Mixed joint source-channel coding schemes for multiple-access-relay channels

We study the transmission of correlated sources over multiple-access-relay channels, in which both the relay and the destination have access to side information arbitrarily correlated with the sources. We propose two new joint source-channel coding schemes based on novel combinations of the correlation preserving mapping (CPM) technique with Slepian-Wolf (SW) source coding. The proposed coding schemes are based on the decode-and-forward strategy in which CPM is used for encoding information simultaneously to the relay and to the destination, whereas the cooperation information from the relay is transmitted using SW coding. The two schemes differ in the decoding method used at the destination: While the first scheme uses successive backward decoding, the second uses simultaneous backward decoding. We show that none of the schemes can be proved to be universally superior, but both schemes achieve the best known results in all the special cases previously considered.