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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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Greedy design of resilient multi-layer networks

Greedy design of resilient multi-layer networks

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Conference on Next Generation Internet networks, NGI

作者： Michael Duelli Xiaohua Qin Michael Menth Institute of Computer Science Chair of Communication Networks University of Würzburg Wurzburg Germany

ISBN: (纸本)9781424481675

In this paper, we propose a deterministic greedy heuristic providing a construction layout for a cost-efficient multi-layer network that is able to carry a given set of traffic demands with and without protection on different layers. We apply the heuristic to different reference network topologies and protection requirements. Evaluations are conducted regarding equipment cost on different layers, blocking probability, path lengths, and number of demands affected by specific failures.

关键词： Telecommunication traffic Costs Resilience Traffic control Nonhomogeneous media Protection Network topology Optical fiber networks Ethernet networks Spine

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HNLB: Utilizing hardware matching capabilities of NICs for offloading stateful load balancers

arXiv

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arXiv 2019年

作者： Durner, Raphael Varasteh, Amir Stephan, Max MacHuca, Carmen Mas Kellerer, Wolfgang Chair of Communication Networks Department of Electrical and Computer Engineering Technical University of Munich Germany

In order to scale web or other services, the load on single instances of the respective service has to be balanced. Many services are stateful such that packets belonging to the same connection must be delivered to the same instance. This requires stateful load balancers which are mostly implemented in software. On the one hand, modern packet processing frameworks supporting software load balancers, such as the Data Plane Development Kit (DPDK), deliver high performance compared to older approaches. On the other hand, common Network Interface Cards (NICs) provide additional matching capabilities that can be utilized for increasing the performance even further and in turn reduce the necessary server resources. In fact, offloading the packet matching to hardware can free up CPU cycles of the servers. Therefore, in this work, we propose the Hybrid NIC-offloading Load Balancer (HNLB), a high performance hybrid hardwaresoftware load balancer, utilizing the NIC-offloading hardware matching capabilities. The results of our performance evaluations show that the throughput using NIC offloading can be increased by up to 50%, compared to a high performance software-only implementation. Furthermore, we investigated the limitations of our proposed approach, e.g., the limited number of possible concurrent connections. Copyright © 2019, The Authors. All rights reserved.

关键词： Negative impedance converters

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Modeling of crowdsourcing platforms and granularity of work organization in Future Internet

Modeling of crowdsourcing platforms and granularity of work ...

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International Teletraffic Congress, ITC 21

作者： Tobias Hoßfeld Matthias Hirth Phuoc Tran-Gia University of Wurzburg Institute of Computer Science Chair of Communication Networks D-97074 Wurzburg Germany University of Würzburg Chair of Communication Networks Würzburg Germany

Beside of social media networks, crowdsourcing is one of the emerging new applications and business models in the Future Internet, which can dramatically change the future of work and work organization in the on-line world. The crowdsourcing technology can be viewed as "Human Cloud" technique, in contrast to "Machine Cloud Computing". Using a crowd with a large number of internationally widespread workers and the flexibility of micro-payment services, crowdsourcing platforms like Amazon's MTurk and Microworkers can outsource traditional forms of work organization on a microscopic level of granularity to a large, anonymous crowd of workers, the human cloud. In such platforms work or tasks are organized at a finer granularity and jobs are split into micro-tasks that need to be performed by a human cloud. It is a need of analysis to understand the anatomy of such a platform and of models to describe the time-dependent growth of the human cloud, in order to predict the traffic impact of such novel applications and to forecast the growth dynamics. The purpose of this paper is a measurement-based statistical analysis of a crowdsourcing platform, using the *** platform as example. The obtained results are then used to model the growth of such fast-changing environments in the Internet using well-known models from biology. Based on the findings from the population growth, we develop a deterministic fluid model which is an extension of the SIR model of epidemics, in order to investigate the platform dynamics.

关键词： Biological system modeling Humans Logistics Cloud computing Organizations Conferences

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Transmission power control for remote state estimation in industrial wireless sensor networks

arXiv

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arXiv 2019年

作者： Zoppi, Samuele Soleymani, Touraj Klugel, Markus Vilgelm, Mikhail Hirche, Sandra Kellerer, Wolfgang Chair of Communication Networks Department of Electrical and Computer Engineering TUM Germany Chair of Information-Oriented Control Department of Electrical and Computer Engineering TUM Germany

Novel low-power wireless technologies and IoT applications open the door to the Industrial Internet of Things (IIoT). In this new paradigm, Wireless Sensor networks (WSNs) must fulfil, despite energy and transmission power limitations, the challenging communication requirements of advanced manufacturing processes and technologies. In industrial networks, this is possible thanks to the availability of network infrastructure and the presence of a network coordinator that efficiently allocates the available radio resources. In this work, we consider a WSN that simultaneously transmits measurements of Networked Control Systems' (NCSs) dynamics to remote state estimators over a shared packet-erasure channel. We develop a minimum transmission power control (TPC) policy for the coordination of the wireless medium by formulating an infinite horizon Markov decision process (MDP) optimization problem. We compute the policy using an approximate value iteration algorithm and provide an extensive evaluation of its parameters in different interference scenarios and NCSs dynamics. The evaluation results present a comprehensive characterization of the algorithm's performance, proving that it can flexibly adapt to arbitrary use cases. Copyright © 2019, The Authors. All rights reserved.

关键词： Markov processes

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Soft Frequency Reuse in the Uplink of an OFDMA Network

Soft Frequency Reuse in the Uplink of an OFDMA Network

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IEEE Conference on Vehicular Technology (VTC)

作者： Florian Wamser David Mittelstädt Dirk Staehle University of Würzburg Institute of Computer Science Chair of Communication Networks Würzburg Germany

ISBN: (纸本)9781424425181;9781424425198

The challenges with deploying a cellular wireless communication network with static frequency reuse in an interference limited environment is that for highly loaded cells, significant regions of coverage will experience high interference levels, resulting in unserviceable low signal-to-interference values. Therefore, interference mitigation approaches as adaptive fractional frequency reuse are considered to tackle the problem. In this paper, different strategies for user and resource allocation are evaluated along with fractional frequency reuse schemes. In contrast to downlink scenarios, we investigate the performance of the OFDMA uplink. It is shown that soft frequency reuse is well-performing in the uplink although it is easy to deploy since it does not rely on resource coordination.

关键词： Interference Resource management Frequency conversion Radio spectrum management Downlink Mobile computing Throughput Cellular networks computer science communication networks

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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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Analytical Model for the Energy Efficiency in Low Power IoT Deployments

Analytical Model for the Energy Efficiency in Low Power IoT ...

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IEEE Conference on Network Softwarization (NetSoft)

作者： Tobias Hoß feld Simon Raffeck Frank Loh Stefan Geiß ler Chair of Communication Networks University of W&#x00FC rzburg Institute of Computer Science W&#x00FC rzburg Germany

ISBN: (数字)9781665406949

ISBN: (纸本)9781665406956

The recent rise of the Internet of Things (IoT) has given way to numerous challenges and research questions. One of the most critical issues in the area of low powered devices is the question of energy efficiency. Here, technologies like LoRa or Zigbee emerged, promising low power consumption while maintaining adequate performance. However, even when using these tailor made technologies, several configuration aspects need to be taken into account to provide high performance, energy efficient operation. To this end, we propose a generic model to compute the energy efficiency of wireless sensors under the assumption of perfect CSMA/CA channel access. We present numerical results for a typical LoRa device and highlight extensions towards other channel access mechanisms. Finally, we apply Kleinrock’s power metric to obtain ideal system configurations for varying load parameters.

关键词： Performance evaluation Wireless communication Wireless sensor networks Power demand Zigbee Energy efficiency Sensors

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DBM: Decentralized Burst Mitigation for Periodic LoRa Devices Using Self-Organizing Radio Access

DBM: Decentralized Burst Mitigation for Periodic LoRa Device...

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IEEE International Conference on communications (ICC)

作者： Simon Raffeck Stefan Geißler Tobias Hoßfeld Chair of Communication Networks University of Würzburg Institute of Computer Science Würzburg Germany

The steady growth of IoT networks and the rise of LoRa and LoRaWAN as a wireless communication protocol in smart city deployments invoke the need for energy efficient and performance focused channel access mechanisms. Since LoRa makes use of the random access protocol ALOHA, the expected collision probability is directly related to the density of deployed IoT devices. In order to alleviate this scalability issue of LoRa deployments, and the energy losses caused by rising packet collisions, this work proposes a novel channel access mechanism that aims to mitigate high collision probabilities as a result of dense, bursty periods of transmissions, without the need for centralized control instances or dedicated control messages. Based on simulation results, we show that the proposed mechanism is able to mitigate between 30% and 100% of collisions compared to pure ALOHA, depending on factors such as system load and device density.

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Scope of Security Properties of Sanitizable Signatures Revisited

Scope of Security Properties of Sanitizable Signatures Revis...

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International Conference on Availability, Reliability and Security, ARES

作者： Hermann de Meer Henrich C. Pöhls Joachim Posegga Kai Samelin Chair of Computer Communication and Computer Networks University of Passau Passau Germany Universitat Passau Passau Bayern DE Chair of IT-Security University of Passau Passau Germany

Sanitizable signature schemes allow for altering signed data in a signer-controlled way by a semi-trusted third party. This is contrary to standard digital signature schemes, which do not permit any modifications by any party without invalidating the signature. Due to transparency, a strong privacy notion, outsiders cannot see if the signature for a message was created by the signer or by the semi-trusted party. Accountability allows the signer to prove to outsiders if a message was original or touched by the semi-trusted party. Currently, block-level accountability requires to drop transparency. We allow for accountability for sanitizable signatures with transparency on the block-level. Additionally, we generalize the concept of block-level properties to groups. This offers a even more fine-grained control and leads to more efficient schemes. We prove that group-level definitions imply both the block-level and message-level notions. We derive a provably secure construction, achieving our enhanced notions. A further modification of our construction achieves efficient group-level non-interactive public accountability. This construction only requires a constant amount of signature generations to achieve this property. Finally, we have implemented our constructions and the scheme introduced by Brzuska et al. at PKC '09 and provide a detailed performance analysis of our reference implementations.

关键词： Public key Privacy Standards Games Educational institutions Licenses

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