Covariance based linear precoding in amplify-and-forward cooperative networks

We deal with linear precoding in two-hop multiple-input single-output (MISO) amplify-and-forword (AF) cooperative networks. It is assumed that only limited feedback about channel state information (CSI) is available at the source node where precoding is performed. To reduce the feedback overhead, the precoder is designed based on covariance CSI of the direct channel and relay channel with the constraint of total transmit power at source and relay nodes. The signal model for the described system is derived and the uncoded bit error rate (BER) of cooperative communication is investigated. With the numerical results obtained we can conclude that the precoders designed based on the partial CSI can still help to achieve diversity gain, which could be a reference for systems where full CSI is not so easy to obtain at the source node.