Abstract: Considering Amplify-and-Forward cellular relay-enhanced networks with the help of one or more relay nodes,a multi-antenna routing selection algorithm is proposed based on optimal power allocation for the two-hop half-duplex relay channels,After implementing optimal power allocation given a fixed total power condition between the source and the relays,we propose a selection scheme where only one multi-antenna relay with the max received SNR is chosen to assist in transmission.When the base station uses all power resources for its transmission and none is for the relay,only direct link is chosen in transmission.It is shown that the selection-AF scheme maintains full diversity order,and at reasonable power levels has significantly better outage behavior and average throughput than the conventional all-participate scheme.Simulation results demonstrate that the proposed scheme greatly improves system performance with a low algorithm’s complexity,and for actual situation with distance attenuation factor,the performance advantage is also in existence.