scispace - formally typeset
Search or ask a question
Author

Frank Dürr

Bio: Frank Dürr is an academic researcher from University of Stuttgart. The author has contributed to research in topics: Mobile computing & Mobile device. The author has an hindex of 25, co-authored 129 publications receiving 2322 citations.


Papers
More filters
Journal ArticleDOI
01 Jan 2014
TL;DR: This paper identifies different protection goals, namely personal information, spatial information (user position), and temporal information (identity/position + time), and gives an overview of basic principles and existing approaches to protect these privacy goals.
Abstract: In recent years, location-based services have become very popular, mainly driven by the availability of modern mobile devices with integrated position sensors. Prominent examples are points of interest finders or geo-social networks such as Facebook Places, Qype, and Loopt. However, providing such services with private user positions may raise serious privacy concerns if these positions are not protected adequately. Therefore, location privacy concepts become mandatory to ensure the user's acceptance of location-based services. Many different concepts and approaches for the protection of location privacy have been described in the literature. These approaches differ with respect to the protected information and their effectiveness against different attacks. The goal of this paper is to assess the applicability and effectiveness of location privacy approaches systematically. We first identify different protection goals, namely personal information (user identity), spatial information (user position), and temporal information (identity/position + time). Secondly, we give an overview of basic principles and existing approaches to protect these privacy goals. In a third step, we classify possible attacks. Finally, we analyze existing approaches with respect to their protection goals and their ability to resist the introduced attacks.

286 citations

Journal ArticleDOI
01 Jan 2005
TL;DR: An overview of existing location models allowing for position, range, and nearest neighbor queries is presented and the classification of location models with respect to application requirements can assist developers in their design decisions.
Abstract: Common queries regarding information processing in ubiquitous computing are based on the location of physical objects. No matter whether it is the next printer, next restaurant, or a friend is searched for, a notion of distances between objects is required. A search for all objects in a certain geographic area requires the possibility to define spatial ranges and spatial inclusion of locations. In this paper, we discuss general properties of symbolic and geometric coordinates. Based on that, we present an overview of existing location models allowing for position, range, and nearest neighbor queries. The location models are classified according to their suitability with respect to the query processing and the involved modeling effort along with other requirements. Besides an overview of existing location models and approaches, the classification of location models with respect to application requirements can assist developers in their design decisions.

270 citations

Proceedings ArticleDOI
19 Oct 2016
TL;DR: The No-wait Packet Scheduling Problem (NW-PSP) is introduced for modelling the scheduling in IEEE Time-sensitive Networks and a Tabu search algorithm for efficient computing of schedules and a schedule compression technique to reduce number of guard bands in schedule are presented.
Abstract: The IEEE Time-sensitive Networking (TSN) Task Group has recently standardized enhancements for IEEE 802.3 networks for enabling it to transport time-triggered traffic (aka scheduled traffic) providing them with stringent bounds on network delay and jitter while also transporting best-effort traffic. These enhancements primarily include dedicating one queue per port of the switch for scheduled traffic along with a programmable gating mechanism that dictates which of the queues are to be considered for transmission. While the IEEE 802.1Qbv standards define these mechanisms to handle scheduled traffic, it stops short of specifying algorithms to compute fine-grained link schedules for the streams of scheduled traffic. Further, the mechanisms in TSN require creation of so-called guard bands to isolate scheduled traffic from the best-effort traffic. These guard bands may potentially result in bandwidth wastage, and hence schedules with lower number of guard bands are preferred. In this paper, we introduce the No-wait Packet Scheduling Problem (NW-PSP) for modelling the scheduling in IEEE Time-sensitive Networks and map it to the No-wait Job-shop Scheduling Problem (NW-JSP), a well-known problem from the field of operational research. In particular, we present a Tabu search algorithm for efficient computing of schedules and a schedule compression technique to reduce number of guard bands in schedule. Our evaluations show that our Tabu search algorithm can compute near-optimal schedules for over 1500 flows and the subsequent schedule compression reduces the number of guard bands on an average by 24%.

187 citations

Journal ArticleDOI
TL;DR: These algorithms exploit the global view of the control plane on the data plane to schedule and route time-triggered flows needed for the dynamic applications in the Industrial Internet of Things (Industry 4.0).
Abstract: Several networking architectures have been developed atop IEEE 802.3 networks to provide real-time communication guarantees for time-sensitive applications in industrial automation systems. The basic principle underlying these technologies is the precise transmission scheduling of time-triggered traffic through the network for providing deterministic and bounded latency and jitter. These transmission schedules are typically synthesized offline (computational time in the order of hours) and remain fixed thereafter, making it difficult to dynamically add or remove network applications. This paper presents algorithms for incrementally adding time-triggered flows in a time-sensitive software-defined network (TSSDN). The TSSDN is a network architecture based on software-defined networking, which provides real-time guarantees for time-triggered flows by scheduling their transmissions on the hosts (network edge) only. These algorithms exploit the global view of the control plane on the data plane to schedule and route time-triggered flows needed for the dynamic applications in the Industrial Internet of Things (Industry 4.0). The evaluations show that these algorithms can compute incremental schedules for time-triggered flows in subseconds with an average relative optimality of 68%.

148 citations

Proceedings ArticleDOI
18 Mar 2019
TL;DR: To facilitate the analysis of TSN networks, TSN-specific extensions to the popular OMNeT++/INET framework for network simulations are presented including, in particular, the time-triggered scheduling mechanism of IEEE Std 802.1Qbv.
Abstract: IEEE 802.1 Time-sensitive Networking (TSN) enables real-time communication with deterministically bounded network delay and jitter over standard IEEE 802.3 networks (“Ethernet”). In particular, TSN specifies a time-triggered scheduling mechanism in IEEE Std 802.1Qbv implemented by switches to control when outgoing queues get access to switch ports. Besides this time-triggered scheduling mechanism, other scheduling mechanisms can be active in the network at the same time including priority queuing and a credit-based shaper. Moreover, further supporting mechanisms such as the possibility to interrupt frames already in transmission (frame preemption) are specified by the TSN standards. Overall, this leads to a complex network infrastructure transporting both, real-time and non-real-time traffic in one converged network, making it hard to analyze the behavior of converged networks. To facilitate the analysis of TSN networks, we present TSN-specific extensions to the popular OMNeT++/INET framework for network simulations in this paper including, in particular, the time-triggered scheduling mechanism of IEEE Std 802.1Qbv. Besides the design of the TSN simulator, we present a proof-of-concept implementation and exemplary evaluation of TSN networks.

104 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

Journal ArticleDOI

6,278 citations

01 Apr 2003
TL;DR: The EnKF has a large user group, and numerous publications have discussed applications and theoretical aspects of it as mentioned in this paper, and also presents new ideas and alternative interpretations which further explain the success of the EnkF.
Abstract: The purpose of this paper is to provide a comprehensive presentation and interpretation of the Ensemble Kalman Filter (EnKF) and its numerical implementation. The EnKF has a large user group, and numerous publications have discussed applications and theoretical aspects of it. This paper reviews the important results from these studies and also presents new ideas and alternative interpretations which further explain the success of the EnKF. In addition to providing the theoretical framework needed for using the EnKF, there is also a focus on the algorithmic formulation and optimal numerical implementation. A program listing is given for some of the key subroutines. The paper also touches upon specific issues such as the use of nonlinear measurements, in situ profiles of temperature and salinity, and data which are available with high frequency in time. An ensemble based optimal interpolation (EnOI) scheme is presented as a cost-effective approach which may serve as an alternative to the EnKF in some applications. A fairly extensive discussion is devoted to the use of time correlated model errors and the estimation of model bias.

2,975 citations

Journal ArticleDOI
TL;DR: This paper surveys context awareness from an IoT perspective and addresses a broad range of techniques, methods, models, functionalities, systems, applications, and middleware solutions related to context awareness and IoT.
Abstract: As we are moving towards the Internet of Things (IoT), the number of sensors deployed around the world is growing at a rapid pace. Market research has shown a significant growth of sensor deployments over the past decade and has predicted a significant increment of the growth rate in the future. These sensors continuously generate enormous amounts of data. However, in order to add value to raw sensor data we need to understand it. Collection, modelling, reasoning, and distribution of context in relation to sensor data plays critical role in this challenge. Context-aware computing has proven to be successful in understanding sensor data. In this paper, we survey context awareness from an IoT perspective. We present the necessary background by introducing the IoT paradigm and context-aware fundamentals at the beginning. Then we provide an in-depth analysis of context life cycle. We evaluate a subset of projects (50) which represent the majority of research and commercial solutions proposed in the field of context-aware computing conducted over the last decade (2001-2011) based on our own taxonomy. Finally, based on our evaluation, we highlight the lessons to be learnt from the past and some possible directions for future research. The survey addresses a broad range of techniques, methods, models, functionalities, systems, applications, and middleware solutions related to context awareness and IoT. Our goal is not only to analyse, compare and consolidate past research work but also to appreciate their findings and discuss their applicability towards the IoT.

2,542 citations

Journal ArticleDOI
TL;DR: A comprehensive survey of numerous IPSs, which include both commercial products and research-oriented solutions are given, and the trade-offs among these systems are outlined from the viewpoint of a user in a PN.
Abstract: Recently, indoor positioning systems (IPSs) have been designed to provide location information of persons and devices. The position information enables location-based protocols for user applications. Personal networks (PNs) are designed to meet the users' needs and interconnect users' devices equipped with different communications technologies in various places to form one network. Location-aware services need to be developed in PNs to offer flexible and adaptive personal services and improve the quality of lives. This paper gives a comprehensive survey of numerous IPSs, which include both commercial products and research-oriented solutions. Evaluation criteria are proposed for assessing these systems, namely security and privacy, cost, performance, robustness, complexity, user preferences, commercial availability, and limitations.We compare the existing IPSs and outline the trade-offs among these systems from the viewpoint of a user in a PN.

1,538 citations