1. Safety Critical Applications ETSC Best in Europe Conference 2006
with Galileo
ETSC Best in Europe Conference 2006
J. Cosmen / GMV
19/11/2018

2. Galileo Differenciators GNSS Road Applications
Contents
Galileo Differenciators
GNSS Road Applications
Galileo Added Value for Road
Integrity as a key factor for new Road Applications
Applications Needs vs. Galileo Capabilities
Conclusions
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3. Key Features: Galileo Differenciators
Galileo introduces, in addition to European independence, major improvements w.r.t. GPS:
New Services such as SAR
Improved signal characteristics
Civil Control
Built-in Service Integrity
Service guarantee through a Contractual Commitment (SLA)
Anticipated
in EGNOS
for Europe 
No need
to wait!
The main characteristics of Galileo have been already summarized by Mr. TBD. From our point of view, in addition [esto puede ser también “emphasizing en vez de “in addition” si algo a mencionado.] to all those characteristics and advantages, there are a couple of differenciators which are essential for its application to Civil Aviation
First, the built-in service integrity which is completely new from the other navigation systems[?lo llevan las nuevas versiones de GPS?: dicen que para el GPS III sí pero nadie sabe cómo; de hecho se piensa que lo que va a hacer GPSIIes un broadcast de WAAS]. This is a very important characteristic not only for classical safety critical applications but also for a new set of applications that we call “liability critical” where GNSS based position is used for commercial or legal applications that involve an associated liabiliy. Examples of this could be implementation of road pricing policies, speed control or tracking of parolees.
Second, Galileo performance, in particular integrity, are not only a technical issue but involves a contractual commitment from the service provider formalised through a service level agreement in such a way that a certain level of performances are guaranteed. This guaranty is a key factor in many business which involved the mentioned liability aspects.
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4. In addition...
… combined use of GPS + Galileo substantially improves availability in urban environments
- GPS -
- GPS+GALILEO+EGNOS
Results based on
>80%
<15%
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5. Classification of Road Applications
GIROADS proposes a classification according to the level of service guarantee requested:
Safety Critical
Liability Critical
No specific Guarantee Requirements
More Demanding
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6. Safety-Critical Applications
Term used in various domains as in civil aviation
Those in which GNSS errors can provoke situations potentially affecting health or life of human beings
What is Safety Critical in Road?:
ADAS (GNSS in the driving loop): errors can provoke accidents ->direct impact
Emergency services: errors may affect the service quality -> indirect impact
Concerning the first question we have identified the so called liability critical applications as the main users of postion integriy
What are those liability critical applications? those in which position is used for legal decisions or for economical transactions. This implies that large position errors although improbable, should they ocuur they may have a major negative legal or economical impact,.
Two examples may help to understand the concept. Imagine that we use the speed computed by a received as the basis for decide whether car is violating and speed limit. In order for this data to be used as legal proof we have to ensure that it will not include large errors that can be derived in incorrect fine.
The same occurs if position is used as the basis for charging. A chraging system cannot afford to charge a user incorrectly because of the GNSS position errors.
Probability of these bad consequences has to be extremely low to make them acceptable.
Then in liabiliy critcal applications we have to bound the probability of bad consequences and this implies to bound the position errors. I.e. Liability critical applications require position integrity
1m 20 sec
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7. Liability Critical Applications
Position used for legal decisions or economic transactions.
Large position errors, although improbable, might have a major legal or economical impact
Probability of these bad consequences has to extremely low to make them negligible
Examples in Road Applications:
Legal proof (e.g. speed limit enforcement): efficicent enforcement to reduce accidents -> also indirect impact on safety
Charging (e.g. road user charging)
Concerning the first question we have identified the so called liability critical applications as the main users of postion integriy
What are those liability critical applications? those in which position is used for legal decisions or for economical transactions. This implies that large position errors although improbable, should they ocuur they may have a major negative legal or economical impact,.
Two examples may help to understand the concept. Imagine that we use the speed computed by a received as the basis for decide whether car is violating and speed limit. In order for this data to be used as legal proof we have to ensure that it will not include large errors that can be derived in incorrect fine.
The same occurs if position is used as the basis for charging. A chraging system cannot afford to charge a user incorrectly because of the GNSS position errors.
Probability of these bad consequences has to be extremely low to make them acceptable.
Then in liabiliy critcal applications we have to bound the probability of bad consequences and this implies to bound the position errors. I.e. Liability critical applications require position integrity
1m 20 sec
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8. GNSS Applications for Road
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9. Galileo key for GNSS Road Applications
Because of the major consequences of errrors, both liability critical and safety critical applications require position integrity, i.e. ensuring that errors are below certain threshold.
Galileo (and EGNOS), unlike GPS, provides signal integrity.
Galileo (and EGNOS) are key enablers for new Road applications.
Why integrity is important instead of accuracy?
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10. Integrity vs. Accuracy: Example
High Accuracy but no Integrity
Low Accuracy but with Integrity
20cm
10cm
8 cm
18 cm
Accuracy (e.g. error at 95%)
Integrity is what will enable us to use GNSS positioning for liability critical applications.
99%
100%
Integrity (percentage inside the yellow circle)
Would you rely on the more accurate knife thrower?
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11. Integrity Performance Characterised by:
Position Integrity
Estimated
Position
Protection
Level
Error
Real
Practical Implementation ->Protection Levels: “a circle around the estimated position where the real position is guaranteed to be with a very high probability”
Integrity Performance Characterised by:
The Size of the Protection Level
The Time To Alarm (TTA): maximum time to let the user known that the error exceeded the Protection Level
The Integrity Risk: probability that the real position is out of the Protection Level (without informing the user)
But how is in practice position integrity implemented?
Through the definition and computation of the so called protection levels. They represent a circle around the estimated position within which the real poistion is guranteed to be with a very high probbaility. I.e. The probability that ths real position is out of the PL is extremely low.
Position errors are caused by errors in the signal (such as saellite clock errors and propagation erros) but also by local errors such as multipath.
Galileo (and EGNOS) integrity allow to bound the first set of errors but local errors are out of the control of the system.
Position integrity is then more than signal integrity what imples that new reciever capabilities have to be developed to really ensure position integrity by bounding local errors.
50 sec
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12. Emergency Services Requirements
Most
Demanding
10-10
10-8
Galileo SoL
Capabilities
Integrity Risk
10-6
Less
Demanding
10-4
10-2
0.1
0.1 1 1
Emergency Services (as liability critical) are feasible
with Galileo SoL/CS
TTA (sec) 10
Protection Levels
(m) 10
100
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13. 10-10 10-8 Integrity Risk 10-6 10-4 10-2 0.1 0.1 1 TTA (sec) 1
ADAS Requirements
ADAS (control)
Requirements
10-10
10-8
Galileo SoL
Capabilities
Integrity Risk
10-6
10-4
Technology
Improvement
(e.g. TCAR)
10-2
0.1
0.1 1 1
TTA (sec) 10
ADAS (GNSS in the driving loop) requirements are still
far from Galileo Capabilities
Protection Levels
(m) 10
100
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14. Conclusions
Galileo in the future (and EGNOS now) open the door to new Road Applications
Liability and Saftey critical ones are the best examples of those new applications
Galileo (and EGNOS) performance well cover Liability Critical and Emergency Service Requirements and then Galileo contributes to increase the road safety
ADAS based on GNSS still immature as required performance and complexity are still far from Galileo system capabilities
In all those applications Position Integrity is the key and then EGNOS and Galileo become enablers
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