2. MIMO multiplies

I spent some quality time in both Atheros and Video54's rooms to get the details on their MIMO approaches. One of the things I learned is that I've been confused in the number of antennas and radios that the three currently-announced MIMO approaches use. So to set the record straight, here's a handy table:

You'll note from the table that Video54 uses only one radio, but has the most antennas, which are connected via software-controlled RF combiners. The company's "secret sauce" lies in the design of those antennas and the signal processing that constantly controls which of them are used for transmit and receive. Video54 says their MIMO implementation provides up to 20dB of signal gain.

You can see a couple of the printed-circuit antenna designs in the picture below, which also shows the Video54 reference AP design. Note that this is not necessarily what the NETGEAR product will look like and the Video54 folks properly directed me to NETGEAR for all those details (which I didn't get).

Video54 MIMO Reference design with antenna samples

One of the cool features that the Video54 design team came up with were LEDs near each antenna. Originally added as a debugging feature and each antenna's LED is lit only when it is used for transmit or receive. When I saw how the lights behaved while the obligatory demo video was being streamed, I thought that it so effectively showed how their MIMO implementation worked that I took a little video.

Video54 MIMO in action

You can click here to download the AVI clip (about 1 MB) and see Video54's MIMO doing its thing. Note again, that these LED's are part of the Video54 reference design and may not necessarily appear in retail products.