A Random Beamforming with Threshold Feedback Scheme for Multi-Antenna System

Sum feedback rate can be a bottleneck for codebook-based multiple-input-multiple-output (MIMO) beamforming. So we propose a scheme using pseudorandom beamforming vectors and a threshold for feedback to address this problem. In our scheme, the basestation produces beamforming vectors in a pseudo-random way, and user calculates the angle between the beamforming vectors and its channel state information (CSI) vector, if the result meets some angle-threshold, the user feeds back its channel quality indicators (CQI). Assuming the base-station serves certain amount of users, adopting this scheme can largely reduce feedback bits with little channel capacity loss. And when the sum feedback rate of uplink channel is upper bounded by a constant, this scheme can have a better performance.