
48
Power effiCienCy in wireless CommuniCations
where τ=ττ
is the real-valued kth-order Volterra kernel,
and dτ
k
= dτ
1
... dτ
k
. A special case of the Volterra series is when the
power amplifier has short-term memory; on the other hand, the time
span of the memory is short compared to the time variations of the input
signal envelope. Raich and Zhou (2002) have shown that the baseband
version of Equation (3.40) has the same form as Equation (3.41) except
that a
k
are complex valued. Now the power amplifier has both ampli-
tude distortion and phase distortion to the input signal. However, the
baseband representation in this case is ...