Joint User Selection, Power Allocation, and Precoding Design With Imperfect CSIT for Multi-Cell MU-MIMO Downlink Systems

• Published in: IEEE transactions on wireless communications 2020-01, Vol.19 (1), p.162-176
• Main Authors: Choi, Jiwook, Lee, Namyoon, Hong, Song-Nam, Caire, Giuseppe
• Format: Article
• Language: English
• Subjects: Algorithms; Antennas; Computer simulation; Downlink; Energy conversion efficiency; Interference; Iterative methods; Maximization; MIMO (control systems); Multi-user multiple-input multiple-output (MU-MIMO); Optimization; Power management; Precoding; Quotients; Resource management; Signal to noise ratio; user-selection
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2019.2942916

In this paper, a new optimization framework is presented for the joint design of user selection, power allocation, and precoding in multi-cell multi-user multiple-input multiple-output (MU-MIMO) systems when imperfect channel state information at transmitter (CSIT) is available. By representing the joint optimization variables in a higher-dimensional space, the weighted sum-spectral efficiency maximization is formulated as the maximization of the product of Rayleigh quotients. Although this is still a non-convex problem, a computationally efficient algorithm, referred to as generalized power iteration precoding (GPIP), is proposed. The algorithm converges to a stationary point (local maximum) of the objective function and therefore it guarantees the first-order optimality of the solution. By adjusting the weights in the weighted sum-spectral efficiency, the GPIP yields a joint solution for user selection, power allocation, and downlink precoding. The GPIP can be extended to the multi-cell scenario where cooperative base stations perform joint user-cell selection and design their precodes by taking into account the inter-cell interference by sharing global imperfect CSIT. System-level simulations show the gains of the proposed approach with respect to conventional user selection and linear downlink precoding.