Biomedical Engineering Reference
In-Depth Information
Hence, an IR-UWB transmission system is capable of achieving higher data rates
while operating at low power, which makes it an ideal candidate for power
intensive WBAN applications that demand high data rates, such as wireless cap-
sule endoscopy systems [
28
,
29
] and neural recording systems [
6
].
(3) Small form factor
Small size is an essential property for implantable and wearable WBAN sensor
nodes. IR-UWB transmitters can be manufactured with only a few electronic
components: hence the design space required is minimal. This is an advantageous
property that makes IR-UWB a suitable candidate for WBAN sensor nodes.
(4) Susceptibility to multipath interference
IR-UWB uses finite resolution pulses in order to represent data bits. Unlike in
the case of continuous wave signals where multipath components always overlap
with time domain signals at the receiver end, the multipath arrivals of the IR-UWB
signals can be easily resolved and avoided at the receiver end because of the low
probability of a multipath component overlapping with the received narrow pulse
in the time domain [
30
,
31
]. This is a very useful feature in IR-UWB when it is
operating around the body where the presence of multipath components can be
high.
In spite of these advantages, there are some drawbacks in IR-UWB technology
that should be overcome for WBAN applications. These disadvantages are listed
below:
(1) Complexity of the IR-UWB receiver architecture
IR-UWB signals use narrow pulses to transmit data and the transmitted signal
power is regulated to be very low in order to prevent interference to other systems.
An IR-UWB receiver has to be capable of detecting these low power narrow
pulses. This requires the use of high speed Analog to Digital Converters (ADC)
and extensive amplification of the received signals at IR-UWB receiver front-end.
This makes the IR-UWB receiver to be complex in design and results in increased
power consumption. This is a major drawback in IR-UWB systems that should be
overcome in order to use IR-UWB for power intensive WBAN applications.
(2) Susceptibility to interference from other wireless transmission systems
Unlike in the case of carrier based systems, IR-UWB signal power is spread
across a wide bandwidth. Hence it is susceptible to interference from all the systems
operating within the IR-UWB signal bandwidth. The signal processing involved in
the reception of carrier based signals has to consider only the interference rejection
in that particular carrier frequency, whereas for IR-UWB systems, the signal pro-
cessing at the receiver end should consider interference mitigation for the whole
signal bandwidth. This problem can be overcome by choosing a suitable operational
bandwidth with minimum interference for IR-UWB communication. Figure
1.4
