Why is TxBF limited to the R710?

[john_d]

I recently got an R710, and in playing around with it, I've noticed that some of my devices are using a MCS rate that includes "/2/BF", which seems like it's using 4 radio chains to do 2-stream TxBF in addition to BeamFlex? Very cool 🙂

I also noticed that the support info for the R710 on 9.12 shows a lot of info about TxBF sounding frames and such, which is missing from the R600/R700. Is there a particular reason that the R710 supports TxBF but the R600/R700 does not?

FWIW, I'm also noticing that the R710 is able to deliver good 802.11ac speeds to Wave 1 devices at a longer range. Even through 2 walls, I'm seeing 300mbit on a 3x3:3 Wave 1 client when an R600 just a few feet away can only deliver 400-450mbit to the same client. Looks like it's a compelling upgrade even if you don't have Wave 2 capable clients!

[seanmuir]

As you were talking about souding frames I assumed you were on about Wave 2, as responding to sounding frames is a Wave 2 option.

[john_d]

Sounding frames were even defined for 802.11n, and as far as I can see from the 802.11ac spec, implicit and explicit sounding are simply described as "optional" and are not confined to Wave 2 only. It could be that the hardware for Ruckus Wave 1 AP's don't support 802.11ac transmit beamforming and that was just added for Wave 2... but in which case, what does Ruckus mean when the data sheets for R500, 600, and 700 all say "Transmit Beamforming Capable"?

There are specific sounding frames that appear specific to DL MU-MIMO, but that's another story, and of course, I don't expect support those on a wave 1 AP.

[john_d]

http://community.arubanetworks.com/t5/Technology-Blog/11ac-Beamforming-Makes-the-Dog-Rollover/ba-p/1...


In fact, Aruba has had 802.11ac beamforming since wave 1, and implied that it's a limitation of the Wave 1 QCA chipset vs the Wave 1 Broadcom chipset that transmit beamforming isn't supported. Well, I guess that answers my question.

[seanmuir]

There are specific sounding frames that appear specific to DL MU-MIMO, but that's another story, and of course, I don't expect support those on a wave 1 AP.

We are on the same page then, as your orginal question was regarding TxBF sounding frames, which made me think your question was regarding Wave 2:

I also noticed that the support info for the R710 on 9.12 shows a lot of info about TxBF sounding frames and such, which is missing from the R600/R700. Is there a particular reason that the R710 supports TxBF but the R600/R700 does not?

As for Aruba... there not my cup of tea.

[john_d]

No worries — and don't get me wrong, I'm not implying that Aruba is better, and as the comments show, their testing results were not replicated by some of the commenters.

I'd rather have BeamFlex+ over 802.11ac TxBF any day, but it sounds like the best-of-both-worlds is having both, at least that was heavily stressed in the R710 marketing materials.