Full speed ahead for wireless LAN technology at HIMSS ’99
By ARTHUR GASCH
Healthcare InfoTech Contributing Editor
ATLANTA The annual Healthcare Information and Management Systems Society (HIMSS; Chicago) conference is always a showcase for new and enhanced technologies, and the gathering at Atlanta’s World Congress Center last week was no different, except that the pace of enhancement is accelerating. That was especially true for wireless LAN (local area network) technology, which has been an area of increasing interest over the past three years.
The technologies and solutions available in the wireless LAN sector have dramatically increased and changed. In the early days (three years ago) of spread spectrum (SS) wireless, there were data rates of approximately 300 kbits/second (at least in the 902-928 MHz bands). Today, with the IEEE 802.11 Wireless Ethernet specification and additional refinement, most of the significant players have opted for the 2.4 GHz band, and offer 2 Mbit/sec. data rates, using either "direct sequence" or "frequency-hopping" approaches. Indeed, more innovative companies like Breezecom (an Israel Tank Command spin-off technology) have achieved 3 Mbps at 2.4 Ghz with their 32 frequency hopping spread spectrum technology.
Developments previously announced at HIMSS by Aironet and RadioLan push the data rates at 2.4 GHz. to 11 Mbits/sec. and 10 Mbits/sec. using direct sequencing approaches. Harris Semiconductor’s PRISM radio chips are an important element in a new series of 11 megabits-per-second (Mbps) wireless local area network (WLAN) and wireless bridge solutions announced at HIMSS by Aironet because Harris is the only source of the chip, and both vendors who have announced more than 2 Mbps depend upon this same chip, as will everyone else who chooses to implement higher speeds.
Beyond that, there new developments require a caveat or two. While these higher data rates can be achieved in sparsely populated networks, as the density and proximity of mobile transceivers increases, so does interference, and the systems fall back to the slower data rates (about 2 Mbits/sec). Thus, the higher speeds may be real, or just "virtual," depending on the specific applications and equipment densities. Medical applications often are characterized by high transceiver density and near-field interference problems.
The real answer to higher speed is the new 5 GHz band. A few suppliers already offer hardware to operate in these frequencies. However, the immunity to interaction with other medical devices in the inpatient setting at these frequencies will be a matter of some concern and ongoing investigation, particularly if power levels are also throttled up as well. 5 GHz is an unlicensed band, using a fundamentally different modulation technique, which achieves sustainable data rates of 50 to 55 Mbits/second, roughly equivalent to "fast" Ethernet in cabled LANs, and five to 25 times faster than conventional spread spectrum units operating today at 2.4 GHz.
The nice thing about these various technologies is that they are not mutually exclusive; rather, they can be used together to craft wireless network, cellular systems across entire healthcare campuses. They can also be mixed with cabled ethernet LAN solutions, to take advantage of the best characteristics of both, and to support the increasingly mobile healthcare provider, be they doctors, nurses, case managers, respiratory therapists, or whom ever.
It is interesting to consider the array of companies that have entered the medical vertical market, and who have avoided it or only dabbled in it. Some of these companies are shown in the accompanying table.
The application of wireless LAN technology has so far been applied in medical settings to the portable computer terminal (Jupiter-class Windows CE and above), and on a more limited basis to portable patient monitors themselves. These are two quite different applications, as the second requires real-time, non-interrupted transmission of patient vital signs data. This is not a capability that the spread spectrum devices can necessarily guarantee, particularly as the 2.4 GHz band becomes more crowded with commercial and other W-LAN products, and therefore the use for patient monitoring WLAN has been much more limited than for information systems applications. Interest ingly, Criticare Systems (Waukesha, WI) has used Xetron’s (Cincinnati, OH) 900 MHz. spread spectrum transceivers in its MPT patient-worn telemetry system, but it is one of the few companies to do so, and intentionally avoided the 2.4 GHz band. Portable telephone technology is the other major user of unlicensed, spread spectrum 900 MHz bands.
The WLAN technology is being pushed down to the least capable computing platforms in healthcare, appearing in hand-held personal information managers (PIMs), like the popular 3-Com Palm Pilot devices, as well as many others, and also in the new Jupiter-class devices, like CLIO from AVIO Corp. To each of these platforms, as well as to the traditional laptop portable computer, the new developments and increased speed of wireless means more robust performance, and faster response time in the user interface of these devices, as the user will not have to wait as long for the WLAN link to handle the data being exchanged. The speed gain alone will be enough to encourage continued growth in the utilization of this technology in a growing number of portable, CPR medical applications. It also will encourage more hospitals to implement WLAN technologies as part of their network infrastructures, and by doing so will become an enabling technology for the mobile healthcare worker, particularly doctors and nurses who are then free to "roam" the healthcare enterprise without losing the ability to interact with patients and other staff.
In the longer term, however, these most recent gains are only a step on a path of wireless communication infrastructure consolidation. As the patient-to-staff ratios in hospitals continue to be sacrificed on the altar of cost savings, efficient communications will become an increasingly important issue. Nurses already are being equipped with conventional and specialized (from Data Critical, Redmond, WA) pagers, cellular phones, or both. At this year’s HIMSS exhibition, we saw the integration of these devices into "patient call" systems. Within the next two years, we will see the merger of all of these wireless technologies, as well as linking with IR devices, already a part of the IEEE 802.11 specification. When this consolidation has occurred, it will change the healthcare equipment landscape in very fundamental ways, blurring the boundaries between traditional medical product segments. Companies that successfully foresee and are proactive to this technology shift will be in an excellent position to displace larger rivals whose product lines are conceived upon older communication concepts.
These consolidating communication technologies will change the very notion of ICU monitoring as early as the next generation of products, by providing the universal communication conduits upon which the emerging open-communication, industry standards like the revised MIB, HL7+XML, and others will communicate. In the wake of this technology shift, entire product segments, such as nurse call, paging, patient monitoring, will disappear into broader communication segments, and become products within much broader new market segments.
Thus, the improved speed of wireless showcased at HIMSS was but the early harbinger of a much more fundamental shift to come in medical, wireless communications.
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