Improved Differential Unitary Space-Time Signal Design for Two to Six Transmit Antennas

Abstract

This paper addresses optimization of differential unitary space-time modulation (DUSTM) for more than two transmit antennas. We demonstrate that the union bound on the block error probability of DUSTM codes can be considerably simplified for various cases of non-group DUSTM constellations. We also demonstrate that rotation matrices applied to diagonal DUSTM codes can be considered as special cases of Alamouti style block codes. Utilizing these two results, and some simplified design criteria, various DUSTM codes are derived for more than two transmit antennas which give superior performance to previously proposed codes over a wide range of SNR.

Differential unitary space‐time signal designs with improved performance using parametric equivalence

“…The following reparametrisations of rotations (based on first reparametrisation) applied to diagonal unitary matrices apply to Equations (15)(16)(17), with respect to M = 3, 5 and 6 antennas √ a 2 …”

“…The following reparametrisations of rotations (based on first reparametrisation) applied to diagonal unitary matrices apply to Equations (15)(16)(17), with respect to M = 3, 5 and 6 antennas √ The circulant property of the singular values S of the two reparametrisations based on integer parameters is shown below. Recall that this circulant property is dependent on…”

“…The first parametric equivalent constellation described is that the matrix rotations in the rotation method can be represented as constituent matrices of the same type as the 2 × 2 space-time block codes introduced by Alamouti [14,15]. This allows for further optimisation of resulting constellations with a simplified union bound criterion.…”