ESA ALIVE Initiative A Satellite-Based Communication Channel for the Reliable Distribution of Early Warning Messages The Alert Interface via EGNOS (ALIVE) for Disaster Prevention and Mitigation
Presentation Topics • The requirements for an alert system • Overview of SBAS (Satellite Based Augmentation Systems) • How SBAS meets the alert requirements • The ALIVE concept • Possible implementation strategy
The Need for an Alert System • Disasters are as devastating to advanced nations as they are to third world~ • Arguably, we are more reliant on technology • ‘ 000’s of lives can be saved by early warning and mitigation • Disasters do not respect national boundaries • But one type of communications channel cannot meet the needs of all citizens at all times
High Level Requirements • Resilient from terrestrial infrastructure damage • High level of integrity • Institutionally owned • End user device must be ubiquitous • Global standard, integrated into disaster management centres • Cope with several contemporaneous events
Presentation Topics • The requirements for an alert system • Overview of SBAS (Satellite Based Augmentation Systems) • How SBAS meets the alert requirements • The ALIVE concept • Possible implementation strategy
SBAS – an augmentation to GPS
EGNOS – where we are today • EGNOS is due to become operational in Mar 08 • Technical performance already stable • Differential corrections for GPS • Upgradeable to other GNSS including Galileo • 1 -2 m accuracy from wide area corrections • Equivalent to commercial DGPS services • Integrity alert within 6 seconds if position information is deemed unreliable • Free to air at point of end use • Signals received via geostationary satellite in same frequency band as GPS
Satellite-based Augmentation Systems • Three SBAS Systems: • USA: Wide Area Augmentation System (WAAS) • JAPAN: Multifunction Satellite Augmentation System (MSAS) • EUROPE: European Geostationary Navigation Overlay System (EGNOS) • Global service interoperability
SBAS Characteristics • Institutionally controlled, secure, operated for safety of life applications • Designed to: • guarantee adequate message broadcast • provide integrity of messages • provide confirmation of transmission • Receivers are: • based on GPS receivers • share same globally accepted standards • are the most abundant “satellite communication receivers” in the world • Receivers combine capability of receiving messages with the ability to: • determine the location of the receiver • the three existing SBAS together provide a global coverage
Presentation Topics • The requirements for an alert system • Overview of SBAS (Satellite Based Augmentation Systems) • How SBAS meets the alert requirements • The ALIVE concept • Possible implementation strategy
The disaster alert proposal… • Communication capacity larger than required for system operation - sufficient margin to send additional ALIVE messages • Inherent characteristics appropriate for alert messages • Ground-based infrastructure is very unlikely to be affected by a disaster/crisis • SBAS communication channel cannot be disrupted in a crisis situation (ARNS protected bands) Unique opportunity for broadcasting of alert messages
How SBAS Meets Alert requirements • SBAS receivers get alert messages and also have their position simultaneously - only users in target areas need to act • Unique worldwide standard - all SBAS receivers are identical • SBAS operated with all guarantees - Safety of Life, Institutional control, 24 hours non stop; confirmation message is broadcast in time • Can be implemented in very short time • Works in places with no operational infrastructure • Potential global coverage together with all other SBAS
EGNOS Capability • EGNOS has to respect minimum update rate to comply with safety of life requirements – primary mission. • Possibly 35% of bandwidth is available • A 250 -bit message every 3 -4 seconds (75 bps) • Without SA this increases to 140 bps • Compares favourably to SAR preliminary mission analysis requirement of 7 bps.
Presentation Topics • The requirements for an alert system • Overview of SBAS (Satellite Based Augmentation Systems) • How SBAS meets the alert requirements • The ALIVE concept • Possible Implementation Strategy
The Alert Interface Via EGNOS (ALIVE) • The architecture of ALIVE implementation….
Presentation Topics • The requirements for an alert system • Overview of SBAS (Satellite Based Augmentation Systems) • How SBAS meets the alert requirements • The ALIVE concept • Possible Implementation Strategy
Key implementation issues • Need for global coverage and international co-operation • Technical feasibility and potential affects on core EGNOS mission • Receiver compatibility and functionality and implications for device manufacturers • System architecture definition and requirements for on-board database – thin or thick client? • Institutional convergence amongst interested governments and agencies • Development of revised SBAS international standards • The need for a flexible data interchange format for collecting and distributing early warnings over information networks and the potential adoption of the OASIS CAP standard
Possible Implementation Strategy Step 1: Presentation of the ALIVE concept to relevant Disaster Management authorities (in progress) Step 4: Propose the SBAS communication functionality (incl. ALIVE) in the context of the GNSS Accompanying Program for ESA delegations consideration Step 6: SBAS communication function (incl ALIVE mission) Implementation Phase and development of SBAS ALIVE enabled receivers 2: Step 3: Cons olidation of ibility ALIVE asse ssment of Mission SBA Requi S rements with funct expert ionality, groups Step 5: Detailed specifications; message Step standardization; detailed 8: Disa definition study; test services Step through EGNOS test Bed ; ster prev 7: SBAS ALIVE enabled receiver detailed design. entio Opera n/mit tional igati integr on ation quali of the ficati SBAS on comm. and functio start nality of (inc oper ALIVE ation Feas
Conclusions • SBAS cannot be regarded as ‘one stop shop’ for disaster alert broadcast channel • Must be seen in context of suite of channels designed to meet specific needs of citizens • Commercial satellite communications • Public mobile networks • Public fixed networks • Private mobile data • Terrestrial broadcast (TV, Radio) • Internet/email • Public address
SBAS – an effective, complementary and inexpensive disaster alert broadcast channel • The three existing SBAS together provide global coverage and share the same worldwide accepted standards • SBAS GPS combine the possibility of warning with the ability to determine the location of the receiver in the same equipment • The SBAS systems, having been conceived as safety critical systems with the necessary built-in features to guarantee timeliness of delivery, confirmation of transmission and service availability • SBAS are institutionally controlled and may readily support the necessary regulated structures to control service access • SBAS offers a very low operational cost suitable for a public service when compared to most other solutions • SBAS (like other space systems) offers survivability in the event of many (terrestrial) disasters as well as speedy restoration after the event
Thank you for your attention Andrew. sage@helios-tech. co. uk Javier. Ventura-Traveset@esa. int Felix. Toran@esa. int
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