How to Test A-GPS Capable Cellular Devices and Why Testing is Required

Transcription

1 How to Test A-GPS Capable Cellular Devices and Why Testing is Required Presented by: Agilent Technologies Page 1

2 Agenda Introduction to A-GPS Why Test A-GPS Performance? Types of A-GPS Testing Page 2

3 Origins of A-GPS: US FCC E-911 and EU E-112 Requirements U.S. FCC mandates that 100% of new digital handsets sold in the U.S. are Automatic Location Identification (ALI) capable Phase II of FCC E-911 implementation requires location accuracy within meters depending on location method Wireless carriers are responsible for meeting these requirements Assisted GPS (A-GPS) was developed to optimize coverage and location accuracy in impaired satellite reception areas such as inside structures or multipath fading European Union requires caller location information to be shared with emergency authorities when a 112 call is placed Page 3

4 GPS vs A-GPS: Time To First Fix < 20secs! Time To First Fix Up to 12min! Page 4

5 A-GPS worldwide deployment Percentage of phones shipping with integrated GPS receivers is increasing 90% of smart phones expected to have GPS by In 2008, only one in three smart phones had GPS. A-GPS capability is becoming a standard feature for smart phones Page 5

6 Trends in Applications using A-GPS Assisted GPS (A-GPS) has driven growth in high-precision applications like navigation, geotagging, and tracking Continued trend upward due to wide range of independently developed applications with location-based content Today s smart phone applications utilize A-GPS for everything from social networking and restaurant searching to mapping and stargazing Page 6

7 Overview Introduction to A-GPS Why Test A-GPS Performance? Types of A-GPS Testing Page 7

8 Why Test A-GPS Performance? Location Based Services End user satisfaction and safety depend on A-GPS performance The US wireless carriers tasked the CTIA with developing a test plan for determining over-the-air (OTA) performance of A-GPS devices. The CTIA currently operates a certification program that determines OTA performance of cellular radios. Version 3.0 of the CTIA Over-the-Air Performance Test Plan requires A-GPS testing. Wireless Carriers already require phones they purchase to have A-GPS OTA performance data. Page 8

9 Why Test A-GPS Performance? The Link Budget An over-the-air communication link is usually characterized by the concept of a link budget. The quality of the link is a function of: The radiated power of the transmitter The sensitivity of the receiver The quality of the radio channel between transmitter and receiver Includes path loss between transmitter and receiver as well as interference sources Page 9

10 Why Test A-GPS Performance? The Link Budget For traditional cellular networks, carriers have several choices to improve link quality Increase transmitted power (up to regulatory limits) Improve receiver sensitivity (up to physical limits) Move transmitter and receiver closer together (requires adding more base stations to increase network density) Reduce interference (where they have control over interferers) For A-GPS, the location and power of the transmitter are fixed by the design of the satellite network. Performance can only be improved by improving the performance of the A-GPS receiver. Page 10

11 Why Test Over-the-Air A-GPS Performance? The Antenna Assumption In practice, this is only a first approximation. Various interaction factors occur between the radio, antenna, device platform, and objects found in the near field of the device and alter the resulting performance of the device. These include: Impact of device body on radiation pattern Impact of head and hand on radiated performance Mismatch between antenna and receiver Platform interference (desensitization), including cellular radio Cabling effects Only by testing in a radiated over-the-air test environment can we be sure to capture the direct impact of all performance impairments on the A-GPS receiver. Page 11

12 Overview Introduction to A-GPS Why Test A-GPS Performance? Types of A-GPS Testing Page 12

13 Types of A-GPS Testing Over-the-Air A-GPS Bench-top Pre-conformance Conformance System Page 13

14 A-GPS Test Systems Base Station Emulator Signal Conditioning Satellite Simulator RF Switch Matrix Broadband Signal Analyzer RF Absorber Material Dual Polarized Measurement Antenna Communication Signal Path Measurement Signal Path DUT Multi-Axis Positioner Communication Antenna Fully Anechoic Chamber A-GPS OTA Test Setup (radiated) GPS Simulator Base Station Emulator A-GPS Design Verification/Functional Test Setup (conducted) Page 14

15 How do they differ? A-GPS OTA Test Setup (radiated) Base Station Emulator Signal Conditioning Satellite Simulator RF Switch Matrix Broadband Signal Analyzer RF Absorber Material Dual Polarized Measurement Antenna Communication Signal Path Measurement Signal Path DUT Multi-Axis Positioner Communication Antenna Fully Anechoic Chamber Fixed Parameters Satellite base location Relative power of satellites (sat to sat) Variable Parameters Antenna position Satellite power (composite) Page 15

16 How do they differ? A-GPS Design Verification/Functional Test Setup (conducted) GS-9000 SW and/or Location Server GPS Simulator Base Station Emulator Fixed Parameters Antenna position ( ideal antenna) Variable Parameters Satellite Power (composite) Relative Satellite power Satellite Scenario (base location i.e. Atlanta/Sydney Satellite orbital location with respect to mobile station Assistance data delivered Satellites LOS or multi-path Assistance data delivery method (user/control plane) Page 16

17 Conducted A-GPS Systems Design Verification System Perform What if analysis Room for design specific tests General less expensive Conformance System Parameters are pre-set Generally high cost Page 17

18 Design Verification/Functional Testing What if? Location T 0 T n Satellite Position Power Assistance Data Time Path Effects Page 18

19 A-GPS Test Solution Overview Satellite Simulator GPS Assistance Server Automation Software Location Server Emulator User Plane mode Control Plane mode Cellular Network Assistance Data Network Downlink: Coarse Time Ephemeris Data Location, Almanac User Base Station Emulator Page 19

20 What Now? Page 20

21 Agilent GS-9000 A-GPS Design Verification Systems Scalable systems for R&D engineers who are designing and testing A-GPS capabilities in chipsets and mobile devices. GS-9000 Standard R&D Product Life Cycle Prototype Phase Pre-Certification Certification GS-9000 Lite Page 21

22 GS9000-Lite Capabilities 3GPP Defined Test Cases 2G/3G (51.010/34.171) 6 +2 Sensitivity Coarse Time Alignment ( /5.2.1) Nominal Accuracy ( /5.3) Dynamic Range ( /5.4) TTFF (time to first fix) Raw satellite data (Satellite ID, C/No, Doppler, Code Phase, and Pseudo Range Error) Reporting of latitude and longitude with mobile based methodology 2D error calculation and reporting Multiple GPS scenarios (8) Individual satellite power control GPS time advancing Sensitivity searches Power Sweeps User friendly GUI, Test executive, test automation Page 22

23 GS9000 Standard Capabilities 3GPP Defined Test Cases 2G/3G (51.010/34.171) Sensitivity Coarse Time Alignment ( /5.2.1) Sensitivity Fine Time Alignment ( /5.2.2) 11 Nominal Accuracy ( /5.3) Dynamic Range ( /5.4) Multi-path performance ( /5.5) Moving Scenario and Periodic Update (5.6) SUPL Server Support TTFF (time to first fix) Raw satellite data (Satellite ID, C/No, Doppler, Code Phase, and Pseudo Range Error) Positions estimation with mobile assisted methodology Reporting of latitude and longitude with mobile based methodology 2D error calculation and reporting 12+ GPS Satellite Simulation User defined GPS scenarios Individual satellite power control GPS time advancing Sensitivity searches Power Sweeps Complete test executive for test plan creation and execution Page 23

24 A-GPS Automation Software Protocol Logging Assistance Data Generator Data Viewer GS-9000 Test Executive with A-GPS Libraries Calibration Page 24