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{{Article Infobox2
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|Category=EGNOS
|Title={{PAGENAME}}
|Editors=GMV
|Authors=GMV.
|Level=Basic
|Level=Basic
|YearOfPublication=2011
|YearOfPublication=2011
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In addition to EGNOS, there are other Satellite Based Augmentation Systems (SBAS) developed or under development, such as the [[WAAS General Introduction|Wide Area Augmentation System (WAAS)]] in USA, the multi-functional transport satellite (MTSAT) [[MSAS Space Segment|satellite-based augmentation system (MSAS)]], in Japan or the [[GAGAN|GAGAN system]] in India, [[Other SBAS|KASS]] in Korea, [[Other SBAS|SBAS ASECNA]] in Africa, [[SDCM|the System for Differential Corrections (SDCM)]] in Russia or the Australian SBAS test system (SPAN). Although all SBAS are currently defined as regional systems, it is commonly recognized the need to establish adequate co-operation/co-ordination among the different systems, so that their implementation becomes more effective and part of a seamless world-wide navigation system.<ref name=" The European EGNOS Project: Mission, Program and System Description">The European EGNOS Project: Mission, Program and System Description; J.Ventura-Traveset, L. Gauthier, F. Toran and P.Michel, ESA EGNOS Project office, European Space Agency (ESA); G. Solari and F. Salabert, Galileo Joint Undertaking (GJU); D. Flament, J. Auroy and D. Beaugnon, Alcatel Alenia Space </ref>


In addition to EGNOS, there are other Satellite Based Augmentation Systems (SBAS) under development: the wide area augmentation system (WAAS) in USA, the multi-functional transport satellite (MTSAT) satellite-based augmentation system (MSAS), in Japan, the GAGAN system in India and the SNAS system in China. Although all SBAS are currently defined as regional systems, it is commonly recognized the need to establish adequate co-operation/co-ordination among the different systems, so that their implementation becomes more effective and part of a seamless world-wide navigation system.<ref name=" The European EGNOS Project: Mission, Program and System Description">The European EGNOS Project: Mission, Program and System Description; J.Ventura-Traveset, L. Gauthier, F. Toran and P.Michel, ESA EGNOS Project office, European Space Agency (ESA); G. Solari and F. Salabert, Galileo Joint Undertaking (GJU); D. Flament, J. Auroy and D. Beaugnon, Alcatel Alenia Space </ref>
To guarantee seamless and worldwide system provision, it is essential that the existing systems do meet common [[SBAS Standards|standards]] and interoperability requirements. SBAS service providers are regularly meeting through the so called ''interoperability working group (IWG)'' to conclude on a precise understanding of the term interoperability, and on the identification of the necessary interfaces among SBAS that each conceivable interoperability scenarios may imply. Nowadays, IWG discussions focus on SBAS dual-frequency multi-constellation (DFMC) standards, civil aviation/maritime region applications, minimum operating standards (MOPS), and the Concept of Operations (CONOPS).<ref name=" BeiDou Navigation Satellite System ">[http://en.beidou.gov.cn/WHATSNEWS/201806/t20180615_15039.html 33rd IWG meeting]</ref>
 
To guarantee seamless and worldwide system provision, it is essential that the existing systems do meet some common interoperability requirements and do provide adequate system. The service providers of the EGNOS, WAAS and MSAS systems are regularly meeting through so called “interoperability working group (IWG)” meetings to conclude on a the precise understanding of the term interoperability, and on the identification of the necessary interfaces among SBAS that each conceivable interoperability scenarios may imply. The EGNOS system achieved.
 
In addition to interoperability, EGNOS has built-in expansion capability to enable extension of the services over regions within the Geostationary Broadcast Area of GEO satellites used, such as Africa, Eastern countries, and Russia.


The combination of SBAS Interoperability and expansion concepts should allow providing a true global world-wide navigation seamless service.
The combination of SBAS Interoperability and SBAS expansion concepts should allow providing a true global world-wide navigation seamless service.




==Other SBAS Systems==
==SBAS Systems==


[[File:SBAS_Interoperability2.JPG| SBAS Interoperability  |300px|thumb|right]]
[[File:SBAS Service Areas 2021.PNG|300px|SBAS Indicative Service Areas. Source: GSA User Technology Report 2020 <ref>[https://www.euspa.europa.eu/sites/default/files/uploads/technology_report_2020.pdf GSA User Technology Report 2020]</ref> |thumb]]


In the mid-1990s, three regions took up the gauntlet to develop SBAS systems: Europe, the US, and Japan.<ref name=" SBAS Interoperability">[http://www.egnos-pro.esa.int/Publications/2005%20Updated%20Fact%20Sheets/fact_sheet_14.pdf SBAS - Interoperability Explained - Delivering a Global Service]</ref>
From all the [[SBAS Systems|SBAS systems]] in the world, some are already operational ([[WAAS General Introduction|WAAS]] in North America, [[MSAS General Introduction|MSAS]]/QZSS in Japan, [[EGNOS General Introduction|EGNOS]] in Europe,[[GAGAN]] in India), other are under implementation (BDSBAS (formerly SNAS) in China, [[SDCM]] in Russia, KASS in South Korea) while others are under feasibility studies, for instance SACCSA, Australian SBAS (SPAN) or SBAS-ASECNA in Africa. As regards the operational SBAS:


In the United States of America, the Federal Aviation Administration has taken the lead for developing its Wide Area Augmentation System or WAAS. The WAAS signal  
*The [[WAAS General Introduction|Wide Area Augmentation System (WAAS)]] was jointly developed by the United States Department of Transportation (DOT) and the Federal Aviation Administration (FAA), beginning in 1994, to provide performance comparable to category I instrument landing system (ILS) for all aircraft possessing the appropriately certified equipment.<ref name="WAAS WIKI">[http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System Wide Area Augmentation System]</ref> On July 10, 2003, the WAAS signal was activated for safety-of-life aviation, covering 95% of the United States, and portions of Alaska.<ref name="WAAS WIKI"/> At present, WAAS supports en-route, terminal and approach operations down to a full LPV-200 (CAT-I like Approach Capability) for the CONUS, Mexico and Canada.
was made available for non-aviation users in 2000. It currently delivers accuracies of one meter horizontal and two meters vertical and supports aviation precision approach (APV-1) performance. An Initial Operational Capability (IOC) for aviation use started in July 2003 and its Full Operational Capability (FOC) is planned for the end of 2007.  
*The [[MSAS General Introduction|Multi-functional Satellite Augmentation System (MSAS)]] is the Japanese SBAS. NEC manufactured and delivered MSAS under contract with the Civil Aviation Bureau, Ministry of Land, Infrastructure, Transport and Tourism. MSAS is operational since 2007 supporting en-route, terminal and non-precision approach operations. MSAS evolutions will take advantage in the short term of the Quasi Zenith Satellite System deployed by Japan to broadcast radio signals from high elevation angle into urban canyons.
*[[EGNOS General Introduction|EGNOS]] is the European satellite-based augmentation service (SBAS) that complements the existing satellite navigation services provided by the US [[GPS General Introduction|Global Positioning System]] (GPS). EGNOS provides the first European GNSS services to users. The [[EGNOS Safety of Life Service|Safety of Life Service]] (SoL), which provides the most stringent level of signal-in-space performance to all communities of Safety of Life users over Europe, was officially started on 2 March 2011.EGNOS V3 will provide augmentation to both GPS and Galileo in L1/E1 and L5/E5a signals.
* The [[GAGAN|GPS Aided Geo Augmented Navigation System (GAGAN)]] is the SBAS implementation by the Indian government. The project has established 15 Indian reference stations, 3 Indian navigation load uplink stations and 3 Indian mission control centres, in order to navigate in the Indian airspace by an accuracy of 3m. On 30th December 2012, the Directorate General of Civil Aviation (DGCA), India provisionally certified the GAGAN system to RNP0.1 (Required Navigation Performance, 0.1 Nautical Mile) service level. The certification enabled aircraft fitted with SBAS equipment  to use GAGAN signal in space for navigation purposes. Testing and validation of these procedures were finished in 2016.
The new civil signals suitable for aviation both in GPS and Galileo, offers great number of dual frequency ranging measurements. Because of that, the Satellite Augmentation Systems can also be updated to exploit these new signals and be available for multi-constellation performances. Such updates offer a variety of improvements over existing single frequency systems. These dual frequency systems are fully robust against ionospheric disturbances. Furthermore, they offer improve resistance against interference as operations can proceed when aircraft lose access to one frequency or the other. However, the largest benefit to a user taking advantage of both frequencies is that their availability can extend much farther away from the reference station network, in addition to the eliminated ionospheric behavior, allow this increase in coverage.
An SBAS utilizes a network of precisely surveyed reference receivers, located throughout its coverage region. The information gathered from these reference stations monitors the GNSS satellites and their propagation in real-time. Availability of SBAS service is a function of two quantities: the arrangement of the pseudorange measurements used to determine the user`s position, referred to as geometry; and the quality of each individual measurement. Referred to as confidence bound. Although very small confidence bounds can make up for poor geometries, and strong geometries can overcome large confidence bounds, both values are generally required it be good to obtain high availability. <ref name="Coverage Improvement for Dual Frequency SBAS” T. Walter, J. Blanch and P. Enge.">[https://web.stanford.edu/group/scpnt/gpslab/pubs/papers/Walter_IONITM_2010.pdf  Coverage Improvement for Dual Frequency SBAS” T. Walter, J. Blanch and P. Enge.]</ref>


Japan is developing an SBAS founded on its Multi-function Transport Satellite (MTSAT) called the MTSAT Satellite Augmentation System or MSAS. The first phase based on single geostationary satellite coverage is planned for 2005 while the second phase based on dual geostationary satellite coverage is planned for 2006. We expect MSAS to deliver a Non Precision Approach capability, and this could be enhanced to provide precision approach performances (e.g. APV-1).  
==SBAS Standardisation==
There are two sets of International Standards which SBAS’s shall be compliant in order to be used by Civil Aviation Authorities:
*The Standards and Recommended Practices (SARPS) Standard for SBAS systems established and controlled by the International Civil Aviation Organization (ICAO)<ref name=" ICAO ">[https://www.icao.int  ICAO website]</ref> and which provides Standards regarding the type and content of data which must be generated and transmitted by an SBAS system. In general, the SBAS provider shall broadcast a SBAS Signal in Space (SIS) compliant to this standard in terms of radio-frequency characteristics, and data content and format.
*The Minimum Operational Performance Standard (MOPS) DO229 established and controlled by the US Radio Technical Commission for Aeronautics (RTCA)<ref name="RTCA">[http://www.rtca.org RTCA website]</ref> and which provides standards for SBAS receiver equipment. It must be taken into account that MOPS RTCA 229 is only for GPS and another MOPS standard is being developed for the dual frequency and multi-constellation systems.


Other regions, such as Japan, provide its own SBAS system, named MSAS (MTSAT-based satellite augmentation system).
For more information, please refer to the article [[SBAS Standards]].


==SBAS System Cooperation==
==SBAS System Cooperation==


SBAS Interoperability refers to the ability of SBAS systems and the services they provide to be used together to provide better capabilities at the user level than those achieved by relying solely on one of the systems. The SBAS interoperability has always been a prerequisite for delivering a global seamless safety-oflife service.<ref name=" EEGS Newsletter">[http://www.eegs-project.eu/joomla/images/stories/pdf/EEGS-GMV-NewsLetter-v1_2.pdf  EEGS Newsletter-September 2010]</ref>
SBAS Interoperability refers to the ability of SBAS systems and the services they provide to be used together to provide better capabilities at the user level than those achieved by relying solely on one of the systems. The SBAS interoperability has always been a prerequisite for delivering a global seamless Safety-of-Life service.
 
Although all SBAS are regional systems, it is commonly recognised the need to establish adequate co-operation/coordination among SBAS providers so that their implementation becomes more effective and part of a seamless world-wide navigation system. SBAS co-operation is currently co-ordinated through the so-called Interoperability Working Groups
(IWG).  Although interoperability implies a large variety of complex issues (such as certification, standards, safety, operations,…), EGNOS, WAAS, CWAAS and MSAS SBAS providers have agreed on the following list of objectives concerning technical interoperability and co-operation among SBAS:<ref name=" EGNO-MSAS Interoperability">[http://www.egnos-pro.esa.int/Publications/GNSS%201999/GNSS99_MSAS.pdf Interoperability Test Analysis between EGNOS and MSAS SBAS Systems; Jorge Nieto, Joaquin Cosmen, Ignacio García,  GMV, S.A.; Javier  Ventura-Traveset, Isabel Neto, European Space Agency (ESA); Bernd Tiemeyer, Nicolas Bondarenco, Eurocontrol Experimental Centre; Kazuaki  Hoshinoo,  ENRI Institute, Japan] </ref>
 
==SBAS Interoperability Studies==
 
Being SBAS system interoperability a critical issue, diverse studies are being carried out in order to draw design and operational considerations.
 
In this context, SBAS service areas  will overlap and, considering that there may co-exist different SBAS signals in the boundary regions, two important issues are to be noted:<ref name=" EEGS Project Web site">[http://www.eegs-project.eu/joomla/ EEGS Project Web site] </ref>


* EGNOS and SDCM will have a different SV mask. This is not a problem since the receiver shall maintain an information database per GEO PRN signal and then the transition
Although all SBAS are regional systems, it is commonly recognised the need to establish adequate co-operation/coordination among SBAS providers so that their implementation becomes more effective and part of a seamless world-wide navigation system. SBAS co-operation is currently coordinated through the so-called Interoperability Working Groups
between one GEO to the other will not be affected by different SV masks.
(IWG).  Although interoperability implies a large variety of complex issues (such as certification, standards, safety, operations,…), EGNOS, WAAS and MSAS SBAS providers among others agreed on the following list of objectives concerning technical interoperability and co-operation among SBAS:<ref name=" EGNO-MSAS Interoperability">[http://www.egnos-pro.esa.int/Publications/GNSS%201999/GNSS99_MSAS.pdf Interoperability Test Analysis between EGNOS and MSAS SBAS Systems; Jorge Nieto, Joaquin Cosmen, Ignacio García,  GMV, S.A.; Javier  Ventura-Traveset, Isabel Neto, European Space Agency (ESA); Bernd Tiemeyer, Nicolas Bondarenco, Eurocontrol Experimental Centre; Kazuaki  Hoshinoo,  ENRI Institute, Japan] </ref>
* SDCM will provide corrections and integrity for GLONASS satellites. At SARPS level, the information to be broadcast by a service provider both for GPS and GLONASS
*Objective 1 – Validate SBAS Performance consistency and SARPs compliance.
constellations is defined. However, at MOPS level, there are just minimum operational requirements for airborne navigation equipment using GPS augmented by SBAS. The not-consideration of the GLONASS constellation is a major issue which will have to be properly tackled before a Safety-of-Life service can be provided for GLONASS
*Objective 2 – Improve the service level available in the regions outside the nominal SBAS service volumes.
satellites.
*Objective 3 – Improve individual system performance through SBAS data interchange.
*Objective 4 – Improve SBAS prediction capability through SBAS data interchange.
*Objective 5 – Identify possible future improvements.


Having said that at standards level there is no problem for EGNOS and SDCM interoperability in any of the operational modes, at present no EGNOS-SDCM interoperability is possible, mainly due to  the fact that the systems are not ready to be used for Safety-of-Life and also since SDCM is intended for GLONASS satellites too which are not currently covered by the MOPS standard. Solving these issues will lead to an operational EGNOS/SDCM Interoperability.
SBAS interoperability studies and discussions are currently been focused on two main set of topics:
*Interoperability issues concerning existing SBAS systems, in particular transition issues as observed by users crossing two SBAS service areas (GEO selection mechanism, activation of GEO ranging, etc).
*Interoperability issues for future SBAS evolutions:
**Evolution of SBAS to become multi-constellation (e.g., GPS and GLONASS or GPS and Galileo).  
**Evolution of SBAS to become multi-frequency (L1, L5, L1/L5).
**Potential evolution towards a combination of SBAS and RAIM techniques.


==Notes==
==Notes==

Latest revision as of 06:28, 1 October 2021


EGNOSEGNOS
Title SBAS Interoperability
Edited by GMV
Level Basic
Year of Publication 2011
Logo GMV.png

In addition to EGNOS, there are other Satellite Based Augmentation Systems (SBAS) developed or under development, such as the Wide Area Augmentation System (WAAS) in USA, the multi-functional transport satellite (MTSAT) satellite-based augmentation system (MSAS), in Japan or the GAGAN system in India, KASS in Korea, SBAS ASECNA in Africa, the System for Differential Corrections (SDCM) in Russia or the Australian SBAS test system (SPAN). Although all SBAS are currently defined as regional systems, it is commonly recognized the need to establish adequate co-operation/co-ordination among the different systems, so that their implementation becomes more effective and part of a seamless world-wide navigation system.[1]

To guarantee seamless and worldwide system provision, it is essential that the existing systems do meet common standards and interoperability requirements. SBAS service providers are regularly meeting through the so called interoperability working group (IWG) to conclude on a precise understanding of the term interoperability, and on the identification of the necessary interfaces among SBAS that each conceivable interoperability scenarios may imply. Nowadays, IWG discussions focus on SBAS dual-frequency multi-constellation (DFMC) standards, civil aviation/maritime region applications, minimum operating standards (MOPS), and the Concept of Operations (CONOPS).[2]

The combination of SBAS Interoperability and SBAS expansion concepts should allow providing a true global world-wide navigation seamless service.


SBAS Systems

SBAS Indicative Service Areas. Source: GSA User Technology Report 2020 [3]

From all the SBAS systems in the world, some are already operational (WAAS in North America, MSAS/QZSS in Japan, EGNOS in Europe,GAGAN in India), other are under implementation (BDSBAS (formerly SNAS) in China, SDCM in Russia, KASS in South Korea) while others are under feasibility studies, for instance SACCSA, Australian SBAS (SPAN) or SBAS-ASECNA in Africa. As regards the operational SBAS:

  • The Wide Area Augmentation System (WAAS) was jointly developed by the United States Department of Transportation (DOT) and the Federal Aviation Administration (FAA), beginning in 1994, to provide performance comparable to category I instrument landing system (ILS) for all aircraft possessing the appropriately certified equipment.[4] On July 10, 2003, the WAAS signal was activated for safety-of-life aviation, covering 95% of the United States, and portions of Alaska.[4] At present, WAAS supports en-route, terminal and approach operations down to a full LPV-200 (CAT-I like Approach Capability) for the CONUS, Mexico and Canada.
  • The Multi-functional Satellite Augmentation System (MSAS) is the Japanese SBAS. NEC manufactured and delivered MSAS under contract with the Civil Aviation Bureau, Ministry of Land, Infrastructure, Transport and Tourism. MSAS is operational since 2007 supporting en-route, terminal and non-precision approach operations. MSAS evolutions will take advantage in the short term of the Quasi Zenith Satellite System deployed by Japan to broadcast radio signals from high elevation angle into urban canyons.
  • EGNOS is the European satellite-based augmentation service (SBAS) that complements the existing satellite navigation services provided by the US Global Positioning System (GPS). EGNOS provides the first European GNSS services to users. The Safety of Life Service (SoL), which provides the most stringent level of signal-in-space performance to all communities of Safety of Life users over Europe, was officially started on 2 March 2011.EGNOS V3 will provide augmentation to both GPS and Galileo in L1/E1 and L5/E5a signals.
  • The GPS Aided Geo Augmented Navigation System (GAGAN) is the SBAS implementation by the Indian government. The project has established 15 Indian reference stations, 3 Indian navigation load uplink stations and 3 Indian mission control centres, in order to navigate in the Indian airspace by an accuracy of 3m. On 30th December 2012, the Directorate General of Civil Aviation (DGCA), India provisionally certified the GAGAN system to RNP0.1 (Required Navigation Performance, 0.1 Nautical Mile) service level. The certification enabled aircraft fitted with SBAS equipment to use GAGAN signal in space for navigation purposes. Testing and validation of these procedures were finished in 2016.

The new civil signals suitable for aviation both in GPS and Galileo, offers great number of dual frequency ranging measurements. Because of that, the Satellite Augmentation Systems can also be updated to exploit these new signals and be available for multi-constellation performances. Such updates offer a variety of improvements over existing single frequency systems. These dual frequency systems are fully robust against ionospheric disturbances. Furthermore, they offer improve resistance against interference as operations can proceed when aircraft lose access to one frequency or the other. However, the largest benefit to a user taking advantage of both frequencies is that their availability can extend much farther away from the reference station network, in addition to the eliminated ionospheric behavior, allow this increase in coverage. An SBAS utilizes a network of precisely surveyed reference receivers, located throughout its coverage region. The information gathered from these reference stations monitors the GNSS satellites and their propagation in real-time. Availability of SBAS service is a function of two quantities: the arrangement of the pseudorange measurements used to determine the user`s position, referred to as geometry; and the quality of each individual measurement. Referred to as confidence bound. Although very small confidence bounds can make up for poor geometries, and strong geometries can overcome large confidence bounds, both values are generally required it be good to obtain high availability. [5]

SBAS Standardisation

There are two sets of International Standards which SBAS’s shall be compliant in order to be used by Civil Aviation Authorities:

  • The Standards and Recommended Practices (SARPS) Standard for SBAS systems established and controlled by the International Civil Aviation Organization (ICAO)[6] and which provides Standards regarding the type and content of data which must be generated and transmitted by an SBAS system. In general, the SBAS provider shall broadcast a SBAS Signal in Space (SIS) compliant to this standard in terms of radio-frequency characteristics, and data content and format.
  • The Minimum Operational Performance Standard (MOPS) DO229 established and controlled by the US Radio Technical Commission for Aeronautics (RTCA)[7] and which provides standards for SBAS receiver equipment. It must be taken into account that MOPS RTCA 229 is only for GPS and another MOPS standard is being developed for the dual frequency and multi-constellation systems.

For more information, please refer to the article SBAS Standards.

SBAS System Cooperation

SBAS Interoperability refers to the ability of SBAS systems and the services they provide to be used together to provide better capabilities at the user level than those achieved by relying solely on one of the systems. The SBAS interoperability has always been a prerequisite for delivering a global seamless Safety-of-Life service.

Although all SBAS are regional systems, it is commonly recognised the need to establish adequate co-operation/coordination among SBAS providers so that their implementation becomes more effective and part of a seamless world-wide navigation system. SBAS co-operation is currently coordinated through the so-called Interoperability Working Groups (IWG). Although interoperability implies a large variety of complex issues (such as certification, standards, safety, operations,…), EGNOS, WAAS and MSAS SBAS providers among others agreed on the following list of objectives concerning technical interoperability and co-operation among SBAS:[8]

  • Objective 1 – Validate SBAS Performance consistency and SARPs compliance.
  • Objective 2 – Improve the service level available in the regions outside the nominal SBAS service volumes.
  • Objective 3 – Improve individual system performance through SBAS data interchange.
  • Objective 4 – Improve SBAS prediction capability through SBAS data interchange.
  • Objective 5 – Identify possible future improvements.

SBAS interoperability studies and discussions are currently been focused on two main set of topics:

  • Interoperability issues concerning existing SBAS systems, in particular transition issues as observed by users crossing two SBAS service areas (GEO selection mechanism, activation of GEO ranging, etc).
  • Interoperability issues for future SBAS evolutions:
    • Evolution of SBAS to become multi-constellation (e.g., GPS and GLONASS or GPS and Galileo).
    • Evolution of SBAS to become multi-frequency (L1, L5, L1/L5).
    • Potential evolution towards a combination of SBAS and RAIM techniques.

Notes

References