On Tue, Sep 1, 2009 at 10:40 AM, Dave Cridland<[email protected]> wrote: >> >> With which phones did you test it and which type of network? I'm >> asking because we don't don't have the same experience, in particular >> with 3G phones. Our tests show that TCP with a keepalive is much >> better than UDP sockets, but there is still a noticeable reduction of >> battery life (for example with no traffic we are still waiting for >> symbian phone able to stay connected for more than 36h over edge, utms >> is worse; in comparison when idle battery lasts a week). > > I'd note that "with keepalive" makes all the difference. > > A TCP session with no data traffic on it has no packets sent or received, so > should be the same as having the packet data session live, but no > connections over it, at least in principle.
> If there are data packets going over, then that means actual transmissions, > which will inevitably cost much more. Well, with keepalives I meant a byte each 10-30 minutes, depending on the timeout imposed by the network and you can ignored it. This is the minimum traffic you can do, otherwise your connection is dropped. Indeed the problems are related to levels 1-2 of the network, and you can't do a lot about it: for example you can't control when you radio receiver is on listening for possible incoming packets an that makes you consume a lot also when there is no traffic. > > > There's also the structure and behaviour of the mobile operator's IP > network. Orange in the UK dramatically improved over the past few years, for > instance. I've no idea what they did, but they changed from dropping dormant > TCP sessions within a minute or two to keeping non-silent TCP sessions live > for several minutes while the handset was outside coverage. yep, that was I meant with the firmware of the cells, however, I repeat, it has much more to do about L1-L2 than L4 > So I'm quite willing to believe that on some networks, it's possible to use > no keepalives at all, and get really very good battery life out of the > handset. Yes, there are improvements as I've said, but so far the only phones which work more or less well with long time connections seem to be blackberries bye -- Fabio Forno, Ph.D. Bluendo srl http://www.bluendo.com jabber id: [email protected]
