Novel Constructions of Improved Square Complex Orthogonal Designs for Eight Transmit Antennas

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Constructions of square, maximum rate complex orthogonal space–time block codes (CO STBCs) are well known, however codes constructed via the known methods include numerous zeros, which impede their practical implementation. By modifying the Williamson and Wallis-Whiteman arrays to apply to complex matrices, we propose two methods of construction of <emphasis emphasistype="boldital">square</emphasis>, order-<emphasis emphasistype="italic"><formula formulatype="inline"><tex Notation="TeX">$4n$</tex> </formula></emphasis> CO STBCs from <emphasis emphasistype="boldital">square</emphasis>, order-<emphasis emphasistype="italic"><formula formulatype="inline"><tex Notation="TeX">$n$</tex> </formula></emphasis> codes which satisfy certain properties. Applying the proposed methods, we construct <emphasis emphasistype="boldital">square</emphasis>, <emphasis emphasistype="boldital">maximum rate</emphasis>, order-8 CO STBCs with no zeros, such that the transmitted symbols are equally dispersed through transmit antennas. Those codes, referred to as the <emphasis emphasistype="boldital">improved square CO STBCs</emphasis>, have the advantages that the power is equally transmitted via each transmit antenna during every symbol time slot and that a lower peak-to-average power ratio (PAPR) is required to achieve the same bit error rates as the conventional CO STBCs with zeros. </para>