Conference Presentation
Reference
Power-and Delay-Aware Mobile Application-Data Flow Adaptation:
the MobiHealth system case study
WAC, Katarzyna, et al.
Abstract
Emerging healthcare applications rely on personal mobile devices to monitor patient vital signs and to send it to the hospitals-backend servers for further analysis. However, these devices have limited resources that must be used optimally in order to meet the requirements of healthcare applications end-users: healthcare professionals and their patients. This paper reports on a case study of a cardiac telemonitoring application delivered by the so-called MobiHealth system. This system relies on a commercial device with multiple (wireless) network interfaces (NI). Our study focuses on how the choice of a NI affects the end-to-end applicationpsilas data delay (extremely important in case of patientpsilas emergency) and the energy consumption of the device (relating to the service sustainability while a patient is mobile). Our results show the trade-off between the delay and battery savings achieved by various NI activation strategies in combination with application-data flow adaptation. For a given mobile device, our study shows a gain of 40-90% in battery savings, traded against the higher delays (therefore applicable [...]
WAC, Katarzyna, et al. Power-and Delay-Aware Mobile Application-Data Flow Adaptation: the MobiHealth system case study. In: Proceedings of the 10th International Conference on e-health Networking, Applications and Services - HealthCom 2008, Singapore
(Singapore), 7-9 July 2008, 2008, p. 20
Available at:
http://archive-ouverte.unige.ch/unige:72670
Disclaimer: layout of this document may differ from the published version.
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Kate WAC, HealthCom’08
Power- and Delay-Aware Mobile Application-Data Flow Adaptation
the MobiHealth system case study
Katarzyna Wac (Kate), PhD student
Pravin Pawar, Bert-Jan van Beijnum, Richard Bults Mortaza Bargh, Arjan Peddemors
Kate WAC, HealthCom’08
Outline
• Introduction
m-health services: from MobiHealth project to MobiHealthTM system
• Problem Description
telemonitoring service: battery consumption, delays vs. NI choice
• Approach
measurements-based performance evaluation of service for different NIs
• Conclusions & Recommendations
which NI choice is best for which application flow?
Kate WAC, HealthCom’08
Introduction
m-health services
from MobiHealth project to MobiHealth
TMsystem
health tele-monitoring services
general practitioner Mobile Network
Operator
medical specialist
Internet
mobile patient (BAN-MBU)
healthcare centre
e.g. 2.5/3G, WLAN
MobiHealth project
MobiHealth™ System
Kate WAC, HealthCom’08
MobiHealth System History
2002-2004: MobiHealth – EU IST-2001-36006 (5 countries) m-health services: technically feasible? (emerging 2.5G/3G) 2005-2006: HealthService24 – EU eTEN-517352 (4 countries) m-health services: clinically/commercially feasible?
2004-2008: Freeband-Awareness – Dutch BSIK-5902390
m-health services: proactively context-aware? (security/privacy?) from 2007: MobiHealth BV – University of Twente (NL) spin-off commercial m-health services: platform for any sensor system?
2007-2009: Myotel – EU eTen-C046230 (4 countries)
telemonitoring/teletreatment services: chronic neck-shoulder pain?
Kate WAC, HealthCom’08
Problem Description
telemonitoring service:
battery consumption, delays vs. NIs status
Kate WAC, HealthCom’08
Problem description
Focus: explorative study
• mobile: limited processing, communication, storage, battery capacity
• mobile health services need to support emergency & non-emergency cases
• health telemonitoring service performance:
• data delay
• battery consumption
How to choose NI and parameterize application flow to
• match delay requirement to emergency/non-emergency case and
• minimize battery consumption
=f (NIs status)
Kate WAC, HealthCom’08
Approach
measurements-based performance evaluation
of telemonitoring service for different NIs
Kate WAC, HealthCom’08
Measurements Setup
MobiHealth™ system used
• cardiac patient case: 3 leads ECG, heart rate*, SpO2, pleth, alarm (128 Hz)
• MBU: Qtek 9090, Windows Mobile® 2003 (!battery drain!)
• main battery: Li-ion polymer 1490 mAh
• NI: Bluetooth (always ON gathering data from MOBI™)
• NI: WLAN (802.11b, OS ‘best-battery’ setting)
• NI: WWAN-GPRS (class 10: 4+1/3+2 slots)
• Application flow: 5-14 Bytes, 128Hz
• aggregation: 1 second of data
• compression (ZIP): 38-85 %
• TCP-IP end-to-end path
• continuous: ~1.2-1.5, 5.5 or 7.7 kbps
• bursts: 5.5 or 7.7 kbps, ~ Mbps
*heart rate is derived from 3 leads ECG
NI status: ON-IDLE-OFF
MOBI
MBU
Kate WAC, HealthCom’08
Approach: Measurements
Application-delay: App-RTT
• system response time for: telemonitoring/teletreatment
• does not require MBU & BEsys clocks synchronization
• MBU: measures it every 10 seconds
Kate WAC, HealthCom’08
Approach: Measurements
Remaining battery level (Windows Mobile
®)
• MBU: measures every 5 seconds
Measurements setup
focus
BAN BEsys
Kate WAC, HealthCom’08
Selected Findings
NI choice: consumed battery capacity
Min: GPRS ON-ACTIVE, WLAN OFF
Max: WLAN ON-ACTIVE, GPRS ON-IDLE
NI choice: App-RTT delay
Min: WLAN ON-ACTIVE, GPRS ON-IDLE Max: GPRS ON-ACTIVE, WLAN OFF
(inverted to the battery profile!)
emergency
emergency (if no WLAN)
?
NI activation strategies: power efficiency
S-EM emergency
continuous flow: WLAN ON-ACTIVE, GPRS ON-IDLE (S-EM) bursty flow: WLAN OFF/ON-ACTIVE, GPRS OFF
patient reachable?
Kate WAC, HealthCom’08
Conclusions & Recommendations
telemonitoring service:
which NI choice is best?
Kate WAC, HealthCom’08
Conclusions & Recommendations
• GPRS vs WLAN have complementary profiles
• GPRS: power consumption lower, App-RTT higher than WLAN
• App-RTT vs power consumption
• minimal App-RTT if continuous application flow
• minimal power consumption if application flow in bursts
• ? WLAN App-RTT lower when GPRS ON-IDLE than when GPRS-OFF
• Optimal choices:
• emergency: continuous flow (App-RTT efficient)
• WLAN ON-ACTIVE (GPRS ON-IDLE)
• GPRS ON-ACTIVE (WLAN-OFF)
• non-emergency: bursty flow (power efficient)
• WLAN ON-ACTIVE/-IDLE (GPRS ON-IDLE) Æ n=4 seconds of data
• GPRS ON-ACTIVE/-IDLE (WLAN-OFF) Æ n=6 seconds of data
• larger n are not power-efficient enough to be considered (+ patient unreachable)
Kate WAC, HealthCom’08
Future work
• More measurements
• NI activation-deactivation (ON-OFF) and NI-NI WLAN-GPRS handovers
• multiple MBU-devices, NIs, different locations (mobile!) and times
• detailed study on delay variation as f(NI)
• multiple application data flows with different App-RTT requirements
• NI activation strategy vs.
• monetary cost of networks usage
• security considerations
• Further QoS/QoE considerations for the Mobihealth system
• requirements & provisions
• towards dependable system Æ dynamic system adaptation e.g. self-healing
Kate WAC, HealthCom’08
www.healthservice24.com www.mobihealth.org
www.awareness.freeband.nl www.myotel.eu
www.mobihealth.com