Perfect Space Time Block Codes
  In this paper, we introduce the notion of perfect space-time block codes (STBC). These codes have full rate, full diversity, non-vanishing constant minimum determinant for increasing spectral efficiency, uniform average transmitted energy per antenna and good shaping. We present algebraic constructions of perfect STBCs for 2, 3, 4 and 6 antennas. 
F. Oggier, G. Rekaya-Ben Othman, J.-C. Belfiore and E. Viterbo