Beamforming Matrix Quantization with Variable Feedback Rate
  We propose an improved beamforming matrix compression by Givens Rotation with the use of variable feedback rate. The variable feedback rate means that the number of bits used to represent the quantized beamforming matrix is based on the value of the matrix. Compared with the fixed feedback rate scheme, the proposed method has better performance without additional feedback bandwidth. 
Chau Yuen, Sumei Sun, Mel Meau Shin Ho