Problems programming Android signal-strength reporting for LTE

[lordsutch]

Cool. I got an email report from someone with a Samsung S3 where the v17 API doesn't seem to be reporting anything. That may have been a bug at my end; I'd be curious if it works now. I drove around a bit in some LTE areas and was able to fix a few buglets while I was out on the road (rapid application development in the car, always fun).

 

I also added a new feature (which should work on any Jelly Bean CDMA phone): a second log, "esmrcells.csv", now logs your location, SID/NID/BSID, and 1x signal strength when connected to a 224xx SID. Might help people with finding live ESMR cells. I probably can tweak the app a little to actually run OK on ICS too, for people that are interested in doing some ESMR tracking.

[digiblur]

Checked it out on LTE today on the Note2 (4.1.1). Doesn't show anything at all for LTE.

[lordsutch]

Bummer. Guess I'll need to poke around dexdumps of the Samsung field test apk some more.

[lordsutch]

I've hit a bit of a brick wall; apparently on Samsung devices the cell ID and physical cell ID are only available via an internal API that can only be called from the dialer.

 

However, I did figure out how to get the RSRP on most LTE devices, so that should now show up in the app at least. Hopefully when 4.2 hits the Samsung devices they'll implement the official APIs.

 

Edit: The last few releases were refusing to actually stop, and thus eating a lot of battery. If you downloaded in the last 48 hours or so, be sure to update to the latest apk.

[tommym65]

I've hit a bit of a brick wall; apparently on Samsung devices the cell ID and physical cell ID are only available via an internal API that can only be called from the dialer.

 

However, I did figure out how to get the RSRP on most LTE devices, so that should now show up in the app at least. Hopefully when 4.2 hits the Samsung devices they'll implement the official APIs.

 

The latest update does correctly show the LTE RSRP on my GS3. Thanks for all your effort.

 

Question: Is there a dialer code that allows you to see the Cell ID on the GS3? ##debug# will get me to "LTE Enginerring" (at least that's how Samsung spells it), but only the physical cell ID shows up there, and I'm having a hell of a time trying to sort through the values as I try to identify my local LTE cells, as the local offsets don't seem to be exactly 169. My understanding is that the Cell ID shows the cell in the first 5 or 6 hex digits, with the sector value in the last digit or 2. This would be much easier to track than the phys cell ID, but I can't find anywhere that it is reported in the GS3.

[lordsutch]

As far as I've heard, the iPhone 5 is the only device that shows both IDs on its debug screen. Both should be exposed by the CellIdentityLte API in Android 4.2, although that relies on the OEM's radio reporting the data.

[mikejeep]

Yesterday I updated my app to include an attempt at getting information from the API 17 functions as well.. if anyone wants to give it a try, the free version is "SignalCheck Lite" on Google Play. You don't need the paid version to see LTE cell info, just a device running Android 4.2 or newer.

 

lordsutch, how are your efforts panning out? I'm still running ICS on my EVO so I've never seen your app (or the LTE cell ID functions of my own app). I want to upgrade, but I prefer the Sense UI and haven't found a Jelly Bean version that doesn't feel like a downgrade.

 

I understand that LTE is the newest widespread cellular technology, but I still find it odd (and a bit frustrating) that this information is so difficult to get our hands on.. although the API 17 code is a big step in the right direction, even if it isn't widely supported yet.

 

-Mike

[lordsutch]

For the EVO, getting the Hex Cell ID requires a call to the "HTC Telephony Manager" service. Here's a rough outline:

 

private Object mHTCManager;
/* somewhere in onCreate() */
mHTCManager = getSystemService("htctelephony");
/* when you want to get the cell ID */
String cellID = "";
if(mHTCManager != null) {
Method m = null;
try {
 m = mHTCManager.getClass().getMethod("getSectorId", int.class);
 cellID = (String) m.invoke(mHTCManager, new Object[] {Integer.valueOf(1)} );
} catch (NoSuchMethodException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
} catch (IllegalArgumentException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
} catch (IllegalAccessException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
} catch (InvocationTargetException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
}
}

 

Unlike CellIdentityLte.getCi(), this will give you a String with the hexadecimal cell ID, not an integer. So you will probably want to do use Integer.valueOf(cellID, 16) to convert to an integer (or convert getCi()'s output to hex using String.format or something) in mixed code.

 

Full working code in GitHub at https://github.com/lordsutch/Signal-Strength-Detector/blob/master/src/com/lordsutch/android/signaldetector/SignalDetectorService.java

[lordsutch]

After watching the radio log on my EVO LTE today, it appears the Qualcomm RIL used by AOSP reports the LTE Cell Identity as if it was the UMTS CID, and it reports something else (probably the TAC/tracking area code; looking at pastebins it's too big to be the PCI/physical cell ID, alas) as if it was the UMTS LAC.

 

The bad news is that the internal telephony code in AOSP doesn't report this info via any exposed APIs. The good news is that it shouldn't be hard to hack the reporting into the existing code, although getting it accepted into CM may be a challenge.

[astorlavista]

I used to work for Ericsson / Ascom TEMS, devloping TEMS Pocket among other things, and my main problem with the Android cell info API:s is that there is no way to ask for the frequency (ARFCN/UARFCN/EARFCN) of cells.

 

Does anyone know why such an obvious value (to me at least) has been omitted from the API?

[mikejeep]

I used to work for Ericsson / Ascom TEMS, devloping TEMS Pocket among other things, and my main problem with the Android cell info API:s is that there is no way to ask for the frequency (ARFCN/UARFCN/EARFCN) of cells.

 

Does anyone know why such an obvious value (to me at least) has been omitted from the API?

As a developer, it drives me nuts as well. Would love to get a standard method to obtain frequency/band information, but it just doesn't exist. There is a suggestion in to have it added, but it's never been addressed. Seems like it should be a simple addition and it would be very useful for the apps a few of us on here have created.

 

-Mike

[astorlavista]

Where could i find this suggestion?

 

/kenneth

[mikejeep]

Where could i find this suggestion?

 

On the Android issue tracker.. I don't think it necessarily matters, but if more people 'star' this suggestion, perhaps Google and the AOSP folks will take note: https://code.google.com/p/android/issues/detail?id=54947

 

-Mike