Is AP-3602 a 3:4:3 or a 4:4:3 ?

[maross]

If the nomenclature is x:y:z, where x = transmitters, y = receivers, and z = spatial streams, and the 1262 is 2:3:2 (two TX, three RX, 2 streams), then what is a 3602 ?

I've seen both 4:4:3 and 3:4:3.  Are there three or 4 transmitters ?  I get there are four receivers.

[blakekrone]

There are 4 transmitters and 4 receivers with 3 spatial streams.

I interviewd Neil Diener and Walt Shaw on my podcast talking about these features:

http://nostringsattachedshow.com/2012/02/01/e04-cisco-3600-ap-launch/

[maross]

OK - so what does the 4th transmitter do. If you have three spatial streams, then the 4th transmitter can't augment any one stream because that would cause an imbalance.

I can see where the 4th transmitter might be used for legacy beamforming, but what do you do with four that you can't already do very well with three ?

I would understand #4 being used to help differentiate the other three - similar to how the 1262 used the #3.

Confused - I am.

[blakekrone · Accepted solution]

4 transmitters allows you to beamform to 802.11n devices. You can't beamform to 802.11n devices with 2 transmitters. The more transmitters and receivers you have the better perceived signal you can acheive on each end when you combine the RF data streams.

This is a good article that goes over in detail the benefits of the multiple transmitters/receivers and spatial streams:

http://www.cisco.com/en/US/prod/collateral/wireless/ps5678/ps10092/white_paper_c11-516389.html

[maross]

Does that then mean that when beamforming to an 802.11n client, there will be two streams, beamformed, thus 4 transmitters, but you won't be able to beamform 3 streams ?

That at least would make sense to me.

[Stephen Rodriguez]

No, the beam forming will use all four transmitters to send the data so that the client receives it in the best possible way.

Fred had a really great slide that illustrated this.  Hopefully they get it posted on the partner community.

Steve