In Defense Of Paging Over WiFi NetworksDocument Transcript
In Defense Of Paging Over WiFi Networks
Ver 0.2 November 29, 2008
In early November, I made a presentation to the Paging Technical Committee outlining the
current state of development of technology that would provide on-site paging service over
existing WiFi networks.
Subsequent to that presentation, I have received a number of comments regarding the pros and
cons of paging over WiFi networks compared to conventional paging channels, particularly in
the hospital environment.
These commentators have raised important questions that can be summarized as follows:
1) Potential interference to or from other WiFi applications.
2) The advantage of keeping hospital paging systems independent from other technologies
(such as telephone PBX, data network, or even radio or microwave)
3) The unique requirements of multi-facility hospital clusters that are spread over a 5 or 6
square mile area and, therefore, require very large radio coverage areas (for example, the
Cleveland Clinic, NY Presbyterian Hospital)
Each of these concerns highlights a need for in-depth evaluation and, potentially, the
introduction of particular design criterion for WiFi paging. Even at this preliminary stage,
however, several things, can be affirmed:
1. Multiple applications are now operating on WiFi networks in many medical institutions,
apparently without undue inter-application interference. Furthermore, the IEEE has
recently updated the standards that govern WiFi systems to a standard known as 802:11
N. This newer standard includes a “good neighbor” protocol that will further reduce the
potential for interference. Notwithstanding these factors, the protocol designed for WiFi
paging must take the potential for interference into account.
2. It is true that independence from other systems can sometimes be advantageous, but most
paging systems today are already interfaced to PABX or LAN Networks in order to
provide message input access. Many also use telephone cable facilities to link control
terminals with base stations.
3. While multi-location institutions with very large geographic coverage areas are almost
certainly still better served by classical high-power paging facilities, many more
institutions require paging coverage in a single building, or even in only a portion of a
building. For these the advantage of wide-area coverage is less compelling.
Paradoxically, while paging has provided valued service into the Health Care community for
more than 45 years, there are growing concerns within that community, as expressed by articles
in medical publications including the New England Medical Journal, that paging is no longer
fully adequate and that consideration should be given to allowing the use of cellular phones as a
communication tool in hospitals. i
Many hospitals currently use either private (on-site) one-way paging, or carrier provided one-
way paging, and most of the concerns expressed were related to increased delay that is generally
attributed to the lack of “message received acknowledgement” in one-way paging. Even when
radio coverage in a hospital is excellent, which it often is in both private and carrier systems,
delays can occur because of the lack of knowledge regarding the ability of a paged individual to
respond to the page, even if there is a very high probability that the page was received. Most
importantly, these delays are perceived by many health care professionals as constituting an
increased risk to patients. Two-way systems, including cell phones and ReFLEX paging, afford
confirmation, not only that messages have been received, but also that the paged individual is
able to respond as required by the circumstances and are thus increasingly desirable.
WHY NOT ALLOW CELL PHONES?
Because they can be leased from cellular carriers with absolutely no infrastructure costs to the
hospital, coupled with the fact that most medical professionals and staff already carry cell
phones, cell phone are a very attractive solution to hospital communications challenges. For a
number of years, however, fear that cell phone transmissions could interfere with medical
equipment was cited as a primary reason for the widespread ban against cell phone use in patient
care areas of hospitals.
A secondary reason cited was the “patient annoyance factor” if members of the general public
(patients, visitors etc.), in addition to medical staff, were allowed to use cell phones. (Consider
the annoyance now so common in restaurants, trains and even churches and synagogues).
Virtually no empirical evidence exists to support the fear of “interference” and, over the last
several years, the ban on cell phones due to interference concerns has been reduced considerably.
Accordingly, a number of hospitals have begun to allow cell phone use by medical staff and
some even permit patients and visitors to use cell phones in specific areas of the hospital. The
ban based on patient annoyance, however, continues to be a large deterrent to a large-scale move
to cell phones in hospitals. A number of hospital administrators now ask: “If we allow the staff to
use cell phones, how can we deny use by visitors and patients?”
SO WHY NOT UPGRADE TO ReFLEX TWO-WAY PAGING?
From functionality and reliability points of view, ReFLEX two-way paging offers an almost ideal
solution to the communications needs of the hospital community. Of particular interest, is the fact
that quality ReFLEX pagers are today available from several manufacturers. The major
impediments to a large scale migration to ReFLEX appears to revolve around two issues:
1. Difficulty in obtaining RF spectrum allocations,
2. The high cost of ReFLEX infrastructure equipment, particularly radio base station
Although doing so requires considerable effort and time, the spectrum issues can be resolved and
spectrum allocations can be obtained.
The infrastructure cost issue, however, is much more challenging. Several recent system
proposals have resulted in non-redundant infrastructure price quotations of greater than
$100,000. While such a price tag may be considered reasonable for a very large institution
requiring hundreds or even thousands of pagers, it becomes prohibitive for smaller hospitals,
many of which require only several dozen pagers.
ARE THERE OTHER OPTIONS?
A European manufacturer (Swiisphone) has recently introduced a pager that combines standard
POCSAG outbound signaling (toward the pager) with a GSM cellular signaling in the return path
to provide paging “message received” confirmation.
This approach solves the major shortcoming of one-way paging, but it suffers several
1. GSM coverage may not be available at many hospital in-building locations and the cost
and complexity of adding cellular repeaters is considerable.
2. Continuous cooperation would be between the paging provider and the GSM cellular
THE HOSPITAL PERSPECTIVE
Many of the hospital administrators responsible for purchasing facilities such as paging today are
IT specialists whose main experience is with data facilities including WiFi networks with which
they are very comfortable. Such administrators have difficulty justifying the purchase of a
$100,000 network dedicated to paging when, in their view, the hospital already owns a WiFi
network covering the hospital areas that need paging coverage.
“Just give us a pager that runs on our existing 802:11 network” is a frequently heard refrain. And
it’s a difficult request to ignore.
In addition to cost considerations, and in spite of the need to overcome technical obstacles, WiFi
networks do have an attractive potential for additional functionalities:
1. The smaller coverage zones provided by multiple WiFi Access Points permit pager
location to be determined with reasonable resolution (± 200 feet in many cases). In
emergency situations, it can be advantageous to quickly ascertain the approximate
location of key personnel. This information can permit group messages to be location
specific (e.g. all surgeons on 3rd floor, wing D).
2. Location data could also permit pagers to be placed in a “receive only” mode, with
transmitters turned off, in areas with increased concern regarding interference with
3. Location data could also support staff initiated emergency assistance calls. (Man Down).
Such capabilities are important in certain types of facilities and under certain conditions.
4. The wide bandwidth available in WiFi could permit a variety of medical information,
such as patient records, to be sent directly to medical staffs’ pagers.
5. The nature of 802:11 networks simplifies the addition of low cost coverage expansion or
fill-in repeaters when required.
6. Because they almost always use multiple, independent “Access Points” (repeaters) to
cover a desired area, WiFi networks generally exhibit some level of inherent redundancy.
7. Location data could also support an Asset Tracking service that would allow administrators to
determine the location of pieces of portable equipment at any moment in time.
For the stated reasons, demand for two-way wireless communications can be expected to grow
within the hospital community over coming months. This demand can be met in several ways:
1. Significant ReFLEX infrastructure cost reduction can be achieved to allow the paging
industry, carriers and manufacturers, to continue to compete in their traditional hospital
market Using ReFLEX tw0-way technology. Appropriate cost reduction, however, is
most probably not within reach.
2. The paging industry, manufacturers and carriers, can embrace the migration to WiFi
technology, in which case those carriers and manufacturers who make the shift can
continue to compete in the hospital market.
3. Manufacturers could develop a hybrid pager that combines WiFi and traditional
FLEX/POCSAG technology that would also allow both pager manufacturers and carriers
to continue to enjoy the hospital market.
4. Hospitals will more fully embrace cellular, in which case no part of the paging industry,
carriers or manufacturers, will play any role whatsoever.
In this light, we would urge the paging industry, carriers and manufacturers, to approach this
emerging technology in a creative spirit. Recent history has shown that the spontaneous
rejection of competitive new technologies can be counterproductive. Keep in mind that when
the cellular industry first introduced text messaging, many paging “experts” counseled that it
would never work! Today, how many dollars does text messaging generate for the cellular
operators? Similarly, when Research In Motion first introduced the Blackberry to support
mobile email, our industry declined to compete fearing excessive traffic and clogged
channels! Who today would not like to be sharing in RIM’s success?
Rather than repeat past shortsightedness, we urge cooperation between carriers, hospital
customers and manufacturers, so that the hospital market, truly the cradle of the paging
industry, can be introduced to new levels of performance and functionality that benefit both
the medical community, patients and the paging industry.