In Defense Of Paging Over Wi-Fi Networks
Ver 0.2 November 29, 2008
In early November, I delivered a presentation to the Paging Technical Committee outlining the current status of technology that would provide on-site paging service over existing Wi-Fi networks.
Subsequent to that presentation, I have received a number of comments regarding the pros and cons of paging over Wi-Fi networks rather than 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 Wi-Fi 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 Wi-Fi paging. Even at this preliminary stage, however, several things, can be affirmed:
| || 1.|| Multiple applications are now operating on Wi-Fi networks in many medical institutions, apparently without undue inter-application interference. Furthermore, the IEEE has recently updated the standards that govern Wi-Fi systems to a standard known as 802.11n. This newer standard includes a “good neighbor” protocol that will further reduce the potential for interference. Notwithstanding these factors, the protocol designed for Wi-Fi 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-powered 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.
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 equipment.|
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 (Swissphone) 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 disadvantages:
| || 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 service provider.|
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 Wi-Fi 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 Wi-Fi 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, Wi-Fi networks do have an attractive potential for additional functionalities:
| || 1.|| The smaller coverage zones provided by multiple Wi-Fi 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 medical equipment.|
| || 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 Wi-Fi 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, Wi-Fi 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 two-way technology. Appropriate cost reduction, however, is most probably not within reach.|
| || 2.|| The paging industry, manufacturers and carriers, can embrace the migration to Wi-Fi 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 Wi-Fi 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. Through cooperative ventures involving both carriers and manufacturers, 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.
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 e-mail, 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.
1 Communication in Critical Care Environments: Mobile Telephones Improve Patient Care, Roy G. Soto, MD, Larry F. Chu, MD, MS, Julian M. Goldman, MD, J. Rampil, MD, and Keith J. Ruskin, MD, Anesthesia & Analgesia 2006;102:535-541 © 2006
2 Intensive care unit alarm repeater and ECG viewer on a Wi-Fi-enabled personal digital assistant, Maarek, V.; Lamberti, C.; de Bie, J.; Rangoni, F.; Pirini, G. Computers in Cardiology, 2004
3 Call for Re-evaluation of Mobile Phones in Hospitals, Simon Lam Canadian Journal of Anesthesia 49:632-633 (2002) Toronto, Ontario