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Evo 4G LTE -> 3G issue?


bmoses
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good morning everyone! so i got a new EVO 4G LTE last week and so far have been loving it, huge improvement over the original EVO that i had before!

 

However i have been noticing a small issue with the 3G connection. Using the CDMA field test app to look at the signal strengths of both CDMA and EVDO i can tell for the most part that both voice and data are either connected to the same tower or not. What i have noticed is that when i'm driving or going form one area to another voice will quickly switch to a new tower when the signal gets to low from the tower it was connected to, however 3G seems to stay connected to the previous tower until it doesn't have signal anymore.

 

i've seen it get as low as -118db for signal strength and then it finally loses connection. Then when it does lose connection to the old tower it seems like it takes a little bit to finally connect to the tower that is closer. and if it happens to pickup a signal from the old tower before it switches to the new it will connect back to that one again!

 

Has anyone else noticed this on their phones? I have another week for my 14 days and i'm just trying to figure out if its just how the phone is or if mine is having an issue and i need to go exchange it.

 

Thanks!

 

PS i'm in a third round market so no 4G for me for awhile :(

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This happens all the time if you are actively using 3G data. Phone doesn't want to hand off an active data session it is actively using until it has to, especially streaming. I bet if you stopped using data for a moment, 3G would switch sites.

 

Robert via CM9 Kindle Fire using Forum Runner

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hmmmmmm when i was watching it while driving this morning i wasn't actively using data, unless something was going on in the background. Was just watching the signal numbers between CDMA and EVDO waiting for EVDO to switch over to the tower that CDMA was connected too. I will watch for that though and see if thats the case. thanks!

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Whilst watching for those data signals to switch please don't neglect watching for those traffic signals to switch or for one of your fellow drivers to lane switch.

 

Maybe Sprint should make a version of those "this is the text I was sending" ads. "This is the speed test I was running when I slammed into those kids crossing the street. Their parents didn't understand that their children are dead because I just had to check out my data connectivity. Now I just get 1x on the phone my cell-mate smuggled in."

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bmoses could be experiencing the EV-DO hashing issue that I describe in this paragraph of my recent article on The Wall:

 

Another benefit of rehashing to a different carrier channel is that you may be able to connect to a closer cell site. Because not all cell sites have the same number of deployed EV-DO carrier channels, carrier channel hashing is an imperfect process. To illustrate, the cell site (call it cell site "A") that I detailed above for this trial has three EV-DO carrier channels (F1, F2, F3), as duly noted. But the adjacent cell site to the north (call it cell site "B") has only two EV-DO carrier channels (F1, F2). A handset that hashes to F3 on cell site "A" will cling to carrier channel PCS 0175 even as it moves north well into the coverage area of cell site "B." Interference will not be a problem, as cell site "B" does not transmit PCS 0175, but signal strength (and data speeds) will diminish until cell site "A" drops below a network defined threshold, at which point the handset will handoff to cell site "B" and hash to PCS 0150. This can require substantial movement and/or time. So, if you always want the most crisp EV-DO handoffs, you can try to ensure that your handset always hashes to F1, the EV-DO carrier deployed on essentially every site in the market.

 

http://s4gru.com/index.php?/blog/1/entry-318-can-toggling-airplane-mode-actually-improve-your-3g-data-speeds/

 

AJ

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bmoses could be experiencing the EV-DO hashing issue that I describe in this paragraph of my recent article on The Wall:

 

 

 

http://s4gru.com/ind...3g-data-speeds/

 

AJ

 

AJ i bet that is it, thanks! and i'm guessing that the original EVO didn't have this issue as much since it didn't have two antennas for SVDO, so whenever CDMA switched then EVDO switched?

 

and don't worry, was in an area with no traffic and no pedestrians, was on a mile long bridge going across a lake :)

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AJ i bet that is it, thanks! and i'm guessing that the original EVO didn't have this issue as much since it didn't have two antennas for SVDO, so whenever CDMA switched then EVDO switched?

 

I doubt that SVDO capability is related because even non SVDO handsets track CDMA1X and EV-DO PNs separately. While idle, non SVDO handsets just alternate back and forth between monitoring CDMA1X and EV-DO.

 

Does the idle EV-DO delay in switching PNs happen with every site all the time? If so, then you may have a defective handset. But if it happens with only some sites some of the time, then I would put my money on the EV-DO channel hashing lag that I detailed in the article.

 

AJ

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