Hybrid Forwarding Scheme for Cooperative Relaying in OFDM Based Networks

In this paper, we propose a hybrid forwarding scheme for cooperative relaying in orthogonal frequency division multiplexing (OFDM) based networks. The proposed hybrid forwarding scheme changes the type of the forwarding scheme used by a relay terminal on a per sub¿carrier basis. It adaptively decides to use either "Amplify and Forward (AF)" or "Decode and Forward (DF)" or "no relay" according to the instantaneous Signal to Noise Ratio (SNR) conditions between the source, relay and destination terminals. This decision is made based on analytically derived equations, which makes it possible to take into account all the link conditions in a relay network with low computational complexity. The bit error performance is presented for cooperative receive diversity with AF, with DF, with proposed hybrid forwarding scheme and for noncooperative transmission. Our results show that the proposed hybrid forwarding scheme significantly outperforms conventional cooperative relaying with AF and DF, and direct transmission schemes.