Impact of direct link on outage of cooperative full-duplex relaying

In theory, full-duplex (FD) relaying can double the spectral efficiency achieved with half-duplex relaying in cooperative communications. However, FD relaying suffers from self-loop interference and cross-talk interference, and the messages from the direct link (the link between the source and the destination) may interfere with the relay-to-destination transmission. In this paper, we analyze the impact of the direct link on the outage of FD relaying from two aspects: 1) the messages from the direct link are viewed as interference, which will lead to severe performance loss; and 2) the messages from the direct link are combined with the relays' transmissions, which can be considered as a lower bound on the outage for FD relaying.