Simple nonorthogonal 4x4 space-time block codes with rate one and full diversity

In this paper, we present two 4-by-4 nonorthogonal space-time block codes (STBCs) of rate one and full diversity. Constructed via a very simple circulant vector-to-matrix mapping. they are obtained by using a genetic algorithm (GA)-based search procedure to minimize the union bound of average block error probability. The resulting STBCs are comparable to the improved quasi-orthogonal STBC but outperform other counterparts in terms of error performance while retaining the advantages of encoding simplicity and least envelope variations of transmitted signals.