Capacity Theorem and Optimal Power Allocation for Frequency Division Multiple-Access Relay Channels

The capacity region of general Multiple-Access Relay Channel (MARC) has long been an open question. In this paper, we consider MARC with orthogonal components, where the channel from the source senders to the relay node is orthogonal to the channel from the source senders and relay to the destination. We give the capacity theorem for the discrete memoryless MARC with orthogonal components. Based on the result, we obtain the capacity region of frequency-division Gaussian MARC. The optimal power allocation for the source nodes to allocate power on different frequencies is investigated. Numerical results show that the optimal allocation of power can achieve the maximum sum rate.