Superposition of binary and Gaussian codebooks to relay data in diamond networks

A new communication scheme for Gaussian diamond relay networks based on superposition coding and partial decoding at the relays is presented. A first level codebook is constructed with symbols chosen from a binary alphabet while a second level codebook is composed of codewords chosen with Gaussian symbols. The relays partially decode the message to identify when to amplify the incoming signals. The new communication scheme is a generalization of decode-and-forward, amplify-and-forward, and bursty-amplify-and-forward. The achievable rates are studied in the asymptotic low SNR regime. It is shown that the new scheme outperforms all previously known schemes for some channels and parameter ranges.