Radio resource optimization for the half-duplex relay-assisted multiple access channel

We study the achievable rates of cooperative transmission in the multiple access Gaussian channel when the assisting relays are half-duplex and all terminals are power constrained. We define the problem of assigning the radio resources to the first and second phase of the cooperative transmission in order to get the maximum achievable rate region, for TDMA, FDMA and superposition coding. We show that the problems are convex and evaluate the optimum solution.