Beamforming: The Best WiFi You’ve Never Seen

The Client That Could Be

Ever since the days when 802.11a/g grew a second antenna, we’ve had “transmit/receive diversity,” which sends the same data stream out over multiple antennas and simply lets the access point select whichever antenna is receiving the best signal. Applied to 802.11n, transmit diversity used multiple antennas to help increase range and better deal with difficult locations. This is why 11n does a generally better job than 11a/g at eliminating dead spots.

However, 802.11n equipment got another jump in intelligence with the addition of maximal ratio combining (MRC). This technology combines multiple antenna signals in such a way that strong signals are multiplied while weak signals are attenuated. The signals you want get boosted, while those you don’t have their power cut. MRC is built into all 802.11n chips.

Now, as you might expect, the receiving end can play an important role in optimizing chip-based beamforming. With 802.11a/g, access points could listen to the client and use rudimentary MRC analysis to boost power along the best-suited beam, providing a gain of roughly 1 to 2 dB. The catch here is that the access point was doing all the work. There was no active feedback coming from the 802.11a/g clients.

With “implicit beamforming,” wherein an 802.11n AP is communicating with 802.11n clients, you can have some feedback. Rather than having the access point perform all of the signal analysis, it can query the client and see if it agrees that this or that particular beam orientation is optimal. Having this limited two-way communication yields a maximum of 3 dB additional gain, but the bad news is that there are currently no products on today’s market supporting implicit beamforming.

With “explicit beamforming,” feedback between the AP and client happens much more frequently. This way, if a client moves or an antenna gets adjusted or anything happens to alter the dynamics of the signal strengths, the system is able to adapt almost instantaneously to a new, optimized configuration. Again, having the client involved in this way can yield up to a 3 dB benefit with two radios, but there are no products available today offering this capability. Hopefully this will change.

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  • antiacid
    awesome article! Thanks for exposing us to this great technology :)
  • Other Comments
  • dingumf
    Tyra is an over confident wh0r3 and is not hot.

    You sir are an idiot
  • pirateboy
    just what we need, more retarded failnoobs clogging up the airwaves with useless braindead movieclips...yaay
  • chinesemafia69
    wow....this owns
  • bucifer
    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.
  • Mr_Man
    In defense of your wife, you didn't HAVE to use that particular channel to view all the "detail".
  • Anonymous
    @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
  • antiacid
    awesome article! Thanks for exposing us to this great technology :)
  • Pei-chen
    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.
  • zak_mckraken
    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!
  • jerther
    There is so much invisible to understand in wireless technology!
  • ebattleon
    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.
  • Anonymous
    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?
  • Rancifer7
    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.
  • chaohsiangchen
    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.
  • scotty123
    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?
  • williamvw
    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.
  • williamvw
    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
  • williamvw
    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.
  • bounty
    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.
  • williamvw
    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?