A Low-Complexity PAPR Reduction Scheme for Multi-User MIMO-OFDM Systems

Multi-user multiple-input multiple-output orthogonal frequency division multiplexing (MU-MIMO-OFDM) is an attractive technique for high-data-rate transmission. However, one main disadvantage of the MU-MIMO-OFDM system is the high peak-to-average power ratio (PAPR), which causes inefficient power amplifier utilization and limits the transmit power. To address this issue, some effective PAPR reduction schemes, such as the conventional active constellation extension (ACE), can be applied for the MU-MIMO-OFDM systems, which limits the maximum amplitude of the signals by iteratively modifying the signal constellation. However, the iterative signal processing procedures induce excessive computation complexity and delay, which is prohibited in high data rate communications. In this paper, we propose a low-complexity PAPR reduction method, where an improved tone reservation (ITR) scheme based on least square approximation (LSA) is first performed, and then the modified ACE scheme is appiled to further decrease the PAPR. Compared to the conventional ACE scheme, simulation results show that the proposed method significantly reduces computational complexity without sacrificing BER, and achieves better PAPR.