Differential distributed space-time block coding

In this paper, differential distributed space-time block codes (DSIBCs) are introduced. These differential DSTBCs are designed for wireless networks which have a large set of nodes N but at any given time only a small, a priori unknown subset of nodes S /spl sub/ N can be active. Channel state information is not required at the cooperating nodes nor at the receiver. The signal transmitted by an active node is the product of an information-carrying code matrix and a unique node signature vector. It is shown that existing differential STBCs designed for N/sub c/ /spl ges/ 2 co-located antennas are favorable choices for the code matrix guaranteeing a diversity order of d = min{N/sub s/,N/sub c/} if ns nodes are active. Efficient methods for the optimization of the set of signature vectors are provided. Possible applications of the proposed DSTBCs include ad hoc and sensor networks employing decode-and-forward relaying.