Multi-User, Multiple Input, Multiple Output (MU-MIMO)
This Wave 2 AC feature improves upon Single User MIMO technology, which allows one client device to communicate wirelessly with an access point across multiple spatial streams at the same time. Before MIMO, client devices could only transmit on one radio spatial stream at a time.
|Image from ontheflywifi.net|
160 MHz Channels
The 802.11ac standard allows devices to utilize significantly larger channel bandwidths. While 802.11n only permitted 20 MHz and 40 MHz channels on the 5 GHz band, with 802.11ac, 80 MHz, and 160 MHz sized-channels are possible. The bigger the channel, the higher the data transfer rate.
The previous version of the Certified stamp for 802.11ac only guaranteed use with 80 MHz channels. The new version promises compatibility for 160 MHz channels.
|Image from meraki.cisco.com|
Four Spatial Streams
The latest "Certified" indicator from the WiFi Alliance means the device can operate on four spatial streams, a boost from the three promised previously. That means a potential 33% boost in transfer speeds over the same devices communicating with only three spatial streams.
When it comes to designing your network infrastructure, it's important to remember that the slowest device in a data chain will act as a bottle neck within that chain, and WiFi is no exception. Having 802.11ac Wave 2 access points throughout your building won't impact a performance boost over Wave 1 APs if your client devices aren't also rated for Wave 2 features. While Wave 2 clients are still few and far between (the technology is still fairly new), this new certification standard for 802.11ac from the WiFi Alliance will make it easier for IT to ensure their wireless devices are all firing on the same cylinders.