Buffer-Aided Relaying in Cooperative Networks

Traditional half-duplex relaying schemes partition the packet transmission slot into two phases, where the SourceRelay link transmission is in the first phase, and the RelayDestination link transmission occurs in the second phase. As a result, the relay that received the source signal is the same as the one that is subsequently forwarding the signal towards the destination. However, these relaying schemes halve the maximum achievable multiplexing gain and result in bandwidth loss. In order to overcome these limitations, several techniques have been proposed in the literature. With the adoption of buffer-aided relays, the coupling between receiving and transmitting relays is broken, since different relays could be selected for transmission and reception, thus allowing increased degrees of freedom. In this contribution, we exploit the potential of buffer-aided relays and adopt a single phase slot in which either the Source-Relay or the Relay-Destination link is activated, or both provided certain conditions hold. This new approach opens a new avenue for research and design of relay selection policies and transmission schemes that facilitate increased throughput and multiplexing gains; we propose several such schemes and discuss both their benefits and limitations.