I’m not sure where the quote is from, but it is a perfect analogy for why I truly enjoy attending Aruba’s Atmosphere conference every year.
I’ve been on a nearly 20-year journey learning new things about Wi-Fi on a nearly daily basis. The WLAN industry is a dynamic and ever-challenging environment with upgrades, more complexity and new technology being added every single year. Yet, much of the basics and fundamentals haven’t changed since 802.11 ‘classic’ was first introduced with only 1-megabit-per-second data rates.
My personal experience at Aruba Atmosphere 2019 was another chance to sit and learn at the feet of folks way smarter and more accomplished.
Last year, I had the chance to learn from Eric Johnson’s presentation on Wi-Fi basics (by the way, he teaches it every year, and everyone needs to sit in this course). One item of note was his showing with hard math the “Fallacy of Matching Transmitter Power of AP and Client” – loved it!
Eric teaches using lots of visuals. His style is to allow students to seethe complex math that is at the base of all Wi-Fi. So, this type of delivery appeals to my visual learning style a lot.
Understanding the Magic of Spatial Streams
In this year’s session on Advanced Wi-Fi: 802.11 Modulation and Antenna Techniques, Eric went a bit deeper into some of the how’s and why’s of the magic behind 802.11.
From previous sessions with various folks, I’d come to learn of a new analysis that allows one to visualize the reflections and multipath necessary for spatial streams. With great anticipation I hung around for the last session of the last day to hear the repeat of the advanced RF course.
Here’s a sample of the visual depiction of spatial streams.
There are some software and algorithms working in the background, with a room setup with certain parameters, AP height, client device height and wall reflection factors. Then the client device is moved through the area in a raster process capturing the signals and reflected signals. (Darker is better in these pictures).
Omni antenna vs. downtilt omni antenna:
The first one I’ll share is showing the differences between an omni antenna and a downtilt omni antenna.
Note: the one on the left is the omni, and the one on the right depicts a down-tilt omni as noted with the extra antenna pattern.
Comparing 4×4 AP and 2×2 AP going to the same device:
The one I really appreciated was the comparisons between a 4×4 AP and a 2×2 AP going to the exact same client device.
There have been lots of other presentations showing how more radio chains allows for higher and more consistent data rates, even when a lower capable client. (As in 4×4 APs outperform 3×3 and 2×2 APs even when connected to a 1×1 or 2×2 client device.) But the visual from this presentation make it very obvious how much better 4×4 APs are for providing spatial streams to 2×2 clients. Don’t just take my word on this, though. Check out the visuals!
Note: the omni antenna in the center in the left graphic, and the omni antenna is moved up and to the right (where the red dot is located) is on the right frame.
Now, then the same client, but with a 4×4 access point instead of a 2×2.
I can’t say I totally understand everything I saw at Aruba Atmosphere, but it is great to know there are many more smart folks out there working on cutting edge issues, and still deign to come down and talk with the rest of the rank and file of the Wi-Fi community.
I, for one, am planning on attending and learning from experts and other Airheads at future Aruba Atmosphere conferences.