How do I decide where to place my AP in order to minimize interference?

We have an AP and I'm wondering if we can reduce interference by moving the AP to another place.

I know that other APs can interfere and I've set the router to use channels that are more free.
But are there other physical things I need to pay attention to? Does it matter how far the router is from a wall or other devices or are there other things that could cause interference?

Our microwave is 6 meters away and the AP stands close to a wall next to a monitor, a NAS and some power/USB cables behind a laptop.

The terms "access point placement" and "access point interference" didn't help me out well on Google... :-(

Tamara Wijsman

Posted 2011-05-04T00:00:12.073

Reputation: 54 163

There are way to many things you have no control over that could be causing interference (Neighbors)... I would say as long as you have a decent signal strength and no network issues you shouldn't worry about it. If you really want to know about your interference check out http://www.metageek.net/products/wi-spy/ :)

– Riguez – 2011-05-04T00:07:48.023

Answers

Higher positions for wireless routers tend to be more effective because there is often less potential for interference from furniture and other objects between your wireless devices. Keeping it away from other major electrical devices (such as microwave ovens and computer monitors {especially CRTs}) is a good practice that actually helps to minimize some interference.

As far as channel selection is concerned, I find that the vast majority of routers are set to "6" as the default, and that very few people actually bother to change this. To find out which channels are being used in your area you can use a program called Network Stumbler (which can also be very interesting to leave running on your laptop as you drive across the city):

Network Stumbler
http://www.netstumbler.com/

In addition to showing you which channels are in use (so that you can hopefully pick one that's not used at all -- start with the higher frequencies first since they seem to be very subtly better at not being effected by interference), it will also show you which routers have no security...

If you have to share a channel, you may be better off sharing a channel that doesn't have any unsecured wireless routers since those will potentially see more use (not only by neighbours, but also by occasional traveling criminals searching for unsecured wireless routers to use to do illegal things anonymously on the internet from their vehicles).

Randolf Richardson

Posted 2011-05-04T00:00:12.073

Reputation: 14 002

netstumbler may be good for some things, maybe it has a good refresh rate for channels.. (i'm not sure if ssider automatically sees when a router is set to a new channel).. but netstumbler isn't good for seeing what security is on wireless routers. it does get it wrong. i'm not sure if it'd detect WPA2 as such for example. SSIDer doesn't have that fault. – barlop – 2011-05-04T16:01:09.917

The last time I used Network Stumbler, it couldn't identify WPA2 specifically. It does, however, detect when there is no encryption. I keep hoping that the developers will update NetStumbler to differentiate right up to WPA2 (Windows XP with SP3 does this). – Randolf Richardson – 2011-05-05T06:02:27.433

@Randolf Richardson ok, well certainly use inSSIDer for seeing that. What are the advantages of netstumbler over inSSIDer? – barlop – 2011-05-05T07:59:28.470

@barlop: I'm not familiar with "inSSIDer" so I couldn't tell you. If it's free open-source software, then an evaluation shouldn't cost anything other than downloading and time to install and learn it. – Randolf Richardson – 2011-05-05T16:01:31.227

@Randolf Richardson I have tried it, that's why i'm telling you it's better than netstumbler for telling you the security on wireless networks. You don't seem to know that it is indeed free, yes really, free, no evaluation. I won't patronize you by telling you that since it's free, the only cost to you is time to learn it, so I would ask that you don't dare patronize anybody else by telling them that. And you should gratefully accept the very constructive recommendation of another piece of software that is better for a particular purpose than the one you use. – barlop – 2011-05-05T18:47:32.817

@barlop: You asked me what the advantages are, and I indicated that I didn't know. I certainly wasn't trying to patronize you -- I'm sorry that you viewed it that way. – Randolf Richardson – 2011-05-06T13:56:33.430

2 pieces of advice.

avoid placing your AP near to the microwave oven. Same frequency range.
use InSSIDer to fine tune your channel selection and placement.

Alain Pannetier

Posted 2011-05-04T00:00:12.073

Reputation: 722

I know InSSIDer, but how do I use it to determine that there is less interference happening? I would be moving the router closer/farther away from my laptop which would show up in my readings. Or is there a way to remedy that effect, by trying to keep the same distance or testing it further away like on another floor? – Tamara Wijsman – 2011-05-04T00:09:14.873

1if you keep laptop and AP at the same distance and move the pair back and forth in your accommodation you'll be able to see where the peak signa/gain optimal position is. Don't stay on the first graph tab (the one showing the channels): there is also a history tab IIRC. – Alain Pannetier – 2011-05-04T00:18:37.923