On Improving 4 × 4 Space-Time Codes

In this work, we discuss the construction of 4 times 4 space-time codes for coherent MIMO channels. Recently, the so-called perfect space-time codes have been introduced. These are algebraic codes, which satisfy a plethora of properties, that makes them particularly efficient. They are available for 2,3,4 and 6 antennas, and the optimal perfect code for 2 antennas is known. In an attempt to find the optimal perfect code for 4 antennas, we found and present here a (non perfect) code construction that exhibits better performance than 4 times 4 known codes.