Peak reduction for multiplexed asynchronous OFDM-FDMA

Peak-to-average power ratio (PAR) reduction algorithms have been thoroughly studied for single system multicarrier signals that tend to have low power efficiency. However, an emerging application for PAR reduction, namely asynchronous multi-plexed signals, has not been examined. This paper frames the problem arising in modern base stations where multiple frequency-division OFDM waveforms are multiplexed so that the combined signal is transmitted through a single PA. PAR reduction on each constituent signal is not sufficient to reduce the multiplexed signal dynamic range. Thus, we propose a symbol-wise phase optimization procedure, multi-channel partial transmit sequences (MCPTS), to reduce the multiplexed signal dynamic range.