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Des techniques fiables de radiolocalisation s’avèrent indispensables au développement d’un grand nombre de nouveaux systèmes pertinents. Les techniques de localisation basées sur les réseaux de communication sans-fil (WNs) sont particulièrement adéquates aux espaces confinés et fortement urbanisés. Le présent projet de recherche s’intéresse aux systèmes de localisation en temps réel (RTLS) basés sur les technologies de communication sans-fil existantes. Deux nouvelles techniques de radiolocalisation alternatives sont proposées pour améliorer la précision de positionnement des nœuds sans-fil mobiles par rapport aux méthodes conventionnelles basées sur la puissance des signaux reçus (RSS). La première méthode de type géométrique propose une nouvelle métrique de compensation entre les puissances de signaux reçus par rapport à des paires de stations réceptrices fixes. L’avantage de cette technique est de réduire l’effet des variations du milieu de propagation et des puissances d’émission des signaux sur la précision de localisation. La même métrique est sélectionnée pour former les signatures utilisées pour créer la carte radio de l’environnement de localisation durant la phase hors-ligne dans la deuxième méthode de type analyse de situation. Durant la phase de localisation en temps réel, la technique d’acquisition comprimée (CS) est appliquée pour retrouver les positions des nœuds mobiles à partir d’un nombre réduit d’échantillons de signaux reçus en les comparant à la carte radio préétablie. Le calcul d’algèbre multilinéaire proposé dans ce travail permet l’utilisation de ce type de métrique ternaire, équivalemment la différence des temps d’arrivée (TDOA), pour calculer les positions des cibles selon la technique de CS. Les deux méthodes sont ensuite validées par des simulations et des expérimentations effectuées dans des environnements à deux et à trois dimensions. Les expériences ont été menées dans un bâtiment multi-étages (MFB) en utilisant l’infrastructure sans-fil existante pour retrouver conjointement la position et l’étage des cibles en utilisant les techniques proposées. Un exemple emblématique de l’application des RTLS dans les zones urbaines est celui des systèmes de transport intelligents (ITS) pour améliorer la sécurité routière. Ce projet s’intéresse également à la performance d’une application de sécurité des piétons au niveau des intersections routières. L’accomplissement d’un tel système repose sur l’échange fiable, sous des contraintes temporelles sévères, des données de positionnement géographique entre nœuds mobiles pour se tenir mutuellement informés de leurs présences et positions afin de prévenir les risques de collision. Ce projet mène une étude comparative entre deux architectures d’un système ITS permettant la communication entre piétons et véhicules, directement et via une unité de l’infrastructure, conformément aux standards de communication dans les réseaux ad hoc véhiculaires (VANETs).

This report describes an assessment of using dedicated short-range communications(DSRC) technology to perform travel time monitoring and automated incident detectionon a segment of rural freeway. The assessment used the CORSIM traffic simulation toolto simulate traffic and incidents on a segment of rural freeway. Output data from thesimulation was subjected to post-processing to produce the "probe and beacon" data thatwould be produced by a DSRC-based system. An incident detection algorithm wasdeveloped, which used a travel time threshold and a counter. Travel times exceeding thethreshold incremented the counter, while travel times below the threshold decrementedthe counter (unless it was at zero). An alarm was generated when the counter reached apre-selected level. This algorithm was tested on selected data files, and the results wereused to identify the "best" values of the threshold and counter alarm level. Using these"best" values, the algorithm was then applied to the "probe and beacon" data todetermine how quickly the system could detect various traffic incidents. The analysisshowed that the system could provide rapid and reliable detection of incidents.During the simulation and analysis, several parameters were varied to observe theirimpacts on the system performance. These parameters included traffic volume, incidentseverity, percentage of vehicles with transponders, spacing of roadside readers, andlocation of the incident relative to the next downstream reader. Each parameter proved tohave a significant effect on the detection time, and the observed impacts were consistentwith logical expectations. In general, the time to detect an incident was reduced inresponse to (1) an increase in traffic volume, (2) an increase in incident severity, (3) anincrease in transponder population, (4) a reduction in reader spacing, and (5) a reductionin distance from incident location to next downstream reader.Preliminary estimates were developed of the costs associated with implementing aDSRC-based traffic monitoring system. The relationship between system cost andsystem performance was explored and illustrated.Recommendations were developed and presented. These included further analysis basedon traffic simulations, followed by a limited field deployment to validate the analysisresults.

In this effort, we consider the performance of a dedicated short range communication (DSRC) system for inter-vehicle communications (IVC). The DSRC standard employs convolutional codes for forward error correction (FEC). The performance of the DSRC system is evaluated in three different channels with convolutional codes, regular low density parity check (LDPC) codes and quasi-cyclic (QC) LDPC codes. In addition, we compare the complexity of these codes. It is shown that LDPC and QC-LDPC codes provide a significant improvement in performance compared to convolutional codes. / Graduate

© 2016 IEEE. This demo paper describes the architecture and communication protocols - both single hop and multi-hop - for DSRC devices. The paper also describes an Android application that enables visualization of real-time vehicle movements on Google map using DSRC and Bluetooth communication. The application receives information about position, speed and direction of mobility that multiple vehicles obtain through the GPS Receiver attached to their DSRC OBU. The android application communicates with one of the DSRC units through Bluetooth to gather real-time traces collected from all DSRC-equipped vehicles. The application displays live movement of these vehicles on Google map with their path history, speed and direction. The source code and installation files of this application will be released through the Open Source Application Development Portal (OSADP) hosted by the U.S. Department of Transportation.

Vehicle to Vehicle (V2V) communication provides a flexible and real-time information dissemination mechanism through various applications of Intelligent Transportation Systems (ITS). Achieving seamless connectivity through multi-hop vehicular communication with sparse network is a challenging issue. In this paper, we have studied this multi-hop vehicular connectivity in an urban scenario using GPS traces obtained from San Francisco Yellow cabs. Our current work describes a new algorithm for the analysis of topological properties like connectivity and partitions for any kind of vehicular or mobile computing environment. The novel approach uses bitwise manipulation of sparse matrix with an efficient storage technique for determining multi-hop connectivity. The computation mechanism can be further scaled to parallel processing environment. The main contribution of this research is threefold. First, developing an efficient algorithm to quantify multi-hop connectivity with the aid of bitwise manipulation of sparse matrix. Second, investigating the time varying nature of multi-hop vehicular connectivity and dynamic network partitioning of the topology. Third, deriving a mathematical model for calculating message propagation rate in an urban environment.

This paper presents an innovative system for taxi hailing service using V2X communication platform. This proposed system does not require any established operational center or explicit prior booking request through central operator like existing automated taxi dispatching systems. Rather, it provides distributed, self-organized and real time service of hailing a taxi cab in urban area. Our proposed application can be implemented using the state of the art DSRC communication platform in both V2V and V2I mode. In this paper, we introduce our designs of the system and the protocols, and present preliminary evaluation results that reveals numerous benefits of implementing this system. Based on the primary results obtained from real world GPS traces, it can be predicted that, our proposed system can significantly increase the availability of taxi cabs while reducing the wait time for the passenger. At the same time, from the perspective of a taxi driver, it can reduce the empty cruising time and increase daily trip count and eventually help increase the revenue of the taxi company.

Doppler effects on vehicular communication have been theoretically modeled by many researchers. However, very limited experimental studies have been conducted to investigate the impact of Doppler shift on the vehicle-to-vehicle (V2V) communication range and reliability with high speed mobility. The current work-in-progress research aims to quantify the impact of Doppler effects on V2V communication reliability, range, and reachability using singlehop Dedicated Short Range communications (DSRC) between two opposite traffic. We conducted our experiments by mounting the after-market DSRC on-board units on the dashboard of two vehicles that cross each other from opposite directions with constant relative speeds on a real interstate freeway. Our preliminary results indicate that the communication time and range drop to approximately 70% and 40% after the two vehicles cross and start moving away from each other with the average relative speeds of 110 and 140 mph, respectively. Similarly, the packet delivery ratio is also drastically reduced after the vehicles start moving away from each other. Apparently, these results indicate that there might be a strong effect of Doppler phenomena on the transmission range, packet delivery rate and the duration of the communication.

Traditional satellite positioning systems have limited resolution and have proved inaccuratein areas such as urban canyons where signals are subject to bounce phenomena or indeed may be entirely unavailable. An alternative method of positioning is that of tri/multilateration, which uses known positions and distances from beacon points to locate a receiver. In this project, a software was developed which used DSRC Basic Safety Messages (containing locational information) in combination with Received Signal Strength metrics (translated to distance information) to carry out such positioning in static environments. Initial studies confirmed that a signal received on the Craton 2 hardware was subject to considerable signal strength spread approximating a Gaussian distribution. A software was developed to simulate BSMs, including a measure of perturbation, over TCP. Three different traffic scenarios were constructed. Furthermore, multilaterationsoftware was developed to receive the BSMs and calculate position using three separate algorithms. The performance of these algorithms in the three different traffic scenarios was then evaluated. Lastly, the multilateration software was further developed to allow for the capture and processing of real BSMs sent on the 5.9 GHzband. The multilateration software was capable of determining the location of the receiver to varying degrees of accuracy, depending on the geometrical distribution of surrounding vehicles and the algorithm used to multilaterate. The 3D Linear Least Squares method performed well in situations where beacons were well spaced in three dimensions. Other implemented multilateration algorithms, i.e., a 2D Linear Least Squares method and a 3D Gauss Newton method, performed better in typical traffic scenarios where vehicles tend to be coplanar.The software developed provides a useful starting point for further developmentof static, but also dynamic, multilateration algorithms.

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