An ADMM Approach for PAPR Reduction for Large-Scale MIMO-OFDM Systems

We consider the problem of peak-to-average power ratio (PAPR) reduction for orthogonal frequency-division multiplexing based large-scale multiple-input multiple-output systems. A novel perturbation-assisted scheme is developed to reduce the PAPRs of the transmitted signals by exploiting the redundant degrees-of-freedom inherent in the large-scale antenna array. Specifically, we introduce carefully devised perturbation signals to the frequency-domain precoded signals, with the aim of reducing the PAPRs of their time-domain counterpart signals. Meanwhile, the additive perturbation signal associated with each tone is constrained to lie in the null-space of its associated channel matrix, such that it does not cause any multiuser interference and out-of-band radiations. Such a problem is formulated as convex optimization problems, and two efficient algorithms, referred to as PROXINF-ADMM1 and PROXINF-ADMM2, are developed by resorting to the variable splitting and alterative direction method of multipliers techniques. Simulation results show that the proposed method has a fast convergence rate and achieves substantial PAPR reduction within only tens of iterations.