Wi-Fi gets multi-gigabit, multi-user boost upgrades to 802.11ac
The Wi-Fi Alliance industry group is now certifying products that can deliver multi-gigabit speeds and improve coverage in dense networks by delivering data to multiple devices simultaneously.
The new certification program, announced today, focuses on the so-called “Wave 2” features of the 802.11ac specification. 802.11ac is a few years old, but it includes several important features that were not available at launch. One such feature is MU-MIMO (multi-user, multiple-input, and multiple-output), which we wrote a feature on in May 2014. MU-MIMO is powered by multi-user beamforming technology that lets wireless access points send data streams to at least three users simultaneously. Without MU-MIMO, routers stream to just one device at a time but switch between them very fast so that users don’t notice a slowdown except when lots of devices are on the network.
With the 80MHz channels supported in 802.11ac Wave 1, each data stream could provide up to 433Mbps and, when coupled with MU-MIMO routers, can send up to 433Mbps to at least three users simultaneously for a total of 1.3Gbps. But in addition to supporting MU-MIMO, Wave 2 also doubles the maximum channel bandwidth from 80MHz to 160MHz, boosting the potential throughput of each stream to 866Mbps. Wave 2 also supports four spatial streams instead of three, further boosting the theoretical maximum capacity. Technically, 802.11ac supports up to eight streams, but the certification program is still at four. Delivering eight streams with these data rates would use a lot of electricity.
On top of MU-MIMO, wider channels, and more streams, the Wi-Fi Alliance says Wave 2 features now being certified bring “support for a greater number of available channels in 5GHz,” a change that “makes more efficient use of available spectrum and reduces interference and congestion by minimizing the number of networks operating on overlapping channels.”
You may have already noticed routers supporting some of these features, since the specification details have been available for a few years. In fact, routers with MU-MIMO started appearing in July 2014, and you can find routers that use 160MHz channels. The certification program takes a while to catch up with real-world implementations, but it ensures compatibility between devices and may spur faster adoption by vendors. End-user devices such as phones, tablets, and laptops must also be updated to take advantage of new features such as MU-MIMO.
Wave 2 certification has started with a few products that form a test bed against which other products are tested for interoperability. The test bed products include chips from Broadcom, Marvell, Quantenna, and Qualcomm. They also include a MediaTek reference design for access points.