Digital signal processing techniques for peak-to-average power ratio mitigation in MIMO–OFDM systems

The focus of this thesis is to mitigate the very large peak-to-average transmit power ratios (PAPRs) inherent to conventional orthogonal frequency division multiplexing (OFDM) systems, particularly in the context of transmission over multi-input multi-output (MIMO) wireless broadband channels. This problem is important as a large PAPR generally needs an expensive radio frequency (RF) power amplifier at the transmitter due to the requirement for linear operation over a wide amplitude range and such a cost would be compounded when multiple transmit antennas are used. Advanced signal processing techniques which can reduce PAPR whilst retain the integrity of digital transmission therefore have considerable potential for application in emergent MIMO–OFDM wireless systems and form the technical contributions of this study. [Continues.

Peak-to-average power ratio mitigation in quasi-orthogonal space time block coded MIMO-OFDM systems using selective mapping.

A study of a peak-to-average power ratio (PAPR) reduction scheme for quasi-orthogonal spacetime block coded multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems based on selective mapping (SLM) is presented. The reduction technique is based upon combining the PAPRs of the transmission blocks from four antennas and exploits the associated antenna diversity gain to mitigate errors in the transmission of the side information (SI) necessary for SLM. Simulation studies are presented which show the cumulative complementary distribution functions (CCDFs) with and without the combining scheme and bit error rates of the overall system. Comparisons are made with single antenna and conventional OFDM schemes