Recheck WiFi Channels Every Year
Every year or so, it is a good idea to check the WiFi networks around your home to see if your neighbors have decided to setup their WiFi on top of yours. Often, these wizard setups just pick a channel and use it without any regard for how many other access points are already on that channel or whether a channel overlaps others in use. In any WiFi location, having more than 1 access point on a channel - or even the nearby channels of the radio spectrum will reduce your bandwidth and will probably lead to dropped connections.
In the USA, there are 11 channels for 802.11b and 802.11g wireless networks to use. However, only 3 of those channels do not overlap, 1, 6, and 11. That means choosing any channel besides one of those three is to be avoided. In my neighborhood of single family homes with USA average sized lawns, I see 9 WiFi networks from my home office, one of them is mine. Here is a table created by a wireless router Wireless Site Survey function:
From where I sit, 4 people should change their WiFi channels from 10-11 to something else - anything else. Obviously, they will see different signal strengths from their locations, but using channel 10 isn't very bright. The guy on channel 1 is very happy, since he's all alone!
So, I need to pick a channel that has the least amount of interference from my neighbors and is one of 1, 6, or 11. The SSID that begins with a 'j' is mine. Just looking at the quality column, the 2 closest signals are on channel 1 and 11. The next highest quality signals are on ch 10, 10, and 11 - so the choice is clear. I need to choose channel 6. BTW, I was on channel 11 yesterday. It had been a few years since I'd looked at my wifi neighborhood. I'm glad I looked again.
Apartments
If you are in a very dense living situation like a dorm or apartment, then you may need to choose one of the other channels. This is where really looking at the frequencies and understanding that RF is a 1/r^^2 law helps with your selection.
Directional Antennas
If you live in a corner apartment, then you have another option - use a directional antenna to increase the gain in your apartment away from your neighbors. A quick google will help you find a parabolic template (PDF file) that can be used to build an aluminum foil parabolic antenna helper with about 12 dB of gain increase. That can be the difference between marginal and good WiFi. I've never needed this, but a friend spent 8 minutes building his first and 3 minutes building the 2nd with card stock paper, aluminum foil and some glue.
In the USA, there are 11 channels for 802.11b and 802.11g wireless networks to use. However, only 3 of those channels do not overlap, 1, 6, and 11. That means choosing any channel besides one of those three is to be avoided. In my neighborhood of single family homes with USA average sized lawns, I see 9 WiFi networks from my home office, one of them is mine. Here is a table created by a wireless router Wireless Site Survey function:
| SSID | BSSID | RSSI | Noise | Quality | Ch | Rates | |
| NETGEAR | 00:1F:xx:xx:xx:xx | 0 | 11 | 1,2,5.5,11 | |||
| 6,9,12,18,24,36,48,54 | |||||||
| GO********* | 00:1C:xx:xx:xx:xx | -79 dBm | -93 dBm | 14 | 11 | 1,2,5.5,11 | |
| 6,9,12,18,24,36,48,54 | |||||||
| ***** | 94:44:xx:xx:xx:xx | -72 dBm | -93 dBm | 21 | 11 | 1,2,5.5,6,11,12,24 | |
| 9,18,36,48,54 | |||||||
| ******* | 00:13:xx:xx:xx:xx | -71 dBm | -93 dBm | 22 | 1 | 1,2,5.5,6,11,12,24 | |
| 9,18,36,48,54 | |||||||
| j********** | 00:16:xx:xx:xx:xx | -41 dBm | -95 dBm | 54 | 6 | 1,2,5.5,6,11,12,24 | |
| 9,18,36,48,54 | |||||||
| ************ | 00:1E:xx:xx:xx:xx | -92 dBm | -95 dBm | 3 | 6 | 1,2,5.5,11 | |
| 6,9,12,18,24,36,48,54 | |||||||
| 2WIRE*** | 00:21:xx:xx:xx:xx | -85 dBm | -95 dBm | 10 | 10 | 1,2,5.5,11 | |
| 6,9,12,18,24,36,48,54 | |||||||
| 2WIRE*** | 00:26:xx:xx:xx:xx | -79 dBm | -93 dBm | 14 | 10 | 1,2,5.5,11 | |
| 6,9,12,18,24,36,48,54 | |||||||
| ******* | 00:26:xx:xx:xx:xx | -92 dBm | -95 dBm | 3 | 6 | 1,2,5.5,6,11,12,24 | |
| 9,18,36,48,54 |
Channel Count 11 3 10 2 6 3 1 1
From where I sit, 4 people should change their WiFi channels from 10-11 to something else - anything else. Obviously, they will see different signal strengths from their locations, but using channel 10 isn't very bright. The guy on channel 1 is very happy, since he's all alone!
So, I need to pick a channel that has the least amount of interference from my neighbors and is one of 1, 6, or 11. The SSID that begins with a 'j' is mine. Just looking at the quality column, the 2 closest signals are on channel 1 and 11. The next highest quality signals are on ch 10, 10, and 11 - so the choice is clear. I need to choose channel 6. BTW, I was on channel 11 yesterday. It had been a few years since I'd looked at my wifi neighborhood. I'm glad I looked again.
Apartments
If you are in a very dense living situation like a dorm or apartment, then you may need to choose one of the other channels. This is where really looking at the frequencies and understanding that RF is a 1/r^^2 law helps with your selection.
Directional Antennas
If you live in a corner apartment, then you have another option - use a directional antenna to increase the gain in your apartment away from your neighbors. A quick google will help you find a parabolic template (PDF file) that can be used to build an aluminum foil parabolic antenna helper with about 12 dB of gain increase. That can be the difference between marginal and good WiFi. I've never needed this, but a friend spent 8 minutes building his first and 3 minutes building the 2nd with card stock paper, aluminum foil and some glue.
Background
I've been using WiFi at the house for about a decade and have deployed multiple WiFi networks over the years with B, A, G, and now N. I've authored a fairly popular WiFi Security Checklist and designed WiFi deployments for corporations with over 1200 locations. BTW, at those corporate locations, when they use WiFi, they also use an IPSec VPN. No WiFi technology should be considered secure enough for corporate use.Trackbacks
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