Selective Relaying in OFDM Multihop Cooperative Networks

There has been growing interest in the integration of multihop (or relaying) capability into conventional wireless networks. In this paper, we propose an OFDM-based selective relaying scheme, where the relay selection at each hop is performed on a per-subcarrier basis and joint selection is adopted at the last two hops. The outage analysis clearly shows that full spatial diversity gain can be achieved with this proposed selective OFDMA relaying. In contrast, no diversity gain can be obtained if the entire OFDM block chooses the same relay with the highest combined SNR. It is also demonstrated that with coding among the subcarriers, superior performance can be achieved by selective OFDMA relaying with only symbol detection at each relay. This is highly attractive as the processing complexity and decoding delay incurred are very small.