Design of randomized space-time block codes for amplify-and-forward cooperative relaying

Cooperation diversity schemes employing distributed spacetime block coding (STBC) techniques have been proposed for wireless networks to increase system capacity and coverage even when each node is only equipped with a single antenna. Capitalizing on randomized STBC, a decentralized coding method that has been developed for decode-and-forward relaying, a cooperative communication protocol is proposed for amplify-and-forward relays, which has three distinguishing features that make it fully decentralized: (i) each relay operates in a completely autonomous fashion; (ii) coherent decoding is carried out at the destination without knowing the number of cooperating nodes and the relaying parameters; (iii) maximum likelihood decoding at the destination can be implemented on a symbol-by-symbol basis in the case of full-rate orthogonal STBC. Numerical results are provided to highlight the effectiveness of the proposed scheme in comparison with previously-proposed competitive alternatives.