Double Space–Time Line Codes

In this paper, an <inline-formula><tex-math notation="LaTeX">$M\times 4$</tex-math></inline-formula> double space-time line code (D-STLC) is designed for a system with <inline-formula><tex-math notation="LaTeX">$M$</tex-math></inline-formula>-transmit and four-receive antennas whose channel state information is available at the transmitter. By delivering two independent STLC data streams simultaneously, both spatial diversity and multiplexing gains are obtained, like a <inline-formula><tex-math notation="LaTeX">$4\times M$</tex-math></inline-formula> double space-time transmit diversity (DSTTD) system that transmits two space-time block coded data streams. It is analytically shown that the decoding signal-to-interference-plus-noise ratios of D-STLC and DSTTD are identical to each other, and furthermore, it is numerically verified that the proposed D-STLC significantly outperforms a conventional <inline-formula><tex-math notation="LaTeX">$M\times 4$</tex-math></inline-formula> STLC scheme and other existing spatial-diversity and spatial-multiplexing schemes, such as precoded space-time block code and precoded spatial multiplexing, in terms of achievable rate and bit-error-rate performance as the signal-to-noise ratio and/or transmission data rate increase.