Cordless Phones & Wifi

[Kelvin]

Whenever someone uses our cordless phone, I would have to restart the router and my computer to get the wireless connection working again. Turning on Interference Robustness solved the problem but significantly reduced my range by about 30%. What does this option do and why does range take a hit?

TIA guys

[penmanila]

cordless phones and wi-fi operate on the same 2.4 ghz frquency. according to wi-fi planet:

Interference from Cordless Phones
By Jim Geier


More and more households and businesses today are using cordless phones, made by a variety of companies, including Panasonic, Siemens, and Sony. The cordless phones supposedly sound clearer and have much better range than wired phones. Of course they also provide mobility.

Cordless phones operate on 3 different frequencies, 900MHz, 2.4GHz, and 5GHz. Do those last two frequencies sound familiar? Yep, at least the 2.4GHz and 5GHz frequencies fall in the same frequency bands as 802.11b and 802.11a wireless LANs, respectively -- and the use of the phones can cause significant RF interference to your WLAN.

Potential 802.11b Interference

The majority of cordless phones in use today are 2.4GHz models. These phones, innocent as they may seem, reap devastating effects on 802.11b WLANs. Finding cases where 2.4GHz phones severely interfere with 802.11b WLANs is usually an easy task. Some 802.11b WLANs have even been totally shut down by somebody simply answering a 2.4GHz cordless phone. Why? The answer lies in the technology.

Most 2.4GHz phones use frequency hopping spread spectrum (FHSS) technology that operates within the 2.4GHz spectrum. FHSS hops from frequency-to-frequency across the entire 2.4GHz spectrum. 802.11b WLANs, on the other hand, use direct sequence spread spectrum (DSSS), which transmits within approximately one third of the 2.4 GHz spectrum. Because FHSS jumps across the entire spectrum while DSSS stays in only one portion, a FHSS 2.4GHz will clobber an 802.11b network, causing interference or even failure.

[ginoledesma]

If your router supports it, try changing the channel its operating on. I found out that when operating on Channel 11, I would get severely poor performance, but when I changed it to Channel 5 (on a whim), it worked as expected.

Some cordless phones operate at the 2.4GHz range, but most of the ones sold here operate only at 900MHz. Still, its a good thing to try switching channels first. Also, try downloading the Apple Airport Management Tools to see how well your signal-to-noise ratio is.

[Kelvin]

Hi Gino! I have an MSI Wifi Router so I don't think I can use that program. Anyways, I've just upgraded the routers firmware, hopefully this will solve some of the problems I've been having.

[ginoledesma]

The Aiport Management Tool comes with an app that can show you your Airport card's performance (bandwidth and signal-to-noise ratio). It isn't exclusive to the Airport Base Station, although it does come with a tool to manage all ABS/AEBS in range.

[johnj2803]

sorry have to revive this thread... the question what is Interference Robustness has not been answered yet

i am curious as well... whe do we turn this option on?

[berrybianka]

Does this affect the internet connection or just the range? Does the cordless phones only affect the router only when being used or the fact that it's around affects it already? Have a 5ghz cordless phone 6 meters away from the router.

[ricocamus]

Some cordless phones operate at the 2.4GHz range, but most of the ones sold here operate only at 900MHz. Still, its a good thing to try switching channels first.

The legally allowed frequencies for cordless phones in the Philippines are in the 46 MHz to 49 MHz band and another narrow range of 1.88 to 1.92 GHz. Cordless Phones that are in the 900 MHz can get interference from and can cause interference with regular mobile phones that also operate in that range. Cordless phones that use the 2.4 GHz range can cause interference with Wi fi and the newer 3G phones that also operate in that range.

Interference can affect Wi fi in many strange ways, since if you are one the same frequency you will be transmitting information that the wifi router won't know what to do with. You could also be transmitting at higher power outputs than what the wi fi routers or transceivers in the laptops are expecting, causing even more problems.

Since most phones and most wifi routers and most wifi transceivers in computers have a way of switching channels, you can experiment with the different channels to see which ones work. IMHO the easiest would be is to change the frequency channel on the phone.

[LeoCastillo]

Hey gang!

I ordered a 5.8GHz cordless system from Amazon, specifically because it doesn't reach my 802.11g wi-fi system. I just realized that no one is selling this frequency in the Philippines. May tatamaan ba akong current bandwidth where I'll get interference? (just like 900mhz will hit the cell phones).

Leo

[Linus]

Hmm! This might be reason for those linksys routers dying suddenly before. I wonder if there's a correlation.