January, 2007Doc: IEEE 802.15-06-0569-00-0ban Zhen, Li, Kohno (NICT) Slide1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

January, 2007 Doc: IEEE 802.15-06-0569-00-0ban

Zhen, Li, Kohno (NICT) Slide 1

Project: IEEE P802.15 Working Group for Wireless Personal Area Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)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 ZhenVoice:[+81 46 847 5445, E-Mail: [email protected]]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.



Consideration of implantable biomedical systems

B. Zhen, H.-B Li and R. Kohno

National Institute of Information and Communications Technology (NICT)



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



High rate implantable applications

Applications Requirements Detail

Wireless capsule endoscope (gastrointestinal …)

<2Mbps (uplink) 2.4GHz, ASK, compressed image (2.18 bit/pixel), sleep/active mode, remote control, <200kbps

Analog TV signal @ 315MHz,

External control @ 433MHz (Korea)

Cortical stimulator (auditory, visual, Parkinson’s, …)

<3Mbps (downlink), inductive energy couple

32 sites, FSK (0/5MHz, 1/10MHz), 2.5Mbps,

>1mW power, 250uA stimulation current (U. of Michigan)



Low rate implantable applicationsApplications Requirements Detail

Remote control (pacemaker, actuator …)

Inductive link (<1Mbps,

asymmetric uplink and downlink)

Infrared

Carrier frequency (2.5MHz, 4MHz, 10MHz, 13.56MHz …)

Modulation (ASK, OOK, FSK, burst sequence, BPSK, LSK)

Data rate (125Kbps, 200kbps, 250kbps, 1.12Mbps)

Vital signal (pH, pressure, glucose, cardiac arrhythmia …)

ISM, MICS and UWB link

15.4b

433MHz (40kbps, ASK, <5m)

403MHz (SubQore, 400kbps, <2m, 0.5% duty cycle)

UWB@3~5GHz (OOK, 1.2Mbps, 100uw, <0.5m, monopole antenna)

Power delivery Inductive coil 35Ω coil receiver, 4~13.2mW, 40kHz, 15kHz



Implantable device

Power supply

Processor

Transceiver Interface

Battery

Energy scavenging

External coupling

Inductive link

ISM, MICS

Sensors (image, pressure, glucose, …)

Actuators(stimulator, drug

pump…)

Peripherals (EEG, EMG…)

Analog

Infrared

Power management



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



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



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



Scenarios

Piconet A Piconet B

A1A2 B1 B2

A3

IEEE 802.15.4b network @ 2.4GHz ISM band, 1mW transmission power



Reception power analysisAssumption 20mm tissue media (-40dB tissue attenuation)

Maximal distance from implant to an external receiver is <2m

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-95

-90

-85

-80

-75

-70

-65

-60

free space distance (m)

rece

ptio

n po

wer

(dB

m)



Carrier sense analysis

Free space devices can sense activity of implant when distance is <2mImplant devices can sense activity of another implant when free space distance is <0.2m

Assumption 20mm tissue media (-40dB tissue attenuation)

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-130

-120

-110

-100

-90

-80

-70

-60

free space distance (m)

CC

A p

ower

(dB

m)

external CCA

implant CCA



0 1 2 3 4 5 610

-7

10-6

10-5

10-4

10-3

10-2

10-1

100

BE

R

piconet separation (m)

co-channel

adjacent channel

Coexistence among BAN piconets

Assumption two piconets -30dBm adjacent channel limit 1m from implant to external receiver

Minimal separation between two piconets in adjacent channelsshould be >3m

Interference from a free space device to implantable device



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

Documents

January, 2007Doc: IEEE 802.15-06-0569-00-0ban Zhen, Li, Kohno (NICT) Slide1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)