Non-codebook based precoding for multi-user MIMO downlink

A method of performing the operations of a wireless communication system comprising:

• using a base station comprising a plurality of precoders, wherein the base station receives a plurality of input signals that are selectively provided to the plurality of precoders, the plurality of precoders preforms precoding operations on the plurality of input signals and outputs a first output signal, the base station comprises at least two separate algorithms, wherein a first algorithm minimizes total transmit power per antenna under signal to interference and noise ratio (SINR) target constraints, and a second algorithm maximizes an SINR under a sum power constraint per data stream;
• wherein each of the at least two separate algorithms is to determine a power allocation and obtain a plurality of efficient precoders;
• wherein the each of the at least two separate algorithms iteratively update downlink power allocation, downlink beamformers, uplink power allocation, a plurality of Lagrange multipliers, and uplink beamformers, and the each of the at least two separate algorithms stops when the downlink power allocation and uplink receive beamformers converge
• wherein the downlink power allocation is calculated by further minimizing a sum power with per-antenna power constraints of the base station with the SINR targets.