MIMO beamforming with quantized feedback in ad hoc networks: Transmission capacity analysis

We investigate the performance of MIMO beamforming with quantized feedback in ad hoc networks. The primary findings are that a moderate number of feedback bits are sufficient to obtain significant transmission capacity gains compared to non-feedback schemes, whilst also achieving a high percentage of the transmission capacity obtained with unlimited feedback. We demonstrate that this achievable percentage is larger in high path loss environments, and that the number of feedback bits to maintain a fixed gain increases with the number of transmit antennas. These findings are obtained by new transmission capacity expressions which we derive.