Distributed space-time block coding for cooperative networks with multiple-antenna nodes

In this paper, we present an extension to our previous work on distributed space-time block coding where we considered cooperative networks with a large set of single-antenna decode-and-forward relays N. Here, we consider the general case where each relay node is equipped with N_T antennas and the destination node has N_R antennas. It is assumed that at any given time only a small, a priori unknown subset of nodes S C N is active. In the proposed scheme, the signal transmitted by an active node is the product of an information-carrying space-time block code (STBC) matrix, which is identical for all nodes, and a unique node signature matrix. It is shown that existing STBCs designed for N_c ≥ 2 co-located antennas are a favorable choice for the code matrix guaranteeing a diversity order of d = min {N_cN_R, N_TN_SN_R} if ns nodes are active. Simulation results show that a considerable gain can be achieved by using multiple-antenna nodes even if the antennas are highly correlated.