Channel feedback quantization methods for MISO and MIMO systems

We investigate the quantization of multiple antenna channel to feed back through a low-rate feedback channel. Specifically, for multiple-input single-output (MISO) systems, we propose a new design criterion and the corresponding design algorithm for quantization of the random beamforming vector. For multiple-input multiple-output (MIMO) channels, which have multiple orthonormal vectors as channel spatial information for quantization, a matrix factorization method is proposed which provides a way to exploit the geometrical structure of orthonormality while quantizing the spatial information matrix. Results show that the quantization bit allocation over multiple spatial channels has a critical effect on the performance, and that the optimum bit allocation depends on the operating transmit power of the system.