PAPR Reduction for FBMC-OQAM System With Laplace-Based Linear Companding Transform

The filter-bank multi-carrier (FBMC) with offset quadrature amplitude modulation (OQAM) is considered a promising waveform for 5G due to its favorable frequency-time localization and efficient spectrum utilization. However, the specific overlapping structure and multi-carrier nature of FBMC-OQAM waveforms result in an exceptionally high peak-to-average power ratio (PAPR). To address this issue, this letter introduces a linear companding transform scheme tailored for FBMC-OQAM waveforms to reduce the PAPR. Since, the unique modulation technique leads to a high probability of extreme amplitude occurrences in the FBMC-OQAM waveform, with the amplitude's probability density function closely resembling a Laplace distribution rather than a Gaussian distribution. We derive the companding gain expression for the FBMC-OQAM signal and establish a parameter division criterion suitable for the FBMC-OQAM waveform under the assumption of a Laplace distribution. The simulation results reveal that while upholding optimal bit error rate performance, the proposed scheme provides at least 58% and 20% performance advantages in PAPR reduction capability compared to the Gaussian distribution-based linear nonsymmetrical transform and linear companding transform schemes, respectively.