On Space-Time Block Codes from Coordinate Interleaved Orthogonal Designs

Space-time block codes (STBC) using coordinate interleaved orthogonal designs (CIOD) proposed recently by Khan and Rajan allow single-complex symbol decoding while offering higher data rates than orthogonal STBC. In this paper, we present the equivalent channels of CIOD codes. A new maximum likelihood metric is also derived, which is simpler than the one shown by Khan and Rajan. The exact symbol pair-wise error probability and a tight union bound on symbol error rate are derived. The tight union bound can be used to analyze the performance of CIOD codes with arbitrary constellations. We provide new optimal rotation angles based on minimizing the union bound for various constellations. Furthermore, a new signal design combining signal rotation and power allocation is presented for rectangular quadrature amplitude modulation.