3G vs WiFi when at home - which uses less power?

[Telexen]

So here's another interesting situation. Are any energy savings you're going to get by using WiFi going to be canceled out by the fact that you have the wifi adapter on all the time looking for networks at the same time as using 3G data (when no wifi is available)?

I've seen some apps on the market that turn wifi on/off depending on your GPS location. That sounds great, but then you have your GPS receiver on all the time!

What's stopping you from putting the Power Control widget on one of your home screens and turning off WiFi when you're not at home? That's what I'm doing now. Nice widget...wifi/bluetooth/gps/autosync/brightness toggle all in one.

 

[Flyboy1830]

So I notice that the default setting is that if your screen turns off, then the wifi turns off, thus switching to 3G. That makes me think wifi uses more power and the default setting is intended to extend battery life. This is pure conjecture, based on zero experimentation.

 

[knock]

If you have wifi active, it will auto connect to networks in range only if you have previously connected to that network and allowed auto connect for that network. When wifi is connected, it does take priority over VZ's data network, effectively disabling 3g. This is evident if you have visual voicemail. It tells you it can't get an incomming voicemail because the data network is unavailable and prompts you to close the wifi connection so it can connect.
I personally like to turn the various services on and off as I need them.
The power control widget that comes with the phone has wifi, bluetooth, GPS, and sync toggle buttons, and a brightness button.

I used to have a windows mobile phone with tethering and it did have a 5GB limit on it's "unlimited" plan, but the phone's data/email plan was unlimited. Tethering via PDAnet doesn't seem to tip off anything at VZ at this time, but I only use it infrequently.

If your wifi connection to the internet is faster than 1MB, then you can pull more data in the same time via wifi than with 3g. Often wifi is considerably faster. (5-10x) I can't tell much difference with web browsing, but when transferring larger files, or using YouTube, wifi is noticably better (YouTube will auto-switch to HD in some cases). Using Speedtest, my 3g connection averages 750-900 KB up AND down. It is close to the same when tethered. Again using Speedtest from my phone, my wifi averages 7MB down and 1.5MB up. Like I said, a considerable difference. HOWEVER...
Using wifi, I don't seem to be able to download large files (500mb+) directly to the phone as quickly as I can download the same file to my PC through the same router.

I'd be interested in any information anyone has about tweaking the wifi connection for optimum performance.

 

[bigdroiddog]

I bet 3G uses more power because it's got to transmit further, WiFi will only go a few hundred feet but 3G goes all the way to a cell tower. So it's little transmitter needs more power to transmit.

I keep mine set to 3g because every time i switch to wifi in my home it just eats battery. I have not tested this since the 2.01 update but before that update wifi sucked the life out of my phone it seemed. PLus if we are all on unlimited plans what does it matter, why save on data usage? I live in the country, fortunately i get all bars of verizon service but crappy hi speed internet service, using speed test i have faster DL speeds on wifi but faster upload speeds on 3g, i know that's pathetic.

 

[MigsArte]

droid newbie here, how can i turn off just 3G? i used to do it with the iphone.
thnx!

 

[Icedemon]

droid newbie here, how can i turn off just 3G? i used to do it with the iphone.
thnx!

I seen an app in the market that did this. i think the name of it was 3G off or something like that.

 

[windstrings]

My wifi turns itself on and auto connects to networks, I don't know what your talking about? If there is wifi in my area, my 3g turns off and wifi turns on. You do need to connect it the first time, but once it recognizes a familiar network it will detect and connect.

How do you know your 3g is turning off when your connected wifi?

I"ve always assumed wifi was for internet uses but phone calls etc are still rounted through 3g?

When I connect to wifi... my 3g icon at the top still remains showing how strong my signal is "it doesn't go away"... if I turn off wifi, my wifi icon goes away but the 3g remains unaffected.

How do you know your 3g is going off when wifi is connected?

 

[cdodge]

I guess "off" was not the word I was looking for. Im not sure why I would turn it "off". However, when there are no wifi networks in range, 3g will turn on. If i connect to a wifi network 3g turns off. I suppose it just "sleeps", as opposed to turns "off"

the imagio has a feature like this, so its realistic for the droid.

 

[windstrings]

Ah... my 3g icon disappeared indeed when hooked to wifi.. problem is.. I couldn't get it back once I disconnected from wifi... I had to reboot to get my 3g back up.

Now I can flip back and forth and it works.... don't know whats up with that.... maybe an app jammed it.

 

[KeithG]

Unless you change the default wifi sleep policy. The question is slightly moot

1) you need to have wifi enabled, and it must be connected to an SSID for the handset to remember it. The handset will not (in a default state) connect to an unknown SSID.

2) the wifi sleep policy will disable the wifi after the inactivity period once the handset screen is turned off. The wifi sleep policy is under home > menu > settings > wireless & networks > wifi settings > menu > advanced. In the default configuration, the sleep policy is to turn off if the screen is off (after the IDLE timer runs out).

12-27 01:45:39.404: DEBUG/WifiService(1014): ACTION_SCREEN_OFF
12-27 01:45:39.435: DEBUG/WifiService(1014): setting ACTION_DEVICE_IDLE timer for 900000ms

900000 ms = 900 sec = 15 minutes. At the conclusion of this time, if no user input is given, the wifi will turn off. Data requests, will then be carried out by the 3g modem. You can see this some times, when you wake up the phone and your wifi isn't connected. You'll see the 3g icon, and it will then quickly switch back to the wifi connection (if available).

The difference between 3g or wifi, rather comes down to localized variables. The most power consumption on any radio (wifi or cellular) is at what transmit power does the radio need to obtain for the receiver to accept the transmission without errors. This in itself is factored by a slew of variables.

For some ppl. Keeping the phone on 3g will be better, others, keeping it on wifi might be better.

Keeping the phone from having to transmit and the cpu spun down to the lowest sleep state is what will keep the phone running the longest. But ... at that point its a brick that your paying for

BTW this is when the app spare parts is handy for looking at what is waking up the phone the most.

Pushed data:

Depending on the application, it can be handled differently, but within general terms. Push data such as say an IMAP IDLE command, keeps a long living TCP connection open and waits for the other end to send data. Since the phone is running a Linux networking stack, exploring the /proc/sys/net/ipv4/tcp_keepalive_* settings will tell you how often the phone will "check" on the connection. Unless android or the handset manufacturer changed the settings, they default to 7200 seconds (2 hours), before the network stack will test to see if the TCP connection is still alive. The application can of course send data way before this to check for itself.

If your running a common DLINK or linksys WAP on your DSL or cable / fiber connection, the router itself may clean up these connections to the outside world in as little as 5 minutes. If the NAT/Firewall doesn't see traffic via that TCP connection for over 5 minutes, it may "forget" it. Sometimes this is directly configurable by the user. Sometimes not. If the NAT device is nicer it may have a soft limit, allowing the connection to persist until it starts running out of ports, in which it will start to reclaim these orphaned connections.

Applications that use lots and lots of connections can cause the stateful packet filter portion to starve of connection tracking slots, causing it to reclaim these older connections. P2P, bit-torrent, etc.. or just several users hammering away..... if the NAT / router is nice it will send a close FIN/RST tcp packet to the handset telling it that connection is no longer valid. Phone wakes up, tells the upper layers, and then the connection is re-established ...

Or the phone during its wake up period, checks up on the connection finding out its dead, and then again, has to re-up the connection.

This all happens whether its 3g or wifi... Wifi, in certain circumstances may make for a more hostile environment where the phone has to constantly wake up every few minutes to find out that its connection is dropped.

So really its comes down to... how often and at what TX power.

and .... then the phone after 15 minutes:

12-27 02:05:50.209: DEBUG/WifiService(1014): got ACTION_DEVICE_IDLE
12-27 02:05:50.217: INFO/wpa_supplicant(2673): CTRL-EVENT-STATE-CHANGE id=1 state=8
12-27 02:05:50.224: VERBOSE/WifiMonitor(1014): Event [CTRL-EVENT-STATE-CHANGE id=1 state=8]
12-27 02:05:50.224: VERBOSE/WifiStateTracker(1014): Changing supplicant state: COMPLETED ==> DORMANT
12-27 02:05:50.224: DEBUG/WifiStateTracker(1014): Deconfiguring interface and stopping DHCP
12-27 02:05:50.240: INFO/wpa_supplicant(2673): CTRL-EVENT-DISCONNECTED - Disconnect event - remove keys
12-27 02:05:50.240: VERBOSE/WifiMonitor(1014): Event [CTRL-EVENT-DISCONNECTED - Disconnect event - remove keys]
12-27 02:05:50.248: INFO/wpa_supplicant(2673): CTRL-EVENT-STATE-CHANGE id=-1 state=8
12-27 02:05:50.248: VERBOSE/WifiMonitor(1014): Event [CTRL-EVENT-STATE-CHANGE id=-1 state=8]
12-27 02:05:51.243: DEBUG/NetworkStateTracker(1014): setDetailed state, old =CONNECTED and new state=IDLE
12-27 02:05:51.287: INFO/wpa_supplicant(2673): CTRL-EVENT-DRIVER-STATE STOPPED
12-27 02:05:51.295: VERBOSE/WifiMonitor(1014): Event [CTRL-EVENT-DRIVER-STATE STOPPED]
12-27 02:05:51.295: VERBOSE/WifiStateTracker(1014): New network state is DISCONNECTED
12-27 02:05:51.302: VERBOSE/WifiStateTracker(1014): Changing supplicant state: DORMANT ==> DORMANT
12-27 02:05:51.302: DEBUG/ConnectivityService(1014): ConnectivityChange for WIFI: DISCONNECTED/IDLE
12-27 02:05:51.302: DEBUG/DataConnectionTracker(1076): enableApnType(default), isApnTypeActive = false and state = IDLE
12-27 02:05:51.302: DEBUG/DataConnectionTracker(1076): setEnabled(0, true) with old state = false and enabledCount = 0
12-27 02:05:51.310: DEBUG/DataConnectionTracker(1076): EVENT_APN_ENABLE_REQUEST 0, 1
12-27 02:05:51.310: DEBUG/DataConnectionTracker(1076):  dataEnabled = false, enabledCount = 0, isApnTypeActive = false
12-27 02:05:51.341: VERBOSE/ConnectivityService(1014): Attempting to switch to MOBILE
12-27 02:05:51.451: DEBUG/NetworkStateTracker(1014): setDetailed state, old =DISCONNECTED and new state=CONNECTING
12-27 02:05:51.459: DEBUG/ConnectivityService(1014): ConnectivityChange for MOBILE: CONNECTING/CONNECTING
12-27 02:05:55.076: DEBUG/NetworkStateTracker(1014): setDetailed state, old =CONNECTING and new state=CONNECTED
12-27 02:05:55.076: DEBUG/ConnectivityService(1014): ConnectivityChange for MOBILE: CONNECTED/CONNECTED

 

[gotwillk]

ok so if i leave my wifi setting turned on, and i'm walking around outside, and my screen is turned off, with the policy set to turn off when screen is off, will it continue to scan for nearby networks? and will this scanning drain battery?

and also, if i leave the policy to never turn off, will it scan for nearby networks when i'm walking around outside in the streets?

 

[aguillon5]

What I found out to do best for me is I only turn on wi-fi when I am actively using the internet. It is on 3g most of the time. I used to have connect at home whenever I was in range and that seemed to drain my battery a ton. If there is a way to turn off the 3g I would do that too. Sometimes I go hours without using the 3g or wi-fi so I wonder why this is not an option. Try it for yourself and post your results let us know how it goes.

 

[KeithG]

ok so if i leave my wifi setting turned on, and i'm walking around outside, and my screen is turned off, with the policy set to turn off when screen is off, will it continue to scan for nearby networks? and will this scanning drain battery?

and also, if i leave the policy to never turn off, will it scan for nearby networks when i'm walking around outside in the streets?

The wifi is off at that point. It isn't scanning. It won't do anything wifi related until you wake it back up. But it will be using the 3g connection.

 

[gotwillk]

The wifi is off at that point. It isn't scanning. It won't do anything wifi related until you wake it back up. But it will be using the 3g connection.

oh so if i turn the screen back on, the wifi will start scanning for signals again? and when i turn the screen back off, it'll stop?

so basically whenever i have the screen on, it'll continue to scan for networks.

 

[KeithG]

oh so if i turn the screen back on, the wifi will start scanning for signals again? and when i turn the screen back off, it'll stop?

so basically whenever i have the screen on, it'll continue to scan for networks.

Yes. The radio will have power, but scanning is a passive event. The radio is just cataloging beacon frames from access point broadcasts. Beacon interval on most ap's are around 100ms (10 times a second).

 

[windstrings]

thanks Keith... you taught me a thing or two......

in the same settings, I see the regulatory domain to set the number of channels to use, upon viewing it, I see choices of 11, 13, and 14.. none of which or chosen by default.... is there a recommendation and why?

 

[KeithG]

thanks Keith... you taught me a thing or two......

in the same settings, I see the regulatory domain to set the number of channels to use, upon viewing it, I see choices of 11, 13, and 14.. none of which or chosen by default.... is there a recommendation and why?

Wi-Fi - Wikipedia, the free encyclopedia

Different regions have sliced up the 2.4ghz spectrum a bit differently. The regulatory domain allows you to change the profile of what channels the radio will operate on and look for networks within. US = 1-11.

But for easier tooling this is either a firmware or software setting within the radio driver... so the manufacturers can ship the same silicon for integration into devices that may require channels 12-14.

 

[windstrings]

Thanks... so in the US I"ll just tell it to only operate within 1-11.... maybe that will speed up its operation since I doesnt have the other 3 to have to deal with.. dont know.

I did notice my little app called wifianalyzer scans all 14... I figured something as such.... thanks for being so helpful!

 

[phildroid]

No quixand is right about WiFi, you would have to have it TURNED ON for it to connect. It doesn't magically turn on just because a network is in range. I am sitting next to my D-Link and my DROID is in my hand......nope it definitely isn't "prioritizing" WiFi over 3G.

And for the 5GB cap, I had a heated debate about this a few weeks ago and turned out to be wrong. Read EVERY TOC/TOS on VZW's site and you will see they don't mention ANY 5GB cap, or any cap for that matter, for either the Email and Web for Smartphone or Unlimited Data. Now if you used a massive amount of GB every month they could flag you, but, they don't have any cap mentioned on any legal documents.

Actually there is a 5 GB cap on VZW plan. If you read your contract, ya know, the one that you signed, it specifically states that if you do anything to hurt VZW network, such as constant media streaming or the use of over 5 GB of data in a single month, your service may be terminated without notice.

 

[brettlewis]

If you call or go to the stgore in person, or have read through any of the other forums you would know the 5gb cap is ONLY for wireless cards, such as the one I own which allows me to use verizon 3g on my laptop. Your unlimited data plan IS unlimited. However, if you use your phone to tehter it will have the 5gb cap, but it will be seperate from your phone use and plan.

 

[phildroid]

Could you post said contract for our records?

Quoted from an article. Sorry. Won't let me post urls. On phone.

Back in August of 2006 I wrote about a guy who had his unlimited Verizon EVDO Wireless Data Service canceled unlimited Verizon EVDO Wireless Data Service canceled because buried deep into the Terms of Service (TOS) they mentioned some things that were unacceptable. Some of these things included downloading/streaming Some of these things included downloading/streaming music and videos

 

[brettlewis]

1. They did not have the same data plans in 2006 as they do now, I have had to change data plans during a conversion. edit: this current data plan was instated 04/14/2008, from the press release date on the news website.
2. Call and ask ANY store staff or tech support and they will tell you that is not true, I have called three different times, two of the times they asked If i read that in a forum, cuase thats where rumors like that start.
3. I still think your are confusing unlimited wireless and tethering/3g cards, like most people are. edit: the plan with the 5gb cap is called the "Mobile Broadband Plans for USB Modems, PC Cards, ExpressCards, MiFi™ 2200, Notebooks or Netbooks"

 

[windstrings]

It all about how you interpret the reading.

The term "unlimited" means if you abide by their terms of service.

What does that mean?

They have written "protections" in to prevent people from exploiting thier bandwidth... especially for share or for profit.

I'm sure if you go over 5mb and they investigate your usage and they see you are downloading, browsing... basically utilizing their services you are fine.

If they see you are tethering, then it gives them easy enforcement for bringing it to a stop.
I personally don't think they even care about tethering if its very occasional for email checking and "reasonable use"... but people who abuse a service ruin it for everybody else.

They use the term "unlimited" with an expectation of what normal and reasonable bandwidth use will be by a given customer.

At work, they allow you to use the internet and give you no limits on how much you can use... thats because they have an "expectation" of what your reasonable use will be.... however if you download continuous movies and music and video streaming and steal all the bandwidth so the rest of the company cannot function smoothly, then it becomes an issue of one person causing the whole to suffer.

In that case, I'm sure your "unlimited" use would no long be "unlimited" since you just redefined what your expected use is.

I don't think Verizon is headhunting and really does want us to have a pleasurable phone/pda experience.

I guess we could get mad that we can't tether and add access points and repeaters and feed the whole neighborhood and start a mini internet service and collect a fee since we have the right to "unlimited" service?

 

[phildroid]

1. They did not have the same data plans in 2006 as they do now, I have had to change data plans during a conversion. edit: this current data plan was instated 04/14/2008, from the press release date on the news website.
2. Call and ask ANY store staff or tech support and they will tell you that is not true, I have called three different times, two of the times they asked If i read that in a forum, cuase thats where rumors like that start.
3. I still think your are confusing unlimited wireless and tethering/3g cards, like most people are.

For the record, I am not confused about wireless vs tendering/ 3G cards. I use pda net to tether so I don't have to pay 30 bucks to have a 5 GB cap put on my usage. If you read the article, it says "back in 2006" meaning it was written at a later date. This Is just the research I've found.

 

[brettlewis]

For the record, I am not confused about wireless vs tendering/ 3G cards. I use pda net to tether so I don't have to pay 30 bucks to have a 5 GB cap put on my usage. If you read the article, it says "back in 2006" meaning it was written at a later date. This Is just the research I've found.

ok, so then just call and ask the source I guess. I spent a few minutes browsing the contracts snippets on the website and found no such language in it, there was similar language in the mobile broadband plan, but even before you get into that contract it has bolded "5gb limit"

The unlimited data plan had no speak of limits or caps it, it did have allowed use to say they dont want you watching porn and such, but other that that, no data roof/cap.