Page 44 - GlobalCE 1st Special Issue

Hoglund and Varga: Building a Reliable Wireless Medical Device Network

a well performing patient monitoring system. As WLAN designs must anticipate the potential number
mentioned above, predictive WLAN modeling tools of client devices such as patient monitors that will
ensure a design with over 98% accuracy before be used over the life of the WLAN. Today there are
implementation. For the few instances where the tools from such companies as Ixia (www.ixiacom.
WLAN design may incorrectly place Wireless Access com) that allow end users and WLAN device manu-
Points (WAPs), WAP location modifications can eas- facturers to assess the scalability of a WLAN. Given
ily be made in the field at the time of deployment. the new higher-speed WLAN standards, it is common
When installing a WLAN, all operational settings to build and scale networks to thousands of users
are configured in a central WLAN controller that to support data, voice, video, and WLAN-enabled
interfaces with the facility’s core network and allows medical devices.
for efficient network communication. In addition,
• Two-way communication: Previous generations of
depending on the size of the WLAN, a separate WLAN
proprietary wireless communication for telemetry
management system may also be implemented to
was unidirectional; WLANs offer two-way or bi-
provide a single “pane of glass” for the management,
directional communication. Two-way communica-
monitoring, alarming, troubleshooting, reporting,
tion supports the latest generation of patient-worn
and assurance of consistent configurations across
monitoring devices. These devices send patient vital
multiple WLAN controllers. All of these improve-
signs data to the central monitoring station for display
ments make the implementation of a reliable LAN
and alarming, as did yesterday’s telemetry transmit-
and WLAN scientific and predictable.
ters, but they also display and alarm locally. So, if
• interference: While RF interference is always a pos- the patient accidentally walks outside of the Wi-Fi
sibility, the modern WLAN generally has spectrum network coverage area, the patient will continued
analysis functions built into the network as a whole. to be monitored locally. The caregiver is therefore
This allows for constant monitoring of the network for able to monitor the patient without compromising
any interference and acts to either issue an alarm to the mobility of ambulatory patients.
the network administrator or automatically mitigate
• Cost issues: Healthcare systems are under tremen-
those specific interferers. As good design practice,
dous cost pressures, so the more value that they can
an onsite spectrum analysis should be performed to
realize from a technology investment, the better. In
determine any RF interferers present in the facility
the case of patient monitoring, this is yet another
in the 2.4GHz and 5GHz bands and their potential
application across which to allocate the fixed WLAN
impact.
cost. More than likely, the investment in the WLAN
• Reliability: Today’s WLAN is an intelligent network. was made for Bar Code Medication Administration
Although WAPs have a mean time between failure (BCMA), wireless voice-over-IP (VoIP), real-time
(MTBF) of over ten years, this network can auto- location services (RTLS), and/or “smart” infusion
matically sense and alarm if a WAP fails or is not pumps. Adding WLAN-based patient monitoring
performing as expected. Good WLAN design practices may add some small incremental costs, but this
dictate overlapping adjacent WAP cells to ensure application can be amortized over a number years
seamless client device roaming across the network. with the other applications to improve the return
Even if an individual WAP fails, radio output power in on investment (ROI).
adjacent WAPs can be set to automatically increase/
decrease to ensure adequate coverage. In addition, Wi-Fi vs. WMts cost comparison
High Availability (HA) designs feature redundant
The costs of implementing patient monitoring on
WLAN controllers that will failover in a seamless
Wi-Fi are significantly less than on a WMTS network.
fashion in the event of a network controller failure.
The following cost comparison tool provides a general
• Scalability: In the past, understanding how the indication of costs involved.
WLAN client density may increase was a challenge.

J Global Clinical Engineering Special Issue 1: 42-49; 2018 44