In this paper, we 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, we also consider a scheme where the relays exploit block quantization and random binning, which we call BQRB relaying. We 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. Moreover, it is seen that BQRB achievable rate performance tends to the rate achievable by a point-to-point single-input multiple-output system.
