A Scalable Approach for Feedback in MIMO Spatial Multiplexing with Linear Receivers

This paper proposes a novel scalable approach to reduce the feedback for downlink multiuser diversity in multiple input multiple output (MIMO) systems. We propose a feedback protocol that features a contention channel consisting of a fixed number of feedback minislot to convey channel state information. Feedback control parameters such as channel quality threshold and feedback probability are jointly adjusted to maximize the throughput performance. Another important feature of the proposed scheme is that MIMO is utilized to support the capture of multiple feedback packets sent simultaneously by different users. This enhances the spectral efficiency for feedback channels, thus may further reduce the feedback resource requirement. We formulate and solve an optimization problem to obtain a good selection of these parameters. Simulations show that the proposed scheme achieves multiuser diversity gain despite a substantial reduction in the feedback requirements.