A General Achievable Rate Region for Multiple-Access Relay Channels and   Some Certain Capacity Theorems
  In this paper, we obtain a general achievable rate region and some certain capacity theorems for multiple-access relay channel (MARC), using decode and forward (DAF) strategy at the relay, superposition coding at the transmitters. Our general rate region (i) generalizes the achievability part of Slepian-Wolf multiple-access capacity theorem to the MARC, (ii) extends the Cover-El Gamal best achievable rate for the relay channel with DAF strategy to the MARC, (iii) gives the Kramer-Wijengaarden rate region for the MARC, (iv) meets max-flow min-cut upper bound and leads to the capacity regions of some important classes of the MARC. 
Mohammad Osmani-Bojd, Assadallah Sahebalam, Ghosheh Abed Hodtani
cs.IT math.IT