A Providers Forum was established at the second meeting of the International Committee on Global Navigation Satellite Systems (ICG) in 2007, in Bangalore, India, with the aim to promote greater compatibility and interoperability among current and future providers of the Global Navigation Satellite Systems (GNSS). The current members of the Providers Forum, including China, India, Japan, the European Community, the Russian Federation and the United States, addressed key issues such as ensuring protection of GNSS spectrum and matters related to orbital debris/orbit de-confliction.
Global and regional system providers at the third meeting of the Providers' Forum in 2008, in Pasadena, United States of America, agreed that at a minimum, all global navigation satellite systems (GNSS) signals and services must be compatible. To the maximum extent possible, open signals and services should also be interoperable, in order to maximize benefit to all GNSS users. For many applications, common carrier frequencies are essential to interoperability and commonality of other signal characteristics is desirable. In some cases, carrier frequency diversity may be preferable to improve performance. The Providers' Forum will continue to investigate the benefits of carrier frequency commonality and diversity, as well as of compatibility and interoperability, as these latter terms are defined below:
Interoperability refers to the ability of global and regional navigation satellite systems and augmentations and the services they provide to be used together to provide better capabilities at the user level than would be achieved by relying solely on the open signals of one system:
(i) Interoperability allows navigation with signals from different systems with minimal additional receiver cost or complexity;
(ii) Multiple constellations broadcasting interoperable open signals will result in improved observed geometry, increasing end-user accuracy everywhere and improving service availability in environments where satellite visibility is often obscured;
(iii) Geodetic reference frames realization and system time steerage standards should adhere to existing international standards to the maximum extent practical;
(iv) Any additional solutions to improve interoperability should be encouraged.
Compatibility refers to the ability of global and regional navigation satellite systems and augmentations to be used separately or together without causing unacceptable interference and/or other harm to an individual system and/or service:
(i) The International Telecommunication Union provides a framework for discussions on radiofrequency compatibility. Radiofrequency compatibility should involve thorough consideration of detailed technical factors, including effects on receiver noise floor and cross-correlation between interfering and desired signals;
(ii) Compatibility should also respect spectral separation between each system's authorized service signals and other systems' signals. Recognizing that some signal overlap may be unavoidable, discussions among providers concerned will establish the framework for determining a mutually acceptable solution;
(iii) Any additional solutions to improve compatibility should be encouraged.
The Global Postioning System (GPS) is a United States space-based radio-navigation system that provides reliable positioning, navigation, and timing services to users on a continuous worldwide basis-freely available to all. The outstanding performance of GPS over many years has earned the enduring confidence of millions of international users. With its ongoing modernization programme, GPS will continue to provide superb quality and performance in the future.
The Wide Area Augmentation System (WAAS) augments GPS over the North American territory to provide the additional accuracy, integrity and availability needed to enable users to rely on GPS for safety-critical applications, particularly in the field of aviation.
Available Online Resources
The Russian GLObal NAvigation Satellite System (GLONASS), navigation satellite system is based on a constellation of active satellites which continuously transmit coded signals in two frequency bands that can be received by users anywhere on the Earth's surface to identify their position and velocity in real time based on ranging measurements. In the future a third frequency for GLONASS signal transmission will be introduced. In some areas of application, the use of combined GPS, GLONASS and GALILEO constellation appears to be preferable option.
The System of Differential Correction and Monitoring (SDCM) is intended for development and real-time transfer of the adjusting information for GLONASS, GPS and GALILEO systems (integrity data, wide-area and local correction data) to civilian customers. It is expected that SDCM based on GLONAS/SGPS signals will provide increased (in comparison with basic level) accuracy of position determination in real time at any point in the Russian Federation.
Available Online Resources
The European Satellite Navigation System (GALILEO), an initiative launched by the European Commission and the European Space Agency, will be a global navigation satellite system, owned by the European Union providing highly accurate, guaranteed global positioning services under civilian control. The Galileo Open Services signal will be interoperable with the GPS civil signal, as well as with GLONASS.
The European Geostationary Navigation Overlay Service (EGNOS) is a Satellite-based Augmentation System (SBAS) providing service for safety critical applications in Europe. As a first element of European GNSS capabilities, EGNOS will be integrated in the GALILEO programme.
Available Online Resources
The existing three-satellite COMPASS/BeiDou navigation system has played an important role in offering efficient positioning, timing, communication services and differential GPS information in surveying, telecommunications, transportation, meteorology, forest fire prevention, disaster forecast and public security areas. On the basis of the COMPASS/BeiDou Navigation Test System, China has started to build a system with global coverage.
The GPS aided Geo Augmented Navigation (GAGAN/IRNSS) has been taken up with an objective to demonstrate the Satellite-based Augmentation System (SBAS) technology over the Indian region. It is planned to be an operational system to provide a seamless navigation facility in the region, which is interoperable with other SBASs. Although primarily meant for civil aviation, it is beneficial for the other users.
The MTSAT (Multi-functional Transport Satellite) Satellite-based Augmentation Systems (MSAS) is one of the SBASs (Satellite-based Augmentation System) compliant with ICAO Standards and Recommended Practices (SARPs). This system provides navigation services for all the aircraft within Japanese airspace via two geostationary satellites (MTSAT-1R and MTSAT-2).
The Quasi-Zenith Satellite System (QZSS), promoted by Japan, is the Asian and Oceanian regional system that will serve as enhancement for GPS. QZSS was designed so as to guarantee that at any time at least one of its three satellites is close to the zenith over Japan.
Template for Information Sharing between Service Providers
|
|
Nominal Constellation |
Full operational capability |
Number of operational satellites |
Coverage |
Civilian Spectrum |
|
GPS |
24 |
1995 |
30
|
Global |
Current 2009: L1 C/A, L2C
|
|
WAAS |
3 |
IOC/2003
|
2 |
Regional
|
Current: L1C/A, L5
|
|
GLONASS |
24 |
1995
|
24
|
Global |
Current 2007: L1PT, L2PT
* signal structure is under refinement
|
|
SDCM |
2 |
2014 (expected) |
2 geostationary satellites |
Wide area
|
SBAS L1 C/A
|
|
GALILEO |
30 (MEOs) |
2014 |
2 MEOs |
Global |
E5 OS/SoL
|
|
EGNOS |
3 (GEOs) |
2009 for open service 2010 for safety-of-life service |
3 GEOs | Regional | Current: L1C/A |
|
COMPASS/BeiDou |
5 (GEOs) + 30 (non GEOs) |
2020 |
6
|
Global |
1,559.052 ~ 1,591.788 MHz
|
|
GAGAN/IRNSS |
3/7 |
2013/2014 |
|
Regional |
GAGAN: L5, L1 IRNSS: S,L5 and L1 IRNSS: S, L5, L1 |
|
MSAS |
2 GEOs |
|
2 GEOs
|
Asia, Pacific |
L1
|
|
QZSS |
1 (1st phase) 3 (2nd phase) 1 |
|
1
|
Regional
|
L1 C/A, L1C, L2C, L5, L1-SAIF (L1-submeter-class augmentation with integrity function), LEX (L-Band Experimental Signal) 1 The QZSS plan will basically proceed to the 2nd stage on government-private cooperation, after the evaluation of the results of technological verifications and demonstrations of the 1st stage |