Rectangular co-ordinate interleaved orthogonal designs

Abstract

Space-time Block Codes (STBC) from Orthogonal Designs (OD), Quasi-orthogonal Designs (QOD) and Co-ordinate Interleaved Orthogonal Designs (CIOD) have been attracting wider attention due to their amenability for fast (single-symbol decoding for OD, CIOD and double-symbol decoding for QOD) ML decoding and rate-one with full-rank over quasi-static fading channels. The importance of CIOD is due to the fact that, rate-one, full-rank, square ODs for arbitrary complex constellations exist only for 2 transmit antennas while such a CIOD exists for 2,3 and 4 transmit antennas with a slight restriction on the complex constellations (Zafar Ali Khan and B. Sundar Rajan, Proc. IEEE ISIT 2002, p.275, 2002; DRDO-IISc Tech. Report No. TR-PME-2002-17, 2002). These limitations motivate study of rectangular (non-square) designs. One way of obtaining rectangular designs is by deleting columns from square or non-square ODs or CIODs. We present a new construction of rectangular single-symbol decodable designs that have higher maximum mutual information than those obtained by deleting columns of CIODs and has lower Peak-to-average-power Ratio (PAPR). Simulation results are presented for three and five transmit antennas and compared with that of OD, QOD, CIOD to demonstrate the superiority of the proposed rectangular designs.