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I'm looking at a laptop and comparing the "Advanced-N+" with the "Ultimate-N" versions. I'm confused as to how more antennas might make a difference.

What really is the difference? Just better signal and range or some form of higher speed transfer?

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It won't be faster. It would I believe support multiple channels at once. –  Ramhound Jul 19 '11 at 16:41
    
@Ramhound: Why (as a typical user) would I care if it's using multiple channels? –  Billy ONeal Jul 19 '11 at 16:45
    
I think it has to do with either MU-MIMO and/or Beamforming; en.wikipedia.org/wiki/Multi-user_MIMO en.wikipedia.org/wiki/Beamforming –  jftuga Jul 19 '11 at 16:55

1 Answer 1

See this web page: Cisco ClientLink: Optimized Device Performance with 802.11n

To understand how this works, consider a single transmitter 802.11a/g client sending an uplink packet to an 802.11n access point with multiple transceivers. The access point receives the signal on each of its three receive antennas. Each received signal has a different phase and amplitude based on the characteristics of the space between the antenna and the client. The access point processes the three received signals into one reinforced signal by adjusting their phases and amplitudes to form the best possible signal. The algorithm it uses, called maximal ratio combining (MRC), is typically used on all 802.11n access points (see Figure 2). MRC only helps in the uplink direction, enabling the access point to "hear" the client better.

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What does this do for me as a user? I know one has two antennas and one has three, but why would I care? (I'm trying to get at the "so what? factor") –  Billy ONeal Jul 19 '11 at 21:03
    
The last sentence: the AP can 'hear' the client better. –  jftuga Jul 20 '11 at 1:47
    
Does that mean transfers will be faster? That range will be better? E.g. what does the AP "hearing the client better" do for me? Obviously I would expect the AP to "hear" the client better, there is a third antenna! –  Billy ONeal Jul 20 '11 at 16:16

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