Network Vision/LTE - Chicago Market

[Joeynach]

Maybe I'm not educated enough in this category, but how would turning things off cause all this interference?

I looked at my SNR more closely today.  Im sitting here with -81dbM LTE signal, but SNR literally 0, 0.2, 0.4.  It's the lowest I have ever seen, this can't be normal.  Is there something wrong with my device b/c I think we are talking about complete system failure at the point my phone is constantly pulling 0 SNR.  Something that no vendor would ever roll out with or let their consumer be exposed to....right?  Do you think if I took it in again Sprint reps would actually say something besides do a hard reset?

 

[tongboy]

A 1x RSSI of 56? Are you standing right in front of the antenna?

 

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[Vince]

What is a normal snr reading?

[Joeynach]

A 1x RSSI of 56? Are you standing right in front of the antenna?

 

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Yes, my office is literally 500 feet from a full NV tower, the green one (3G/800/4G).  I can see the tower out my window across the st on the building.  Which is why its so frustrating to have such strong signal and have such dial up ish speeds.

[Joeynach]

What is a normal snr reading?

I believe tongboy highlighted this earlier.  I found this in the "bars lie for LTE signal strength" article here on S4GRU.

 

Also another factor for good download speeds is the latency which determines the time taken to connect to the IP-Backhaul and backbone. The RSRP is good measure to find out the signal quantity but for signal quality SNR value needs to be accounted which shows a clean signal . below are the approx ranges for that metric

22 dbm-30dbm--- excellent

11dbm-22ddm--- decent

0dbm- 11 dbm--- bad

[tommym65]

I believe tongboy highlighted this earlier.  I found this in the "bars lie for LTE signal strength" article here on S4GRU.

 

Also another factor for good download speeds is the latency which determines the time taken to connect to the IP-Backhaul and backbone. The RSRP is good measure to find out the signal quantity but for signal quality SNR value needs to be accounted which shows a clean signal . below are the approx ranges for that metric

22 dbm-30dbm--- excellent

11dbm-22ddm--- decent

0dbm- 11 dbm--- bad

 

What is needed is for somebody to run a signal analyzer in the vicinity of a few Sprint sites in Chicagoland, to see whether there is some sort of obvious RF interference. (Where is AJ when we need him? Or rather, where we need him?)  Something is clearly out of whack.

[tongboy]

What is a normal snr reading?

There really isn't a normal reading. The higher the SNR the better off you usually are. Low SNR readings are fairly normal with a weak signal (rsrp of - 115 or so). Stronger signals (rsrp of -80) should have a very high SNR (20db or higher).

 

His snr and rsrp tell me he is seeing a very strong LTE signal but the phones radio is seeing it as almost all noise. That is very unusual.

 

 

[tongboy]

What is needed is for somebody to run a signal analyzer in the vicinity of a few Sprint sites in Chicagoland, to see whether there is some sort of obvious RF interference. (Where is AJ when we need him? Or rather, where we need him?) Something is clearly out of whack.

I agree with you. Something is really wrong. I'm not an expert by any means but I don't see how such a high rsrp can have such a low SNR and be a capacity issue. He is saying it is constant whereas capacity issues would get better late at night.

 

If I didn't have kids and a wife that wouldn't go nuts on the trip I would love a fox hunt and find out exactly what is going on.

[Joeynach]

There really isn't a normal reading. The higher the SNR the better off you usually are. Low SNR readings are fairly normal with a weak signal (rsrp of - 115 or so). Stronger signals (rsrp of -80) should have a very high SNR (20db or higher).

 

His snr and rsrp tell me he is seeing a very strong LTE signal but the phones radio is seeing it as almost all noise. That is very unusual.

That's what I am saying, something seems so amiss here there has to be something crazy going on.  And I don't believe its just isolated to a few cell sites in a few locations.  I was saying earlier my SNR can and is between 0-3 all the way on the brown line from Addison to the Loop, a 4 mile stretch, while my LTE signal is strong in the -80dbM to -95dbM range.  That would align further with the theory of the USCC site's interference vs. a small wireless network in some neighborhood is causing interference theory.  Right?

[Joeynach]

I agree with you. Something is really wrong. I'm not an expert by any means but I don't see how such a high rsrp can have such a low SNR and be a capacity issue. He is saying it is constant whereas capacity issues would get better late at night.

 

If I didn't have kids and a wife that wouldn't go nuts on the trip I would love a fox hunt and find out exactly what is going on.

Trust me its driving me crazy, and I asked my other friends with Sprint to verify they are seeing the same thing, one who lives in River North and the other in Lakeview.  It's not an isolated situation when you can span miles of differing Chicago neighborhoods there is a macro level systematic failure somewhere.

[tongboy]

That's what I am saying, something seems so amiss here there has to be something crazy going on. And I don't believe its just isolated to a few cell sites in a few locations. I was saying earlier my SNR can and is between 0-3 all the way on the brown line from Addison to the Loop, a 4 mile stretch, while my LTE signal is strong in the -80dbM to -95dbM range. That would align further with the theory of the USCC site's interference vs. a small wireless network in some neighborhood is causing interference theory. Right?

I'm not sure I buy the USCC interference. If they were to interfere Sprint would have to be using USCC band for LTE, which I haven't seen any signs of. If someone posts an LTE engineering screen we can see if Sprint is using a different band for LTE. In particular I would like to see what upload and download channel it is using.

 

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[Joeynach]

I'm not sure I buy the USCC interference. If they were to interfere Sprint would have to be using USCC band for LTE, which I haven't seen any signs of. If someone posts an LTE engineering screen we can see if Sprint is using a different band for LTE. In particular I would like to see what upload and download channel it is using.

 

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They mystery continues.

[Vince]

See, I think there are multiple issues. Interference AND capacity issues. I can download at 500kbps on a site at 7pm. Later in my shift, around 3-4am, I'll get ~2mbps, consistently, every night of the week. That would suggest come capacity problems. I can also drive 4 minutes from that slow area, and get 20mbps. So, I don't think it's completely market-wide. I think there are isolated trouble spots (possibly all the spots that share a location with USCC.)

[tongboy]

See, I think there are multiple issues. Interference AND capacity issues. I can download at 500kbps on a site at 7pm. Later in my shift, around 3-4am, I'll get ~2mbps, consistently, every night of the week. That would suggest come capacity problems. I can also drive 4 minutes from that slow area, and get 20mbps. So, I don't think it's completely market-wide. I think there are isolated trouble spots (possibly all the spots that share a location with USCC.)

That does sound like a textbook case of a capacity issue. Is your evdo speed acceptable?

 

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[Vince]

That does sound like a textbook case of a capacity issue. Is your evdo speed acceptable?

 

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In the bad spots, 3G is just as bad. Anytime I have a really good LTE speed, 3G can easily be a 2mbps/1mbps connection which is a great fallback.

[tongboy]

In the bad spots, 3G is just as bad. Anytime I have a really good LTE speed, 3G can easily be a 2mbps/1mbps connection which is a great fallback.

Ok. I understood the problem happening only on lte and fairly constant throughout the day/night. What you are describing is a classic capacity issue. Since it is happening on both evdo and lte it is probably a backhaul issue but it is hard to tell from the phone's airlink alone.

[JosefTor]

So, if this is a capacity issue, can it be fixed with turning on a couple more of those shiny fiber lines or is it a spectrum issue with little hope for a short term fix?

 

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[mhammett]

Capacity would have nothing to do with SNR.

 

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[tongboy]

Capacity would have nothing to do with SNR.

 

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I have seen times when limited backhaul can cause the SNR to fall with all the retransmits that take place. That was on Evdo. You are far more experienced with the rf side than I am so what would cause snr to fall in the PCS band during the day only?

 

[bucdenny]

So, if this is a capacity issue, can it be fixed with turning on a couple more of those shiny fiber lines or is it a spectrum issue with little hope for a short term fix?

 

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Not until all sites are live 4G with fiber back haul, we won't know if it is in fact a capacity issue with the back haul or the limited spectrum.

 

From my personal experience in San Diego, when a site does go live with 4G and a neighboring site is not live with 4G it does get congested. It will provide 4G coverage for a larger area until neighboring sites does go live.

[Vince]

Can a site be LTE active and not have an upgraded fiber backhaul? Maybe that would explain some terrible speeds. Or, maybe sprint isn't delivering as high of a speed line to the sites that they're leading us to believe.

[Joeynach]

Can a site be LTE active and not have an upgraded fiber backhaul? Maybe that would explain some terrible speeds. Or, maybe sprint isn't delivering as high of a speed line to the sites that they're leading us to believe.

I don't think so, I think Sprint must have the new backhaul in place in order to active the LTE site.  I think this is the reason those folks in Cyrstal Lake were talking about seeing the NV hardware in place for a year on their towers while they waited out the backhaul delay in Microwave towers before it finally went live.

[Joeynach]

I have seen times when limited backhaul can cause the SNR to fall with all the retransmits that take place. That was on Evdo. You are far more experienced with the rf side than I am so what would cause snr to fall in the PCS band during the day only?

It's not just during the day and whatever this systematic issue we have been speaking about is not just a Loop or city thing.  I went to the south suburbs on Sunday, drove from the Loop down i-57, and tested speed and LTE signal/SNR values the whole way.  Nothing good to report.  SNR was better, not in the 0-2 range, more in the 6-18 range, but speeds were awful.  I tested while on the road and while I was stationary in the South Burbs.  Was connected to strong LTE signals the whole time and never saw above 500K on either LTE or eHRPD.  Most of the LTE download speeds were between 200-400K consistently....on a Sunday evening in the burbs.  Yikes. 

 

Still can't figure it out, something just isn't right here.  It was just a couple months ago everywhere I went my LTE connection was pulling down 2, 5, 7, sometimes even 12MB/s download speeds, day or night, crowded city spots or not.  Its like it just gone.  I think the SNR values are certainly pointing us to the culprit, whatever that may be, but there is something amiss here at the macro level of Sprint's LTE network across the Chicago area.  I mean for Christ sake is 1:15am Monday morning, I'm sitting in my place in Lincoln Park, and thrilled to see a whopping 370K download speed (and 5.6 SNR) with LTE.  That ain't right!

[Vince]

I wish I could figure out how to see my snr on my iPhone. Can't seem to find it on the field test mode. I would love to give some input on this topic as well.

[jreuschl]

Sorry if this is a dumb question...  but what has changed on the retiring USCC network that it now has problems interfering with Sprint?  Did Sprint push a PRL update to USCC phones to share networks all of a sudden?