This document discusses two new technologies in 802.11ac Wave 2 wireless networks: MU-MIMO and 160 MHz channels. It notes that 160 MHz channels use a large portion of the 5 GHz spectrum, leaving only a few non-overlapping channels available. MU-MIMO allows an access point to simultaneously transmit to multiple clients, but requires correct traffic patterns and RF conditions to provide benefits. Neither technology is a panacea and poor network design can limit their effectiveness.

1. MULTI-USER MULTIPLE INPUT/OUTPUT (MU-MIMO)
Wave 2 of 11ac offers two mechanisms
not found in Wave 1 equipment:
MU-MIMO and 160 MHz channels.
These are of debatable value for an enterprise network.
160 MHz channels eat up a large portion of the
5 GHz spectrum, in fact, in most regulatory domains
only 2 to 3 non-overlapping channels would be available.
In today’s dense environment it’s far better to use smaller
channel widths with more APs to handle capacity than try
to plan with a small number of wide channels.
MU-MIMO allows an AP to send traffic in parallel to
multiple clients. This can gain more efficient use of the
spectrum (rather than sending packets serially), but traffic
patterns to the clients plus the nature of the RF channel
needs to align correctly for the AP to be able to leverage
this technology. MU-MIMO will not be a panacea for a
poor design or for oversubscribed APs.
1 RF Stream ➟
1 RF Stream➟
1 RF Stream ➟
1 RF Stream➟
Wi-Fi Client
Each 1 x 1:1
Wi-Fi Access Point
2 x 2:2
Spatial
Separation
Required
MU-MIMO
5G160 MHz
Band UNII-1 UNII-2 UNII-3
Channel # 36 40 44 48 52 56 60 64 100 104 108 112 116 120 124 128 132 136 140 144 149 153 157 161 165
20 MHz
40 MHz
80 MHz
160 MHz
DFS DFS
5 GHz Band
5170
MHz
5250
MHz
5330
MHz
5490
MHz
5730
MHz
5735
MHz
5835
MHz
802.11ac wave 2
www.netscout.com/wifi-troubleshooting
802.11ac CHANNEL PLAN