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Are there any difference for phone battery life when connected to 5 GHz access points vs connecting to the same at 2.4 GHz?

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    Not noticeably. Theoretically, 5GHz should use more power than 2.4GHz, but not significantly. What's more important are the usability aspects of 5GHz vs 2.4GHz. – negusp Nov 21 '16 at 1:14
  • @Patrick Negus: What are the usability aspects you mean? Coverage, hardware support by variety of devices, anything else? – Sergey Sergeyev Nov 21 '16 at 9:21
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    2.4 GHz has better coverage as it has a lower frequency and thus can penetrate barriers more effectively; 5 GHz is faster within acceptable distances, however, due to its higher bandwidth; finally, there are many more 5GHz channels available (and fewer devices that utilize the 5 GHz band), and so snooping and overcrowding become less of an issue. – negusp Nov 21 '16 at 21:17
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The coverage issue will have something to do with power usage.

When comparing 5 GHz battery drain vs. 2.4 GHz, a lot depends on the coverage you are in with respect to each frequency band.

5 GHz (for the same power) lacks the range of 2.4 GHz. Objects (depending on material) can obstruct 5 GHz more than 2.4 GHz (sometimes not depending on material).

So, if I get 3 bars of 2.4 GHz in the furthest away part of the house (the upstairs bedroom) but only 1 bar at 5 GHz, my phone will likely have more trouble keeping in touch with the access point and that translates to more packets exchanged, a slower throughput (and that means more on-time for your 5 GHz radio and the system generally), and this will burn more battery.

If you have good 5 GHz coverage and 2.4 GHz coverage in the same area, using 5 GHz is likely as good (if not a bit better) as it will pull faster, then wind down vs. the 2.4 GHz. When coverage starts getting worse for the 5 GHz, but not the 2.4 GHz, you may want to switch to 2.4 GHz for battery reasons.

Factors impacting your performance:

  • Distance from AP

  • Quality of your 2.4 GHz and 5.0 GHz antennas both in the phone and the AP (should be roughly similar but...)

  • Other nearby networks using the same 2.4 GHz or 5 GHz channels your devices want to use (channel contention and/or interference)

  • Other RFI (interference with the radio bands you care about - badly shielded microwaves or other energy emitters that might shed harmonics off into your APs radio bands)

  • What you are using your device for (the occasional short message or long many MB movie streaming) as this will emphasize or de-emphasize performance and coverage distances (two identical devices on different bands sitting mostly idle probably won't see notable battery differences, but two streaming hard most of the time may well see not only the difference in battery from streaming, but further degradation in charge based on if the 5 GHz is in poorer coverage)

  • Materials between your portable device and your AP

I'm likely missing a few other factors and how significant each one mentioned is depends a lot on the gear, the interference/contention in the area and the types of material, as well as the usage pattern for the device.

But generally - poorer coverage -> more battery use, so if 2.4 GHz is showing more bars than 5.0 GHz, shift to 2.4 GHz.

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  • The coverage of 2.4 GHz is only better if you don't have a neighbors with interfering 2.4 GHz signals... – Robert Jan 2 '18 at 18:37
  • That's why I said there were factors including "Other nearby networks using the same 2.4 GHz or 5 GHz channels your devices want to use (channel contention and/or interference)" in the summary at the end of my original post. Channel contention is much more likely than actual RFI (harmonics or other forms of interference not expected, unlike two sets of devices with overlapping coverage set to use the same radio channel from which you would expect channel contention as they try to share a resource (the radio channel)). There are free tools to assess channel use by local networks. – user3055321 Jan 5 '18 at 8:21
  • Two aspects of user3055321's fairly complete answer are unclear to me: 1. Is there any difference in the amount of energy to generate a 5 GHz vs. 2.4 GHz signal? (And is that amount significant?) [Physics/radio] and 2. – user3055321 Jul 16 '18 at 0:48
  • 2. Are the protocols similar in terms of packet sizes (impacts fades and other Tx failures) and retrransmit windows (also impacts retransmit overheads)? I suppose error correction tech can.also impact net overhead. This may already be boiled into performance in poor coverage if not explicitly called out. – user3055321 Jul 16 '18 at 0:59
  • The Wifi sending power depends on the country you are in, as the max sending power is very different: w.wol.ph/2015/08/28/maximum-wifi-transmission-power-country – Robert Jul 16 '18 at 7:32

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