FFT-Free PAPR Reduction Methods for OFDM Signals

In this paper, we propose two low-complexity peak to average power ratio(PAPR) reduction algorithms for orthogonal frequency division multiplexing(OFDM) signals. The main content is as follows: First, a non-convex optimization model is established by minimizing the signal distortion power. Then, a customized alternating direction method of multipliers(ADMM) algorithm is proposed to solve the problem, named time domain ADMM(T-ADMM) along with an improved version called T-ADMM with constrain update(TCU-ADMM). In the algorithms, all subproblems can be solved analytically, and each iteration has linear computational complexity. These algorithms circumvents the challenges posed by repeated fast Fourier transform(FFT) and inverse FFT(IFFT) operations in traditional PAPR reduction algorithms. Additionally, we prove that the T-ADMM algorithm is theoretically guaranteed convergent if proper parameter is chosen. Finally, simulation results demonstrate the effectiveness of the proposed methods.