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Tone Reservation to Minimize Nonlinearity Impact on OFDM Signals

To enhance the power efficiency of high-power amplifiers (HPAs) with the demand of reducing energy consumption, a tone reservation (TR) technique is adopted to make orthogonal frequency-division multiplexing (OFDM) signals less sensitive to nonlinearity of HPAs. In this paper, we attempt to minimize the sensitivity from the point of signal-to-noise ratio (SNR) loss at the receiver. Specifically, the nonlinearity impact on OFDM signals is evaluated by a normalized correlation coefficient (NCC) of amplifier input and output signals. With the introduction of the NCC, we model the design of TR as an optimization problem and propose an adaptive-scaling-based gradient-project approach. Simulation results show that, in terms of bit error rate (BER) and power spectral density (PSD) performance, our proposed approach is superior to conventional schemes.