the option of receiving or transmitting [@IKH2 Sec. III. C]. Therefore, the $\max-\max$ relay selection considered provides the optimal performance that can be achieved by such a scheme, thus yielding the lowest outage bound.

$\maxlink$ relay selection
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The previous relay selection schemes are associated with a two-slot cooperative protocol where the schedule for the source and relay transmission is fixed a priori. Here, this limitation is relaxed and each slot is allowed to be allocated dynamically to the source or a relay transmission, according to the instantaneous quality of the links and the status of the relays’ buffers. More specifically, the proposed $\maxlink$ relay selection scheme exploits fully the flexibility offered by the buffers at the relay nodes and at each time selects the strongest link for transmission (source or relay transmission) among the available links. A source-relay link is considered to be available when the corresponding relay node is not full and therefore can receive data from the source, while a relay-destination link is considered to be available when the relay node is not empty and thus can transmit source’s data towards the destination. The proposed scheme compares the quality of the available links and adjust the relay 