Distributed decode-forward for broadcast

A new coding scheme for broadcasting multiple messages over a general relay network is presented. The proposed distributed decode-forward scheme combines Marton coding for single-hop broadcast channels and partial decode-forward for relay channels by Cover and El Gamal. For the N-node Gaussian broadcast relay network, the scheme achieves within 0.5N bits from the capacity region, extending and refining a recent result by Kannan, Raja, and Viswanath. The main idea of the scheme is to precode all the codewords initially at the source and to decode and forward parts of them on the fly at the relays.