Network location positioning

[boiker]

I've noticed that when I can't obtain a GPS satellite signal my network location is tremendously off -- usually .75 to 1.5 miles. Through location tracking on Google Latitude, Google has automatically determined that my house is located in the middle of a quarry almost a mile from my actual home. My work is located about 1.5 miles northeast of where I actually work.

 

While this is a somewhat minor issue, more and more smartphone apps are utilizing location to provide services. Weather, navigation, astronomical, and social services depend on accurate location information. Unless I have a clear view of the sky, I'm not going to have accurate location information.

 

I have observed this issue with the four different phones I've recently owned. Is this a Phoenix network issue? Is this a Sprint network issue?

 

Anecdotally, my brother's ATT iPhone was much more accurate than my phones with network based location.

[Contreramanjaro]

That seems decently accurate to me. I'm not all that sure how the whole system works but I'd imagine there is a lot of guess work and maybe some assumptions made based on the towers you can contact. I don't think there is any question that ATT has more towers than Sprint in most areas. May I ask why you don't just use GPS for your location which for me is accurate to something like 6 meters.

[S4GRU]

That seems decently accurate to me. I'm not all that sure how the whole system works but I'd imagine there is a lot of guess work and maybe some assumptions made based on the towers you can contact. I don't think there is any question that ATT has more towers than Sprint in most areas. May I ask why you don't just use GPS for your location which for me is accurate to something like 6 meters.

 

I can't go along with such a broad statement. In places where ATT is deployed on 850 and Sprint on 1900' date=' Sprint has more sites. But I think I understand what you are trying to say.

 

I've noticed that when I can't obtain a GPS satellite signal my network location is tremendously off -- usually .75 to 1.5 miles. Through location tracking on Google Latitude, Google has automatically determined that my house is located in the middle of a quarry almost a mile from my actual home. My work is located about 1.5 miles northeast of where I actually work.

 

While this is a somewhat minor issue, more and more smartphone apps are utilizing location to provide services. Weather, navigation, astronomical, and social services depend on accurate location information. Unless I have a clear view of the sky, I'm not going to have accurate location information.

 

I have observed this issue with the four different phones I've recently owned. Is this a Phoenix network issue? Is this a Sprint network issue?

 

Anecdotally, my brother's ATT iPhone was much more accurate than my phones with network based location.

 

If you have GPS issues on all devices, I'm leaning toward an issue with your geographic location. Are you near a LightSquared test site? Does the issue exist when you travel with all those devices?

 

I sometimes have problems with my E4GT locking on with some Custom ROM's I've used. But HTC products have been solid with GPS in my experiences. And I have more problems in larger cities (like when I go to ABQ) than I do in rural areas. The noise floor is much higher for your device.

 

GPS is based on your GPS radio in your device. Not your wireless carrier.

 

Robert - Posted from my E4GT with ICS using Forum Runner

[MacinJosh]

Robert, I've had problems with GPS in my Evo Shift since day one. Very hard to lock on to a satellite unless the phone is on the dash of the car.

[boiker]

GPS with my Evo is usually rock-solid. However, within buildings (like work) or steel structures the GPS won't lock and I rely on network positioning. My wife's Epic4G is terrible at locking GPS location indoors, acceptable outdoors. My Evo will often lock indoors when she can't and almost never fails outdoors.

 

Are you near a LightSquared test site?

 

I don't know where those are at.

 

Does the issue exist when you travel with all those devices?

 

I noticed when visiting Chicago and my GPS off, my network position was +-400-ft and tracked my speed and direction pretty well.

[S4GRU]

GPS with my Evo is usually rock-solid. However, within buildings (like work) or steel structures the GPS won't lock and I rely on network positioning. My wife's Epic4G is terrible at locking GPS location indoors, acceptable outdoors. My Evo will often lock indoors when she can't and almost never fails outdoors.

 

 

 

I don't know where those are at.

 

 

 

I noticed when visiting Chicago and my GPS off, my network position was +-400-ft and tracked my speed and direction pretty well.

 

Your brother has an AT&T device that works great indoors? I haven't had any device that is good with GPS inside most structures. Some will, some won't. Some maybe if you are near a window. If you just mean network based location, that makes sense. GSM devices stay in contact with many sites at once, allowing for much better triangulation. I also think that iPhone are better with GPS, in general, based on my experiences.

 

The signals from GPS satellites are pretty darn weak and don't penetrate very well at all. It's amazing that they even work in a car.

 

Robert

[4ringsnbr]

GSM devices stay in contact with many sites at once, allowing for much better triangulation.

 

I think you have that backwards. CDMA phones can (and do) connect to multiple towers/sectors all the time-- everybody talks on the same channel allowing soft handoff which is why CDMA calls practically never drop. GSM is a TDMA technology-- it CANNOT connect to more than one tower at a time as they're all on different channels from their neighbors and use different timeslots-- the hard handoff is why GSM is a very, very poor voice technology in comparison. Now GPRS/HSPA (3G "GSM") is W-CDMA, so it can connect to multiple towers.

[S4GRU]

I think you have that backwards. CDMA phones can (and do) connect to multiple towers/sectors all the time-- everybody talks on the same channel allowing soft handoff which is why CDMA calls practically never drop. GSM is a TDMA technology-- it CANNOT connect to more than one tower at a time as they're all on different channels from their neighbors and use different timeslots-- the hard handoff is why GSM is a very, very poor voice technology in comparison. Now GPRS/HSPA (3G "GSM") is W-CDMA, so it can connect to multiple towers.

 

I am using poor terminology. GSM stays in contact, but it does not allow for soft handoff. My agency used to use AT&T and I would use an app called Antennas (http://www.androidce...puts-bars-shame) on it. It would show all the GSM towers that my device was seeing. The device also used this same information and would triangulate your location when you used the network to determine location.

 

Since then, our agency has moved to Verizon. So now I have a CDMA personal and work phone. The CDMA devices I have used only show one location on Antennas app and when you use the network to determine location, they seem to be much less accurate. This is not because of the handoff technology (which obviously CDMA is far superior) but because of the number of sites the device is listening to and can get coordinates for.

 

I didn't mean to imply that the GSM devices are actually "connected" to these additional towers.

 

Robert

[4ringsnbr]

 

Since then, our agency has moved to Verizon. So now I have a CDMA personal and work phone. The CDMA devices I have used only show one location on Antennas app and when you use the network to determine location, they seem to be much less accurate. This is not because of the handoff technology (which obviously CDMA is far superior) but because of the number of sites the device is listening to and can get coordinates for.

 

 

Some of the difference in network location accuracy might be due to the timing signaling required by GSM. As a primitive TDMA technology, the timing signals and synchronization must be kept very tight between the towers and the handset so the system will work (timeslots cannot overlap). This is also why there is a strict 35 km limit to a cell size in GSM-- the timing signals keep the system working. Timing signals would help the triangulation done by any device. CDMA towers also sync to GPS time, but the CDMA technology does not rely on timeslots for 1x communication-- only PN timesync skew when syncing pilot channels.

[digiblur]

 

I am using poor terminology. GSM stays in contact, but it does not allow for soft handoff. My agency used to use AT&T and I would use an app called Antennas (http://www.androidce...puts-bars-shame) on it. It would show all the GSM towers that my device was seeing. The device also used this same information and would triangulate your location when you used the network to determine location.

 

Since then, our agency has moved to Verizon. So now I have a CDMA personal and work phone. The CDMA devices I have used only show one location on Antennas app and when you use the network to determine location, they seem to be much less accurate. This is not because of the handoff technology (which obviously CDMA is far superior) but because of the number of sites the device is listening to and can get coordinates for.

 

I didn't mean to imply that the GSM devices are actually "connected" to these additional towers.

 

Robert

 

Some older sprint phones used to show all the neighboring cells it could see. It seems all the latest phones do not show this anymore.

[4ringsnbr]

Some older sprint phones used to show all the neighboring cells it could see. It seems all the latest phones do not show this anymore.

 

If you look at the 1x or EVDO engineering debug screens, there should be a neighbor set and candidate set. If I recall, the candidate set is the PN of the other sectors the handset is seeing (with worse Ec/Io than the chosen pilot) and the neighbor set is either the handset's memory of the most recent sectors' PNs or a network-delivered list of neighboring PNs.