Lidé

Dr. Mgr. Lukáš Kencl

Všechny publikace

HUMAN - Hierarchical Clustering forUnsupervised Anomaly Detection & Interpretation

  • Autoři: Mulinka, P., Casas, P., Kensuke, F., Dr. Mgr. Lukáš Kencl,
  • Publikace: 11th International Conference on Networks of the Future (NoF 2020). St. Paul, Minnesota: IEEE, 2020. p. 132-140. ISBN 978-1-7281-8055-7.
  • Rok: 2020
  • DOI: 10.1109/NoF50125.2020.9249194
  • Odkaz: https://doi.org/10.1109/NoF50125.2020.9249194
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    The automatic detection and interpretation of network traffic anomalies through machine learning is a well-known problem, for which no general solution is available. Both supervised and unsupervised (i.e., anomaly detection) approaches require prior knowledge on the monitoring data, either in terms of normal operation profiles or on the specific anomalies to detect. As a consequence, both approaches have clear limitations when it comes to detecting, and in particular interpreting, previously unseen events. We present HUMAN, a general hierarchical-clustering-based approach for unsupervised network traffic analysis, which can both detect and interpret anomalous behaviors ina completely black-box manner, without relying on any ground-truth on the system under analysis. HUMAN can detect and interpret complex patterns in the analyzed data, using a structural approach which exploits hierarchical cluster relationships and correlations among features. We describe the building blocks of HUMAN and explain its functioning in detail, using as case study the detection and interpretation of performance issues in major cloud platforms, through the unsupervised analysis of distributed active cloud latency measurements. The HUMAN approach can be applied to the unsupervised analysis of any kind of nested or hierarchically structured multi-dimensional data, showing the potential of hierarchical clustering for general unsupervised data analytics.

WhatsThat? On the Usage of Hierarchical Clustering for Unsupervised Detection & Interpretation of Network Attacks

  • Autoři: Mulinka, P., Fukuda, K., Casas, P., Dr. Mgr. Lukáš Kencl,
  • Publikace: 2020 IEEE European Symposium on Security and Privacy Workshops (EuroS&PW). Piscataway (New Jersey): IEEE, 2020. p. 574-583. ISBN 978-1-7281-8597-2.
  • Rok: 2020
  • DOI: 10.1109/EuroSPW51379.2020.00084
  • Odkaz: https://doi.org/10.1109/EuroSPW51379.2020.00084
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    The automatic detection and interpretation of network attacks through machine learning is a well-known problem, for which no general solution is available. Supervised learning and anomaly detection approaches require prior knowledge about the system under analysis, either in terms of normal operation profiles or on the specific attacks to detect. As a consequence, both approaches have clear limitations when it comes to detecting, and in particular interpreting, previously unseen attacks and anomalies. In this paper we present WhatsThat, a novel approach to unsupervised network anomaly detection, which can both detect and interpret anomalous behaviors in a completely black-box manner, without relying on any ground-truth on the system under analysis. WhatsThat relies on hierarchical clustering techniques to discover and characterize anomalous patterns present in nested or hierarchically structured multidimensional data, which is common in network traffic e.g., due to multi-layer protocols. The solution uses unsupervised cluster validity metrics to automatically explore the data structure, and builds on automatic identification of relevant features to provide meaningful descriptions of the detected patterns. We showcase WhatsThat in the detection and interpretation of network attacks hidden in real, large-scale network traffic collected at a transit Internet backbone network. While WhatsThat is mainly tailored for unsupervised anomaly detection and interpretation, it can also be applied to the unsupervised analysis of any kind of nested or hierarchically structured multi-dimensional data, showing the potential of hierarchical clustering for general unsupervised data analytics.

Enhanced Secure Thresholded Data Deduplication Scheme for Cloud Storage

  • Autoři: Staněk, J., Dr. Mgr. Lukáš Kencl,
  • Publikace: IEEE Transactions on Dependable and Secure Computing. 2018,(99), 694-707. ISSN 1545-5971.
  • Rok: 2018
  • DOI: 10.1109/TDSC.2016.2603501
  • Odkaz: https://doi.org/10.1109/TDSC.2016.2603501
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    As more corporate and private users outsource their data to cloud storage, recent data breach incidents make end-to-end encryption increasingly desirable. Unfortunately, semantically secure encryption renders various cost-effective storage optimization techniques, such as data deduplication, ineffective. On this ground Stanek et al. [1] introduced the concept of “data popularity” arguing that data known/owned by many users do not require as strong protection as unpopular data; based on this, Stanek et al. presented an encryption scheme, where the initially semantically secure ciphertext of a file is transparently downgraded to a convergent ciphertext that allows for deduplication as soon as the file becomes popular. In this paper we propose an enhanced version of the original scheme. Focusing on practicality, we modify the original scheme to improve its efficiency and emphasize clear functionality. We analyze the efficiency based on popularity properties of real datasets and provide a detailed performance evaluation, including comparison to alternative schemes in real-like settings. Importantly, the new scheme moves the handling of sensitive decryption shares and popularity state information out of the cloud storage, allowing for improved security notion, simpler security proofs and easier adoption. We show that the new scheme is secure under the Symmetric External Diffie-Hellman assumption in the random oracle model.

Hi-Clust: Unsupervised Analysis of Cloud Latency Measurements Through Hierarchical Clustering

  • Autoři: Mulinka, P., Casas, P., Dr. Mgr. Lukáš Kencl,
  • Publikace: Proceedings of the 2018 IEEE 7th International Conference on Cloud Networking (CloudNet). Piscataway: IEEE, 2018. p. 1-7. ISBN 978-1-5386-6831-3.
  • Rok: 2018
  • DOI: 10.1109/CloudNet.2018.8549558
  • Odkaz: https://doi.org/10.1109/CloudNet.2018.8549558
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Latency is nowadays one of the most relevant network and service performance metrics reflecting end-user experience. With the wide adoption and deployment of delay-sensitive applications in the Cloud (e.g., gaming, interactive video conferencing, corporate services, etc.), monitoring and analysis of Cloud service latency is becoming increasingly relevant for Cloud service providers, tenants and even users. Traditional network monitoring approaches based on time-series analysis and thresholding are capable of raising alarms when anomalous events arise, but are not applicable to detect correlations among multiple monitored dimensions, necessary to provide an adequate interpretation of an anomaly. In this paper we present Hi-Clust, an unsupervised-based approach for analyzing and interpreting anomalies in multi-dimensional network data, through the application of hierarchical clustering techniques. While Hi-Clust is applicable to the analysis of different types of nested or hierarchically structured data, we particularly focus on the analysis of Cloud service latency, using active measurements collected from geographically distributed vantage points. We implement and benchmark multiple density-based clustering approaches for Hi-Clust over four weeks of real multidimensional Cloud service latency measurements. Using the most robust underlying clustering algorithm from the benchmark, we show how to automatically extract and interpret anomalous Cloud service behavior with Hi-Clust. In addition, we show the advantages of Hi-Clust over traditional threshold-based approaches for detecting and interpreting anomalous behavior, through practical examples over the collected measurements.

Optimization of Cloud Connectivity using a Smart-home Gateway

  • Autoři: Tománek, O., Dr. Mgr. Lukáš Kencl,
  • Publikace: ICC 2018. Piscataway, NJ: IEEE, 2018. ISSN 1550-3607. ISBN 9781538631805.
  • Rok: 2018
  • DOI: 10.1109/ICC.2018.8422768
  • Odkaz: https://doi.org/10.1109/ICC.2018.8422768
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    When consuming Cloud services from their homes, contemporary users face a significant degree of uncertainty with regards to Cloud–service performance and reliability. This uncertainty could be addressed by an intelligent approach deployed within a smart home gateway, which would continuously reevaluate and reassign Cloud–bound traffic to a momentarily optimal destination. We demonstrate that such optimization could bring significant benefits to individual users in terms of quality and reliability of the provided Cloud service. Furthermore, we sketch a schema of a methodology that regularly reassigns Cloud– bound traffic, based on past measurements and a constrained optimization computation; we present an experimental performance evaluation of such approach and discuss feasibility of its implementation.

VeraGreg: A Framework for Verifiable Privacy-Preserving Data Aggregation

  • Autoři: Klemsa, J., Dr. Mgr. Lukáš Kencl, Ing. Tomáš Vaněk, Ph.D.,
  • Publikace: 2018 17th IEEE International Conference On Trust, Security And Privacy In Computing And Communications/ 12th IEEE International Conference On Big Data Science And Engineering (TrustCom/BigDataSE). IEEE, 2018. p. 1820-1825. ISSN 2324-9013. ISBN 978-1-5386-4387-7.
  • Rok: 2018
  • DOI: 10.1109/TrustCom/BigDataSE.2018.00275
  • Odkaz: https://doi.org/10.1109/TrustCom/BigDataSE.2018.00275
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    A lot of effort has been made to devise a scheme for verifiable and privacy-preserving outsourcing of arbitrary computations. However, such schemes rely on Fully Homomorphic Encryption which is still far from practical. In our work, we instead focus solely on encryption schemes with single homomorphic operation, in particular addition. We define a rigorous framework that gives the data originator a possibility to check what values have been incorporated within provided homomorphic aggregate. We also propose a practical scheme that instantiates this framework and prove that it achieves Indistinguishability under Non-Adaptive Chosen Ciphertext Attack (IND-CCA1). The definition of our framework led us further to a straightforward modification of the security notions of Non-Malleability (NM) and Adaptive Chosen Ciphertext Attack (CCA2). Our modification aims at preventing trivial breach which is by principle unavoidable for plain homomorphic encryption. With our enhancement, the notions of security can serve as a novel security goal for any future verifiable homomorphic schemes.

Evaluation of Datacenter Network Topology Influence on Hadoop MapReduce Performance

  • Autoři: Kouba, Z., Tománek, O., Dr. Mgr. Lukáš Kencl,
  • Publikace: 5th IEEE International Conference on Cloud Networking (Cloudnet). Piscataway: IEEE, 2016. p. 95-100. ISBN 978-1-5090-5093-2.
  • Rok: 2016
  • DOI: 10.1109/CloudNet.2016.19
  • Odkaz: https://doi.org/10.1109/CloudNet.2016.19
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Hadoop MapReduce has nowadays become the de-facto standard for the Big-Data processing within Cloud datacenters. However, little is known about the influence of datacenter network topology on Hadoop performance, and suitability of various topologies for different workload distributions. By extending a publicly available simulator CloudSim, we simulate six well-known or recently proposed topologies (Hierarchical, FatTree, DCell, CamCube, BCube, MapReduce) and evaluate Hadoop MapReduce performance across varyingly distributed workloads. We conclude that while no topology is clearly optimal, the experimental CamCube topology exhibits the most promising results. However, different topologies correspond to different workload divisions in terms of best performance, with greatly differing results, and generally weak performance under highly skewed workloads. This finding could lead to significant Hadoop MapReduce performance improvements by adjusting or selecting appropriate datacenter network topologies – potentially even at runtime, using Software Defined Networking.

Latency-based Benchmarking of Cloud Service Providers

  • Autoři: Uhlíř, V., Tománek, O., Dr. Mgr. Lukáš Kencl,
  • Publikace: UCC '16 Proceedings of the 9th International Conference on Utility and Cloud Computing. New York: ACM, 2016. p. 263-268. ISSN 2373-6860. ISBN 978-1-4503-4616-0.
  • Rok: 2016
  • DOI: 10.1145/2996890.3007870
  • Odkaz: https://doi.org/10.1145/2996890.3007870
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    With the ever-increasing trend of migration of applications to the Cloud environment, there is a growing need to thoroughly evaluate quality of the Cloud service itself, before deciding upon a hosting provider. Benchmarking the Cloud services is difficult though, due to the complex nature of the Cloud Computing setup and the diversity of locations, of applications and of their specific service requirements. However, such comparison may be crucial for decision making and for troubleshooting of services offered by the intermediate businesses - the so-called Cloud tenants. Existing cross-sectional studies and benchmarking methodologies provide only a shallow comparison of Cloud services, whereas state-of-the-art tooling for specific comparisons of application-performance parameters, such as for example latency, is insufficient. In this work, we propose a novel methodology for benchmarking of Cloud-service providers, which is based on latency measurements collected via active probing, and can be tailored to specific application needs. Furthermore, we demonstrate its applicability on a practical longitudinal study of real measurements of two major Cloud-service providers - Amazon and Microsoft.

Multidimensional Cloud Latency Monitoring and Evaluation

  • Autoři: Tománek, O., Mulinka, P., Dr. Mgr. Lukáš Kencl,
  • Publikace: Computer Networks. 2016, 107(1), 104-120. ISSN 1389-1286.
  • Rok: 2016
  • DOI: 10.1016/j.comnet.2016.06.011
  • Odkaz: https://doi.org/10.1016/j.comnet.2016.06.011
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Measuring or evaluating performance of a Cloud service is a non-trivial and highly ambiguous task. We focus on Cloud-service latency from the user’s point of view, and, to this end, utilize the multidimensional latency measurements obtained using an in-house designed active-probing platform, CLAudit, deployed across PlanetLab and Microsoft Azure datacenters. The multiple geographic Vantage Points, multiple protocol layers and multiple datacenter locations of CLAudit measurements allow us to pinpoint with great precision if, where and what kind of a particular latency-generating event has happened. We analyze and interpret measurements over two one-month time-intervals, one in 2013 and one in 2016. As these traces are large, an automated interpretation has been appended to the data-capture process. In summary, we demonstrate the utility of the multidimensional approach and document the differences in the measured Cloud-services latency over time. Our measurements data is publicly available and we encourage the research community to use it for verification and further studies.

Security and Privacy of Using AllJoyn IoT Framework at Home and Beyond

  • Autoři: Tománek, O., Dr. Mgr. Lukáš Kencl,
  • Publikace: The Proceedings of the 2nd International Conference on Intelligent Green Building and Smart Grid (IGBSG). Praha: IEEE Czechoslovakia Section, 2016. p. 18-23. ISBN 978-1-4673-8473-5.
  • Rok: 2016
  • DOI: 10.1109/IGBSG.2016.7539413
  • Odkaz: https://doi.org/10.1109/IGBSG.2016.7539413
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    AllJoyn is one of the emerging standards for the upcoming revolution known as Internet of Things. Within a couple of years, many devices and appliances in every home are expected to be interconnected, and connected to the global network, using this standard defined by the AllSeen Alliance. In this work, we first review the current status and architecture of the AllJoyn open standard, with special focus on its security aspects. Then, we discuss the security and privacy of the imminent deployment of AllJoyn within homes, buildings and urban infrastructures across the globe, documenting the need for strong consideration of remedies to the listed vulnerabilities.

Learning from Cloud Latency Measurements

  • Autoři: Mulinka, P., Dr. Mgr. Lukáš Kencl,
  • Publikace: 2015 IEEE International Conference on Communication Workshop. Pomona, California: IEEE Communications Society, 2015. p. 1895-1901. ISBN 978-1-4673-6305-1.
  • Rok: 2015
  • DOI: 10.1109/ICCW.2015.7247457
  • Odkaz: https://doi.org/10.1109/ICCW.2015.7247457
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Measuring, understanding, troubleshooting and optimizing various aspects of a Cloud Service hosted in remote datacenters is a vital, but non-trivial task. Carefully arranged and analyzed periodic measurements of Cloud-Service latency can provide strong insights into the service performance. A Cloud Service may exhibit latency and jitter which may be a compound result of various components of the remote computation and intermediate communication. We present methods for automated detection and interpretation of suspicious events within the multidimensional latency time series obtained by CLAudit, the previously presented planetary-scale Cloud-Service evaluation tool. We validate these methods of unsupervised learning and analyze the most frequent Cloud-Service performance degradations.

Revealing Viber Communication Patterns to Assess Protocol Vulnerability

  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Viber is a proprietary communication protocol growing in popularity, on mobile devices especially. It represents a trend of replacing traditional protocols with proprietary messaging applications, employing cloud infrastructure support. It also constitutes a challenge to the networking community due to its unknown properties and opaque and highly distributed nature. We present observations-based analysis of the protocol function, topology, communication patterns and vulnerabilities, derived from traffic captures by simple data mining.

A Secure Data Deduplication Scheme for Cloud Storage

  • Autoři: Staněk, J., Dr. Mgr. Lukáš Kencl, Sorniotti, A., Androulaki, E.
  • Publikace: Proceedings of the 18th Financial Cryptography and Data Security conference 2014. Berlin: Springer, 2014. p. 99-118. Lecture Notes in Computer Science. ISSN 0302-9743. ISBN 978-3-662-45471-8.
  • Rok: 2014
  • DOI: 10.1007/978-3-662-45472-5_8
  • Odkaz: https://doi.org/10.1007/978-3-662-45472-5_8
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    As more corporate and private users outsource their data to cloud storage providers, recent data breach incidents make end-to-end encryption an increasingly prominent requirement. Unfortunately, semantically secure encryption schemes render various cost-e ective stor- age optimization techniques, such as data deduplication, ine ective. We present a novel idea that di erentiates data according to their popular- ity. Based on this idea, we design an encryption scheme that guarantees semantic security for unpopular data and provides weaker security and better storage and bandwidth bene ts for popular data. This way, data deduplication can be e ective for popular data, whilst semantically secure encryption protects unpopular content. We show that our scheme is secure under the Symmetric External Decisional Diffie-Hellman Assumption in the random oracle model.

Analyzing anomalies in anonymized SIP traffic

  • Autoři: Staněk, J., Dr. Mgr. Lukáš Kencl, Kuthan, J.
  • Publikace: 2014 IFIP Networking Conference, Proceedings. Piscataway: IEEE, 2014, pp. 1-9. ISBN 9783901882586. Available from: http://80.ieeexplore.ieee.org.dialog.cvut.cz/xpl/articleDetails.jsp?tp=&arnumber=6857106
  • Rok: 2014
  • DOI: 10.1109/IFIPNetworking.2014.6857106
  • Odkaz: https://doi.org/10.1109/IFIPNetworking.2014.6857106
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    The Session Initiation Protocol (SIP) is a signaling protocol widely used nowadays for controlling multimedia communication sessions. Thus, understanding and troubleshooting SIP behavior is of utmost importance to network designers and operators. However, SIP traffic traces are hard to come by due to privacy and confidentiality issues. SIP contains a lot of personal information spread within the various SIP messages - IP addresses, names, usernames and domains, e-mail addresses etc. The known IP-address anonymization methods are thus insufficient. We present SiAnTo, an extended anonymization technique that substitutes session-participant information with matching, but nondescript, labels. This allows for SIP traces to be publicly shared, while keeping interesting traffic-session properties intact. We further demonstrate its usefulness by studying the problem of SIP NAT traversal as recorded in the anonymized traces. We analyze properties of the so-called “registration storm” incident and measure the influence of the active NAT traversal techniques on SIP traffic pattern, both only possible thanks to the preservation of session relationships inside the anonymized traces. As further benefit to the research community, we set up a public data-store with both the anonymization module and the anonymized traces available and invite other parties to share further SIP data using these open tools.

Stateless generation of distributed virtual worlds

  • DOI: 10.1016/j.cag.2014.07.002
  • Odkaz: https://doi.org/10.1016/j.cag.2014.07.002
  • Pracoviště: Katedra telekomunikační techniky, Katedra počítačové grafiky a interakce
  • Anotace:
    We present novel techniques for implementing possibly infinite on-demand generated 3D virtual worlds in distributed environments. Our approach can be useful in two scenarios: 1. A multiuser virtual world with mobile clients with sufficient CPU and GPU power but with limited network speed. This reflects current mobile phones, tablets and laptops in areas without a high-speed mobile connection or Wi-Fi connectivity. 2. Virtual world on-demand generation in a cloud environment that would be useful for scalable massive multiplayer games. If multiple independent generators create areas that are overlapping, our method ensures that the intersection of the areas will contain the same geometry for all of them. For this reason, we call our method stateless generation.

Active Tracking in Mobile Networks: An in-depth View

  • Autoři: Ficek, M., Pop, T., Dr. Mgr. Lukáš Kencl,
  • Publikace: Computer Networks. 2013, 57(9), 1936-1954. ISSN 1389-1286.
  • Rok: 2013
  • DOI: 10.1016/j.comnet.2013.03.013
  • Odkaz: https://doi.org/10.1016/j.comnet.2013.03.013
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Tracking of mobile terminals in mobile networks is a technology with growing and diverse applicability. However, this task is non-trivial and might require either terminal or network adjustment and cooperation. Flexible, scalable, and cost-effective means of network-based tracking are highly desirable from the perspective of mobile operators. We present an in-depth overview of a particular method, the SMS-based active tracking, and demonstrate how this lean and non-intrusive approach is applicable to various existing architectures of mobile networks. We show the practicality of this approach by describing our academic proof-of-concept implementation, capable of tracking thousands of users periodically on the scale of minutes. We analyze the limits of active tracking, posed by the various network and terminal constraints (such as connection throughput, mobile network capacity or terminal battery lifetime) and conclude with discussion of its wide and long-term applicability.

Characteristics of Real Open SIP-Server Traffic

  • Autoři: Staněk, J., Kuthan, J., Dr. Mgr. Lukáš Kencl,
  • Publikace: Proceedings, 14th International Conference on Passive and Active Measurement, PAM 2013. Berlin: Springer, 2013, pp. 187-197. Lecture Notes in Computer Science. ISSN 0302-9743. ISBN 978-3-642-36515-7. Available from: http://link.springer.com/chapter/10.1007%2F978-3-642-36516-4_19
  • Rok: 2013
  • DOI: 10.1007/978-3-642-36516-4_19
  • Odkaz: https://doi.org/10.1007/978-3-642-36516-4_19
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Voice-over-IP (VoIP) is currently one of the most commonly used communication options and Session Initiation Protocol (SIP) is most often used for VoIP deployment. However, there is not a lot of general knowledge about typical SIP traffic and behavior and research work in this area largely works with various assumptions. To address this deficiency, we present a thorough study of traffic of a real, free and publicly open SIP server. The findings reveal, among others, a surprisingly high overhead of SIP due to connection maintenance through NAT nodes, differences from typical HTTP Power-law patterns and various unexpected creative uses of SIP servers for commercial services. We also discuss the (un)suitability of SIP deployment into a cloud environment.

CLAudit: Planetary-scale Cloud Latency Auditing Platform

  • Autoři: Tománek, O., Dr. Mgr. Lukáš Kencl,
  • Publikace: Proceedings of the 2013 IEEE 2nd International Conference on Cloud Networking (CloudNet). Piscataway: IEEE, 2013. p. 138-146. ISBN 978-1-4799-0566-9.
  • Rok: 2013
  • DOI: 10.1109/CloudNet.2013.6710568
  • Odkaz: https://doi.org/10.1109/CloudNet.2013.6710568
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Latency is an important, yet often underestimated aspect of the nascent Cloud-Computing scenario. A cloud service based on processing in remote datacenters may exhibit latency and jitter which may be a compound result of many various components of the remote computation and intermediate communication. Our broad vision is to design and develop tools to monitor, model and optimize the global cloud-service latency. To this end, we introduce CLAudit, a prototype planetary-scale cloud-latency auditing platform. It utilizes the experimental PlanetLab network to place globally distributed probes that periodically measure cloud-service latency at various layers of the communication stack. We present CLAudit architecture in detail and show initial test-measurements of the MicrosoftWindows Azure cloud service, demonstrating the platform's practical usefulness by showcasing a few discovered anomalous results in the cloud-service latency measurements.

Collaborative 3D Environments over Windows Azure

  • Autoři: Danihelka, J., Dr. Mgr. Lukáš Kencl,
  • Publikace: Service Oriented System Engineering (SOSE), 2013 IEEE 7th International Symposium on Mobile Cloud , Computing, and Service Engineering. New York: IEEE Computer Society Press, 2013. p. 472-477. ISBN 978-0-7695-4944-6.
  • Rok: 2013
  • DOI: 10.1109/SOSE.2013.41
  • Odkaz: https://doi.org/10.1109/SOSE.2013.41
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Microsoft Windows Azure and other cloud platforms are potentially well suited for building and deploying rapidly scalable 3D environments, usable for multi-player online games or interactive 3D education and e-commerce. Such 3D environments need to allow cooperation and interaction of multiple users in a single world. This may be difficult to synchronize due to network and cloud-operation delays. We present the project on building 3D services in the cloud, an example implementation of such an application, a shared 3D Teapot in Windows Azure, and a measurements-based discussion of performance issues when the teapot is shared and actively manipulated by many simultaneous users.

Mobility Data Anonymization by Obfuscating the Cellular Network Topology Graph

  • Autoři: Baena Martínez, E., Ficek, M., Dr. Mgr. Lukáš Kencl,
  • Publikace: Proceedings of the 2013 IEEE International Conference on Communications (ICC). Piscataway: IEEE, 2013. pp. 2032-2036. IEEE International Conference on Communications. ISSN 1550-3607. ISBN 978-1-4673-3122-7.
  • Rok: 2013
  • DOI: 10.1109/ICC.2013.6654824
  • Odkaz: https://doi.org/10.1109/ICC.2013.6654824
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Studies of cellular-network data, comprising analyses of user movements across the network, are becoming increasingly popular with the rise of new services based on user behavior and geographic location. Such data might contain, for example, timestamped lists of IDs of cells a user was registered to. If coupled with the cell locations, confidential to the operator, this would enable reconstruction of user trajectories across the regions covered. It is vital to preserve privacy of this data for all parts involved (users, operators) while enabling open sharing of the data to foster research and development of new findings, services and technologies based on mining of this data. Thus, we pose the problem of obfuscating entire cellular-network topologies while retaining some of the analytical value of the user data. To this end, we adopt multiple obfuscation methods based on different topology-graph distortions, and analyze their performance using simulated scenarios.

3D Talking-Head Interface to Voice-Interactive Services on Mobile Phones

  • Autoři: Danihelka, J., Dr. Mgr. Lukáš Kencl, Hák, R., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Developments in Technologies for Human-Centric Mobile Computing and Applications. Hershey, Pennsylvania: IGI Global, 2012. p. 130-144. ISBN 9781466620681.
  • Rok: 2012
  • DOI: 10.4018/978-1-4666-2068-1.ch008
  • Odkaz: https://doi.org/10.4018/978-1-4666-2068-1.ch008
  • Pracoviště: Katedra telekomunikační techniky, Katedra počítačové grafiky a interakce
  • Anotace:
    This paper presents a novel framework for easy creation of interactive, platform-independent voice-services with an animated 3D talking-head interface, on mobile phones. The Framework supports automated multi-modal interaction using speech and 3D graphics. The difficulty of synchronizing the audio stream to the animation is examined and alternatives for distributed network control of the animation and application logic is discussed. The ability of modern mobile devices to handle such applications is documented and it is shown that the power consumption trade-off of rendering on the mobile phone versus streaming from the server favors the phone. The presented tools will empower developers and researchers in future research and usability studies in the area of mobile talking-head applications (Figure 1). These may be used for example in entertainment, commerce, health care or education.

Can Crowdsensing Beat Dynamic Cell-ID?

  • Autoři: Ficek, M., Clark, N., Dr. Mgr. Lukáš Kencl,
  • Publikace: Proceedings of the Third International Workshop on Sensing Applications on Mobile Phones. New York: ACM, 2012. pp. 1-5. ISBN 978-1-4503-1778-8.
  • Rok: 2012
  • DOI: 10.1145/2389148.2389158
  • Odkaz: https://doi.org/10.1145/2389148.2389158
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    In this work we investigate the limits of crowdsensing in discovering the mapping of mobile network Cell-IDs to geographic locations. We employ original large-scale mobility simulations, derived using the NRC-Lausanne dataset, to determine the fraction of cells visited by a fixed number of users over a time interval. This is vital to judge the ability of crowdsensing to rapidly update an inadequate, malfunctioning or obsolete Cell-ID database, thus preventing mechanisms such as Dynamic Cell-ID from obfuscating the network. We show that crowdsensing is quite a powerful tool, with for example only 25% more users than cells sufficing to scan 99% of the network over a day.

Cloud-based Assistive Speech-Transcription Services

  • Autoři: Bumbálek, Z., Zelenka, J., Dr. Mgr. Lukáš Kencl,
  • Publikace: Computers Helping People with Special Needs. Heidelberg: Springer, 2012. p. 113-116. Lecture Notes in Computer Science. ISSN 0302-9743. ISBN 978-3-642-31521-3.
  • Rok: 2012
  • DOI: 10.1007/978-3-642-31534-3_17
  • Odkaz: https://doi.org/10.1007/978-3-642-31534-3_17
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Real-time speech transcription is a service of potentially tre- mendous positive impact on quality of life of the hearing-impaired. Recent advances in technologies of mobile networks, cloud services, speech transcription and mobile clients allowed us to build eScribe, a ubiquitiously available, cloud-based, speech-transcription service. We present the deployed system, evaluate the applicability of automated speech recognition using real measurements and outline a vision of the future enhanced platform, crowdsourcing human transcribers in social networks.

Improving QoE of SIP-based Automated Voice Interaction in Mobile Networks

  • Autoři: Doležal, J., Dr. Mgr. Lukáš Kencl,
  • Publikace: Proceedings of the 8th International Conference on Network and Service Management (CNSM 2012). Piscataway: IEEE, 2012. pp. 329-335. ISBN 978-3-901882-48-7.
  • Rok: 2012
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Mobile voice-assisted services are currently experiencing strong growth. However, occasionally low real-time quality of service within mobile networks could have significant negative impact on quality of experience of users interacting with automated voice services. Latency may grow to unacceptable levels and speech recognition and synthesis might suffer. We present a methodology of mitigating such effects by monitoring the immediate connection status and adapting various parameters of the SIP communication setup (buffer size, codec) in response, thus radically improving user experience. We demonstrate practical usability by implementation and testing in a real mobile network and by performing multiple test scenarios when interacting with a state-of-the-art automated voice platform.

Inter-Call Mobility Model: A Spatio-temporal Refinement of Call Data Records Using a Gaussian Mixture Model

  • Autoři: Ficek, M., Dr. Mgr. Lukáš Kencl,
  • Publikace: 2012 Proceedings IEEE INFOCOM. Piscataway: IEEE, 2012. p. 469-477. ISSN 0743-166X. ISBN 978-1-4673-0774-1.
  • Rok: 2012
  • DOI: 10.1109/INFCOM.2012.6195786
  • Odkaz: https://doi.org/10.1109/INFCOM.2012.6195786
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    With global mobile phone penetration nearing 100%, cellular Call Data Records (CDRs) provide a large-scale and ubiquitous, but also sparse and skewed snapshot of human mobility. It may be difficult or inappropriate to reach strong conclusions about user movement based on such data without proper understanding of user movement between call records. Based on an analysis of a real-world trace, we propose a novel, probabilistic Inter-Call Mobility (ICM) model of users' position in between calls. The ICM model combines Gaussian mixtures to build a general, comprehensive spatio-temporal refinement of CDRs. We demonstrate that ICM model's application yields strik-ingly different conclusions to the existing models when applied to basic CDR analyses, such as user proximity probability.

SIP Protector: Defense Architecture Mitigating DDoS Flood Attacks Against SIP Servers

  • Autoři: Staněk, J., Dr. Mgr. Lukáš Kencl,
  • Publikace: Proceedings of the 2012 IEEE International Conference on Communications (ICC 2012). Piscataway: IEEE, 2012. pp. 6733-6738. ISSN 1550-3607. ISBN 978-1-4577-2053-6.
  • Rok: 2012
  • DOI: 10.1109/ICC.2012.6364674
  • Odkaz: https://doi.org/10.1109/ICC.2012.6364674
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    As Voice-over-IP becomes a commonly used technology, the need to keep it secure and reliable has grown. Session Initiation Protocol (SIP) is most often used to deploy VoIP and therefore SIP servers, the base components of SIP, are the most obvious targets of potential attacks. It has been demonstrated, that SIP servers are highly prone to DDoS flood attacks, yet no generally accepted defense solution mitigating these attacks is available. We propose a novel defense architecture against SIP DDoS floods, based upon a redirection mechanism and a combination of source and destination traffic filtering, exploiting the combined advantage of all the three techniques. We show that the proposed solution effectively mitigates various types of SIP DDoS flood attacks, discuss its strengths and weaknesses and propose its potential usability for other protocols. We also provide results of performance evaluation of the defense solution deployed in a SIP testbed.

3D Talking-Head Interface to Voice-Interactive Services on Mobile Phones

  • DOI: 10.4018/jmhci.2011040104
  • Odkaz: https://doi.org/10.4018/jmhci.2011040104
  • Pracoviště: Katedra telekomunikační techniky, Katedra počítačové grafiky a interakce
  • Anotace:
    This paper presents a novel framework for easy creation of interactive, platform-independent voice-services with an animated 3D talking-head interface, on mobile phones. The Framework supports automated multi-modal interaction using speech and 3D graphics. The difficulty of synchronizing the audio stream to the animation is examined and alternatives for distributed network control of the animation and application logic is discussed. The ability of modern mobile devices to handle such applications is documented and it is shown that the power consumption trade-off of rendering on the mobile phone versus streaming from the server favors the phone. The presented tools will empower developers and researchers in future research and usability studies in the area of mobile talking-head applications (Figure 1). These may be used for example in entertainment, commerce, health care or education.

A Unifying Architecture for Easy Development, Deployment and Management of Voice-Driven Mobile Applications

  • Autoři: Doležal, J., Dr. Mgr. Lukáš Kencl,
  • Publikace: 2011 7th International Conference on Network and Service Management (CNSM 2011). Piscataway: IEEE, 2011. pp. 1-5. ISBN 978-1-4577-1588-4.
  • Rok: 2011
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    With the advances in voice recognition and synthesis, voice-interactive applications are reaching the mass mobile market. However, creating, deploying or managing context-rich voice-driven applications is complicated due to the scattered and highly diverse nature of specific pieces of software, tools and skills required for a complete system solution. To overcome this, we propose a novel unifying architecture for easy development, deployment and management of voice driven applications which seamlessly integrates mobility and context-awareness, user- and dialog-management, multi-modal interaction and continuous performance measurement and evaluation. Finally, we validate the architecture by stress tests examining possible bottlenecks.

Adaptive Load Balancing for the Agile All-Photonic Network

  • Autoři: Khazali, I., Agarwal, A., Dr. Mgr. Lukáš Kencl,
  • Publikace: Proceedings Ninth Annual Communication Networks and Services Research Conference CNSR 2011. Los Alamitos: IEEE Computer Society, 2011. pp. 181-188. ISBN 978-0-7695-4393-2.
  • Rok: 2011
  • DOI: 10.1109/CNSR.2011.34
  • Odkaz: https://doi.org/10.1109/CNSR.2011.34
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    A novel routing architecture that balances incoming traffic over the Agile All-Photonic Network (AAPN) is proposed. The architecture is based on the adaptive highest random weight (Adaptive HRW) algorithm proposed to design load balanced internet routers. It extends the adaptive HRW algorithm by assigning balancing weights to each source-destination edge node pair in the network. The weights are adapted based on the traffic load of the downstream and upstream links in the network. The architecture can be seen as a combination of adaptive core node scheduling and adaptive load balancing at the edge nodes. It is stateless and can compute routes quickly based on the packet flow identifier. This is an important issue when deploying AAPN as an internet backbone network where the number of flows is large and storing flow state in lookup tables can limit the network performance.

Energy Consumption Comparison Between Macro-Micro and Public Femto Deployment in a Plausible LTE Network

  • Autoři: Dufková, K., Le Boudec, J-Y., Popović, M., Bjelica, M., Khalili, R., Dr. Mgr. Lukáš Kencl,
  • Publikace: Proceedings of the 2nd International Conference on Energy-Efficient Computing and Networking. New York: ACM, 2011. pp. 67-76. ISBN 978-1-4503-1313-1.
  • Rok: 2011
  • DOI: 10.1145/2318716.2318730
  • Odkaz: https://doi.org/10.1145/2318716.2318730
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    We study the energy consumptions of two strategies that increase the capacity of an LTE network: (1) the deployment of redundant macro and micro base stations by the operator at locations where the traffic is high, and (2) the deployment of publicly accessible femto base stations by home users. Previous studies show the deployment of publicly accessible residential femto base stations is considerably more energy efficient; however, the results are proposed using an abstracted model of LTE networks, where the coverage constraint was neglected in the study, as well as some other important physical and traffic layer specifications of LTE networks. We study a realistic scenario where coverage is provided by a set of non-redundant macro-micro base stations and additional capacity is provided by redundant macro-micro base stations or by femto base stations. We quantify the energy consumption of macro-micro and femto deployment strategies by using a simulation of a plausible LTE deployment in a mid-size metropolitan area, based on data obtained from an operator and using detailed models of heterogeneous devices, traffic, and physical layers. The metrics of interest are operator-energy-consumption/total-energy-consumption per unit of network capacity. For the scenarios we studied, we observe the following: (1) There is no significant difference between operator energy consumption of femto and macro-micro deployment strategies. This differs from the previous findings, which compared the energy consumption of femto and macro-micro deployment strategies, and found that femto deployment is considerably more energy efficient. (2) The deployment of femto base stations has a positive effect on mobile-terminal energy consumption; however, it is not significant compared to the macro-micro deployment strategy. (3) The energy saving that could be obtained by making macro and micro base stations more energy proportional is much higher than that of femto deployment.

SIPp-DD: SIP DDoS Flood-Attack Simulation Tool

  • Autoři: Staněk, J., Dr. Mgr. Lukáš Kencl,
  • Publikace: 2011 Proceedings of 20th International Conference on Computer Communications and Networks. Piscataway: IEEE, 2011. p. 1-7. ISSN 1095-2055. ISBN 978-1-4577-0638-7.
  • Rok: 2011
  • DOI: 10.1109/ICCCN.2011.6005946
  • Odkaz: https://doi.org/10.1109/ICCCN.2011.6005946
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    With the growing popularity of Voice-over-IP communication and of the SIP protocol, mobile networks including, denial-of-service attacks against the signaling are an increasingly menacing threat. We present SIPp-DD, a tool for generating real-like SIP DDoS flood attacks. SIPp-DD modifies the popular SIPp call generator and offers the option to spoof source IP addresses and ports of the generated messages. For flexibility, any set of source IP addresses and ports can be input, using a text file. To create real-like attacks, we analyze some of the publicly available DDoS flood attacks, derive typical distributions of address and packet populations and employ those in attack generation. We compare the generator outputs with the real analyzed DDoS floods and demonstrate the tool applicability by performing a DDoS attack within a real SIP-server testbed.

3D Talking-Head Interface to Voice-Interactive Services on Mobile Phones

  • Pracoviště: Katedra telekomunikační techniky, Katedra počítačové grafiky a interakce
  • Anotace:
    We present a novel framework for easy creation of interactive, platform-independent voice-services with an animated 3D talking-head interface, on mobile phones. The framework supports automated multi-modal interaction using speech and 3D graphics. We address the difficulty of synchronizing the audio stream to the animation and discuss alternatives for distributed network control of the animation and application logic. We document the ability of modern mobile devices to handle such applications and show that the power consumption trade-off of rendering on the mobile phone versus streaming from the server favors the phone.

DNA-inspired information concealing: A survey

  • Autoři: Dr. Mgr. Lukáš Kencl, Loebl, M.
  • Publikace: Computer Science Review. 2010, 4(4), 251-262. ISSN 1574-0137.
  • Rok: 2010
  • DOI: 10.1016/j.cosrev.2010.07.001
  • Odkaz: https://doi.org/10.1016/j.cosrev.2010.07.001
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Various research efforts would benefit from the ability to exchange and share information (traces with packet payloads, or other detailed system logs) to enable more data-driven research. Protection of the sensitive content is crucial for extensive information sharing. We present results of Kencl and Loebl (2009) [41] and Blamey et al. (in preparation) [4] about a technique of information concealing, based on introduction and maintenance of families of repeats. A large proportion of eukaryotic genomes is composed of DNA segments that are repeated. As yet, no function has been associated with many of the repeats. Blamey et al. (in preparation) propose that in eukaryotes the cells have DNA as a depositary of concealed genetic information and the genome achieves the self-concealing by accumulation and maintenance of repeats. The protected information may be shared and this is useful for the development of intercellular communication and in the development of multicellular organisms.

e-Scribe: Ubiquitous Real-Time Speech Transcription for the Hearing-Impaired

  • Autoři: Bumbálek, Z., Zelenka, J., Dr. Mgr. Lukáš Kencl,
  • Publikace: COMPUTERS HELPING PEOPLE WITH SPECIAL NEEDS, PROCEEDINGS. Berlin: Springer-Verlag, 2010. pp. 160-168. Lecture Notes in Computer Science. ISSN 0302-9743. ISBN 978-3-642-14096-9.
  • Rok: 2010
  • DOI: 10.1007/978-3-642-14100-3_25
  • Odkaz: https://doi.org/10.1007/978-3-642-14100-3_25
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Availability of real-time speech transcription anywhere, anytime, represents a potentially life-changing opportunity for the hearing-impaired to improve their communication capability.We present e-Scribe, a prototype web-based online centre for real-time speech transcription for the hearing-impaired, which provides ubiquitous access to speech transcription utilizing contemporary communication technologies.

Energy Savings for Cellular Network with Evaluation of Impact on Data Traffic Performance

  • Autoři: Dufková, K., Bjelica, M., Moon, B., Dr. Mgr. Lukáš Kencl, Le Boudec, J.-Y.
  • Publikace: Proceedings of European Wireless Conference. Piscataway: IEEE, 2010. pp. 916-923. ISBN 978-1-4244-5999-5.
  • Rok: 2010

Performance Study of Active Tracking in a Cellular Network Using a Modular Signaling Platform

  • Autoři: Ficek, M., Pop, T., Vláčil, P., Dufková, K., Dr. Mgr. Lukáš Kencl, Tomek, M.
  • Publikace: Proceedings of the 8th international conference on Mobile systems, applications, and services. New York: ACM, 2010. pp. 239-254. ISBN 978-1-60558-985-5.
  • Rok: 2010
  • DOI: 10.1145/1814433.1814458
  • Odkaz: https://doi.org/10.1145/1814433.1814458
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    We present the SS7Box modular signaling platform, a tool for rapid application prototyping in a cellular mobile network, and examine in detail its performance limits for the application of active network-based tracking, called SS7Tracker. This application is a highly configurable, non-intrusive and cost-effective solution for large-scale data collection on user mobility in the network, uniquely enabling tracking of both active and passive mobile clients. We present performance studies of real deployment in an existing cellular network and document the measured as well as simulated performance limits such as platform interconnection utilization. Other factors, such as impact on battery consumption of the tracked device, are studied as well. Platform modularity and variability is discussed and demonstrated by further deployed use cases. We conclude by observing promising applicability for future cellular networks.

Reduction of Animated Models for Embedded Devices

  • Pracoviště: Katedra telekomunikační techniky, Katedra počítačové grafiky a interakce
  • Anotace:
    We present a new supplementary method for reduction of animated 3D polygonal models. The method is applicable mainly in animation of human faces and it is based on intelligent merging of visemes represented by key polygonal meshes. It is useful for devices with limited CPU and memory resources like mobile phones or other embedded devices. Using this approach we can reduce operation memory needs and time to load the model from storage. We describe the algorithm for viseme merging and we prove that our method is optimal for selected metrics. Finally we validate method performance on an example and compare with the case when only traditional methods for 3D models reduction are used.

Spatial Extension of the Reality Mining Dataset

  • Autoři: Ficek, M., Dr. Mgr. Lukáš Kencl,
  • Publikace: The 7th IEEE International Conference on Mobile Ad-hoc and Sensor Systems. New York: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2010. pp. 666-673. ISBN 978-1-4244-7489-9.
  • Rok: 2010
  • DOI: 10.1109/MASS.2010.5663788
  • Odkaz: https://doi.org/10.1109/MASS.2010.5663788
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Data captured from a live cellular network with the real users during their common daily routine help to understand how the users move within the network. Unlike the simulations with limited potential or expensive experimental studies, the research in user-mobility or spatio-temporal user behavior can be conducted on publicly available datasets such as the Reality Mining Dataset. These data have been for many years a source of valuable information about social interconnection between users and user-network associations. However, an important, spatial dimension is missing in this dataset. In this paper, we present a methodology for retrieving geographical locations matching the GSM cell identifiers in the Reality Mining Dataset, an approach base on querying the Google Location API. A statistical analysis of the measure of success of locations retrieval is provided. Further, we present the LAC-clustering method for detecting and removing outliers.

Client-Server Talking Head on Mobile

  • Autoři: Danihelka, J., Dr. Mgr. Lukáš Kencl, Hák, R.
  • Publikace: Proceedings of the International Conference on Advances in Computer Enterntainment Technology. New York: ACM, 2009. pp. 1. ISBN 978-1-60558-864-3.
  • Rok: 2009
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    We propose a novel architecture for implementing a voice-interactive, automated 3D talking head on a PDA-phone, using commonly available tools. Graphics and speech components support automated multi-modal interaction. The architecture allows to easily compose varieties of representations and applications, including entertainment, commerce and education. We validate the concept by presenting a prototype implementation.

Improving Roamer Retention By Exposing Weak Locations in GSM Networks

  • Autoři: Ficek, M., Dr. Mgr. Lukáš Kencl,
  • Publikace: CoNEXT Student Workshop 09. New York: ACM, 2009. pp. 17-18. ISBN 978-1-60558-751-6.
  • Rok: 2009
  • DOI: 10.1145/1658997.1659007
  • Odkaz: https://doi.org/10.1145/1658997.1659007
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    One of the most valuable clients of cellular GSM networks are roaming clients, due to the pricing policy set by network operators. Despite that each operator applies a lot of effort in network signal coverage in order to achieve the best conditions for roaming traffic in the network, there still remain hardly detectable locations where roaming clients are getting lost to rival networks. This paper presents a roaming traffic weak locations revealing method based on active tracking of roamer location in a live GSM network. We define the problem scope using formal description of an active tracking process and propose a metrics for network "weakness" evaluation together with intuitive visualization of weak locations. We shortly conclude with plans of our ongoing research.

Predicting User-Cell Association in Cellular Networks from Tracked Data

  • Autoři: Dufková, K., Le Boudec, J.-Y., Dr. Mgr. Lukáš Kencl, Bjelica, M.
  • Publikace: Mobile Entity Localization and Tracking in GPS-less Environnments. Berlin: Springer, 2009. p. 19-33. Lecture Notes in Computer Science. ISSN 0302-9743. ISBN 978-3-642-04378-9.
  • Rok: 2009
  • DOI: 10.1007/978-3-642-04385-7_2
  • Odkaz: https://doi.org/10.1007/978-3-642-04385-7_2
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    We consider the problem of predicting user location in the form of user-cell association in a cellular wireless network. This is motivated by resource optimization, for example switching base transceiver stations on or off to save on network energy consumption.

Voice2Web: Architecture for Managing Voice-Application Access to Web Resources

  • Autoři: Rudinský, J., Mikula, T., Dr. Mgr. Lukáš Kencl, Doležal, J., Garcia, X.
  • Publikace: Wired-Wireless Multimedia Networks and Services Management. Berlin: Springer, 2009, pp. 118-131. Lecture Notes in Computer Science (LNCS). ISSN 0302-9743. ISBN 978-3-642-04993-4. Available from: http://www.springerlink.com/content/k8832375t9x52883/?p=539072a11ded49faa331776524d33be8&pi=9
  • Rok: 2009
  • DOI: 10.1007/978-3-642-04994-1_10
  • Odkaz: https://doi.org/10.1007/978-3-642-04994-1_10
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Advances in voice-recognition platforms have led to new possibilities in deploying automated voice-interactive engines for Web content. We present Voice2Web, an architecture allowing to manage access to the resources of the World Wide Web using voice interaction. It rests on the VoiceXML standard and enables rapid composition of dynamic services querying the Web resources. We demonstrate its use on practical examples, discuss architecture implications and invite further platform experimentation.

Active GSM cell-id tracking: "Where Did You Disappear?"

  • Autoři: Dufková, K., Ficek, M., Dr. Mgr. Lukáš Kencl, Novák, J., Kouba, J., Gregor, I., Danihelka, J.
  • Publikace: Proceedings of the first ACM international workshop on Mobile entity localization and tracking in GPS-less environments. New York: ACM, 2008. p. 7-12. ISBN 978-1-60558-189-7.
  • Rok: 2008
  • DOI: 10.1145/1410012.1410015
  • Odkaz: https://doi.org/10.1145/1410012.1410015
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    Location-based services are mobile network applications of growing importance and variability. The space of location technologies and applications has not yet been fully explored, perhaps omitting some important practical uses. In this work we present the prototype SS7Tracker platform, an active, non-intrusive, GSM Cell-ID-based solution to network-based location tracking, and two novel applications of this technique: network diagnostics based on inroamer tracking and human activity research. We demonstrate the usability and performance limits of the platform on practical tests carried out in a live GSM network.

Adaptive Load Sharing for Network Processors

  • Autoři: Dr. Mgr. Lukáš Kencl, Le Boudec, J.-Y.
  • Publikace: IEEE/ACM Transactions on Networking. 2008, 16(3), 293-306. ISSN 1063-6692.
  • Rok: 2008
  • DOI: 10.1109/TNET.2007.909839
  • Odkaz: https://doi.org/10.1109/TNET.2007.909839
  • Pracoviště: Katedra telekomunikační techniky
  • Anotace:
    A novel scheme for processing packets in a router is presented that provides load sharing among multiple network processors distributed within the router. It is complemented by a feedback control mechanism designed to prevent processor overload. Incoming traffic is scheduled to multiple processors based on a deterministic mapping.

Za stránku zodpovídá: Ing. Mgr. Radovan Suk