Biomedical Engineering Reference
In-Depth Information
Start of time slot
Clock
Synchronisation
Preamble
detection
Threshold below
noise level
Reason ?
No
Success?
High BER
Yes
Increase threshold
by one step
BER compensation
Data detection
Fig. 6.7
Overall operation of data detection
duration of 1 ms is used for all the sensor communications. Continuous sensors
transmit in Guaranteed Time Slots (GTS) with a duration of 100 ls, while periodic
sensors transmit during Contention Access Period (CAP) within a time slot
duration of 50 ls. Figure
6.8
depicts a decoded bit stream by the FPGA module
using the data detection methodology described above.
6.5 A WBAN Implementation: Multi Sensor ECG
and Temperature Monitoring System
A multi sensor ECG and temperature monitoring system is set up in order to
demonstrate the overall operation of the MAC protocol [
8
]. Three sensor nodes are
used for ECG monitoring while one sensor node is used for the periodic tem-
perature monitoring. Sensor nodes that transmit ECG data use GTS for continuous
data transmission while the sensor node that transmits temperature data uses CAP
for periodic data transmission. The period of data transmission for the temperature
sensor is chosen to be 10 s. All the sensor nodes are placed on-body of a single
user while the coordinator node is placed outside the body. Distance between body
and receiver antenna is kept at 70 cm for the demonstrated experimental set up.
