Hybrid peak to average power ratio reduction in orthogonal frequency division multiplexing system

Abstract

Multi-carrier systems based on Orthogonal Frequency Division Multiplexing (OFDM) is a widely-used modulation in wireless communication systems because it enables high throughput data transfer and is robust against frequency selective fading caused by the multipath wireless channel. Nevertheless, OFDM suffers from disadvantages such as high Peak-to-Average Power Ratio (PAPR) and high sensitivity to Carrier Frequency Offset (CFO) which leads to a loss of subcarrier orthogonality and severe system degradation. Thus, a suitable reduction technique should be used in OFDM system to mitigate these drawbacks. Mitigation of the impacts of PAPR and Inter-Carrier Interference (ICI) due to CFO at the OFDM transmitter is the main target of this work. In this work, PAPR and ICI reduction methods are proposed at the OFDM transmitter. Clipping Peaks Amplifying Bottoms (CPAB) method is developed to reduce PAPR, where the negative peaks of the clipped OFDM signal are amplified. However, to reduce further PAPR level, a combination of Partial Transmit Sequence (PTS) with Cascade CPAB (PTS-CCPAB) is proposed. To improve BER performance, a Carrier Frequency Offset (CFO) compensation method is added to the hybrid PTS-CCPAB. The proposed work was conducted in MATLAB simulator using the parameters of Wireless Access Vehicular Environment (WAVE) IEEE 802.11p standard. The hybrid PTS-CCPAB/CFO introduced a PAPR Reduction Gain (RG) of 39% compared to the conventional system. Also, system performance at BER =10-4 improved by 12% and 5% over Additive White Gaussian Channel (AWGN) and Rayleigh channels respectively compared to the conventional system. Overall results show that the proposed work is a suitable solution to mitigate the loss of subcarrier orthogonality and system degradation by improving both PAPR and BER performances. The proposed work can be used in most multicarrier wireless communication system.