gps - Why does google maps need WiFi?

Sometimes google maps gives a notification that goes something like:

"for increased accuracy please turn on the Wifi"

I can understand if it said "For faster loading of map layers....", but how can a better internet connection result in increased accuracy by the GPS?

Answer

You might be interested in Assisted GPS

Assistance falls into two categories:

• Information used to more quickly acquire satellites
  
  
  
  • It can supply orbital data or almanac for the GPS satellites to the GPS receiver, enabling the GPS receiver to lock to the satellites more rapidly in some cases.
  
  
  • The network can provide precise time.
  
  
  • The device captures a snapshot of the GPS signal, with approximate time, for the server to later process into a position.
  
  
  • Accurate, surveyed coordinates for the cell site towers allow better knowledge of local ionospheric conditions and other conditions affecting the GPS signal than the GPS receiver alone, enabling more precise calculation of position. (See also Wide Area Augmentation System and CellHunter.)
  
  
  
  


• Calculation of position by the server using information from the GPS receiver
  
  
  
  
  • The assistance server has a good satellite signal, and plentiful computation power, so it can compare fragmentary signals relayed to it by GPS receivers, with the satellite signal it receives directly, and then inform the GPS receiver or emergency services of the GPS receiver's position.
  
  
  
  

Many mobile phones combine A-GPS and other location services including Wi-Fi Positioning System and cell-site triangulation and sometimes a hybrid positioning system.[4]