After understanding a bit about how actual cellular systems function, I realized that identifying the mobile/UE location is key in assigning the UE to correct base station and thus to guarantee a reliable network. For this , cellular systems make use of RSSI ( Received Signal Strength Indication) and assosciated statistics.But, in reality this is less useful due to the existence of Non LOS paths and other factors.

My question is why can't the UE share its GPS coordinates with the base stations thus easing the whole process?

  1. GPS is outside of operator's control.
  2. GPS signal is much weaker than cellular signal. You can get phone coverage in a concrete building (via windows) where you may not have the ability to receive GPS.
  3. Geographical position does not have to correspond to the physical signal path (unless in vacuum). Imagine that you are close to one base station in front of you. A big, metal bus appears in front of you and suddenly the "better" path is via a reflection to a base station behind you (and a handover occurs), yet you did not even move a meter.
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  • \$\begingroup\$ Thanks ! But a doubt: Many apps in a smartphone are accessing location details though they ask user for permission while installing. So, though it may not be in use now, isn't it possible that operator's can access GPS information if user ticks YES. \$\endgroup\$ – wanderer Sep 30 '18 at 20:34
  • \$\begingroup\$ @JyotishRobin Possibly, but where is the upside? You want a connection to the base station that is giving you the best signal, not necessarily the nearest base station. Consider a base station on top of a tall building, if you are stood at the base of such a structure you may have only a tiny signal from it (Antenna designs typically not radiating much power straight down, and there being a mess of concrete in the way), but quite a good signal to a similar one half a mile away. GPS will never capture that sort of nuance, measuring and doing handoff will deal well with that sort of thing. \$\endgroup\$ – Dan Mills Sep 30 '18 at 20:47
  • \$\begingroup\$ The mobile network operates far below the level of apps and user permission dialogs. The issues raised here are technical. The irony is that it usually works the other way around; approximate location and time information from the mobile network is used to make the GPS work better, by constraining its search of the possibility space and by ideally by giving it a local model of GPS error to unwind (civilian GPS with a local reference for GPS error from a base station in a known location is far more accurate than military GPS was designed to be) \$\endgroup\$ – Chris Stratton Sep 30 '18 at 20:48
  • \$\begingroup\$ @DanMills What I was trying to think is that if GPS info of a user location is available, say, broadcasted to all base stations, they based on the knowledge of geography of the area, the system can pick the best base station (best in terms of signal reach) and assign it to the user. \$\endgroup\$ – wanderer Sep 30 '18 at 21:13
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    \$\begingroup\$ But RSSI is what matters, not location! The cellular system really does not care about location. What matters is figuring out which base station has the best signal at the moment, in the situation that exists at present (I am in van with the physically nearest tower hidden by a ton of metal, I need the one that can see the phone thru the windscreen, but when I turn a corner that changes). GPS is Useless for this, you need RSSI (Actually what you really want is BER, but whatever). Now RSSI is hopeless for location for precisely the reason it is what you need for base station selection. \$\endgroup\$ – Dan Mills Oct 1 '18 at 11:47

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