A high coding gain and low decoding complexity STBC for four transmit antennas

Space-time block codes (STBCs) have attracted considerable attention as they provide reliable communication in multi-antenna systems. STBCs work on the principle of multiple transmissions of a data stream from different transmit antennas in multiple time slots. This redundancy reduces the data rate of the STBCs. In this paper, we propose a mapping function for PAM and square QAM constellation. Based on this mapping function, we propose an STBC for four transmit antennas which achieves high coding gain. We derive an expression of coding gain of the proposed STBC. It is further shown that the proposed STBC achieves full diversity and has a low peak-to-average power ratio (PAPR). A low-complexity decoder for the proposed STBC is also derived. We show that the proposed STBC outperforms the existing STBCs for four transmit antennas in terms of coding gain, PAPR, and decoding complexity.