1.
Scalable Wireless ECG Streaming
Mo Alloulah, Mark Dawkins, and Alison Burdett
Toumaz
MobiCASE ’16 - 30 Nov 2016

2.
Outline
• Context
• Problem (formulation + approach)
• Results

3.
Digital healthcare
• wireless vital sign monitoring
• patients, elderlies, wellness
• @ forefront of 1st IoT wave
• ultra low-power + small form factor
• challenging system-level design
• integration (analogue + digital)
• medical-grade algorithms
• cross-layer in DSP
• machine learning for diagnosis

4.
The Patch
• designed to record and wirelessly relay
• medical-grade vital signs
• temperature
• blood pressure
• respiration
• heart rate
• electrocardiogram (ECG)
• example use case
• surgical ward monitoring of patients at risk of
deterioration following serious procedures
• e.g. organ transplant
• early detection
* Toumaz Healthcare. 2nd generation SoC Functional Specifications.
Technical report, July 2016.

5.
Current Medical Practice
• Nurses rota e.g. every 6 hours
• archaic!
• Ageing population*
• unsustainable demand
• Healthcare automation
• imperative!
* United Nations (2015). World Population
Prospects: The 2015 Revision.

6.
Business Case
• Scaling per-night & per-bed cost
• intensive care unit (ICU)
• heavy instrumentation e.g. bedside monitor
• $$$
• general ward
• order of magnitude cost reduction
ICU
general ward
i.e. cache patients

7.
Problem:
ECG Streaming
• Hospital requires continuous ECG streaming
• wirelessly
• reliably (medical-grade QoS)
• up to 32 co-located users
• for 48 hours
• on a single charge
• i.e. approximate performance of expensive bedside
monitor using low-cost disposable patches and scale
vs.

8.
Electrocardiogram*
The Heart*
* Navas, S., Atrial Fibrillation: part 1. Nursing standard, 2003.
17(37): p. 45-54.

9.
BAN channel
• Pathloss stats
• Walking
• red 900M
• blue 2.4G
• distribution
• function of
• distance
• angle
• frequency band
• Non-wide-sense-stationary
body area network channel
• variable pathloss

10.
Pathloss variabilities – two examples
2.4G, 4m, 90o 900M, 2m, 180o

11.
Approach: joint source-channel coding
• Borrowed concepts from mobile wireless video
• Szymon Jakubczak and Dina Katabi. 2011. A cross-layer design for scalable mobile video.
MobiCom '11. ACM, New York, NY, USA, 289-300.
• Siripuram Aditya and Sachin Katti. 2011. FlexCast: graceful wireless video streaming.
MobiCom '11. ACM, New York, NY, USA, 277-288.
• Degradable ECG Streaming
• burn minimal current in transmission
• instantaneous channel determines signal quality

12.
Proposition
• Transform separate source coding (i.e. compression) and channel
coding (i.e. error protection) into one linear operator
èwaveform degradation proportional to channel errors
èrelax link budget
èconserve current at patches
Channel
error protection
source
compression
compression + error protection
waveform bits
waveform

13.
How
• Block operator
• extract ECG similarities in a block
• within a cycle
• across cycles

14.
But
• ECG can be all sorts
• e.g. rate, morphologies

15.
Putting it together:
System Architecture

16.
Evaluation
• Performance
• very good compression & distortion
• across ECG morphologies
• scalability
• relax link budget
• increase network capacity
• robustness
• combat channel variations, contention, and interference
• low power
• save current in RF circuitry
• Linear coding
• gracefully degradable ECG

17.
Thank you

18.
Vital Signs Monitoring – at a glance
* Miguel Silveira. Introduction to biomedical algorithms, Sensium Healthcare, 2016.