A couple of days (now weeks) ago I had the opportunity to attend an Aerohive roadshow that was focused on the new 802.11ax standard. My reason for attending was to listen to Aerohive’s “Senior Technical Evangelist”, the great David Coleman, CWNE #4 and also the co-author of the Sybex CWNA Study Guide, of which the 5th edition was recently released. If you haven’t seen it, just take a gander at it. All told, the page count is north of 1,000 pages! Anyways, I went because I wanted to hear more about the new 802.11ax standard, listen to Mr. Coleman, and get out of the office, pretty much in that order. It’s OK, I even put that on my comment card so this isn’t news to anyone involved.
As an event, it was very well done. My previous experience with Aerohive was limited to knowing they had a “HiveManager” but not knowing anything about it and their little stress ball “bees” that my granddaughter loves to play with. My biggest fear was that the whole discussion was going to de-evolve into a marketing talk about Aerohive, but with David Coleman involved, I was pleasantly surprised. David is super smart, and he was able to keep the topic centered on the IEEE standard (that as of November 2018 hasn’t been ratified yet) with just enough marketing to keep the people footing the bill happy. I was also happy to see that there were administrators of other vendors present; all there just to learn about 802.11ax. Kudos to Aerohive for keeping the proper mix of technical and marketing, I never felt the pressure of a sales pitch, just good ol’ fashioned arguing about the finer points of Wi-Fi!
Since I was there primarily to learn more about 802.11ax, I was happy with the technical part of the afternoon. I also heard other attendees say the same thing so I know it wasn’t just me that thought that. My biggest takeaways from what I learned, and not just what I knew already is this:
- 802.11ax is officially known as “802.11ax High Efficiency Wi-Fi.” I knew that while marketing people were banging away at the 1024 QAM modulation scheme that provides a jillion bytes per second of throughput the real improvement was centered around improving spectral efficiency. The fact that someone was smart enough to to include that in the name was a pleasant surprise.
- Resource Units (RU’s) are at the heart of Orthogonal Frequency Division Multiple Access (OFDMA) which is the 802.11 change that allows 802.11ax to be highly efficient. This was “borrowed” directly from how LTE works, so it’s not like this is a new concept in the RF world, just in the 802.11 world. As far as the standard goes, the smallest allocation of these Resource Units is 26 subcarriers (or tones). I’m not going to get into subcarriers here but I will include a link at the end if you want to read more. It’s nice to know that there is a standard to point to when vendors start to stray from that to improve their marketing jargon. Why 26 subcarriers being the smallest resource units allowed is important because in the future as this will be akin to the 20 MHz channel width that we know today. When looking at the chart above, it looks similar to what we know about the channel graphs that go from 20 MHz wide channels to 160 MHz wide channels. Hopefully this reinforces the idea that 802.11ax is about going smaller to better utilize the spectrum, not going bigger.
- There are some new frames that have been introduced in the 802.11ax standard called “trigger frames.” On the surface these trigger frames seem innocuous but upon deeper inspection, you come to find out that these new frames actually provide a level of control that previously hasn’t been seen in previous 802.11 standards. AP’s can now use these trigger frames to learn what type of data, and how much of it, a client wants to send so it can calculate how many Resource Units the AP needs to allocate to each client and make a plan on who it can combine together into a single time slot. This is at the heart of the high efficiency and I can’t wait to dig deeper into these trigger frames. All told there are 7 different types of these new trigger frames and I believe will provide additional features going forward. That’s mere speculation on my part, but I can see how these frames could be leveraged once 802.11ax hits the mainstream.
- BSS “Coloring“. This will come as a surprise to no one, but “coloring” is a marketing term, not a technical term. There are actually numbers for each “color” but it’s easy to see why they added color to the slide so it’s easier to show non-techie people. What coloring actually does is focus on spatial reuse and the Clear Channel Assessment (CCA) that exists in the 802.11 today. This new coloring introduces a new “color bit” into the PHY header that can only be interpreted by 802.11ax clients. This also introduces two new terms to the lexicon known as intra-BSS and inter-BSS transmissions. Intra-BSS transmissions are both on the same color so nothing changes from what happens today. Inter-BSS transmissions are when a device determines that what it heard was actually from a different color BSS and treats the medium as busy “only for the time it took to determine the color bit was different.” Understanding this from a textbook perspective is one thing, it will be really interesting to see what happens when this is deployed in real world scenarios. Stay tuned in 18 months when we finally have AP’s AND clients available to test this one out!
- While PoE is nothing new to WLAN folks, the new AP’s that are being announced are coming with new bells and whistles and are going to require more power to operate. What has just now started to become an issue with 802.11ac AP’s is only going to get worse. Designers and engineers are now going to have to pay special attention to power requirements per port, total power per switch, power supplies for the switch, and then UPS requirements for these new higher power demands on the switches. If you have gotten rusty on your understanding of Ohm’s law, it’s time to break that out and dust it off!
I knew this couldn’t be avoided, but was happy that it was kept at a respectable level. If you are avoiding going to this because you don’t want to sit through a bunch of marketing, that’s a mistake. Don’t get me wrong, it’s there because someone has to pay for it, but David does a good job keeping it from being overwhelming.
One of the things that was interesting to see was the mounting solution that Aerohive has. I am a big fan of vendors who pay attention to the little things like mounting. You don’t really understand why until you are standing on the top step of a 10 foot step ladder at 4 AM trying to hang the last AP before you are shut down and some hokey mounting solution slows you down. It’s frustrating and I always like to look at that when I can.
The other thing I learned about Aerohive is they are going to support WPA3 SAE (the “upgraded” WPA2-PSK) before the end of 2018 and allow older hardware to support it with a code upgrade. WPA3 Enterprise will also be supported but sadly Opportunistic Wireless Encryption will not be something Aerohive will support unless it becomes mandatory.
I know, I talked with David Coleman about this at length both before and after his presentation, and we parted agreeing to disagree. While I don’t like the stance that Aerohive has taken in this regard, at least I know their reasoning. Aerohive supports PPSK and feels that this is the best option for guest Wi-Fi security options. For 95% of the applications, they are right. PPSK is a better option and it’s something they support today. Why re-invent the wheel? Sadly, I fall into the 5%. I get it, I ALWAYS fall into that 5% outlier so I fight the uphill battle everyday. I know that in a perfect world every vendor would support every option, but it ain’t happening.
While I won’t advocate that everyone should run out and purchase Aerohive gear to deploy everywhere (simply because I am firmly in the “It Depends™” camp) it was a pleasant surprise to learn about Aerohive, their gear, and to meet David Coleman in person. Another pleasant surprise, albeit one I should have expected, was meeting some folks in my area that also work in Wi-Fi. Sometimes, sitting out here where I do, I forget there are other folks who do Wi-Fi for a living in the city I work in. Honestly, look at a map, where I work is technically “in the city.” I will give you that it takes some crazy gerrymandering map work to make it happen, but it is in the city.
Now, if you want to learn more, here are some links that I promised earlier.
- Read more about David Coleman’s take on 802.11ax.
- Get the Aerohive 802.11ax book for dummies.
- Learn more about Aerohive and their gear here.
802.11ax is a thing (WiFi 6) so if you don’t take advantage of great resources like this then you are really missing out!