Can you really plug RF leaks?

Last week Meru (May-Roo) Networks unveiled their "RF Barrier" product that promises to jam (interfere with) your corporate Wi-Fi signals outside the four walls (if you have four walls) of your building and into outside areas where evildoers lurk to highjack signals.

You've got to give Meru credit. This is a common gripe of enterprise networkers: "why can't you make it so Wi-Fi signals stop where I want them to?" And Meru is at least trying to address this problem in a creative way.

But the problem is that Wi-Fi signals bounce around and a simple 180 degree antenna is no match.  If you compared this to turning on a radio, where the noise is everywhere, the only way to really control the broadcast is to put a big tube over the speaker so the sound is confined. That's essentially what we do with Wi-Fi.

Meru's suggestion is to effectively scramble internal corporate Wi-Fi signals by mounting APs outside the building (broadcasting in 180 degrees which is next to impossible), thereby creating interference for the would be hacker trying to steal the internal signals. 

But most Wi-Fi signal patterns have side lobes and back lobes which tend to project the interfering signal into the internal space where you don't want it. This means that the signals, by definition, will self interfere,to a great extent, with the rest of the system.

Meru's approach (in addition to attacking the 802.11 fair access procedures) purposely creates unwanted and nasty interference, violating the general intent of the 802.11 protocol. This ‘bad, bad neighbor’ behavior would certainly be viewed as very problematic from the Wi-Fi Alliance’s point of view. What if you happened to run your business network on the other end of the unfortunate parking lot of a Meru barrier system?  Instead of defending, Meru decided to offend.  Not good, unless you have Ruckus smart antennas working for you. 

In case you don’t have neighbors or don’t care about offending them, Meru’s jamming (interfering signals) will actually radiate in almost all directions with 0dBi or above antenna gain.  A 180 degree antenna transmits a sizable amount of energy in 330 out of 360 degrees. This approach creates tons of radio fog interference for ALL users including on those on the inside of your business causing lots of unnecessary retransmissions and throughput degradation.

If you're up for it, here's an antenna pattern (click on the image to your right) for a commercially available 180 degree antenna that shows radiating signal power as a function of angle (strap yourself in). 

This is a plot of antenna gain vs angle (e.g. at 180 degrees from the boresight, the gain is about 4 dBi). So if an antenna is pointed outward from a building, the power shooting backwards into the building is still higher than it would be with a 2 dBi omni.

So what does Ruckus do that's SO much better. We've clearly done a crappy job articulating this publicly (we must have a crack marketing team), but we do have (what we believe) is a much better approach.

We have what no one else has: complete control over the Wi-Fi signal path. Our Smart Antenna array provides over 4000 different antenna combinations (read Wi-Fi signal paths) that can be used to get to any client.

Complete control of the Wi-Fi signal path means that our Smart Wi-Fi system focuses RF energy ONLY where and when it's needed. This "beam" of RF energy is effectively "formed" and directed toward the requesting client and no other places where its not needed. So by definition, we are a better neighbor. 

As a result, yes our signals go much much farther, but like the analogy above, our signals are focused within a tube (if you will) so others can't really hear them. Unless they are directly in the same path as the requesting client is at the specific time the client has access to the medium.

That's the deal.

Comments

[John Jackson]

You don't know anything about RF, which is pretty cool that you get to write this stuff. Transmit beamforming does nothing to prevent an attacker from getting your signal. It only improves the client's SNR. No tubes, that's not how it works. I'm sorry you can't see that, but when someone uses a high-gain antenna against your products, then you will learn the lesson the hard way. Stop shining on innocent people.

[Tony]

You obviously don't understand how RF barrier works I have seen an article from a reliable web site and it's not at all what you describe. But it's may be your purpose, fool people...

[coach suitcase]

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