Overall PAPR Reduction for MIMO OFDM Systems

Multiple Input Multiple Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) systems have been receiving a great attention as one of the solutions for achieving high speed, efficient, and high quality of service wireless communications. However, the main drawback of MIMO OFDM systems is high Peak to Average Power Ratio (PAPR) because of its sensitivity to the nonlinear distortions introduced by nonlinear devices. In MIMO OFDM systems, a straightforward way for PAPR reduction is to apply existing techniques separately on each transmit antenna. Therefore, a higher overall PAPR is obtained with increasing the number of transmit antennas. In this paper, Partial Transmit Sequences (PTS) technique is modified with different circular shifting approaches. They exploit the extra degree of freedom provided by the transmit antenna array to reduce the overall PAPR even with increasing the number of transmit antennas.