Mention "home Wi-Fi router" and you’ll probably think of a cheap device with cruddy performance. But dramatic changes are coming, with big boosts in bandwidth, thanks to two new Wi-Fi technologies.
Both beamforming and MU-MIMO (an acronym for the mouthful that is “multi-user, multiple input, multiple output”) are transformational technologies. We tested them in the new Linksys EA-7500, the company’s first small office/home office router to support the so-called Wave 2 technologies.
(For the record, “Wave 2” is a marketing and not a technical specification. The IEEE 802.11ac standards describe how beamforming and MU-MIMO must be implemented.)
The first of these technologies, beamforming, makes more efficient use of the radios in Wi-Fi routers. Before beamforming, Wi-Fi routers worked like light bulbs, with signals radiating in all directions. Problem is, signals only need to travel where Wi-Fi devices are – and that’s typically just a small part of the total coverage area.
With beamforming, Wi-Fi routers and and clients exchange information about their locations. Then, the router alters its phase and power for a better signal. The result: Far more efficient use of radio signals, faster forwarding, and possibly greater distances.
Beamforming comes in two flavors. With explicit beamforming, both client and Wi-Fi router share information about radio reception from their respective locations. This allows for the most efficient “steering” of signals between the Wi-Fi router and clients. Many recent devices, such as Apple smartphones and tablets made within the past two years, support explicit beamforming.
Even older clients may still benefit. With implicit beamforming, the Wi-Fi router steers signals based on its own measurements, without signal information from clients. Implicit beamforming doesn’t work as well as the explicit version, but some performance gains still are possible.
Beamforming makes possible a much bigger advance in Wi-Fi: MU-MIMO.
Until now, Wi-Fi routers have essentially been single-taskers, sending or receiving data from one device at a time. Earlier versions of the 802.11 standard, including 802.11n and Wave 1 versions of 802.11ac, described a multitasking method using “spatial streams” to carry on simultaneous conversations, but until now there wasn’t a standard method for talking with multiple clients at the same time. With MU-MIMO, now there is.
This is a really big deal, as it makes vastly more bandwidth available to wireless clients. For those old enough to remember, MU-MIMO is just as revolutionary as Ethernet switching was 20 years ago. Like switching, MU-MIMO moves networking away from the old shared-access, one-at-a-time model to a more capable system where multiple devices can speak simultaneously.
You weren’t around back when Ethernet switching took root? Then imagine moving from a single-lane country road to a big superhighway. Either way, it’s a big boost in capacity.
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