HYBRID PEAK TO AVERAGE POWER RATIO REDUCTION TECHNIQUE IN ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) is a multicarrier modulation (MCM) technique that plays a significant role in digital wireless communication. This is due to its ability to provide a high data rate for new multimedia applications. One of the major drawbacks of OFDM is the high peak-to-average power ratio (PAPR) which is characteristic of signals with multiple sub-carriers. The high PAPR requires additional back-off power to achieve linear amplification at the transmitter end which results in inefficient power consumption. This inefficient power consumption is the major problem in implementing OFDM in a portable device. Nevertheless, several PAPR reduction techniques have been proposed in the past to address this problem. However, all techniques previously used to reduce PAPR suffer due to various deficiencies such as data rate loss, high signal distortion, increase in bandwidth, high computational complexity, increase in transmit power and memory requirements. Therefore, this research aimed at reducing the peak to average power in the OFDM system by hybridizing Zadoff-Chu Transform (ZCT) precoding and Partial Transmit Sequence (PTS) techniques. The methodology employed to reduce high PAPR in this work is based on developing an OFDM model with Additive White Gaussian Noise (AWGN) and implementing the hybridized PAPR reduction technique combining ZCT precoding and PTS. The performance evaluation of the hybrid model is carried out using the Complementary Cumulative Distribution Function (CCDF), Bit Error Rate (BER), and Power Spectral Density (PSD). The results obtained show that each technique can efficiently reduce PAPR with ZCT having 4.8 dB PAPR which is about 6 dB reduction from Original OFDM PAPR while PTS with a larger number of subblocks (V = 8) has about 6.44 dB reduction from Original OFDM with about 4.4dB PAPR. The new hybrid technique achieved a better PAPR of 4.2 dB and better overall system performance when compared with the individual performance of ZCT and PTS. The hybrid ZCTPTS method has a low PSD of -58 dB/MHz using subblocks 4 at N = 64 as compared with the original OFDM which has a PSD of -53dB/MHz. The result shows that the new hybrid technique is efficient and the problem of high PAPR in the OFDM system that causes power deficiency is mitigated. Finally, the technique can be adopted as a PAPR reduction method in mobile communication as mobile communication requires a low PAPR technique with low computational complexity.