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Why Cisco dosn't have AP MIMO 3x3 but only 3x2?

More player has a portfolio APs MIMO 3x3? Why Cisco no has APs with these caracteristics but only 3x2?

AP 3x2 i very similar in term of perfomance to AP 3x3?

If you should to chose a solution for your company, the MIMO 3x3 funtionality is avery important for the project or MIMO 3x3 and 3x2 is not the same but is very similar?

Redards.

Mirko Severi.

3 REPLIES
Hall of Fame Super Silver

Re: Why Cisco dosn't have AP MIMO 3x3 but only 3x2?

I really can't answer that, maybe one of the Cisco guy's can:), The bottom line is that 802.11N is limited to 300mbps no matter if its a 2x2, 2x3 or 3x3.  How I see it from my client side, is how many wifi devices will actually have a 3x3 sytem in it and what gains will they get from a 3x3 vs a 2x3.  If you see Cisco come out with a 3x3, you will also see the cost go up for sure.  Now what will happen to the power requirements... do you now need to supply more power to actually use the 3x3? If you review the others who have 3x3, you will notice that they mention about the power requirements or else it will drop down to a 2x3 configuration.  Would it be nice.... of course, only if you can keep you existing infrastructure and the cost doesn't jump up 100+ dollars per AP.  Most of my clients still have non 802.11N devices and I don't see that from going away.  Just my opinion:)

Here are some links that compare them:

http://www.networkworld.com/newsletters/wireless/2009/110909wireless2.html

http://www.eetimes.com/design/communications-design/4012601/Optimizing-WLAN-performance-with-MIMO-calls-for-careful-analysis

-Scott
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Hall of Fame Super Gold

Re: Why Cisco dosn't have AP MIMO 3x3 but only 3x2?

Q. What are the differences in performance between a 2x3 and a 3x3 MIMO implementation?
A. Theoretical calculations show that a 3x3 radio will have slightly better performance over a 2x3 radio. However, in our real world performance testing we have not seen any significant performance differences between 2x3 and 3x3 implementations. Note that the current generation of both 2x3 and 3x3 802.11n silicon supports up to 2 spatial streams, so there is no throughput advantage for a 3x3 implementation.

Hall of Fame Super Silver

Re: Why Cisco dosn't have AP MIMO 3x3 but only 3x2?

To add to this, both the 2x3 and 3x3 uses 2 streams, so the 3x3 doesnt' mean that it actually uses 3 streams.  From the last link I posted:

For 2-stream spatially multiplexed MIMO systems, both the 2x3 and 3x3 architectures offer significant performance benefits over the conventional 2x2 configuration for little additional cost. Thus, for access points with larger power budgets, 3x3 is the optimal configuration, while client solutions benefit the most with a 2x3 configuration.

-Scott
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