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Test Apps And Methods

Beamforming: The Best WiFi You’ve Never Seen
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I used two applications during testing, Zap and Chariot. These examine UDP and TCP packet performance, respectively. You don’t see UDP tested very often. Everybody simply loads up Chariot or iPerf, does some time tests, and that’s about it. For conventional file transfers and similar everyday tasks, this is an appropriate methodology. However, UDP is what you use for streaming video. It’s a faster protocol because the server system doesn’t have to sit around waiting for receipt confirmation from the client. With UDP, you simply blast out a stream of high-speed packets and hope they get to their destination, come what may.

You’ve probably never heard of Zap because Ruckus developed it in-house for testing video streaming performance. To the best of my knowledge, this is the first extensive use of the tool in a mainstream review. As it was, I was sworn to not let the application out of my sight, so apologies in advance for not making it available to readers.

With that said, there’s no dark magic to Zap. It simply takes a reference load of data and sends it between the server and client using UDP. The transfer is divided into percentages of the total work load, with each step being one-tenth of a percent. At each step, throughput rate is recorded and the number shown by the software is the lowest packet speed recorded up to that point in the transfer job. This is why Zap numbers look really fast at 1%, average at 50%, and very slow at 99 percent. 

For our purposes, we’re most interested in the average and lowest numbers. When it comes to video, you don’t care what the fastest or average sustained rates are. You care about the slowest speeds, the weakest link in the wireless chain, because this will be the key factor in determining your video-watching experience. If you sustain a 70 Mbps connection 95% of the time but occasionally drop to 15 Mbps for whatever reason, then those drops are going to translate into dropped frames and hiccups if you’re watching an HD stream with a 19.2 Mbps data rate. You can see a real-world example of this in the chart shown here, which (spoiler alert!) is the Chariot throughput data for Cisco’s 1142 access point at short range.

As mentioned previously, many things can impact wireless throughput, including the orientation of the client. There are three antennas in most 802.11n-equipped laptops, and in three dimensions these work (once again) a lot like rabbit ears. So I actually ran each test four times, rotating the laptop a quarter-turn for each test. The results were then averaged together.

Additionally, since each access point has the ability to run at either 2.4 or 5 GHz, I ran all tests on both radio bands. It’s possible for a client that associates on one band to hop to the other if conditions deteriorate, but it’s not common. Client sessions tend to stay loyal to whichever band they first associate with. Hence it’s important to get a good idea of how both bands perform.

Not least of all, I made sure that power management in the Intel client driver was set to “highest.” Otherwise, when running on battery power, performance can be more prone to fluctuation. If you’re curious, that command line business sitting under the driver window shown here is Zap at rest.

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Top Comments
  • 10 Hide
    antiacid , August 17, 2009 1:13 PM
    awesome article! Thanks for exposing us to this great technology :) 
Other Comments
  • 2 Hide
    chinesemafia69 , August 17, 2009 8:16 AM
    wow....this owns

  • -6 Hide
    bucifer , August 17, 2009 8:42 AM
    This article started up pretty good with lots of technical data and the beamforming technology in theory but after that the goodness stopped.

    1.You cannot compare two products by testing them with a in-house developed software. It's like testing ATI vs nVIDIA with nvidia made benchmark.
    2.If you do something get it done, don't just go with half measures. I don't care if you didn't have time. You should have planned this from the beginning. The tests are incomplete, and the article is filled with crap of Rukus and Cisco.
  • -5 Hide
    Mr_Man , August 17, 2009 12:44 PM
    In defense of your wife, you didn't HAVE to use that particular channel to view all the "detail".
  • 2 Hide
    Anonymous , August 17, 2009 12:58 PM
    @Mr_Man: With a name like yours, I'd think that you'd sympathize with Chris a bit more :p  Unless (Mr_Man == I likes men) :D 
  • 10 Hide
    antiacid , August 17, 2009 1:13 PM
    awesome article! Thanks for exposing us to this great technology :) 
  • -4 Hide
    Pei-chen , August 17, 2009 1:17 PM
    Both Tyra and Heidi have personal issues and would be pretty difficult friend/mate.

    The network idea sounds better. I couldn’t get my 10 feet g network to transmit a tenth as much as my wired network without it dropping.
  • 3 Hide
    zak_mckraken , August 17, 2009 2:23 PM
    There's one question that I think was not covered by the article. Can a beamformaing AP can sustain the above numbers on two different clients? Let's say we take the UDP test at 5 GHz. The result shows 7.3 Mb/s. If we had two clients at opposite sides of the AP doing the same test, would we have 7.3 Mb/s for each test or would the bandwidth be sliced in 2?

    The numbers so far are astonishing, but are they realistic in a multi-client environnement? That's something I'd like to know!
  • -1 Hide
    jerther , August 17, 2009 2:28 PM
    There is so much invisible to understand in wireless technology!
  • -6 Hide
    ebattleon , August 17, 2009 3:01 PM
    You can of course get the same effect by having better antenna on both ends of the network. This would increase gain which would improve signal to noise ratio, which would improve data flow speeds. You would also get the same effect by boost in the power but that could get you in trouble with the law.

  • 1 Hide
    Anonymous , August 17, 2009 3:04 PM
    I'm not an expert on beamforming, but I'm surprised that it is useful at these frequencies. After all, the wavelength at 2.4 GHz is ~12 cm (~5 inches). That means that the pockets of constructive interference (the beam) are very small. Moving the receiver a few inches should make a big difference.

    Are you sure the differences you are seeing aren't simply due to higher power output? Couldn't the same improvements be obtained with a directional antenna like a Yagi?
  • 1 Hide
    Rancifer7 , August 17, 2009 4:00 PM
    So far quite an interesting technology. Its nice to know that at someone in the wireless world is striving to make something innovative!

    When all the major players sell items that look almost the same, act similarly, and perform almost the same, there is something wrong with the industry.
  • 1 Hide
    chaohsiangchen , August 17, 2009 4:13 PM
    Beam forming technology have been for a long time, but they are mostly used in military equipments. Phased Array radars, Synthetic Aperture Radar, Inverse Synthetic Aperture Radar, Plane Array Antenna and antenna for data link. Most consumer products still use Yagi or disk antenna. Cost is a major issue in the application. Military don't care that much about the cost.
  • 0 Hide
    scotty123 , August 17, 2009 4:23 PM
    sounds nice - but i won't get excited until it's available at Best Buy!

    One niggling concern, I felt reasonably safe with the unfocused cloud of RF surrounding me wherever I go, but I am not so sure about the tightly focused beam that the Ruckus provides. What happens to the poor joe who sits directly in the path of such a beam for 8 hours a day?
  • 1 Hide
    williamvw , August 17, 2009 4:39 PM
    Mr_ManIn defense of your wife, you didn't HAVE to use that particular channel to view all the "detail".

    LOL! True enough. It honestly was a reference file I had on hand for such testing situations. Angelini obviously showed a bit more wisdom in his choice of in-house test content.
  • -1 Hide
    williamvw , August 17, 2009 4:44 PM
    scotty123sounds nice - but i won't get excited until it's available at Best Buy! One niggling concern, I felt reasonably safe with the unfocused cloud of RF surrounding me wherever I go, but I am not so sure about the tightly focused beam that the Ruckus provides. What happens to the poor joe who sits directly in the path of such a beam for 8 hours a day?

    My absolutely unqualified opinion is "probably nothing." While the conditions are somewhat different, you might want to read a Tech Myths column segment I did over on Tom's Guide that touches on this issue. http://www.tomsguide.com/us/decibels-noise-canceling,review-1338-10.html
  • 2 Hide
    williamvw , August 17, 2009 5:17 PM
    zak_mckrakenThere's one question that I think was not covered by the article. Can a beamformaing AP can sustain the above numbers on two different clients? Let's say we take the UDP test at 5 GHz. The result shows 7.3 Mb/s. If we had two clients at opposite sides of the AP doing the same test, would we have 7.3 Mb/s for each test or would the bandwidth be sliced in 2?The numbers so far are astonishing, but are they realistic in a multi-client environnement? That's something I'd like to know!

    Excellent question, and one I hope to dive into in a later article. For now, I can only give you the anecdote on my opening page, running the same HD stream to two clients. Ruckus states that BeamFlex can sustain a 50 Mbps minimum per access point. Do the math on your client streams accordingly, I suppose.
  • -1 Hide
    bounty , August 17, 2009 5:24 PM
    williamvwLOL! True enough. It honestly was a reference file I had on hand for such testing situations. Angelini obviously showed a bit more wisdom in his choice of in-house test content.


    Honestly honey, it's just a reference file, I swear it's not porn. I challenge you to find HD streaming content from the internet that highlights the subtle nuance of flesh tones.
  • 2 Hide
    williamvw , August 17, 2009 5:28 PM
    bountyHonestly honey, it's just a reference file, I swear it's not porn. I challenge you to find HD streaming content from the internet that highlights the subtle nuance of flesh tones.

    Hey, the VS catalog mails to her, not me. I was merely trying to be a good husband and participate in her interests. ;-) ANYWAY. Back to beamforming, shall we?
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