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Hoglund and Varga: Building a Reliable Wireless Medical Device Network

yourself from buying a device with a sub-par radio. More and driver firmware and, once that is completed, progress
on that in the next section. to assessing the real-world performance of the medical
Another costly misconception is that a radio obtain- device itself.
ing a stamp of approval from the Wi-Fi Alliance means Hospitals have the right to ask manufacturers if their
everything will work fine; but there’s more to it than that. devices have been tested or installed successfully in a
The Wi-Fi Alliance was founded in 1999, the same year similar configuration to what they are considering. The
that the IEEE approved the extended version of 802.11 proven methodologies should include:
(802.11b) standard for the specific purpose of ensuring 1. Base-lining network performance using “golden” clients
interoperability between client radios and wireless ac- to obtain a “best-case” use model
cess points.
2. Base-lining device performance under ideal network
The interoperability testing conducted does not include conditions where it’s the only client communicating
modeling the specific characteristics of a data, voice, video, with WAPs under optimal conditions
or medical device client or the simulation of different
3. Assessing range and roaming capabilities by varying
mixed client traffic load environments; nor does it measure
RF signal attenuation to prompt devices under test
application performance. Obtaining the Wi-Fi Alliance’s
(DUTs) to move away from and between specific WAPs.
stamp of approval is a great start, but it’s far from the end.
This includes:
The fact that a radio is Wi-Fi approved, or subscribes to • Determining device association to the WLAN at
802.11i and 802.11e, does not demonstrate how well the various ranges
roaming algorithms will work, or assess the passing of • Measuring the accuracy of device throughput,
security supplicants. Many healthcare institutions employ latency, and packet loss characteristics
WPA2 or other enterprise-level WLAN security methods • Assessing performance as devices travel across
but differ in how they implement security methodologies, multiple WAPs to emulate patient mobility. Test-
which in turn impacts device and application performance. ing should progress from simple setups using only
In selecting the optimal WLAN-embedded radio, two WAPs at a time to complex scenarios where
device manufacturers must assess the ability of the com- the device sees multiple available access points
ponents to meet their intended use for quality of service, broadcasting at different signal strengths.
roaming, and varying security implementations. As the 4. Assessing real-world performance and security by
mobile healthcare ecosystem grows ever more complex, simulating live network conditions. Generating high
embedded radio strategies must be able to accommodate traffic loads and interference allows the resilience,
all enterprise-grade security strategies and effectively coexistence, and security capabilities of devices to be
roam amidst a myriad of traffic types throughout a highly realistically and thoroughly assessed. User-configured
mobile environment. clients should be generated to populate a realistic
network ecosystem containing device traffic typically
It behooves the hospital to choose devices that contain
found in healthcare environments – voice over IP,
radios that meet their current requirements in order to
data from wireless infusion pumps, wireless laptop
provide a foundation for future requirements.
transactions, video, etc. – all generating simultaneous
Device testing: what it is and why it’s important network traffic.
5. Measuring interoperability with multiple WAPs and
The device manufacturer is responsible for testing
mobile clients and major customers’ preferred WLAN
medical client devices during validation and verification.
equipment vendors
A comprehensive methodology for testing the device
proceeds from highly controlled lab testing to assess- 6. Quantifying application performance and quality of
experience (QoE) from the user perspective
ing performance in the field via open air. Testing should
include validating components such as radios, chipsets,

J Global Clinical Engineering Special Issue 1: 42-49; 2018 46