[17] deals also with a multiple relay systems and relay selection strategy.
Later, in [26] and [27] the idea of buffer-aided relaying was expanded to multiple relay systems, where the authors have proposed the max-max link selection (MMLS) protocol firstly.
Simulation results illustrate that the robust transceiver/relays joint architecture for an AF-MIMO multiple-relay system outperforms the non-robust transceiver/relays design.
An efficient antenna-pair selection scheme is proposed for a non-regenerative dual-hop amplify-and-forward (AF) multiple-input multiple-output (MIMO) multiple-relay system in which multiple antennas are placed at each node over correlated fading channels in the paper.
The system we investigate is a multiple-layer-multiple-relay system, in reality, it is rarely possible that the numbers of available relays in all layers are equal.
As compared to the single-relay systems, a higher spatial diversity gain is announced in a multiple-relay system due to more redundant signal transmission paths being created in it.
In the paper, robust joint optimization of the source/relays precoders and destination equalizer is proposed for non-regenerative dual-hop multiple-input multiple-output (MIMO) amplify-and-forward (AF) multiple-relay systems with correlated channel uncertainties.
For multiple-relay systems, advanced relaying mechanisms such as distributed space-time coding[13], relay selection[14], network coding[15], and collaborative beamforming[16] were investigated to further benefit the cooperative systems.
Relay selection is proven to be one of the most efficient methods to improving the spectral efficiency and maximizing the spatial diversity gain at the same time in multiple-relay systems [13 18].
For high end-to-end channel capacity, the amplify-and-forward scheme multiple-hop multiple-input multiple-output relay system is considered.
Since the channel capacity of direct link is much smaller than that of the multiple-hop relay system in the proposed propagation environment, hereafter, only the channel capacity of the multiple-hop relay system is considered.
