Woldegebreal, Dereje H., and Holger Karl. “Multiple-Access Relay Channel with Network Coding and Non-Ideal Source-Relay Channels.”https://doi.org/10.1109/iswcs.2007.4392437__In 2007 4th International Symposium on Wireless Communication Systems. IEEE, 2007.https://doi.org/10.1109/iswcs.2007.4392437 .