Mapping techniques for transmit diversity precoding in SC-FDMA systems with four transmit antennas

Single-Carrier Frequency Division Multiple Access (SC-FDMA) is a recent modulation technique combining most of the advantages of Orthogonal Frequency Division Multiple Access (OFDMA) with the low Peak-to-Average Power Ratio (PAPR) of single-carrier transmission. This paper presents the key design criteria for space-time and space-frequency transmit diversity precoding in SC-FDMA with four transmit antennas. In particular, we propose a novel quasi-orthogonal space-time-frequency precoding. We show that our proposed precoding conserves the single-carrier property of the signal on all of the four transmit antennas with improved performance at the expense of a slight increase of the frame granularity with respect to existing space-frequency solutions.