Phuong Cao1, Tobias J. Oechtering1, Mikael Skoglund1
15:40 - 16:00 | Thu 15 Mar | HID | S04-2
This paper designs precoding matrices for massive MIMO systems with a sub-connected architecture, RF power constraints and per-antenna power constraints. The system is configured such that each RF chain serves a group of antennas. It is shown that the optimal precoder is designed based on a generalized water-filling and joint sum and per-antenna optimal power allocation solution while the optimal analog precoder is designed based on the per-antenna power allocation only. We study the most interesting case where the power constraint on the RF chain is smaller than the sum of the corresponding per-antenna power constraints. Therefore, the optimal power is allocated based on two properties: Each RF chain uses full power and if the optimal power allocation of the unconstraint problem violates a per-antenna power constraint then it is optimal to allocate the maximal power for that antenna.