Adaptive amplification for amplify-and-forward dual-hop cooperative systems

The amplify-and-forward protocol is a simple but effective relaying for cooperative communications systems because its associated relay node does not take encoding/decoding into consideration to re-transmit signals. However, the interference and multipath fades during the previous hop are also amplified. In this paper, based on the zero-forcing (ZF) concept, an adaptive amplification factor is investigated to counteract the effects of the multipath-fading channel. Numerical results show that the ZF-based adaptive amplification according to both channel impulse responses possesses the best system performance in a dual-hop cooperative system.