No abstract

Multi-user MIMO (MU-MIMO) is an important technology to improve data transmission efficiency for future network, such as 5G and WiFi 6, due to its ability of enabling multi-users' concurrent transmissions. To achieve concurrent diversity gains, MU-MIMO network resource allocation relies on the feedback of Channel State Information (CSI) from multiple clients. CSI feedbacks from large user population, however, heavily degrade the throughput of a MU-MIMO network. Pursuing smart CSI feedback, we present a CSI timeliness-aware balanced mechanism, named TAB. It is a novel MU-MIMO protocol to eliminate unnecessary feedback overhead and improve CSI utilization within channel coherence time. TAB is fully compatible with the WiFi 5/6 standard and most state-of-the-art CSI feedback strategies, and is easy to be deployed on existing WiFi systems. Our software-radio based implementation and testbed experimentation demonstrate that TAB substantially improves the throughput of both downlink and uplink MU-MIMO network by 1.5× at least.