I’m at 54, how about you? (multi-part series on a 54Mbps and roaming)

A couple years back, maybe more, I did this–changed a setting to 54Mbps. My office wireless network is set at 54Mbps minimum supported rate. I said heck why not do 54 and see what happens. OK, for the details of what my network is running and why. First off, we run Cisco Meraki wireless, it does exactly what I want and expect. Our network consists of simple L2/L3 designs, pretty cookie-cutter, darn near everything is Cloud based. With being Cloud based we just need WAN access. We have roughly 18 VLANs, even for a few simple things like printers, those go on a dedicated VLAN. Also, I take the approach of “if it has a network port, make it wired”. Along with isolating devices with VLANs, we also run an entire Apple environment, i.e. all iPhone, iPads and MacBooks(generally within 24 months of the latest physical device released–for the most part all latest-gen). With this approach, I don’t have to go around guessing about what wireless card driver versions are installed, did Windows 7/10 overwrite a newer driver etc… (yes, I did mention Windows 7, we have some legal software that is great at the legal process-but sucks otherwise-and it works well on Windows 7).

Now for our physical Access Point placement, I did not have access to Ekahau or any predictive mapping software when our office was planned. But, I did know the walking patterns and how our lawyers operate(I call this part TACO(I’ll blog about that later) or basically Chapter 2 in the Certitrek CWDP-302 book). They generally *do not roam*. What?? What do you mean?

Let me explain a little on that. First off, people enter the first floor, access the elevator for the second floor(our office is the entire second floor of a three story building). I have an access point roughly 10 feet from the elevator, that is pretty much meant to get the device connected. Hardly any usage on that AP is done, maybe a quick email or two if the elevator is slow that day. That AP is also on the opposite side of the building that the most used offices are. Also, I know that the mobile devices are usually tossed in a pocket or backpack during this time. Sometimes, those devices are not even touched until sitting on the desk in the person’s office. And, in that case they will connect to the AP that is right outside their office.

Knowing how the devices are used, I placed the Access Points in relation to the office usage walking patterns. huh? Basically, I knew how people will walk around in the office, how they will be using a mobile device and what would be used on that mobile device. Lucky for me, I know that our mobiles devices are used for consumption. Lots of PDFs(mostly looking at one or two that are 100’s of pages), along with some Words Docs, hardly any VoIP and/or video used in a “walking around” sense. Very little Facetime/Video, however lots of cell calling(but that’s not my problem).

Now that you have a little background of our network. You can see why I’m forcing a minimum supported rate(see pages 300-301 of Sybex CWNA-106 book, also page 218 for OFDM) of 54Mbps. And, I also know that all of our devices are 802.11ac.

Now comes the roaming part, which we really do not do. Since we run at 54, and know that the our devices will be very close, roughly 20-23 feet lines-of-sight propagation to the Access Point(if not closer). They *should* not have too much of an issue with decoding the higher modulation rate(see pages 640-643 Sybex CWNA-106).

Now, this is not a perfect theory of why this works for us, our office is all concrete floors and ceilings. with lots of lines-of-sight propagation to other Access Points.

However, I’m pretty sure we have a Near/Far issue due to our AP layout, think of it as as big “L” shape, with lots of metal and concrete walls, sitting in the “arm” of the “L”.

Or……are we just hitting the point of demodulation issues on that far away AP, since we’re at 54? Stay tuned for a little more details on that in the next blog post.

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