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arXiv 2020年

作者： Ahmadi, Samim Hauffen, Jan Christian Kästner, Linh Jung, Peter Caire, Giuseppe Ziegler, Mathias Bundesanstalt für Materialforschung und -prüfung Berlin Germany Chair Industry Grade Networks and Clouds Faculty of Electrical Engineering and Computer Science Berlin Institute of Technology Berlin Germany Chair Communication and Information Theory Berlin Institute of Technology Berlin Germany

Block-sparse regularization is already well-known in active thermal imaging and is used for multiple measurement based inverse problems. The main bottleneck of this method is the choice of regularization parameters which differs for each experiment. To avoid time-consuming manually selected regularization parameter, we propose a learned block-sparse optimization approach using an iterative algorithm unfolded into a deep neural network. More precisely, we show the benefits of using a learned block iterative shrinkage thresholding algorithm that is able to learn the choice of regularization parameters. In addition, this algorithm enables the determination of a suitable weight matrix to solve the underlying inverse problem. Therefore, in this paper we present the algorithm and compare it with state of the art block iterative shrinkage thresholding using synthetically generated test data and experimental test data from active thermography for defect reconstruction. Our results show that the use of the learned block-sparse optimization approach provides smaller normalized mean square errors for a small fixed number of iterations than without learning. Thus, this new approach allows to improve the convergence speed and only needs a few iterations to generate accurate defect reconstruction in photothermal super resolution imaging. © 2020, CC BY.

关键词： Mean square error

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Why We Should not Talk about 6G

arXiv

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arXiv 2020年

作者： Fitzek, Frank H.P. Seeling, Patrick Centre for Tactile Internet with Human-in-the-Loop and the Deutsche Telekom Chair of Communication Networks Technische Universität Dresden Dresden Saxony Germany Department of Computer Science Central Michigan University Mount PleasantMI United States

While 5G mobile communication systems are currently in deployment, researchers around the world have already started to discuss 6G technology and funding agencies started their first programs with a 6G label. Although it may seem like a good idea from a historical point of view with returning generations every decade, this contribution will show that there is a great risk of introducing 6G labels at this time. While the reasons to not talk about 6G yet are manifold, some of the more dominant ones are i.) there exists a lack of real technology advancements introduced by a potential 6G system;ii.) the flexibility of the 5G communication system introduced by softwarization concepts, such as in the Internet community, allows for daily updates;and iii.) introducing widespread 6G discissions can have a negative impact on the deployment and evolution of 5G with completely new business cases and customer ecosystems compared to its predecessors. Finally, as we do not believe that 5G is the end of our journey, we will provide an outlook on the future of mobile communication systems, independent of the current mainstream discussion. Copyright © 2020, The Authors. All rights reserved.

关键词： 5G mobile communication systems

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Mobility-aware joint service placement and routing in space-air-ground integrated networks

arXiv

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arXiv 2019年

作者： Varasteh, Amir Hofmann, Sandra Deric, Nemanja He, Mu Schupke, Dominic Kellerer, Wolfgang Machuca, Carmen Mas Chair of Communication Networks Department of Electrical and Computer Engineering Technical University of Munich Germany Airbus Munich Germany

People desire to be connected, no matter where they are. Recently, providing Internet access to on-board passengers has received a lot of attention from both industry and academia. However, in order to guarantee an acceptable Quality of Service (QoS) for the passenger services with low incurred cost, the path to route the services, as well as the datacenter (DC) to deploy the services should be carefully determined. This problem is challenging, due to different types of Air-to-Ground (A2G) connections, i.e., satellites and Direct Air-To-Ground (DA2G) links. These A2G connection types differ in terms of cost, bandwidth, and latency. Furthermore, due to the flights' movements, it is important to consider adapting the service location accordingly. In this work, we formulate two Mixed Integer Linear Programs (MILPs) for the problem of Joint Service Placement and Routing (JSPR): i) Static (S-JSPR), and ii) Mobility-Aware (MA-JSPR) in Space-Air-Ground Integrated networks (SAGIN), with the objective of minimizing the total cost. We compare S-JSPR and MA-JSPR using comprehensive evaluations in a realistic European-based SAGIN. The obtained results show that the MA-JSPR model, by considering the future flight positions and using a service migration control, reduces the long-term total cost notably. Also, we show S-JSPR benefits from a low time-complexity and it achieves lower end-to-end delays comparing to MA-JSPR model. Copyright © 2019, The Authors. All rights reserved.

关键词： Integer programming

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Empirical Predictability Study of SDN Switches

Empirical Predictability Study of SDN Switches

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ACM/IEEE Symposium on Architectures for Networking and communications Systems (ANCS)

作者： Amaury van Bemten Nemanja Ðerić Amir Varasteh Andreas Blenk Stefan Schmid Wolfgang Kellerer Chair of Communication Networks Technical University of Munich Munich Germany Faculty of Computer Science University of Vienna Vienna Austria

To meet their increasingly stringent dependability requirements, communication networks need to be predictable, both in terms of correctness and performance. In principle, Software-Defined networks (SDN) enable such more predictable networks, however, these networks still depend the underlying switches. This paper presents an empirical study of the predictability of SDN switches. Our extensive benchmarking of seven hardware OpenFlow switches from four different manufacturers raises several concerns regarding the dependability of these switches. We uncover several incorrect and unpredictable behaviors and performance issues. In particular, we identify unpredictable behaviors related to the management of flows and buffers, and observe that existing quality-of-service mechanisms, such as priority queuing, introduce unexpected overheads. The latter, in turn, can lead to violations of latency guarantees. Based on our insights, we discuss first solutions toward more predictable architectures.

关键词：

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Discrete-Time Modeling of NFV Accelerators that Exploit Batched Processing

Discrete-Time Modeling of NFV Accelerators that Exploit Batc...

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IEEE Annual Joint Conference: INFOCOM, IEEE computer and communications Societies

作者： Stanislav Lange Leonardo Linguaglossa Stefan Geissler Dario Rossi Thomas Zinner University of Würzburg Institute of Computer Science Chair of Communication Networks Wüurzburg Germany Telecom ParisTech Paris France TU Berlin Berlin Germany

Network Functions Virtualization (NFV) is among the latest network revolutions, bringing flexibility and avoiding network ossification. At the same time, all-software NFV implementations on commodity hardware raise performance issues with respect to ASIC solutions. To address these issues, numerous software acceleration frameworks for packet processing have appeared in the last few years. Common among these frameworks is the use of batching techniques. In this context, packets are processed in groups as opposed to individually, which is required at high-speed to minimize the framework overhead, reduce interrupt pressure, and leverage instruction-level cache hits. Whereas several system implementations have been proposed and experimentally benchmarked, the scientific community has so far only to a limited extent attempted to model the system dynamics of modern NFV routers exploiting batching acceleration. In this paper, we fill this gap by proposing a simple generic model for such batching-based mechanisms, which allows a very detailed prediction of highly relevant performance indicators. These include the distribution of the processed batch size as well as queue size, which can be used to identify loss-less operational regimes or quantify the packet loss probability in high-load scenarios. We contrast the model prediction with experimental results gathered in a high-speed testbed including an NFV router, showing that the model not only correctly captures system performance under simple conditions, but also in more realistic scenarios in which traffic is processed by a mixture of functions.

关键词： Software Computational modeling Predictive models Packet loss System performance Hardware

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Remote Robot Control with Human-in-the-Loop Over Long Distances using Digital Twins

Remote Robot Control with Human-in-the-Loop Over Long Distan...

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IEEE Global communications Conference

作者： Ievgenii A. Tsokalo David Kuss Ievgen Kharabet Frank H. P. Fitzek Martin Reisslein Deutsche Telekom Chair of Communication Networks Technische Universität Dresden Germany Technische Universitat Dresden Dresden Germany Electrical Computer and Energy Eng. Arizona State University Tempe AZ USA

ISBN: (数字)9781728109626

ISBN: (纸本)9781728109633

The sharing of skills over the Internet enables professionals to democratize their expertise and skills without exhausting their availability, e.g., through excessive traveling. To enable this Internet of Skills, we present a novel Digital Twin (DT) platform for the remote control of machines with human-in-the-loop. The DT of a remotely controlled machine acts effectively as an inter-layer between the operator and the controlled machine, e.g., robot arm. The DT can be optimized for a particular application to interact with the operator with an intuitive low-latency interface and, on other side, to control and monitor the quality of the remote task. Essentially, the human operator controls the DT, while the DT controls the remote robot. This paper introduces the DT framework for the remote control. The human-machine-human control loop is split into Virtual Reality (VR), remote control, and robot control loops. The proposed framework achieves low latency visual feedback and very short system reaction times for unexpected changes with arbitrary distances between operator and robot. Within the DT framework, this paper proposes a robot control algorithm for controlling time-critical robot applications over networks with considerable delays and jitter. The proposed framework has been implemented in a demonstrator with a robot arm and its DT in VR.

关键词： Internet Robot control Manipulators Delays Visualization

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Identification of Delay Thresholds Representing the Perceived Quality of Enterprise Applications

Identification of Delay Thresholds Representing the Perceive...

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International Workshop on Quality of Multimedia Experience, QoMEx

作者： Kathrin Borchert Stanislav Lange Thomas Zinner Matthias Hirth Chair of Communication Networks Am Hubland Institute of Computer Science Würzburg Germany

Modern enterprise applications are often designed as distributed architectures, e.g., thin client computing and thus degradations in network related Quality of Service (QoS) parameters may also negatively impact the user-perceived Quality of Experience (QoE) of the application. In this work, we create a model to predict the perceived application quality based on measurements of objective technical parameters. For this, we gathered a data set in a cooperating enterprise over a timespan of nearly three months. As the obtained data set is subject to bias that originates from seasonal effects as well as a limited and predefined set of technical parameters, we further evaluate how to identify segments of the data that lead to misclassification. Last, we quantify the trade-off between the gain in the QoE prediction accuracy and the amount of filtered data.

关键词： Quality of experience Monitoring Tools Quality of service Delays Companies

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SDN Hypervisors: How Much Does Topology Abstraction Matter?

SDN Hypervisors: How Much Does Topology Abstraction Matter?

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International Conference on Network and Service Management

作者： Nemanja Đerić Amir Varasteh Arsany Basta Andreas Blenk Wolfgang Kellerer Chair of Communication Networks Department of Electrical and Computer Engineering Technical University of Munich Germany

ISBN: (纸本)9781538691939;9783903176140

SDN network hypervisors realize the virtualization of software-defined networks. They intercept the control path between tenant controllers and their respective virtual Software-Defined networks (SDN). Over-utilizing SDN hypervisor resources (i.e., CPU) can degrade the control plane performance of the tenants. Although many hypervisor proposals exists, a detailed performance modeling of SDN hypervisors is missing in literature. A precise modeling of the required SDN hypervisor resources, however, is crucial for predictable and reliable operation of virtual software-defined networks. In this paper, we measure and evaluate how topology abstraction can affect the SDN hypervisor CPU utilization. We consider two topology abstraction cases: the (1) transparent and (2) big-switch abstraction. Our measurements taken from a real testbed indicate that the big-switch abstraction can reduce the SDN hypervisor CPU utilization up to $\sim 4\times $. Further, we evaluate different functions to model the SDN hypervisor CPU utilization based on our measurement results. Our evaluations show that a polynomial function provides the lowest fitting error. Motivated by our measurements, we conduct a first-step investigation of the impacts of topology abstraction on the Virtual Network Embedding (VNE) problem. Our initial simulation-based evaluations indicate that different topology abstraction procedures impact the results of the VNE problem.

关键词： Virtual machine monitors Switches Topology Network topology Virtualization Monitoring Estimation

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Performance Evaluation of Mobile Crowdsensing for Event Detection

Performance Evaluation of Mobile Crowdsensing for Event Dete...

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IEEE International Conference on Pervasive Computing and communications

作者： Matthias Hirth Stanislav Lange Michael Seufert Phuoc Tran-Gia University of Würzburg Institute of Computer Science Chair of Communication Networks Würzburg Germany

ISBN: (纸本)9781538632284

Crowdsensing offers a cost effective way to collect large amounts of sensor data. However, in contrast to fixed sensor deployments, the spatial distribution of the sensors can hardly be influence, as the sensors are carried by participants of the crowdsensing system. This in turn raises the question about the performance of such systems with respect to the detection probability and detection time of spatial events. In order to address this question, we analyze the performance of such a crowdsensing system by means of simulation. We use the traffic infrastructure of a small size city in Germany and simulate the inhabitants' movement patterns with the well established SUMO mobility generator. Our results show that even if only a small share of inhabitants participates in crowdsensing, events, which have locations that are correlated with the population density, can be easily and quickly detected using such a system. On the contrary, events whose locations are uniformly randomly distributed are much harder to detect using a crowdsensing approach.

关键词： Sensors Urban areas Sociology Statistics Event detection Performance evaluation Analytical models Event detection Performance Evaluation Sensors Sociology ANALYSIS MODELS urban area TRANSPORT INFRASTRUCTURE inhabitant detection time Sensor Data Population density

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S2V C: An SDN-based framework for maximizing qoe in SVC-based HTTP adaptive streaming

arXiv

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arXiv 2018年

作者： Tashtarian, Farzad Erfanian, Alireza Varasteh, Amir Department of Computer Engineering Mashhad Branch Islamic Azad University Mashhad Iran Chair of Communication Networks Department of Electrical and Computer Engineering Technical University of Munich Germany

HTTP adaptive streaming (HAS) is quickly becoming the dominant video delivery technique for adaptive streaming over the Internet. Still considered as its primary challenges are determining the optimal rate adaptation and improving both the quality of experience (QoE) and QoE-fairness. Most of the proposed approaches have relied on local information to find a result. However, employing techniques that provide a comprehensive and central view of the network resources can lead to more gains in performance. By leveraging software defined networking (SDN), this paper proposes an SDN-based framework, named S 2V C, to maximize QoE metrics and QoE-fairness in SVC-based HTTP adaptive streaming. The proposed framework determines both the optimal adaptation and data paths for delivering the requested video files from HTTP-media servers to DASH clients. In fact, by utilizing an SDN controller and its complete view of the network, we introduce an SVC flow optimizer (SFO) application module to determine the optimal solution in a centralized and time slot fashion. In the current approach, we first formulate the problem as a mixed integer linear programming (MILP) optimization model. The MILP is designed in such a way that it applies defined policies, e.g. setting priorities for clients in obtaining video quality. Secondly, we show that this problem is NP-complete and propose an LP-relaxation model to enable S 2V C framework for performing rate adaptation on a large-scale network. Finally, we conduct experiments by emulating the proposed framework in Mininet, with the usage of Floodlight as the SDN controller. In terms of improving QoE-fairness and QoE metrics, the effectiveness of the proposed framework is validated by a comparison with different approaches. Copyright © 2018, The Authors. All rights reserved.

关键词： Quality of service

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