Tone Reservation Ratio Optimization for PAPR Reduction in OFDM Systems

Orthogonal frequency division multiplexing (OFDM) systems suffer from a large peak-to-average power ratio (PAPR), leading to lower power efficiency and nonlinear distortion at the transmit power amplifier. Tone reservation (TR) techniques can effectively reduce PAPR, but may also cause data rate reduction if the TR ratio is not carefully designed. In this paper, we propose a low-complexity TR approach for PAPR reduction in OFDM systems, which is parametrized by the TR ratio. Then, under certain approximations, we characterize the PAPR reduction and the data rate increase of the proposed TR approach using order statistics. Next, we formulate the TR ratio optimization problem to maximize the data rate. The optimization problem is very challenging, as the data rate cannot be explicitly expressed as a function of the TR ratio. To reduce the computation complexity, we propose a near optimal solution by solving an approximate optimization problem of the original one. Finally, numerical results verify the analysis and demonstrate the performance of the proposed near optimal solution.