Subcarrier Phase Hopping MIMO-OFDM Transmission Employing Enhanced Selected Mapping for PAPR Reduction

Abstract

This paper proposes a MIMO-OFDM transmission scheme that combines the subcarrier phase hopping for space division multiplexing (SPH-SDM) with an enhanced selected mapping (ESLM). SPH-SDM randomizes the subcarrier phases within an OFDM symbol and makes subcarrier components of the received signal uncorrelated in order to improve BER performance of a MIMO-OFDM coded system. The phase patterns are adjusted so that they can not only randomize the subcarrier phase hopping but also reduce the peak-to-average power ratio (PAPR). In contrast to conventional PAPR reduction techniques for OFDM such as the selected mapping (SEM), ESLM employs roughly quantized IFFT processing for selecting the phase pattern in order to reduce the numerical complexity, and modulates the pilot subcarriers so as to inform the receiver of the selected phase pattern. Computer simulation shows that SPH-SDM with ESLM can increase the frequency diversity gain by channel coding, while simultaneously reducing PAPR by a suboptimum phase pattern