Low Complexity Constructions of Multi-Block Space-Time Codes Achieving Diversity-Multiplexing Tradeoff

A construction of low complexity multi-block space- time codes that is optimal with respect to the diversity- multiplexing tradeoff (DMT) when the coding is applied over any number of independent fading blocks is presented in this paper. Specifically, for a MIMO system over a quasi-static Rayleigh block fading channel with quasi-static interval T, the present construction requires a number field that is cyclic Galois over Q(i) of degree only T, while the previously known construction requires a number field of degree mT, where m is the number of coded fading blocks. Thus, the present construction provides a great reduction on both the encoding and decoding complexities of multi-block space-time codes comparing to earlier constructions, and it achieves complexity at the same level as that of the conventional DMT-optimal single block space-time codes.