Martin Mauve

Heinrich-Heine-Universität Düsseldorf | HHU

In a traditional decision-making process, proposals are made and usually commented on by the participants, and finally a vote is taken. We have found in past public decision-making processes that there are also discussions about negative sides of proposals together with possible improvements of them. We have taken this as an opportunity to model th...

In this demonstration we show how decide can be used to support participatory budgeting. decide allows participants to provide proposals, exchange arguments and prioritize proposals to reach a collective decision. The software has been used by our students to allocate real world money to improve the course of study in computer science at HHU.

In a distributed revision control system (dRCS) such as git, the clear divide between developers with commit rights and outsiders prevents the system from being used in projects where the content is contentious, such as political documents. We design and implement a framework that does allow a large number of users to establish a consensus current...

In this demonstration we will showcase Jebediah, a social bot based on Google's Dialogflow. Jebediah is a front-end to dialog-game execution platforms that enable their seamless integration into popular social networks such as Face-book or Twitter. Users can interact with the social bot using natural language while Jebediah translates the user inpu...

Enabling the reuse of arguments as entities that can be shared across multiple Internet-based discussion platforms and that can be improved upon while they are being used and reused has many benefits ranging from easier participation in an online discussion to increasing the quality of arguments. In this paper we propose a mechanism that is able to...

In this paper, we present D-BAS, a dialog-based online argumentation system, tailored to support e-participation processes. The main idea of D-BAS is to let users exchange proposals and arguments with each other in the form of a time-shifted dialog where arguments are presented and acted upon one-at-a-time. We highlight the key research challenges...

In this paper we report on the results of a field experiment where more than 300 participants used dialog-based online argumenta-tion. The participants were computer science students discussing how to improve the computer science course of studies. At the beginning of the argumentation the participants were informed that the results would be carefu...

A distributed revision control system (dRCS) such as git or mercurial allows users to track changes¹ to a common document.² When multiple users commit, a primary challenge of a dRCS becomes to provide one view of the current repository state.

In this paper we present the web application discuss, which provides a novel approach to embed structured discussions into any web-site. These discussions employ a formal argumentation system in their backend and can be used in addition to or replace existing comment sections. By interacting with the content of the website, we allow to include this...

Current electronic voting systems require an anonymous channel during the voting phase to prevent coercion. Typically, low-latency anonymization-networks like Tor are used for this purpose. In this paper we devise a monitoring attack that allows an attacker to monitor whether participants of an election voted, despite the use of a low-latency netwo...

In this position paper we propose a novel approach to online argumen-tation. It avoids the pitfalls of unstructured systems such as asynchronous threaded discussions and it is usable by any participant without training while still supporting the full complexity of real-world argumentation. The key idea is to let users exchange arguments with each o...

Trace-based simulation of mobile cellular communication requires valid measurements of real-world delay, available data rate and packet loss. These network characteristics need to be measured simultaneously and with high frequency. Previously introduced measurement methods either do not combine the measurement of all three key network characteristi...

Simulation of cellular network communication is complex and typically requires a high degree of knowledge about the underlying network and its parameters. At the same time simulating cellular networks is important for the automotive industry in order to be able to test the feasibility of applications that use car-to-x-communication applications bef...

Denial of Service (DoS) attacks pose a fast-growing threat to network services in the Internet, but also corporate Intranets and public local area networks like Wi-Fi hotspots may be affected. Especially protocols that perform authentication and key exchange relying on expensive public key cryptography are likely to be preferred targets. A well-kno...

Cooperative traffic information systems support the driver of a car in selecting a route, based on traffic information collected by other cars. We propose to use a peer-to-peer network based on Internet access via cellular networks to distribute traffic information between the participants of such a system. This approach avoids the well-known limit...

The trace of a moving object is commonly referred to as a trajectory. This paper considers the spatio-temporal information content of a discrete trajectory in relation to a movement prediction model for the object under consideration. The information content is the minimal amount of information necessary to reconstruct the trajectory, given the mov...

Currently, most of the research on inter-vehicle communication uses the same approach as research on general-purpose networks: protocols and algorithms are developed “bottom-up”, i.e., starting from medium access and addressing, proceeding upwards to the application layer. The set of applications is then evaluated through simulation or real-world e...

Denial of Service (DoS) attacks aiming to exhaust the resources of a server by overwhelming it with bogus requests have become a serious threat. Especially protocols that rely on public key cryptography and perform expensive authentication handshakes may be an easy target. A well-known countermeasure against DoS attacks are client puzzles. The vict...

The transmission of vehicular trajectory information is one basic building block of car-to-car communication. Frequently, this information is transmitted as raw data, i. e., as a sequence of location measurements. In this paper we argue that, due to the laws of physics and the requirement to follow a road, vehicular mobility has very specific chara...

Many applications in vehicular communications require the collection of vehicular position traces. So far this has been done by recording and transmitting unencoded or merely linearly filtered position samples. Depending on the sample frequency and resolution, the resulting data load may be very large, consuming significant storage and transmission...

Fuel-efficient driving is difficult in unknown or complex environments. To aid the driver with this task, we present a novel method of tactical route optimization by calculating a short-term fuel-reduced velocity profile. This profile is based on knowledge of location-dependent velocity profiles that are collected by the vehicles over time and shar...

In this paper we present a novel peer-to-peer system specifically designed to support the unique properties of traffic information systems. We discuss important design decisions, such as update strategies and algorithms for dynamic vehicular route planning. Our system is then assessed using a combination of network (OverSim/OMNeT++) and road traffi...

This working group investigated first steps towards finding a theoretical foundation for inter-vehicle communication. The main outcome is a sketch of a roadmap for future work in this direction.

In this paper we present Scalable Position-Based Multicast (SPBM), a multicast routing protocol for ad-hoc networks. SPBM uses the geographic position of nodes to provide a highly scalable group membership scheme and to forward data packets with a very low overhead. SPBM bases its multicast forwarding decision on whether there are group members loc...

We propose an algorithm for the hierarchical aggregation of observations in dissemination-based, distributed traffic information systems. Instead of transmitting observed parameters directly, we propose soft-state sketches—an extension of Flajolet–Martin sketches—as a probabilistic approximation. This data representation is duplicate insensitive, a...

Road side warning devices play an important role in car-to-car communication. Interestingly however, a detailed experimental evaluation of such devices is missing. Furthermore, although these devices should be able to perform self-positioning to work properly, little attention has been paid to this: mostly, it is assumed that GPS hardware could be...

We introduce a non-interactive RSA time-lock puzzle scheme whose level of difficulty can be arbitrarily chosen by artificially enlarging the public exponent. Solving a puzzle for a message m means for Bob to encrypt m with Alice's public puzzle key by repeated modular squaring. The number of squarings to perform determines the puzzle complexity. Th...

Access point sharing communities are an attractive solution for low-cost global mobile Internet access. However, existing communities all require a central authority in form of a certificate authority or an authentication server. In this paper, we show how such a community network can be created without a central entity. We introduce a mechanism ca...

The analysis of computer network experiments strongly relies on event log files recorded by the participating network nodes during the experiment. Timing related issues play an important role here for a number of central parameters like, e.g., end-to-end delay. As each node uses its local clock to timestamp the events in the log files, the large de...

Many applications in vehicular communications re-quire the collection of vehicular position traces. So far this has been done by recording and transmitting unencoded position samples. Depending on the frequency and resolution of these sam-ples, the resulting data may be very large, consuming significant resources for storage and transmission. In th...

In wireless multihop networks, nodes cooperate to forward data packets. After years of simulation-based research, the next step is the evaluation of this paradigm under real-world conditions. However, due to the distributed nature of such a network in combination with the complex effects of electromagnetic wave propagation, it is extremely difficul...

Searching for witnesses in case of road accidents is a challenging task for the police and involved persons. In this paper, we propose a mechanism that helps to find witnesses. Our solution preserves the potential witnesses' anonymity and gives them a free hand to decide whether to step forward as a witness or not. We analyze the performance of our...

IntroductionObtaining Local MeasurementsInformation TransportSummarizing MeasurementsGeographical Data AggregationConclusion References

Search indices for distributed information are an important building block for many mobile, decentralized applications. However, the network load caused by nodes registering their information in the index can become quite significant especially in mobile networks like vehicular ad-hoc networks (VANETs), where nodes need to register periodically due...

Abstract While mobility in the sense of node movement,has been an intensively studied aspect of mobile ad-hoc networks (MANETs), another aspect of mobility has not yet been subjected to systematic research: nodes may not only move,around but also enter and leave the net- work. In fact, many proposed protocols for MANETs exhibit worst-case behavior...

Abstract— Real-world experiments,in computer,networks,typi- cally result in a set of log files, one for each system involved in the experiment. Each log file contains event timestamps,based on the local clock of the respective system. These clocks are not perfectly accurate, and deviate from each other. For a thorough analysis, however, a common ti...

In this paper we propose a distributed algorithm to detect whether a given node is present or absent in an ad-hoc network. This information is valuable since many proposed protocols and applications for MANETs exhibit worst-case behavior when an intended communication partner is currently not present. Our distributed algorithm improves upon existin...

In this paper we propose a traffic information system based on the distribution of knowledge provided by the cars themselves. Prior work in this area attempted to realize this distribution via vehicular ad-hoc networks, i.e., by direct communication between cars. Such an approach faces serious problems due to capacity constraints, high data dissemi...

Many applications for inter-vehicular communication require a very specific test situation in order to be evaluated during a real world experiment. However, in the currently prevailing free-flow experiments the intended situation for the application may not occur in sufficient frequency to provide statistically significant results. In this paper, w...

The distribution of dynamic information from many sources to many destinations is a key challenge for VANET applications such as cooperative traffic information management or decentralized parking guidance systems. In order for these systems to remain scalable it has been proposed to aggregate the information within the network as it travels from t...

Abstract—The,majority,of security,protocols,employ public,key,cryptography,for authentication,at least in the connection setup phase. However, verifying digital signatures,is an,expensive,task compared,to symmetric key,operations,and,may,become,the target for Denial of Service (DoS) attacks, where the adversary floods the victim host with fake sign...

Ethernet and IP form the basis of the vast majority of LAN installa- tions. But these protocols do not provide comprehensive security mechanisms, and thus give way for a plethora of attack scenarios. In this paper, we introduce a layer 2/3 security extension for LANs, the Cryptographic Link Layer (CLL). CLL provides authentication and confidentiali...

In this paper, we present a methodology and a toolkit to conduct tightly controlled real-world experiments in wireless multihop networks. The main features of our EXC toolkit are a plug-in architecture for easy integration of new functionality, simple scheduling of experiment runs, direct monitoring of experiments, easy management of node mobility,...

This paper investigates the scalable dissemination of data between vehicles. The application context of this work is traffic information systems where cars are not only consumers but also producers of information. The key challenge in those systems is to ensure scalability in an environment where data is provided and requested by all participating...

It has been shown that TCP and TCP-like congestion control are highly problematic in wireless multihop networks. In this paper we present a novel hop-by-hop congestion control protocol that has been tailored to the specific properties of the shared medium. In the proposed scheme, backpressure towards the source node is established implicitly, by pa...

In this paper we investigate how a VANET-based traffic informa- tion system can overcome the two key problems of strictly lim- ited bandwidth and minimal initial deployment. First, we present a domain specific aggregation scheme in order to minimize the re- quired overall bandwidth. Then we propose a genetic algorithm which is able to identify good...

In this paper we present EDAT, a tool designed for the anal- ysis of trace files from network simulations and experiments. The EDAT framework encapsulates analysis steps in exten- sible operators. These can be arbitrarily combined to a flow- based analysis. The core of EDAT is a library of these oper- ators implemented as classes in the scripting l...

Repeatability has most often been neglected in experiments with wireless multihop networks. In this paper, we propose to consider repeatability in a coarse-grained fashion on a topological level. For this, a metric for comparing the simi- larity of topologies in static and mobile setups is presented and used to examine the level of repeatability ac...

A fundamental problem in real-world computer network experiments is that each system uses its own local clock to timestamp events. These clocks are not perfectly accurate, and thus deviate from each other. Event timestamps assigned by different nodes can therefore not immediately be compared, making the analysis of experimental results difficult. T...

In this paper we consider a simplified version of a maximum likelihood time synchronization estimator introduced in [Scheuermann, Kiess, Roos, Jarre, Mauve: "On the time Synchronization of Distributed Log Files in Networks with Local Broadcast Media", IEEE/ACM TON, 2008, accepted for publication]. This simplified variant assumes approximately accur...

In this paper we present Scalable Position-Based Multicast (SPBM), a multicast routing pro- tocol for ad-hoc networks. SPBM uses the geographic position of nodes to provide a highly scalable group membership scheme and to forward data packets in a way that is very robust to changes in the topology of the network. SPBM bases the forwarding decision...

A central problem in today's Internet is unsolicited bulk email: spam. The SMTP protocol lacks a mechanism for verifying the source of a message, and respective protocol extensions are still far from becoming standard. Content-based automatic spam filters are thus often used, and simple origin-based filtering techniques like black- and whitelists a...

Congestion control is a key problem in mobile ad-hoc networks. The standard TCP congestion control mechanism is not able to handle the special properties of a shared wireless multihop channel well. In particular the frequent changes of the network topology and the shared nature of the wireless channel pose significant challenges. Many approaches ha...

The search for free parking places is a promising application for vehicular ad hoc networks (VANETs). In order to guide drivers to a free parking place at their destination, it is necessary to estimate the occupancy state of the parking lots within the destination area at time of arrival. In this paper, we present a model to predict parking lot occ...

Simulation and emulation are valuable techniques for the evaluation of algorithms and protocols used in mobile ad-hoc networks. However, these techniques always require the simplification of real-world properties such as radio characteristics or node mobility. It has been shown that this may lead to results and conclusions which do not reflect the...

In this paper we consider information dissemination in vehicular ad-hoc networks (VANETs) in city scenarios. Information dissemination is an important building block of many proposed VANET applications. These applications need a certain dissemination performance to work satisfactorily. This is critical during the rollout of VANETs, when only few ca...

In the context of vehicular ad-hoc networks (VANETs), a number of highly promising convenience applications have been proposed. These include collecting and distributing information on the traffic situation, distributed monitoring of road and weather conditions, and finding available parking places in a distributed, cooperative manner. Unfortunatel...

We propose an algorithm for the hierarchical aggregation of ob- servations in dissemination-based, distributed traffic information systems. Instead of carrying specific values (e.g., the number of free parking places in a given area), our aggregates contain a mod- ified Flajolet-Martin sketch as a probabilistic approximation. The main advantage of...

While mobility in the sense of node movement has been an inten- sively studied aspect of mobile ad-hoc networks (MANETs), an- other aspect of mobility has not yet been subjected to systematic research: nodes may not only move around but also enter and leave the network. In fact, many proposed protocols for MANETs ex- hibit worst-case behavior when...

In mobile ad-hoc networks, the multicast paradigm is of cen- tral importance. It can help to save scarce medium band- width if packets are to be delivered to multiple destinations. We consider the problem of congestion control for multicast traffic in wireless multihop networks. We propose to apply a congestion control concept which is tailored to...

Sketches—data structures for probabilistic, duplicate insensitive counting—are central building blocks of a number of recently pro- posed network protocols, for example in the context of wireless sensor networks. They can be used to perform robust, distributed data aggregation in a broad range of settings and applications. However, the structure of...

In this position paper we argue that applications for the communica-tion between vehicles do not require the functionality typically offered by mo-bile ad-hoc-networks or wireless sensor networks. Consequently the name Ve-hicular Ad-Hoc Network (VANET) is a misnomer leading practitioners and re-searchers astray. In order to make our point we briefl...

The precision of computer clocks in personal digital assistant (PDA) class devices is typically quite low, they can easily drift more than 5 seconds per day. This is problematic when such devices are used for mobile ad-hoc network experiments, in which it is often necessary that devices distributed over a large area perform a certain action like se...

This chapter introduces the digital ownership idea and its need for peer-to-peer networking due to some shortcomings of digital right management. This chapter is the ground work for the SMARTEX application introduced in the following chapter.

Flooding is a basic mechanism frequently used in mobile ad-hoc networks. In its simplest form flooding is realized by letting each node rebroadcast the flooded packet exactly once. To limit the scope of a flooded data packet, the sender of the packet may use ring flooding. For this, the packet's time-to-live (TTL) field is initially set to n. As th...

Digital content today can be found and accessed almost everywhere -however, not always by its proper owners. Digital rights management so far has been driven by prohibition and patronization. The authors of this article approach digital rights management from an ownership perspective. Being in control, the consumer can now use, share, and trade own...

The MAC layer implementation of today's commodity 802.11 wire-less network devices cannot easily be changed. But many cross-layer protocols for MANETs rely on a modified MAC layer. There-fore it is hard to test such protocols in real world environments. We propose to use a sensor network platform, the ESB sensor nodes, for this purpose. We present...

This paper proposes a topology independent, scalable infor- mation dissemination algorithm for spatio-temporal trac information such as parking place availability using vehicu- lar ad hoc networks (VANET) based on Wireless-LAN IEEE 802.11. The algorithm uses periodic broadcasts for information dissemination. Broadcast redundancy is minimized by eva...

Due to the fact that the MAC layer of commodity 802.11 wireless network devices is usually realized in a proprietary firmware module, it is difficult to conduct real world evaluations of novel MANET cross-layer protocols that require a modified MAC layer. For the REALMAN 2006 demo session, we offer to present a testbed framework based on ESB sensor...

Recording systems and media servers for networked audio and video streams have become an important part of today's Internet. In contrast to this, only a few recording and playback solutions currently exist for the data streams of interactive media applications (e.g., shared whiteboards and distributed virtual environments). So far these solutions a...

Position-based routing, as it is used by protocols like Greedy Perimeter Stateless Routing (GPSR) [5], is very well suited for highly dynamic environments such as inter-vehicle communication on highways. However, it has been discussed that radio obstacles [4], as they are found in urban areas, have a significant negative impact on the performance o...

In this paper, we propose a medium access control (MAC) protocol to support the multi-channel operation for dedicated short range communication (DSRC). In particular, we focus on the challenge of providing potentially high-bandwidth for non-safety applications ...

While most topology control protocols only address limited network mobility, we propose in this paper a quasi-localized topology control algorithm that considers mobility predictions in order to construct and maintain a power efficient topology without ...

Discrete-event network simulation is a major tool for the research and development of mobile ad-hoc networks (MANETs). These simulations are used for debugging, teaching, understanding, and performance-evaluating MANET protocols. For the first three tasks, visualization of the processes occurring in the simulated network is crucial for verification...

Currently, several research groups seek to develop appropriate tools and methodologies for real-world experiments on mobile ad-hoc networks. We argue that this should be done as a community effort rather than as independent projects. Furthermore we present our view on the functionality a good testbed should pro-vide based on reports from other rese...

In recent years, the application of mobile ad hoc networking among vehicles has become an important research field for the automotive industry. Vehicular Ad Hoc Networks (VANETs) are formed by vehicles that are equipped with wireless communication devices based on the standard IEEE 802.11 Wireless-LAN. Embedding mobile ad hoc network devices into v...

Position-based routing has proven to be a scalable and efficient way for packet routing in mobile ad-hoc networks. To enable position-based routing, a node must be able to discover the location of the node it wants to communicate with. This task is typically accomplished by a location service. In this paper, we propose a novel location service call...

Computer games played over the Internet have recently be- come an important class of distributed applications. In this paper we present a novel proxy server-network topology aiming at improved scala- bility of multiplayer games and low latency in client-server data transmis- sion. We present a mechanism to ecien tly synchronize the distributed stat...

Existing position-based unicast routing algorithms, where packets are forwarded in the geographic direction of the destination, require that the forwarding node knows the positions of all neighbors in its transmission range. This information on direct neighbors is gained by observing beacon messages each node sends out periodically. The transmissio...

In this paper we present Position-Based Multicast (PBM), a multicast routing algorithm for mobile ad-hoc networks which does neither require the maintenance of a distribution structure (e.g., a tree or a mesh) nor resorts to flooding of data packets. Instead a forwarding node uses information about the positions of the destinations and its own neig...

Position-based routing in a mobile ad hoc network requires geographic addresses. Thus, a node that wants to send a packet to some target node has to know the target's (approximate) current position. In order to provide each node's position to the other network nodes, a distributed location service has to be used. J. Li et al.

Position-based routing in a mobile ad hoc network requires geographic addresses. Thus, a node that wants to send a packet to some target node has to know the target's (approximate) current position. In order to provide each node's position to the other network nodes, a distributed location service has to be used. J. Li et al. recently put forward a...

In this paper, we propose to apply Contention-Based Forwarding (CBF) to Vehicular Ad Hoc Networks (VANETs). CBF is a greedy positionbased forwarding algorithm that does not require proactive transmission of beacon messages. CBF performance is analyzed using realistic movement patterns of vehicles on a highway. We show by means of simulation that CB...

In this paper, we investigate how consistency can be established for replicated applications changing their state in reaction to user-initiated operations as well as the passing of time. Typical examples of these applications are networked computer games and distributed virtual environments. We give a formal definition of the terms consistency and...

In this paper we investigate how consistency can be established for replicated applications changing their state in reaction to user-initiated operations as well as the passing of time. Typical examples of these applications are networked computer games and distributed virtual environments. We give a formal definition of the terms consistency and c...

In this paper, we present an approach to provide Quality of Service (QoS) for networked mobile gaming. In order to examine the QoS requirements of mobile games, we ported a simple real-time game called GAV (GPL Arcade Volleyball) to a PDA and performed several traffic measurements over both GPRS and UMTS networks. We show that due to high end-to-en...

In this paper, we propose to apply Contention-Based Forwarding (CBF) to Vehicular Ad Hoc Networks (VANETs). CBF is a greedy position-based forwarding algorithm that does not require proactive transmission of beacon messages. CBF performance is analyzed using realistic movement patterns of vehicles on a highway. We show by means of simulation that C...