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Hoglund and Varga: Building a Reliable Wireless Medical Device Network

design tasks may include creating a completely new design radio is really dictated by chipset availability (for example,
or modifying the existing WLAN. This design can be then one would be hard pressed to find an 802.11b radio in
handed off to the hospital’s integrator for any potential 2014), power consumption, and feature set required by
remediation and/or additional infrastructure. the patient monitor. Wi-Fi clients built on earlier 802.11
standards will communicate with the same QoS (Quality
fRequeNTLy ASkeD queSTIoNS of Service) and security but simply may not be able to take
advantage of capabilities inherent in 802.11n and 802.11ac.
Why is it common for hospitals to use Wi-fi for bedside These include but are not limited to Channel Binding at
and transport monitoring, but not for telemetry? 40/80MHz, MIMO Spatial Streams and Multi-Use MIMO,
High Modulation 64 QAM and 256 QAM, beam-forming
It has been easier for medical equipment manufacturers
and co-existence mechanisms for 20/40/80/160MHz.
to design Wi-Fi into a bedside and transport monitor due
When the healthcare enterprise desires to move forward
to the looser constraints around Wi-Fi power consump-
with 802.11n and then 802.11c, adding the low bandwidth
tion and associated battery life. Portable monitors tend
requirements of patient monitoring will have little to no
to be powered by battery and AC line power and tend to
impact on the overall wireless infrastructure.
be used for shorter periods of time. Until most recently,
Wi-Fi radios tended to be relatively power hungry. Telem-
How do I know that Wi-fi will be reliable for a life-
etry monitoring is wearable, requiring smaller batteries critical medical application when the spectrum is already
to conserve weight and space, and has a requirement for crowded with data, voice, etc.?
the devices to be worn for days.
The evolution of Wi-Fi has been to primarily increase
When I look for Wi-fi based patient monitoring, is networking speed, quality of service, and security. Wi-Fi
the particular WLAN technology important – such as has evolved to a level of performance capability whereby it
802.11a, b, g, n, or ac? is now displacing the wired Ethernet network at the access

layer. Those applications with low bandwidth require-
ments, such as infusion pumps and patient monitoring, will
reliably function in the 802.11g (2.4GHz) and/or 802.11a
(5GHz) spectrums. Since 802.11n is backward-compatible
with both ‘g’ and ‘a’, those same monitors will work well
in a 802.11n WLAN infrastructure. Applications such as
high-end video will tend to migrate to 802.11ac operating
in the 5GHz band. Therefore, all applications can co-exist
successfully on a modern WLAN network.
Modern WLAN systems increase overall system reli-
ability using:
TAbLE 2. History of IEEE 802.11
• Persistent spectrum analysis to identify RF interfer-
The evolution of Wi-Fi has been driven by the radio ers and proactively reconfigure RF channelization to
manufacturers and IEEE standards seeking increasingly work around the interference
higher performance networks with increased radio spec- • Applying best practices for networking design and
trum efficiency. Here is the history of IEEE 802.11. deployment for Quality of Service (QoS) to prioritize
What is important is to focus on the application and use patient monitor system traffic over other traffic types
model. Patient monitoring data throughput requirements • Applying best practices for networking design and
are extremely low and do not need the high speed capa- deployment for network segmentation via VLANs that
bilities of 802.11n and 802.11ac chipsets. The choice of address scalability, security, and network management

J Global Clinical Engineering Special Issue 1: 42-49; 2018 48