A distributed quasi-orthogonal space time block code for cooperative communication with information exchange errors for decode-and-forward relay networks

In this paper, we design the full-rate full-diversity quasi-orthogonal space time block code (QOSTBC) matrix for decode-and-forward (DAF) relay networks with four independent single-antenna source nodes, a single-antenna destination node and a single receive four-trans mit-antenna relay node. In this scheme, we consider the channel states between the four users to select the elements of the DQOSTBC matrix to be decode and forward (DAF) or amplify and forward (AAF) types. Thus the proposed scheme is a DQOSTBC matrix with embedded adaptive DAF/AAF elements, based on the source-to-source channel coefficient is above or below a threshold. By the simulation results, the proposed DQOSTBC with adaptive DAF/AAF matrix elements is approximately 7dB better than the traditional DQOSTBC (all matrix elements are fixed to DAF type, by Li et. al.) at 10^-4 bit error rate (BER) because the traditional DQOSTBC loses full diversity due to information exchange errors.