Wi-Fi Spatial Streaming Explained

Wi-Fi Spatial streaming or multiplexing (often shortened to SM or SMX) is a transmission technique used in MIMO wireless communication to transmit independent and separately coded data signals, so called streams, from each of the multiple transmit antennas. This results in the space being reused, or multiplexed, more than one time.

On each band, the Wireless-N standard is available in three primary configs, depending on the number of spatial streams being used. The lowest, single stream (1x1), dual stream (2x2) and three-stream (3x3), offering cap speeds of 150Mbps, 300Mbps and 450Mbps.

This in turns creates three types of true dual-band routers: N600 (each of the two bands offers a 300Mbps speed cap), N750 (one band has a 300Mbps speed cap while the other caps at 450Mbps) and N900 (each of the two bands allows up to 450Mbps cap speed).

802.11ac: Sometimes referred to as 5G Wi-Fi, this latest Wi-Fi standard operates only on the 5GHz frequency band and currently offers Wi-Fi speeds of up to 2167Mbps (or even faster with the latest processors) when used with a quad-stream (4x4) setup. The standard also comes with 3x3, 2x2, 1x1 that cap at 1,300Mbps, 900Mbps and 450Mbps, respectively.

Technically, each spatial steam of the 802.11ac standard is about four times faster than that of the 802.11n standard, and therefore is much better for battery life since it doesn’t need to work as hard to deliver the same amount of data throughput. In real-world testing so far, with the same amount of streams, it has been found that 802.11ac is about three times the speed of Wireless-N which is still significant. The real world sustained speeds for wireless standards are always much lower than the theoretical speeds. This is partly because the testing had been conducted what are essentially lab conditions, where the environments are clean and completely free from interference.

On the same 5GHz band, 802.11ac devices are backward-compatible with Wireless-N and 802.11a devices. While 802.11ac is not available on the 2.4GHz band, for compatibility purposes, an 802.11ac router can also serve as a Wireless-N access point. All 802.11ac chips on the market support both 802.11ac and 802.11n Wi-Fi standards.