  Orthogonal Frequency Division Multiplexing (OFDM) is widely used in many
digital communication systems due to its advantages such us high bit rate,
strong immunity to multipath and high spectral efficiency but it suffers a high
Peak-to-Average Power Ratio (PAPR) at the transmitted signal. It is very
important to deal with PAPR reduction in OFDM systems to avoid signal
degradation. Currently, the PAPR problem is an active area of research and in
this paper we present several techniques and that mathematically analyzed.
Moreover their advantages and disadvantages have been enumerated in order to
provide the readers the actual situation of the PAPR problem.
