>> GPS > Applications > Telecom/Wireless

GPS Testing for Telecom/Wireless Applications

What are the Key Location Based Services Testing Issues?

Location-based services (LBS) are being rapidly deployed by wireless service providers worldwide. Test specifications for position location technologies are being developed by organizations such as 3GPP2 (IS-916), the Open Mobile Alliance (OMA) and leading CDMA and WCDMA carriers. Originally driven in the U.S. by the FCC Enhanced 911 (E911) ruling, LBS has moved beyond emergency services to a growing range of commercial applications.

Wireless service providers need to meet or exceed industry specifications in order to compete and thrive in the rapidly expanding wireless market.

Testing Approaches

There are two high-level approaches to the required testing:

• Test devices in the field with real GPS signals and LTE infrastructure
• Test devices in the lab with simulated GPS signals and LTE interference

While field testing obviously has the benefit of being 'real-world', the challenge with this approach is that GPS satellites are not geostationary, so they are always moving and LTE signals are always fluctuating. As a result, it is almost impossible to repeat test conditions precisely in the field, which makes meaningful device-to-device comparisons, or comparisons with and without the presence of interference, very challenging.

So while there will be a field test element in the overall plan, there is considerable focus on the use of lab-based testing, with precise simulation of the GPS and terrestrial signals. Lab-based testing ensures accurate and repeatable test conditions - very important when trying to characterize GPS receiver performance with and without interference present. Another advantage of lab-based testing is that it makes it easier to ensure very precise control of signal levels. This is especially critical because the exact ratio of L-Band terrestrial interference to GPS power at which any performance degradation occurs is a key area of interest.

For lab-based testing of most receiver categories, simulation of the GPS constellation is carried out using a Spirent GPS Simulator, which is able to precisely simulate the GPS signals at any point in time in any location, as well as the impact of receiver motion and environmental conditions.

Spirent Solves Your Critical Test Challenges.

Spirent offers the world's first commercially available, automated systems to test CDMA, WCDMA and GSM mobile devices using A-GPS location technology. Spirent is taking a lead role in the development of test requirements and specifications for commercial location technologies, working with all key players to develop test requirements.

While current industry standard tests define only minimum-performance specifications, Spirent's systems evaluate performance well beyond these baseline test scenarios to identify performance breakpoints under real-world nominal and adversarial conditions.

Why Test with Spirent?

• Combined expertise in GPS and wireless testing
• Spirent systems enable testing with recognized industry standards
• Test capabilities for emergency and commercial LBS
• Performance testing beyond minimum standards to enable full evaluation of user experience