well...take your time...you gonna need it to explain OFFLINE A-gps.....
I am new to linux....not to gps......
most if not all A-GPS implementation in mobile phones make use of pre-determined (through algorithm) orbit path of the satellites (otherwise known as ephemeris data) to triangulate the position. This information takes roughly 30sec per satellite to download if through directly from Satellite, although they can be received concurrently. However, every interruption of signal (block by buildings, tree canopy, etc) result in the whole transfer process repeated again. Today's A-GPS implementation, unlike the earlier days where assistance servers are used to offload the triangulation process, offer the availability of the ephemeris data in advance through internet, eliminating the potential delay in the triangular process. The added advantage is the data has a lifespan of 5-7 days, versus 4 hours if getting it directly from Satellite. The result is fewer 'cold start' situation but as the age of the downloaded ephemeris gets older, the accuracy of the triangulation process gets lower as well.
I am sure you know all these, or maybe have different opinions. But my point is you can still get a location fix with APN or WIFI turned off, because the ephemeris would have downloaded way before.
Otherwie, I agree that getting a fix in a farmland, even indoor, makes alot of difference as compared to getting a fix in a building/apartment.
PS: If we want to discuss this further, maybe a new thread is in order. I digress.