Vehicular Ad-Hoc Network (VANET)s are a key element of Intelligent Transport System (ITS)s. One of the challenges in VANETs is dealing with awareness and congestion due to the high amount of messages received from the vehicles in communication range. As VANETs are used in critical applications, congestion on the receiver side caused by the buffering of the packets is a safety hazard. In this thesis, we propose a stream-wise queuing system on the receiver side and show how it improves the timeliness of the messages received and main- tains the awareness of the system in a congestion situation.

Vehicular ad hoc networks (VANETs) are instances of mobile ad hoc networks with the aim to enhance the safety and efficiency of road traffic. The basic idea is to allow arbitrary vehicles to broadcast ad hoc messages (e.g. traffic accidents) to other vehicles and remind drivers to change their route immediately or slow down to avoid dangers. However, some concerns of security and privacy are also raised in this environment. Messages should be signed and verified before they are trusted while the real identities of vehicles should not be revealed to guarantee the source privacy, but it still has to be traceable to prevent any abuse of VANETs (e.g. sending a fake message). Many related works have been presented in the literature so far. They can be generally divided into two constructions, where one is based on pseudonymous authentication and the other is based on group signatures. However, both of the two constructions have some drawbacks. Consequently, in this thesis, we come up with a provably secure and strong privacy preserving protocol based on the blind signature technique to guarantee privacy and fulfill other essential security requirements in the vehicular communication environment. Besides, compared with other similar works, we offer an efficient tracing mechanism to trace and revoke the vehicles abusing the VANETs. In addition, considering the real environment, we also provide simulation results to show that our scheme is more practical, efficient and suitable for VANETs under a real city street scenario with high vehicle density. Finally, we also demonstrate the security of the proposed protocol by formal proofs.

京都大学 / 新制・課程博士 / 博士(情報学) / 甲第23549号 / 情博第779号 / 新制||情||133(附属図書館) / 京都大学大学院情報学研究科通信情報システム専攻 / (主査)教授 原田 博司, 教授 大木 英司, 准教授 山本 高至 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DGAM

The aim of this work is to show the effectiveness of techniques that allow a user to maintain its privacy and anonymity while participating in real word scenario. Users need to communicate with each other in many situations in order to share information. This creates the danger of the user’s privacy being breached and it can discourage users from taking active participation in any information sharing task. There are many real scenarios or application where users want to remain anonymous while having their communication secured. This is so in vehicular communication systems. Group signatures are versatile cryptographic tools that are suitable when we need security and privacy protection. A group signature scheme allows members of a group to sign messages on behalf of the group. Any receiver can verify the message validity but cannot discover the identity of the sender from the signed message or link two or more messages from the same signer. However, the identity of the signer can be discovered by an authority using a signed message. For this reason, Group Signature schemes were proposed in the context of vehicular communication systems. In this context, communication and computation overheads are critical. Thus, the focus of this thesis is to implement and compare different group signature schemes in terms of overhead introduced due to processing cost, and analytically evaluate their suitability for vehicular communication scenarios.

This project has been carried out at the Electronic Embedded Systems Architecture Department at Volvo Construction Equipment (VCE), Eskilstuna, Sweden. It forms the baseline for a stepwise systematic research initiative to convert wired technologies used for certain in-vehicle control and communication components to wireless technologies. In-vehicle wireless networks are being increasingly improvised and researched to minimize the manufacturing and maintenance cost of the total amount of wiring harnesses within the vehicles. Fault tracking and maintenance becomes convenient within a wireless network. Wireless intra-vehicular communication provides an open architecture that can accommodate new components and applications. One such usability has been studied in this thesis for the Display Control Unit of Volvo paver machines. A newly designed hardware demands new technologies to ensure operator safety, security, comfort, convenience, and information. The research conducted in this thesis takes into account five probable use-cases in terms of control and communication around the new hardware, and studies suitable wireless technologies that could replace the wired technology that will be used. From a detailed literature study and the specifications provided by VCE, WAVE/IEEE802.11p and DMG/IEEE 802.11ad have been selected as optimal candidates. These two have been modelled at the physical layer of the system. After comparing the results of WAVE for 4 different channel models and 8 different coding and modulation schemes, it has been found that 1/2BPSK(3 Mbps) and 1/2 QPSK(6 Mbps) are optimal for the 3 Rician Fading Channels of Rural LOS, Urban LOS, and Highway LOS. For use-cases that involve larger distances and a large exchange of control signals, WAVE is a good choice. DMG has 19 modulation schemes for Single Carrier Modes and some of them are extremely robust at low SNR. Around SNR 20, it shows lesser packet errors than WAVE. The lower error rate is also evident from the BER values. For use-cases that involve smaller distances and a lot of image data, DMG is preferable. The work, however, does not study the safety and security aspects. Thean alysis and modelling are theoretical being based on literature studies and the necessary parameters provided by VCE. The model needs to be evaluated against field studies and practical measurements with a prototype before implementation inside the paver.

City busses are operated on roads where the GPS signal is weak, because of the tall buildings surrounding these roads. The localization of city busses, needs to therefore rely on alternate technique in order to improve the accuracy. Recent standardization of inter vehicular communication has made this a readily available tool which can be used for localization. This thesis presents an approach towards localization of a city bus by means of vehicular ad hoc network. The two main components of localization by this approach is the initialization of location estimate component, and the real time location estimation component. In particular, the thesis develops the use of minimum mean square estimation for initialization and an extended Kalman filtering approach for real time location estimation. The localization method is mathematically described, considering the operating scenarios of a city bus. The accuracy of the proposed method is mathematically evaluated. The developed localization method is implemented in a simulation tool kit for inter vehicular communication. Simulation experiments were performed for operating scenarios of city bus. The result of initialization by minimum mean square error is compared to that of initialization by GPS, in-terms of localization accuracy. Different setups of road side units are compared in-terms of accuracy and update interval. The results show that the proposed method is feasible for localization of a city bus. This thesis was carried out in association with Scania AB, Södertälje. / Stadsbussar åker på vägar som är omgivna av byggnader, vilket försämrar stadsbussarnas GPSmottagning. Lokaliseringen av stadsbussar måste därför förlita sig på alternativ teknik för att förbättra noggrannheten. Nyligen standardiserad kommunikation mellan fordon har blivit till ett lättillgängligt verktyg som kan användas för lokalisering. Den här uppsatsen presenterar en strategi för lokalisering av en stadsbuss med hjälp av fordonets ad hoc-nätverk. Huvudkomponenterna för lokalisering är en initialiseringskomponent och realtidslägesuppskattningskomponent. Speciellt utvecklar arbetet användningen av minsta medelkvadratberäkning för initialisering och en utvidgad kalmanfiltreringsmetod för realtidslägesuppskattning. Lokaliseringsmetoden beskrivs matematiskt med tanke på driftsscenarierna för en stadsbuss. Noggrannheten hos den föreslagna metoden utvärderas matematiskt. Den utvecklade lokaliseringsmetoden implementeras i ett simuleringsverktyg för kommunikation mellan fordon. Simuleringsexperiment utfördes för driftsscenarier för stadsbussar. Resultatet av initialisering med minsta medelkvadratberäkning jämförs med initialiseringen med GPS, i termer av lokaliseringsnoggrannhet. Olika inställningar av vägrensenheter jämförs med avseende på noggrannhet och uppdateringsintervall. Resultaten visar att den föreslagna metoden är möjlig för lokalisering av en stadsbuss. Denna arbetet genomfördes i samarbete med Scania AB, Södertälje.

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Målet med examensarbetet har varit att samla information åt ett tekniskt konsultföretag för att öka deras kunskap om autonoma system och fordonskommunikation. Statusen på arbetet kring dessa aktiva säkerhetssystem hos olika aktörer och hur systemen implementeras i dagens och framtidens fordon har undersökts genom omfattande litteraturstudier, intervjuer och marknadsanalyser. De autonoma systemen kan samla information från omgivningen genom sensorer och bidra till ett jämnare trafikflöde, ökad säkerhet, lättare bilar och bättre miljö. Genom fordonskommunikationen kan fordon kommunicera med varandra samt infrastrukturen och garantera en säker bilfärd. År 2030 utgörs innerstaden av autonom, elektrifierad kollektivtrafik för att transportera människor på begäran, samtidigt som personbilar till viss del förbjuds. Potentiella behov för människan i en fullt autonom bil har identifierats och diverse produktutvecklingsmetoder har tillämpats för att utforma två konceptuella lösningar för en framtida bilinteriör. Lösningarna visar interaktionen mellan människa och system eftersom underhållning och bekvämlighet blir viktigt i en fullt autonom bil. Respektive lösning är statsägd och rymmer fyra passagerare. I lösningarna är sittplatserna placerade på ett sätt som underlättar kommunikation mellan passagerarna. Passagerarna kan underhållas eller informeras individuellt eller gemensamt via text, ljud och bild. / The goal with this thesis project has been to collect information for a technical consulting company in order to increase their knowledge about autonomous systems and vehicular communication. The status of how various operators work with active safety systems and how the systems are implemented in current and future vehicles has been investigated through extensive literature studies, interviews and market research. The autonomous systems can collect information from the surrounding through sensors and contribute to better traffic efficiency, increased safety, lighter cars and a better environment. Through vehicle communication, the vehicle can communicate with each other in order to guarantee a safe ride. In 2030 the inner city constitutes of autonomous, electrified public transport to transport people on demand, meanwhile private cars are prohibited. Potential needs for the human in a fully, autonomous car has been identified and various product development methods has been applied in order to develop two conceptual solutions for a future car interior. The solutions show the interaction between human and system since entertainment and comfort becomes important in a fully, autonomous car. Each solution is state-owned and holds four passengers. In the solutions, the seats are placed in regard to facilitate communication between the passengers. The passengers can be entertained or informed individually or collectively by text, sound and images.

Time-Triggered Controller Area Network (TTCAN) is a hybrid communication paradigm with combining both time-triggered and event-triggered traffic scheduling. Different from the standard Controller Area Network (CAN), communication in TTCAN is performed according to a pre-computed, fixed (during system run) schedule that is called as TTCAN System Matrix. Thus, communication performance of TTCAN network is directly related to structure of the system matrix, which makes the design of system matrix a crucial process. The study in this thesis consists of the extended work on the development of a systematic approach for system matrix construction. Methods for periodic message scheduling and an approach for aperiodic message scheduling are proposed with the aim of constructing a feasible system matrix, combining three important aspects: message properties, protocol constraints and system performance requirements in terms of designated performance metrics. Also, system matrix design, analyses and performance evaluation are performed on example message sets with the help of two developed software tools.

This work explores possibilities of Car2Car and Car2X communication. It contains survey of system properties, types of transmission messages, etc. It represents architecture of the system and deals with technical expectations and limitations of system. In the light of the fact that this work is created in the time, when development of this system hasn’t finished yet, the work doesn’t contain details which would allow deeper technical view about area of vehicular communication. The work also deals with the possibility of realization of device, communicating with a similar standard. Like the most suitable standard was chosen an IEEE 802.11a. Mobile unit has been realized by single board computer Mini 2440 and communication has been realized by WiFi module OWS451i, which works as AT modem. Mini 2440 and infrastructure server are based on Linux operation system.