A wide range of techniques have been proposed to
reduce the Peak-to-Average Power Ratio (PAPR) of Orthogonal
Frequency Division Multiplexing (OFDM) signals with different
trade-offs between PAPR reduction and Bit Error Rate (BER)
performance degradation. Usually these techniques are studied in
an uncoded context and over an ideal Additive White Gaussian
Noise (AWGN) channel, and a compromise between PAPR
and BER degradation is achieved depending on the adopted
constellation.
In this paper, we go further and compare several PAPR
reduction techniques for Quadrature Amplitude Modulation
(QAM) constellations under a typical coded OFDM scenario with
time-dispersive channels. Our results show that low complexity
techniques as clipping can have a good trade-off between PAPR
reduction and BER degradation close to the one of the best
techniques analyzed, even in a scenario with multipath timedispersive channel and for relatively large QAM constellations.
Once that is shown that clipping is a good choice for PAPR
reduction, it opens a subject in the study of PAPR reduction
techniques in order to improve its behavior. We also consider the
PAPR reduction as a constrained optimization problem which,
although too complex to solve, provides an approximate bound
on the achievable PAPR.