The Feasibility of R-Mode to Meet Resilient PNT Requirements for e-Navigation

Position, Navigation, and Timing (PNT) is part of the critical infrastructure necessary for the safety and efficient of vessel movements, especially in congested areas such as the North Sea. GNSS (primarily GPS and GLONASS) has become the primary PNT source for maritime operations. The GNSS position is used both for vessel navigation and as the position source for AIS. Unfortunately, GNSS is vulnerable to jamming and interference – not intentional and unintentional. This can lead to the loss of positioning information or even worse, to incorrect positioning information. The user requirement is for dependable PNT information at all times, even under GNSS jamming conditions. One potential source of resilient PNT services is Ranging Mode (R-Mode) using signals independent of GNSS. The German Federal Waterways and Shipping Administration has contracted for a feasibility study of R-mode using MF-DGNSS and VHF AIS signals as well as those signals in combination and in combination with eLoran. The first part of the study focused on the feasibility of using MF-DGNSS signals for ranging and timing. It examined the state of the art, identified potential solution methods, and, after examining Pros and Cons of the various options, selected a few options for further study. Part 2 examined the proposed solutions in depth and identified the modifications required for both the reference stations (transmitters) and user equipment (beacon receivers). Part 3 and 4 of the study repeated Parts 1 and 2, but using AIS signals rather than MF. Part 4 of the study examined the possibility of combining MF and AIS R-mode or combining MF R-Mode and eLoran. This paper presents the results of this study including recommended R-Mode implementations and bounds on the positioning performance using the various R-Mode methods. Included are predictions of DGNSS and AIS R-Mode coverage and the resulting HDOP using existing and preposed DGNSS and AUS sites with specific detail in the area of the planned test bed in the North Sea

The impact of new signals on precise marine navigation - initial results from an experiment in Harwich Harbour

The General Lighthouse Authorities of the United Kingdom and Ireland (GLAs) are supporting a project at University College London (UCL) to study whether it is possible to meet the International Maritime Organisation’s (IMO) future requirements for port and harbour approach using future GNSS constellations, as detailed in IMO resolution A.915. This paper presents the results of a trial focusing on the accuracy, integrity, availability and continuity of port navigation, port approach, and docking. Abstract The required accuracy for docking is 0.1 m (95\%), which currently necessitates the use of Real Time Kinematic (RTK) processing. We consider the single-epoch geometry-based approach, which is robust against loss of lock and will fully benefit from the additional satellites. The trial was held at the beginning of May 2008 and saw THV Alert navigate into Harwich Harbour while satellite observation data were recorded from the vessel and from shore-based reference stations. Additional data were obtained from nearby Ordnance Survey reference stations, and two total stations were used to track the vessel’s passage to provide a truth model. Several modernised GPS satellites were tracked. The data were processed under different scenarios, using software developed at UCL, and the positioning performance analysed. Abstract Providing integrity for single-epoch RTK is particularly difficult. The identification of phase observation outliers is not possible before the integer ambiguities are resolved, but an undetected outlier could prevent successful ambiguity resolution. However, it will not always be necessary to fix every ambiguity to achieve the required precision, particularly with a multi-GNSS constellation. This paper introduces a new algorithm for partial ambiguity resolution in the presence of measurement bias that has been developed and tested at UCL.  This algorithm results in an improved ambiguity resolution success rate at the expense of computation time

Hybrid Satellite-Terrestrial Communication Networks for the Maritime Internet of Things: Key Technologies, Opportunities, and Challenges

With the rapid development of marine activities, there has been an increasing number of maritime mobile terminals, as well as a growing demand for high-speed and ultra-reliable maritime communications to keep them connected. Traditionally, the maritime Internet of Things (IoT) is enabled by maritime satellites. However, satellites are seriously restricted by their high latency and relatively low data rate. As an alternative, shore & island-based base stations (BSs) can be built to extend the coverage of terrestrial networks using fourth-generation (4G), fifth-generation (5G), and beyond 5G services. Unmanned aerial vehicles can also be exploited to serve as aerial maritime BSs. Despite of all these approaches, there are still open issues for an efficient maritime communication network (MCN). For example, due to the complicated electromagnetic propagation environment, the limited geometrically available BS sites, and rigorous service demands from mission-critical applications, conventional communication and networking theories and methods should be tailored for maritime scenarios. Towards this end, we provide a survey on the demand for maritime communications, the state-of-the-art MCNs, and key technologies for enhancing transmission efficiency, extending network coverage, and provisioning maritime-specific services. Future challenges in developing an environment-aware, service-driven, and integrated satellite-air-ground MCN to be smart enough to utilize external auxiliary information, e.g., sea state and atmosphere conditions, are also discussed

Impact of Spoofing of Navigation Systems on Maritime Situational Awareness

The development of contemporary navigation and positioning systems have significantly improved reliability and speeds in maritime navigation. At the same time, the vulnerabilities of these systems to cyber threats represent a remarkable issue to the safety of navigation. Therefore, the maritime community has raised the question of cybersecurity of navigation systems in recent years. This paper aims to analyse the vulnerabilities of the Global Navigation Satellite System (GNSS), Electronic Chart Display Information System (ECDIS) and Automatic Identification System (AIS). The concepts of these systems were developed at a time when cybersecurity issues have not been among the top priorities. Open broadcasts, the absence of or limited existence of data encryption and authentication can be considered as their primary security weaknesses. Therefore, these systems are vulnerable to cyber-attacks. The GPS as the data source of a ship’s position can relatively easily be jammed and/or spoofed, increasing the vulnerabilities of ECDIS and AIS. A systematic literature review was conducted for this article, supplemented by a SWOT analysis of the AIS service and particular case studies of recent cyber-attacks on these systems. The analysis of selected case studies confirmed that these systems could easily be spoofed and become a subject of data manipulation with significant consequences for the safety of navigation. The paper provides conclusions and recommendations highlighting the necessity for the users to be aware of the vulnerabilities of modern navigation systems

Research on Impulse Radio Ultra - wideband Positioning Method Based on Combined BP Neural Network and SVM

Intelligent tour guide is a comprehensive service based on tourist\u27s location, which is closely related to Geographic Information System (GIS), mobile positioning technology and Location-Based Service (LBS). But the intelligent tour guide field urgently needs the integrated positioning and navigation technology inside and outside the room. IR-UWB technology is suitable for positioning, tracking, navigation and communication in complex indoor environment, and is considered as the most potential indoor positioning technology to realize seamless connection between indoor and outdoor with outdoor positioning technologies such as GPS. However, one of the main problems facing IR-UWB positioning is Non-Line-Of-Sight (NLOS) error. Based on the advantages of BP neural network and support vector machine, this paper proposes a multi-model fusion algorithm to mitigate the NLOS propagation error of the time difference of arrival (TDOA) and the angle of arrival (AOA) of IR-UWB signal, and then uses TDOA/AOA hybrid positioning that mitigates the NLOS error. Simulation results show that the combined algorithm has stronger NLOS resistance and higher positioning accuracy than the single machine learning algorithm in mitigation NLOS errors

A feasibility study: Forest Fire Advanced System Technology (FFAST)

The National Aeronautics and Space Administration/Jet Propulsion Laboratory and the United States Department of Agriculture Forest Service completed a feasibility study that examined the potential uses of advanced technology in forest fires mapping and detection. The current and future (1990's) information needs in forest fire management were determined through interviews. Analysis shows that integrated information gathering and processing is needed. The emerging technologies that were surveyed and identified as possible candidates for use in an end to end system include ""push broom'' sensor arrays, automatic georeferencing, satellite communication links, near real or real time image processing, and data integration. Matching the user requirements and the technologies yielded a ""strawman'' system configuration. The feasibility study recommends and outlines the implementation of the next phase for this project, a two year, conceptual design phase to define a system that warrants continued development

A Portuguese Case Study

There is a high national dependency on Position, Navigation and Timing (PNT) Systems for several individuals, services and organisations that depend on this information on a daily basis. Those who rely on precise, accurate and continuous information need to have resilient systems in order to be highly efficient and reliable. A resilient structure and constantly available systems makes it easier to predict a threat or rapidly recover in a hazardous environment. One of these organisations is the Portuguese Navy, whose main purposes are to combat and maintain maritime safety. In combat, resilient PNT systems are needed for providing robustness in case of any threat or even a simple occasional system failure. In order to guarantee maritime safety, for example in Search and Rescue Missions, the need of PNT information is constant and indispensable for positioning control. The large diversity of PNT-dependent equipment, developed over the last two decades, is a valid showcase for the high GPS dependency that is seen nowadays – which is vulnerable to various factors like interference, jamming, spoofing and ionospheric conditions. The recent interest over integrated PNT system resolutions is related to the search for redundancy, accuracy, precision, availability, low cost, coverage, reliability and continuity. This study aimed to build a current PNT Portuguese picture based on Stakeholder Analysis and Interviews; assess the vulnerability of those who depend mainly on GPS for PNT information and, find out what the next steps should be in order to create a National PNT Strategy.Existe uma elevada dependência nacional em sistemas de Posição, Navegação e Tempo (PNT) por parte de diversos indivíduos, serviços e organizações que dependem desta informação no seu dia-a-dia. Todos os que dependem de informação precisa, exata e contínua, necessitam de ter sistemas resilientes para que sejam altamente eficientes e fiáveis. Uma estrutura resiliente e sistemas continuamente disponíveis facilitam a previsão de possíveis ameaças ou a expedita recuperação da funcionalidade, em ambientes hostis. Uma destas organizações é a Marinha Portuguesa cujas funções principais são o combate, a salvaguarda da vida humana no mar e a segurança marítima e da navegação. Para o combate, são necessários sistemas PNT, resilientes, que ofereçam robustez em caso de uma simples ameaça ou falha temporária dos sistemas. Por forma a ser possível cumprir a missão, a necessidade de ter informação PNT, fidedigna e atualizada, é constante e indispensável para o controlo preciso e exato da posição. Uma unidade naval, por forma a permanecer continuamente no mar, manter a sua prontidão, treinar a sua guarnição ou ser empenhada num cenário de guerra, necessita de saber, com confiança e sem erros, a sua posição e referência de tempo. A grande diversidade de sistemas dependentes de informação PNT, desenvolveu-se em larga escala nas últimas duas décadas e sustenta cada vez mais a alta dependência do GPS, que é vulnerável a diversas fontes de erro, tais como interferência, empastelamento, mistificação e condições ionosféricas. Atualmente, o elevado interesse na criação de sistemas PNT integrados está associado à procura da redundância, exatidão, precisão, disponibilidade, baixo custo, cobertura, fiabilidade e continuidade. Este estudo teve como objetivos construir o panorama atual, em Portugal, ao nível dos Sistemas PNT, baseando-se numa análise de Stakeholders e entrevistas; avaliar a vulnerabilidade de organizações e serviços que dependam exclusivamente do GPS como fonte de informação PNT; e propor um possível caminho para que seja possível criar uma Estratégia PNT Naciona