I refer to the explanation I picked up from a pdf below. Please note a person who already has knowledge on A-GPS and CGEE and SGEE does not have to read the explanation provided for those below.
I know SGEE is downloading the Ephemeris information from the GPS Vendors server. Which I think is also scary in some aspects. (if anyone had any comments with regard to that kindly discuss)
My second Question is if a GPS is saving the used Ephemeris data in RAM and using the same in next startup. Is that called A-GPS or CGEE (Client generated EE)?
Explanation of Technologies
What is Assisted GPS? Assisted GPS or A-GPS uses some other communication channel such as WiFi or the mobile phone network to assist the GPS receiver by delivering current time and ephemeris data for all the satellites in the system. Having the current ephemeris data allows the receiver to be more precise in it’s searching, which makes the receiver sensitivity effectively the same as the tracking sensitivity. That is, it makes any start, a hot start. With A-GPS, the network provides the Ephemeris data to the GPS receiver to improve sensitivity the TTFF. Assisted GPS or A-GPS is also used to improve the performance within buildings where the GPS signals are by 20 dB or possibly more. Again by providing information to the GPS receiver in the mobile it is able to better correlate the signal being received from the satellite when the signal is low in strength. Using this technique it is possible to gain considerable increases in sensitivity under regular use-cases.
Client Generated Extended Ephemeris
Client Generated Extended Ephemeris (CGEE) is calculated on the client using broadcast ephemeris data downloaded for visible satellites. CGEE provides three day Extended Ephemeris (EE) models for visible satellites and stores the data in local memory. With CGEE no network connection is required.
Server Generated Extended Ephemeris
With Server Generated Extended Ephemeris (SGEE), a server obtains information from world-wide tracking stations and calculates the EE data for all GPS satellites at least once a day. To receive the data a network connection is required to download the data. Typical size for a one day payload to cover the entire constellation of satellites is around 11 Kbytes. These files are typically provided by the GPS supplier and are available to download at no charge.