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Excessive Adjacent channel interference?

briank101

By briank101
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briank101 Member Level: Digital

briank101

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There a particular stretch of roadway where my data speed drops to near zero everyday as I pass two competitor cell towers (50 yards to the left of me). If I'm listening to the 40 kbps streaming radio station I often listen to, it will be cutoff for about a minute. The Sprint EV-DO signal level is in the -90 dBm range (the nearest Sprint tower is about 1.5 miles away). It may happen in other areas but this is one that I can verify is consistent.

 

I would have thought with modern smartphone technology that the selectivity would be such as to prevent problems such as this and also that the beam tilt of the other provider towers would be such that they are not radiating too much power downwards. Or is it an adjacent 10 MHz wide LTE carrier one channel away from the Sprint 1.25 MHz EV-DO carrier the issue? Not sure if this affects voice calls as well as I have never been on a call at this spot, plus Sprint usually has me on the 1X800 band for voice anyway?

 

Has anyone else had this issue and is this something that we have to put up with when in the vicinity of any cell tower that is not our own provider? Not sure what the FCC adjacent channel interference guidelines are with this, considering this is not a 10,000 watt radio station but perhaps 10 watt signals at most at this particular suburban location.

 

PS. This is another reason why signal strength alone can be a bad indicator of potential data speed in addition to a host of other factors.

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tommym65 Member Level: eHRPD

tommym65

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There a particular stretch of roadway where my data speed drops to near zero everyday as I pass two competitor cell towers (50 yards to the left of me). If I'm listening to the 40 kbps streaming radio station I often listen to, it will be cutoff for about a minute. The Sprint EV-DO signal level is in the -90 dBm range (the nearest Sprint tower is about 1.5 miles away). It may happen in other areas but this is one that I can verify is consistent.

 

I would have thought with modern smartphone technology that the selectivity would be such as to prevent problems such as this and also that the beam tilt of the other provider towers would be such that they are not radiating too much power downwards. Or is it an adjacent 10 MHz wide LTE carrier one channel away from the Sprint 1.25 MHz EV-DO carrier the issue? Not sure if this affects voice calls as well as I have never been on a call at this spot, plus Sprint usually has me on the 1X800 band for voice anyway?

 

Has anyone else had this issue and is this something that we have to put up with when in the vicinity of any cell tower that is not our own provider? Not sure what the FCC adjacent channel interference guidelines are with this, considering this is not a 10,000 watt radio station but perhaps 10 watt signals at most at this particular suburban location.

 

PS. This is another reason why signal strength alone can be a bad indicator of potential data speed in addition to a host of other factors.

 

1. Are you receiving the music on LTE or EVDO?  2. If on LTE, have you looked at the LTE SNR value? There were rumors a few months ago about another provider interfering with Sprint LTE, and the supposed indicator was an outrageously poor signal-to-noise ratio.  The rumor was never verified, but look for SNR values near zero even in the presence good signal strength, which might indicate interference (or might indicate very heavy subscriber overloading).

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briank101 Member Level: Digital

briank101

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I'm using EVDO, and funny thing SNR stays in the 4 to 7 dB range (if I recall), I don't recall what the Ec/lo is though, I might make a note of this today. I'll try to remember to take a screenshot this evening when I pass there.

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briank101 Member Level: Digital

briank101

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Like clockwork the data dropped as I was passing the 2 "other cell company" towers on my way home yesterday.

Here's the SignalCheck screenshot. SNR was 7 dB so I don't know if that takes into account adj channel swamping. Now as I understand CDMA EV-DO has elements of spread spectrum technology so I would have just expected a data slow down, but bad enough to thwart a 40 kbps stream?..... not sure what's going on.

post-32078-0-09509800-1393428502_thumb.png

 

Here's a pic of one of the other company cell towers as I pass it.

post-32078-0-47398700-1393429014_thumb.jpg

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WiWavelength Member Level: LTE Advanced

WiWavelength

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This sounds like a failed handoff, not interference.  You may be looking at the other operators sites in search of a cause, but their presence is probably just coincidence.

 

AJ

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briank101 Member Level: Digital

briank101

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This sounds like a failed handoff, not interference.  You may be looking at the other operators sites in search of a cause, but their presence is probably just coincidence.

 

AJ

It's a consistent failed handoff though day after day and tracing back the BSID, it is connected to the correct sector on the nearest Sprint tower. I am in search of the cause and the other operator site was for me the first thing to suspect.

 

So if it is a bad handoff what would cause a consistent bad hand off?

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