The quick fix enables tower assistance but that ins't the root cause of the problem. A GPS shouldn't need assistance from towers and should work from satelites alone.
GPS shouldn't DEPEND on network assistance to work, but having network assistance available will cut the time to get a fix by ~30 seconds or more. This is because two kinds of data are involved with GPS:
1) Telemetry data -- these are the signals broadcast by the satellites that basically say, "This is GPS satellite #27. It's exactly 8:47:29am on July 27th right... NOW!" If the receiver hears "...NOW" at 8:47:29.029, it knows the signal took 29 milliseconds to reach it, and based on the speed of light can calculate how many miles the signal traveled to get there.
2) Ephemera data -- these are signals broadcast by all of the satellites for 6 seconds every 30 seconds. This data tells the receiver, "Here's where all the satellites were at some point in time, and here's what their trajectories were".
In order to get a GPS lock, the receiver needs both sets of data. If it doesn't have current ephemera data available, it has to wait until a satellite broadcasts it, and it receives it without errors. That's going to take a bare minimum of 6 seconds under the most ideal conditions possible, and could easily take several minutes if all of the signals are poor. The only advantage to getting the data from a satellite is the fact that it spares you from needing network access at that instant. If you have network access anyway, you're better off just grabbing a copy over the network.
Also, the signal quality you need to download ephemera data is much higher than the signal quality you need to do a telemetry reading. So, if you can grab the ephemera data over the network, you're more likely to get a usable GPS reading indoors, and will almost certainly get one a lot faster.
I'm guessing that Samsung phones originally didn't use the network for ephemera data because HTC probably has a patent on it, or licensed it from someone who does. If Samsung phones do it now, that's good, because it means Samsung GPS will work better than it used to.
This is NOT "
aGPS". With aGPS, you're using the phone to grab the telemetry data, but using the tower to do the actual calculations.
In retrospect, aGPS is kind of a valuable service, even for phones that can do GPS entirely on their own. Why? GPS triangulation requires a LOT of floating point math, and floating point math requires a lot of battery power to do quickly. You CAN have a phone actively sniffing its location 24/7 so it can instantly respond to queries from apps, but you'll murder your battery within a matter of hours if you try. On the other hand, if aGPS is available, you can leave the GPS chipset powered up enough to sniff telemetry data, but save the power-consuming math and offload it to the tower.
As a practical matter, the time it takes to upload a few dozen bytes to a server at the tower, let it crunch the numbers against the ephemera data it already has in light of the fact that it already knows your approximate location (since tower location is fixed, and you're using that tower), and return a dozen bytes representing latitude and longitude is longer than it would take to determine your location if the phone were actively tracking it, but faster than it would take to do the calculation "cold" (if the phone were collecting data, but not doing the math until absolutely necessary).
Put another way, if Sprint charged 99c/month for "accelerated GPS" service, and you did stuff that needed to be location aware throughout the day without killing your battery, it would actually be a pretty valuable service worth getting. The problem is, the people setting the policies and pricing don't understand the underlying technical issues, and think their official navigation service offers enough value to someone to be worth several times that amount (it doesn't, because Google Maps can do the same thing for free). The line between "worthless" and "useful" is kind of blurry, and inhabits a big gray area whose exact details are largely determined by the cost of the service and the size of your battery.
