PAPR Reduction in MIMO-OFDM via Power Efficient Transmit Waveform Shaping

Abstract

In this paper we revisit the long-standing problem of peak-to-average power ratio minimization in MIMO-OFDM systems, with a new angle of approach on a well-known scheme. Utilizing the principles of tone reservation, we place dummy symbols, i.e., complex coefficients, on unused space-frequency resources with the aim of jointly minimizing the transmit signal PAPR and the self-power consumption of the dummy symbols. To solve this joint minimization, we propose three different algorithms exhibiting varying degrees of computational complexity and PAPR reduction performance. Our proposed framework utilizes the strict PAPR expression, i.e., we take into account the average transmit power of the antenna, to simultaneously reduce the PAPR on all antennas while keeping the self-power consumption of the scheme minimal. Our simulation results show that this optimization objective provides better worst-case PAPR reduction and dummy symbol power consumption performance compared to the peak power minimization objective widely utilized in the tone reservation literature. Finally, we propose a novel take on a well-known block-diagonalization algorithm by exploiting knowledge on dummy symbol allocations, resulting in high-gain data streams in downlink transmission.

Keywords

• ADMM
• alternating directions method of multipliers
• convex optimization
• low complexity
• MIMO-OFDM
• PAPR