Motorola Droid RAZR, RAZR MAXX Update Enables CDRX for Better LTE Battery Life
by Brian Klug on February 3, 2012 12:24 AM EST- Posted in
- Smartphones
- LTE
- Motorola
- Mobile
- Droid RAZR
- RAZR MAXX
- RAZR
While we don't usually cover every software update on every platform, I thought it worth noting something special about the new update which will begin going out shortly to the Motorola Droid RAZR and RAZR MAXX. Among the features included in "6.12.173.XT912.Verizon.en.US" is a new feature that isn't directly advertised in the changelog - it's the inclusion of Connected Discontinuous Reception, or CDRX for Motorola/TI's codename Wrigley 4G LTE baseband. The short of it is improved battery life on 4G LTE.
Discontinuous Reception (DRX) is nothing new for UMTS based networks, and is a power reduction feature. The aim is simple - during idle periods, the cellular network tells the handset that it doesn't need to expect any traffic, and thus the handset can shut down the RF frontend and other power draining bits. The phone can then wake up the parts required to receive and listen to a paging channel when the discontinuous cycle ends.
The above is the way things work in UMTS, in 4G LTE things change a bit, but the concept is the same. However a new feature is the somewhat strangely-named connected DRX mode. The "connected" part comes from the fact that DRX now can work while the user equipment is in an RRC_Connected state, in addition to RRC_Idle. The result is that the handset can now shut down parts required to listen with much finer frequency, for example during the idle periods when a webpage is loading, as opposed to the longer idle periods when the phone is locked and in a pocket.
I'm told that CDRX is now enabled on about half of Verizon Wireless' 4G LTE network, specifically in markets where Ericsson is the radio network equipment supplier. The other Alcatel-Lucent markets will be upgraded as well in due time. Unfortunately my markets in Tucson and Phoenix AZ are Alcatel-Lucent (to the best of my knowledge, from seeing many empty Alcatel-Lucent boxes and trucks around new LTE eNodeBs), so I'll have to wait to see just how big of a difference this makes in real-world testing.
Source: Verizon Software Update (PDF)
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Impulses - Friday, February 3, 2012 - link
It's pretty amazing how network conditions beyond signal strength can have an impact on battery life... Sigh, how I wish Verizon hadn't left Puerto Rico, we get every other US carrier except the one seemingly doing the best job of improving it's network. #pitypartyBrian Klug - Friday, February 3, 2012 - link
The nice thing is that enabling these features are as simple as pushing out a software update for Ericsson/Alcatel-Lucent, so the same should happen for AT&T (or maybe already has) and other LTE networks.-Brian
Souka - Saturday, February 4, 2012 - link
I really hope it happens on the AT&T network.... at my work we're turning in our iPhone3gs for Droid options. I like the Nitro or SG2-skyrocket, but co-workers are reporting the battery life SUCKS!No way to turn off the LTE other than to turn off data altogether which isn't a fix.
(I looked online....didn't see any LTE off option)
Brian Klug - Saturday, February 4, 2012 - link
You mean on the AT&T LTE devices? Try under *#*#4636#*#*, Phone Information, then the menu there. AT&T is removing options wherever possible to let you use 2G or 3G for obvious reasons - they want fewer people on those carriers so they can run fewer. There's usually a way to hop back down though if you look for it.There is truth to the fact that AT&T LTE devices are getting marginally better battery life too since they don't have another radio camping 1x all the time. It's either WCDMA or LTE (or GSM/EDGE) for the MDM9200 in those devices.
-Brian
name99 - Sunday, February 5, 2012 - link
These sorts of features are not specific to Verizon. If you look at the 3GPP roadmaps (they are not secret) you will see that there is constant modification to subtle issues (like the state machine governing how handsets transition between idle, more-or-less connected, and more-or-less transmitting/receiving data) to reduce power.These changes aren't as sexy as adding QAM64 (changing download max speed from 14 to 21Mbps) or spatial-multiplexing MIMO or (soon to come) wide (bonded) channels for UMTS, but they are part of each successive spec, release 8, release 9, and so on. And because they are part of the spec, they do get rolled out into everyone's equipment in time. VZW seem to be more aggressive than the other telcos in not allowing truly crappy radio equipment in their mobiles, and in rolling out (or at least publicizing rolling out) upgrades to their towers, but at the end of the day the differences across carriers are more like a year or so differences in precisely when something gets rolled out, not much more than that.
nyonya - Friday, February 3, 2012 - link
Is a similar update being pushed to the Droid Bionic? Or any other LTE phones?Brian Klug - Friday, February 3, 2012 - link
I would assume so given that the three share identical cellular architectures and basebands. I just don't know what version of the Bionic software/radio includes the update, so I can't say for sure.-Brian