For outdoor and global navigation satellite system (GNSS) challenged scenarios, collaborative positioning algorithms are proposed to fuse information from GNSS satellites and terrestrial wireless systems. This paper derives the Cramer-Rao lower bound (CRLB) and algorithms for the angle-of-arrival (AOA)-assisted GNSS collaborative positioning. Based on the CRLB model and collaborative positionin...

The coming decade will bring a proliferation of Global Navigation Satellite Systems (GNSS) that are likely to revolutionize society in the same way as the mobile phone has done. The promise of a broader multi-frequency, multi-signal GNSS “system of systems” has the potential of enabling a much wider range of demanding applications compared to the current GPS-only situation. In order to achieve ...

Global Navigation Satellite System (GNSS) Receiver Autonomous Integrity Monitoring (RAIM) is essential for safety-of-life and liability critical applications. This paper discusses two fundamentally different ways to assess the integrity risk of an operation with RAIM, based on a different amount of information available : the expected (or average) performance that is computed using the GNSS mod...

Todd E. Humphreys is a research assistant professor in the department of Aerospace Engineering and Engineering Mechanics at the University of Texas at Austin. He will join the faculty of the University of Texas at Austin as an assistant professor in the Fall of 2009. He received a B.S. and M.S. in Electrical and Computer Engineering from Utah State University and his Ph.D. in Aerospace Engineer...

The use of space-time processing methods in GNSS interference mitigation is of great interest due to their effectiveness in both narrowband and wideband interference suppression. Techniques to reduce the distortion and bias on the cross correlation function due to space-time filtering are also very important especially for high precision GNSS applications. In this paper, different types of spac...

propagation of radio waves through the troposphere is based on minimum travel time between transmitter and receiver. the troposphere layer affects the propagation of gnss signals and causes errors in point positioning due to (1) delay of the signal, and (2) change of the curvature of the signal path. for this reason gnss users apply models for tropospheric error corrections. one of the commonly...

Benefits from the modernized US Global Positioning System (GPS), the revitalized Russian GLObal NAvigation Satellite System (GLONASS), and the newly-developed Chinese BeiDou Navigation Satellite System (BDS) and European Galileo, multi-constellation Global Navigation Satellite System (GNSS) has emerged as a powerful tool not only in positioning, navigation, and timing (PNT), but also in remote ...

Positioning, navigation, and timing (PNT) is a strategic key technology widely used in military and civilian applications. Global navigation satellite systems (GNSS) are the most important PNT techniques. However, the vulnerability of GNSS threatens PNT service quality, and integrations with other information are necessary. A chip scale atomic clock (CSAC) provides high-precision frequency and ...

Within the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) there is a need for an assessment of the uncertainty in the integrated water vapour (IWV) in the atmosphere estimated from ground-based global navigation satellite system (GNSS) observations. All relevant error sources in GNSS-derived IWV are therefore essential to be investigated. We present two approaches, a...

In contrast with ground applications the GNSS constellations are not optimized for space applications. Moreover, the different types of mission, i.e. Low Earth Orbit (LEO), Medium Earth Orbit (MEO), Geosynchronous Earth Orbit (GEO), have all specific requirements. Our motivation is to define an «Ubiquitous GNSS receiver (UGNSS)», i.e. a single receiver able to cope with all types of mission. Th...