Adaptive scheduling for unitary precoded multiuser MIMO transmission with limited feedback

In this paper, we propose an adaptive scheduling method for unitary precoded downlink multiuser MIMO transmission based upon limited feedback. To alleviate the conflict between the scheduling gain and the quantization precision, the proposed method allocates a set of weights to each of the matrices within the codebook. These weights are selected adaptively according to the number of active users and the codebook size, and used by all users when quantizing their channel vectors, based on which the base station schedules the multiuser transmission. It is verified by simulations that the proposed method outperforms the conventional method when the codebook size is moderate or large.