Archana SapkotaDeepti ReddyPalden Lama

Project GoalDevelop a remote heart beat monitoring

system using wireless technology for new-born premature babies kept in hospital incubators.

The main goal is to alert hospital staff in case a babies’ heart rate is detected as abnormal.

Currently most hospitals use ECG (Electrocardiography ) for monitoring a baby’s heart rate but do not have remote monitoring system. Our project proposes a solution to upgrade existing health monitoring systems in hospitals by providing remote monitoring capability.

Comparison of Wireless TechnologiesZigBee 802.11

(Wi-Fi)Bluetooth

UWB (Ultra Wide Band)

Wireless USB

IR Wireles

Data Rate 20, 40, and 250 Kbits/s

11 & 54 Mbits/sec

1 Mbits/s

100-500 Mbits/s

62.5 Kbits/s 20-40 Kbits/s

115 Kbits/s4 & 16 Mbits/s

 

Range 10-100 meters

50-100 meters

10 meters

<10 meters 10 meters <10 meters (line of sight

Networking Topology

Ad-hoc, peer to

peer, star, or mesh

 

Point to hub

Ad-hoc, very small

networks

Point to point Point to point

Point to point

Operating Frequency

868 MHz (Europe)900-928

MHz (NA), 2.4 GHz

(worldwide) 

2.4 and 5 GHz

2.4 GHz 3.1-10.6 GHz 2.4 GHz 800-900 nm

Complexity (Device and application impact)

Low High High Medium Low Low

ZigBee 802.11 (Wi-Fi)

Bluetooth

UWB (Ultra Wide Band)

Wireless USB

IR Wireless

Power Consumpt

ion (Battery option

and life)

Very low (low power is a design

goal)

High Medium Low Low Low

Security 128 AES plus

application layer

security 

  64 and 128 bit encyption

     

Other Information

Devices can join an

existing network in

under 30ms

 

Device connection requires 3-5 seconds

Device connection requires up

to 10 seconds

     

Typical Applications

Industrial control and monitoring,

sensor networks, building

automation, home

control and automation

, toys, games

Wireless LAN

connectivity,

broadband Internet access

Wireless connectivity

between devices such as phones,

PDA, laptops, headsets

Streaming video, home

entertainment

applications

PC peripheral

connections

Remote controls, PC, PDA, phone, laptop links

Heart Rate monitors in marketProducts Feature Pric

e

Polar FS1 displays heart rate and exercise time, has visual & audible target zone alarms. Shows average heart rate of the total exercise.

$69

Alive Heart Monitor

uses wireless Bluetooth and mobile phone networks to immediately transmit ECG and accelerometer data to a computer, PDA, or central monitoring centre.

$100

BioHarness-Zephyr Technology

allows a user (or remote person) to view vital signs and status. Uses Bluetooth.

$120

Why ZigBee?Long range (10-100 meters)Long Battery Life (low power consumption)Secure communication (128 AES plus

application layer security)Low complexity at application layer (lot of

features available in the ZigBee stack)Quick network formation (Devices can join an

existing network in under 30ms)

ZigBee Protocol Stack

Application Layer

Z-Stack

The ZigBee monitoring system

An Incubator room with ZigBee network.

Remote Monitoring Architecture

Incubator

Room

Incubator

Room

Incubator

Room

Incubator

Room

Incubator

Room

Incubator

Room

Central Monito

ring Room

Experiments: Implementing a remote ZigBee monitoring systemWe implemented a ZigBee wireless network using

1 ZigBee Co-ordinator and 3 end-devices. A ZigBee Coordinator establishes the ZigBee

network, and collects heart rate information from various end-devices within the network.

A ZigBee end-device transmits the heart rate information to the Coordinator periodically. On detecting, an abnormal heart rate (above 160 beats/min and below 120 beats/min) for new-born babies, it sends the information immediately.

ZigBee Coordinator transmits the received heart rate information to a computer using RS232 serial communication. The computer will have a software that will display the heart rate information.

Experiments: Implementing a remote ZigBee monitoring systemEach end-device has a unique device address,

which is used to map heart rate information to a particular baby in the incubator room.

Ideally, heart rate sensor would be based on electrodes attached to a baby. An analog input on the Zigbee device would collect electric signals from the sensor and Analog-to-Digital converter would provide digital data.

In our experiment, we have used a random number generator on the Zigbee device to simulate baby’s heart rate.

An extension of this work would be to develop a software that transmits heart rate information to a central monitoring system over Ethernet LAN.

Reliability and Fail Safe measuresSince the heart rate is reported periodically,

the receiver /coordinator can detect if any node in the ZigBee network has failed (whatever be the reason).

The computer receiving periodic data from the receiver/coordinator, can detect if the receiver failed.

According to battery life (depends on battery), the software running on the computer attached to zigbee coordinator, can estimate if one of the zigbee nodes is going to die.

Hardware SpecificationCC2430 system on a chip with 8051

microcontroller, an RS232 interface, a USB Slave interface, an open A/D converter line plus an integrated accelerometer, light sensor, LEDs, a joystick and buttons.

CC2430 System-on-Chip (SoC) is specifically tailored for IEEE 802.15.4 and ZigBee™ applications. Combined with the industry leading ZigBee™ protocol stack (Z-Stack) the CC2430 provides the market’s most competitive ZigBee™ solution.

CC2430 Development Board

SmartRF04EB (Evaluation Board)

Zigbee Network used for experimentation Picture below shows the Zigbee network we used for the project. The coordinator is the board with

the serial cable attached to it. The end devices/nodes are the other three devices.

ZigBee communication (Packet Sniffer)

Color Code in Packet Sniffer

ZigBee channel selectionThe 802.15.4 specification defines 16 channels in the 2.4 GHz frequency range. These channelsare assigned numbers 11 through 26. Z-Stack initially defaults to channel 11, but the user can select a different channel by changing DEFAULT_CHANLIST. This parameter is a bit map field,with each bit representing a single channel. As shown below, the initial default channel 11 (0xB)is represented by 0x00000800 (11th bit in the field, starting from bit 0).

IAR Embedded Workbench

Application Layer

Z-Stack

ConclusionWe have proposed a low-cost solution to

enhance the remote monitoring capability of existing health care system.

We conducted a feasibility study of using ZigBee network based heart rate monitoring system.

It is secure, robust and low-power consuming.It can operate on multiple channels so as to

avoid interference with other wireless devices or equipments in the hospital.