MIMO Precoding and Relay Selection for the Decode-and-Forward Relay Networks

We consider the joint relay and pre-coder selection in the decode-and-forward (DaF) relay network, where multiple relays are employed with multiple antennas. Depending on the channel information, the destination informs the relay and pre-coder selection information to the source and relays with finite bits of information. The source and the selected relay use their own pre-coders to transmit the signal using orthogonal channels. We present a selection criterion based on an upper bound of the pair-wise symbol error probability and provide the conditions for the code-books to achieve the full diversity. For a single antenna destination, we show that the proposed criterion guarantees the diversity order of M_s + KM_r, where M_s,M_r are the numbers of antennas at the source and the relay respectively and K is the number of relays in the network.