scispace - formally typeset
Search or ask a question
Author

Hannes Hartenstein

Bio: Hannes Hartenstein is an academic researcher from Karlsruhe Institute of Technology. The author has contributed to research in topics: Vehicular ad hoc network & Wireless ad hoc network. The author has an hindex of 55, co-authored 234 publications receiving 14515 citations. Previous affiliations of Hannes Hartenstein include University of Mannheim & University of Freiburg.


Papers
More filters
Proceedings ArticleDOI
17 Nov 2013
TL;DR: The GRABEX-method is applied to mine breadcrumb trails and is the first to describe an applicable solution to this problem and is presented as a novel approach to the problem.
Abstract: In order to interact with a Web site, humans must be able to distinguish and understand the purposes of different page blocks, e.g. header, navigation bar or content area. In case of navigational blocks, the block type determines the functionality of the hyperlinks it contains. For example, the hyperlinks in the main menu block represent the main topics of a site while the hyperlinks in a breadcrumb trail show the location in the content hierarchy. Hence, mining navigational blocks of specific types can provide valuable input for applications in the fields of crawling, ranking or presenting search results. However, analyzing visual features in order to identify specific navigational blocks as humans do is a difficult, resource-consuming task and a general solution does not exist yet. In this paper, we propose a novel approach to the problem and present the Graph-based block extraction method (GRABEX) that can be adapted to classify different types of navigational blocks. The fundamental concept is that a separate graph-based link-analysis is conducted for groups of blocks. Each block group consists of blocks from different pages that have similar CSS class attributes. This allows discovering navigational blocks of specific types, e.g. breadcrumb trails, without analyzing any presentational features. We apply our method to mine breadcrumb trails and are the first to describe an applicable solution to this problem. In an extensive evaluation including 700 different sites, the GRABEX-method performed with perfect precision and high recall.

6 citations

Proceedings ArticleDOI
23 Sep 2011
TL;DR: It is argued that the vehicular networking community might need to extend its perspective -- from bits and packets towards information-centric models -- when assessing efficiency gains in large scale scenarios, thereby providing a multi-scale approach as it is done in various disciplines.
Abstract: Inter-vehicle communication with the objective to increase safety and efficiency of our transportation network has been studied extensively in the last few years. However, we are still struggling in answering the fundamental question of to which extent can inter-vehicle communication improve our wide-area transportation network that consists of more than several cities?. In this position paper we discuss from a methodological point of view and by analyzing recent trends how the VANET community could move forward with respect to evaluation methodologies. Based on our observations, we argue that the vehicular networking community might need to extend its perspective -- from bits and packets towards information-centric models -- when assessing efficiency gains in large scale scenarios, thereby providing a multi-scale approach as it is done in various disciplines. We further believe that the community should join forces to convert existing results as well as current and upcoming measurements to provide information-centric models of inter-vehicular communication. We finally propose a modeling approach that could serve as a foundation for future joint efforts and which might take us one step closer to the answer of the fundamental question stated above.

6 citations

Proceedings ArticleDOI
01 Nov 2012
TL;DR: This paper uses a high fidelity network simulator and resolves the two reasons that may cause incoordination - either simultaneous transmission times or hidden terminal situations - and concludes that CSMA is able to effectively coordinate multiple access in vehicular radio channels as long as the load offered to the channel does not approach the maximum capacity.
Abstract: The first generation of inter-vehicle communication networks will most likely be based on the IEEE 802.11p standard. That is, they are going to deploy Carrier Sense Multiple Access (CSMA) to coordinate channel access among neighboring vehicles. Recently, concerns have been raised that fast-fading propagation conditions, i.e. a time- and frequency-selective fading as reported by several measurement campaigns in highway environments, might challenge the effectiveness of CSMA. These concerns also lead to the situation that alternative medium access control solutions are being discussed in standardization bodies. In this paper, we evaluate whether these concerns are justified or not. In comparison to previous studies, we use a high fidelity network simulator to study the extent by which the effectiveness of CSMA is reduced if such fading propagation conditions are considered. We also resolve the two reasons that may cause incoordination - either simultaneous transmission times or hidden terminal situations - and conclude that CSMA is able to effectively coordinate multiple access in vehicular radio channels as long as the load offered to the channel does not approach the maximum capacity.

6 citations

DOI
01 Jan 2014
TL;DR: Leading experts in the field of vehicular networking met in Dagstuhl to discuss the current state of the art and, most importantly, the open challenges in R&D from both an scientific and an industry point of view.
Abstract: "Inter-Vehicular Communication -- Quo Vadis?". With this question in mind, leading experts in the field of vehicular networking met in Dagstuhl to discuss the current state of the art and, most importantly, the open challenges in R&D from both an scientific and an industry point of view. After more than a decade of research on vehicular networks, the experts very seriously asked the question whether all of the initial research issues had been solved so far. It turned out that the perspective changed in the last few years, mainly thanks to the ongoing field operational tests in Europe and the U.S. The results point to new research directions and new challenges that need to be solved for a second generation of vehicular networking applications and protocols. In four working groups, the experts studied these new challenges and derived recommendations that are also very helpful for the respective funding organizations.

5 citations


Cited by
More filters
Proceedings ArticleDOI
22 Jan 2006
TL;DR: Some of the major results in random graphs and some of the more challenging open problems are reviewed, including those related to the WWW.
Abstract: We will review some of the major results in random graphs and some of the more challenging open problems. We will cover algorithmic and structural questions. We will touch on newer models, including those related to the WWW.

7,116 citations

Proceedings ArticleDOI
22 Aug 2005
TL;DR: A new routing scheme, called Spray and Wait, that "sprays" a number of copies into the network, and then "waits" till one of these nodes meets the destination, which outperforms all existing schemes with respect to both average message delivery delay and number of transmissions per message delivered.
Abstract: Intermittently connected mobile networks are sparse wireless networks where most of the time there does not exist a complete path from the source to the destination. These networks fall into the general category of Delay Tolerant Networks. There are many real networks that follow this paradigm, for example, wildlife tracking sensor networks, military networks, inter-planetary networks, etc. In this context, conventional routing schemes would fail.To deal with such networks researchers have suggested to use flooding-based routing schemes. While flooding-based schemes have a high probability of delivery, they waste a lot of energy and suffer from severe contention, which can significantly degrade their performance. Furthermore, proposed efforts to significantly reduce the overhead of flooding-based schemes have often be plagued by large delays. With this in mind, we introduce a new routing scheme, called Spray and Wait, that "sprays" a number of copies into the network, and then "waits" till one of these nodes meets the destination.Using theory and simulations we show that Spray and Wait outperforms all existing schemes with respect to both average message delivery delay and number of transmissions per message delivered; its overall performance is close to the optimal scheme. Furthermore, it is highly scalable retaining good performance under a large range of scenarios, unlike other schemes. Finally, it is simple to implement and to optimize in order to achieve given performance goals in practice.

2,712 citations

Journal ArticleDOI
John Kenney1
16 Jun 2011
TL;DR: The content and status of the DSRC standards being developed for deployment in the United States are explained, including insights into why specific technical solutions are being adopted, and key challenges remaining for successful DSRC deployment.
Abstract: Wireless vehicular communication has the potential to enable a host of new applications, the most important of which are a class of safety applications that can prevent collisions and save thousands of lives. The automotive industry is working to develop the dedicated short-range communication (DSRC) technology, for use in vehicle-to-vehicle and vehicle-to-roadside communication. The effectiveness of this technology is highly dependent on cooperative standards for interoperability. This paper explains the content and status of the DSRC standards being developed for deployment in the United States. Included in the discussion are the IEEE 802.11p amendment for wireless access in vehicular environments (WAVE), the IEEE 1609.2, 1609.3, and 1609.4 standards for Security, Network Services and Multi-Channel Operation, the SAE J2735 Message Set Dictionary, and the emerging SAE J2945.1 Communication Minimum Performance Requirements standard. The paper shows how these standards fit together to provide a comprehensive solution for DSRC. Most of the key standards are either recently published or expected to be completed in the coming year. A reader will gain a thorough understanding of DSRC technology for vehicular communication, including insights into why specific technical solutions are being adopted, and key challenges remaining for successful DSRC deployment. The U.S. Department of Transportation is planning to decide in 2013 whether to require DSRC equipment in new vehicles.

1,866 citations

Posted Content
TL;DR: This paper defines and explores proofs of retrievability (PORs), a POR scheme that enables an archive or back-up service to produce a concise proof that a user can retrieve a target file F, that is, that the archive retains and reliably transmits file data sufficient for the user to recover F in its entirety.
Abstract: In this paper, we define and explore proofs of retrievability (PORs). A POR scheme enables an archive or back-up service (prover) to produce a concise proof that a user (verifier) can retrieve a target file F, that is, that the archive retains and reliably transmits file data sufficient for the user to recover F in its entirety.A POR may be viewed as a kind of cryptographic proof of knowledge (POK), but one specially designed to handle a large file (or bitstring) F. We explore POR protocols here in which the communication costs, number of memory accesses for the prover, and storage requirements of the user (verifier) are small parameters essentially independent of the length of F. In addition to proposing new, practical POR constructions, we explore implementation considerations and optimizations that bear on previously explored, related schemes.In a POR, unlike a POK, neither the prover nor the verifier need actually have knowledge of F. PORs give rise to a new and unusual security definition whose formulation is another contribution of our work.We view PORs as an important tool for semi-trusted online archives. Existing cryptographic techniques help users ensure the privacy and integrity of files they retrieve. It is also natural, however, for users to want to verify that archives do not delete or modify files prior to retrieval. The goal of a POR is to accomplish these checks without users having to download the files themselves. A POR can also provide quality-of-service guarantees, i.e., show that a file is retrievable within a certain time bound.

1,783 citations

Journal ArticleDOI
01 Jan 2007
TL;DR: This paper provides a set of security protocols, it is shown that they protect privacy and it is analyzed their robustness and efficiency, and describes some major design decisions still to be made.
Abstract: Vehicular networks are very likely to be deployed in the coming years and thus become the most relevant form of mobile ad hoc networks. In this paper, we address the security of these networks. We provide a detailed threat analysis and devise an appropriate security architecture. We also describe some major design decisions still to be made, which in some cases have more than mere technical implications. We provide a set of security protocols, we show that they protect privacy and we analyze their robustness and efficiency.

1,550 citations