Minimization of OFDM Clipped Samples Power by Tone Reservation Algorithm

Abstract:
Nonlinear distortion of a signal at a nonlinear Power Amplifier (PA) is a serious problem preventing Orthogonal Frequency Division Multiplexing (OFDM) systems from achieving high energy-efficiency. This paper addresses this issue by proposing Clipping-Aware Tone Reservation (CA-TR) method. It minimizes cumulative power of all samples exceeding a given clipping threshold in contrast to typically used maximal peak power minimization techniques. Convex optimization function is defined and solved using Newton’s method followed by line search algorithm. Low computational complexity of the solution is achieved by utilization of Fast Fourier Transform (FFT) blocks. Simulation results confirm this approach is advantageous over typically used Peak-to-Average Power Ratio (PAPR) minimization in terms of Signal-to-Distortion Ratio (SDR).