Thursday, March 24, 2016

WiFi technology - from Beamforming to MU-MIMO

Modern WiFi routers come with new selling features such as Beamforming and even MU-MIMO. What are these new features about? Will your home and/or office WiFi network be benefited with these new features? I also have the same questions, and here is the answer from my research.

Beamforming Technology

Beamforming is a kind of wireless transmission method introduced to reduce interference and improve the reliability of WiFi signal. It is adapted in the 5th generation WiFi standard 802.11ac.

Beamforming is based on Digital Signal Processing (DSP) logic and Multiple Input Multiple Output (MIMO) technology. Using a procedure called channel calibration or channel sounding, it changes the phase and relative amplitude of the signal, creating a constructive interference and destructive interference to make the signal in preferred direction stronger and others weaker.

In this way, the WiFi router can focus the signal towards the direction of your WiFi devices connected to it, making the wireless connection stronger, more stable, and further reaching. As effective WLAN bandwidth degrades with weaker signal and longer distance, beamforming can help to reduce this degrading effect, therefore making the network faster.

However, bear in mind that your WLAN network is still limited by the maximum supported bandwidth of the WiFi router and the WiFi client, and your Internet bandwidth is still limited by the maximum bandwidth of your subscription package. Your network still won't be faster than these limitation.

Certain 802.11n routers and devices also support beamforming, but unlike 802.11ac, there is no common standard with beamforming in wireless-N.

In order to benefit from the beamforming technology, both your wireless router and wireless device (computer, tablet, handphone, smart TV, etc.) must support this technology. If they are of wireless-N device, then the beamforming of the wireless client must compatible with the wireless router as well, preferably from the same brand or manufacturer.

Beamforming is standardized in wireless-AC, but that does not mean that all wireless-AC has this feature. You have to ensure your wireless-AC device comes with beamforming technology to get its benefit.


Traditional wireless router or access point, even with MIMO technology, can only serve one wireless client at one time. If it is connected to multiple WiFi devices, each of the devices take turn to be served. The more wireless devices you connect to the WiFi router, the less bandwidth is available for each one of them.
Multiuser MIMO (MU-MIMO) is introduced in the 5th generation WiFi standard 802.11ac. In a wireless system that uses MU-MIMO, the router can direct separate streams of bandwidth to up to 4 different devices simultaneously, as long as the devices are also able to use MU-MIMO technology.

For a MU-MIMO router with 4 antennas, each antenna can serve an individual MU-MIMO supported wireless device. Each of these devices can utilize the full WLAN bandwidth supported by the router.

If there are more devices, then the 5th onwards still need to share antenna with other device.

So, one MU-MIMO router is equivalent to 4 virtual MIMO routers, in the condition that the wireless clients connected to it also support MU-MIMO technology.

What if your wireless device is not supporting MU-MIMO? The router is backward compatible to act as single-user MIMO (SU-MIMO) router just like the older MIMO, and you won't enjoy the benefit of MU-MIMO in this case.


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