1. Agenda Item 6
GNSS Development Status and Future Work Eric Chatre, EC/ESA Rapporteur Technical WG, GNSS Panel
Thank you…
Good morning…
I am ... and member of ATMCP.
The complete title of the presentation is: Need for the development of performance criteria and the concept of required total system performance (RTSP): It relates directly to the topics to be addressed under agenda item 3 of the Conference, but you will easily see connections with virtually all agenda items. Performance, including safety, provides a vehicle to discuss all aspects of Air Navigation from the planning stages to the monitoring of actual service delivery.

2. Outline GNSS Elements GNSS Performance Requirements
Definition of parameters
Relationship betweens parameters
Integrity Principles
GNSS Standards
Future Work

3. GNSS Elements Core Constellations GLONASS GPS Augmentations ABAS GBAS
IOR
ABAS
GBAS
SBAS

4. Aircraft-Based Augmentation System (ABAS)
Stand-alone technique implemented in user equipment/software
No accuracy improvement, lateral guidance only
Provides integrity based on consistency check
Needs redundant satellite measurements (5 or more satellites in view with good geometry)
Integrity only
Performance and availability limited to some phases of flight

5. Satellite-Based Augmentation System (SBAS)
Objectives
Improve accuracy of GPS or GLONASS by providing corrections for
Satellite errors : clock and ephemeris
Ionospheric errors : model over a geographic area
Provide integrity information
Lateral and vertical guidance
Improved availability,

6. Satellite-Based Augmentation System (SBAS) (cont.)
Architecture
Network of stations covering a wide area (e.g. continent)
Transmission of information to users through geostationary satellites
Coverage and Service areas
Coverage : Wherever the geostationary signals are received
Service : Wherever operations have been approved by States

7. SBAS Architecture GEO GPS Reference Stations Uplink Station SBAS
Master Station
Uplink
Station
GEO
GPS
SBAS
Message

8. Ground-Based Augmentation System (GBAS)
Objectives
Improve accuracy of GPS or GLONASS by providing for each satellite a composite correction
Satellite errors : clock, ephemeris correction valid locally
Ionospheric errors : local correction
Tropospheric errors : local correction
Provide integrity information

9. Ground-Based Augmentation System (GBAS)(cont.)
Architecture
Ground Reference Station (typically 1 per airport)
Transmission of information to users through a VHF data link (108 to 118 MHz)
Coverage
Approach area (ILS like coverage)
Terminal area (positioning service)

10. GPS and/or GLONASS, GEOs Reference station and VDB
GBAS Architecture
GPS and/or GLONASS, GEOs
User
Reference station and VDB
VHF DATA LINK

11. Aviation Performance Requirements for GNSS (signal-in-space)
Phase of
Flight
Accuracy
(95%)
Integrity Risk
Continuity Risk
Availability
En Route
H: 3.7 Km
1x10-7/h
1x10-4/h to x10-8/h
0.99 to
Terminal
H: 0.74 Km
NPA
H: 220 m
APV I
H: 16 m
V: 20 m
2x10-7/App
8x10-6/ 15s
APV II
V: 8m
Cat I
V: 6 to 4 m
Cat II/III
Surface Ops
Under Development

12. Interpretation of parameters
Accuracy : Characterize typical behavior of the system in presence of nominal error components
Integrity : Limit risk of abnormal behaviour of the system due to errors resulting from system failures
-Integrity Risk
-Alert Limit
-Time to Alert
Continuity : Limit risk of losing the service unexpectedly
Availability : Accuracy + Integrity [+ Continuity]

13. Relationship between parameters
Integrity
Accuracy
Continuity
Availability
Availabilty
-Vertical accuracy/integrity is usually the main driver
-Decreases as accuracy increases
-Decreases as alert limit gets smaller
GNSS performance is variable :
in time
in space
New approach to ensure integrity for all users
-Protection Level concept

14. Integrity principles Protection Level < Alert Limit  No Alert
User Computed Protection Level
Probability
Computed Position
Alert Limit
Protection Level < Alert Limit  No Alert
Protection Level > Alert Limit  Alert

15. GNSS Standards, Procedures, Guidance Material
Standards and Recommended Practices (ICAO Annex 10, Vol I)
GNSS NOTAMS and Phraseology (ICAO Annex 15, PANS-ABC Doc 8400, PANS- ATM Doc 4444)
Procedure Design Criteria (PANS-OPS, Doc 8168)
Geodetic Reference Datum and Data Base Requirements (ICAO Annexes 4,11,14 &15, WGS-84 Manual Doc 9674)
Information and guidance on implementation (GNSS Manual)
Industry Standards (RTCA and EUROCAE MOPS/MASPS)

16. Industry Standards The main actors are : The Documents
RTCA in the US, Special Committee 159
EUROCAE in Europe, Working Group 28
The Documents
Minimum Operational Performance Specifications (MOPS)
Minimum Aviation System Performance Standards (MASPS)
Existing Standards
ABAS/Basic GNSS receiver : DO-208 / ED-72 / (J)TSO-C129A
SBAS receiver : DO-229 C / TSO-145A/146A
GBAS Cat I receiver : DO-253A
Multi-Mode Receiver including GBAS : ED-88A

17. Future Work Evolution of currently standardized GNSS elements
GPS modernization with additional civil signal on L5 frequency ( MHz)
GLONASS modernization (GLONASS K) with additional civil signal in the MHz band
Extention of SBAS standards to accomodate new signals
Extention of GBAS standards to accomodate new signals and cover Category II/III and surface operations

18. Future Work (cont.) New GNSS elements
GALILEO system with 3 civil signals and a dedicated integrity service
Ground-Based Regional Augmentation System (GRAS)