A 2G connection is shown to be less power hungry than 3G. Since the N900 is an 'always on' data device, using 2G as its main source of data for low data intense applications (email/widgets) would make sense. However if you wanted to say surf the internet/stream music, 2G is just too slow.

My idea is:

An application that keeps the the default GSM connection as 2G that then switches to a 'heavy data mode' (3g/wifi) when specified applications are opened (eg internet browser, spotify, internet radio etc). This would increase battery life considerably.

http://maemo.org/community/brainstor...battery_saver/

It sounds fairly easy to create too..

Great Idea!

I like it! Has anyone done any testing to figure out how much power it takes to initiate the connection and how much data downtime there is when switching?

Yep, would be interesting to see some figures for the consumption using 2G vs 3G and for the connection setup power costs.

Once those are available, this is the type of thing that might be useful for a program like e.g. Shepherd to be able to control.

Its indeed a very nice idea and Ive seen this saving atleast 30% of my battery on my t-mobile G1.

However AFAIK the phone would de-register and have to register again with the network when switching from 2G to 3G and vice versa. ( means a couple of sec delay/break ;-) )

I will try to find something more detailed on this.

Does anybody have more info ?

For background apps delay/latency is not a big deal. The only type of issue (that comes to mind) is when sticking with a 2G connection for a background task that needed a larger amount of bandwidth (ex. you received an email with attachments). Even then, if the email client was smart enough it could download message headers with 2G and attachments with 3G (but I don't know if you can "choose" which connection to use for what).

Anyway, it would seem like the easiest way to get started on this would be to toggle your connection based on the phones state: suspend only keeps 2G open but when you bring the phone out of suspense (turn on the screen), it goes ahead and initiates the 3G connection (if available). Go back into suspend then drop the 3G and fallback to 2G.

Well I proposed this some time ago:

Switch automatically to 3g only when browsing.

Thanks for the brainstorm entry though!

Could this be done based on the network traffic instead of the open applications? Something similar to what the kernel does for the CPU. I don't know how is going to work, but I plan to use the N900 without closing most applications so this approach wouldn't fit on my way of using the device.

this would need to turn off your 3G device, while in 3G mode, if you like to swap between gsm modes there will be a new negotiation.

what about real throttling? is the 3G device scalable? is it possible to prevent the 3G from powering up while no connection is available? My 3G eats the battery when I have my phone at dead spots in my apartment, there it cannot establish >2G services but GPRS is still working. So if you scale down the 3G by software and have an automatic fallback to another technology (EDGE, GPRS, you name it) you wouldnt need to negotiate because of switching the network mode to something without 3.xG (GSM+GPRS+2G+3G+3.5G -> GSM+GPRS+2G). This could also help if no 3.xG network is available to reduce the frequency the 3.xG device is trying to establish services.

so on the one hand it could be a program managing services and on the other it could be simple settings of the services. the last one I would prefer! Depending on what network requests are pending, Xsec timeout, if after that time the deamon is still touched with new requests, the device decides to powerup 3.xG if active in the current mode. Or it scales down if no intense requests are pending anymore.
comments, please

IMHO this is the best solution. Having the network connection pause when you first open a website would be damned annoying, and this should realize 99% of the power saving.

One addition, though: forcibly keep the indicator on 3G so that the user doesn't always get distracted by the icon changing a few seconds after the screen is activated.

The only downside I see is that users who constantly check their calendar would be draining their battery with reconnections. This could be solved with a minimum interval between successive switches to 2G.