Integrity Monitoring: From Airborne to Land Applications

Safety-critical applications in transportation require GNSS-based positioning with high levels of continuity, accuracy and integrity. The system needs to detect and exclude faults and to raise an alarm in the event of unsafe positioning. This capability is referred to as integrity monitoring (IM). While IM was considered until recently only in aviation, it is currently a key performance parameter in land applications, such as Intelligent Transport Systems (ITS). In this chapter the IM concepts, models and methods developed so far are compared. In particular, Fault Detection and Exclusion (FDE) and bounding of positioning errors methods borrowed from aviation (i.e. Weighted RAIM and ARAIM) are discussed in detail, in view of their possible adoption for land applications. Their strengths and limitations, and the modifications needed for application in the different context are highlighted. A practical demonstration of IM in ITS is presented

Cross Domain IW Threats to SOF Maritime Missions: Implications for U.S. SOF

As cyber vulnerabilities proliferate with the expansion of connected devices, wherein security is often forsaken for ease of use, Special Operations Forces (SOF) cannot escape the obvious, massive risk that they are assuming by incorporating emerging technologies into their toolkits. This is especially true in the maritime sector where SOF operates nearshore in littoral zones. As SOF—in support to the U.S. Navy— increasingly operate in these contested maritime environments, they will gradually encounter more hostile actors looking to exploit digital vulnerabilities. As such, this monograph comes at a perfect time as the world becomes more interconnected but also more vulnerable

Satellite technology : reinforcement of computer data transmission technology : implications for the maritime world communications, data transfer and maritime education

This dissertation is a study of the impact of data transmission via satellite on the maritime world of communication, data transfer and education. The aim of the study is to understand the technological reinforcement of the maritime industry and the changes taking place in it. With the avalanche of changes that are taking place in the field of information technology, they can be used to facilitate the shipping industry. This dissertation assists in understanding some of the technological evolution of satellite technology and data communication and in the needs of the maritime industry as well. This dissertation describes satellite technology and data communication and analyses the data communication software (protocols), compression software, and other application software combinations with maritime communication system provided to improve ship operation and management for safety. The conclusion and recommendations chapter examines the implications of the technology changes on developing countries, the need to be harmonised in training and education for the maritime industry, maritime communication systems and the equipment, policy of shipping companies and communication costs

Performance of Receiver Autonomous Integrity Monitoring (RAIM) for Maritime Operations

The use of GNSS in the context of maritime applications has evolved during the past. The International Maritime Organization (IMO) has defined and published requirements for those applications. Comparing the requirements on the one hand specified by ICAO and on the other hand by IMO, significant differences get obvious. A major focus is on the evaluation of the performance of the integrity algorithms. Also concept drivers are discussed

Adaptive, reliable, and accurate positioning model for location-based services

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This thesis presents a new strategy in achieving highly reliable and accurate position solutions fulfilling the requirements of Location-Based Services (LBS) pedestrians’ applications. The new strategy is divided into two main parts. The first part integrates the available positioning technology within the surrounding LBS application context by introducing an adaptive LBS framework. The context can be described as a group of factors affecting the application behaviour; this includes environmental states, available resources and user preferences. The proposed adaptive framework consists of several stages, such as defining the contextual factors that have a direct effect on the positioning performance, identifying preliminary positioning performance requirements associated with different LBS application groups, and introducing an intelligent positioning services selection function. The second part of this work involves the design and development of a novel positioning model that is responsible for delivering highly reliable, accurate and precise position solutions to LBS users. This new model is based on the single frequency GPS Standard Positioning Service (SPS). Additionally, it is incorporated within the adaptive LBS framework while providing the position solutions, in which all identified contextual factors and application requirements are accounted. The positioning model operates over a client-server architecture including two main components, described as the Localisation Server (LS) and the Mobile Unit (MU). Hybrid functional approaches were developed at both components consisting of several processing procedures allowing the positioning model to operate in two position determination modes. Stand-alone mode is used if enough navigation information was available at the MU using its local positioning device (GPS/EGNOS receiver). Otherwise, server-based mode is utilised, in which the LS intervenes and starts providing the required position solutions. At the LS, multiple sources of GPS augmentation services were received using the Internet as the sole augmentation data transportation medium. The augmentation data was then processed and integrated for the purpose of guaranteeing the availability of valid and reliable information required for the provision of accurate and precise position solutions. Two main advanced position computation methods were developed at the LS, described as coordinate domain and raw domain. The positioning model was experimentally evaluated. According to the reported results, the LS through the developed position computation methods, was able to provide position samples with an accuracy of less than 2 meters, with high precision at 95% confidence level; this was achieved in urban, rural, and open space (clear satellite view) navigation environments. Additionally, the integrity of the position solutions was guaranteed in such environments during more than 90% of the navigation time, taking into consideration the identified integrity thresholds (Horizontal Alert Limits (HAL)=11 m). This positioning performance has outperformed the existing GPS/EGNOS service which was implemented at the MU in all scenarios and environments. In addition, utilising a simulation evaluation facility the developed positioning model performance was quantified with reference to a hybrid positioning service that will be offered by future Galileo Open Service (OS) along with GPS/EGNOS. Using the statistical t-test, it was concluded that there is no significant difference in terms of the position samples’ accuracy achieved from the developed positioning model and the hybrid system at a particular navigation environment described as rural area. The p-value was 0.08 and the level of significance used was 0.05. However, a significant difference in terms of the service integrity for the advantage of the hybrid system was experienced in all remaining scenarios and environments more especially the urban areas due to surrounding obstacles and conditions

A safety assessment framework for Automatic Dependent Surveillance Broadcast (ADS-B) and its potential impact on aviation safety

The limitations of the current civil aviation surveillance systems include a lack of coverage in some areas and low performance in terms of accuracy, integrity, continuity and availability particularly in high density traffic areas including airports, with a negative impact on capacity and safety. Automatic Dependent Surveillance Broadcast (ADS-B) technology has been proposed to address these limitations by enabling improved situational awareness for all stakeholders and enhanced airborne and ground surveillance, resulting in increased safety and capacity. In particular, its scalability and adaptability should facilitate its use in general aviation and in ground vehicles. This should, in principle, provide affordable, effective surveillance of all air and ground traffic, even on airport taxiways and runways, and in airspace where radar is ineffective or unavailable. The success of the progressive implementation of ADS-B has led to numerous programmes for its introduction in other parts of the World where the operational environment is considerably different from that of Australia. However, a number of critical issues must be addressed in order to benefit from ADS-B, including the development and execution of a safety case that addresses both its introduction into legacy and new systems’ operational concepts, the latter including the Single European Sky (SES) / Single European Sky ATM Research (SESAR) and the US’ Next Generation Air Transportation System (NexGEN). This requires amongst others, a good understanding of the limitations of existing surveillance systems, ADS-B architecture and system failures and its interfaces to the existing and future ATM systems. Research on ADS-B to date has not addressed in detail the important questions of limitations of existing systems and ADS-B failure modes including their characterisation, modelling and assessment of impact. The latter is particularly important due to the sole dependency of ADS-B on GNSS for information on aircraft state and its reliance on communication technologies such as Mode-S Extended Squitter, VHF Data Link Mode-4 (VDLM4) or Universal Access Transceiver (UAT), to broadcast the surveillance information to ground-based air traffic control (ATC) and other ADS-B equipped aircraft within a specified range, all of which increase complexity and the potential for failures. This thesis proposes a novel framework for the assessment of the ADS-B system performance to meet the level of safety required for ground and airborne surveillance operations. The framework integrates various methods for ADS-B performance assessment in terms of accuracy, integrity, continuity, availability and latency, and reliability assessment using probabilistic safety assessment methods; customized failure mode identification approach and fault tree analysis. Based on the framework, the thesis develops a failure mode register for ADS-B, identifies and quantifies the impact of a number of potential hazards for the ADS-B. Furthermore, this thesis identifies various anomalies in the onboard GNSS system that feeds aircraft navigation information into the ADS-B system. Finally, the thesis maps the ADS-B data availability and the quantified system performance to the envisioned airborne surveillance application’s requirements. The mapping exercise indicates that, the quantified ADS-B accuracy is sufficient for all applications while ADS-B integrity is insufficient to support the most stringent application: Airborne Separation (ASEP). In addition, some of the required performance parameters are unavailable from aircraft certified to DO-260 standard. Therefore, all aircraft must be certified to DO-260B standard to support the applications and perform continuous monitoring, to ensure consistency in the system performance of each aircraft.Open Acces

Open Platforms for Connected Vehicles

L'abstract è presente nell'allegato / the abstract is in the attachmen

Satellite technology in the maritime world : applications and implications

This dissertation is a study of the widespread utilization of satellite technology in the maritime world, with particular reference to the applications and implications of communication, navigation and remote sensing satellites to shipping and other maritime related fields. A brief look is taken at the general background of satellite technology, including the growth and development and basic techniques as well as categorization of applications. This is followed by a more detailed view of the three different areas of the applications of satellite technology, namely maritime communications, marine navigation and maritime meteorology and oceanography. The two well-known satellite-based systems, the INMARSAT System and the Global Positioning System, are both widely used by the maritime community and thus emphasized in this study. Apart from a brief description of those two systems, their applications are examined, their impact on the marine industry is discussed and their future development is investigated in order to obtain an appreciation of their role in the present maritime world. The applications of remote sensing satellites in marine meteorology and oceanography are also discussed. In addition to the above, the impact of the increasing use of satellite technology on maritime education and training is investigated. The concluding chapter is a summary of the main points discussed in the core chapters, which reflect the author’s viewpoin

System elements required to guarantee the reliability, availability and integrity of decision-making information in a complex airborne autonomous system

Current air traffic management systems are centred on piloted aircraft, in which all the main decisions are made by humans. In the world of autonomous vehicles, there will be a driving need for decisions to be made by the system rather than by humans due to the benefits of more automation such as reducing the likelihood of human error, handling more air traffic in national airspace safely, providing prior warnings of potential conflicts etc. The system will have to decide on courses of action that will have highly safety critical consequences. One way to ensure these decisions are robust is to guarantee that the information being used for the decision is valid and of very high integrity. [Continues.