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APNS always works over cellular data, even if you are connected to WiFi (because WiFi uses extra power, and thus iOS devices turn it off during sleep, without affecting APNS).

Is GCM (Google Cloud Messaging) capable of doing the same thing?

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cnst
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  • Related: http://android.stackexchange.com/questions/61554/is-there-a-way-for-3g-to-not-disconnect-when-connecting-to-wifi – cnst Jan 23 '14 at 01:14
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    It seems as though you've posted multiple valid questions about GCM. Have you taken the time to read over Google's developer documentation on the subject? You might find it beneficial. – Mr. Buster Jan 23 '14 at 01:56
  • @Mr.Buster, thank you for your suggestion. Since you agree that my questions are valid, may I ask why they are not being voted up at all? – cnst Jan 23 '14 at 02:03
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    Just a note aside : I always read (and my tests confirm) that it is data that consume more power than WiFi, especially when sleeping... – Matthieu Harlé Jan 23 '14 at 10:56
  • @Shywim, could you give more details? The rationale of data consuming less than WiFi is that GSM or UMTS radio is already required to be turned on in order to receive voice calls, thus it's not supposed to be consuming any extra power, compared to WiFi, which could be completely turned off during the sleep. Remember, we're also talking about a single persistent TCP connection here, not transmitting lots of data over WiFi vs. the cellular data connection. – cnst Jan 23 '14 at 17:22
  • @cnst: Only GSM is required to receive voice call, not mobile data (EDGE and up). It's true that there's always Cell Standby usage, but having mobile data enabled (and not wifi) uses more power as the phone search for the best network protocol (LTE>HSPA>UMTS>EDGE>none (GSM functions only)) and the best antenna available. When Mobile Data is not activated (or when WiFi is connected), Android search only for an antenna and that's all. So it may answer your principal question : GCM works also on WiFi (and I would say that it would be dumb, think of the tablets without sim). – Matthieu Harlé Jan 23 '14 at 17:31
  • APNS also works on WiFi. I'm not familiar with what the procedure for phones that support LTE is, and I do agree that a simple look at the datasheets would indicate that WiFi is more power efficient at data transmission compared to LTE; however, in the case of GSM/EDGE and HSPA, it is my belief that a single network connection is used for data and voice, thus there is no need to power on any extra radios for data compared to WiFi. Indeed, this may not be the case with LTE, as, I presume, you might still have to have either UMTS or GSM for voice capabilities. – cnst Jan 23 '14 at 17:40
  • @Shywim I decided to ask over at AskDifferent what does iOS do in the presence of LTE in regards to APNS: http://apple.stackexchange.com/questions/118421/does-apns-work-over-lte-or-only-umts-gsm-and-wifi If I had to guess, it'd be that it turns off both WiFi and LTE during sleep. – cnst Jan 23 '14 at 18:10
  • @Shywim, I found formal proof (in a book) that you're wrong. http://chimera.labs.oreilly.com/books/1230000000545/ch07.html#MOBILE_POWER_REQUIREMENTS In practice, when transferring large amounts of data, WiFi is often far more efficient if the signal strength is good. But if the device is mostly idle, then the 3G/4G radio is more effective. For best performance, ideally we would want dynamic switching between the different connection types. – cnst Feb 16 '14 at 22:30

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