Novel Unitary Space-Time Signal Design

This paper presents a novel unitary space-time signal design for two to six transmit antennas which is applicable to both coherent and differential space-time coding. In the context of differential modulation, this new space-time signal design demonstrates good bit-error performance when compared with previously designed codes both theoretically and by simulation. The design for two antennas is shown to subsume previous differential unitary space-time signal constellation with the property that the number of optimum codes scales with the size of the constellation. As part of analysis of this novel design an exact expression for the union bound on error probability is given for differential unitary space-time modulation. The calculation of the union bound on bit-error probability can also shown to be considerably simplified for these codes allowing for the simplified design of larger constellations.