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 log2N bit/s/Hz and its SNR gain does not exceed N , for any ch...

Protocols applicable to bidirectional data transfer via satellite between two earth terminals are analyzed with respect to their achievable rate regions, an information-theoretic comparison. Protocols include amplify-forward, requiring no special satellite processing, and several variations of decode-forward, which necessitate satellite demodulation, decoding, and re-encoding. All such protocol...