Hardware Architectures for IR-UWB-Based Transceivers - Ultra Wideband Wireless Body Area Networks - page 74

,

r (t)

( ) 2 ∫

LNA VGA Detector

Fig. 4.5 An energy detection non-coherent UWB receiver

Integrator Thresholder

Multiplier

Filter

∫

Delay

Fig. 4.6 An autocorrelation non-coherent UWB receiver

AcR receivers use a delay path and a multiplier circuit instead of the squarer
circuit in the energy detection receiver. The operation of AcR receivers is based on
the use of a reference pulse that is transmitted by the transmitter in order to
correlate with the data modulated pulses that follow the reference pulse. The
reference pulse that is transmitted prior to every data modulated pulse is delayed
using a delay line, and is used as the signal template for the data reception that
follows. The channel information embedded in the reference pulse improves the
performance of the receiver by reducing the Inter Symbol Interference (ISI). Basic
diagram of an AcR receiver is shown in Fig. 4.6 . Performance of AcR receivers is
discussed in [ 21 , 22 ]. The main drawback of an AcR receiver is the requirement of
a precise delay line. It also suffers from performance deterioration due to the use of
a noisy template.
The BER performance of both the ED and the AcR receivers depend on the
integration window time, which determines the amount of signal energy gathered
during the integration period [ 18 ]. Further, it has shown in [ 18 ] that the ED
receiver outperforms the AcR receiver in terms of BER for OOK and Binary Pulse
Position Modulation (BPPM) schemes. Results in [ 23 ] demonstrates that the ED
receiver is more power efficient than the AcR receiver.