A DFT-Aided PAPR-Aware Cyclic Shift and Phase Selection Scheme for GFB-OFDM

Abstract

Generalized filter bank orthogonal frequency division multiplexing (GFB-OFDM) has advantages such as multi-subband processing and low out-of-band radiation, and shows promise for future 6G-oriented space-air-ground integrated communications. However, GFB-OFDM still suffers from a high peak-to-average power ratio (PAPR). Although the existing two-stage DFT precoding method can reduce the PAPR, multi-subband processing and misaligned superposition may still produce residual peaks in the final time-domain signal. To address this issue, this letter proposes a DFT-aided PAPR-aware cyclic-shift and phase joint selection (DFT-PCPS) method. By introducing cyclic-shift candidates to the subband sequences after the first-stage DFT precoding and jointly selecting unit-modulus phase factors, the proposed method suppresses the residual peaks caused by coherent subband superposition. Simulation results show that the proposed DFT-PCPS can effectively reduce the residual PAPR of GFB-OFDM while maintaining the BER performance, and the additional complexity is acceptable relative to the obtained PAPR gain.