do the 802.11n / 5GHz devices use more power?

[mcveigh]

I was just wondering if a device using 802.11N would need more, less, or about the same amount of power. Would it depend if it was 2.4 or 5GHz?
I was mainly thinking of small battery powered devices like tablet's, cell phones, etc. Would you see any extension in battery life by using one type or another?
or does the frequency/tech really not affect things that much?

 

[pitz]

Here's a good academic paper on the topic:

http://ils.intel-research.net/uploads/papers/80211n_power.pdf

Of course, details are obviously highly implementation-specific.

5GHz has a much higher degree of attenuation than 2.4GHz, so you really need to use a lot of TX power, or some fairly high gain antennas, to achieve what you'd be achieving in the 2.4Ghz band with lesser power/lower gain antennas (gain is generally related to directionality).

802.11n generally implies multiple RX/TX chains ("MIMO") for the extra bandwidth -- these chains obviously take up extra power, but, practically speaking, may or may not be useful, depending on actual conditions.

 

[DainBrammage]

Are talking actual power consumption or PoE draw?

The quick and easy answer is yes, True N will use more power because depending on the flavor it can have multiple radios. Standard G is a single radio standard A is a single radio but N comes in multiples of radios.

 

[pitz]

Are talking actual power consumption or PoE draw?

His comments were sort of hinting at embedded radios. So I don't see how PoE means anything.

The bottom line is that for the same range, a 5GHz radio will have to drive a lot more power, and 802.11n MIMO requires far more DSP than a SISO radio that would be typical of 802.11a/b/g.

But an 802.11n radio may very well be more modern and use an even lower-power process for the DSP than the older 802.11a/b/g radios, so a 802.11n implementation may very well be more efficient than an older-generation product. There are probably few implementations using the most modern SoC technology of 802.11a/b/g radios, so you're essentially comparing old to new.