Exponential Companding Transform to Mitigate PAPR in SC-FDMA Systems

Abstract

Long Term Evolution (LTE) chose Single Carrier Frequency Division Multiple Access (SC-FDMA) for uplink communications due to lower signal envelope changes in SC-FDMA signal. This enables low peak to average power ratio (PAPR) in SC-FDMA in contrast to Orthogonal Frequency Division Multiple Access (OFDMA). High PAPR cannot be ignored as it reduces energy efficiency due to the requirement of large range linear power amplifiers. As the mobile devices are power restricted, there is a requirement to mitigate PAPR in the uplink SC-FDMA systems, especially for higher order modulations. Companding is an attractive technique to mitigate PAPR without any bandwidth extension. This paper suggests a companding transform using exponential function to mitigate PAPR in SC-FDMA systems. The suggested transform maintains the average signal power contrary to $\mu$ law companding. Simulation results demonstrate that exponential companding technique without any decompanding operation reduces PAPR by a significant value by maintaining the average signal power and BER performance.