Amplify-and-forward versus decode-and-forward relaying: which is better?
Georgy Levin, Sergey L. Loyka · Repository for Publications and Research Data (ETH Zurich) · 2012
Abstract—Performance of multi-hop MIMO relay channels under the amplify-and-forward and decode-and-forward protocols 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 relaying have nearly identical performance are identified. I.