Distributed space-time block coding based cooperative generalized spatial modulation

In this study, two novel distributed space-time block coding based cooperative generalized spatial modulation networks are proposed, and their theoretical analyses are derived. The first network is a three-node cooperative system, consisting of a source (S), a relay (R), and a destination (D). In this design, S sends a GSM symbol to R and D in the broadcast phase. In the relay phase, if R decodes the received signal correctly, it encodes the orthogonal counterpart of the GSM symbol, and sends it to D. If R has a decoding error, it sends a failure to S, and S realizes the R's transmission. The second network is designed with two relays. Here, S sends the GSM symbol to R1$$ {\mathrm{R}}_1 $$, R2$$ {\mathrm{R}}_2 $$, and D in the broadcast phase. In the relay phase, if both relays decode the incoming signal correctly, R1$$ {\mathrm{R}}_1 $$ regenerates the GSM symbol coming from S, and R2$$ {\mathrm{R}}_2 $$ encodes the orthogonal version of it. After encoding, both send them to D in a successive manner. If any or both relays fail, S sends the symbol of R2$$ {\mathrm{R}}_2 $$ in the relay phase. Theoretical and asymptotic analyses as well as simulation results are provided for both networks. It is seen that derived analytical expressions match with the simulation curves. Moreover, since we use the GSM in the proposed methods, their data rates are higher for the same number of transmit antennas. Even for the same spectral efficiency, they provide a significant diversity gain and a better error performance than the existing methods.