Apple Mac OS X tips and tweaks
Improve your wi-fi network
If you have problems with your wireless internet connection, such as a poor transfer rate, intermittent access, dropped connections and so on, it may be caused by interference from another Wi-Fi access point. Wireless access points and routers with built in Wi-Fi networking can broadcast over quite long distances. Of course, walls, floors and other obstacles severely reduce the range, but even so, you may find that other people's wireless signals are all around you and they can interfere with your own Wi-Fi network.
A wireless network uses a specific frequency range to transmit on and to avoid problems of one device interfering with another they can use one of several different channels, numbered 1, 2, 3 and so on. The signals from two wireless access points or routers that use the same channel number will interfere with each other and any computers that connect to them will find that the connection is poor or even intermittent. By assigning different channels to the devices, such as 2 and 8 the degree of interference is greatly reduced and the computers that connect to the networks will be able to establish faster and more reliable connections.
The problem is that most people aren't wireless networking experts and they don't know that Wi-Fi devices can use different channels. They don't know what channels their devices are set to or how to change them. They just plug in the access point or router and that's it. But if your default channel is the same as your neighbour's then you'll both suffer. The solution is to discover which Wi-Fi channels are being used in your area and to choose one that is not being used by anyone else. You'll then have a great connection.
There are utilities that can scan for Wi-Fi networks and reveal all sorts of details about them, such as AirRadar. This handy tool lists the networks and the channels and in the screen shot you can see that three wi-fi-networks are sharing channel 11. This will only lead to poor connections for the people that use them and they should choose an alternative channel that isn't being used, like 7 or 8.
This screen shot was taken in a public place with several Wi-Fi access points and AirRadar is useful in this situation because it can tell you which ones are the best to use. An access point on its own channel will have less interference.
So how do you change the wi-fi channel? This is a configuration setting in the access point or router and since there are dozens of models that all use slightly different menus, you'll just have to figure it out yourself. Sorry.
A common way to configure one of these devices is to start a web browser and enter something like 192.168.1.1, which is its IP address. They contain a mini web server and you'll see a log-in page that prompts for a username and password. Look in the device's manual or on the manufacturer's website for the default username and password if you don't know them.
Once you get past the log-in page there will be menus, links and buttons to change the configuration settings. Look for the wireless configuration options and change the channel number. You'll need to save the settings and restart the device for it to take effect. You don't need to do anything on your Mac because it will discover the new setting just like any new Wi-Fi network.
An alternative is WiFi Scanner, which is in the Mac App Store. Again it costs $19.99, but it's pretty good. A third utility for displaying Wi-Fi network information is KisMAC, which is a free, open source wireless stumbling and security tool. It works fine and is well worth trying. Also free is iStumbler, but it seems to quit unexpectedly with OS X Lion. It should be fine with Snow Leopard though.