Your Wi-Fi router transmits your wireless signal in a preset channel that you configure using your router’s admin tool. The Wi-Fi channel is identified by a number ranging from 1 to 10 in the US or 1 to 13 in Europe. If you are living in area with crowded surrounding routers such as in an apartment complex, chances are your router’s performance is decreased as other routers are sharing the same wireless channel.
To optimise the wireless performance of your router, first scan the wireless signals around you, select the least crowded channel, and then change the channel of your WI-Fi router.
Fortunately, OS X Mountain Lion comes with a Wi-Fi scanner tool “Wi-Fi Diagnostics” that makes finding the best wireless channel around you less of a chore.
Wi-Fi Diagnostics is not readily accessible from the Launchpad or the Dock. To locate the app, open any Finder window, hit Command+Shift+G and enter the path “/System/Library/CoreServices/“. Search for “Wi-Fi Diagnostics” and double-click to launch the app. You might want to drag and drop the app icon into Launchpad or the Dock for easy access.
Ignore the pop-up Welcome window, instead select from menu File > Network Utilities or hit Command+N to launch the Network Utilities window.
Click on the “Wi-Fi Scan” tab. You will see a list of surrounding Wi-Fi network including your own with their name, channel, band, protocols, signal strength and noise level.
Look at the channel number being used by your neighbouring routers. If your wireless channel is being used by others, then select a number not being used or least used by others, and set it up as the channel number of your Wi-Fi router.