Joint source-channel cooperation: diversity versus spectral efficiency

User cooperation is a spatial diversity technique where multiple terminals form a virtual antenna array to combat fading. We incorporate source coding into the cooperation scenario and analyze cooperation protocols with respect to the average distortion they achieve. We first compare the amplify-and-forward (AF) protocol to direct transmission (DT) and show that it does not increase the performance in the average distortion sense. Then we propose two new cooperation protocols which achieve better performance by increasing the spectral efficiency while still providing diversity, yet maintaining the simple nature of the previous protocols