With MIMO technology, the access point sends several independent data streams. Each data stream is called a spatial stream (SS) because it uses different paths through the room and transports the same or different data to the receiver or WLAN client. Depending on the WLAN concept, a transmitter can support two, four or even eight spatial streams. WLANs based on 802.11n support a maximum of four spatial streams, and 802.11ac
even eight. The number of spatial streams is decisive for
thedata rate. Each Spatial Stream contributes with the basic data rate to increase the resulting data rate. For example, the data rate of 802.11n at a bandwidth of 20 MHz is 72 Mbps
with a single spatial stream, doubling to 144 Mbps with two spatial streams, and further doubling to 288 Mbps with four spatial streams.