A-GPS (Assisted GPS)

A-GPS (Assisted GPS) which assisted GPS technology, it can improve the performance of GPS satellite positioning system. Base stations by mobile operators can quickly locate it, is widely used with GPS-enabled mobile phone. GPS radio signals via satellite to locate. When the poor signal conditions, such as a city, many of these signals may be irregular buildings, walls or trees weakened. In such conditions, the non A-GPS navigation device may not be fast positioning, while the A-GPS base station system operator can quickly locate information. A-GPS A-GPS technology is a combination of network information and GPS base station for mobile station positioning information technology in the GSM / GPRS, WCDMA, CDMA2000 and TD-SCDMA networks. The technology needs to increase in the mobile phone GPS receiver module, and the transformation of mobile phone antenna, while the construction of the mobile network location server, the differential GPS base station equipment. If you want to improve the program in interior areas such as the positioning of the GPS signal shielding effectiveness, the program also addressed the need to add similar EOTD program in the position measurement unit (LMU). AGPS phone's base station will first address itself to the location server through the network; Location server according to the approximate location of the mobile phone transmission with the aid of GPS location-related information (including the GPS ephemeris and azimuth angle of pitch, etc.) to the phone; According to the phone's AGPS module supporting information (to enhance the GPS signal locks the first time the ability TTFF) GPS receiver the original signal; GPS mobile phone in the receives the original signal demodulated signal, computing pseudorange to the satellite phone (subject to a variety of GPS pseudo-range error for the effects of distance), and information transmitted over the network to the location server; Location server based on information coming from GPS pseudo-range positioning, and from other devices (such as differential GPS base station, etc.) of auxiliary information to complete the processing of GPS information, and to estimate the location of the phone; Location server the location of the mobile phone network to locate through the gateway or application platform. AGPS solution advantages: Mainly in its positioning accuracy. And other open areas outside its accuracy GPS work in a normal environment, up to 10 meters, called the current highest positioning accuracy of a positioning technology. Another advantage of the technology: the first time to capture the GPS signal is generally only a few seconds, unlike the first GPS acquisition time may be 2 to 3 minutes.
 Although AGPS technology, high positioning accuracy, the first GPS signal capture time is short, but the technology also has some disadvantages. First, the indoor positioning problem is still not satisfactorily resolved. In addition, AGPS positioning must be achieved through multiple network (up to six one-way transmission), which operators are considered taking up a lot of air resources. AGPS main problem is the user location service for mobile phones must be replaced unacceptable. And AGPS mobile phone power consumption than the average additional burden on certain indirectly shorten the standby time. In addition, the effectiveness of the problem is to use. The GPS system owned and controlled by the U.S. government, at a critical time (such as the Gulf War, the war on terror, etc.), civilian GPS service may be affected, AGPS positioning the business more difficult to work properly. Currently, AGPS solution provider mainly Snaptrack Qualcomm and its subsidiary companies, now only for CDMA and iDEN networks market in the near future will be the location technology for GSM networks. AGPS to use: 1. "Settings" --- connection - access points, inside to set up the GPRS settings, the name of gprs, (set, make sure the Internet via GPRS) 2. "Settings" - Connection - Packet data access point inside the input name: gprs 3. "Settings" - General - positioning --- choose built-in GPS positioning method and network-based.