Approximately universal optimality over several dynamic and non-dynamic   cooperative diversity schemes for wireless networks
  In this work we explicitly provide the first ever optimal, with respect to the Zheng-Tse diversity multiplexing gain (D-MG) tradeoff, cooperative diversity schemes for wireless relay networks. The schemes are based on variants of perfect space-time codes and are optimal for any number of users and all statistically symmetric (and in some cases, asymmetric) fading distributions.   We deduce that, with respect to the D-MG tradeoff, channel knowledge at the intermediate relays and infinite delay are unnecessary. We also show that the non-dynamic selection decode and forward strategy, the non-dynamic amplify and forward, the non-dynamic receive and forward, the dynamic amplify and forward and the dynamic receive and forward cooperative diversity strategies allow for exactly the same D-MG optimal performance. 
Petros Elia and P. Vijay Kumar