LTE affecting voice signal?

**sstea** · 07-24-2012, 09:41 AM

I am in the Atlanta area where Sprint has started to provide sporadic LTE service. Over the past few days I have noticed something strange. When I am in LTE/CDMA mode instead of CDMA only I seem to be getting weaker voice signal. I have noticed this more outdoors.

This is not conclusive, but I took one measurement. In a parking lot, in LTE mode with the 4G icon displayed, my phone was reporting a signal of only -111dBm. When I switched to CDMA only (requiring a clunky reboot) the signal strength was much better at -80dBm. I have noticed that when my phone is registering 4G the bars and reported signal strength are significantly lower than when I am only in CDMA mode.

Anybody else observe this?

**Almeuit** · 07-24-2012, 10:18 AM

I don't have LTE in my area but I can take a guess at what's happening.

I think what's going on is sprint has most places with 3G...such as Atlanta. So when you are in CDMA (3G) you will get a better signal since there is more coverage.

However when your on the LTE there is less signal strength since they have launched the network but are still putting up new sites constantly. So since there is less towers your getting less coverage.

I think this may be the answer. Correct me if I am wrong anyone.. I am pretty sure (or it makes sense in my mind) that when you're on LTE instead of CDMA the voice will go through LTE as well.

Sent from my SPH-L710 using Android Central Forums

**sstea** · 07-24-2012, 10:27 AM

Almeuit,

Thanks for your response, but I think you misunderstood my post. I am taking the measurements in the same exact spot. I am taking the readings with LTE enabled and LTE disabled. With LTE enabled I am seeing much lower signal readings (bars and reported dBm) from the same exact location.

**clavodulce16** · 07-24-2012, 11:26 AM

Perhaps the signal your reading is from the LTE tower. When 3G alone your might be connecting to a closer tower.

Make Sense ?

**boomerbubba** · 07-24-2012, 11:33 AM

Originally Posted by sstea

Almeuit,

Thanks for your response, but I think you misunderstood my post. I am taking the measurements in the same exact spot. I am taking the readings with LTE enabled and LTE disabled. With LTE enabled I am seeing much lower signal readings (bars and reported dBm) from the same exact location.

The dBm metrics are not simply comparable between CDMA and LTE. The units (dBm) are the same, but the thing being measured is different. CDMA reports signal strength calculated as RSSI; LTE reports its signal strength calculated as RSRP.

Here is a short.

**sstea** · 07-24-2012, 12:10 PM

Originally Posted by clavodulce16

Perhaps the signal your reading is from the LTE tower. When 3G alone your might be connecting to a closer tower.

Make Sense ?

That is possible. I was perhaps mistakenly assuming that the LTE data connectivity and the link to the tower for voice were independent. This means that the system may connect you to a more distant tower for LTE service at the expense of your voice signal and battery. I really wish they had a toggle (like with Wimax) to simply enable and disable LTE. It is not very user friendly to have to dig into 3 levels of settings menus and reboot your phone to turn it on or off.

**sstea** · 07-24-2012, 12:16 PM

Originally Posted by boomerbubba

The dBm metrics are not simply comparable between CDMA and LTE. The units (dBm) are the same, but the thing being measured is different. CDMA reports signal strength calculated as RSSI; LTE reports its signal strength calculated as RSRP.

Here is a short.

I am not sure that the dBm reading in the settings menu is specific to LTE or 3G EVDO as opposed to the general signal for voice. Do you know if this is the case? When I am in my house running on Wifi and a femto cell for voice the system reports a dBm measurement that seems to pertain to the strength of the voice signal.

**sstea** · 07-24-2012, 12:44 PM

Originally Posted by boomerbubba

The dBm metrics are not simply comparable between CDMA and LTE. The units (dBm) are the same, but the thing being measured is different. CDMA reports signal strength calculated as RSSI; LTE reports its signal strength calculated as RSRP.

Here is a short.

Good article. Thanks for the link. On the web page they showed a screen shot from a phone which specifies that the measurement is RSRP. On the Sprint GS3 it is only showing dBm generically. So maybe I am getting concerned over nothing... I am still confused as to voice vs data. Since they are interdependent, I was concerned that the voice signal strength was being degraded in LTE mode, but maybe the signal strength is specific to data...I don't know.

**boomerbubba** · 07-24-2012, 01:09 PM

Originally Posted by sstea

Good article. Thanks for the link. On the web page they showed a screen shot from a phone which specifies that the measurement is RSRP. On the Sprint GS3 it is only showing dBm generically. So maybe I am getting concerned over nothing... I am still confused as to voice vs data. Since they are interdependent, I was concerned that the voice signal strength was being degraded in LTE mode, but maybe the signal strength is specific to data...I don't know.

They are independent. Your voice connection is still CDMA. LTE is data only.

**sstea** · 07-24-2012, 01:57 PM

Originally Posted by boomerbubba

They are independent. Your voice connection is still CDMA. LTE is data only.

So when you go into settings and see the dBm reading is it pertaining to voice or data?

Thanks

**Almeuit** · 07-24-2012, 02:27 PM

Originally Posted by boomerbubba

They are independent. Your voice connection is still CDMA. LTE is data only.

Thanks. That's what I wasn't sure on

Sent from my SPH-L710 using Android Central Forums

**boomerbubba** · 07-24-2012, 02:29 PM

Originally Posted by sstea

So when you go into settings and see the dBm reading is it pertaining to voice or data?

I don't know firsthand, because I actually don't own a GS3 yet. (Waiting for Sprint's LTE rollout to reach my area.)

From what you report here, and secondhand reports from others, I am pretty sure that if you have an LTE connection then the Settings -> About ....screen would be reporting the RSRP for LTE as dBm. I know one extremely good analyst who is working on a signal-strength comparison test that is not yet published, and he says this is the only screen to get dBm reported for LTE. He is testing an HTC EVO LTE, a Sprint GS3 and a Galaxy Nexus.

Is there anything in the context of that screen on your phone that might resolve the ambiguity? (I think I have seen screenshots somewhere that make this explicit, but I may be recalling HTC EVO LTE screenshots. Most people in various forums just keep posting brainless SpeedTest screens.)

**sstea** · 07-24-2012, 04:18 PM

Originally Posted by boomerbubba

I don't know firsthand, because I actually don't own a GS3 yet. (Waiting for Sprint's LTE rollout to reach my area.)

From what you report here, and secondhand reports from others, I am pretty sure that if you have an LTE connection then the Settings -> About ....screen would be reporting the RSRP for LTE as dBm. I know one extremely good analyst who is working on a signal-strength comparison test that is not yet published, and he says this is the only screen to get dBm reported for LTE. He is testing an HTC EVO LTE, a Sprint GS3 and a Galaxy Nexus.

Is there anything in the context of that screen on your phone that might resolve the ambiguity? (I think I have seen screenshots somewhere that make this explicit, but I may be recalling HTC EVO LTE screenshots. Most people in various forums just keep posting brainless SpeedTest screens.)

I'll take a screen shot when I am in range of LTE next time. When I look at the signal strength it just shows dBm and a value for asu (not sure what asu stands for). It does also indicate mobile network type in a separate field.