Parallel Relay Networks With Phase Fading

In this paper, the authors consider Gaussian parallel relay networks with phase fading where a source node wants to communicate with a destination node with the assistance of two intermediate relay nodes. For this scenario, outer bounds are derived and three achievable schemes are considered. As well as Amplify-and-Forward (AF) and Decode-and-Forward (DF) schemes, they also consider a scheme where the relays exploit block quantization and random binning, which they call BQRB relaying. They show that in the broadcast channel limited regime, where received powers at the relay nodes are very small, BQRB outperforms the other schemes with increasing multiple access channel quality.