Feasibility of Gateway-less IoT e-health Applications C. PEREIRA, D. GUIMARÃES, J. MESQUITA, F. SANTOS, L. ALMEIDA, A. AGUIAR W O R K I N T H E S C O P E O F T H E N A N O S T I M A P R O J E C T ( N O R T E - 01-0145- F E D E R - 000016) M A C R O - TO- N A N O H U M A N S E N S I N G : T O WA R D S I N T E G R AT E D M U LT I M O D A L H E A LT H M O N I T O R I N G A N D A N A LY T I C S 18-21-jun-2018 EUCNC 2018, LJUBLJANA, SLOVENIA 1
e-health applications Becoming pervasive From tracking physiological parameters Heart rate frequency and variability, blood pressure, body temperature To monitoring populations Electronic Health Record (EHR) systems Powered by the Internet of Things Health personnel Hospital Medical database Paramedics 18-21-jun-2018 EUCNC 2018, LJUBLJANA, SLOVENIA 2
Wearable health sensors Myriad available! Embedded in bands (arms, wrists, legs, chest) clothes (shirts, socks, gloves) Typically wireless (short-range) Bluetooth technology dominates (BT / BLE) Connection to Internet requires a Gateway (e.g. smartphone) Protocol conversion (from BT / BLE to Internet, e.g. over WiFi) Processing to support appropriate middleware (e.g., M2M) Gateway Internet 18-21-jun-2018 EUCNC 2018, LJUBLJANA, SLOVENIA 3
Our use case an emergency ward Wristbands given to patients at check-in Continuous ambulatory monitoring (e.g., heart rate) Connect through Internet to an interoperable EHR But use of a Gateway is rather inconvenient Increases cost (infrastructure or smartphones) Not all patients have a smartphone Depletes smartphone battery Patients Can we use an IoT / M2M approach With wristbands connecting directly to the Internet And talking directly to an EHR? EHR Health personnel 18-21-jun-2018 EUCNC 2018, LJUBLJANA, SLOVENIA 4
Gateway-less Internet connection Ultra-Low-Power Low-Cost WiFi nodes Recent appearance in the market ESP8266, ESP32, Very small physical footprint 32-bit processor with WiFi Embedded antenna TCP/IP stack Several low power sleep states Direct connection to the Internet! Running open (M2M and EHR) protocols Internet Open questions? Is it really low cost? Can it run common M2M middleware? Which latencies are involved? How long can it operate from a battery? What is the operable range? 18-21-jun-2018 EUCNC 2018, LJUBLJANA, SLOVENIA 5
The ESP8266 nodes Main features 32-bit Tensilica processor @ 80 (160) MHz 36 kb on-chip SRAM + up 16 MB external SPI Flash IEEE 802.11 b/g/n/e/i compatibility (WiFi) TCP/IP stack with WPA / WPA2 Ultra-low-power Several sleep modes Allow switching off WiFi / CPU / Crystal clock Maintains real-time clock for wake-up control Low-Cost Under 2 Eur a piece 18-21-jun-2018 EUCNC 2018, LJUBLJANA, SLOVENIA 6
Interoperable EHR architecture Open protocols OneM2M + OpenEHR Field domain Infrastructure domain Low power application nodes ESP8266-based wristbands WiFi / Internet OneM2M (OneM2M broker) Wristband (publisher) Application Dedicated Nodes OpenEHR (subscriber) (ADN) - Application Entities (AND-AE) Infrastructure Nodes (IN) - Common Service Entity (IN- CSE) - Application Entities (IN-AE) 18-21-jun-2018 EUCNC 2018, LJUBLJANA, SLOVENIA 7
End-to-end latencies Communication requirements 1 HR sample/s 85 B/1s 10 HR samples accumulated 850 B/10s (OneM2M broker) Clock synchronization Same NTP server every 20s Access Point Beacon Interval 100ms DTIM 3 beacons Residual network traffic Wristband (publisher) t 1 (publication) OpenEHR (subscriber) time t 2 (subscriber notified) 18-21-jun-2018 EUCNC 2018, LJUBLJANA, SLOVENIA 8
End-to-end latencies M2M middleware timing overhead 20-40ms 18-21-jun-2018 EUCNC 2018, LJUBLJANA, SLOVENIA 9
Energy consumption and autonomy Measured current @ 5kHz Using a Monsoon Power Monitor Same scenarios 1 HR sample/s 85 B/s 10 HR samples accumulated 850 B/10s 1000 mah battery Linear depletion Lifetime estimated as time to reach 10% of the capacity 18-21-jun-2018 EUCNC 2018, LJUBLJANA, SLOVENIA 10
Energy consumption and autonomy Tolerates recharge cycles of >1.5 days in Modem Sleep >2 days in Light Sleep Compensates aggregating samples Specially in Light Sleep Still misses sensor consumption 18-21-jun-2018 EUCNC 2018, LJUBLJANA, SLOVENIA 11
Conclusion M2M communications are leveraging IoT e-health applications Smartphones have been used as M2M gateways Issues with cost, complexity and short autonomy Here we addressed the direct integration of wearable sensors in the Internet Bypassing gateways Using small, low power sensor nodes with WiFi interface Namely we tested the ESP8266 module We showed the ESP8266 is capable of Directly handling an M2M protocol (OneM2M) Exhibiting low end-to-end delay (20-40ms) Working continuously for 1-2 days from a miniature 1000mAh battery 18-21-jun-2018 EUCNC 2018, LJUBLJANA, SLOVENIA 12
Conclusion On-going work Characterizing range Modeling impact of AP support to low power devices (beacon interval and DTIM period) Using different M2M protocols A small step in the convergence to WiFi 18-21-jun-2018 EUCNC 2018, LJUBLJANA, SLOVENIA 13