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position modulation (PPM) schemes. However,
OOK requires a careful choice of the detection
threshold (Stoica 2008).
Typically, there is a common tradeoff between
the bit-error-rate (BER) performance and receiver
complexity. The implementation approaches
proposed in the literature for UWB systems
include, all-digital, analog, and partially analog
implementations (Sangyoub 2002; Verhelst and
al. 2006). In the all-digital implementation ap-
proach, the complexity is directly related to the
sampling frequency. High sampling frequencies
put limitations on the analog-to-digital (ADC)
design including speed and power consump-
tion, which is a very challenging task for UWB
systems based on the direct sampling approach.
Generally, due to the bandwidth requirements
of UWB signals, analog UWB receiver designs
are considered as they can accommodate for the
bandwidth requirements, which comes at the
expense of reduced flexibility. Whereas, the use
of digital approaches provide flexibility in the
receiver signal processing, but they are limited by
the ADC and digital-to-analog (DAC) resolution
and power consumption (Verhelst and al. 2006).
patient-health-data in real-time (Jovanov 2005).
However, it is not restricted to medical applica-
tions. Initial requirements of the BANs include
a coverage distance of 2 to 5m with a power
consumption of about 1 mW/Mbps at a distance
of 1m (Bindra 2008). Furthermore, for on-body
sensors, considered power technologies include
temperature difference, non-rechargeable (Zinc-
air, Lithium and silver-oxide) and Lithium-ion
rechargeable. Essentially, the low-power con-
sumption for on-body communications is required
to protect the human tissue (Jovanov 2005; Bindra
2008). The medical application proposals for
the BANs include swallowable devices for drug
delivery and imaging, wearable sensors, such as
electroencephalogram (EEG), electrocardiogram
(ECG), blood pressure, body temperature, and
hearing aids (Bin, Huan-Bang et al. 2007).
In IR-UWB receivers, the ADC can be moved
almost up to the antenna after the low-noise
amplifier (LNA), which moves the signal pro-
cessing to the digital domain, which is known as
the all-digital signal processing approach (Reed
2005; Verhelst and al. 2006; Ryckaert, Verhelst
et al. 2007). This approach puts high constraints
on the ADC, where to efficiently sample the
incoming signal at the Nyquist rate the sampling
frequency is of several gigahertzes. In this ap-
proach, the ADC speed and resolution become
of utmost importance (Verhelst, Vereecken et al.
2004; Verhelst and al. 2006; Ryckaert, Verhelst
et al. 2007). Baseband Nyquist sampling of a 2
GHz UWB signal requires approximately 4 GHz
ADC clocking, which has the potential to consume
enormous amounts of power. In particular, using
a figure of merit (FoM) of approximately 4e11,
the estimated power consumption of a 4 bit and
4 GSa/s ADC is equal to 160 mW. Whereas, a
key advantage of UWB radios is the low-power
consumption. The ADCs and the matched filters,
for coherent detectors, represent the bottleneck for
achieving a low-power consumption, where they
require high sampling rates (Verhelst, Vereecken
et al. 2004; Verhelst and al. 2006). Moreover, for
Power Consumption Requirements
of UWB Wearable WBANs
Wearable and implanted healthcare applications
have strict power consumption requirements,
where devices are directly attached to the sub-
ject's body. In particular, the IEEE has recently
approved the IEEE 802.15 TG6 task group for the
standardization of body area networks for short-
range, wireless communication in the vicinity of,
or inside the human body for the frequency bands
approved by the national medical and regulatory
authorities including the 3.1 - 10.6 GHz UWB
band (Bin, Huan-Bang et al. 2007; Bindra 2008;
Yazdandoost 2008). More specifically, the goal
of this group is to standardize short-range com-
munications via implanted medical devices and
on-body sensors with monitoring tools to provide
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