Assisted-GPS/LBS Testing

Assisted-GPS/LBS Test Solutions

What are the Key Location Based Services Testing Issues?

A-GPS offers significant performance advantages over autonomous GPS, particularly at low power levels often associated with consumer applications. Testing should simulate both UE-Based and UE-Assisted operating modes and synchronization to other systems such as network location servers. Conformance testing is often in accordance with standards from organizations such as 3GPP (IS-916), the Open Mobile Alliance (OMA) and leading carriers.

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 test systems for A-GPS development range from provision of assistance data to the device under test through to integrated wireless network and GPS environment simulation with full conformance and performance test capabilities. Spirent also offers production test systems for A-GPS devices.

Why Test with Spirent?
  • Assistance data available in a file or in real time, depending on system
  • Assisted-GPS development system integrating standard 3GPP and OMA test cases
  • RRC, RRLP and SUPL support
  • Advanced multipath and environment modeling
  • Low signal power modeling
  • Flexible, programmable SMLC emulator enables call flow definition and LCS message content
  • Manufacturing/production test systems including assistance data provision if required
Spirent simulators accelerate A-GPS testing required by the FCC mandate for E911

   Spirent simulators accelerate A-GPS testing
   required by the FCC mandate for E911

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