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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
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Proceedings ArticleDOI
01 Sep 2008
TL;DR: Modifications to the popular Wiedemann model are addressed and an integration of the modified driving behavior to the traffic simulator VISSIM is presented which thus enables simulations containing accidents.
Abstract: Vehicular ad hoc networks are conceived as a means to increase traffic safety. Primary means to demonstrate their beneficial impact before deployment are computer simulations that comprise communication models, mobility models of vehicles and models of VANET applications. In particular, the movement behavior of vehicles poses questions when evaluating traffic safety since driver models typically do not allow accidents to happen. In this paper we address modifications to the popular Wiedemann model and present an integration of the modified driving behavior to the traffic simulator VISSIM which thus enables simulations containing accidents. Finally, we show in a simulative study how locally available information on the current traffic situation can contribute to safer road traffic. Our contributions represent a first step on how to assess VANETs with respect to traffic safety.

4 citations

Proceedings ArticleDOI
20 Jun 2001
TL;DR: This work proposes an optional, reasonable anonymity service scalable for a large number of subscribers, possible communicating under time constraints, and when integrating the approach in the context of Mobile IP, authentication, authorization and accounting it neither weaken the proposed trust model nor extend the number of involved entities.
Abstract: IP-packets sent over the Internet may reveal detailed information about who communicates with whom. To conceal the identities of sender and receiver, present approaches involve particular network nodes that forward the communication traffic often using cryptographic techniques to en-/decrypt the in-/outgoing data. The current anonymity approaches suite applications that do not have time constraints supporting a limited number of subscribers. These approaches are not suited for a worldwide, possibly time critical scenario with a huge number of subscribers. Diverting all communication traffic over such network nodes would cause bottlenecks and traffic delays. For concealing the relationship of sender and receiver we propose an optional, reasonable anonymity service scalable for a large number of subscribers, possible communicating under time constraints. In addition, when integrating our approach in the context of Mobile IP, authentication, authorization and accounting we neither weaken the proposed trust model nor extend the number of involved entities.

4 citations

Proceedings ArticleDOI
19 Jun 2014
TL;DR: While an extended carrier sensing range is only beneficial for CSMA, the existence and severity of fading is far less detrimental for Self-organizing Time-Division Multiple Access than for CSma.
Abstract: The suitability and performance of medium access protocols in vehicular environments is already being investigated over a long period of time. Carrier Sense Multiple Access (CSMA) has been shown to perform sufficiently well in most situations and being able to support safety and efficiency vehicular applications. Recently, Self-organizing Time-Division Multiple Access (STDMA) is being considered as an alternative and has been shown to coordinate the channel slightly better under certain situations. However, when comparing both protocols the precise details of radio and network conditions and parametrization of the protocols are decisive on which protocol takes a slight lead. Consequently, scenarios can be constructed quite easily in which one protocol is superior over the other one. The focus of this work is thus not to absolutely compare both protocols, but rather to understand the strengths and weaknesses of both protocols in certain situations. In particular, we consider i) to which degree hidden nodes influence the coordination ability, ii) how an extended carrier sensing range is beneficial and iii) how temporary fading influences the performance of both MAC protocols. Our results show that while an extended carrier sensing range is only beneficial for CSMA, the existence and severity of fading is far less detrimental for STDMA than for CSMA.

4 citations

Proceedings ArticleDOI
02 May 2022
TL;DR: A recent spam wave of IP addresses in the Bitcoin P2P network allowed us to estimate the degree distribution of reachable peers and it is shown that simply counting IP addresses overestimates the number of Reachable peers by 15 %.
Abstract: A recent spam wave of IP addresses in the Bitcoin P2P network allowed us to estimate the degree distribution of reachable peers. The resulting distribution indicates that about half of the reachable peers run with Bitcoin Core’s default setting of a maximum of 125 concurrent connections and nearly all connection slots are taken. We validate this result empirically. We use our observations of the spam wave to group IP addresses that belong to the same peer. By doing this grouping, we improve on previous measurements of the number of reachable peers and show that simply counting IP addresses overestimates the number of reachable peers by 15 %. We revalidate previous work by using our observations to estimate the number of unreachable peers.

3 citations


Cited by
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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