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FOURTH QUARTER 2010

   
Product Focus
Exploring the Connect802 value proposition...
Essential Wi-Fi
For those who are new to Wi-Fi networking...
Technology and Engineering
For the engineer and Wi-Fi network administrator...
To Infinity... and Beyond!
News from the wireless marketplace...

Product Focus

Elfiq Link Balancers

Link balancing and redundancy has often been difficult to implement, especially for small and medium businesses. Enterprise customers can handle the high price and complex configuration of load-balancing routers from vendors like Cisco, but what about a customer who doesn’t want to spend that much money, or who already has routing equipment and simply needs to add load balancing or redundancy?

Next Steps in 802.11 Development

Development of the 802.11 standard never slows down. You can tell how long someone has been an 802.11 engineer by which standard was “just around the corner” when he or she entered the industry. (If you know anybody who pre-dates 802.11b, they’ve been doing it a while!) For a long time, 802.11a and 802.11g were established standards, and 802.11n was “just around the corner.” Now that 802.11n has been ratified, what’s next? This issue, we’ll highlight 802.11ac and 802.11ad, two standards that you’ll be hearing more about in the future. (Don’t let the name fool you. 802.11ac and 802.11ad are not sub –standards of 802.11a. The IEEE simply ran through the entire alphabet—802.11a through 802.11z—and then started over at the beginning with 802.11aa, 802.11ab, 802.11ac, and so on.)

 Technology and Engineering

Recognizing and Troubleshooting Multipath Fading

Diagnosing Multipath

Signal from an access point’s antenna propagates in many directions. As it moves through the environment, it bounces off of obstructions, forming reflections. Multipath fading occurs when two or more reflections overlap in such a way that they cancel each other out. The specific locations in which multipath will occur are very difficult to predict, because multipath depends on very fine details in the environment, but the symptoms of multipath make it relatively easy to diagnose.

Multipath fading causes a dramatic, consistent drop in signal strength, that is highly localized to a relatively small area. The most important of these characteristics is that the fading is localized to a small area. With multipath fading, moving a few feet in any direction, or even a few inches in some cases, causes signal strength to return to normal. If the reduction in signal strength occurs over an area larger than a few feet, then multipath is not the most likely of causes.

Troubleshooting Multipath

Recognizing multipath is only the first step. Once you’ve diagnosed it, what can be done? Multipath is caused by the interaction between the signal and the environment, but changing the environment is not the ideal way of addressing it. Large, flat surfaces like walls are usually a factor, but moving them isn’t usually an option, nor is coating them with less-reflective material. Regardless, moving obstructions will simply move the fading-point, not eliminate it. Finally, the effect of moving obstructions will probably be unpredictable; you’ll know you’re moving the fading-point, but not where to.

The final, and potentially the best, way of dealing with multipath is to migrate to 802.11n. Through its technological wizardry, 802.11n turns multipath from a liability into an asset. Whereas with 802.11a, b, and g, multipath reduces or eliminates throughput, with 802.11n, the AP takes advantage of the multipath reflections to create multiple spatial streams. This means that the more multipath you have, the more throughput you can get. While this provides some hope for the future, currently there are still lots of devices out there that only support 802.11a, b, or g. Fortunately, 802.11n APs, with their two to four antennas, can still do good old-fashioned diversity if they need to, and better in some cases than an 802.11a, b, or g AP would!

Cloud-based WPA and WPA-2 Key-Cracking

Most of the stories we bring you in this section of the newsletter are exciting developments in the wireless industry. Depending on your perspective, this one may not be seen as good news. The web site http://wpacracker.com will attempt to crack your WPA or WPA-2 pre-shared key using their custom-dictionary and server farm. Pricing runs at $17 or $35 depending on how fast you want the attack run. All that’s required from you is a pcap trace file containing an authentication to the network.

Of course, none of this matters if users share the password amongst themselves or leave it stuck to the bulletin board, or anything like that. Ultimately, security is a multi-pronged fork, and the strength of your password may not be your weakest link.

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