PAPR reduction in WPDM and OFDM systems using an adaptive threshold companding scheme

Abstract

High peak-to-average power ratio (PAPR) of transmitted signals is a major drawback for multi-carrier modulation (MCM) systems such as orthogonal frequency division multiplexing (OFDM) and wavelet packet division multiplexing (WPDM). Companding transform is an efficient and simple method to reduce the PAPR for MCM systems. In this paper, a novel adaptive companding transform scheme is proposed to efficaciously reduce the Peak-to-Average Power Ratio of OFDM and WPDM signals. In this technique, only the signals, whose amplitudes are higher than the threshold, are compressed in the transmitter, adaptively. We propose a new formula for the threshold level and send the threshold value to the receiver as side information. Using a simple judgment process, the expanding operation based on the transmitted side information will be executed to the compressed signals in the receiver. Computer simulation results show that the adaptive threshold companding (ATC) scheme effectively improves the performance of PAPR by introducing a simple adaptive threshold judgment process.

Hybrid PAPR reduction technique for complex wavelet packet modulation system

“…Since wavelet transforms always concentrate energy on some given number of bases, we can introduce a threshold T and compare it with the energy of each orthogonal base. The thresholding function is given as [5]:…”

“…The average signal power must therefore be kept low to ensure that the transmitter amplifier operates in the linear region. Many proposals to has been presented to reduce the PAPR in WPM systems [2][3][4][5][6].…”

Peak-to-Average Power Ratio Reduction for Wavelet Packet Modulation Schemes via Basis Function Design

“…Lastly, the criterion for choosing the threshold value T is not defined in (Zhang, Yuan, & Zhao, 2005), and hence, may depend on the characteristics of the HPA. An alternative amplitude threshold based scheme called adaptive threshold companding transform is proposed in (Rostamzadeh, Vakily, & Moshfegh, 2008). Generally, the application of nonlinear companding transforms to multicarrier communication systems are very useful since these transforms yield good PAPR reduction capability with low implementation complexity (Jiang & Wu, 2008).…”

“…Generally, the application of nonlinear companding transforms to multicarrier communication systems are very useful since these transforms yield good PAPR reduction capability with low implementation complexity (Jiang & Wu, 2008). In the adaptive threshold companding scheme proposed (Rostamzadeh, Vakily, & Moshfegh, 2008), signal samples with amplitudes higher than a threshold T are compressed at the transmitter via a nonlinear companding function; the signal samples with amplitudes below T are unaltered. To undo the nonlinear companding transform, received signal samples corresponding to signal samples that underwent compression at the transmitter are nonlinearly expanded at the receiver.…”

PAPR Reduction Schemes for Lifting Scheme based Orthogonal Wavelet Packet Multiplexing System

“…Some studies [8] and [9] present the method of probability to reduce PAPR, not only to affect the BER performance of system but to have high complexity, such as PTS technology. Methods of pre distortion [10] and [11], which implement nonlinear transform to the demodulated signals to decrease PAPR such as the method of µ-law companding transform are also studied.…”