Diversity gain of lattice constellation-based joint orthogonal space-time block coding

It is generally thought that space-time block codes (STBCs) can obtain no more than full space diversity. In this study, the authors propose a new construction method of joint orthogonal STBCs based on M-dimensional lattice constellations for obtaining space and time diversities simultaneously. By deriving the Chernoff bound of error probability, they prove the exact diversity gain of the proposed code is M times of that in traditional STBCs. This is a valuable scheme as diversity gain is usually the primary factor to determine the ability of anti-fading. Moreover, the maximum-likelihood decoder for the proposed code just requires joint decoding of M real symbols, whose complexity is acceptable as M, usually, needs not to be too big. Numerical results show that the proposed code has remarkable improvement of performance compared with some typical STBCs under the comparable low decoding complexity.