Distributed Double-Differential Orthogonal Space-Time Coding for Cooperative Networks

In this paper, distributed double-differential coding is proposed to avoid the problem of carrier offsets in amplify and forward protocol based cooperative network with two relays. A double-differential orthogonal-space-time block code is transmitted by the relays in a distributed manner without channel knowledge. We derive a low complexity linear decoder which does not require the channel and carrier offset knowledge. A pairwise error probability (PEP) analysis is also conducted and we found an upper bound of the PEP for the proposed system. In addition, an optimized power allocation is proposed to improve the SER performance of the system.