Improvement of peak and average power reduction of trellis shaped OFDM signals by controllable region expansion

Orthogonal frequency-division multiplexing (OFDM) is known for its excellent bandwidth efficiency and robustness against multi-path fading channels. The major drawback of OFDM is its high peak-to-average power ratio (PAPR) property that substantially reduces the power conversion efficiency of power amplifiers (PA). Trellis shaping (TS) is known as one of the effective methods to reduce peak power as well as average power of OFDM signals and its reduction capability depends on the number of regions in the quadrature amplitude modulation (QAM) constellations that are selectable by the shaping bits. In this paper, we propose a method to considerably improve the peak and average power reduction capability of trellis shaped OFDM by expanding the controllable regions for a given QAM constellation. The effectiveness of the proposed approach is confirmed by simulations in terms of PAPR and average power reduction capabilities as well as its bit error rate performance and PA efficiency under the scenario of a linear PA model.