Biomedical Engineering Reference
In-Depth Information
Table 1.2
Candidate wireless technologies for WBAN communication
Properties
Wireless technology
Zigbee
WLAN
MICS
Bluetooth
UWB
Frequency
2.4 GHz
2.4 GHz
5 GHz
401-406 MHz
2.4 GHz
3.1-10.6 GHz
Transmit
power
0 dBm
10-30 dBm
10-30 dBm
-16 dBm
0 dBm
-41.3 dBm/
MHz
Number of
channels
16
13
23
10
10
_
Channel
bandwidth
2 MHz
22 MHz
20 or
40 MHz
300 kHz
1 MHz
C500 MHz
Data rate
250 kbps
11 Mbps
54 Mbps
200-800 kbps
1 Mbps
850 kbps up to
20 Mbps
Range
0-10 m
0-100 m
0-100 m
0-10 m
0-10 m
2 m
Oxide Semiconductor (CMOS) based Integrated Circuit (IC) transceiver with the
lowest power consumption based on the MICS and 433 MHz ISM bands for
WBAN applications. This IC is used in the Given Imaging's PillCam WCE devices
for low power narrow band based implant communication [
34
]. The MICA2DOT
sensor platform provides a full hardware implementation on a small sensor plat-
form. However, the power consumption of the transmitter is considerably high
compared to that of the Microsemi's narrow band system. An implementation of a
small wearable pulse wave monitoring system that uses a Bluetooth based trans-
ceiver is presented in [
35
]. The total current consumption of the systems is esti-
mated to be 51 mA, inclusive of the current consumption of the Bluetooth
transceiver, which is estimated to be 21 mA with an operating voltage of 3.3 V. The
power consumption in a Zigbee and 2.4 GHz ISM band based sensor nodes are
considerably high compared to other sensor node designs. The comparison in
Table
1.3
shows that the if a sensor node is designed based on UWB utilizing
mainly a transmitter and minimizing/eliminating the use of a receiver, it will per-
form better than the narrowband based systems in terms of power consumption,
form factor and data rate.
It can be concluded that the UWB presents some unique benefits over other
wireless technologies in the design of WBAN sensor nodes including the low
power requirements of UWB transmitter, high data rate capability, low form factor
and reasonably uncomplicated circuit design. In terms of interference rejection,
UWB spectrum provides a large bandwidth; hence, a sub-band of UWB can be
selected for a particular application such that the interference from other bands is
minimized. Furthermore, IR-UWB is preferred over MC-UWB because of the
possibility of low complexity and low power consuming hardware implementa-
tion. IR-UWB is referred to as UWB in the remainder of this topic unless men-
tioned otherwise.
