Computer & Electronics Engineering, Department of


Date of this Version



Published in 3rd International Conference on Signal Processing and Communication Systems, Omaha, Nebraska, 28-30 September 2009


Quaternion orthogonal designs (QODs) have been previously introduced as a basis for orthogonal space-time polarization block codes (OSTPBCs). This note will serve to correct statements concerning the optimality of a decoupled maximum-likelihood (ML) decoding algorithm. It will be shown that when compared to coupled decoding, the decoupled decoding is only optimal in certain cases. This raises several open problems concerning the decoding of OSTPBCs.