Webinar Recording - Wi-Fi in Education - Playbook for avoiding Wi-Fi detention

If you missed class, don’t worry; attendance wasn’t recorded, and doesn’t impact your  grade. The recording is available here: 

Recap: 

The Students: Joel Crane, Jerry Olla and Jussi Kiviniemi
The Professors: Mitch Dickey, Rowell Dionicio and Bryan Ward

Here are some of the notes from the lecture! 

1 AP Per Classroom 

• Used to be hotly debated, as using the blanket “1 AP per classroom” rule didn’t necessarily help designs meet their requirements or was a lazy requirement itself. 
• Today, as capacity and throughput requirements have increased, it usually makes quite a bit of sense to do a “1 AP per classroom” design. 
• Mitch typically sees 25-ish kids per classroom, and they all usually have a smartphone and Chromebook, making for about 50 devices per classroom (your mileage will vary). 
• When defining your network requirements, see what the design calls for. That just might end up being 1 AP per classroom. 
• Of course, controlling costs (especially if you’re an integrator serving customers) is important, so talk to your doctor to see if 1 AP per Classroom is right for you. 

• How may devices can an AP handle? It wildly depends, but Mitch usually says 50-75, and Bryan says 20 for 20 MHz channels, and about 35 for 40 MHz channels. But of course, it’s wildly dependent on a bunch of different factors, such as what applications are being used on the network. Your mileage is guaranteed to vary. 

20 MHz, or 40 MHz Channels? 

• Bryan likes to use 40 MHz channels until he can’t anymore. Usually, excessive co-channel interference drives him to back a site down to 20 MHz channels. 
• Usually, this is a site-wide decision, as clients tend to prefer APs configured to 40 MHz and will “stick” to them (and not roam back to the 20 MHz APs). It’s best to pick a configuration and use it site-wide. 
• Mixing spatial streams doesn’t seem to cause sticky clients or roaming issues, and most clients only have two spatial streams themselves, anyway. 

6 GHz Considerations 

• 6 GHz, being a higher frequency, is bound to cover a little bit less than 5 GHz. One AP per classroom makes sense for supporting the 6 GHz band. 

Where should we put AP’s in the Classroom? 

• Typically, the center of the classroom is the way to go. 
• If you can’t position the AP in the center, it’s probably not a big deal. Avoid corners, though. 

Floorplans and Making Friends with the Architect 

• Every building has architectural drawings that must be stamped and approved by your local government. They have to exist! It’s just a matter of finding out where they are. 
• Architectural drawings include a lot more than just the floorplan; they usually include a reflected ceiling plan, so you can see exactly what the ceiling design will look like. This can be very useful for a design in a school or on a university campus. 
• IT is now very mainstream, so architectural drawings usually include telecom drawings. 
• Architects always design walls! You can see the exact composition of the walls, which is very useful when building out wall types in Hamina Network Planner. 

• Section views are very useful for viewing the layout and configuration of auditoriums. You can see exactly what the seating, raised ceiling, and presenter area look like. 
• HVAC is also carefully designed ahead of time. 
• Plan to update the design multiple times, as the plan is likely to see multiple revisions during the process. 
• You don’t need to be an AutoCAD expert, just make friends with the architect! 
• Work with the architect to help them accomplish their goals. Ask questions like, “I don’t want to mess up your beautiful wood ceiling here with an access point. How can we serve Wi-Fi to the users, and meet the Wi-Fi design goals while maintaining the aesthetics of your building?” 

Grading Jussi’s Assignment: Requirements 

• When the profs graded Jussi’s design, he presented two requirements: GREEN EVERYWHERE, AND CHEAP! 
• His design ended up with two home grade routers for an auditorium that could hold several hundred people. 
• Professor Dickey noted that both routers were on the same channel, so there would be horrible co-channel contention (and this professor has reviews on Rate My Professors, saying that he has liked single-channel architectures in the past). 
• Professor Dionicio and Dr. Ward gave Jussi and F-, recommending that he do proper requirement scoping next time. 

• The requirements need to factor in how many users there will be, and what applications they’ll need to run. For example, Zoom has clearly specified throughput requirements.  
• Those two pieces of information should drive the requirements. Then, he should design a network that meets the requirements. 

Grading Joel’s Assignment: Capacity 

• Joel did a design for a high school, but only placed one AP every three classrooms or so. 
• At 50 clients per classroom, that’s about 150 clients per AP. 

• Don’t forget about the thermostats and iPads in the hallway that are being used for digital signage. 
• Rowell has had 300 clients work on one AP by telling students to not use Facebook or Instagram 
• Rowell has sat in classes and counted how many people are using YouTube. Meeting requirements usually isn’t enough, because people use the Wi-Fi for other stuff 
• Even worse, Joel tried to cover a 315-person auditorium with only one AP. 
• That’s fine for just the sound guy, but not for an entire auditorium. He should have used multiple AP’s with directional antennas. 

• Joel’s grade: F-. Yep, he’s going to have to re-take this class. Again. 

Grading Jerry’s Assignment 

• Somehow, Jerry got out of it. How did that happen?! 
  

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