Network based and a-gps, data use tests

Question

i was trying to find this kind of info, but only found others asking.
i hope this is useful info for others, especially while roaming.
skip to the bottom for conclusion,
this is the process i took:
i called nokia tech support,
their phone support his horrible,
the people on the phone don't actually know anything, and have to look up everything you ask them.
they were the worst.
i emailed nokia tech support.
my message was:
"i would like to know the difference between assisted gps positioning, and network based positioning. these are 2 of the 4 options on my nokia e66 for positioning methods. i would like to know if network based positioning uses internet data from my service provider to obtain my gps position. i am especially concerned with this function while i'm roaming internationally, as i do not want to be charged for roaming data use."
in about half hour they responded w/ an answer, and then 45 min after that someone else responded w/ an answer.
the first response, minus the hello's etc. was:
"In response to your email, Assisted GPS and Network Based positioning methods generate costs related to data traffic so you will be charged for data use. Only "normal" GPS and Bluetooth GPS do not generate additional costs related to data traffic.
Normal GPS is quite slow and does not work indoors. Therefore, it is recommended to enable at least A-GPS to get a faster position outdoors.
Network based and Wi-Fi positioning also allow you to update your position inside buildings, but they cannot be used for navigation."
the 2nd response was:
"In response to your inquiry, the difference between Assisted GPS positioning (A-GPS) and Network based positioning is that,  A-GPS uses satellites while Network based positioning is based on information of your cellular network environment. It allows you to update your position inside buildings, but they cannot be used for navigation. Both positioning methods generate costs related to data traffic (unless you have configured the device to use Wi-Fi connection to make the internet connection). The cost may vary while you are on roaming. Kindly contact the service provider for information about data transmission costs."
i can also respond w/ more questions, but instead did some tests, starting with sitting home, indoors, and eventualy moving to a window w/ lots of sky.
test 1:
i enabled:
integrated gps
network based
assisted gps
opened maps,
set maps to be offline,
set default internet access point to my home wlan network,
closed maps,
cleared all counters and the log on the phone's communication log.
opened maps
there is a pink circle around the area i may be in,
the icon that would show gps satellite strength, changes to show the cell phone antenna icon.
but the packet data counter is sending/receiving a total of around 3-8kb immediately, and over the course of time, it keeps adding up, every 1-2 minutes, and it is shown as packet data to/from the access point "at&t internet"
over the course of ten minutes, it's been about 43kb.
and i can tell on the phone's home screen that the packet data connection becomes active when it does.
the maps kb indicator still says 0.0kb, with a line through the double arrow packet data symbol.
test 2:
now i exited maps,
cleared the counters and logs
i turned off a-gps.
enabled only integrated gps and network based.
i open maps,
the same thing is happening as with the assisted gps on, except i connected to my home wlan once, in the middle of connecting to at&t internet 10 or so times.
everything else is happening the same.
test 3:
i exited maps,
cleared the counters and logs.
enabled only integrated gps.
i open maps, and there is no evidence of packet data connection, or wlan connection.
nothing is showing up in the logs or packet counters, and there is no pink circle around where i may be.
if i set maps to go online, w/ my wlan as the access point, or at&t internet, their respective icons show up on maps, as well as the phone's home screen.
the phone's log show respective connections are made but w/ 0.0kb, and the phone's packet counter, as well as the maps kb usage, say 0.0kb.
test 4:
set maps to offline, w/ my wlan as access point.
exited maps,
turned phone off for a bit to test gps from cold start.
turned on phone,
cleared counters/logs,
enabled only assisted gps and integrated gps.
open maps, there's no pink circle around where i may be, just the red dot of where it thought i last was.
there's about 4-5kb of data transfer,
then i bring the phone to the window where there's a lot of clear sky, and my location is found pretty fast.
i know that w/o assisted gps, w/ only integrated gps, it takes a while to get the gps signals.
i went back and forth to/from the window, and there was packet data use again only once more, not continuously like w/ network based positioning.
so to conclude my tests,
setting the maps to be offline, still uses a-gps and network based positioning.
network based uses a more data, continuously,
which is the opposite of what i thought, i thought a-gps would use more, so i was using network based on and a-gps off while in canada. whoops.
using assisted gps uses about 5-10kb, which, when roaming, according to at&t, they charge 1.95cents/kb.
might be worthwhile for getting a quick gps signal, nothing worse than waiting forever for it to connect.
the only way to be completely clear of data use is disable network based and assisted gps, or set the phone to offline mode.

Answer 1

A-GPS: This uses information from cell network to get a rough idea of where you are. It then uses this information to figure out which satellites to look for. Result is a faster satellite lock. So A-GPS uses a few kB of data to get an initial position, but navigation is done using GPS satellites, which does not require ANY data connection.
Network based: This uses information from the cell network to plot the current position when GPS satellite signal is not available, ie indoors, in a tunnel, etc. Position info derived from the cell network is not as accurate as that from GPS satellites, but serves as a stopgap until GPS signal can be re-acquired. Network based positioning used your data connection EACH TIME the satellite lock is lost. So the amount of data used is dependent on the quality of access you have to the GPS satellites. If you don't lose the connection to the GPS satellites, then you won't use any data.
The ‘offline’ option within the Nokia Maps app only refers to street, POI, etc searches, NOT to A-GPS, Network based positioning or to connecting with the GPS satellites.
If you want to navigate without using ANY data connection, set A-GPS off AND set Network based positioning off AND set the Internet option in Nokia Maps to Offline. Do this and you will not use any of your data connection allowance when navigating. There is no need to put the phone into flight mode.
If I've helped you, you can thank me by clicking the green 'kudos' star on my post. Cheers.