PAPR reduction in OFDM system using combined MCS and DHMT precoding

Mohd Danial Rozaini,Azlina Idris,Darmawaty Mohd Ali,Ezmin Abdullah

doi:10.11591/ijeei.v8i4.1767

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) has become a preferable scheme for most high data rate wireless communication standards. However, the non-linear power amplifier effect experienced in the OFDM system has increases the peak-to-average power ratio (PAPR). This paper proposed a Median Codeword Shift (MCS) as a new solution to alleviate the effect of high PAPR. MCS takes advantage of the codeword structure and bit position changes through the manipulation of the codeword structure and permutation process to achieve a low PAPR value. Additionally, the enhanced version of MCS is also being proposed by merging MCS with the Discrete Hartley matrix transform (DHMT) precoding method to boost the PAPR reduction. Simulation results show that MCS is capable of minimizing PAPR of conventional OFDM with 24% improvement and at the same time outperform Selective Codeword Shift (SCS) with a 0.5 dB gap. A remarkable result was also achieved by MCS-DHMT with a 15.1% improvement without facing any bit error rate (BER) degradation.

Highlights

Orthogonal Frequency Division Multiplexing (OFDM) is a well-known multicarrier modulation technique that has become the fundamental technology for the generation of wireless communication systems
Throughout this section, the performance of Median Codeword Shift (MCS) and MCS-Discrete Hartley matrix transform (DHMT) will be evaluated in terms of peak-to-average power ratio (PAPR) reduction and bit error rate (BER) degradation by using MATLAB
The simulation results reveal that MCS has successfully reduced the PAPR value of the OFDM system by 2.6 dB which is equivalent to 24% improvement while SLM with 6 different phase sequence and Selective Codeword Shift (SCS) manages to reduce the PAPR value by 1.1 dB (10.5% improvement) and 2.1 dB (19.2% improvement) respectively

Summary

INTRODUCTION

Orthogonal Frequency Division Multiplexing (OFDM) is a well-known multicarrier modulation technique that has become the fundamental technology for the generation of wireless communication systems. Selective codeword shift (SCS) is one of the methods that take advantage of bit positioning of a codeward to reduce the PAPR through the shifting process without altering the codeword structure itself. The shifting process enables SCS to generate an alternative codeword in which the lowest PAPR among the alternative codeword will be selected for transmission. This method is better in terms of PAPR reduction and computational complexity compared to SLM and DPP. A new method is proposed to counteract the high PAPR problem in the OFDM system namely Median Codeword Shift (MCS). MCS achieves a significant reduction in PAPR without degrading the bit error performance (BER) of the system compared to SCS.

OFDM SYSTEM MODEL AND PAPR

RESULTS AND DISCUSSION

CONCLUSION