microwave.
(Note for techies: The real difference is that licensees may use up to 5GHz
of frequency for both transmit and receive, equating to 10GHz total.) These
focused, line-of-sight, Gigabit/second signals can be set up in point-to-point
configurations for distances up to a mile. Sounds great, no?
So, What’s the Catch?
If you’re a skeptic, like I am, you’ll have noted several potential
caveats in the above description, namely “licensed,” “emerging,”
“line of sight,” “point to point” and “up to a
‘Licensed’ tells us that one must obtain
a permit from the FCC in order to use this type of system. (I can hear the groans
at this realization.) What may surprise you, though—especially if you’ve
ever struggled with these types of permits in the past—is that the process
for obtaining the permits for these frequencies has been moved online and is
now greatly streamlined: Now a license can be secured within days, not months.
The dreaded ‘emerging.’ From the customer’s
standpoint, this can mean buying into proprietary systems. Often, it means that
there are few vendors of the technology, thus limiting competition and ultimately
equating to high prices. These are real risks you will need to decide to take
or not; if you use this technology for selective purposes, however, the risks
may be moot.
‘Line of sight’ is probably the most
significant barrier to the use of millimeter wave technology, in that there
must be no physical barriers between the sites you plan to connect. Trees, for
instance, can be a significant barrier. You truly need to be able to stand at
point A and clearly see point B (and yes, it’s legitimate to use binoculars
or a telescope).
‘Point to point.’ Unlike most implementations
of Wi-Fi, E-band wireless d'esn’t blanket an area around the antenna,
but rather, shoots a highly directional, “pencil-beam” connection
to another antenna/receiver. That means this technology is best suited to direct
building-to-building connections, also known as point to point. The real advantage
of focusing the beam is that the traffic-carrying capacity increases by an enormous
amount: E-band can carry up to 2.7 Gigabits/second of information (this is the
claim; your mileage may vary). This is a previously unheard-of capacity for
wireless technology. Only Free Space Optics (which is light-based rather than
radio-frequency-based—and therefore also technically wireless) comes close.
We’ll cover that soon.
‘Up to a mile.’ The distance limitation
is a matter of physics. Radio frequency signals can travel only so far before
they are absorbed by the atmosphere. (In the wireless world, this phenomenon
is known as “attenuation.”) Every type of wireless signaling is
subject to this law of physics. Still, around a mile is sufficient for most
Even after all of the possible “gotchas,” this technology truly
has something to offer—namely, it can be an excellent substitute for a
relatively short run of fiber when a fiber installation would be extremely tricky,
time-consuming, or costly; or, it can act as a backup to an existing fiber link;
or, it can serve as an upgrade to an existing point-to-point wireless link that
has too little bandwidth for current and future needs. In short, d'esn’t
your campus have a need for this?
Who’s Using It?
One of the first companies to market in this new arena is GigaBeam Corp. (www.gigabeam.com),
which started business in 2004 and already boasts four higher education customers:
Boston University, Dartmouth College (NH),
Oklahoma State University, and the University of Maryland.
BU and OSU each have a building link used to transport medical files, including
radiographs (“x-rays” to most of us). Dartmouth and Maryland make
use of the large-capacity links for data communications between sites.
GigaBeam claims “reliable point-to-point two-way communications at up
to 2.7Gbps with 99.999 percent weather availability for about a mile or more”
and calls its product WiFiber. The products currently available provide up to
This skeptic needed some real-life input, so I conducted a reality check with
David Bucciero, the company’s director of Technical Services, and Kathy
Frazer, the manager of Technical Services at Dartmouth College. According to
Bucciero, “Dartmouth has a reputation as one of the most unwired campuses
in the nation and as being on the leading edge in technology, [thus] the use
of millimeter wave technology can be considered an extension of that.”
Dartmouth also happens to be in a location where installing fiber is problematic.
There’s too much granite to bury it cost-effectively, and the owners of
utility poles in that area set a high value on the use/leasing of that real
estate. So when the college determined it needed a high-capacity link to the
Dartmouth Hitchcock Medical Center (DHMC) and needed to get it up and running
quickly, Technical Services looked at a number of wireless alternatives. DHMC
had a leased ATM connection, and the backup to that was via satellite, which
could not provide sufficient bandwidth if the primary link failed. Due primarily
to the available data rate, the college selected the millimeter wave solution.
The initial installation of the system was up in just a few days. But after
a short time, the college was seeing loss in the link. GigaBeam sent technicians
who diagnosed the problem and stayed on site until it was corrected. Since that
first glitch, the system has been running smoothly and is now used as an always-on
system, which load-shares with the leased circuit. The satellite connection
has since been discontinued.
After that success, the college added another link between ISTS and the new
Rugby Clubhouse. In this case, the line of sight was somewhat marginal. The
GigaBeam technicians warned Dartmouth’s Technical Services that growth
of trees could be an issue, and it was. To resolve the problem, the college
recently increased the height of the pole on which one antenna is mounted. The
new link is now the only connection between the buildings and is functioning
as advertised. In fact, Dartmouth is running Cisco (www.cisco.com)
voice-over-IP (VoIP) phone traffic over this link. And Technical Services is
considering a third implementation.
At Dartmouth, the millimeter wave system had an ROI of less than eight months,
compared to fiber.
Is It Compatible With Current Wireless?
Because Wi-Fi and millimeter wave use completely different frequency ranges,
there’s no need to worry about interference between them. In fact, E-band
could become a backhaul facility for an otherwise isolated building in which
you’d like to install Wi-Fi but haven’t because there hasn’t
been a feasible way to connect it to the rest of the campus.
How Much Will It Set Us Back?
A single link between two sites costs about $50,000. If that number seems high,
compare it to the cost of burying new fiber along a mile-long route, which typically
starts at $75,000, but can be as high as $250,000 in an urban environment. (According
to Bucciero at Dartmouth, the millimeter wave system had an ROI of less than
eight months, compared to fiber.)
As is typical in the technology arena, you can anticipate that costs will decrease
as more manufacturers bring products to market. L'ea Corp. (www.l'eacom.com)—truly
a pioneer in the market since its inception in 2000—has a number of users,
including the Hawai‘i Institute of Marine Biology. Another vendor that
has announced, but as of this writing is not yet shipping millimeter wave products,
is BridgeWave Communications (www.bridgewave.com).
To sum up, if there’s a pressing need for high-capacity wireless on your
campus now, E-band/millimeter wave/“virtual fiber” may be the right
choice for you.