What is the A in A-GPS?

Assisted-GPS (A-GPS) dramatically improves speed and reliability of position fixes for Location Based Services (LBS) using an assistance server to provide satellite information that makes it faster and easier to lock onto GPS satellites.

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Spirent offers a complete range first-to-market performance and conformance test solutions for key location technology areas with A-GNSS/WiFi hybrid positioning, A-GPS LTE, A-GPS SUPL 2.0, A-GPS Over-the-Air (OTA), A-GLONASS and more.

Provisioning of assistance data to a GPS receivers greatly improves the Time To First Fix (TTFF) and increases its sensitivity. A-GPS offers significant performance advantages over autonomous GPS, particularly at the very low power levels often associated with consumer usage in urban and indoor environments.

GLONASS + GPS Improves Performance

Similar to GPS, GLONASS is a satellite navigation system maintained by the Russian government. GLONASS helps improve LBS performance in difficult environments when used in conjunction with GPS. Calculating device position requires at least three satellite signals. Devices that use both GPS and GLONASS almost double the number of usable satellites in the sky compared to GPS alone. Therefore, GPS+GLONASS devices have a greater chance of receiving more “line-of-sight” signals which subsequently improves the accuracy and reliability of position fixes—especially in urban environments.

A-GPS Over-The-Air (OTA) Performance

With its A-GPS Over The Air test solutions Spirent brings A-GPS expertise and industry leadership to an OTA test environment. Spirent’s OTA options offer full automation of all A-GPS OTA tests in the CTIA Test Plan for Mobile Station over the air performance. Customizable parameters enable test time optimization, as well as testing beyond the requirements of
industry standards.

Offering LBS over CDMA, UMTS, and LTE

With the introduction of LTE technology new A-GPS requirements are expected that will add to the device complexity. The most notable requirement is the need to support SUPL 2.0 protocol, a required for some, but not all, LTE carriers. Spirent is the leader in SUPL testing and continues to work with many A-GPS R&D companies to provide LTE, WCDMA, and CDMA SUPL 2.0 test solutions to its customers as the technology develops.

More Info

EE Times Article: Hybrid Location Technologies on Mobile Devices, Nov. 2009 

Application Note 121: Testing Real-World A-GNSS Performance in the Lab using ULTS