Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Consideration of implantable biomedical systems] Date Submitted: [January, 2007] Source: [Bin Zhen, Huan-Bang Li and Ryuji Kohno] Company [National Institute of Information and Communications Technology (NICT)] Contact: Bin Zhen Voice:[+81 46 847 5445, E-Mail: zhen.bin@nict.go.jp] Abstract: [This document analyze the performance of IEEE 802.15.4b for implantable systems.] Purpose: [potential technologies for BAN healthcare application.] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15.

2. Consideration of implantable biomedical systems B. Zhen, H.-B Li and R. Kohno National Institute of Information and Communications Technology (NICT)

3. Motivations • Where to start BAN standardization? • from implantable application point of view • Review of implanted device research • Performance analysis of IEEE 802.15.4b for implantable communication

4. High rate implantable applications

5. Low rate implantable applications

6. Energy scavenging Battery External coupling Actuators (stimulator, drug pump…) Inductive link Sensors (image, pressure, glucose, …) Peripherals (EEG, EMG…) ISM, MICS Analog Infrared Implantable device Power supply Processor Power management Transceiver Interface

7. Review summaries • Review of >40 published papers • Most of efforts are on implementation • Communication is not optimized • Suitable frequency band • Inductive link: <20MHz • MICS, ISM and UWB link: < 5GHz • IEEE standards15.4b @ 2.4GHz and UWB @ 3~5GHz are OK for low data rate application • The data rate and receiver sensitivity can support through body propagation

8. Characteristic of implantable BAN • Through body attenuation • Compared with free space pathloss (n=2,3,4), there is an additional 30-35dB attenuation at small distance in the far field • “Towards a propagation model for wireless biomedical applications,” ICC 2003 • Energy couple

9. New issues of BAN • Power issue • Cortical stimulation • Data rate issue • 250kbps is not high enough • Coexistence issue • among wearable device and implanted device • Capture effect prefers wearable device to implanted device • among BAN piconets • Carrier sense issue • among implanted devices

10. Scenarios IEEE 802.15.4b network @ 2.4GHz ISM band, 1mW transmission power B1 B2 A2 A1 A3 Piconet A Piconet B

11. Reception power analysis Assumption 20mm tissue media (-40dB tissue attenuation) Maximal distance from implant to an external receiver is <2m

12. Carrier sense analysis Assumption 20mm tissue media (-40dB tissue attenuation) Free space devices can sense activity of implant when distance is <2m Implant devices can sense activity of another implant when free space distance is <0.2m

13. Coexistence among BAN piconets Assumption two piconets -30dBm adjacent channel limit 1m from implant to external receiver Minimal separation between two piconets in adjacent channels should be >3m Interference from a free space device to implantable device

14. Conclusions • Summaries of implant device research • New issues to consider implantable devices in BAN • Power issue • Cortical stimulation • Data rate issue • Up to 2Mbps • CCA issue • Carrier sense among implants • Coexistence of BAN piconet • Interference from free space signal to implantable signal