PAPR reduction for beamforming OFDM via constellation-beam modification

The high peak-to-average power ratio (PAPR) of orthogonal frequency multiplexing (OFDM) greatly reduces the transmitter power efficiency. We propose a method that yields significant and consistent PAPR reductions for all numbers of users (receivers) in a beamforming MISO-OFDM system, such as WiMAX, by simultaneously exploiting the degrees of freedom in the constellation domain and in the null-space of the channel matrix. We also provide an efficient algorithm that is compatible with various constellation configurations in practical systems. With no sacrifice in data rate or channel efficiency, the proposed method achieves a maximum of 6.59 dB and a minimum of 2.11 dB PAPR reduction in an 8-antenna QPSK beamforming MISO-OFDM scenario.