What is a spatial stream?

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What is a spatial stream?

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Spatial streams are used in wireless networks with MIMO multi-antenna technology. Spatial streams are spatially separated, independent data streams. WLAN standards such as 802.11n or 802.11ac support different number of spatial streams. Each spatial flow increases the data flow. Independent data streams can also be used to improve the signal-to-noise ratio or to enable simultaneous data transmission to multiple clients.

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Spatial Stream is a transmission technology found in wireless networks. A spatial stream is a spatially separated, independent stream of data. In networks with MIMO multiple antenna technology (Multiple Input Multiple Output), different numbers of data streams can be implemented depending on the standard used and the number of antennas. WLAN standards such as 802.11n or 802.11ac support up to four or eight spatial streams. The maximum number of data streams depends on the number of transmitting and receiving antennas available.

The data streams use different spatial paths and can transfer data to one or more clients at the same time. If a client supports multiple independent data flows, this increases the maximum possible data flow. The data flow increases linearly with the number of independent data flows. For example, if a single stream achieves a data rate of 72 Mbit / s, up to 288 Mbit / s can be achieved with four spatial streams. Spatial currents are also used to improve the signal-to-noise ratio for wireless data transmission.

Basic information about MIMO

The spatial current is based on MIMO technology. MIMO stands for Multiple Input Multiple Output and describes a transmission technology for wireless networks that, unlike SISO systems (single input single output), uses several transmitting and receiving antennas.

Thanks to special multiplexing and coding processes, not only the temporal but also the spatial dimension can be used to transmit information. Basically, MIMO increases the performance (data rate) and quality of wireless communication connections through this spatial diversity. Transmitting and receiving units with MIMO technology are equipped with several antennas at a certain minimum distance.

A further development of MIMO is multi-user MIMO (MU-MIMO). With MU-MIMO it is possible to send different data streams to several clients at the same time. MIMO technology has established itself and is used in mobile networks and WLAN. WLAN standards such as 802.11n or 802.11ac support MIMO.

Functionality and requirements

A prerequisite for spatial streaming and parallel transmission of independent data streams in a radio channel is the use of several antennas with a certain minimum distance. In principle, one antenna is required for each current. Simplified, a spatial flow works as follows:

The data to be transmitted is multiplexed to different spatially separated data streams in the same spectral channel and transmitted via different antennas. On the receiving side, each antenna receives a single signal from the transmitting antennas. The distance between the transmitting antennas results in phase shifts. By including several transmitting antennas, the individual data streams can be calculated from the received sum signals.

Benefits of Spatial Streams

The use of multi-antenna technology and data transmission via spatially different streams provides the following benefits:

  • the data rate increases linearly with the number of spatial flows
  • the signal-to-noise ratio can be improved
  • independent data streams can be transmitted to multiple terminals at the same time (MU-MIMO)

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