Jamil Khan, Ph.D.

Head Electrical Engineering Discipline University of Newcastle-Callaghan

1

Wireless Technologies for Wearable and Implantable Wireless Body Area Networks

Jamil Y. Khan and Mehmet R. Yuce SCHOOL OF ELECTRICAL ENGINEERING & COMPUTER SCIENCE

THE UNIVERSITY OF NEWCASTLE Australia

Date: 26 February, 2009

2

OUTLINE

    

Introduction Frequency Bands

- ISM, MICS, WMTS, UWB

Multi-Patient Monitoring via Body Area Network

- Sensor nodes, CCU, Hardware.

Some Measurement Results Conclusion

3

Wireless Body Area Networks

Visual C++ 2005 Express Edition is used • Vital Signs Monitoring • Medical close loop control • Healthcare • Fitness network, consists of a set of intercommunicating sensor nodes operating around human body, Wearable Implantable either wearable or 2m implantable for both Non - Medical medical and non-medical applications.

• Wireless Audio • Wireless Video • Wireless data control • User interface 4

Wireless Body Area Networks

• IEEE802.15 Task Group 6 was formed in November 2007, to develop a Visual C++ 2005 Express Edition is used • Requirement of Wireless Body Sensor Network (WBAN) – Limited range (<0.01 to 2 meter) – extremely low consumption power (0.1 to 1mW) for each device – support scalable data rate: 0.01 to 1000 kbps (option: 10Mbps) – Needs optimized, low complexity MAC and Networking layer – Application specific, security/privacy required.

– Small form factor for the whole radio, antenna, power supply system.

5

Current Status & Future

Wireless Body Area Network (WBAN): Sensors/ Electrodes Wires

Control box (Central Control Unit)

Receiving device

CCU

Wireless distance Wireless Chip:

Bluetooth 802.15.4 (Zigbee) WLAN

Local PC for monitoring EEG Sensor node electronics with wireless capability Tempr.

ECG PH Monitoring

CCU acts as an intermediate wireless node to connect other wireless technologies at remote monitoring locations

Stations Receiving devices 1 st Wireless distance

CCU

WiFi and Bluetooth dis 2 ta nd W nc e WiFi an M (G SM d Blueto e n , C etw DM ork A, e oth tc) ire les s

Person

Current application of WBAN

Person

Future application of WBAN

  Body area network targets both implanted and external nodes.

6 A wireless standard dedicated to WBAN is needed.

Wireless Technologies in Medical Monitoring

MICS WMTS UWB IEEE (802.15.6) Freq. Band 402-405 MHz 3 MHz 608-614, 1395-1400, 1429-1432 MHz 6 MHz Available Bandwidth Data rate Multiple Access Transmit Power Range >150 kbps Not specified - 16 dBm (25



W) 0-10 m -- Not specified ≥10 dBm and < 1.8dB (1.5 watt) >100 m 3-10 GHz >500MHz 850 kbps ALOHA -41dBm 2 m IEEE 802.15.4 (Zigbee) 2.4 GHz (868/915MHz Eur./US) IEEE 802. 15.1

(Bluetooth) 2.4 GHz 5 MHz 250 kbps (at 2.4 GHz) CSMA/CA 1 Mbps FHSS/ GFSK 0 dBm 0-10m 1 MHz 4 dBm , 20 dBm 10, 100m WLANs (or WiFi) (802.11b/g) 2.4GHz

20 MHz >11 Mbps OFDMA, CSMA/CA 250 mW 0-100 m



in addition to the ISM band at 2.4 GHz, there have been other bands that are considered for medical monitoring

7

Heterogeneous Networking in WBAN

•An interference free wireless medical network for monitoring physiological parameters in a hospital environment may be quite challenging since there are a number of other wireless systems (e.g. Wi-Fi, Bluetooth, ZigBee, Microwave oven) operating already for different purposes.

8

Application of WBAN in Hospital Environment Wireless RS232 Local PC Ethernet Remote PC a-) MICS wireless link d, wireless distance Scenario-1 Gateway BSN Ethernet

Hospital Ward

Centre Database room Local PC MICS BEDS Remote PC Data here can be accessed locally or through any other doctor’s cubicle on the network Scenario -2 b-)

 

a-) single patient user b-) multi-patient scenario

Two pieces of software were created in this project. - The job of GATEWAY at local PC is to gather data from the CCU through RS232 cable and forwards it to the remote PC through Ethernet Sockets -The BSN App will collate data from the local PC, interpret them and store them onto the remote PC to be analyzed later by health professionals 9

Application of WBAN in Hospital Environment



More than one room scenario

10

A Multi-hoping Prototype for WBAN

MICS CCU WMTS Control (base) station CCU Patients/Sensors 4-Channel sensor board Intermediate CCU board (It handles both MICS&WMTS Wirless links)



In our designs we implement MICS, WMTS,UWB, 433 MH ISM, and Zigbee prototypes to cover different environment in our WBAN.



MICS and UWB are also used for implanted nodes.

11

Wireless MAC Protocol Design

• Medium Access Control (MAC) protocol is one of the vital component of a WBAN • A MAC protocol determines the reliability and delay profile of a WBAN • Typically following MAC protocols are suitable for WBAN applications: – TDMA: deterministic QoS but not easily scalable – CSMA/CA : Good QoS at low load, QoS degrades at high load, scalable – Polling protocol: QoS can be maintained, scalable • MAC protocols along with routing protocols controls the energy use of a node • Zigbee based standard use the CSMA/CA protocol 12

Wireless Network Protocol Design

- A communication mechanism required to control data transmission from sensor nodes to a control box . Polling and CSMA/CA are used.

PC

Send a c haracte r Send data

CCU

Send add ress Send data Temperature Sensor Node Send add ress Send data Pulse Rate Sensor Node Sensor-n -low-power Sensor-2 Send add ress Send data Send add ress Send data Sensor-1 Send data T on T off Operation time

(a)

To GATEWAY (Local PC) -Complex -lower delay -reliable

13 (b)

Sensor Nodes

Block diagram/hardware implementation of sensor nodes

ECG/EEG Temp.

Pulse rate Amplifiers/ Filter/ Multiplexer 10-bit ADC Micro controller PIC16F785 3 V battery Antenna Radio Transceiver

A 4-channel sensor node hardware. 14

Development of Central Control Unit (CCU)

1 st Wireless

CC1000 PIC16F877

2 nd Wireless WMTS/ISM CCU-2 CCU-1 • • The primary function of the CCU is to collect all data from sensor nodes via the wireless MICS link and then transmit to the Data Collection Center via the internet.

CCU-2 includes a second wireless system : -to increase range -portable - to extend the applications in different environments.

15

CCU Node Design

CCU-1: a central control unit (CCU) used individually.

Spectrum for WMTS link CCU-2: Intermediate Central Control Unit (CCU). This device is shared by more than one patient and portable.

It receives signals from patients via the MICS wireless link and transmits to a base station (i.e. receiving device) via the WTMS wireless link. It uses two transceiver chips (AMIS and CC1010) to provide both wireless links.

16

Prototype Used in Implementation

• A prototyping system for a multi-hoping patient monitoring 17

Software Design Implementation

Visual C++ 2005 Express Edition is used • Data transfer through Ethernet connection 18

Software Design Implementation

19

Live Monitoring from Two-Patients

20

Monitoring ECG from Database

-

A data base server has been developed to maintain data integrity which is necessary for big medical centers.

21

Monitoring & Processing ECG

-Physiological signal can be exported tools like MATLAB for further analyzing and processing 22

Simulation of a Zigbee Based Multipatient Monitoring System

23

Performance Analysis of a Zigbee Based Multipatient Monitoring System

24

Interference Profile: WLAN and Zigbee Coexistence

25

A System Overview Using Wideband Communications

26

Electrode

Amp UWB Transmitter ADC Pulse Generator Bandpass Filter (4GHz)

Electrode

ADC + Demodulation UWB Receiver Diode Detector + Low Pass Filter LNA Bandpass Filter (4GHz)

26

What is UWB?

UWB is a narrow pulse baseband system, whose spectrum is spread across a wide range of frequencies. It is defined as a signal with fractional bandwidth (based on -10dB ) larger than 0.2 or at least 500 MHz.

IEEE802.15 Task Group 6 was formed in November 2007, to develop a standard for WBAN, low data rate UWB is one of the potential candidates under considerations.

Narrowband

27

-41.3

-75.3

UWB Spectrum mask Ultra Wideband (UWB) 0.96

1.61

2.4

3.1

5 Frequency (GHz) 10.6

27

Wireless UWB Prototype for Body Area Networks •A multiple channel EEG/ECG monitoring system using low data rate UWB technology has been developed •The system operates at 4 GHz central frequency and 1 GHz bandwidth

Continuous Vital Sign Monitoring Using UWB Band

a) ECG Signal from Oscilloscope 3 b) ECG Signal Corrupted with 50Hz Noise 2 1 0 0.5

1 1.5

2 Time (seconds) 50 c) FFT of corrupted ECG signal 0 -50 0 20 40 60 80 Frequency (Hz) 100 120 3 2.5

2 2 1.5

1 1 0.5

0 1 1 Time (seconds) 2.5

29

29

Monitoring Window

30

Summary



We presented some wireless body area network prototypes being developed by university of Newcastle for monitoring medical signals.



Implementing a wireless body area network will require integration of external and implanted nodes.



There are some challenges associated with design of microelectronics for sensor node electronics:

- Miniaturization - Antenna design (for implanted nodes) - Battery (power source management) 

A WBAN will most likely incorporate a narrow band together with UWB technology to cover different environments.

31