How To Buy a Wireless Router: 2014 Edition

[bobm_10]

Hi:

"The 2.4 GHz band has 11 channels (in the U.S.), each of which is 20 MHz wide. If you do the math (or look at Figure1) you'll see that only three of them (Channels 1, 6 and 11) don't overlap. Channel overlap is bad, because it's another form of interference, which reduces your wireless LAN's speed and reliability."

Thanks for the article although I was confused on a few points. Considering the importance of using channel 1, 6, or 11:

1) I understand these channels don't overlap each other, but channel 1 will overlap with 2? So if I had a neighbor using channel 2 and I was on channel 1, I would still have a problem? So I am not sure how any one channel is better that the other?

2) I checked my router and noticed I could either select a channel or leave it on the default of Auto. In this case what does auto mean?

Thanks Bob

 

[CaptainSTX]

Auto means the router picks a channel which it "thinks" is best.

There is no documentation available for most routers explaining how it makes the decision or how often if ever it reconsiders what channel to be on.

What is known is that some wireless devices get confused and lose their connection when the router changes channels.

 

[thiggins]

Using channels 1, 6 and 11 yields three non-overlapping channels, the most you can get in 2.4 GHz.

The reason you don't want to use overlapping channels is that signals from overlapping channels look like noise. The more noise, the lower your performance.

CaptainSTX answered the auto question.

 

[stevech]

In countries allowing the higher ISM band upper band-edge, higher than permitted by the US FCC, one can fit 4 non-overlapping 802.11n channels, as the occupied bandwidth is about 18 MHz, rather than 20MHz. Of course, 802.11n can drop down to 802.11g modulation modes and thus widen to 20MHz.

 

[bobm_10]

Using channels 1, 6 and 11 yields three non-overlapping channels, the most you can get in 2.4 GHz.

The reason you don't want to use overlapping channels is that signals from overlapping channels look like noise. The more noise, the lower your performance.

Interesting, but if you only have 1 Wireless router in your home (excluding neighbors in this example) any of the 11 channels would be as good as another? -Bob

 

[sfx2000]

Hi:

"The 2.4 GHz band has 11 channels (in the U.S.), each of which is 20 MHz wide. If you do the math (or look at Figure1) you'll see that only three of them (Channels 1, 6 and 11) don't overlap. Channel overlap is bad, because it's another form of interference, which reduces your wireless LAN's speed and reliability."

Thanks for the article although I was confused on a few points. Considering the importance of using channel 1, 6, or 11:

1) I understand these channels don't overlap each other, but channel 1 will overlap with 2? So if I had a neighbor using channel 2 and I was on channel 1, I would still have a problem? So I am not sure how any one channel is better that the other?

2) I checked my router and noticed I could either select a channel or leave it on the default of Auto. In this case what does auto mean?

Thanks Bob

Hi Bob - 802.11 in 2.4GHz space has up to 14 channels - here in the North American markets (US/Canada/Mexico), channels 1 thru 11 are available.

These channels do overlap, e.g. 1 will overlap with 2,3,4, and parts of 5. So realistically for most folks, it really comes down to three practical choices - those being 1, 6, and 11

 

[sfx2000]

Auto means the router picks a channel which it "thinks" is best.

There is no documentation available for most routers explaining how it makes the decision or how often if ever it reconsiders what channel to be on.

What is known is that some wireless devices get confused and lose their connection when the router changes channels.

Auto is interesting, as there is not "standards" guidance, so much of this is implementation - some are better than others - and some do this on a periodic basis, and some only do the autoscan on boot time...

As for AP's changing channels - for the most part, shouldn't be an issue, unless the client SW is very poorly written - the AP is in charge, and if it switches channels, most clients will notice the loss and scan/reattach...

 

[bobm_10]

These channels do overlap, e.g. 1 will overlap with 2,3,4, and parts of 5. So realistically for most folks, it really comes down to three practical choices - those being 1, 6, and 11

I must be missing something. I am thinking what we need to say is; 1, 6 and 11 are good choices if you need to place "three" Wi-Fi routers in close proximity. That way you will avoid overlap/noise. If you only have one Wi-Fi router, take your pick of any of the 11 (US based) channels. Does that make sense?

thanks, Bob

 

[stevech]

If you are rural, any channel. Urban, not so.

 

[thiggins]

I must be missing something. I am thinking what we need to say is; 1, 6 and 11 are good choices if you need to place "three" Wi-Fi routers in close proximity. That way you will avoid overlap/noise. If you only have one Wi-Fi router, take your pick of any of the 11 (US based) channels. Does that make sense?

Airwaves are shared by devices that are in range of each other.

If there are no other networks in range, then choose whatever channel you want. Your router isn't going to bother anyone and there are no other networks to interfere with yours.

If you can see other networks, then they can affect the performance of your network and vice versa. So you want to choose your channel to minimize interference to and from your network in order to maximize performance.

See http://www.smallnetbuilder.com/wire...x-your-wireless-network-part-2-site-surveying

 

[sfx2000]

I must be missing something. I am thinking what we need to say is; 1, 6 and 11 are good choices if you need to place "three" Wi-Fi routers in close proximity. That way you will avoid overlap/noise. If you only have one Wi-Fi router, take your pick of any of the 11 (US based) channels. Does that make sense?

thanks, Bob

Hi Bob,

You pretty much nailed it... but even with a single router, take a site survey and see what's out there - and then pick the channel that works best.

1,6,11 - normally in a crowded neighbourhood - these are safe bets, and it's good to be in the habit here.

The channel numbers were allocated long before 802.11b went to 20MHz, and caused the overlap issue in the first place - 5Ghz channel assignments are much easier to work with.

sfx

 

[azazel1024]

Right to pretty much all above. A clarification, channels are actually only 5MHz wide in 2.4GHz. So channel 1 is 5MHz, channel 2 is 5MHz, etc. However, 11g uses effectively 20MHz and 11n 18MHz, which is why it covers multiple channels when you are selecting just one channel.

On 5GHz it makes more sense as the channels are indicative of 20MHz width (though if you notice, the channel numbering still follows 5MHz per channel. As the selections are, as an example, channel 36, 40, 44, 48, etc. You just don't have the choice of "between" channel selections like you do on 2.4GHz).

In an area where you can detect no other 2.4GHz networks, then playing with channel selection for best performance is the way to go. If you can detect other channels (unless EXTREMELY weak) then you pretty much only want to pick one of the three "prime" channels to reduce the chance of interference, 1, 6 or 11.

Odds are, considering the tiny frequency spread, that performance on channel 1 is going to much the same as on channel 2 or 3 or 4, etc. On 5GHz this is somewhat a different matter both between broadcast power restrictions on parts of the 5GHz band, but also the frequency spread is MUCH greater than on 2.4GHz. 2.4GHz you are talking ~60MHz of spectrum it covers, so propogation at 2.42GHz is going to much as it is at 2.48GHz for example. On 5GHz band though, you've got roughly 5.2GHz up to 5.9GHz in which you are operating, broadcast power limits aside, there could be a resonable different in propogation for a signal at 5.2GHz than there is at 5.9GHz (either absorbtion, reflection, etc).

 

[bobm_10]

In an area where you can detect no other 2.4GHz networks, then playing with channel selection for best performance is the way to go.

My house is rural so I have been using an inexpensive Netgear N-150. It's set to auto but always seems to be on channel 6. I have never had a problem, great range, no reboots and two concurrent users can stream Netflix. I am not going to replace until I find a reason. Note, I actually use two N-150, one just as a router (basement, wireless off) and the other as an access point on my second floor.

Thanks all for the help,

Bob