On downlink power control and capacity with multi-antenna transmission

We study the multi-antenna downlink channel in a CDMA wireless network. We introduce optimum power allocation to the proposed channel where the users can control the power of multiple transmit antennas. The model and the resulting power allocation algorithms are used to analyze macrodiversity in the CDMA downlink with various antenna selection and combination concepts. We show that with multiple downlink antennas the multi-user system can be modeled with rectangular non-negative matrices. Furthermore, we quantify the achievable gains for the proposed joint multi-antenna power control concept with Monte-Carlo simulations.