Amplify-and-forward versus decode-and-forward relaying: which is better?

Abstract

Performance of multi-hop MIMO relay channels under the amplify-and-forward and decode-and-forward proto- cols are compared via the capacity and SNR gains. In an N - hop channel of linear topology with multi-antenna source and destination and single-antenna relay nodes, the capacity gain of the DF relaying over the AF one does not exceed log 2 N bit/s/Hz and its SNR gain does not exceed N , for any channel realization. This conclusion also applies to selection relaying, to the outage probability/capacity and the ergodic capacity in an arbitrary block-fading channel, and can be further extended to hybrid relaying. The conditions under which the DF and AF