Design of new minimum decoding complexity quasi-orthogonal Space-Time Block Code for four transmit antennas

A new Space-Time Block Code (STBC) achieving full rate and full diversity for general QAM and four transmit antennas is proposed. This code also possesses a quasi-orthogonal (QO) property like the conventional Minimum Decoding Complexity QO-STBC (MDC-QO-STBC), leading to joint ML detection of only two real symbols. The proposed code is shown to exhibit the identical error performance with the existing MDC-QO-STBC. However, the proposed code has an advantage in the transceiver implementation since this code can be modified so that the increase of PAPR occurs at only two transmit antennas, but the MDC-QO-STBC at all of transmit antennas.