National Sun Yat-Sen University
In this paper, the authors investigate distributed beam-forming with limited feedback for time varying cooperative network with multiple Amplify-and-Forward (AF) relays. With perfect channel state information, transmit beam-forming has been shown to achieve significant diversity and coding gain in both MIMO and cooperative systems. However, it requires large amount of overhead for receiver to feed back channel information or beam-forming coefficients, which makes it impractical. To perform transmit beam-forming with limited feedback, the destination can choose the best codeword as beam-forming vector from a predetermined codebook.