GPS Availability Research Articles

Critical Analysis of Distributed Localization Algorithms for Wireless Sensor Networks

In the past decade, Wireless sensor networks (WSNs) have attracted very much attention from the research and industrial community. Various WSN based projects produced fruitful and interesting results. In various applications, the location information of node is vital for the service. The reason is that users usually need to know what happens, but also where the concerned events happen. For example, in battlefield surveillance, the knowledge of where the enemy comes from can be much more important than only knowing the appearance of the enemy, it is much important that sensors reports the information along with their location. Localization is one of the primary and widely useful middle-ware services in sensor networks, mostly allows every node to obtain its location information. The localization schemes can be categorized on the basis of various parameters like availability of GPS, presence of anchors, range measurements, model of computation etc. On the basis of computation model, the localization approaches can be categorized into: centralized and distributed localization techniques. Due to certain advantages, distributed localization is flattering as an active stem in sensor localization. In this paper, we have been reported a detailed analysis on distributed localization techniques and outline the merits and limitations of distributed localization schemes in WSNs. Finally, we conclude the paper with some open issues.

IODetector

The location and context switching, especially the indoor/outdoor switching, provides essential and primitive information for upper-layer mobile applications. In this article, we present IODetector: a lightweight sensing service that runs on the mobile phone and detects the indoor/outdoor environment in a fast, accurate, and efficient manner. Constrained by the energy budget, IODetector primarily leverages lightweight sensing resources, such as light sensors, magnetism sensors, and cell tower signals. For universal applicability, IODetector assumes no prior knowledge (e.g., fingerprints) of the environment and uses only on-board sensors common to mainstream mobile phones. Being a generic and lightweight service component, IODetector greatly benefits many location-based and context-aware applications. We prototype the IODetector on Android mobile phones and evaluate the system comprehensively with data collected from 34 traces that include 133 different places during a 6-week period, employing different phone models. We further perform a case study where we make use of IODetector to instantly infer the GPS availability and localization accuracy in different indoor/outdoor environments.

Receiver autonomous integrity monitoring availability and fault detection capability comparison between BeiDou and GPS

This paper used the statistical methods of quality control to assess receiver autonomous integrity monitoring (RAIM) availability and fault detection (FD) capability of BeiDou14 (Phase II with 14 satellites), BeiDou (Phase III with 35 satellites) and GPS (with 31 satellites) for the first time. The three constellations are simulated and their RAIM performances are quantified by the global, Asia-Pacific region and temporal variations respectively. RAIM availability must be determined before RAIM detection. It is proposed that RAIM availability performances from satellites and constellation geometry configuration are evaluated by the number of visible satellites (NVS, NVS > 5) and geometric dilution of precision (GDOP, GDOP < 6) together. The minimal detectable bias (MDB) and minimal detectable effect (MDE) are considered as a measure of the minimum FD capability of RAIM in the measurement level and navigation position level respectively. The analyses of simulation results testify that the average global RAIM performances for BeiDou are better than that for GPS except global RAIM holes proportion. Moreover, the Asia-Pacific RAIM performances for BeiDou are much better than that for GPS in all indexes. RAIM availability from constellation geometry configuration and RAIM minimum FD capability for BeiDou14 are better than that for GPS in Asia-Pacific region in all cases, but the BeiDou14 RAIM availability from satellites are worse than GPS’s. The methods and conclusions can be used for RAIM prediction and real-time assessment of all kinds of Global Navigation Satellite Systems (GNSS) constellation.

GNSS RAIM Performance Analysis for World Wide Area

Multi-constellations provide much better satellite geometrics, thus RAIM algorithms areexpected to achieve greater reliability and integrity performance. This paper mainly discusses different RAIM algorithms and gives simulations of RAIM availability and reliability of standalone GPS and integrated GPS/GLONASS, GPS/BEIDOU and GPS/GLONASS/BEIDOU constellations.The results show that multi-constellation improve RAIM availability and reliability greatly. It is no less than 99.7%for APV I. Also MDB values indicate thatinternal and external reliability of satellite navigation system can be enhanced by multi-constellation.

SBAS operation in the Indian sector under simultaneous scintillation on different GNSS links

Scintillation observations of transionospheric signals from two GEOs (55°E and 140°E) and from the satellite constellations of GPS and GLONASS are carried out simultaneously during the equinoctial months of high solar activity years (2011–2012) from Raja Peary Mohan College (RPMC) center situated near the equatorial ionization anomaly (EIA) crest to study the vulnerability conditions of SBAS operation. Scintillations in excess of ~10dB are recorded simultaneously in the two GEO links in ~8% of the observing days with an average duration of ~28min. Under this condition the availability of GPS and GLONASS also falls below the optimum number (4) necessary for navigation solution, rendering the SBAS operation doubtful. GPS is found to be more susceptible to exhibit receivers׳ loss of lock than the GLONASS. The study reveals that two GEO links with pierce point longitude separation of ~10° are not suitable for maintaining faithful SBAS opeartion around the EIA crest. Occurrence of GEO scintillations is found to be associated with the strength and duration of the emerging post-sunset EIA structure.

Bluetooth aided mobile phone localization

It is meaningful to design a strategy to roughly localize mobile phones without a GPS by exploiting existing conditions and devices especially in environments without GPS availability (e.g., tunnels, subway stations, etc.). The availability of Bluetooth devices for most phones and the existence of a number of GPS equipped phones in a crowd of phone users enable us to design a Bluetooth aided mobile phone localization strategy. With the position of GPS equipped phones as beacons, and with the Bluetooth connection between neighbor phones as proximity constraints, we formulate the problem into an inequality problem defined on the Bluetooth network. A recurrent neural network is developed to solve the problem distributively in real time. The convergence of the neural network and the solution feasibility to the defined problem are both theoretically proven. The hardware implementation architecture of the proposed neural network is also given in this article. As applications, rough localizations of drivers in a tunnel and localization of customers in a supermarket are explored and simulated. Simulations demonstrate the effectiveness of the proposed method.

Coordinate estimation accuracy of static precise point positioning using on-line PPP service, a case study

Precise Point Positioning (PPP) is a combination of the original absolute positioning concept and differential positioning techniques. In PPP we use observation data from a single receiver and additional information of GNSS biases and errors derived from permanent networks. Since PPP was developed based only on GPS observations, the accuracy, availability and reliability of positioning is quite dependent on the number of visible satellites. One possible way to increase the availability of satellites is to integrate GPS and GLONASS observations. Nowadays such integration in PPP is available.

Performance Analysis of Micro blaze Implemented GPS-INS Integrated Systems on Spartan 6 and Zynq FPGAs

This paper compares the performances of two loosely coupled Micro blaze Implemented GPS-INS Integrated Systems On Spartan 6 And Zynq FPGAs. The first system usesa Micro blaze implemented GPS-INS integrated system on Spartan 6 Field Programmable Gate Array (FPGA) for inertial navigation solution and Kalman filter computation.The second system uses a Micro blaze implemented GPS-INS integrated system on Zynq FPGA for inertial navigation solution and Kalman filter computation . Real time issues related to accuracy of position, GPS outages, Selective availability of GPS, Higher variances of accelerometers, Resource usage of FPGA in terms of Slices, DSP48 and Block Random Access Memory (BRAM), Computation time, latency, and power consumption are presented.The systems are designed to give real time processed navigation solutions with an update rate of 100 Hz.

Terrestrial photogrammetry without ground control points

Terrestrial photogrammetry should be the survey technique of choice when updating large scale urban maps and GIS databases, where 3D data and attribute data are required. Its main drawback is the need for Ground Control Points (GCP) to reference the survey. To make image georeferencing easier and to provide control information, the use of a simple system, made of a photogrammetric camera fastened to a GPS antenna, is proposed. A photogrammetric block, composed by at least three images, is taken around the object with the receiver measuring in kinematic mode. Tie points are automatically extracted by Structure from Motion (SfM) algorithms or measured manually; block orientation is performed by GPS assisted Aerial Triangulation. Advantages as well as limitations of the system are discussed, with particular attention to GPS availability or ill-conditioned block configurations. The issue of system calibration (i.e. measurement of eccentricity between camera and antenna) is also addressed. Several test cases are presented, in which absolute accuracies, verified on check points independently surveyed range from 4 to 7 cm.

Path Planning for Mobile Mapping System Considering the Geometry of the GPS Satellite

In this paper, we propose a path planning method for a Mobile Mapping System (MMS) considering GPS geometry for the purpose of increasing GPS availability. We calculate Position Dilution of Precision (PDOP) using aerial laser survey data that provides geography and height of buildings near roads. PDOP is used for weighting road network data. By using the Chinese postman problem, we then calculate the optimum path that passes through all routes at least once. We describe currentMMS operation first and clear up problems with the current method. We then describe the proposed method in detail. Finally, we conduct evaluation tests and describe results in detail. The evaluation test verifies that the proposed method increases the GPS FIX ratio by 5% under the same GPS geometry and proves the effectiveness of the proposed method.

Path Planning for Autonomous Vehicles Using QZSS and Satellite Visibility Map

This paper describes a path planning method that uses the Quasi-Zenith Satellites System(QZSS) and a satellite visibility map for autonomous vehicles. QZSS is a positioning system operated by Japan that has an effect similar to an increase in the number of GPS satellites. Therefore, QZSS can be used to improve the availability of GPS positioning. A satellite visibility map is a special map that simulates the number of visible satellites at all points on the map. The vehicle can use the satellite visibility map to determine the points that receive more satellite signals. The proposed method generates the artificial potential fields from the satellite visibility map and obstacle information around the vehicle, and it generates the path following the potential fields. Thereby, the vehicle can select the path that has more satellite signals, improving the availability of GPS fixed solutions. Hence, the vehicle can reduce the accumulated error by dead reckoning, and it can improve the safety of self-control. In this study, we evaluate the satellite visibility maps and the path planning method. The results show that the proposed method does improve the availability of GPS fixed solutions.

Posterior representation with a multi‐modal likelihood using the gaussian sum filter for localization in a known map

AbstractA Gaussian sum filter (GSF) with component extended Kalman filters (EKF) is proposed as an approach to localizing an autonomous vehicle in an urban environment with limited GPS availability. The GSF uses vehicle‐relative vision‐based measurements of known map features coupled with inertial navigation solutions to accomplish localization in the absence of GPS. The vision‐based measurements have multimodal measurement likelihood functions that are well represented as weighted sums of Gaussian densities. The GSF is used because of its ability to represent the posterior distribution of the vehicle pose with better efficiency (fewer terms, less computational complexity) than a corresponding bootstrap particle filter with various numbers of particles because of the interaction with measurement hypothesis tests. The expectation‐maximization algorithm is used off line to determine the representational efficiency of the particle filter in terms of an effective number of Gaussian densities. In comparison, the GSF, which uses an iterative condensation procedure after each iteration of the filter to maintain real‐time capabilities, is shown through a series of in‐depth empirical studies to more accurately maintain a representation of the posterior distribution than the particle filter using 37 min of recorded data from Cornell University's autonomous vehicle driven in an urban environment, including a 32 min GPS blackout. © 2012 Wiley Periodicals, Inc.

Parametric Study on Wide Area Augmentation System for GPS Accuracy Enhancment

GPS systems are used extensively for location determination in outdoor and urban areas. Many location-based services based on GPS system were introduced to the market over the previous few years. The GPS system was found to be of considerable limited accuracy due to several reasons which cause the accuracy to be in a range of 4 meters. Due to this, several accuracy enhancement techniques were proposed and some of them were standardized and deployed. The Wide Area Augmentation System (WAAS) is one these techniques which was developed in order to improve the GPS signal accuracy, availability and integrity. This paper focuses on the WAAS parameters and their performance in different environmental conditions that could cause ionospheric, satellite clock, and ephermis errors which consequently degrade the accuracy of the GPS signal. The WAAS architecture, performance, and main parameters are presented and their performance is simulated and analyzed under storming conditions. In addition, the potential of using the WAAS in combination with augmentation systems is discussed.

Mobile Visual Location Recognition

With recent advances in CBIR, mobile visual location recognition becomes feasible. Using video recordings of a mobile device as a visual fingerprint of the environment and matching them to a georeferenced database provides pose information in a very natural way. Hence, LBSs can be provided without complex infrastructure in areas where the accuracy and availability of GPS is limited. This includes indoor environments where georeferenced data are just about to become publicly available.

MoveMine

With the maturity and wide availability of GPS, wireless, telecommunication, and Web technologies, massive amounts of object movement data have been collected from various moving object targets, such as animals, mobile devices, vehicles, and climate radars. Analyzing such data has deep implications in many applications, such as, ecological study, traffic control, mobile communication management, and climatological forecast. In this article, we focus our study on animal movement data analysis and examine advanced data mining methods for discovery of various animal movement patterns. In particular, we introduce a moving object data mining system, MoveMine, which integrates multiple data mining functions, including sophisticated pattern mining and trajectory analysis. In this system, two interesting moving object pattern mining functions are newly developed: (1) periodic behavior mining and (2) swarm pattern mining . For mining periodic behaviors, a reference location-based method is developed, which first detects the reference locations, discovers the periods in complex movements, and then finds periodic patterns by hierarchical clustering. For mining swarm patterns, an efficient method is developed to uncover flexible moving object clusters by relaxing the popularly-enforced collective movement constraints. In the MoveMine system, a set of commonly used moving object mining functions are built and a user-friendly interface is provided to facilitate interactive exploration of moving object data mining and flexible tuning of the mining constraints and parameters. MoveMine has been tested on multiple kinds of real datasets, especially for MoveBank applications and other moving object data analysis. The system will benefit scientists and other users to carry out versatile analysis tasks to analyze object movement regularities and anomalies. Moreover, it will benefit researchers to realize the importance and limitations of current techniques and promote future studies on moving object data mining. As expected, a mastery of animal movement patterns and trends will improve our understanding of the interactions between and the changes of the animal world and the ecosystem and therefore help ensure the sustainability of our ecosystem.

Extending GPS carrier phase availability indoors with a deeply integrated receiver architecture

GPS availability and continuity are challenged indoors and cannot be ensured when a traditional receiver fails to track enough GPS satellites for a complete navigation solution: i.e., when less than four satellites can be tracked. The sensor diversity approach described in this article was designed to support precise navigation and timing capabilities in any environment and at any time, but GPS is still a critical part of sensor diversity even in challenging signal conditions. This article describes an advanced GPS signal processing architecture and illustrates how it can be applied to extend the GPS coverage into difficult environments such as indoors, urban canyons, and under dense foliage canopies. The article also reports the results of a feasibility study that evaluates the cm-level carrier phase availability and signal quality using real deeply integrated receiver hardware using live GPS data collected indoors without the need for external network assistance. This article focuses primarily on the carrier phase measurement as it is the most useful for inertial calibration. The test results presented herein indicate that deep integration enables reliable GPS measurements for many dynamic indoor scenarios.

Gaussian process regression approach for bridging GPS outages in integrated navigation systems

A Kalman filter (KF) enhanced by the Gaussian process regression (GPR) technique is suggested to bridge GPS-outages in navigation solutions where inertial navigation systems (INS) and GPS are integrated. A KF utilises linearised dynamic models. If a low-cost MEMS-based INS with complex stochastic nonlinearity is considered, performance degrades significantly during short periods of GPS-outages owing to linearised models. Proposed is a novel usage of GPR as a nonlinear INS-errors predictor. During GPS availability, the correct vehicle state, sensor measurements, and INS output deviations from GPS are collected. During GPS-outages, GPR is applied to this data set to predict INS deviations enabling the KF to estimate all INS errors. The proposed technique was tested on real road experiments showing significant improvements during long GPS-outages.

Modelling and prediction of GPS availability with digital photogrammetry and LiDAR

This paper describes an automated method for predicting the number of satellites visible to a GPS receiver, at any point on the Earth's surface at any time. Intervisibility analysis between a GPS receiver and each potentially visible GPS satellite is performed using a number of different surface models and satellite orbit calculations. The developed software can work with various ephemeris data, and will compute satellite visibility in real time. Real‐time satellite availability prediction is very useful for mobile applications such as in‐car navigation systems, personal navigations systems and LBS. The implementation of the method is described and the results are reported.

Precise Robust Positioning with Inertially Aided RTK

: This paper addresses the problem of “robust” positioning, which is the ability of a positioning system to determine position with continuous accuracy in spite of GPS outages. The paper describes an aided INS (AINS) with inertially aided RTK (IARTK) as one solution to a robust RTK positioning problem. It describes the design of the IARTK-AINS and discusses the factors that control the maximum outage duration for rapid fixed integer ambiguity recovery and the position accuracy during the outage. The IARTK-AINS implements tightly coupled inertial/GPS integration with floated ambiguity estimation and fixed integer search in a single Kalman filter. The IARTK-AINS is able to recover L1 integer ambiguities within seconds of a short-duration GPS outage while maintaining decimeter-level accuracy throughout the outage. The paper then describes the performance of the IARTK-AINS during various tests involving controlled GPS outages and uncontrolled GPS availability during navigation in a demanding urban canyon environment.

Positioning accuracy and reliability of GALILEO, integrated GPS-GALILEO system based on single positioning model

A kind of uniform reliability index suitable for the code and phase observations is presented and used in reliability evaluation of satellite systems. Then, based on 25 stations of Crustal Movement Observation Network of China, satellite visibility, positioning availability and observation reliability of GPS, GALILEO and integrated GPS-GALILEO are calculated and analyzed in detail. Simulation results reveal that the satellite visibility of GALILEO is superior to that of GPS. Given positioning accuracy, horizontal positioning availability of GALILEO is consistent with that of GPS, but its vertical positioning availability is superior to that of GPS. However, the integrated GPS-GALILEO is shown to be superior to each of the single systems in the aspects of positioning accuracy and availability. The reliability of code and phase observations based on GALILEO and integrated GPS-GALILEO system is superior to that of GPS both in spatial and temporal domains on the whole. The new reliability index presented is simple to calculate and reflects reliability differences of different satellite systems.