Biomedical Engineering Reference
In-Depth Information
Power
Management
(1-3V)
Battery
Amplifier/
Filter
A/F
Antenna
ADC
Micro-
controller
MUX
Radio
Transceiver
A/F
Fig. 5.1
An example of sensor node design for WBAN [
1
]
Bandpass
Filter
(3.5-4.5GHz)
Amplifier
(3.5-4.5GHz)
UWB Pulse
generator
Data
Interface
electornics
(INA321)
Micro-
controller
PIC18F14K22
Fig. 5.2
A transmit-only IR-UWB sensor node design [
2
-
4
]
antenna, this unit provides the wireless capability for a sensor node. In wireless
sensor network applications, transceiver uses a signal band for both transmitting
data and receiving data. Figure
5.2
shows the block diagram of an IR-UWB sensor
node that does not contain any receiver [
2
-
4
]. This design uses a transmit-only
approach to transfer data from sensor nodes to a central coordinator node.
The body area network sensor node presented in this chapter is battery powered
and consists of an IR-UWB transmitter, a 433 MHz Industrial, Scientific and
Medical (ISM) band receiver, an analog interface circuit and a micro-controller
module [
5
,
6
]. The use of an ISM band receiver eradicates the requirement of a
complex UWB receiver at the sensor node, hence greatly reduces the power con-
sumption as well as the design complexity of the sensor node. IR-UWB pulse gen-
erator and IR-UWB RF section lies at the core of the sensor node. This chapter
analyses various physical layer properties of IR-UWB signals, such as pulse width,
Pulse Repetition Frequency (PRF), and rise/fall times of pulses in order to design an
IR-UWB pulse generator with a less complex hardware implementation and
enhanced performance. IR-UWB RF section is developed based on an up-conversion
based hardware architecture, where base band pulses are up-converted using a mixer
in order to utilize the higher power contained within the lower half of the frequency
spectrum that belongs to the base band pulse stream generated by the IR-UWB pulse
generator. Hardware design techniques that are followed when integrating a trans-
mitter that operates in UWB frequencies (3.5-4.5 GHz) and a receiver that operates
