This article presents a new tracking technique for sine-BOC(n, n) (or Manchester encoded) ranging signals, which will most likely be part of the new European Global Navigation Satellite System (GNSS), Galileo, signal plan. When traditional sine-BOC(n, n) tracking is considered, although offering excellent performance compared with current signals, it has the main drawback of potentially giving biased measurements. The new method presented herein allows the removal of this threat while maintaining the same level of performance. An adapted version of this technique can also be used for acquisition purposes.
The use of Global Navigation Satellite System (GNSS) for positioning has grown significantly in recent years thanks in particular to the development of several mass-market applications, such as car navigation or mobile positioning. Unfortunately, in difficult environments such as dense urban or indoor areas, GNSS exhibits degraded performances in terms of precision and availability. The use of signals of opportunity is one of the solutions to replace or assist GNSS in those environments. These signals are communication signals that are usually designed to provide a service in dense environment and can thus be used in location where GNSS is unavailable. Several commercial positioning services based on signals of opportunity already exist such as ROSUM with ATSC digital TV signals, or Skyhook with Wi-Fi signals This paper investigates the potential of the digital TV European (but used worldwide) standard DVB-T, based on an OFDM air interface, to supply a navigation service. To support a previously proposed DVB-T receiver architecture, a DVB-T receiver simulator is presented that includes the principal blocks required for communication with enhanced navigation-oriented functionalities. In particular, this simulator includes a Delay Lock Loop (DLL) for accurate synchronization purpose. The theoretical expressions of pseudo-range sigma error and tracking threshold in case of Line-Of-Sight (LOS) signal are proposed and compared to simulation results, in order to validate the DLL module of the simulator. Then, performances in a more realistic Rayleigh multipath channel are presented. This paper also proposes description and explanations of impairments due to absence of LOS signal in urban environment and points out the limits of existing urban channel propagation models for a positioning solution.
Positioning in urban or indoor environments is a hot topic, due to both regulations such as the E911 and extension of location-based services targeting the mass market concentrated in metropolitan areas. In deep urban or indoor areas, it is generally recognized that satellite-based positioning systems are not suitable (alone) to provide a continuous, reliable, and accurate position to the user. Therefore, alternative positioning techniques may be useful to complement or replace satellite positioning in these environments. This paper investigates the possibility of using a mobile TV system based on the DVB-SH standard as a system of opportunity for positioning. A system-level modification is used in order to make emitter discrimination possible in the synchronized emitter network. Then, the signal processing steps required for pseudorange estimation are detailed. The proposed method is simulated using realistic channel sounding measurements and provides a mean positioning error around 40 m.
Various Road User Charging (RUC) mechanisms are used to control the traffic and its resulting pollution, as well as revenue sources for reinvestment in the road infrastructure. Among them, Electronic Toll Collection (ETC) systems based on user positions estimated with Global Navigation Satellite Systems (GNSS) are particularly attractive due to their flexibility and reduced roadside infrastructure in comparison to other systems like tollbooths. Because GNSS positioning may be perturbed by different errors and failures, ETC systems, as liability critical applications, should monitor the integrity of GNSS signals in order to limit the use of faulty positions and the consequent charging errors. The integrity monitoring systems have been originally designed for civil aviation, so they need to be adapted to the ETC requirements. This paper studies the use of Receiver Autonomous Integrity Monitoring (RAIM), which are algorithms run within the GNSS receiver, and therefore easier to tune to ETC needs than other systems based on external information. The Weighted Least Squares Residuals (WLSR) RAIM used in civil aviation is analyzed, and an algorithm modification for ETC is proposed. Simulations demonstrate that the proposed RAIM algorithm has a superior level of availability over civil aviation based RAIM procedures, particularly in urban environments.
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