Metric-based PRT set selection in tone reservation scheme for PAPR reduction in OFDM systmes

High peak-to-average power ratio (PAPR) is one of the main problems of orthogonal frequency division multiplexing (OFDM) systems. Tone reservation (TR) scheme employs a subset of reserved subcarriers to construct a cancellation signal for PAPR reduction, with no additional distortion, no side information, and low implementation cost. Thus, the optimal performance of TR scheme depends on the selection of the peak reduction tone (PRT) set. In the conventional TR schemes, we have known that PAPR reduction performance achieved by a randomly generated PRT set is superior to that by a consecutive PRT set and that achieved by an interleaved tone set. However, the search of optimal PRT set is a nondeterministic polynomial-time (NP)-hard problem and cannot be solved. In this paper, a metric-based PRT set selection algorithm is presented to provide good performance and fast convergence. The scheme employs a metric to measure how much each subcarrier contributes to the output signal samples of large magnitude and then subcarriers with the largest positive metrics are selected as PRT set for PAPR reduction. The simulation results show that when the reserved subcarriers number is 1.46 percent, the PAPR gain of the proposed method can achieve 0.74dB at least compared with the conventional TR schemes at the probability of 10⁻³.