Amplify-and-forward relaying to improve capacity and error rate at destination terminal

This paper proposes a variable gain amplify-and-forward (AF) protocol with a gain normalization factor which varies with the backward channel coefficient. To appreciate the contribution of the proposed scheme, called the k-normalized variable gain (kVG), it is compared with some AF ones and decode-and-forward (DF) protocol. Numerical results show that kVG not only reduces the BER of the benchmarked AFs, it achieves a higher average SNR and hence a higher average capacity. Although it is outperformed by DF, it is able to slightly reduce the performance gap between AF and DF relaying, which is our main objective. Furthermore, it can provide even a more attractive and practical solution, since AF relaying generally offers simpler implementation compared to DF.