Don’t talk to me while I’m in the shower.
What has that got to do with wireless? Bucketsful. After two years of being told time and again by various members of the Bluetooth consortium that collisions between Bluetooth (the local wireless peer-to-peer technology) and 802.11b (wireless Ethernet) transmissions are negligible – despite the fact that they share the same 2.4GHz frequency band – this week somebody told me something different. And what I’ve just heard makes more sense.
If a single 802.11b access point is more than 20 metres from the wLAN (wireless LAN) card and Bluetooth is active, the 802.11b signal will die. If you are sitting in one of four cubicles with an active Bluetooth device, the access point must be within 10 metres or the signal will die, and so on.
Remember, Bluetooth is always active. As long as the device is integrated into a notebook, cell phone or PDA that is on, it is always polling for a similar technology.
Not a serious problem, you say? I am told Ford Motor Co. has banned Bluetooth from its Dearborn, Mich., campus because Ford also uses 802.11b.
“Don’t talk to me in the shower” is the analogy used to explain the problem.
If you’re taking a shower and someone tries to talk to you from the next room, the drops of water close to your ears block out the sound waves. The farther away the speaker, the weaker the signal, until you don’t hear it at all. The closer the speaker comes to the shower, the more likely you are to hear him or her.
The speaker is the 802.11b access point, you are the wLAN, and Bluetooth is the water pounding down around your ears and drowning out the signal.
The source of my latest research? Mobilian Corp. (www.mobilian.com), a company that calls itself a multistandards radio company.
Mobilian does have a vested interest in this news. After all, it has 20 patents pending on interference-mitigation techniques that will allow both radio systems to be incorporated in a single device or to be used in the same area.
But it is not selling its solution to consumers. Mobilian will sell it to system OEMs such as Toshiba, Dell and Compaq and to the makers of 802.11b access points such as Lucent, Nortel, 3Com and others. All these companies have engineers who are in a good position to know whether or not Mobilian speaks the truth.
If Mobilian is right, these companies will have one of three interesting choices:
Choice No. 1. Decide that the status quo isn’t so bad. They might ask, “Why go to the extra expense of buying additional technology?” They can weather the complaints from the few consumers or companies that have problems, right?
Choice No. 2. Decide there is a problem and integrate either Mobilian’s solution or a similar solution into their products.
Choice No. 3. Offer some devices at one price without a solution that mitigates the interference and then offer at a higher price a luxury version that works all the time.
Does this have the potential to turn into a real problem for providers and customers?
Scenario No. 1. MobileStar Network Corp. just signed a deal with Starbucks Corp. and Microsoft Corp. to put wLAN access points in all 2,200 Starbucks coffee shops. The access points connect to servers connected to the Internet. A year down the road you might find yourself in Starbucks with your new company-issued Toshiba with wLAN and Bluetooth built in. So what’s the problem?
“Bluetooth will kill the signal,” says Ron Nevo, director of engineering at Hillsboro, Ore.-based Mobilian.
Scenario No. 2. Wayport is doing the same thing as MobileStar but at airports.
Yes, 802.11a, the next version of wireless Ethernet, will move to the 5GHz band, but in the meantime, Intersil is currently shipping about 1 million 802.11b chips each month. I think 802.11b will be around for a while.
Remember that the higher the frequency – in this case 5GHz – the more problems it has going through walls and people.
Ephraim Schwartz is an editor at large in InfoWorld’s news department.
