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spatial stream (SS)

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.

Splitting of Spatial Streams in Multi-User MIMO

Splitting of Spatial Streams in Multi-User MIMO

Spatial Stream can be used not only to increase data throughput and signal-to-noise ratio, but also for simultaneous data transmission to multiple clients, as in Multi-User MIMO (MU-MIMO). Multi-stream operation is much more computationally expensive than single-stream operation because multiple spatial streams must be combined in one transmission. The number of spatial streams cannot be greater than the number of antennas in the antenna array. If the number of antennas exceeds the number of spatial streams, the remaining spatial stream can be used to improve the signal-to-noise ratio.

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Englisch: spatial stream - SS
Updated at: 21.07.2017
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