Inst. Telekommunikationssysteme

336 Items

Recent Submissions
A Year in Lockdown: How the Waves of COVID-19 Impact Internet Traffic

Feldmann, Anja ; Gasser, Oliver ; Lichtblau, Franziska ; Pujol, Enric ; Poese, Ingmar ; Dietzel, Christoph ; Wagner, Daniel ; Wichtlhuber, Matthias ; Tapiador, Juan ; Vallina-Rodriguez, Narseo ; Hohlfeld, Oliver ; Smaragdakis, Georgios (2021-06)

In March 2020, the World Health Organization declared the COVID-19 outbreak a global pandemic. As a result, billions of people were either encouraged or forced by their governments to stay home to reduce the spread of the virus. This caused many to turn to the Internet for work, education, social interaction, and entertainment. With the Internet demand rising at an unprecedented rate, the quest...

A view of Internet Traffic Shifts at ISP and IXPs during the COVID-19 Pandemic

Feldmann, Anja ; Gasser, Oliver ; Lichtblau, Franziska ; Pujol, Enric ; Poese, Ingmar ; Dietzel, Christoph ; Wagner, Daniel ; Wichtlhuber, Matthias ; Tapiador, Juan ; Vallina-Rodriguez, Narseo ; Hohlfeld, Oliver ; Smaragdakis, Georgios (2020-11)

Due to the COVID-19 pandemic, many governments imposed lockdowns that forced hundreds of millions of citizens to stay at home. The implementation of confinement measures increased Internet traffic demands of residential users, in particular, for remote working, entertainment, commerce, and education, which, as a result, caused traffic shifts in the Internet core. In this paper, using data from ...

Identifying Sensitive URLs at Web-Scale

Matic, Srdjan ; Iordanou, Costas ; Smaragdakis, Georgios ; Laoutaris, Nikolaos (2020-10-27)

Several data protection laws include special provisions for protecting personal data relating to religion, health, sexual orientation, and other sensitive categories. Having a well-defined list of sensitive categories is sufficient for filing complaints manually, conducting investigations, and prosecuting cases in courts of law. Data protection laws, however, do not define explicitly what type ...

Who's left behind? Measuring Adoption of Application Updates at Scale

Rula, John P. ; Richter, Philipp ; Smaragdakis, Georgios ; Berger, Arthur (2020-10-27)

This work presents a large-scale, longitudinal measurement study on the adoption of application updates, enabling continuous reporting of potentially vulnerable software populations worldwide. Studying the factors impacting software currentness, we investigate and discuss the impact of the platform and its updating strategies on software currentness, device lock-in effects, as well as user beha...

Keep your Communities Clean: Exploring the Routing Message Impact of BGP Communities

Krenc, Thomas ; Beverly, Robert ; Smaragdakis, Georgios (2020-11-23)

BGP communities are widely used to tag prefix aggregates for policy, traffic engineering, and inter-AS signaling. Because individual ASes de ne their own community semantics, many ASes blindly propagate communities they do not recognize. Prior research has shown the potential security vulnerabilities when communities are not filtered. This work sheds light on a second unintended side-effect of ...

Exploring Network-Wide Flow Data with Flowyager

Saidi, Said Jawad ; Maghsoudlou, Aniss ; Foucard, Damien ; Smaragdakis, Georgios ; Poese, Ingmar ; Feldmann, Anja (2020-10-27)

Many network operations, ranging from attack investigation and mitigation to traffic management, require answering network-wide flow queries in seconds. Although flow records are collected at each router, using available traffic capture utilities, querying the resulting datasets from hundreds of routers across sites and over time, remains a significant challenge due to the sheer traffic volume ...

A Haystack Full of Needles: Scalable Detection of IoT Devices in the Wild

Saidi, Said Jawad ; Mandalari, Anna Maria ; Kolcun, Roman ; Haddadi, Hamed ; Dubois, Daniel J. ; Choffnes, David ; Smaragdakis, Georgios ; Feldmann, Anja (2020-10-27)

Consumer Internet of Things (IoT) devices are extremely popular, providing users with rich and diverse functionalities, from voice assistants to home appliances. These functionalities often come with significant privacy and security risks, with notable recent large-scale coordinated global attacks disrupting large service providers. Thus, an important first step to address these risks is to kno...

The Lockdown Effect: Implications of the COVID-19 Pandemic on Internet Traffic

Feldmann, Anja ; Gasser, Oliver ; Lichtblau, Franziska ; Pujol, Enric ; Poese, Ingmar ; Dietzel, Christoph ; Wagner, Daniel ; Wichtlhuber, Matthias ; Tapiador, Juan ; Vallina-Rodriguez, Narseo ; Hohlfeld, Oliver ; Smaragdakis, Georgios (2020-10-27)

Due to the COVID-19 pandemic, many governments imposed lockdowns that forced hundreds of millions to stay at home. As a result of these measures, Internet traffic of residential users increased, in particular, for remote working, entertainment, commerce, and education. In turn, traffic demands in the Internet core shifted as well. In this paper, using data from a diverse set of vantage points ...

On the Hardness and Inapproximability of Virtual Network Embeddings

Rost, Matthias ; Schmid, Stefan (2020-03-05)

Many resource allocation problems in the cloud can be described as a basic Virtual Network Embedding Problem (VNEP): the problem of finding a mapping of a request graph (describing a workload) onto a substrate graph (describing the physical infrastructure). Applications range from mapping testbeds, over the embedding of batch-processing workloads to the embedding of service function chains and ...

Information Bottleneck for a Rayleigh Fading MIMO Channel with an Oblivious Relay

Xu, Hao ; Yang, Tianyu ; Caire, Giuseppe ; Shamai Shitz, Shlomo (2021-04-08)

This paper considers the information bottleneck (IB) problem of a Rayleigh fading multiple-input multiple-out (MIMO) channel with an oblivious relay. The relay is constrained to operating without knowledge of the codebooks, i.e., it performs oblivious processing. Moreover, due to the bottleneck constraint, it is impossible for the relay to inform the destination node of the perfect channel stat...

Trust Mining: Analyzing Trust in Collaborative Business Processes

Müller, Marcel ; Ostern, Nadine ; Koljada, Denis ; Grunert, Kai ; Rosemann, Michael ; Küpper, Axel (2021-04-26)

The ongoing digital transformation and internationalization of business processes cause a shift towards a more collaborative nature of processes. In such collaborations, different organizations execute separate parts of the process autonomously. This fragmentation leads to uncertainty regarding the correct execution of activities, the proper workflow, and data in the process flow. If organizati...

Design of a cooperative overtaking algorithm for platoons on freeways

Strunz, Martin (2021)

Platooning can improve road safety, optimize traffic flow, and raise the driver’s comfort. However, when a platoon is stuck behind a slower vehicle, the total travel time is significantly increased. Overtaking as a whole platoon is a complicated maneuver and there is no communication-based algorithm for this task so far. Therefore, we design such a cooperative overtaking algorithm for platoons ...

Deep anomaly detection in distributed software systems

Nedelkoski, Sasho (2021)

Artificial Intelligence for IT Operations (AIOps) combines big data and machine learning to replace a broad range of IT Operations tasks. The task of anomaly detection has a prominent position in ensuring the required reliability and safe operation in distributed software systems. However, the frequent software and hardware updates, system heterogeneity, and massive amount of data create a chal...

Predicting How to Test Requirements: An Automated Approach

Winkler, Jonas Paul ; Grönberg, Jannis ; Vogelsang, Andreas (2019-12-05)

[Context] An important task in requirements engineering is to identify and determine how to verify a requirement (e.g., by manual review, testing, or simulation; also called potential verification method). This information is required to effectively create test cases and verification plans for requirements. [Objective] In this paper, we propose an automatic approach to classify natural language...

Optimizing for Recall in Automatic Requirements Classification: An Empirical Study

Winkler, Jonas Paul ; Grönberg, Jannis ; Vogelsang, Andreas (2019-12-05)

Using Machine Learning to solve requirements engineering problems can be a tricky task. Even though certain algorithms have exceptional performance, their recall is usually below 100%. One key aspect in the implementation of machine learning tools is the balance between recall and precision. Tools that do not find all correct answers may be considered useless. However, some tasks are very com...

Improving Trace Link Recovery using Semantic Relation Graphs and Spreading Activation

Schlutter, Aaron ; Vogelsang, Andreas (2021-04-02)

[Context & Motivation] Trace Link Recovery tries to identify and link related existing requirements with each other to support further engineering tasks. Existing approaches are mainly based on algebraic Information Retrieval or machine-learning. [Question/Problem] Machine-learning approaches usually demand reasonably large and labeled datasets to train. Algebraic Information Retrieval approach...

Sparse recovery based grant-free random access for massive machine-type communication

Fengler, Alexander (2021)

This dissertation treats a recently introduced modern random access protocol known as unsourced random access (U-RA). This protocol belongs to the family of grant-free random access protocols which, in contrast to the established grant-based protocols of current mobile communication standards, do not rely on an initial access phase, in which the active devices identify themselves and await the ...

Frequency division duplexing massive MIMO

Barzegar Khalilsarai, Mahdi (2021)

Massive Multiple-Input Multiple-Output (MIMO) systems are envisioned for employment in the upcoming generations of wireless communication networks. The characteristic of these systems is the use of a large number of antenna elements (M>>1) in the Base Station (BS) array, that enables data transmission to several users via spatial multiplexing. These systems enjoy favorable communication propert...

What Am I Testing and Where? Comparing Testing Procedures Based on Lightweight Requirements Annotations

Pudlitz, Florian ; Brokhausen, Florian ; Vogelsang, Andreas (2021-02)

The article was originally published in the international journal Empirical Software Engineering with the title "What am I testing and where? Comparing testing procedures based on lightweight requirements annotations."

Robust learning in wireless networks

Awan, Daniyal Amir (2021)

This work studies robust learning in dynamic wireless environments. Modern wireless data networks are complex and modeling their behavior accurately is difficult. As a result, machine learning and artificial intelligence have been making significant inroads into wireless networks. State-of-the-art machine learning algorithms (e.g., neural networks) assume a stationary learning environment and t...