이기종 차량간 통신 공존 환경에서의 효율적인 메시지 중계 기법

학위논문(석사)--서울대학교 대학원 :공과대학 전기·정보공학부,2019. 8. 최성현.Today, there exist two types of vehicular communication technology, namely, Long Term Evolution-based vehicle-to-vehicle (LTE-V2V) and dedicated short range communications (DSRC). Although many studies dealing with vehicular communication have been conducted, the situation where separate groups of vehicles using different communication technologies coexist has never been studied. In the coexistence situation, the communication inability issue between vehicles using different communication technologies is raised. To resolve the problem, we propose a relaying system, called Nearest-first, where hybrid user equipments (UEs), which are equipped with both DSRC and LTE-V2V modules, are considered. When a hybrid UE receives a cooperative awareness message (CAM), the UE relays the CAM using the other communication technology.최근 주목을 받고 있는 vehicule-to-vehicle(V2V)통신 기술에는 dedicated short-range communications(DSRC), Long Term Evolution-based vehicle-to-vehicle(LTE-V2V)기술, 이렇게 두 가지 기술이 있다. 지금까지 많은 V2V 통신 기술 연구가 진행되었지만, 다른 통신 기술들을 지원하는 차량들이 혼재하는 상황에 대한 연구는 진행되어진 바가 없다. 두 통신 기술이 혼재하는 상황에서는, 다른 통신 기술을 지원하는 차량 간에 통신 불능 문제가 대두될 수 있다. 이 잠재적인 문제를 해결하기 위해서, 우리는 Nearest-first라는 이름의 메시지 중계 방식을 제안했다. Nearest-first에서는, DSRC와 LTE-V2V 모두를 지원하는 차량의 존재를 가정하고, 이를 hybrid UE라고 부른다. Hybrid UE가 차량 안전 정보를 담은 cooperative awareness message(CAM)을 받으면, hybrid UE는 그 CAM이 원래 전송되어진 통신 기술과 다른 통신 기술로 중계한다. 우리는 사실적인 차량 움직임과 도로 상황을 포함한 다양한 환경에서 시뮬레이션을 수행했다. 시뮬레이션 결과, Nearest-first는 현재 사용되어지고 있는 차량간 통신에서의 중계 기법에 비해 유효 통신 거리를 91% 증가시켰다.1 Introduction 1 2 RelatedWork 5 2.1 Relaying in VANET 5 2.1.1 Farthest-first Relaying . 6 2.1.2 Other Delay-based Relaying Methods 6 2.2 Coexistence of Vehicular Communications 7 3 Preliminaries 9 3.1 DSRC 9 3.2 LTE-V2V 11 3.3 Industry Trends and Motivation 11 4 System Model 14 4.1 Baseline Relaying Scheme 15 4.1.1 Relaying Packets from DSRC UE to LTE-V2V 17 4.1.2 Relaying Packets from LTE-V2V UE to DSRC 17 5 Proposed Scheme 19 5.1 Motivation for Nearest-first 19 5.2 Common Rules for Relaying Packets Both from DSRC UEs and LTEV2V UEs 20 5.3 Nearest-first for Relaying Packets from DSRC UEs 22 5.4 Nearest-first for Relaying Packets from LTE-V2V UEs 25 6 Evaluation 27 6.1 Simulation Environments 27 6.2 Performance Metrics 31 6.3 Advantage of Relaying from Network Operator Perspective 33 6.4 Overall Performance Comparison 34 7 Conclusion 43 Abstract (In Korean) 50 감사의 글 52Maste

Distributed Adaptation Techniques for Connected Vehicles

In this PhD dissertation, we propose distributed adaptation mechanisms for connected vehicles to deal with the connectivity challenges. To understand the system behavior of the solutions for connected vehicles, we first need to characterize the operational environment. Therefore, we devised a large scale fading model for various link types, including point-to-point vehicular communications and multi-hop connected vehicles. We explored two small scale fading models to define the characteristics of multi-hop connected vehicles. Taking our research into multi-hop connected vehicles one step further, we propose selective information relaying to avoid message congestion due to redundant messages received by the relay vehicle. Results show that the proposed mechanism reduces messaging load by up to 75% without sacrificing environmental awareness. Once we define the channel characteristics, we propose a distributed congestion control algorithm to solve the messaging overhead on the channels as the next research interest of this dissertation. We propose a combined transmit power and message rate adaptation for connected vehicles. The proposed algorithm increases the environmental awareness and achieves the application requirements by considering highly dynamic network characteristics. Both power and rate adaptation mechanisms are performed jointly to avoid one result affecting the other negatively. Results prove that the proposed algorithm can increase awareness by 20% while keeping the channel load and interference at almost the same level as well as improve the average message rate by 18%. As the last step of this dissertation, distributed cooperative dynamic spectrum access technique is proposed to solve the channel overhead and the limited resources issues. The adaptive energy detection threshold, which is used to decide whether the channel is busy, is optimized in this work by using a computationally efficient numerical approach. Each vehicle evaluates the available channels by voting on the information received from one-hop neighbors. An interdisciplinary approach referred to as entropy-based weighting is used for defining the neighbor credibility. Once the vehicle accesses the channel, we propose a decision mechanism for channel switching that is inspired by the optimal flower selection process employed by bumblebees foraging. Experimental results show that by using the proposed distributed cooperative spectrum sensing mechanism, spectrum detection error converges to zero

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Platooning is an application where a group of vehicles move one after each other in close proximity, acting jointly as a single physical system. The scope of platooning is to improve safety, reduce fuel consumption, and increase road use efficiency. Even if conceived several decades ago as a concept, based on the new progress in automation and vehicular networking platooning has attracted particular attention in the latest years and is expected to become of common implementation in the next future, at least for trucks.The platoon system is the result of a combination of multiple disciplines, from transportation, to automation, to electronics, to telecommunications. In this survey, we consider the platooning, and more specifically the platooning of trucks, from the point of view of wireless communications. Wireless communications are indeed a key element, since they allow the information to propagate within the convoy with an almost negligible delay and really making all vehicles acting as one. Scope of this paper is to present a comprehensive survey on connected vehicles for the platooning application, starting with an overview of the projects that are driving the development of this technology, followed by a brief overview of the current and upcoming vehicular networking architecture and standards, by a review of the main open issues related to wireless communications applied to platooning, and a discussion of security threats and privacy concerns. The survey will conclude with a discussion of the main areas that we consider still open and that can drive future research directions.(c) 2022 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Radio shadowing in vehicle-to-vehicle communication at urban intersections : a measurement and simulation-based evaluation

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Investigation of Shadow Matching for GNSS Positioning in Urban Canyons

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Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin

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