Assisted GPS or Augmented GPS (often abbreviated as A-GPS or aGPS) is a system to help reduce the start-up and start-up time of a GPS device.
A-GPS is currently appearing commonly in phones, computers and tablets with GPS, especially the use is more and more after the US requires 911 calls (call police, call emergency) to be located. caller for assistance as quickly as possible.
Normal GPS devices only rely on information from satellites to function. They will take about 30-40 seconds to locate you on the first boot because the data rate of the satellite signal is only about 50 bits/s, which is very slow, making the download lose a lot of information. . That is not to mention if the satellite signal is lost while starting to locate, the device will have to redo this step from the beginning, and then in the urban area, the signal will also be weaker because of buildings, not to mention the weather conditions, meteorology and even tree cover.
How A-GPS works.
That’s why people make A-GPS, it will work thanks to the A-GPS servers deployed by mobile carriers. These servers can be considered as caches of GPS data, which will take data from satellites and store them in a database on the ground. When your phone accesses these servers, they get information much faster using 3G, 4G, even Wi-Fi connections. These connections are much faster than satellite links.
Thus, your phone will get information about its location in an approximate way, although not as accurate as getting data directly from GPS satellites, but still locate a narrow area in real time. Very short is already good. Slowly, as the GPS signal becomes more stable, the phone will calculate the exact location.
This supporting data is divided into 2 categories:
As you can see above, A-GPS requires the Internet to work , so when you go into a weak signal area or the network connection is interrupted, A-GPS no longer works. And in theory, you also need to spend a little bit of money on 3G and 4G network capacity, but not much. Meanwhile, the GPS connection is not dependent on the Internet at all.
Most phones today do not only use GPS or A-GPS, it also combines with Wi-Fi positioning systems, cell tower positioning systems to calculate your location. That’s why iOS and Android both show that when you turn on Wi-Fi, the location will be more accurate than when using only GPS.