- Posted by IPTel Solutions
- On March 2, 2019
- 0 Comments
One of the more common questions I get asked, is: “Why would you want to use power caps to restrict the maximum power an access point can transmit at?”
Surely if the AP can transmit at a higher power, that’s better right? It will give better coverage at a higher power and so why pay for more APs? Makes sense doesn’t it? From a superficial level it does – but actually when you’re supporting lower power devices it doesn’t.
Five years ago, most people only ever connected laptops. Nice big batteries, nice big antennas, don’t roam very much in operation.
Coverage tended to be pretty sparse in terms of AP density and although everyone noticed the coverage wasn’t that great, it was good enough.
this earlier blog, describing this).Yes – its strange, but not all channels are equal (see
So, what are you left with? If you spark up your network and don’t have enough AP density, the APs will run at maximum power. On 5GHz (channel dependant as I say), some will be 25mW and some a whopping 200mW.
Let’s look at how this would look if those APs were a group of people in a room: you’d have some people transmitting whispering right next to people with a megaphone shouting.
Even right next to the guy whispering, the guy with the megaphone is going to drown him out. This is just the Transmission (TX) side of things.
Walk around with that phone on 40mW and even when you walk past an AP running at 25mW, you’ll end up connecting to the 200mW AP nearby. The phone is listening to the RSSI of the AP to work out which is closer. It doesn’t know you’re right under an AP, only that the 200mW AP appears like a better choice.
What if that AP is not a good choice – well you’re still connected to it and you’re not going to roam properly and drop out.
Let’s look at what happens if you apply power caps to your APs. Yes – you are indeed hobbling them. You are restricting what the AP can do, but it’s for a specific purpose. You’re balancing the AP transmit power to the client transmit power. You’ll rebalance that conversation to have two people talking at an even volume to each other. When this happens devices start to roam properly.
If you need some help working out roaming issues, or want some help to add more APs to your network to bring it up to voice level, email us as firstname.lastname@example.org