Back To 500 Mbit/s Wifi At Home – Thank you Radar!

In a previous post I wrote about installing a Wi-Fi repeater in my home and how I could then reach a sustainable data rate of over 800 Mbit/s. Very close to Gbit Ethernet! Unfortunately the connection was not stable. After a few days the repeater just stops working until rebooted. After experiencing this a couple of times I had a closer look to find out if this was a software instability or something else.

I turned out that the root cause is the weather radar detection feature. Weather radar has a higher priority on the upper channels of the 5 GHz band than Wi-Fi. As per the regulatory requirements, Wi-Fi access points, including repeaters, have to look out for such signals. If detected, operation in the channel has to cease. An alternative is to fall back to the lower part of the 5 GHz band and continue operation there. Unfortunately, this doesn’t work in my setup as the channel is set-up by the Access Point which does not detect the weather radar and just stays on the channel. Hence, connectivity to the repeater is broken.

So the solution to my problem was to lock the Wi-Fi access point’s 5 GHz channel to the lower part of the 5 GHz band. And here, unfortunately, I ‘only’ get around 500 Mbit/s out of the channel. I was a bit puzzled at first why performance should be so much lower there, as interference is not very high. The reason probably is that in this part of the band, the router is limited, again due to regulatory requirements, to a transmission power of 23 dBm (200 mW). In higher parts of the band, a transmission power of 30 dBm (1 Watt) can be used. That’s a big difference and could very well explain the performance difference! I don’t have a datasheet of my access point and of the repeater so I don’t know for sure if that’s the real reason. But I’d say it’s quite likely.