01-17-2014 01:23 PM
First, thank you for creating the excellent whitepaper 802.11ac In-Depth. I found it extremely useful and very well written.
My question is around a statement made on the Aruba post here:
In particular the block of text reads:
"The one catch with MU-MIMO is that it will require new client hardware since both the AP and client need to be designed with the MU-MIMO capability. Therefore it will take until 2016, after the Wave 2 chipsets appear, for clients to become pervasive and be able to leverage the benefits of MU-MIMO."
Would it be possible to elaborate / clarify this statement as it is quite signicant on the Wait for Wave 2 vs. Deploy Wave 1 today decision?
Based on the Aruba 802.11ac In-Depth whitepaper, it would appear the Wi-Fi alliance will have another certification round for Wave 2 devices. I am not sure exactly what they plan on making mandatory vs. the IEEE 802.11ac standard.
Does the statement above mean that all the currently shipping 802.11ac client side hardware/chipsets will not be able to support MU-MIMO when the functionality ships on the AP or that they may have the functionality today but it is not part of the Wi-Fi Alliance 802.11ac Wave 1 certification efforts so it is an unknown if it will work? There is a Twitter thread on this topic here: https://twitter.com/80211Alan/status/4151278913878
Based on what I could find online, it appears the client side 802.11ac device would have to support the following functionality for MU-MIMO support:
Chapter 4. Beamforming in 802.11ac
"Because 802.11ac beamforming is based on explicit channel measurements, both the transmitter and the receiver must support it."
802.11ac In-Depth: Statement of Wi-Fi Alliance Certification Wave 1 / Wave 2
PDF Page 45:
"The Wi-Fi Alliance is under-reported in this paper because its work takes place a little later than the IEEE, selecting
parts of the standard and developing from them an interoperability certification.
But it plays a crucial role, as developers will build equipment to the eventual Wi-Fi Alliance certification rather than
the IEEE standard. In the same way as 802.11n certification rolled out in two phases, 802.11ac will generate at least
two Wi-Fi Alliance certifications over time."
01-17-2014 08:02 PM
Per our Product Team, the currently shipping 802.11ac hardware will not support MU-MIMO. The chipset solution in our 11ac APs does not contain the logic/circuitry necessary to support MU MIMO.
This is the case for all solutions from all vendors in the Wi-Fi industry.
New hardware based on wave 2 chipsets will be developed as they become available.
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01-17-2014 08:26 PM
Do currently shipping Wi-Fi certified 802.11ac clients have the capability to interoperate with MU-MIMO once the AP hardware is upgraded to 802.11ac Wave 2?
01-17-2014 10:43 PM
Acknowledged that. As per discussion with Broadcom so far, existing client devices will not support MU MIMO.
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