A Pragmatic Approach Space-Time Code Design

In multiple-input multiple-output (MIMO) systems, the signals transmitted from different antennas are described by a space-time code (STC) matrix, whose properties determine the system performance. Basically, STC design attempts to provide full diversity and high coding gain, and some design techniques also include a complexity criterion to limit the maximum-likelihood (ML) decoder complexity. A closer look at the code matrix reveals that, in all STCs, the matrix elements are a linear combination of the symbol block to be transmitted and can be regarded as new symbols taking their values from a higher signal constellation. However, the signal points in the new constellation are not regularly spaced as in traditional signal constellations.