| Duality between the uplink and the downlink is a powerful concept for system design in wireless communications. The aim of this thesis is to illustrate the duality in a new communication scenario where the transmitter is subject to per-antenna power constraints. There are two main results in this thesis: First, it is shown that the capacity region of a downlink broadcast channel with per-antenna power constraints is exactly the same as that of a dual uplink multiple-access channel with an uncertain noise. Second, it is shown that for a downlink channel with per-antenna power constraints, the best achievable SINR region with transmitter beamforming is exactly the same as that of an uplink channel with receiver beamforming and uncertain noise. These two results not only provide a convex optimization framework for the previously known duality results, they also allow input optimization problems with per-antenna power constraints to be solved. |
