Adaptive modulation and coding for dual-hop transmission systems with regenerative relaying

We consider the problem of performing adaptive modulation and coding (AMC) in dual-hop transmission systems with regenerative relaying. In particular, we consider a scenario where the AMC on both hops is done independently of each other, thus requiring a potential buffering of data packets at the relay station before they can be forwarded to the actual destination. In this regard, we propose that both the current channel conditions as well as the current buffer filling level are taken into account in the AMC mode selection, so that buffer overflows at the relay station can be completely avoided. We thoroughly analyze our scheme by means of a finite-state Markov model, based on which we derive various different performance measures, such as the average transmission efficiency or the average transmission delay.