A Suboptimal Tone Reservation Algorithm Based on Cross-Entropy Method for PAPR Reduction in OFDM Systems

This paper considers the use of the tone reservation (TR) technique to reduce the peak-to-average power ratio (PAPR) of an orthogonal frequency division multiplexing (OFDM) signal. In the TR scheme, a small number of unused subcarriers called peak reduction carriers (PRCs) are reserved to reduce the PAPR and the goal of the TR scheme is to find the optimal values of the PRCs that minimize the PAPR of the transmitted OFDM signal. Although the TR optimization problem is convex, finding the exact solution to this problem requires a computationally expensive task, which is a potential problem for its practical implementation. To address this problem, the cross-entropy (CE) method is introduced to determine sub-optimum values of the PRCs with low complexity. Compared with the conventional the conventional genetic algorithm (GA)-based TR method, the simulation results show that the proposed CE-assisted TR scheme provides a better PAPR reduction performance and achieves the PAPR values below the predefined various thresholds.