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  • CWNP

Understanding OFDM- Part 4

In the previous episode of “Understanding OFDM”, we discussed the effects that convolutional coding error correction has on our overall channel data rates. The reason for using an error correction mechanism is to attempt to recover signaling information which has been corrupted by RF noise or interference during its transmission. But what exactly is this RF noise and how does it corrupt our OFDM-based 802.11 transmissions in the first place? Continue reading...

  • CWNP

On Classroom Education

I had a bit of a work vacation two weeks ago.  I spent the week auditing a CWSP class with David Coleman (author of the CWNA study guide).  Unfortunately, taking a week to do something like this doesn’t mean that my other responsibilities magically disappear, so it made for a busy week and a long commute through the bottomless traffic pit that is Hotlanta.  No less, it was a great experience just sitting in the back, observing and participating in the structured and systematic 802.11 security education.

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  • CWNP

Vendors are Getting Saasy

Aruba started a competition that is beginning to get interesting.  Aerohive started a different competition that seems to be catching wind.  What am I talking about and who are the competitors?  Well, Aruba got down and dirty on AP price, so Aerohive got down and dirty on AP price.  Aerohive introduced a hosted WLAN management solution, so Aruba did the same.  Motorola (with Brocade) announced intentions of following suit, but we all know that big partnerships between big companies with big plans take big time.  I’ll leave it to you to decide who is leading the race, but here are the facts. 

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  • CWNP

Understanding OFDM - Part 3

In Part 2 of this series, we determined the maximum baud rate for 802.11a/g, and calculated the maximum channel data rates by modulation type.  As an example, if using a BPSK modulation type  we arrive at raw channel data rate of 12 Mbps, for an 802.11a/g channel.  As a wireless LAN professional, you may be aware that the lowest data rate offered, in a pure OFDM 802.11a/g network, is 6 Mbps.  In order to understand the difference between the raw channel rate and the actual available channel rate, we need to see the effect that the forward error correction (FEC) mechanism used with 802.11 OFDM technologies, has on the transmitted information stream.

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  • CWNP

Wireless LAN Security and IEEE 802.11w

As Wireless LANs (WLANs) have been increasingly entrusted to carry mission critical enterprise data and voice communication, the impact of Wireless LAN (WLAN) Denial of Service (DoS) attacks has increased manyfold. The recently ratified 802.11w standard that provides Management Frame Protection (MFP) does provide some help in fighting WLAN DoS attacks. But, if you think that 802.11w can put an end to all of your WLAN DoS problems, I beg to differ. Please read on to find out why.

 

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  • CWNP

Pimpin [Wi-Fi] Ain't Easy

CWNP is on the road again, this time we’re mixing it up with Ruckus Wireless.  We’re out to save the world—several major US cities, at least—of boredom by offering some free Wi-Fi training, cool product demos, free food, handouts, and some wicked prize drawings.  If you don’t already know their corporate personality, Ruckus Wireless has what might be labeled “artistic moxie” when it comes to marketing and corporate culture.  They’re the antithesis of the stuffy, conventional, humorless corporation, which is just one of the reasons why they continue to succeed in Wi-Fi… it’s also why our roadshow is titled “Pimp My Wi-Fi.” 

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  • CWNP

Beam Me Up

On September 11, there was a flurry of excitement about the final ratification of the 802.11n amendment.  We were all glad that the seven years' war was over.  It seemed like the industry was excited to see this completion, but the crickets chirped after the first day or two of headlines.  Within the first few weeks, there have been some important developments, and the next few months should be exciting as well.  Here are a few pseudo-random thoughts on how Wi-Fi will change in the aftermath of the 802.11n-Draft era. 

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  • CWNP

Understanding OFDM - Part 2

In Part 1 of this “blogtorial”, Rick provides a high level comparison of the way OFDM is used in IEEE 802.11a/g.  In Part 2, he gives a more detailed description of OFDM subcarriers and the four modulation types used in Wi-Fi. Continue reading...

  • CWNP

Understanding OFDM - Part 2

<p>In Part 1 of this “blogtorial”, Rick provides a high level comparison of the way OFDM is used in IEEE 802.11a/g.  In Part 2, he gives a more detailed description of OFDM subcarriers and the four modulation types used in Wi-Fi.</p>   Continue reading...

  • CWNP

Understanding OFDM - Part 1

The 48-string Guitar

Like the sidewalk under your feet, always solid, never doubted, Orthogonal Frequency Division Multiplexing (OFDM) is the rock that supports current and near-term wireless technologies, including 802.11a, 802.11g, 802.11n, WiMAX, and LTE. As a wireless professional, you’ll be working with OFDM-based technologies for the foreseeable future. An understanding of OFDM will give you an edge in designing and maintaining the networks under your care.

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