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The nodes of wireless communication networks are usually equipped with buffers for temporary data storage as required by many network and transportation layer protocols. For example, in the store-carry-forward protocol employed in delay-/disruption-tolerant networking (DTN), temporally disconnected, intermediate nodes may store data packets until they regain connection to the destination or the next forwarding node [1]. Similarly, in user-provided networks, data packets may be temporarily stored as a means for service differentiation between home users and guest users [2]. However, so far, the potential benefits of exploiting buffers for the physical layer and link layer design have received little attention in the literature. In this article, we present the benefits of buffers for the design of relaying protocols in cooperative communication systems [3]. The basic idea of cooperative communication is that the transmitting nodes help each other to facilitate one another’s communication by willingly acting as relays and sharing their resources. In particular, when a source (e.g., a mobile phone) transmits a packet to the destination (e.g., a base station), nearby relay nodes (e.g., other mobile phones) can overhear this packet, process it, and retransmit it to the destination, thus helping in the transmission process. Cooperative (or relayed) communication can improve the capacity and/or extend the coverage of wireless communications systems. Due to their benefits, simple relay schemes have been/are being included in recent/future wireless standards such as the Worldwide Interoperability for Microwave Access (WiMAX) and Long Term Evolution (LTE) Advanced standards [4]. In cooperative communications, two main relaying protocols are used: full-duplex (FD) relaying and half-duplex (HD) relaying. In FD relaying, the relays transmit and receive at the same time and in the same frequency band. However, given the current radio implementation limitations, FD relaying is difficult to realize in practice because of strong self-interference. As a result, the vast majority of the existing literature on cooperative communications considers HD relaying due to its implementation simplicity. In HD relaying, transmission is usually organized in two successive time slots. In the first time slot, the relay receives data transmitted by a source, and in the second time slot the relay forwards the received data to a destination. We refer to such schemes as conventional relaying in the following. In conventional relaying protocols, the relays employ a prefixed schedule of transmission and reception independent of the quality of the transmitting and receiving channels. This prefixed scheduling may lead to significant performance degradation in wireless systems, where the qualities of the transmitting and receiving channels significantly vary with time, since it may prevent the relays from exploiting the best transmitting and the best receiving channels. Figure 1a illustrates this limitation of conventional HD relaying. In particular, in Fig. 1a, we assume that the relay receives in odd time slots 2i – 1 and transmits in even time slots 2i. For the channel realizations assumed in Fig. 1a, because of the fixed schedule of transmission and reception for the relay, the system cannot exploit the link with the largest signal-to-noise ratio (SNR). More ABSTRACT