Siemens SIMATIC NET System Manual page 211

Multi-User MIMO
With multi-user MIMO, multiple frames are sent simultaneously to different multi-user MIMO
clients over the same frequency range. A multi-user MIMO therefore supplies up to four
multi-user MIMO clients with data simultaneously.
Spatial mutliplexing
With spatial multiplexing, different information is sent using the same frequency. The data
stream is distributed over n transmitting antennas; in other words, each antenna sends only
1/n of the data stream. The division of the data stream is restricted by the number of
antennas. The signal is reconstructed at the receiver end. Due to the spatial multiplexing,
there is a higher signal-to-noise ratio and a higher data throughput.
Accelerated guard interval
The guard interval prevents different transmissions being mixed together. In
telecommunications, this mixing is also known as intersymbol interference (ISI).
When the send time has elapsed, a send pause (guard interval) must be kept to before the
next transmission begins.
The guard interval of IEEE 802.11a /b/g is 800 ns. IEEE 802.11n/ac can use the reduced
guard interval of 400 ns. You specify the guard interval on the WBM page "AP 802.11n/ac
(Page 131)".
Industrial Ethernet
System Manual, 09/2019, C79000-G8976-C242-10
4.6 SCALANCE W components for the Industrial Wireless LAN
SCALANCE network components
211