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Abstract : |
Abstract---We derive the capacity and optimal power allocation scheme for a two-user fading broadcast channel where minimum rates must be maintained for each user in all fading states, assuming that the transmitter and both receivers have perfect channel state information. We show that superposition coding can achieve the capacity of such channels and explicitly characterize the boundary of the capacity region. The optimal power allocation scheme for any point on the boundary is a two-level water-filling, where the water-filling is based on effective noise that incorporates the minimum rate constraints. Numerical results are provided for different fading broadcast channels. I., |
