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 buildin
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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 ventilators1 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 building4
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
Monitoring Devices”, Mayo Clinic Proceedings, v76, 1/01.
For patient safety, the use of cellular phones is not permitted while inside hospital buildings.
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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 device5 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
Trang 4Web Site: www.adc.com
From North America, Call Toll Free: 1-800-366-3891 • Outside of North America: +1-952-938-8080 Fax: +1-952-917-3237 • For a listing of ADC’s global sales office locations, please refer to our Web site.
ADC Telecommunications, Inc., P.O Box 1101, Minneapolis, Minnesota USA 55440-1101 Specifications published here are current as of the date of publication of this document Because we are continuously improving our products, ADC reserves the right to change specifications without prior notice At any time, you may verify product specifications by contacting our headquarters office in Minneapolis ADC Telecommunications, Inc views its patent portfolio as an important corporate asset and vigorously enforces its patents Products or features contained herein may be covered by one or more U.S or foreign patents An Equal Opportunity Employer
103148AE 7/06 Revision © 2006 ADC Telecommunications, Inc All Rights Reserved
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
your cell phones in this facility.