Publications
339 results found
Bhatti UI, Ochieng WY, Feng S, 2012, Performance of rate detector algorithms for an integrated GPS/INS system in the presence of slowly growing error, GPS SOLUTIONS, Vol: 16, Pages: 293-301, ISSN: 1080-5370
- Author Web Link
- Cite
- Citations: 28
Nascimento FAC, Majumdar A, Ochieng WY, et al., 2012, A multistage multinational triangulation approach to hazard identification in nighttime offshore helicopter operations, Reliability Engineering & System Safety, Vol: 108, Pages: 142-153, ISSN: 0951-8320
Jokinen A, Feng S, Ochieng W, et al., 2012, Fixed ambiguity Precise Point Positioning (PPP) with FDE RAIM, Position Location and Navigation Symposium (PLANS), 2012 IEEE/ION
Schuster W, Porretta M, 2012, High-accuracy four-dimensional trajectory prediction for civil aircraft, Aeronautical Journal, Vol: 116, Pages: 45-66, ISSN: 0001-9240
Feng S, Ochieng W, Samson J, et al., 2012, Integrity Monitoring for Carrier Phase Ambiguities, JOURNAL OF NAVIGATION, Vol: 65, Pages: 41-58, ISSN: 0373-4633
- Author Web Link
- Cite
- Citations: 26
Schuster W, Ochieng W, 2012, Uncertainties in future trajectory predictors – sensitivity analysis (in preparation), Aeronautical Journal
Jokinen A, Feng S, Schuster W, et al., 2012, High integrity GPS/GLONASS Precise Point Positioning (PPP) with GPS ambiguity resolution (in preparation)
Juan JM, Hernandez-Pajares M, Sanz J, et al., 2012, Enhanced Precise Point Positioining for GNSS Users, IEEE Transaction on Geoscience and Remote Sensing, Pages: 1-11
Wilke S, Majumdar A, Ochieng W, 2012, A framework for assessing the quality of aviation safety databases, Submitted for review
Wilke S, Majumdar A, Ochieng W, 2012, Airport surface operations: A holistic framework for operations modeling and risk management, Submitted for review
Wilke S, Majumdar A, Ochieng W, 2012, Holistic approach towards airport surface safety, Transportation Research Record - Aviation, Vol: 2300, Pages: 1-12
Kyriakidis M, Majumdar A, Gudela G, et al., 2012, The development and assessment of a performance shaping factors taxonomy for railway operations, Transportation Research Record: Journal of the Transportation Research Board, Vol: 2289, Pages: 145-153
Schuster W, Ochieng W, 2012, Gate-to-gate advanced trajectory predictor for future Air Traffic Management under SESAR, NextGen and beyond (in preparation), Journal of Navigation
Schuster W, Bai J, Feng S, et al., 2012, Integrity monitoring algorithms for airport surface movement, GPS Solutions, Vol: 16, Pages: 65-75
Nur K, Feng S, Ling C, et al., 2012, Application of the Improved FOCUSS for Arrival Time Estimation (IFATE) Algorithm to WLAN High Accuracy Positioning Services, 2012 UBIQUITOUS POSITIONING, INDOOR NAVIGATION, AND LOCATION BASED SERVICE (UPINLBS)
Molloy J, Melo PC, Graham DJ, et al., 2012, The Role of Air Travel Demand Elasticities in Reducing Aviation's CO2 Emissions: Evidence for European Airlines, Transportation Research Record: Journal of the Transportation Research Board
Kyriakidis M, Majumdar A, Ochieng WY, 2012, A human performance operational railway index to estimate operator's error probability, Advances in Human Aspects of Road and Rail Transportation, Publisher: CRC Press, Pages: 832-841, ISBN: 9781439871232
Jiang Z, Groves PD, Ochieng WY, et al., 2011, Multi-constellation GNSS multipath mitigation using consistency checking, Pages: 3889-3902
In a typical urban environment, a mixture of multipath-free, multipath-contaminated and non-line-of-sight (NLOS) propagated GNSS signals are received. The errors caused by multipath-contaminated and NLOS reception are the dominant source of reduced consumer-grade positioning accuracy in the urban environment. Many conventional receiver-based and antenna-based techniques have been developed to mitigate either multipath or NLOS reception with mixed success. Nevertheless, the positioning accuracy can be maximised based on the simple principle of selecting only those signals least contaminated by multipath and NLOS propagation to form the navigation solution. The advent of multi-constellation GNSS provides the opportunity to realise this technique that is potentially low-cost and effective for consumer-grade devices. It may also be implemented as an augmentation to other multipath mitigation techniques. The focus of this paper is signal selection by consistency checking, whereby measurements from different satellites are compared with each other to identify the NLOS and most multipath-contaminated signals. The principle of consistency checking is that multipath-contaminated and NLOS measurements produce a less consistent navigation solution than multipath-free measurements. RAIM-based fault detection operates on the same principle. Three consistency-checking schemes based on single-epoch least-squares residuals are assessed: single sweep, recursive checking and a hybrid version of the first two. Two types of weighting schemes are also considered: satellite elevation-based and signal C/N 0-based weighting. The paper also discussed the different observables that may be used by a consistency-checking algorithm for different applications and their effect on detection sensitivity. Test results for the proposed algorithms are presented using data from both static positioning and stand-alone dynamic positioning experiments. The static data was collected using a pair of survey-
Milner C, Feng S, Jokinen A, et al., 2011, A holistic approach to Carrier-Phase Receiver Autonomous Integrity Monitoring (CRAIM), Pages: 2689-2695
Pseudorange-based integrity monitoring such as Receiver Autonomous Integrity Monitoring (P-RAIM) and its variations, has been studied extensively over recent decades. This has primarily been driven by the safety critical nature of aviation and the important link to the integrity of the positioning and navigation solution required. However, for higher accuracy applications, the more precise carrier phase measurements are used. The applications include positioning both in static and dynamic modes, with the latter employing Real Time Kinematic (RTK) positioning techniques. Furthermore, for mission critical applications such as airport surface movement in which safety is critical, user receiver level integrity monitoring akin to P-RAIM for carrier phase data is required. The state-of-the-art in user receiver level integrity monitoring with carrier phase measurements is formed of two distinct steps; ambiguity validation and a traditional RAIM consistency checking step which assumes fixed ambiguities. This paper proposes a holistic Carrier phase RAIM (C-RAIM) technique that integrates the two processes. The key to accurate and reliable carrier-phase positioning is reliable determination of integer phase ambiguities. A number of methods are currently used, the most popular being the Least-squares AMBiguity Decorrelation Adjustment or LAMBDA, as well as the simpler but sub-optimal integer rounding and sequential integer rounding or bootstrapping. This is followed by a process to confirm the quality of the resulting ambiguities, referred to as ambiguity validation. The main approach to ambiguity validation uses statistical tests such as the ratio test, F-test, W-ratio and χ 2-test which are not justified in theory. However, recent studies have looked to characterise the distribution of the test statistic or incorrect ambiguity vector more accurately in order to provide an estimate of confidence in the ambiguity resolution step. These include; the Integer Aperture (IA) me
Feng S, Milner C, Jokinen A, et al., 2011, A novel positioning and integrity monitoring algorithm for a multiple constellation receiver, Pages: 2681-2688
With an increasing number of navigation satellites, full operation of multiple constellations is on the horizon. This will bring both opportunities and challenges for user level positioning and integrity monitoring. The opportunities will be facilitated by amongst others, more satellites, frequencies, message types, and better signal design and geometry. The challenges are not only to deal with the differences among satellite navigation systems but also to maximize the benefit from the similarity of multiple constellation signals to develop, for example, low cost, high performance receivers for mass market applications. The current methods for positioning using multiple constellations focus on dealing with differences especially those associated with the time reference. This is dealt with either by the use of information broadcast by the systems or treatment as an unknown to be estimated as part of the solution. This paper proposes a novel positioning and integrity monitoring algorithm for multiple constellation receivers. The positioning method is based on single differences of pairs of measurements from two constellations, for example, the difference between the measurements from a GPS satellite and one or more Galileo satellites. The single difference removes the real receiver clock bias and drift error. Therefore, the inter-system time difference appears as common bias, and is estimated as a virtual receiver clock error. In addition, a carefully selected pair can also mitigate correlated un-modeled errors, thus improving the quality of the positioning solution. One approach to forming the single difference (i.e. basic pairs) is to use satellites in different constellations that are in close proximity. The degree of closeness depends on the user location, time, configuration and status of constellations. For example, signals from the paired satellites with similar elevation and azimuth should help mitigate un-modeled and correlated errors. The corresponding integ
Milner C, Ochieng W, Schuster W, et al., 2011, A Regional Space Segment Health Monitor for Local GPS Integrity Monitoring, Journal of Navigation, Vol: 64, Pages: 657-671, ISSN: 0373-4633
Nascimento FAC, Majumdar A, Jarvis S, et al., 2011, Safety hazards in nighttime offshore helicopter operations, 37th European Rotorcraft Forum 2011
Schuster W, Ochieng W, 2011, Airport Surface Movement - Critical Analysis of Navigation System Performance Requirements, JOURNAL OF NAVIGATION, Vol: 64, Pages: 281-294, ISSN: 0373-4633
- Author Web Link
- Cite
- Citations: 5
Milner CD, Ochieng WY, 2011, Weighted RAIM for APV : The <i>Ideal</i> Protection Level, JOURNAL OF NAVIGATION, Vol: 64, Pages: 61-73, ISSN: 0373-4633
- Author Web Link
- Cite
- Citations: 23
Schuster W, Ochieng W, Majumdar A, 2011, Trajectory prediction and conflict resolution for Enroute-to-enroute Seamless Air traffic management – TESA, SESAR Innovation Days
Schuster W, Ochieng W, 2011, Novel Integrity Concept for CAT III Precision Approaches and Taxiing: Extended GBAS (E-GBAS), Journal of Navigation, Vol: 4
Schuster W, Ochieng W, 2011, Novel Integrity Concept for CAT III Precision Approaches and Taxiing: Extended GBAS (E-GBAS), Journal of Navigation, Vol: 64, Pages: 695-710
Schuster W, Ochieng W, 2011, Airport Surface Movement – Critical Analysis of Navigation System Performance Requirements, Journal of Navigation, Pages: 281-294
Milner C, Ochieng W, 2010, ARAIM for LPV-200: The ideal protection level, Pages: 3191-3198
Receiver Autonomous Integrity Monitoring (RAIM) has been used successfully for horizontal phases of flight up to Non-Precision Approach. However, the use of single frequency measurements from the current GPS constellation is unable to meet the stringent requirements for vertical guidance. In the coming years, the expected availability of protected multiple frequency signals for civil mission critical applications and increase in the number of satellites available as a result of modernized and new systems (GALILEO, GLONASS, Compass), have raised the possibility of using RAIM for more demanding phases of flight. LPV-200 operations are currently the focus of this endeavor within the U.S under the GNSS Evolutionary Architecture Study and within Europe. Three architectures have been identified as having the potential to meet LPV-200 on a global scale, a GNSS Integrity Channel, Relative RAIM and Absolute RAIM (ARAIM). This paper focuses on using the concept of an ideal Protection Level (PL) developed by the authors of this abstract (Milner and Ochieng, 2009) within the ARAIM framework (Blanch et al, 2007; Lee and McLaughlin, 2007). The ideal PL has been developed as previous protection levels employed within slope based RAIM have either been overly conservative in their approximation or fail to ensure sufficient integrity in all cases. The ideal PL uses a two step iterative search for the protection level and worst case bias which match the integrity risk requirement exactly. The approach is rigorous but includes a number of checks to accelerate the processing and provide sufficient efficiency to be a plausible solution both in an offline and real-time implementation. Previous processing algorithms for the ideal PL have focused on slope based RAIM which uses a chi-squared test statistic for a single failure hypothesis. The proposed algorithms for ARAlM are based on the historical Solution Separation method applied to a Multiple Hypothesis formulation (MHSS). The recent de
Flament D, Brocard D, Ochieng W, et al., 2010, RAIM in dual frequency / multi constellation APV/LPV operations in aeronautics
In aeronautics, Receiver Autonomous Integrity Monitoring (RAIM) techniques based on GPS L1 measurements are currently used in En-route and NPA operations, but not in those that require vertical guidance (APV operations/LPV procedures like LPV200). For these phases of flight SBAS, GBAS or classical ILS navaids are used because they offer better performance than GPS RAIM. However, in future RAIM performance is expected to improve significantly due to the deployment of new GNSS constellations in addition to GPS and a second frequency (L5) protected for use in aviation. The former will result in more satellites being available to the user and the latter will enable ionosphere delays to be corrected for autonomously onboard. Therefore, it is envisaged that RAIM will play a significant role in APV operations in the future. This paper highlights the possible role for multi constellation RAIM techniques in APV operations and identifies their advantages and limitations. The candidate algorithms are then reviewed in detail and conclusions drawn on their potential and future research. ©2010 IEEE.
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.