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July 2013
August 2013

2013-07-05 »

Here's a (somewhat vendor-biased) pretty good introduction to wifi beamforming.

In short, Cisco claims 7-12 dB of signal strength improvement (in both upstream and downstream) through their beamforming stuff, and the 802.11n client only needs one antenna and no explicit beamforming support.  Which is a pretty big deal, if I'm interpreting correctly (10 dB should be equivalent to a 10x improvement in signal-to-noise ratio). I'm not really clear how this compares to any other/non-Cisco wireless modules, or how common beamforming is, or what.  One of the points of this paper is that some multi-antenna setups don't make very good use at all of the multiple antennas, compared to this DSP-based beamforming stuff.

That said, this DSP-based beamforming concept translates into a really big sensitivity to software problems.  It's not very hard to wire up some antennas, but a tiny little error in the math formula could completely destroy your beamforming performance, which means a 10x reduction (if your beamforming is ineffective) or worse (if your beamforming weakens the signal by accident) in SNR vs. the expected performance.  And testing this stuff must be absolutely crazy.

This may have everything or nothing to do with our GFiber wifi signal strength issues.

I think I'm in desperate need of some kind of remedial wifi signal strength training.  Does anyone around here know about this stuff?

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