Performance of Adaptive Transmitting Mode Selection for Wireless MIMO Broadcast Channels with Limited Feedback

Multiuser multiple-input multiple-output (MIMO) system with limited feedback are noise-limited at low SNR regime and interference-limited at high SNR regime. Specifically, there is a sum rate ceiling which can not be avoided by increasing the transmit power alone. This paper considers a practical design called per user unitary and rate control (PU2RC), and introduces an adaptive transmitting mode selection scheme for optimizing the overall spectral efficiency of a PU2RC system. According to the channel information from mobiles, base station uses this proposed scheme to select single-user or multiuser mode transmission adaptively. Performance analysis and simulation results show that this scheme achieves high throughput and gets unbounded capacity growth when increasing the number of active users or in high SNR regime.