  A pragmatic approach for the construction of space-time codes over block
fading channels is investigated. The approach consists in using common
convolutional encoders and Viterbi decoders with suitable generators and rates,
thus greatly simplifying the implementation of space-time codes. For the design
of pragmatic space-time codes a methodology is proposed and applied, based on
the extension of the concept of generalized transfer function for convolutional
codes over block fading channels. Our search algorithm produces the
convolutional encoder generators of pragmatic space-time codes for various
number of states, number of antennas and fading rate. Finally it is shown that,
for the investigated cases, the performance of pragmatic space-time codes is
better than that of previously known space-time codes, confirming that they are
a valuable choice in terms of both implementation complexity and performance.
