Capacity Region of a MAC with a Wireless-Powered DF Relay-to-Destination Link

We consider a two-user multiple access channel (MAC) with a wireless-powered relay-to-destination (R- D) link, where the relay adopts the decode-and-forward (DF) relaying strategy and operates in half-duplex mode. Each frame is divided into three phases. In the first phase, the relay harvests energy from a radio frequency (RF) signal sent by a dedicated Power Beacon (PB). The relay then receives information from user nodes in the second phase and forwards it to the destination in the third phase using its harvested energy. We are interested in the system performance with the wireless-powered relay, as compared to the conventional MAC with an R-D link. In particular, we investigate the sum-rate and capacity region of the MAC with wireless-powered relay by jointly optimizing the time scheduling and transmit powers at the user nodes. The optimal scheduling and power allocations are obtained for both the sum-rate and the boundary points on the capacity region. Simulation results validate our theoretical analysis and demonstrate the effectiveness of our proposed solution.