Minimizing PAPR of OFDM Signal Using Discrete Cosine Transform and Log Companding

• Published in: International journal of advanced networking and applications 2022-09, Vol.14 (2), p.5361-5366
• Main Authors: Odukwe, P C, Mbachu, C B, Ekengwu, B O, Onebunne, D K
• Format: Article
• Language: English
• Subjects: Algorithms; Companding; Discrete cosine transform; Genetic algorithms; Optimization; Simulation
• ISSN: 0975-0282; 0975-0290; 0975-0282
• DOI: 10.35444/IJANA.2022.14206

This paper proposed precoding of OFDM signal using Discrete Cosine Transform (DCT) and adding of Log companding algorithm so as to reduce PAPR. Three scenarios were considered to fully examine the effect of PAPR in OFDM system based on simulations conducted in MATLAB environment while varying the number of subcarriers, N = 64 and 256. Initial simulation using conventional OFDM showed high PAPR in transmitted signal for N = 64 and 256, which resulted in PAPR of 9.741 and 11.41 dB respectively. In the second case, log companding technique was introduced into the OFDM and it was observed that PAPR was significantly reduced to 5.664 dB, and 6.101 dB by a percentage improvement of 41.9% and 46.5% for N = 64 and 256. For the proposed scheme, DCT scheme was used to initially precode the OFDM and a log companding algorithm applied, the results obtained indicated more than half level of reduction in PAPR of OFDM signal such that for N = 64 and 256 the PAPR was reduced to 4.214 dB and 4.743 dB, which corresponded to percentage improvement of 56.7% and 58.4% respectively.