High-rate space-time block codes with fast maximum-likelihood decoding

Orthogonal space-time block codes (OSTBCs) represent an attractive choice of space-time coding scheme because of their simple maximum-likelihood (ML) decoding and full diversity property. However, the code orthogonality property limits their achievable transmission rate. In this paper, new high-rate block codes are proposed that are referred to as orthogonal structure based STBCs. To obtain these codes, the proposed design adds extra-symbols to the OSTBC matrix using different reasonable strategies. Because of the internal OSTBC structure of the proposed designs, the ML decoder can be implemented in a fast way. Simulations validate an improved performance-to-complexity tradeoff of the proposed codes as compared to several other popular choices of space-time codes.