About high battery usage of Cell Standby of Mi8 caused by TD-SCDMA searching


Sep 1, 2018
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#1
Hello everyone

the current xiaomi.eu for MI8 i am using have a high battery usage on Cell standby which is about the level of Screen usage.

I input *#*#4636#*#* on the dial found out the network had been set LTE/TD-SCDMA/UMTS.

Because there is no TD-SCDMA signal beside the mainland of China. Once it is in a area with poor LTE signal the phone will search the TD-SCDMA instead, and then to UMTS.

The step for TD-SCDMA signal is the cause for the high battery using of Cell Standby.

I hope the next release can fix the problem.

Thank you.
 
Sep 1, 2018
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#2
With my other phone HMNote4x the network type is Global/TD-SCDMA which is mean that the phone will search all the global signal(Lte, wcdma etc) first, then and the last to TD-SCDMA.
It is a good setting. No hight cell standby. I guess i can still using the phone even in China.

Thank you.
 
Likes: morfei1
Dec 13, 2018
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#3
+1

Came to the same realization yesterday. Miui isn't defaulting to the wrong network modes on global devices causing high cell standby drain.

I can also ich confirm that setting it to lte/wcdma increases battery life.
Please confirm it here if you're affected:

http://en.miui.com/thread-4953373-1-1.html


There was even a flashable zip for redmi 4 with a modded system apk posted on the miui forums.
Then the miui settings of lte preferred / 3g / GSM only will default to the correct network modes for non China regions
https://en.miui.com/thread-1987637-1-1.html

Would be cool if xiaomi.eu could incorporate or adapt this?
 
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Likes: arboria
Dec 13, 2018
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#4
With my other phone HMNote4x the network type is Global/TD-SCDMA which is mean that the phone will search all the global signal(Lte, wcdma etc) first, then and the last to TD-SCDMA.
It is a good setting. No hight cell standby. I guess i can still using the phone even in China.

Thank you.

Mhm my redmi note 4x running xiaomi.eu 9.5(the last miui 9 release that still supports the gcam mod) is also defaulting to lte/td-scdma/umts.
 
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Dec 13, 2018
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#6
*bump*
Since this issue seems to to be be affecting a lot of of users and is somehow amplified since Android pie release on the MI8 - any chance xiaomi.eu team could incorporate this mod to teleservices.apk?

https://en.miui.com/thread-1987637-1-1.html

Guide to modifying teleservices.apk:
http://en.miui.com/thread-538223-1-1.html

It fixes the the miui network mode's to values that work better in western world / eu
 
Dec 13, 2018
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#7
Little followup on this.

I ran a test yesterday to find out if other devices handle it better and it does appear to be so. Mido battery drain with LTE/WCDMA and LTE/TD-SCDMA/UMTS was exactly the same.


But the cell signal history wasn't...

Redmi Note 4X, Xiaomi.eu 9.5, 70km Highway drive with Waze and internet music stream running, fixed display brightness. Same route in both tests, just opposite directions - hence me flipping 2nd signal history in the following screenshot:




So it looks like this isn't a general MIUI issue but rather a MI8 baseband issue...maybe being triggered or amplified by the network mode setting ?




We need more data on this - GreaseMonkey1960 requested a "Network Signal Guru" trace file but the app requires root and my MI bootloader is still locked:
https://xiaomi.eu/community/threads/9-1-1-2-3.48509/post-466488

So if anyone has a MI 8 and root could run a little test...drive along a specific route for an hour or so, have navigation and a video/music stream and a network signal guru trace running and then post results ?
 
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Likes: arboria
Dec 13, 2018
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#9
Well looks like xiami.eu team heard our prayers and adopted a different network mode with 9.1.10 weekly AND the ability to make it stick after a reboot.
Thanks - looking foward to flashing it once bootloader is unlocked. :cool:
 
Jan 4, 2019
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#10
Hello. Flashed 9.1.10 and LTE/UMTS sticks after reboot.
However, cell standby battery drain is the same, about 1% per hour. 7 hours idle, 7% discharge. Cell connectivity is always 6.6mAh per hour, idle and using. Wifi is 0.89 mAh per hour comparatively.

Mi A1, stock pie and locked, not tweaked, in 7 hours idle discharged only 1%, 0.2% per hour. Cell Connectivity was 1mAh per hour, idle and always. Six times less. What's the explanation?
 
Dec 13, 2018
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#11
Can't comment because I currently don't have to time to run a full comparison test again, but yeah at this point it might be more about improving network handover and connectivit than fixing "cell standby drain" :)
 
Dec 2, 2017
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#12
Can't comment because I currently don't have to time to run a full comparison test again, but yeah at this point it might be more about improving network handover and connectivit than fixing "cell standby drain" :)
Well, I've never looked at this before, but in my Max1 the "cell standby" ate 6% in 5 hours without having any sim card in the phone.

That seems to be slightly more than it ate in the Mix1 with two sim cards both active.

This might be like comparing apples & oranges, in different devices.

I've had more serious problems with a few apps, most recently the gallery app decided to keep the phone awake all night and ate most of the battery, so I had to finally "fix" it.
 
Dec 2, 2017
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#14
Yes, just looking at the % without any context is completely pointless - I agree.
Yes, the screen used 5 times as much in both, in sporadic daytime use.

I'll try a overnight test on mine, with and without the new setting.
With no screen time things should be comparable.

Perhaps I should turn off the cell radio in my Max1 while it has no simcard?
Hadn't thought of that.
 
Jan 4, 2019
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#15
Radio may be on even without simcard because of emergency call and that, and could search for more cell towers than having a simcard...
Handover in theory is fixed with 9.1.10 LTE>UMTS auto. No more chinese TC-CDMA.
 
Dec 2, 2017
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#16
Yes, the screen used 5 times as much in both, in sporadic daytime use.

I'll try a overnight test on mine, with and without the new setting.
With no screen time things should be comparable.

Perhaps I should turn off the cell radio in my Max1 while it has no simcard?
Hadn't thought of that.
I ran a comparative test overnight 12 hours with screen off and in "battery save" mode on my Mix1 with the new setting and my Mi Note 2 with the old setting.

Yes, it seems that the new settings do save about 1/3 of the cell radio battery usage, which is about 1.1% per day battery drain saved.
Which is nice, but on my Note 2 the cell radio only drains the battery about 3.6% per day with the old setting, not a big problem as it was.

I'll get back with how I calculated this figure if someone is interested, it would be a rather long post.
I do have a higher education in math and a lot of experience with statistics previously in life.

Mix1 and MI Note 2 are of course not exactly the same devices, but mine are set up exactly the same, have simcards using the same operator, have the same soc, and are in general quite similar, tend to have the same problems, etc.
 
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Dec 13, 2018
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#17
Experienced my first GSM/2G fallback today on global beta 9.1.10. Worked on both LTE/UMTS auto (PRL) and the default MIUI setting of LTE/TD-SCDMA/GSM.

Is anyone still on 8.12.20 and could post the baseband and kernel version ?
 
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Dec 1, 2018
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#18
Experienced my first GSM/2G fallback today on global beta 9.1.10. Worked on both LTE/UMTS auto (PRL) and the default MIUI setting of LTE/TD-SCDMA/GSM.

Is anyone still on 8.12.20 and could post the baseband and kernel version ?
Hi!

I'm just wondering, how did you fix this cell standby issue? What baseband or rom to flash and what settings should be used? I'm on EU dipper. Thanks!

Sent from my MI 8 using Tapatalk
 
Dec 13, 2018
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#21
No idea, but I'm certainly not going to start messing around flashing differing basebands...

Feel free to find out, test it and report your findings. ;)
 
Jan 4, 2019
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#22
I have thought about that too. But kernel needs compatible baseband image. You can't flash Pie rom/kernel and Oreo baseband. THEY must fix current baseband. Image for baseband is in rom formware and it is named 'modem.img'. It has the logic for baseband. It is out of the kernel.

I haven't done it myself and I don't know if TWRP will let you, since firmware lies in hidden partitions. It is potentially dangerous.

LineageOS thead in xda includes a copy of a recent Global Developer firmware and vendor .zip TWRP flashable prior to flashing rom, which enables you to sync the baseband when you install their latest rom.
 
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