A new PAPR and BER enhancement technique based on lifting wavelet transform and selected mapping method for the next generation waveforms

Abstract

Orthogonal frequency division multiplexing (OFDM) is widely used in many digital communication systems because of its immunity to inter-symbol interference, high spectral efficiency and capability of handling multipath. Walsh-Hadamard transform (WHT) and discrete wavelet transform (DWT) have also been suggested in order to enhance the performances of multi-carrier wireless communication systems. In general, high peak-to-average power ratio (PAPR) is one of the biggest disadvantages of these systems and OFDM also has this disadvantage. Many techniques such as amplitude clipping and filtering, encoding, interleaving, tone reservation (TR), tone addition (TI), partial transmission sequence (PTS), and selected mapping (SLM) techniques have been proposed to reduce the high PAPR. Without any modification these techniques are useless due to the related symbol addition process. For this reason, we developed a new technique composed of Lifting wavelet transform (LWT) and SLM method in order to decrease the PAPR in multi-carrier systems. The performance of this new LWT-SLM scheme is measured by applying it to zero tail (ZT) discrete Fourier transform-spread OFDM (ZT DFT-s OFDM) and unique word OFDM (UW OFDM) waveforms, which are promising next generation waveforms. Simulation results show that, the ZT DFT-s OFDM system obtains the 3.3 dB PAPR gain and 0.8 dB better bit error rate (BER) performance compared to classical OFDM with proposed scheme without sacrificing BER performance.