Pragmatic Space-Time Codes for Cooperative Relaying in Block Fading Channels

In this paper we address the construction of Space-Time Codes (STC) for cooperative communications over Block Fading Channel (BFC). More precisely, we consider a pragmatic approach based on the concatenation of convolutional codes and BPSK/QPSK modulation to obtain cooperative codes for relay networks, and derive the pairwise error probability, an asymptotic bound for frame error probability and a design criterion to optimize both diversity and coding gain. Based on this framework we set up a code search procedure to obtain a set of good Pragmatic-STC (P-STC) with overlay construction, suitable for cooperative communication with a variable number of relays in quasi static channel, which outperform in terms of coding gain other STC proposed in the literature We also find that, despite the fact that the implementation of P-STC requires common convolutional encoders and Viterbi decoders with suitable generators and rates, thus having low complexity, they perform quite well in BFC, including quasi-static channel, even with a low number of states and relays.