Multiple-DFT Spread Orthogonal SFBC with Low PAPR

Space-Frequency Block Code(SFBC) has full diversity in MIMO systems, and Single-carrier Frequency Division Multiple Access(SC-FDMA) is a modulation technique with low Peak-to-Average Power Ratio(PAPR) of single-carrier transmission, but transmitting Orthogonal SFBC(OSFBC) signals by SC-FDMA will lead to high PAPR. To solve this problem, a new transmitting scheme based on multi-DFT spectrum spreading with four transmit antennas was proposed. By setting up parallel DFT units, frequency domain symbols were arranged crosswise with equal spacing on subcarriers, avoiding adjusting the symbol order in one DFT units. The corresponding transmitter and receiver were given and were easy to implement. It was proved that the generated signal is equivalent to the sum of multiple single-carrier signals according to frequency cyclic shift and interpolation property, and the overall PAPR obtained a low value close to single-carrier signals. Furthermore, the proposed scheme does not degrade the BER performance, and has the same diversity of OSTBC.