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Stimpy
Newbie (2 Posts)
4/26/2006 9:50:52 AM
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Pardon me for just explaining why theres a problem and offering no solution.
Preferred solution #1. Use a 900mhz phone, this is optimal for a lot of reasons.
1. Better range then 2.4 or 5.8 phones, has to do with the physics of wavelength vs. power.
2. Doesn't compete with either 2.4 or 5.8 phones or Wifi (b/g and A)
3. typically cheaper
QUOTE:
Originally Posted by Stimpy:
The problem is in the way that 802.11b/g operates and the way that many cordless phones operate.
Wifi (802.11b) is a direct sequence spread spectrum technology, that is in the 2.4 - 2.483 ghz spectrum, Wifi uses channels that are 22 mhz wide, at each channel center point Wifi hops 11 mhz down, and 11mhz up from the center of the channel, 400 times per second.
the "unlicensed" bands, such as 900mhz, 2.4ghz, 5.8ghz are just that, unlicensed, meaning that anyone can develop any technology they want to utilize the spectrum. The FCC regulates this simply by putting parameters on the EIRP (Equivalent Isotropically Radiated Power) emitted at the antenna, in 2.4ghz, not to exceed 4 watts. the presumption being that this would curtail people stomping on each other to some degree.
Most modern cordless phones use Frequency Hopping Spread Spectrum, and typically do it across the entire available spectrum. BlueTooth is also a FHSS technology. While cordless phones are typically proprietary in their use of FHSS as far has hop sequences and how many times per second they change frequencies, it can be similar to BlueTooth which hops at 1600 times per second across the entire 2.4ghz range.
What does all this mean?
In order for your Wifi device to communicate it must be able to distinguish data signals from background noise (such as microwaves, cordless phones, bluetooth). The higher the "noise floor" the more signal strength you need between your wireless access point / router and your client device. When the difference between noise floor and received signal strength is not sufficient the data packet won't be seen.
Additionally, and more common, since these FHSS devices are typically hopping thru the entire sprectrum at a must faster rate then your wifi, they have a much greater chance of sending signal on the exact same frequency at the exact same time as your wireless, each signal currupting the other and causing the devices to use whatever mechanism has been designed to deal with such issues.
For Wifi, every packet sent by either side of the communication is to be acknowledged by the receiver. If no acknowledgement is received, then the sender "resends" the data packet. Potentially dramatically reducing performance.
Even phones that market them as 10 channel phones, don't really behave well in these environments, because they are typically constantly searching, probing the available channels for the "least congested" place to do business.
QUOTE:
Originally Posted by Ricker:
QUOTE:
Originally Posted by tbs205:
I have just installed a Linksys wireless router model WRT546 and it is using the frequency as our cordless phones already in use. 2.4 ghz. Everytime the phone is in use it diconnects me from my router. I can't believe with push on the cordless phones that are 2.4ghz that someone else hasn't had this problem. It doesn't appear that the phones have any type of channel selection other than when your already talking.
Is there a fix to this.
Thanks
Hi.. yes, there is a fix... I cut to a 5.8 Ghz wireless phone. Now I am happy and connections
drop whjen I want them to.... No surprises...
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