Robust Precoding Design for Massive MISO Downlink

A low-complexity version of the offset maximization technique for robust precoding is developed for massive MISO downlink systems. Offset maximization precoding provides substantial robustness under different channel uncertainty models, and can be modified to handle per-antenna power constraints. We also provide an improved power loading technique for any set of beamforming directions. This technique provides a low-complexity method for controlling the power required to achieve a specified outage probability at a given target SINR, and it results in significant power savings. The technique also identifies users that should be rescheduled if the system is unable to provide acceptable performance.