Reducing the peak to average power ratio in 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 for wireless communications. However MIMO OFDM suffers from high PAPR, this demands expensive linear amplifiers with wide dynamic range. In MIMO OFDM systems, a straightforward way for PAPR reduction is to apply existing techniques separately on each transmit antenna, then the overall PAPR reduction is obtained. A proposed technique based on modified partial transmit sequences (PTS) using circular shifting and phase rotation is employed to achieve more reduction in the overall PAPR in MIMO OFDM, it exploits the extra degree of freedom provided by MIMO to reduce the overall PAPR. Two sub-optimal solutions for modified PTS are suggested, to reduce the complexity and side information in MIMO OFDM, with slight loss of PAPR reduction performance.