Use MU-MIMO at Your Own Risk - Why We Don’t Get Gb/s Wi-Fi

Abstract

With the ever growing popularity of mobile devices, the demand for wireless bandwidth has also increased, with the mobile users now expecting wireless network quality similar to what they experience with wired networks. Wireless LANs have evolved over the last twenty years, with major breakthrough technologies such as OFDM (Orthogonal Frequency Division Multiplexing), MIMO (Multiple Input Multiple Output), and MU (Multi-User)-MIMO. The latest IEEE 802.11ac standard supports up to 6.9 Gb/s theoretical capacity, but it could only be achieved with 8-streams in a “perfect” environment. Commercial 802.11ac wave 2 APs that include MU-MIMO capability, have only recently been made available in the market. We deployed a few APs from different vendors (that uses chipsets from different vendors) in various office environments and measured user throughput on smartphone mobile devices. We observe an enormous gap between theory and practice, with MU-MIMO often providing less throughput than SU (Single User)-MIMO in various network environments. We analyze the root cause of performance issues and suggest future research directions to achieve Gb/s Wi-Fi in practical deployments.