Wi-Fi Advice: Wi-Fi Boosters, Hotel Wi-Fi: Page 2

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Q: I had a nagging problem with my son's MacBook dropping wireless with a "security compromised" message. Turns out, my wife's laptop (XP) was corrupting the network with VPN. As soon as I switched to AES versus TKIP the problem disappeared. Not sure if Macs don't do TKIP well, or XP doesn't... but AES is quite stable. – Al

A: Perhaps we ganged up on Microsoft error messages too soon. A good number of Mac users have reported frustration and confusion with the infamous "Your wireless network has been compromised" error. What's worse, in fact, than Microsoft's empty rhetoric is that this message actually causes OSX to disable your wireless network for one minute. Gee, thanks Apple!

Of course, OS X thinks it is doing you a favor. After all, it has decided that your wireless network is being hacked by a nasty intruder, and so taking your machine offline is for your own good. The only problem is, chances are, that there is no intruder.

Little seems to be known about the exact cause of this error, and Apple has yet to address it despite reports dating back to at least 2004. Some users are affected frequently—as in repeatedly, every day—while others have never seen this error. Based both on my personal experience with this error and other user reports, it appears that the trigger involves the presence of a PC-based wireless client using WPA-TKIP.

For example, at a friend's house I had setup a wireless network using WPA-TKIP, and configured both her MacBook and my PC to the appropriate settings. The MacBook would connect to the network, but as soon as my PC would connect, the Mac would throw the security error and shut down her connection.

As Al discovered himself, changing all parties involved—the router and the clients—to WPA-AES encryption solved the problem and everyone got along happily.

The question remains, though, is TKIP encryption tickling a bug in OS X? Have you seen this error on a Mac and found any other solution and/or explanation? Considering how widely used TKIP is (as the default WPA encryption scheme in most wireless routers), it seems odd that this bug would persist in OS X for so many years. If you have insight to share, click on my byline above to send us your feedback, or use the Comments tool below.

Q: I am grappling with the concept of the Wi-Fi booster. For example the Hawking HSB2 is an RF signal amplification device with many fans boasting magical improvements--but how? It's surely easy enough to boost output power and thus be seen as a stronger signal from farther away. But the device comes with a paltry 2dbi antenna, leaving us all with the cosmic mystery of how the return signal becomes suddenly adequate. I suppose that the receiver within the booster could be extra adept at rooting around in the tall grass to extract signal, but if there is that much SNR left over, why aren't the "quality" component manufacturers exploiting it already? – Ron

A: Although my expertise in RF is limited, I am inclined to agree with the sentiment in Ron's first paragraph. These so-called "Wi-Fi boosters" are basically amplifiers that make the transmitted signal "louder" (if you think about it in radio terms). But unlike a radio, the client is not a passive receiver—it, too, sends signal back to the wireless transmitter. The client is limited by the power output of its own transmissions. In other words, the Wi-Fi booster may let your client "hear" the wireless router from a further distance than it would otherwise, but the client itself might not be strong enough to send anything back—leaving you in the same boat as if you couldn't see the wireless network at all. Or more specifically, dangling an SSID that you can see, but not associate with.

Also remember that when you amplify signal you also amplify noise. Many users have reported that, when cranked to max output, these Wi-Fi boosters can actually hinder performance of nearby clients, whose own receivers essentially "drown" in the noise. To minimize this problem, one may need to compromise by setting the Wi-Fi booster to a mid-range power level—say, 100 to 200 milliwatts. Of course, this will also reduce its maximum range, and so what's the point?

The point, according to those who have evaluated these boosters, is to better fill in your existing wireless range. In other words, if you expect the booster to give you a strong signal much further away than you could before, this may not pan out. But, if you would like to give a boost within the range you already experience—and maybe catch some of the "dark corners" that are otherwise too weak—a signal booster set to a mid-range power output could very well do the trick.

An entirely different way of using a Wi-Fi booster would be for creating a long-range fixed wireless link. In this case, you don't care so much about clients near the receiver, so you can pump up the power output. Plus, you would want to use a pair of boosters, one at each end of the link, so you don't wind up with the asymmetrical power problem described above. Finally, you would also want to replace the "paltry" 2dbi antenna with a more powerful directional antenna. You'll always get the longest range using directional antennas precisely aimed at one another, but of course this will not provide much or any signal outside their straight-line path.

Article courtesy of Wi-Fi Planet.





Tags: Windows, Microsoft, wireless, Mac, WiFi


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