Tài liệu Digivance® ICS For Healthcare Applications ppt

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Digivance
®
ICS
For Healthcare Applications
Digivance
®
ICS
For Healthcare Applications
Wireless in Hospitals – Good or Bad?
As you enter most hospitals, it is very likely that you will be greeted with a sign
looking something like this:
Studies have shown that radiation from cell phones has the potential to interfere
with cardiopulmonary monitoring devices, and in some cases may even cause
malfunction of patient ventilators
1
. Such evidence would seem to indicate that
cell phones constitute a significant risk to patient health and safety, warranting
their ban from hospital facilities. But many of the same hospitals that are
banning cell phones are, at the same time, bringing more and more wireless
equipment into the hospital environment. Wireless Local Area Networks (LANs)
are being installed at a rapid rate. The mobile access to medical records provided
by wireless LANs is being touted for its benefits to patients, in articles with titles
such as: “Wireless LANs: Just What the Doctor Ordered”
2
and “Wireless Is the
Healthy Choice”
3
. In addition to network access at the nurse’s station, such
wireless systems often include mobile voice handset coverage throughout
the building

4
.
What is the Difference?
So why are wireless LANs being installed at the same time cell phones are being
banned? Why can't I use my cell phone when I see hospital personnel roaming
the corridors talking on theirs?
It’s all a matter of POWER. With wireless LANs and local wireless phone systems,
fixed antennas are distributed throughout the building. The distance from a
laptop computer or wireless handset to the nearest antenna may be only a
hundred feet or less. Such distances can easily be spanned with transmit powers
of 20 milliWatts (mW) or less.
1
Tri, Jeffrey L., David L. Hayes, and Rodney P. Severson. “Cellular Phone Interference With External Cardiopulmonary
Monitoring Devices”, Mayo Clinic Proceedings, v76, 1/01.
2
Robinson, Teri. “Wireless LANs: Just What the Doctor Ordered”, InternetWeek, 8/24/98.
3
Schick, Shane. “Wireless Is the Healthy Choice”, Computing Canada, 12/1/01.
4
Lee, Chris. “The Wireless Cure”, ZDNet (UK), 9/24/01.
For patient safety, the use of cellular phones is
not permitted while inside hospital buildings.
Page 3
Digivance™ ICS For Healthcare Applications
In contrast, a typical cell phone not only has to reach
a cell site antenna that may be located a mile or more
away, it must first penetrate the steel and concrete shell
of the building itself. In order to do this it will likely need
to operate at its maximum power level, typically 600
mW. In fact, even though cell phones have the ability to

reduce their power in good coverage areas, most studies
on the effects of cell phone interference assume that
within hospital buildings, the cell phone will generally
be operating at its maximum rated power.
At the maximum cell phone power of 600 mW,
the Mayo study found that “clinically important”
interference occurred 7.4% of the time if the phone
was within 60 inches of a piece of medical electronics.
Actual equipment failure occurred only with one piece
of tested equipment, and this occurred only when
the 600 mW cell phone was placed within 5-10 cm
of a data port on the rear panel of the device
5
. While
this may seem like a minimal threat, the healthcare
environment mandates erring on the side of safety;
hence, the ban on cell phones.
At 20 mW, however, the radius of potential interference
is reduced from 60 inches to about 11 inches; and the
risk of an equipment failure, such as the one noted in
this study, becomes almost non-existent. This reduces
the risk significantly enough for such low power wireless
systems to be considered “hospital safe”.
Problems with Cell Phone Bans
There are several difficulties with the widely adopted
ban on the use of cell phones in hospitals. One big
disadvantage of this policy is that it deprives medical
workers, as well as patients and their families, of a
primary means of communication–in fact the very
means of communication that may not only be

the most convenient but also the most vital in
emergency situations.
A second disadvantage is that such a ban requires
enforcement. Cell phone use has become prevalent to
the point that many people no longer give a second
thought as to where they are when they place or take
a cell phone call. The aura of acceptability is even
further enhanced if visitors see hospital personnel using
cell phone-like handsets, not knowing that they may
be non-standard units designed for use only with the
hospital's internal wireless phone system.
The third disadvantage is that such bans are ineffective.
Many people do not realize that even when not being
used in conversation, cell phones (unless they are
completely turned off) continually transmit control
information to maintain contact with the nearby base
stations. As long as they do not use their phones, most
people believe they are complying with the ban. In
reality, many hospitals which have instituted such a ban
are likely frequented by visitors whose cell phones are
continually transmitting signals from within their pockets
or purses.
Problems with Local Wireless
Phone Systems
Installing a local wireless phone system gives hospital
personnel cordless access at low power. However, this
solution is not without its own drawbacks. The local
system may require use of special handsets which are
not compatible with standard cell phones. This means
that hospital personnel need to carry two mobile

phones, one for use inside and one for outside the
building. Such local systems can be expensive and
difficult to integrate with the existing PBX. Handsets,
in particular, tend to be more expensive, as they do
not benefit from the quantity distribution and service
provider subsidies that keep cell phone prices low.
In addition, a local wireless phone system provides
access for hospital personnel only, not for hospital
visitors. It also does nothing to solve the problem of
energy being transmitted continually by idle (but still
turned on) phones in pockets and purses.
The Digivance
™
Solution
The Digivance
™
Indoor Coverage Solution (ICS)
enables employees and visitors to use their cell phones
within hospital buildings while minimizing the risk
of interference to medical equipment. It does this by
distributing cell phone coverage throughout the building
through a series of low power Digital Remote Units
(DRUs), each transmitting a maximum of +13 dBm
(20 mW) of power.
Placing low power DRUs throughout the building means
that cell phones will only have to transmit as far as an
antenna which is, at most, a few hundred feet rather
than miles away. In addition, its signals do not need to
penetrate through the steel outer frame of the building.
This means that cell phones used within the building

no longer need to operate at maximum power. Instead,
the power control algorithm inherent in all cell phone
systems will reduce the cell phone power to typically
tens of milliWatts or less.
The reduction in power takes place automatically,
without any action required by the cell phone user.
Even the phones forgotten in pockets and purses will
automatically reduce their power simply by being in the
vicinity of a Digivance DRU. As an added benefit, this
reduced power results in lower current drain, thereby
maximizing battery life, at the same time interference is
being minimized.
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Targeted Coverage
By careful placement of the remote units,
wireless coverage can be customized to meet
the requirements of any facility. Coverage can
be added to difficult areas, such as basements,
tunnels, and shielded rooms, by installing DRUs in
those locations. In addition, antenna placement

can be used to independently control the amount
of power reduction in different sections of the
building. Sparsely placed antennas will result in
a wider range of handset powers, which may
be acceptable in public areas of the building;
more closely spaced antennas will provide tighter
power control in particularly sensitive areas, such
as critical care units.
The Digivance Advantage
Digivance ICS uses advanced technology that
sets it apart from all other indoor coverage
systems. It is the only such system that
distributes its wireless coverage over digital
fiber. Fiber, unlike coax or twisted pair wiring, is
completely immune to reception or generation
of electromagnetic interference, making it easy
to install alongside other wiring without fear
of noise or crosstalk. Digital optics means that
either single or multimode fiber can be used
without degrading signal quality, allowing the
installer to take advantage of any unused fiber
that may already be in place within the building.
Digital fiber also minimizes the noise level on
the path back to the base station. Keeping
the noise level on this path low is essential to
minimizing cell phone output power, and only
the digital optics of the Digivance system can
offer the lowest possible noise level, regardless
of the length of fiber. Digital optics also enables
complete flexibility of installation topology and

number of antennas. Coverage areas can be
expanded by adding, or even daisy-chaining,
Digital Expansion Units (DEUs). Multiple areas,
floors, or even multiple buildings can be covered,
with uniform “digital quality” signals delivered
to even the most remote antenna.
Summary: The Benefits of
Installing a Digivance ICS
Hospital System
• Potential for interference with hospital
equipment is minimized, or even eliminated,
by minimizing handset transmit power.
• The need to enforce a cell phone ban

is eliminated.
• Power reduction applies to all phones, even
those “forgotten” in pockets and purses.
• Hospital employees are given the convenience
of maintaining mobile communications,
without requiring separate handsets for
indoor and outdoor use.
• Hospital visitors are able to stay in
communication with others.
• Battery life for portables is increased.
• The digital fiber technology of Digivance
ensures optimum reliability, ease of
maintenance, and simplicity of installation

for trouble-free and worry-free service.
• Digital fiber technology guarantees immunity

from optical path loss. Every antenna in the
system, from the closest to the farthest, will
provide the same high quality signal–enabling
uniform coverage throughout the largest
buildings or even multi-building campuses.
In short, the need for safe, high quality, and
trouble-free wireless communications in the
hospital environment has been met with ADC’s
unique indoor coverage solution–the digital
advantage of Digivance.
This hospital is equipped with
Digivance
™
coverage. Feel free to use
your cell phones in this facility.