79 research outputs found
Mobile node-aided localization and tracking in terrestrial and underwater networks
In large-scale wireless sensor networks (WSNs), the position information of individual
sensors is very important for many applications. Generally, there are a small number
of position-aware nodes, referred to as the anchors. Every other node can estimate its
distances to the surrounding anchors, and then employ trilateration or triangulation for
self-localization. Such a system is easy to implement, and thus popular for both terrestrial
and underwater applications, but it suffers from some major drawbacks. First, the density
of the anchors is generally very low due to economical considerations, leading to poor
localization accuracy. Secondly, the energy and bandwidth consumptions of such systems
are quite significant. Last but not the least, the scalability of a network based on fixed
anchors is not good. Therefore, whenever the network expands, more anchors should be
deployed to guarantee the required performance. Apart from these general challenges,
both terrestrial and underwater networks have their own specific ones. For example, realtime
channel parameters are generally required for localization in terrestrial WSNs. For
underwater networks, the clock skew between the target sensor and the anchors must
be considered. That is to say, time synchronization should be performed together with
localization, which makes the problem complicated.
An alternative approach is to employ mobile anchors to replace the fixed ones. For
terrestrial networks, commercial drones and unmanned aerial vehicles (UAVs) are very
good choices, while autonomous underwater vehicles (AUVs) can be used for underwater
applications. Mobile anchors can move along a predefined trajectory and broadcast beacon
signals. By listening to the messages, the other nodes in the network can localize themselves
passively. This architecture has three major advantages: first, energy and bandwidth consumptions can be significantly reduced; secondly, the localization accuracy can be much
improved with the increased number of virtual anchors, which can be boosted at negligible
cost; thirdly, the coverage can be easily extended, which makes the solution and the network
highly scalable.
Motivated by this idea, this thesis investigates the mobile node-aided localization and
tracking in large-scale WSNs. For both terrestrial and underwater WSNs, the system
design, modeling, and performance analyses will be presented for various applications,
including: (1) the drone-assisted localization in terrestrial networks; (2) the ToA-based
underwater localization and time synchronization; (3) the Doppler-based underwater localization;
(4) the underwater target detection and tracking based on the convolutional
neural network and the fractional Fourier transform. In these applications, different challenges
will present, and we will see how these challenges can be addressed by replacing
the fixed anchors with mobile ones. Detailed mathematical models will be presented, and
extensive simulation and experimental results will be provided to verify the theoretical
results. Also, we will investigate the channel estimation for the fifth generation (5G) wireless
communications. A pilot decontamination method will be presented for the massive
multiple-input-multiple-output communications, and the data-aided channel tracking will
be discussed for millimeter wave communications. We will see that the localization problem
is highly coupled with the channel estimation in wireless communications
Posicionamento cooperativo para redes sem fios heterogéneas
Doutoramento em Engenharia ElectrotécnicaFuture emerging market trends head towards positioning based services
placing a new perspective on the way we obtain and exploit positioning
information. On one hand, innovations in information technology and
wireless communication systems enabled the development of numerous
location based applications such as vehicle navigation and tracking,
sensor networks applications, home automation, asset management,
security and context aware location services. On the other hand, wireless
networks themselves may bene t from localization information to
improve the performances of di erent network layers. Location based
routing, synchronization, interference cancellation are prime examples
of applications where location information can be useful.
Typical positioning solutions rely on measurements and exploitation of
distance dependent signal metrics, such as the received signal strength,
time of arrival or angle of arrival. They are cheaper and easier to implement
than the dedicated positioning systems based on ngerprinting,
but at the cost of accuracy. Therefore intelligent localization algorithms
and signal processing techniques have to be applied to mitigate
the lack of accuracy in distance estimates. Cooperation between nodes
is used in cases where conventional positioning techniques do not perform
well due to lack of existing infrastructure, or obstructed indoor
environment. The objective is to concentrate on hybrid architecture
where some nodes have points of attachment to an infrastructure, and
simultaneously are interconnected via short-range ad hoc links. The
availability of more capable handsets enables more innovative scenarios
that take advantage of multiple radio access networks as well as
peer-to-peer links for positioning.
Link selection is used to optimize the tradeo between the power consumption
of participating nodes and the quality of target localization.
The Geometric Dilution of Precision and the Cramer-Rao Lower Bound
can be used as criteria for choosing the appropriate set of anchor nodes
and corresponding measurements before attempting location estimation
itself. This work analyzes the existing solutions for node selection
in order to improve localization performance, and proposes a novel
method based on utility functions. The proposed method is then extended
to mobile and heterogeneous environments. Simulations have
been carried out, as well as evaluation with real measurement data. In
addition, some speci c cases have been considered, such as localization
in ill-conditioned scenarios and the use of negative information.
The proposed approaches have shown to enhance estimation accuracy,
whilst signi cantly reducing complexity, power consumption and signalling
overhead.As tendências nos mercados emergentes caminham na direção dos serviços baseados em posicionamento, criando uma nova perspectiva na forma como podemos obter e utilizar informação de posicionamento.
Por um lado, as inovações em tecnologias da informação e sistemas de comunicação sem fios permitiram o desenvolvimento de inĂşmeras aplicações baseadas em localização, tais como a navegação e monitorização de veĂculo, aplicações de redes de sensores, domĂłtica, gestĂŁo de ativos, segurança e serviços de localização sensĂveis ao contexto. Por outro lado, as prĂłprias redes sem fios podem beneficiar da informação de localização dos utilizadores de forma a melhorarem as performances de diferentes camadas de rede. Routing baseado em localização, sincronização e cancelamento de interferĂŞncia sĂŁo os exemplos mais representativos de áreas onde a informação de localização pode ser Ăştil.
Soluções de localização tĂpicas dependem de medições e de aproveitamento de mĂ©tricas de sinal dependentes da distância, tais como a potĂŞncia do sinal recebido, o tempo ou ângulo de chegada. SĂŁo mais baratos e fáceis de implementar do que sistemas de localização dedicados com base em fingerprinting, com a desvantagem da perda de precisĂŁo. Consequentemente, algoritmos inteligentes de localização e tĂ©cnicas de processamento de sinal tĂŞm de ser aplicados para compensar a falta de precisĂŁo das estimativas de distância. A cooperação entre nodos Ă© usada nos casos em que as tĂ©cnicas convencionais de posicionamento nĂŁo tĂŞm um bom desempenho devido Ă inexistĂŞncia de infraestrutura adequada, ou a um ambiente interior com obstruções.
O objetivo Ă© ter uma arquitetura hĂbrida, onde alguns nĂłs tĂŞm pontos de ligação a uma infraestrutura e simultaneamente estĂŁo interligados atravĂ©s ligações ad-hoc de curto alcance. A disponibilidade de equipamentos mais capazes permite cenários mais inovadores que tiram proveito de mĂşltiplas redes de acesso de rádio, bem como ligações peer-to-peer, para o posicionamento.
A seleção de ligações Ă© usada para otimizar o equilĂbrio entre o consumo
de energia dos nós participantes e da qualidade da localização do alvo. A diluição geométrica de precisão e a Cramér Rao Lower Bound podem ser utilizadas como critrio para a escolha do conjunto adequado de nodos de ancoragem e as medições correspondentes antes de realizar a tarefa de estimativa de localizaçãoo. Este trabalho analisa as soluções existentes para a seleção de nós, a fim de melhorar o desempenho de localização e propõe um novo método baseado em funções de utilidade.
O mĂ©todo proposto Ă© entĂŁo estendido para ambientes mĂłveis e heterogĂ©neos. Foram realizadas simulações bem como avaliação de dados de medições reais. AlĂ©m disso, alguns casos especĂficos foram considerados, tais como a localização em cenários mal-acondicionados e uso de informação negativa. As abordagens propostas revelaram uma melhoria na precisĂŁo da estimação, ao mesmo tempo que reduziram significativamente a complexidade do cálculo, o consumo de energia e o overhead do sinal
Toward UWB Impulse Radio Sensing: Fundamentals, Potentials, and Challenges
Radio sensing is a rapidly emerging research field. It focuses on designing an integrated communication system that can also perform localization and radar functionalities sharing the same transmit signals and potentially the same hardware. Ultra-wideband (UWB) impulse radio is a promising technology for radio sensing because it offers a high-range resolution and direct access to the channel impulse response (CIR) to observe the multipath components (MPCs) of the wideband channel caused by scattering at target objects. This approach enables a wide range of functionalities and applications, especially in the field of mobility and transportation. The foundation is given by the signal propagation and channel modeling of the UWB channel, which is briefly revisited in this chapter. Based on the CIR and estimated MPCs the target object can be localized like a multistatic passive radar. The influence of geometry in a passive target localization system is studied by calculating the geometric dilution of precision (GDOP). In addition to passive localization more tasks and functionalities of radio sensing, are briefly introduced including detection, tracking, imaging, counting, and classification. The chapter concludes with further research directions and challenges in UWB radio sensing, especially for real-world use in the context of mobility applications
Self-organising an indoor location system using a paintable amorphous computer
This thesis investigates new methods for self-organising a precisely defined pattern of intertwined number sequences which may be used in the rapid deployment of a passive indoor positioning system's infrastructure.A future hypothetical scenario is used where computing particles are suspended in paint and covered over a ceiling. A spatial pattern is then formed over the covered ceiling. Any small portion of the spatial pattern may be decoded, by a simple camera equipped device, to provide a unique location to support location-aware pervasive computing applications.Such a pattern is established from the interactions of many thousands of locally connected computing particles that are disseminated randomly and densely over a surface, such as a ceiling. Each particle has initially no knowledge of its location
or network topology and shares no synchronous clock or memory with any other particle.The challenge addressed within this thesis is how such a network of computing particles that begin in such an initial state of disarray and ignorance can, without outside intervention or expensive equipment, collaborate to create a relative coordinate system. It shows how the coordinate system can be created to be coherent, even in the face of obstacles, and closely represent the actual shape of the networked surface itself. The precision errors incurred during the propagation of the coordinate system are identified and the distributed algorithms used to avoid this error are explained and demonstrated through simulation.A new perimeter detection algorithm is proposed that discovers network edges and other obstacles without the use of any existing location knowledge. A new distributed localisation algorithm is demonstrated to propagate a relative coordinate system throughout the network and remain free of the error introduced by the network perimeter that is normally seen in non-convex networks. This localisation algorithm operates without prior configuration or calibration, allowing the coordinate system to be deployed without expert manual intervention or on networks that are otherwise inaccessible.The painted ceiling's spatial pattern, when based on the proposed localisation algorithm, is discussed in the context of an indoor positioning system
An Assessment on the Use of Stationary Vehicles as a Support to Cooperative Positioning
In this paper, we consider the use of stationary vehicles as tools to enhance
the localisation capabilities of moving vehicles in a VANET. We examine the
idea in terms of its potential benefits, technical requirements, algorithmic
design and experimental evaluation. Simulation results are given to illustrate
the efficacy of the technique.Comment: This version of the paper is an updated version of the initial
submission, where some initial comments of reviewers have been taken into
accoun
Recent Advances in Indoor Localization Systems and Technologies
Despite the enormous technical progress seen in the past few years, the maturity of indoor localization technologies has not yet reached the level of GNSS solutions. The 23 selected papers in this book present the recent advances and new developments in indoor localization systems and technologies, propose novel or improved methods with increased performance, provide insight into various aspects of quality control, and also introduce some unorthodox positioning methods
Localization Context-Aware Models for Wireless Sensor Network
Wireless sensor networks (WSNs) are emerging as the key technology to support the Internet of Things (IoT) and smart objects. Small devices with low energy consumption and limited computing resources have wide use in many applications and different fields. Nodes are deployed randomly without a priori knowledge of their location. However, location context is a fundamental feature necessary to provide a context-aware framework to information gathered from sensors in many services such as intrusion detection, surveillance, geographic routing/forwarding, and coverage area management. Nevertheless, only a little number of nodes called anchors are equipped with localization components, such as Global Positioning System (GPS) chips. Worse still, when sensors are deployed in an indoor environment, GPS serves no purpose. This chapter surveys a variety of state-of-the-art existing localization techniques and compares their characteristics by detailing their applications, strengths, and challenges. The specificities and enhancements of the most popular and effective techniques are as well reported. Besides, current research directions in localization are discussed
Recent Advances in Indoor Localization: A Survey on Theoretical Approaches and Applications
Nowadays, the availability of the location information becomes a key factor in today’s communications systems for allowing location based services. In outdoor scenarios, the Mobile Terminal (MT) position is obtained with high accuracy thanks to the Global Positioning System (GPS) or to the standalone cellular systems. However, the main problem of GPS or cellular systems resides in the indoor environment and in scenarios with deep shadowing effect where the satellite or cellular signals are broken. In this paper, we will present a review over different technologies and concepts used to improve indoor localization. Additionally, we will discuss different applications based on different localization approaches. Finally, comprehensive challenges in terms of accuracy, cost, complexity, security, scalability, etc. are presente
Localisation in wireless sensor networks for disaster recovery and rescuing in built environments
A thesis submitted to the University of Bedfordshire in partial fulfilment of the requirements for the degree of Doctor of PhilosophyProgress in micro-electromechanical systems (MEMS) and radio frequency (RF) technology has fostered the development of wireless sensor networks (WSNs). Different from traditional networks, WSNs are data-centric, self-configuring and self-healing. Although WSNs have been successfully applied in built environments (e.g. security and services in smart homes), their applications and benefits have not been fully explored in areas such as disaster recovery and rescuing. There are issues related to self-localisation as well as practical constraints to be taken into account.
The current state-of-the art communication technologies used in disaster scenarios are challenged by various limitations (e.g. the uncertainty of RSS). Localisation in WSNs (location sensing) is a challenging problem, especially in disaster environments and there is a need for technological developments in order to cater to disaster conditions. This research seeks to design and develop novel localisation algorithms using WSNs to overcome the limitations in existing techniques. A novel probabilistic fuzzy logic based range-free localisation algorithm (PFRL) is devised to solve localisation problems for WSNs. Simulation results show that the proposed algorithm performs better than other range free localisation algorithms (namely DVhop localisation, Centroid localisation and Amorphous localisation) in terms of localisation accuracy by 15-30% with various numbers of anchors and degrees of radio propagation irregularity.
In disaster scenarios, for example, if WSNs are applied to sense fire hazards in building, wireless sensor nodes will be equipped on different floors. To this end, PFRL has been extended to solve sensor localisation problems in 3D space. Computational results show that the 3D localisation algorithm provides better localisation accuracy when varying the system parameters with different communication/deployment models. PFRL is further developed by applying dynamic distance measurement updates among the moving sensors in a disaster environment. Simulation results indicate that the new method scales very well
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