Skip to Main Content
In this paper, we study the asynchronous cooperative diversity schemes employing the amplify-and-forward (AF) protocols over the frequency-selective channel. We consider three time-division-multiple-access (TDMA) based cooperation protocols and derive the corresponding pairwise error probabilities (PEP). From our analysis, it is seen that of the paths from the source to relays and from relays to the destination, those with smaller diversity order result in the bottleneck for the overall system performance. We propose a new type of the distributed space-time trellis code (DSTTC) that can achieve full diversity for the asynchronous transmission by utilizing a specifically designed generator matrix. The optimal DSTTCs with the minimum memory order are found by the exhaustive computer search. Finally, various numerical examples are provided to corroborate the analytical studies.