Wi-Fi Friendly Cordless Phones

Question

Is there a practical solution (other than switching to a 5.8GHz phone or turning off the cordless phone) to eliminating interference between a 2.4GHz cordless phone and a wireless network?

- Bill

Answer

This question was answered on July 1, 2005. Much of the information contained herein may have changed since posting.

Wi-Fi or wireless networks are wildly popular in part due to the very low cost of the equipment.

The low cost of the equipment is due in part to the use of an unregulated and unlicensed radio frequency for making the connections.

This unregulated frequency (2.4GHz) is becoming congested with lots of consumer devices such as portable phones, wireless computing devices and even some microwave ovens that can cause debilitating interference for Wi-Fi networks.

Since the 2.4GHz spectrum is the most popular for cordless phones and wireless networks, not only do you have to worry about your own household’s use of each technology, your neighbor’s choices could also impact you (Especially if you live in an apartment or condo or have close proximity to many neighbors.)

Your cheapest option is probably to get a new cordless phone system but not necessarily a more expensive 5.8GHz system There are actually two kinds of 2.4GHz cordless phones available; one that is “wireless network friendly” and one that will wreak havoc.

The difference is in the transmission method of the cordless phones The most common (that will wreak havoc) uses a modulation process called FHSS (Frequency Hopping Spread Spectrum) while the wireless friendly units incorporate DSSS (Direct Sequence Spread Spectrum).

FHSS hops around “bull-in-a-china-shop” style with no regard for any other devices, searching for the best channel in the 2.4GHz spectrum to use while DSSS uses a more “polite” way of choosing the best channel

DSSS is specifically designed to co-exist with other devices (which is why Wi-Fi networks us it) and phones that incorporate it will have a manual channel selector switch which keeps it in a more confined area of the spectrum.

As for dealing with intrusions from a neighbor’s wireless network, you may want to change your broadcast channel.

By default, most Wi-Fi access points are set from the factory to use channel 6 which means it is right in the middle of the available spectrum.

If your neighbor decides to install a wireless network and leaves the access point set at channel 6 as well, it is competing with your access point for the same channel.

Try setting yours to either channel 1 or 11 so that you can be as far away as possible from the common channel 6 and then see if everyone is willing to turn off their “broadcast” so that your computer does not know that their access point exists and vice versa.

Windows XP is designed to constantly monitor the radio waves for a stronger Wi-Fi signal and this "wondering eye" can often cause disconnections as well.

In a previous column, I wrote about turning off the Windows Zero Configuration to eliminate the wondering eye problem, which is posted at our Free Help Center: DataDoctors.com/help (Search for WZC)

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Author

Posted by Ken of Data Doctors on July 1, 2005