Low Complexity User Grouping Vector Perturbation

In this letter, at first, a low complexity block diagonalized vector perturbation (BD-VP) algorithm is proposed for multiuser MIMO downlink, which is based on our proved proposition on the relationship between the right inverse of the stacked channel matrix of all users and the channel matrix of each user. With the proposed algorithm, we show that although flexible in adaptive modulation (AM) for different users, the BD-VP algorithm is suboptimal in minimizing the total transmit power. To achieve the flexibility and performance (diversity gain and achievable sum rate) tradeoff, we further develop a low complexity user grouping vector perturbation (UG-VP) algorithm. Analysis and simulation results validate the proposed algorithms.