A Unitary Precoder for Optimizing Spectrum and PAPR Characteristic of OFDMA Signal

In this paper, a unitary precoder is proposed to suppress the out-of-subband (OOSB) spectral leakage and reduce the peak-to-average-power-ratio (PAPR) for DFT-based orthogonal frequency division multiple access uplink signal. The optimum precoder is developed by solving a multi-objective optimization problem and a method which includes two steps is presented. First, employ eigenvalue decomposition to design the precoder with minimizing OOSB power radiation. Then search for the optimum permutation of columns to reduce the PAPR sufficiently. Besides, an iterative decoding algorithm for the proposed precoder is designed to improve the system performance on bit-error-rate (BER). Simulations show that the proposed precoding and decoding method offers significant performance advantages of spectral leakage suppression, PAPR reduction, and BER improvement at the same time.