What's next for Wi-Fi? A second wave of 802.11ac devices, and then: 802.11ax

While you consider which 802.11ac router to buy, the industry is working hard to render it obsolete

Now that blazing-fast routers based on the IEEE 802.11ac standard are finally entering the mainstream, intrepid engineers are busily cooking up all-new hardware that will make that gear's performance seem quaint by comparison.

That's not to say 802.11ac is about to fall by the wayside--after all, the IEEE didn't officially ratify the standard until December 2013. It's just that the chipsets capable of delivering all the features and performance in that standard are still in development.

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You see, most of the first wave of 802.11ac routers were based on draft versions of the 802.11ac standard. While some newer routers, such as Netgear's six-antenna Nighthawk X6, are implementing cool tricks to squeeze more performance from that technology, a second wave of 802.11ac routers will hit the beach in early 2015.

These devices support a number of optional features in that standard that will deliver even higher wireless performance. At the same time, new and complementary wireless technologies designed for specialized applications will also appear.

But there's no point in trying to cheat obsolescence by putting off your next router purchase: The industry is already hard at work developing the successor to 802.11ac. Let's dive into what's next for Wi-Fi.

The two-party system

The IEEE (Institute of Electrical and Electronics Engineers) defines Wi-Fi standards such as 802.11ac and the older 802.11n. The Wi-Fi Alliance (an association of companies that build wireless-networking devices) certifies that the hardware based on those standards will work together.

Wi-Fi Alliance certification is not a requirement (manufacturers must pay for the designation), but it can be reassuring to consumers, especially in the early days. That's because the IEEE can take several years to finalize its standards (it started working on 802.11ac in 2008 and finished in late 2013). Manufacturers often don't want to wait, so they'll bring new products to market as soon as the ink dries on an early draft. Buffalo shipped the first 802.11ac router in 2012, but the Wi-Fi Alliance didn't launch its first 802.11ac certification program until mid 2013.

SU-MIMO (single-user multiple input/multiple output) technology was one of the hallmarks of the older 802.11n standard. It allowed multiple spatial streams to be transmitted to a single client. This technology was carried over to the 802.11ac standard, which added a more-powerful modulation technique (among other things) to deliver a maximum physical link rate of 433Mbps per spatial stream.

Since it can support up to three such streams simultaneously, a Wave 1 802.11ac router can send and receive data at a maximum physical link rate of 1.3Gbps. Compare that to 802.11n routers, which provide up to three spatial streams with maximum physical link rates of just 150Mbps each (for aggregate throughput of just 450Mbps).

Wave 2 802.11ac routers will arrive sometime in 2015. These devices will also operate on the less-crowded 5GHz frequency band, but they'll take advantage of several optional elements of the 802.11ac standard: First, they'll support a feature called MU-MIMO (multi-user multiple input/multiple output), which allows them to transmit multiple spatial streams to multiple clients simultaneously.

Second, they'll bond multiple channels on the 5GHz frequency band to create a single channel that provides 160MHz of bandwidth (Wave 1 802.11ac routers can also bond 5GHz channels, but the bonded channel is only 80MHz wide). Third, where 802.11n and Wave 1 802.11ac routers support a maximum of three spatial streams, Wave 2 802.11ac routers will potentially support up to eight spatial streams.

Using some combination of wider channels or additional spatial streams (there isn't enough available bandwidth to do both), improved beamforming, and other techniques, Wave 2 802.11ac routers will deliver maximum physical link rates in the range of 7- to 10Gbps. Quantenna Communications announced its first Wave 2 802.11ac chipset last April.

The next new Wi-Fi: IEEE 802.11ax

In a recent briefing, the Wi-Fi Alliance's VP of Technology Greg Ennis said the IEEE anticipates the 802.11ac standard will be succeeded by 802.11ax. While the standards body doesn't expect to ratify it before March 2019, products based on a draft of the standard could reach the market as early as 2016--just as we saw draft-802.11n and draft-802.11ac products before those standards were officially ratified.

One of the top objectives of 802.11ax, according to Ennis, is to quadruple wireless speed to individual network clients--not just to increase the speed of the network overall. The Chinese manufacturer Huawei, which has engineers in the IEEE 802.11ax working group, has already reported Wi-Fi connection speeds up to 10.53Gbps on the 5GHz frequency band.

Ennis said the 802.11ax standard will improve Wi-Fi performance in environments with high numbers of users, such as hotspots in public venues. This will be accomplished by using the available spectrum more efficiently, doing a better job of managing interference, and making enhancements to underlying protocols such as medium access control (MAC) data communication. This should make public Wi-Fi hotspots faster and more reliable.

The 802.11ax standard will also use orthogonal frequency-division multiple access (OFDMA) to boost the amount of data the router can transmit. Like OFDM (orthogonal frequency-division multiplexing), OFDMA encodes data on multiple sub-carrier frequencies--essentially packing more data into the same amount of air space. The "multiple access" in OFDMA describes a means of assigning subsets of those sub-carrier frequencies to individual users.

The complementary standards

While one segment of the IEEE works to define the successor to 802.11ac, other factions work on two complementary wireless-networking standards that address other needs. The IEEE 802.11ad standard uses unlicensed spectrum in the 60GHz band to build fast short-range wireless networks with peak transmission rates of around 7Gbps.

There are two major drawbacks to transmitting data at 60GHz: One is that the extremely short waves have difficulty penetrating walls. Another is that oxygen molecules begin to absorb electromagnetic energy at 60GHz.

That explains why the relatively few 60GHz products to reach the market so far are designed to operate at very short range, or within a single room. Dell's Wireless Dock 5000 is a good example of the former, and the DVDO Air--which streams HD audio and video from a Blu-ray player to a video projector without a cable--is a great example of the latter.

The Wi-Fi Alliance announced its 802.11ad certification program late last year. The group will stamp interoperable 802.11ad products as "WiGig Certified."

The IEEE 802.11ah standard, meanwhile, literally resides at the opposite end of the spectrum. Operating in the unlicensed 900MHz frequency band, a wireless network based on this would easily penetrate walls, but it wouldn't deliver a lot of bandwidth: anywhere from 100Kbps to 40Mbps. One use case might be for sensors and probes in connected home or commercial buildings, but the IEEE isn't expected to ratify the standard until January, 2016. 802.11ah could be considered a competitor to the Z-Wave and ZigBee protocols in the Internet of Things space.

What with 802.11ac, -ad, and -ax, the future of Wi-Fi looks a lot like alphabet soup. But it's really the evolution of Wi-Fi into standards that fit the demands of new generations of wirelessly connected devices. When those new generations contain everything from enterprise printers to egg timers, you can bet there'll be needs for all the flavors of Wi-Fi coming down the pike.

This story, "What's next for Wi-Fi? A second wave of 802.11ac devices, and then: 802.11ax" was originally published by PCWorld .

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