What Opportunities And Challenges Come With 802.11ax?
This series from wireless expert Craig Mathias of Farpoint Group will provide the background and context you need to understand the features, benefits, and positioning of 802.11ax, what it means to organizational users, why it will eventually achieve dominance, and – very importantly – when.
It’s important to point out up front that the IEEE 802.11ax standard is still in development – we don’t expect the very comprehensive process involved to be complete until late 2018 or early 2019. This implies two key facts:
- First, we can’t say for sure exactly what will be in the final standard, although we have a pretty good idea at present.
- And, second, rest assured that you’ll see plenty of pre-standard products that will be very close to the final standard, and, as has historically been the case, likely updateable to compliance with the standard and the subsequent Wi-Fi specification for interoperability, and likely with just a firmware upgrade.
As for the development of the standard, the IEEE standards process is among the most open and rigorous conceivable, and has been well-tested over decades with many different technologies. You can find a pretty good list of IEEE standards here. Most networking standards are developed under IEEE 802, and wireless under 802.11. Official information on 802.11ax can be found here.
While the IEEE itself is primarily an engineering professional society with strict membership requirements (author’s note: I’m an IEEE member), this is not to say that politics doesn’t play a role in the development of new standards. They do, and are one of the key reasons why the development of any given standard can take many years.
So-called ad-hoc “special interest groups” (SIGs) pushing a particular set of technologies and hoping to gain a time-to-market advantage (building .11 chips is very, very complex) often slow the process via procedural maneuvers. Such is again the case with .11ax.
But this is not to say that the underlying technologies are the easy part – far from it.
Ignoring procedure and politics, 802.11ax is, as we previously noted, more evolutionary than revolutionary. The current draft (which, by the way, recently failed its first procedural vote, with over 7,000 comments yet to be resolved) builds on two key technologies: orthogonal frequency-division multiplexing (OFDM, which has been ion the standard since 802.11g), and multiple-input/multiple-output (MIMO, which has been around since 802.11n).
OFDM breaks a single high-speed data stream into many simultaneous slow-speed data streams, thereby making implementation easier and improving reliability, and MIMO takes advantage of space in addition to frequency and time – adding a third “spatial” dimension that blows the lid off of previous performance limitations. We believe at present that up to eight MIMO streams will be specified in .11ax, as is the case with 802.11ac, with 4-1201 Mbps per stream – hence up to 10 Gbps.
The latest “Wave 2” (an informal term indicating the inclusion of features in the standard that were left out of initial products) incarnation of 802.11ac includes an exciting feature known as multi-user MIMO (MU-MIMO). This enables distinct data streams to be transmitted from an AP to multiple clients simultaneously – in a single transmission, thereby taking advantage of the huge supply of throughput available in .11ac but underutilized by the typically lower level of demand of an individual client.
802.11ax will likely include MU-MIMO from the client to the AP – in other words, multiple stations transmitting distinct data streams simultaneously. Pretty cool. And 802.11ax similarly evolves OFDM from a multiplexing technique into a multiple-access strategy called, cleverly enough, orthogonal frequency division multiple access (OFDMA). The difference is subtle, but enables operating installations to assign a given number of those lower-speed data streams to a given user.
Whereas 802.11ac was specified only in the 5-GHz. bands, 802.11ax will also use 2.4 GHz spectrum.Whereas 802.11ac was specified only in the 5-GHz. bands, 802.11ax will also use 2.4 GHz spectrum Yes, there’s relatively little bandwidth here, but it’s hoped that any technologies before 802.11n (.11n can also operate in both bands) will finally see a sunset.
Backwards compatibility in 802.11ax should enable support for .11n where required, but will also apply much more efficient technology to this spectrum.
There are a number of other technical improvements, but also a few challenges remaining as well. These include forms factor, as was noted above. Eight-stream configurations have yet to see service in .11ac, due to the number of antennas required. Two or in some case three streams seems to be a reasonable upper bound for client devices, but two to three Gbps ain’t bad regardless, especially with MU-MIMO picking up any slack.
Power consumption is always a concern, and complex processing eats electrons. And, for now, at least: spectrum. While there’s always hope that more unlicensed spectrum will become available, we can’t count on such. At this point, our best advice is to phase out all devices operating on standards before 802.11n, to put in place an upgrade plan, and to reserve a few channels just for .11ax in order to get the best possible performance. Still, we’ve got plenty of time before these issues become critical.
And we’ve even got a few early chipsets beginning to appear, giving system designers the opportunity to begin to acquire familiarity with the advanced technologies involved. Both Qualcomm and Quantenna, already leaders with high-performance Wi-Fi chipsets, have announced albeit limited and pre-standard implementations.
So even as we have time before .11ax arrives, it’s not too early to begin the planning process. We’ll cover the key points here next time.