Put a cell tower in the hallway
- By Joab Jackson
- Jul 25, 2005
Stately stone-and-steel edifices are not usually known for
hospitable wireless phone coverage. Yet visitors to some of the Library of
Congress buildings in
might be surprised to find that no matter how deep they burrow into the stacks,
they will still be able to get a strong signal on their cellular phones.
The library implanted antennas throughout its
buildings, as well as in the public tunnels connecting these buildings.
Visitors and staff enjoy full coverage throughout the facilities, not only from
the major cellular phone carriers but also for their BlackBerrys. Even police
officers and medical personnel get strong signals for their radios.
As citizens and government employees grow increasingly
reliant on wireless communications, agencies may find that it's beneficial to
install such in-house antennas.
'Ten years ago, did you really care if your cell phone
didn't work in a building? It was an annoyance, but people tolerated it. Not
so anymore. People expect phones to work everywhere now,' said Lance Wilson,
director of wireless research for technology market researchers ABI Research of
Oyster Bay, N.Y. Beyond convenience, in-building wireless coverage is
increasingly seen as essential. When firefighters and medical personnel rushed
during the events of <>
Year="2001" Day="11" Month="9">
Sept. 11, 2001
, they found their land radios did not work. The buildings' metal-and-glass
pillars blocked signals.
For more than a decade, a group of vendors have offered to
outfit buildings with wireless coverage, calling their mix of services and
technology 'in-building wireless.' They have focused on larger venues:
buildings with more than 500,000 square feet of floor space, tunnels and
enclosed structures such as shopping malls and underground facilities.
For such facilities, a wireless distribution system acts
much like such other utilities as a heat, ventilation and air conditioning, said
Ed Jungerman, senior vice president of marketing for InnerWireless Inc. of
. 'Whereas an HVAC system distributes heated and cooled air uniformly
throughout the building, [a] wireless distribution system distributes this full
range of radio signals through the building,' Jungerman said.
In addition to boosting cell phone signals, in-building
wireless systems can also provide the foundation for wireless local area
networks and even wireless office phones. WiFi LANs, for instance, run well on
such in-building networks. Although organizations are just starting to look at
this capability, such flexibility may shake up IT architectures in the decades
For the Library of Congress, setting up an in-building
wireless system made good business sense. Congressional researchers and members
of Congress themselves frequent the buildings, and often expressed the desire
for greater cellular coverage, said Mike Handy, chief of the multimedia group
for the Library of Congress' information technology services office.
Especially during emergency evacuations of Capitol Hill offices'more frequent
of late'such connections are vital. Feds need their cell phones and
BlackBerrys to know where to reconvene.
Useful for employees
Stronger cellular signals would also benefit the
library's own employees, Handy said. Many participate in projects that involve
moving about the library, or meeting in different places. As a result, they
often can contact each other only via their wireless phones or pagers.
The buildings themselves are what blocks signals from the
carriers' cell towers. They are largely composed of granite and concrete, as
well as metal partitions that divide up larger rooms, all of which play havoc
The Library of Congress contracted with EMS Wireless for
$2.9 million to install the necessary equipment to blanket its entire four
million square feet of space with wireless coverage.
, a division of Atlanta-based hardware manufacturer EMS Technologies Inc.,
completed the installation last December and is in the process now of adding
Although approaches vary from vendor to vendor, the basic
architecture of an in-building wireless system such as the Library of
Congress' is pretty simple. Conceptually, it is much like one big antenna,
shaped like a tree, with branches on each floor of a building. Carrier cellular
signals are collected from a base or relay station outside the building and are
relayed to a central unit, often called a head end, located in the basement or a
telecom closet. From the head end, transmissions are conveyed to each floor over
copper or, for large installations, fiber-optic cables.
Each floor has a cable tap or hub for tapping into the
transmission line. Signals are then distributed further through a cable that
stretches around the floor. The cable, known as leaky coax or radiating cable,
itself can act as an antenna, sending and receiving signals from wireless
devices. For even greater coverage, a vendor could provide additional antennas
in strategic locations.
Originally, in-building wireless providers worked mostly on
behalf of cellular telephone carriers. Agencies that signed enterprise
agreements with wireless carriers could require in-building coverage, said Shawn
Thompson, president of In Building Wireless Inc. of
Thompson's company worked on behalf of Sprint Corp. of
, to provide coverage for the
headquarters of the Environmental Protection Agency, as well as for the
Agriculture Department buildings in
In recent years, however, building owners started
installing such systems themselves. 'You'll see end-users fund their own
projects so they are not only limited to Sprint or Verizon,' Thompson said.
The good thing about in-building wireless antennae is that
they can work with a wide range of frequencies, from around 400 MHz up to 3.5
GHz. Most of today's cellular carriers use frequencies around 1.9 GHz. Pager
and first-responder frequencies usually fall into the 800 to 900 MHz range. To
sort out the signals and pass them to the appropriate carrier, companies provide
filters, usually packaged in add-on modules placed within the head end unit. For
instance, MobileAccess Inc. of
, offers the MobileAccess-2000 system, which can support up to 20 wireless
'You can add or remove systems at any point in time,'
said Lou Martinage, director of marketing and business Development for
Hardware is only one part of an in-building wireless
implementation, however. Orchestrating the range of signals within a building
requires considerable engineering.
'Each of the materials used in the construction of a
building has unique RF characteristics,' Jungerman said. 'Drywall im- pedes
the signals in one way, granite in another. The radio signals react differently
in each of those cases.'
In order to boost coverage, an organization may have to add
additional repeaters or base stations. And as an organization adds new services
or increases the range of coverage, it must factor in interference and power
For new customers, most vendors or integrators will create
an RF map of the facility, using simulation software such as RD Manager from
Wireless Valley Communications Inc. of
. This software will allow a detailed view of the areas to be covered.
Not only must offices, cubicles and conference rooms have
access, but also areas such as bathrooms, hallways, elevators and stairwells.
New wave of uses
Like any new technology worth its salt, in-building
wireless can not only address old concerns, but also lay the groundwork for
entirely new capabilities. Getting cell phone coverage in buildings was the
original concern, but once in place, an in-building system can also be used for
such additional services as wireless office phones and networks. Although the
business case for these uses is far from proven, they are worth considering.
For instance, once a network is installed, why not replace
the phone on the worker's desk with a cellular unit that can be taken
anywhere? This might be particularly valuable to organizations with workers who
move around a lot, said Phillip Redman, research vice president of mobile and
wireless IT research company Gartner Inc. of
Right now, monthly cellular phone bills would prevent the
enterprise from untethering its workers, but that may not always be the case,
Redman said. If carriers can reduce the cost of in-office calls from 10 or 12
cents a minute to the level of landline rates'usually less than a penny per
minute'they may find more customers. Cellular carriers would also have to work
at creating voice mail systems that can work in much the same way office voice
Some wireless companies seem to be heading in this
direction. 'No one has put together a full package yet, but we're seeing the
elements come together,' Redman said.
For many, WiFi is the next frontier for in-building
wireless. With the proper filters, WiFi's 2.4 GHz fits easily within most
in-building wireless setups. Instead of running separate cables through a
building for a local area network, why not just set up a wireless network? And
why not use the same infrastructure you used for the in-building cellular
The National Institutes of Health took this route.
Dedicated last fall, NIH's
is an 870,000-square-foot conglomeration of inpatient units, day facilities and
research labs located at NIH's main facility in
The center installed the InnerWireless platform to handle not only cellular and
first-responder calls but also WiFi connections.
Most industry observers agree that running WiFi over an
in-building wireless system is more expensive than setting up a separate WiFi
network. A typical in-building wireless implementation usually ranges from $1 to
$4 per square foot, while a large building could be outfitted with WiFi at about
$1 per square foot.
Still, there are good reasons for consolidating the
networks. According to Redman, the advantage of placing all the communications
on one infrastructure is simplicity. Organizations today 'are standardizing
the wireless networking that they have,' he said.
Another advantage of using a unified network to carry WiFi
traffic is that it offers more uniform coverage than dedicated WiFi networks,
Thompson said. 'With access points, you will have hot spots, where you may
have good connectivity in one place, but walk over two offices and the data rate
gets cut,' Thompson said. The in-building wireless approach 'will have a
more consistent coverage.'
With WiFi in place, an enterprise may also take advantage
of newly emerging voice over wireless local area network, or VoWLAN, phones.
Nortel Networks Corp. of
, recently demonstrated mobile phones that can automatically jump from cellular
signals to WiFi signals, according to Richard Gorman, lead wireless architect in
the federal space for Nortel. Using such a phone, an employee could use WiFi for
intra-office communications, which would compete with current landline rates,
and then switch to cellular coverage when leaving the premise.
As of yet, very little has been done to enact standards for
in-building wireless equipment. While cables and antennae are fairly
interchangeable, each company's head end units and hubs are unique.
Fiber-optic-based systems in particular rely on incompatible vendor-specific
equipment. Once agencies invest in one company's system, they may be locked
into buying replacement parts and upgrades from that company.
Most analysts and vendors insist that this is not a
problem. 'All these folks are doing is delivering the signal,'
said. 'They have pretty simple systems, so it is not like there is a whole
lot that can go wrong with the elements in the back end.'
'We leave [standards] to the end-to-end protocols,'
said Lou Martinage director of marketing and business development for
MobileAccess. 'A WiFi implementation will have a standards-compliant access
point on one end and a standards-compliant client on the other, and everything
Overall, analysts see in-building wireless as a technology
that can accommodate changes in wireless networking.
'These networks that we're installing are rapidly
becoming a common utility,' Thompson said. 'Regardless of what eventually
will happen, in-building wireless will be a common infrastructure. It will be
available for just about any technology that will come about.' n