Distributed optimal resource allocation for fading relay broadcast channels

Resource allocation for a fading orthogonal relay broadcast channel model is investigated, where the source broadcasts to two users using a time-division (TD) scheme in one channel, and the two users transmit relay signals to each other in another orthogonal channel. The channel bandwidth resource is assumed to be allocated equally for broadcast and relay transmissions. Separate power constraints are assumed at the source and the two users. The fading state information is assumed to be known at both the transmitter and receiver of each link, and hence the source and the two users can allocate their power adaptively according to the instantaneous channel state information in a distributed manner. For a fixed allocation of time (for TD broadcast) and power, an achievable rate region based on the relays using the decode-forward scheme for this model is derived. The resource (time and power) allocation is then optimized to maximize each boundary point of this rate region.