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BEHIND THE TECHNOLOGY Wireless and Broadband Management for the Integrated Healthcare Network David H. Hoglund s the wireless mobility continuum continues Many forces are to unfold in healthcare, it is becoming critical “ converging in today’s A that disparate medical devices from all device wireless healthcare companies share the overarching wireless local area net- environment. How can work (WLAN) infrastructure. In addition, the voice and systems be deployed data requirements of new applications are demanding a consistently to ensure neutral host environment; since the healthcare environ- application integrity? ment cannot always control the end user, a multi-carrier —David Hoglund environment is needed. The radiofrequency (RF) environment is a dynamic this airspace to ensure consistency of signal strength and environment and spectral changes do occur due to elec- that the intended applications all work correctly. tromagnetic interference (EMI) and other factors. Years Cellular use within the healthcare environment is now ago, the main options were very high frequency (VHF) common, but concerns about electromagnetic interfer- and ultra high frequency (UHF) medical telemetry. ence remain. The standard ANSI/AAMI/ES60601-1-2, Now the wireless medical telemetry (WMTS) bands and Medical electrical equipment—Part 1-2: General require- 802.11a/b/g/n options are available. Other wireless fre- ments for basic safety and essential performance—Collateral quency options include Zigbee for building automation, standard: Electromagnetic compatibility—Requirements and Bluetooth headsets, RF identification (RFID) and RF tests specifically addresses radiofrequency (RF) suscepti- location systems (RFLS), and the proliferation of cellular/ bility. This standard offers a clear starting point to deter- personal communication service (PCS) and public safety mine medical equipment susceptibility to interference. devices all converging onto the healthcare scene today. Some recent studies have shown that the potential for This paper will explore two areas vital to healthcare EMI from cellular voice and data devices is low, but that facilities: 1) the correct test environment and design the value proposition of these devices for improvements models for a WLAN infrastructure to support the quality in productivity are high. In its proceedings published of service requirements needed for a life critical wireless in March 2007, the Mayo Clinic1 concluded “… EMI network; and 2) design considerations that will ensure is unlikely to occur in a hospital setting and … internal the broadband requirements are met for the in-building regulations in health care facilities should reflect that fact. wireless space. Recommendations should also reiterate that the risk is not zero and that medical personnel should remain vigi- Drivers of Change lant in order to detect and mitigate the uncommon oc- Many forces are converging in today’s wireless healthcare currence of clinically relevant EMI of medical devices.” environment. Medical device companies are increas- Quality of service expectations have been set by im- ingly embedding 802.11a/b/g client adapters in devices proving mobile communications experiences outside like infusion care systems and patient monitors, giving of buildings. Healthcare users are now demanding this them built-in wireless capabilities. A myriad of wireless same mobile experience whether in the operating room, medical devices like bar code medication administration hallways, or basement of the building. Options for ex- systems and workstations on wheels are being deployed. panding wireless cellular, PCS, and public safety coverage How can these systems be deployed consistently in the technologies into healthcare buildings must be carefully healthcare environment to ensure application integrity? explored for benefits and potential problems. There is an Healthcare network managers must accurately monitor expanding need to provide in-building distributed anten- 2008 IT Horizons 39 BEHIND THE TECHNOLOGY na system (DAS) coverage to enable mobility improve- will be able to establish and maintain the connection ments. However, combining 802.11a/b/g onto a DAS is under various circumstances to include perhaps poor not always straightforward, and there is often a case for coverage and different roaming situations? How can they multi-carrier coverage as well as public safety coverage in evaluate the impact of numerous application traffic pat- such an in-building system. Healthcare network manag- terns and loads expected to run on the hospital’s Wi-Fi ers must proactively manage the wireless environment network? Can they be confident that the medical device and all its different modalities—including 802.11a/b/g/n, application is reliable in a real-world deployment? WMTS, public safety coverage, cellular, and PCS—and Performance validation should include evaluation of be alert to any problems that are occurring in the net- the distance at which the medical device application will work or with new technology deployments. maintain a reliable connection. How will this applica- tion act in the presence of other traffic using the same Ensuring Quality of Service: access point? There should be a way to determine and The Test Environment analyze the application performance while roaming in a Meeting quality of service requirements for medical repeatable environment. Finally, there should be a way to devices on a wireless network is essential for success. To generate service level agreement (SLA) reports provid- ensure this quality of service, application testing must ing detailed client results. SLAs can contain numerous be conducted. Quality of service simply means the ex- service performance metrics with corresponding service pectation is that the communications link for a medical level objectives. device on a wireless network should take precedence over Traditionally, accomplishing these goals required a any other data and voice traffic. But how do you actu- lab environment. The traffic generating client devices ally ensure that the medical device within this network such as Voice over Internet Protocol (VoIP) phones, cli- has priority, and who is going to take responsibility for ent laptops, etc. had to be reproduced—no small task. ensuring the needed quality of service? In addition, scaling the number of devices to emulate a Network managers who want to use medical devices realistic hospital WLAN environment is challenging and with embedded 802.11a/b/g/n radios on an enterprise difficult. WLAN face several challenges. For instance, how can A potential solution that provides scaling and de- they demonstrate that the actual device and application vice emulation is now available from a company called VeriWave, based in Beaverton, OR (www.veriwave.com).2 Another so- lution from Ixia, based in Calabasa, CA (www.ixiacom.com) has been used by enterprise customers to test VoIP performance. These test tools allow a virtual test environ- ment to be developed and used in an isolated lab environment. They allow a consistent methodology and reproducible results that can ensure consistent deployments of medical device applications across the enter- prise healthcare environment. The testing systems may create inconsis- tent traffic patterns to test realistic conditions, like traffic spikes. But the methods used are controlled and the results are reproducible and Figure 1. This image from VeriWave describes a device under testing (DUT), in this case a patient monitor set up in a virtual test environment to test roaming between wireless access points and performance and/or band- reflective of future performance in width loading scenarios. a live environment. 40 IT Horizons 2008 BEHIND THE TECHNOLOGY At a minimum, testing criteria as per VeriWave guide- use models. The ability to spectrally monitor the WMTS lines should include the ability to provide up to 500 fully bands is not provided today in off-the-shelf tools. The independent 802.11 client state machines per port to healthcare environment is probably the most RF chal- enable precise measurement of critical performance met- lenged environment today, partly due to the structural rics. Complete client control should be provided over characteristics, such as lead lined walls, old construction, median access times to identify aggressive non-compliant fluids, a myriad of movable metal equipment, and just the clients and study the effects on the wireless access point mobility requirements to take care of patients. All of this and centralized wireless LAN controller for the manage- significantly increases the propensity of “multipath” or ment of the wireless access points (APs) as well as medi- drop out of the RF signal. Multipath is the propagation cal devices. Built-in transmit power attenuation and per phenomenon that results in radio signals’ reaching the packet frame error should be allowed that will emulate receiving antenna by two or more paths. Having “real real-world distance between the AP and the client. time” spectrum analysis would be a huge benefit for the Test environments should allow the introduction of wireless healthcare environment of today. real-world effects such as hidden node issues that cause Electromagnetic interference is an undesirable dis- client collisions resulting in malformed packets to the turbance that affects an electrical circuit due to electro- AP. Finally, user customizable client behavior and traffic magnetic radiation emitted from an external source. EMI types ranging from raw

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