Wi-Fi Woes
In theory, modern Wi-Fi Access Points (APs) should be able to provide Gigabit speeds and several hundred metres range. So why are many disappointed with what they get? Sadly, Wi-Fi is not plug and play—at least not in a shared environment with competing devices. Users need to understand a few basics, some of which are counter-intuitive.
Sharing

Everything about 802.11 Wi-Fi is “shared”—especially bandwidth. There are two bands—one at 2.4GHz and the other at 5GHz. Nowadays, only older (legacy) equipment is confined to 2.4GHz. There is not much capacity at 2.4GHz (which has just 3 channels, each 5MHz wide). If you want capacity and speed, go for the 5GHz band (which has 24 channels, each 20MHz wide).
One client we worked with had a food court served by two APs on the ceiling 10m above the tables. To increase capacity they added a third and they were surprised that capacity dropped. The issue was that several food court vendors ran their own Wi-Fi—making all the APs fight for channels. APs detect other APs trying to use the same channel, so they will either pick a different channel or reduce power to stop interference. The two APs originally installed grabbed 2 of the 3 channels and the food vendors ended up sharing the third—all worked well. Adding a third ceiling AP caused it to grab the same channel as one of the other ceiling APs, so both reduced power. Lower power equals less range, so the APs couldn’t reach the floor anymore, hence degraded service.
Legacy Users
The oldest Wi-Fi still in use is 802.11b, which dates back to 1999 and provides speeds up to 11MBit/s. The newest 6th gen technology (802.11ax) provides access speeds in the Gigabit/s range.
APs can be configured to allow any Wi-Fi standard to connect—or they can be configured to block older and slower standards. That is worth doing if speed (or capacity) is important because the Wi-Fi protocol slows down to the speed of the slowest user—no chance of GB/s speeds if you have an 802.11b user on the AP.
We worked with some airports that were having issues being unable to get the rated capacity. The problem turned out to be that Wi-Fi was shared by travellers waiting to board at a gate and by the aircraft that had just docked. Airlines use Wi-Fi as a simple way to reload their entertainment systems between flights. However, newer Wi-Fi systems are not certified for aviation use so the aircraft were restricted to 802.11b. The solution was to install APs outside for the aircraft and inside for the travellers—with the latter set to block legacy speeds.
Radio Illumination
Think of a Wi-Fi AP like a floodlight: you need to point it in the general direction of the users. One client we worked with was having issues that turned out to be caused by their electrical installer: they had installed the APs upside down, so Wi-Fi coverage was only great if the users were on the ceiling.
Recommendations
- Make sure you site the APs so they “illuminate” where users are located and keep them close to users.
- If range is not an issue, focus on the 5GHz band. For best performance, turn off the 2.4GHz radios.
- Unless you must serve legacy users (like 802.11b), set all APs to serve modern standards only. If you need to support legacy users, set up separate APs specifically for them.
If you’d like to comment on this article or explore these ideas further, contact me at peter.
This article was published in the
September 2022
edition of The TMC Advisor
- ISSN 2369-663X Volume:9 Issue:4
©2022 TMC Consulting