A Novel Distributed Space-Time Trellis Code for Asynchronous Cooperative Communications under Frequency-Selective Channels

In most cooperative communications works, perfect synchronization among relay nodes is assumed in order to achieve cooperative diversity. However, this assumption is not realistic due to the distributed nature of each relay node. In this paper, we propose a family of distributed space-time trellis code (DSTTC) that does not require the synchronization assumption. It is shown that the proposed DSTTC can achieve full cooperative and full multipath diversities for the asynchronous transmission by utilizing a specifically designed generator matrix. We derive sufficient conditions on the DSTTC with the minimum memory order. Finally, various numerical examples are provided to verify the analytical studies. The newly proposed codes exhibit good properties, e.g. high energy efficiency and low synchronization cost, and can be applied to distributed wireless networks.