Joint Feedback and Scheduling Scheme for Service-Differentiated Multiuser MIMO Systems

This paper considers the problem of scheduling, in closed-loop multiuser MIMO systems, a large set of users with different Quality of Service (QoS) requirements, supplied by a single base station (BS) by means of Zero-Forcing Beamforming (ZFBF). We provide a power-and-bandwidth efficient feedback scheme in which only ZFBF-optimal users feedback their CSI, thereby reducing the number of required feedbacks and the computational burden of exhaustive search for best users at the BS. Afterwards, we show that conventional sum-capacity maximizing scheduling policies fall short to meet the requisites of delay-sensitive applications, and we provide appropriate scheduling scheme for such-constrained users. Simulation results demonstrate that the proposed scheduling approach successfully meets both average and instantaneous delay constraints of delay-sensitive applications.