IEEE Solid-State Circuits Magazine - Fall 2017 - 40

two frames until the next data set is
ready. However if the sensor fails to
transmit its data, there are two fur-
ther attempts to transmit before the
packet needs to be dropped since new
data is available.
The data payload was divided
into 15 packets; with three times
the redundancy, we have the oppor-
tunity to transmit 45 packets, of
which only 15 need to be received
successfully. Running a simulation
of link reliability using a model of
the 802.15.6 protocol and assum-
ing a bit error rate of 1E-3 gives the
results shown in Figure 5. The total
probability of dropping more than
30 packets is lower than 2E-6, and
this is well within our reliability tar-
get of 50 E-6.
To validate this application in sili-
con, we implemented a custom SoC
in 65-nm CMOS with a peak power
consumption of <15 mW in transmit
mode and <10 mW in receive mode;
for further details, see [21]. Although
this work currently remains a re -
search project, it illustrates the pos-
sibility of deploying low-power and
high-reliability links in demanding
wireless medical monitoring appli-
cations through the close coupling
of protocol design and low-power
hardware implementation.

Conclusions
Although the medical device industry
is slow to replace wired by wireless
connectivity, the convenience and
other benefits that wireless can bring
means that new applications for wire-
less patient monitoring are starting
to emerge. Since the development of
low-power standards is mainly driven
by consumer and other large markets,
it is inevitable that such standards
do not currently prioritize the high
reliability and security requirements
needed by medical devices. However,
as the market keeps developing, we
anticipate that the needs currently
addressed by custom or niche wire-
less protocols and SoCs may begin
to be met by widely available off-the-
shelf devices.

40

FA L L 2 0 17

Acknowledgments
The author acknowledges the input
of all colleagues at Toumaz and
Sensium Healthcare, in particular
Okundu Omeni for work on system
simulations.

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About the Author
Alison Burdett (alison.burdett@
sensium-healthcare.com) has more
than 30 years of experience in elec-
tronic engineering and semiconduc-
tor design, particularly in the field of
ultra-low power wireless communi-
cation for medical applications. She
joined Toumaz in 2001 as technical
director and became chief technical
officer in 2006. In 2016, the health-
care business unit of Toumaz, Sen-
sium Healthcare, became part of
The Surgical Group, and she joined
Sensium, where she serves as chief
scientific officer. Prior to joining Tou-
maz, she spent time in industry as
an IC designer and in academia as a
senior lecturer in analog IC design
at Imperial College London. She is a
chartered engineer, a fellow of the
Institute of Engineering and Tech-
nology, and a Senior Member of the
IEEE. She is chair of the Technical
Program Committee for the Interna-
tional Solid-State Circuits Confer-
ence. She is a member of the U.K.
Engineering and Physical Sciences
Research Council Strategic Advisory
Network, and a visiting researcher
at the Institute of Biomedical Engi-
neering, Imperial College.
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