Reduction of PAPR in OFDM using Hybrid SLM-Companding for future Wireless Communications

Abstract

The demand for Orthogonal Frequency Division Multiplexing (OFDM) in wireless networks increases due to the advantages like efficient bandwidth utilization and the simple structure of equalizer. High Peak to Average Power Ratio (PAPR) in OFDM signal leads to lowering of efficiency in High Power Amplifier (HPA). Different approaches were proposed in the literature to reduce the PAPR in OFDM. One among them is Companding which reduces Spectral leakage. The second one is Selected Mapping (SLM) which increases the system performance by reducing the Bit Error Rate (BER). Both the methods are used in practice to reduce the PAPR by a considerable amount. Hence in this paper, the combination of both SLM and Companding techniques are considered which is termed as Hybrid method. The nonlinear companding techniques like Rooting Companding Technique (RCT) and Cosine companding (COS) minimize the PAPR to 4.7 dB and 3.5 dB respectively compared to conventional OFDM signal’s PAPR when they are combined with SLM technique. As the results are encouraging, these techniques can be used in future wireless communication systems.