Gigabit Wi-Fi is here, but device makers can go faster if they want to

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http://arstechnica.com/information-technology/2013/06/gigabit-wi-fi-is-here-but-device-makers-can-go-faster-if-they-want-to/

The Wi-Fi Alliance has begun certifying network hardware, chips, smartphones, PCs, and tablets for the new "Gigabit Wi-Fi" standard. But while the certification program covers hardware with speeds of up to 1.3Gbps, vendors can make equipment that goes faster—and at least one already has.

The 802.11ac certification program, announced today, covers equipment pushing 1.3Gbps of data by using three spatial streams of 433Mbps each. This is the speed that has been supported in chips and routers for more than a year. Vendors got an early start with 802.11ac because the standard has been stable for a while, even though certification hadn't begun.

But the real-world limit is not 1.3Gbps. We saw recently that chipmaker Quantenna unveiled 802.11ac Wi-Fi chips that push 1.7Gbps of data by using four wireless streams instead of three. This is possible because while 11ac certification covers only three spatial streams, the 802.11ac standard allows more than that.

"At this point in time, what the market is looking for is three spatial streams," Wi-Fi Alliance Marketing Manager Kevin Robinson told Ars. "Other vendors can go above and beyond what we certify."

The 802.11ac standard has technically not even been ratified by the IEEE Standards Association yet. "The IEEE standard is very mature and the Wi-Fi Alliance has been able to look at that standard and determine what are the most beneficial features for the market today and release a certification program that releases those features to users ahead of the ratification of the standard," Robinson said. The process is very much similar to what occurred with 802.11n, the previous Wi-Fi standard.

802.11n throughput for a single stream topped out at 150Mbps. Robinson noted that certified 11ac devices nearly triple that in large part because the standard uses channels of up to 80MHz instead of 40MHz.

802.11ac includes optional features allowing up to eight spatial streams and channels of up to 160MHz. A white paper by Wi-Fi vendor Xirrus says that "support for up to 8 spatial streams and 160MHz channels in future versions of 802.11ac takes the maximum data rates up to 6.9Gbps."

A multi-gigabit, tri-band future

Even if 802.11ac never goes beyond 1.7Gpbs, that doesn't mean Wi-Fi speeds will stop there. That's because of the 802.11ad standard, which supports up to 7Gbps on the 60GHz band. The 60GHz transmissions are easily blocked by walls, so they're only useful for connecting devices in the same room. But 11ad will help support tri-band devices that also use the 2.4GHz and 5GHz bands for 802.11n and 802.11ac, falling back from 60GHz to the lower frequencies when 11ad connections are blocked. 802.11ad certification will begin sometime next year, but a small number of products are already on the market.

With 1.3Gbps, the Wi-Fi Alliance said HD movies could be transferred to a tablet in less than four minutes, and three HD movies could be streamed at once.