A main distinguishing feature of a wireless network compared with a wired network is its broadcast nature, in which the signal transmitted by a node may reach several other nodes, and a node may receive signals from several other nodes simultaneously. Rather than a blessing, this feature is treated more as an interference-inducing nuisance in most wireless networks today (e.g., IEEE 802.11). The goal of this paper is to show how the concept of network coding can be applied at the physical layer to turn the broadcast property into a capacity-boosting advantage in wireless ad hoc networks. Specifically, we propose a physical-layer network coding (PNC) scheme to coordinate transmissions among nodes. In contrast to "straightforward" network coding which performs coding arithmetic on digital bit streams after they have been received, PNC makes use of the additive nature of simultaneously arriving electromagnetic (EM) waves for equivalent coding operation. PNC can yield higher capacity than straight-forward network coding when applied to wireless networks. We believe this is a first paper that ventures into EM-wave-based network coding at the physical layer and demonstrates its potential for boosting network capacity. PNC opens up a whole new research area because of its implications and new design requirements for the physical, MAC, and network layers of ad hoc wireless stations. The resolution of the many outstanding but interesting issues in PNC may lead to a revolutionary new paradigm for wireless ad hoc networking.

Hot topic: physical-layer network coding

A secure data parser is provided that may be integrated into any suitable system for securely storing and communicating data. The secure data parser parses data and then splits the data into multiple portions that are stored or communicated distinctly. Encryption of the original data, the portions of data, or both may be employed for additional security. The secure data parser may be used to protect data in motion by splitting original data into portions of data, that may be communicated using multiple communications paths.

Secure data parser method and system

Vehicular Ad hoc Network (VANET), a subclass of mobile Ad Hoc networks (MANETs), is a promising approach for future intelligent transportation system (ITS). These networks have no fixed infrastructure and instead rely on the vehicles themselves to provide network functionality. However, due to mobility constraints, driver behavior, and high mobility, VANETs exhibit characteristics that are dramatically different from many generic MANETs. This article provides a comprehensive study of challenges in these networks, which we concentrate on the problems and proposed solutions. Then we outline current state of the research and future perspectives. With this article, readers can have a more thorough understanding of vehicle ad hoc networking and the research trends in this area.

http://webpages.iust.ac.ir/mahfathy/_vti_pvt/Papers/ehicular%20Ad%20Hoc%20Networks%20(VANETs)%20Challenges%20and%20Perspectives.pdf

Vehicular Ad Hoc Networks (VANETs): Challenges and Perspectives

Inter-vehicle communication (IVC) systems (i.e., systems not relying on roadside infrastructure) have the potential to radically improve the safety, efficiency, and comfort of everyday road travel. Their main advantage is that they bypass the need for expensive infrastructure; their major drawback is the comparatively complex networking protocols and the need for significant penetration before their applications can become effective. In this article we present several major classes of applications and the types of services they require from an underlying network. We then proceed to analyze existing networking protocols in a bottom-up fashion, from the physical to the transport layers, as well as security aspects related to IVC systems. We conclude the article by presenting several projects related to IVC as well as a review of common performance evaluation techniques for IVC systems.

/pdf/inter-vehicle-communication-systems-a-survey-4dcec4ylxn.pdf

Inter-vehicle communication systems: a survey

Cooperative adaptive cruise control (CACC) systems have the potential to increase traffic throughput by allowing smaller headway between vehicles and moving vehicles safely in a platoon at a harmonized speed. CACC systems have been attracting significant attention from both academia and industry since connectivity between vehicles will become mandatory for new vehicles in the USA in the near future. In this paper, we review three basic and important aspects of CACC systems: communications, driver characteristics, and controls to identify the most challenging issues for their real-world deployment. Different routing protocols that support the data communication requirements between vehicles in the CACC platoon are reviewed. Promising and suitable protocols are identified. Driver characteristics related issues, such as how to keep drivers engaged in driving tasks during CACC operations, are discussed. To achieve mass acceptance, the control design needs to depict real-world traffic variability such as communication effects, driver behavior, and traffic composition. Thus, this paper also discusses the issues that existing CACC control modules face when considering close to ideal driving conditions.

A Review of Communication, Driver Characteristics, and Controls Aspects of Cooperative Adaptive Cruise Control (CACC)

Traffic and travel information (TTI) systems in use today are based on a centralized structure. Sensors along the roadside monitor traffic density and transmit the results to a central unit where a situation analysis of the global traffic scenario is performed. The resulting traffic information is made available to drivers via broadcast service or alternatively on demand via cellular phone. Within the FleetNet project, a completely different proposal to establish a powerful traffic information system is developed and analyzed, which is based in inter-vehicle communications (IVC). All vehicles are part of a self-organizing traffic information system (SOTIS): each vehicle monitors the locally observed traffic situation by recurrently receiving data packets with detailed information from other vehicles. A traffic situation analysis if performed in each individual vehicle and the result is transferred via wireless data-link to all surrounding vehicles in the local neighborhood. No sensors along the highways, no central units and no local broadcast stations or cellular networks are needed, which minimizes infrastructure costs. The complete system can be easily avoided completely. Simulation results demonstrate that the proposed SOTIS technique can easily provide detailed information for each vehicle with an individual information range of more than 50 km from the current position with high accuracy and low delay. Even in situations where only a small fraction of all vehicles (e.g. 2%) is equipped with the SOTIS technology, the full functionality of a traffic information system is available.

SOTIS - a self-organizing traffic information system

Conventional Traffic and Travel Information (TTI) systems are based on a centralized structure: Sensors deployed at the roadside monitor the traffic and transmit the results to a central unit, which performs a situation analysis. TTI is made available to the drivers via broadcast service (e.g. TMC/RDS) or on demand via cellular phone. In contrast to this centralized approach. a decentralized, Self-Organizing Traffic Information System (SOTIS) based on Inter-Vehicle Communication (IVC) has many advantages: It requires no expensive infrastructure. can provide detailed information for the local area with low delay and is available everywhere. In such an IVC based decentralized system, TTI is sensed by each individual vehicle. The information is analyzed, combined with TTI received from other vehicles and the results are distributed using recurring broadcast packets. In this paper; an adaptive broadcast scheme for efficient TTI distribution called Provoked Broadcast is presented. The algorithm favors the propagation of significant TTI changes within the self-organizing network. Nodes adapt their communication behavior to the local environment and avoid redundant transmissions. The performance of the proposed scheme is evaluated by using simulations of typical traffic scenarios. Compared to a strictly periodic broadcast, the new scheme decreases the average error of information available at an individual vehicle and still requires significantly less bandwidth.

Adaptive broadcast for travel and traffic information distribution based on inter-vehicle communication

A method and arrangement for controlling a system of multiple traffic signals for regulating the traffic of vehicles is described. Traffic data is transmitted by wireless transmission to traffic data processing units assigned individually to a locally limited group of traffic signals, and each traffic data processing unit performs an analysis of the local traffic situation for the environment of the locally limited group of traffic signals up to, at the maximum, the neighboring locally limited groups of traffic signals.

Method and arrangement for controlling a system of multiple traffic signals

Within the FleetNet project an ad hoc radio network for intervehicle communications (IVC) and road telematics is being developed. For the air interface, the framework of the UMTS Terrestrial Radio Access time division duplex (UTRA TDD) standard has been selected as the most promising candidate. The requirements and challenges for synchronization in an ad hoc network with rapidly changing topology and high velocities are discussed. Solutions for synchronization in ad hoc networks based on UTRA TDD are proposed and evaluated by means of link-level simulations. The results indicate promising performance with only minor changes to the UTRA TDD standard specifications.

Synchronization in ad hoc networks based on UTRA TDD

The FleetNet project aims at the development of a wireless ad hoc network for inter-vehicle communications (IVC). As a basis for the air-interface, the framework of the UMTS terrestrial radio access time division duplex (UTRA TDD) has been selected as the most promising candidate. Since UTRA TDD was developed for operation in a cellular network structure, modifications are required to enable mobile nodes to communicate in ad hoc mode without the existence of base stations. In particular, this comprises changes to physical (PHY) layer, medium access control (MAC) and radio resource management (RRM). The focus of this paper is the PHY layer of the air-interface and the resulting challenges in highly dynamic vehicular environments. The performance of the UTRA TDD ad hoc mode is assessed and compared to the IEEE 802.11b standard using link-level simulations. Results indicate that the UTRA TDD ad hoc PHY outperforms IEEE 802.11b in a typical highway scenario with very large relative velocities. In urban traffic environments with strong multipath propagation, IEEE 802.11b is not able to meet the required performance in terms of packet losses.

Performance of UTRA TDD ad hoc and IEEE 802.11b in vehicular environments

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Ruediger Halfmann

Author Tools

Chat about Author