Seminar

Driven by the requirements of innovative applications and services, the past few years have produced new technologies for networked or distributed systems. In the Internet of Things, a large number of devices and everyday objects equipped with sensors and actuators are connected to the internet and communicate through mostly wireless communication technologies (e.g., BLE, ZigBee, 6LoWPAN, LoRaWAN). In one of its sub-domains, the industrial Internet of Things (IIoT, Industry 4.0), machines, tools, transport equipment, etc. are networked.
Virtualisation (e.g., NFV) and "software-defined" systems (e.g., SDN), increase the flexiblity and efficiency of distributed systems through dynamic adaptation and scaling.
Driven by the popularity of the Bitcoin system, distributed ledger technologies and related concepts such as smart contracts have been developed, which are not only the foundations of electronic currencies, but can also support any application in which a consensus between different parties must be reached and documented. 
Another focus has been the reduction of latency in networked and distributed systems, e.g. by using nearby edge and fog computing resources in addition to the remote cloud, or by using optimised communication protocols to., for instance, rapidly connect client and server. 
In addition to stationary networks, mobile (5G) communication technologies and systems have developed rapidly. For example, the Covid-19 tracing application uses mobile devices to track contacts. This method, known as crowdsensing, can be used more generally to collect large amounts of geographically distributed sensor data. 

This seminar will discuss a wide range of current technologies, protocols and standards that enable the above networked and distributed applications and services.

Organization: The seminar is organized in the style of a scientific conference. Following the submission of a written paper on the assigned topic, students write reviews for other seminar papers and participate in a final presentation session where they present their work and discuss the work of others. Attendance at the kick-off and final presentation session is mandatory.

Prerequisite: Successful completion of at least 1 course at the department of Distributed Systems is highly recommended.

High-Throughput Communication

Topic 1: Media Access Control in IEEE 802.11 Networks
Supervisor: Jona Herrmann

Wireless Local Area Networks (WLANs) based on the IEEE 802.11 standard are very important for mobile devices, as this is the only way they can access the network and finally the Internet. Typically, many devices are connected to the same WLAN and use it at the same time. Therefore, a Media Access Control (MAC) protocol is necessary for coordinating access to the shared medium.

Goals of the seminar paper:

• Why can the MAC protocol of IEEE 802.3 networks not be used in IEEE 802.11 networks?
• Explain DCF und PCF in detail
• Explain Quality of Service improvements (IEEE 802.11e)

Topic 2: Multi-Link Operation in IEEE 802.11be
Supervisor: Jona Herrmann

The IEEE 802.11be standard introduces Multi-Link Operation (MLO), which enables devices to operate concurrently over multiple channels, either within or across frequency bands. By distributing traffic over these parallel links, MLO reduces latency and congestion on any single channel while increasing total throughput. Consequently, MLO improves the reliability and efficiency of IEEE 802.11be networks.

Goals of the seminar paper:

• Explain the MLO technique in IEEE 802.11be
• A literature review on the real-world performance evaluation of MLO

Topic 3: QUIC -The fast TCP alternative
Supervisor: Michael Schramm

For large web companies and Content Distribution Networks the performance and security of web protocols is of big concern. Out of this reasons Google proposed the QUIC protocol. All mobile apps from Google support QUIC and in October 2020 more than 75% of the Meta internet traffic uses QUIC making it to the standard internet protocol at Meta [1].

How does this upcoming protocol ensure security? How is the higher performance achieved and how much higher is it? What is the Packet Pacing, which is used in QUIC and why can it be beneficial compared to techniques used in TCP (e.g. Fast Retransmit)?

Goals of the seminar paper:   

• Explain the QUIC protocol
• Compare it with the TCP protocol variants
• Write about performance measurements and experiences with the QUIC protocol.

Cloud and Edge Computing

Topic 4: AI for the Edge
Supervisor: Michael Schramm

With the evolving mobile communication technologies edge computing theory and techniques have been attracted an increasing interest of researchers and engineers around the world. Edge computing can help to accelerate content delivery and reduce network load, by communicating with near edge nodes instead of the cloud.

Artificial Intelligence (AI) is increasingly used to enhance the performance, scalability, and efficiency of edge computing environments. AI-driven techniques help in dynamic resource allocation, predictive maintenance and real-time workload distribution. By leveraging machine learning and deep learning models, edge networks can self-optimize, adapt to changing conditions, and reduce operational costs.

Goals of the seminar paper:

• Describe approaches which use AI to optimize edge computing environments.
• Discuss the benefits and limitations of AI-driven edge optimization.
• Examine the trade-offs between computational overhead and performance gains.

Topic 5: Remote Procedure Calls (RPC) in Modern Cloud Applications
Supervisor: Sven Feyerabend

Modern cloud applications are characterized by their global distribution and the need to serve millions of concurrent users. To manage this complexity and ensure scalability, these applications often move away from monolithic designs toward microservice architectures. In such environments, the overall functionality of a system emerges from the interaction of hundreds or even thousands of individual, decoupled components. This shift has placed a renewed focus on efficiency and reliability of inter-service communication.

While REST-based APIs (typically using HTTP/1.1 and JSON) have long been the industry standard, they often introduce overhead that can become a bottleneck in high-throughput, low-latency cloud environments. As a result, Remote Procedure Calls (RPC) have seen a resurgence. In particular, the gRPC framework—leveraging Protocol Buffers for serialization and HTTP/2 for transport—has emerged as a powerful alternative.

Goals of the seminar paper:

• Fundamentals: What is the underlying paradigm of RPC, and how does it differ from resource-oriented architectures like REST?
• Technology Stack: How does a modern framework like gRPC work? Discuss the role of Interface Definition Languages (IDLs), code generation, and the advantages of the binary Protocol Buffer format.
• Performance & Scalability: How does RPC perform in cloud-native applications? Analyze performance characteristics (at scale), either through a comparison with REST-based communication or through a survey of different RPC frameworks (e.g., gRPC, ONC RPC, WebRPC, etc.) and their respective trade-offs.

Secure Communication

Topic 6: The Fragmented Web: Technical Mechanisms and Measurement of Internet Censorship
Supervisor: Sven Feyerabend

The Internet was originally designed to connect systems reliably and indiscriminately, routing traffic seamlessly around disruptions. However, the modern reality diverges significantly from this vision. As the web grew, network operators introduced firewalls and segregated networks to defend against malicious actors.

Yet, the very same technologies designed to protect private networks have been co-opted on a massive scale. Today, various jurisdictions heavily diverge on what they consider appropriate or legal. This has led to a rise in state-level and organizational interference, with authorities deploying sophisticated network security tools as censorship mechanisms to impede their citizens' access to global communication and content.

Goals of the seminar paper:

• Censorship Mechanisms: Give a structured overview of modern, network-level censorship techniques. How do wardens (censors) influence access to online resources?
• Measurement Methodologies: How do researchers detect blockages without being physically present in the censored region?
• Limitations and Evasion: Give a brief overview of popular technologies (e.g., VPNs, Tor, etc.) that can be used to bypass regional restrictions.

Topic 7: Tor - The Onion Router
Supervisor: Lukas Epple

Tor is a popular anonymity network that allows users to browse the Internet without revealing their true identity, location, or activity. By routing Internet traffic through a series of encrypted nodes or relays, the source of the traffic is obscured and user privacy is maintained.

Goals of the seminar paper:

• Provide a comprehensive overview of Tor and its technical underpinning by exploring how Tor works internally and how it achieves privacy.
• Review the potential risks and limitations of Tor.
• Discuss the impact of Tor on Internet privacy and security.

Topic 8: I2P - The Invisible Internet
Supervisor: Lukas Epple

I2P is a self-contained network that ensures secure and anonymous communication between users. Unlike other anonymity networks, I2P focuses on providing a private communication layer within its own boundaries, rather than enabling access to the wider Internet. In this seminar topic, we will explore the pivotal role of I2P in the realm of anonymous online communication

Goals of the seminar paper:

• Navigate through the key points of the I2P architecture.
• Discuss the use of garlic routing to encrypt and bundle messages.
• Examine the various applications intrinsic to the I2P ecosystem.
• Analyze the network's limitations and vulnerabilities.

Topic 9: Secure Gaze Data Transmission
Supervisor: Melanie Heck

A person's eye movements can be used as a control mechanism, to design adaptive interfaces that respond to the user's current state to dynamically offer support, or as an alternative authentication method. In order to extract meaningful information from gaze data, sophisticated algorithms are used that require considerable amounts of computational power. Typically, the raw gaze data is therefore sent to powerful servers, often over unsecure networks. As the gaze is classified as highly sensitive biometric data, this transmission imposes a significant threat to security and privacy. While local preprosessing of the gaze data (e.g., differential privacy approaches) can mitigate some of these concerns, they are typically not suitable when gaze is used for authentication purposes.

Goals of the seminar paper:

• Review approaches that have been proposed in scientific literature to ensure the safe transmission of gaze data while maintaining the identifiable features in the data that are necessary for gaze-based authentication.
• Compare the identified approaches in terms of the strength of the security that they promise, as well as their remaining risks and potential drawbacks.
• Discuss the applicability of the approaches in different contextual settings.

IoT Networks

Topic 10: Vehicle Software Architectures
Supervisor: Melanie Heck

The automotive industry is increasingly shifting from hardware-centric architectures towards software defined vehicles (SDVs), where features and functions are primarily enabled und updated through software. Over the years, SDV architectures have evolved from a distributed to a centralized model in order to better accommodate emerging technologies and new requirements of modern vehicles.

Goals of the seminar paper:

• Systematically compare the predominant software-defined vehicle architectures and characterize how they have evolved over time.
• Discuss the current state of industry and academic research.
• Identify the advantages and challenges of the reviewed vehicle architectures.

Topic 11: Building Infrastructureless Networks: Real-World Ad Hoc Communication on Low-Cost Hardware
Supervisor: Julian Siebert

When rapid deployment and flexibility are essential, decentralized architectures offer a significant advantage over traditional systems. Wireless Ad-Hoc Networks (WANETs) excel here by enabling independent nodes to spontaneously form networks. This is highly valuable for quickly establishing communication in remote, dynamic, or infrastructure-deprived environments.

While WANET concepts are well-established, real-world deployment on low-cost microcontrollers like the ESP32 introduces practical hurdles. Running standard routing protocols, such as Ad hoc On-Demand Distance Vector (AODV), efficiently on resource-constrained hardware can be challenging. Physical environments heavily impact network stability, especially when devices are sparsely distributed and fluctuating link quality dictates reliable route establishment.

Goals of the seminar paper:

• Introduce Wireless Ad-Hoc Networks (WANETs) and decentralized routing protocols.
• Explain the technical challenges of running protocols like AODV on low-cost microcontrollers.
• Analyze the impact of real-world physical constraints, focusing on how fluctuating link quality dictates route selection in sparse topologies.

Topic 12: GeoNetworking in V2X Communication: Technical Foundations and Routing Strategies
Supervisor: Julian Siebert

Vehicle-to-Everything (V2X) communication enables vehicles to wirelessly exchange real-time information with their entire environment, including other cars, traffic lights, and pedestrians. However, this technology faces a unique challenge: cars are constantly moving, making traditional internet routing (like using fixed IP addresses) too slow and unreliable for fast-paced traffic. To solve this, the European Telecommunications Standards Institute (ETSI) created a specialized approach for Intelligent Transport Systems (ITS) called GeoNetworking.

Unlike conventional networking, GeoNetworking routes data packets based on geographical coordinates and areas rather than network addresses. This spatial approach allows vehicles to efficiently disseminate critical, time-sensitive information—such as hazard warnings or cooperative awareness messages—to all relevant recipients within a specific physical area (GeoBroadcast). Understanding the technical mechanics of this protocol is essential for implementing reliable, low-latency V2X applications in real-world traffic scenarios.

Goals of the seminar paper:

• Provide a technical overview of the ETSI ITS station architecture and the specific role of the GeoNetworking layer.
• Explain core geographical routing mechanisms and addressing schemes, such as GeoBroadcast, GeoUnicast, and Topologically-Scoped Broadcast.
• Analyze the technical challenges of GeoNetworking, including managing high vehicular mobility, dynamic network changes, and efficient data dissemination.

Topic 13: LoRa and LoRaWAN for Long-Range Wireless Communication
Supervisor: Justin Schiel

The increasing number of connected devices in the Internet of Things requires wireless communication technologies that support long transmission ranges while maintaining low energy consumption. Many traditional wireless technologies, such as Wi-Fi or Bluetooth, are designed for short-range, high-throughput communication and are therefore not well suited for large-scale sensor deployments. Low-power wide-area network (LPWAN) technologies address this challenge by enabling long-distance communication with minimal energy usage. One of the most prominent technologies in this domain is LoRa.

Goals of the seminar paper:

• Comprehensive review of relevant literature and technical documentation on the LoRa wireless communication technology and its use in IoT systems.
• Describe the fundamental principles of LoRa communication, including its modulation scheme and its integration within the LoRaWAN network architecture.
• Discuss how configuration parameters such as spreading factor, bandwidth, and coding rate, as well as transmission power and data rate influence communication range, reliability, energy consumption, and network capacity.
• Discuss advantages and limitations of LoRa-based communication.
• Describe typical application scenarios.

Topic 14: Zigbee Network Architecture and Routing in Low-Power Wireless Networks
Supervisor: Justin Schiel

Wireless communication is crucial for enabling connectivity between devices in smart home and IoT environments. These systems often consist of numerous small devices with limited computational resources and energy budgets, requiring communication protocols that are both efficient and scalable. Zigbee is a widely used wireless technology designed specifically for such low-power, low-data-rate applications and supports mesh networking, thereby extending the communication range and improving network robustness.

Goals of the seminar paper:

• Review of relevant standards and scientific literature on the architecture and communication mechanisms of Zigbee networks.
• Describe the different roles of devices in a Zigbee network, including coordinators, routers, and end devices, and explain how these components interact to form a mesh network.
• Analyze how Zigbee networks manage device discovery, routing, and message forwarding. Give particular attention to the routing mechanisms and processes by which messages are transmitted across multiple nodes to reach their destination.
• Discuss advantages and limitations of Zigbee in smart home and IoT environments.

Topic 15: CoAP: Constrained Application Protocol
Supervisor: Simon Egger

Typical IoT devices are often resource constrained and cannot tolerate the computational overhead of TCP/IP + HTTP + REST. CoAP aims to provide a more light-weight alternative for such platforms. [1]

Goals of the seminar paper:

• Motivate the usage of CoAP in resource-constrained environments.
• Provide a technical introduction to CoAP, including the underlying message format and protocols (e.g., for service discovery).
• Discuss trade-offs and limitations of CoAP (e.g., regarding security guarantees).

Time-Sensitive Networks

Topic 16: DECT NR+
Supervisor: Simon Egger

DECT NR+ is a non-cellular 5G technology standard that specializes on ultra-high reliability and ultra-low latency (>99.99% reliability at sub-millisecond latencies). This seminar topic aims to provide a technical introduction to the central DECT NR+ mechanisms that enable such guarantees.

[1] ETSI TS 103 636-1, DECT-2020 New Radio (NR); Part 1: Overview

Goals of the seminar paper:

• Motivate the usage of DECT NR+ compared to public/private 5G deployments.
• Provide a technical introduction to DECT NR+, including its physical layer and media access control (MAC) layer.
• Discuss potential applications and technical limitations of DECT NR+.

Topic 17: Deterministic Real-Time Communication with Time-Sensitive Networking
Supervisor: Lucas Haug

Real-time communication with deterministic bounds on network delay and jitter is crucial for the efficient and safe operation of networked real-time systems. As distributed Cyber-Physical Systems (CPSs) with networked sensors, actuators, and controllers become increasingly popular in various domains such as Industrial Internet of Things (IIoT) and autonomous vehicles, the demand for deterministic real-time communication with a high reliability and bounded network delay and delay variance (jitter) has grown.

Major standardization organizations like the Institute of Electrical and Electronics Engineers (IEEE) and the Internet Engineering Taskforce (IETF) have acknowledged the necessity for deterministic networks leading to a set of standards under the term Time-Sensitive Networking (TSN), which extend standard wired IEEE 803.3 networks (Ethernet) by real-time communication mechanisms. For example, IEEE 802.1Qbv defines the Time-Aware Shaper, which enables deterministic scheduling of traffic through time-slotting. Similarly, IEEE 802.1Qbu and IEEE 802.3br introduce Frame Preemption to allow high-priority traffic to interrupt lower-priority transmissions and IEEE 802.1CB introduces Frame Replication and Elimination for Reliability (FRER).

Goals of the seminar paper:

• Give an overview over the aforementioned TSN standards and describe how they enable deterministic real-time communication.

Topic 18: gPTP – Time Synchronization for Time-Sensitive Networking
Supervisor: Lucas Haug

Accurate clock synchronization is essential in networks requiring time-critical data transfer, where even minimal clock deviations can lead to significant operational errors. Given that the internal clocks of network devices inherently drift apart over time, clock synchronization is indispensable for reliable and error-free operations.

In wired Ethernet networks, the Generalized Precision Time Protocol (gPTP), standardized in IEEE 802.1AS, provides a widely adopted solution for precise time synchronization. gPTP extends the IEEE 1588 Precision Time Protocol (PTP) and is specifically tailored for bridged local area networks. It operates on a master-slave hierarchy, where one device assumes the role of Grand Master and distributes timing information to all other nodes. To achieve sub-microsecond accuracy, gPTP relies on hardware-based timestamping of packets, thereby minimizing the impact of software-induced delays. Furthermore, the protocol incorporates mechanisms to compensate for propagation delays across network links, ensuring that all devices share a consistent notion of time even in multi-hop topologies.

Goals of the seminar paper:

• Explain the mechanisms through which gPTP achieves precise time synchronization.
• Compare gPTP to other time synchronization protocols such as NTP.

Concurrent Programs

Topic 19: Memory Ordering in the C++ Standard
Supervisor: Simon König

Controlling access to memory plays a crucial role when building concurrent programs. Programmers often assume the operations of their programs to be executed sequentially and in-order. However, optimizations applied by the compiler, the CPU pipeline and the memory management unit can cause the operations of a program to be executed out-of-order. In multi-threaded applications, this has the potential to change the semantics of the program, resulting in unexpected observed behavior. Therefore, synchronization is necessary. The usage of memory barriers allows OS-level primitives (e.g., semaphores) or lock-free data structures to provide meaningful consistency guarantees.

Goals of the seminar paper:

• Delve into the principles and mechanisms that are used to control and synchronize access to shared memory.
• Investigate the usage and semantics of memory barriers in modern memory models such as the C++ memory model.
• Focus on the theoretical model behind acquire-release or sequentially consistent memory ordering as defined by the C++ standard.

Topic 20: User-Space Mutex: Spinlocks and Atomic Synchronization
Supervisor: Simon König

This seminar topic focuses on the challenges of ensuring proper synchronization without relying on kernel-based synchronization. We will explore the concept of user-space mutex implementations, focusing particularly on spinlocks and their role in low-level synchronization within concurrent systems. We will analyze the mechanics of busy-wait locks, where threads continuously check the availability of a critical section, and the implications this has on processor utilization and cache coherence.

Goals of the seminar paper:

• Discuss spinlock implementations as synchronization primitives that avoid blocking and instead rely on active polling.
• Compare the test-and-set lock, the test-and-test-and-set lock, and MCS locks. Focus on the trade-offs in terms of efficiency under contention and multithreaded scalability.

Melanie Heck

The Internet of Everything (IoE), where virtually everything can now communicate through the Internet, and the increasingly demanding performance requirements of new technologies (e.g., cryptocurrencies) have driven the emergence of new computing paradigms for distributed systems. Scalability is now offered not only by centralized cloud providers, but also by edge computing systems, where geographically distributed servers provide computational resources at the edge of the network and, therefore, close to the end devices. This can significantly reduce latency for time-critical applications like vehicular networks. The advances in edge computing have led to the emergence of edge AI, where powerful AI algorithms are deployed at the edge, without relying on a remote cloud.

But distributed systems come with many challenges which requires a profound understanding of core principles in distributed computing. As pointed out by former Google Senior Vice President Urs Hölzl: “At scale, everything breaks ... Keeping things simple and yet scalable is actually the biggest challenge. It's really, really hard.“ This is especially true for dynamic and uncertain environments that we are facing, for instance, in smart buildings or smart energy systems. Self-adaptation is one of the key mechanisms for coping with increasingly large and dynamic systems, often by using machine learning techniques (GNN, reinforcement learning). Challenges that come with distributed storage systems include consistency and scalability.

Another hot topic, especially in the context of 5G and the development of future 6G networks, is Time Sensitive Networking (TSN), which defines a set of standards to enable reliable, deterministic real-time communication in Ethernet networks. These standards target, among others, time synchronization and traffic shaping/scheduling approaches for both event-based and time-triggered traffic.

In this seminar, we take a deep dive into specific concepts of distributed and context-aware systems that tackle the above challenges.  The topics will be published on the department’s website and are assigned according to a standardized procedure as explained during the kick-off.

Organization: The seminar is organized in the style of a scientific conference. Following the submission of a written paper on the assigned topic, students write reviews for other seminar papers and participate in a final presentation session where they present their work and discuss the work of others. Attendance at the kick-off and final presentation session is mandatory.

Prerequisite: Successful completion of at least 1 Master-level course at the department of Distributed Systems is highly recommended.

Fast & Reliable Networks

Topic 1: Multi-Link Operation in IEEE 802.11be
Supervisor: Jona Herrmann

The IEEE 802.11be standard introduces Multi-Link Operation (MLO), which enables devices to operate concurrently over multiple channels, either within or across frequency bands. By distributing traffic over these parallel links, MLO reduces latency and congestion on any single channel while increasing total throughput. Consequently, MLO improves the reliability and efficiency of IEEE 802.11be networks.

Goals of the seminar paper:

• Explain the MLO technique in IEEE 802.11be
• A literature review on the real-world performance evaluation of MLO

Topic 2: Forward Error Correction in IEEE 802.11 Networks
Supervisor: Jona Herrmann

The IEEE 802.11 standard uses Forward Error Correction (FEC) to enable receivers to identify and correct bit errors autonomously by embedding redundant parity information into the physical (PHY) layer. This mechanism increases robustness against channel impairments such as noise, interference, and multipath fading. Hence, FEC improves the reliability of links and the effective throughput in IEEE 802.11 networks.

Goals of the seminar paper:

• Why is FEC not used in IEEE 802.3?
• Explain the two different FEC techniques in IEEE 802.11
• What is the relationship between FCS and the Modulation and Coding Scheme (MCS)?
• Why is the Frame Check Sequence (FCS) still needed?

Topic 3: gPTP-based Time Synchronization in Converged 6G/TSN Networks
Supervisor: Lucas Haug

Accurate clock synchronization is essential in networks requiring time-critical data transfer, where even minimal clock deviations can lead to significant operational errors. Given that the internal clocks of network devices inherently drift apart over time, clock synchronization is indispensable for reliable and error-free operations.

In wired Ethernet networks, protocols like the Generalized Precision Time Protocol (gPTP), defined in the IEEE 802.1AS standard, are widely implemented. gPTP employs a master-slave architecture and hardware timestamping to achieve time synchronization with sub-microsecond accuracy. However, in emerging network domains – including converged 6G/TSN networks – further problems, such as variable link delays, arise. Thus, time synchronization in these fields is still under active research.

Goals of the seminar paper:

• Explain the mechanisms through which gPTP achieves precise time synchronization in traditional Ethernet-networks and how these mechanisms can be employed in converged 6G/TSN networks.

Topic 4: Radio Resource Grid Allocation for 5G Network Slicing
Supervisor: Lucas Haug

Efficient allocation of radio resources is critical in 5G networks, where diverse services such as enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC) must coexist. Network slicing enables multiple logical networks to share the same physical infrastructure while maintaining performance isolation. However, realizing slicing at the Radio Access Network (RAN) level introduces significant challenges, particularly in the allocation and scheduling of radio resources within the resource grid. Ensuring that different slices operate efficiently while minimizing interference and maximizing spectral efficiency is a key research problem.

The resource grid in 5G is a structured framework that defines how radio spectrum is divided into time-frequency units. In RAN slicing, each slice may require a different configuration in terms of bandwidth, latency, and reliability, necessitating dynamic partitioning of the resource grid. This involves defining slice-specific configurations at different protocol layers, such as adaptive scheduling at the Medium Access Control (MAC) layer and customized numerologies at the physical layer (PHY). Furthermore, ensuring isolation between slices while maintaining overall network efficiency requires sophisticated resource management strategies, including dynamic spectrum allocation and interference mitigation techniques.

Goals of the seminar paper:

• Examine how the resource grid in 5G is structured and allocated among different 5G slices with a possible focus on resource scheduling, isolation mechanisms and strategies for efficient spectrum utilization.

Topic 5: DECT NR+
Supervisor: Simon Egger

DECT NR+ is a non-cellular 5G technology standard that specializes on ultra-high reliability and ultra-low latency (>99.99% reliability at sub-millisecond latencies). This seminar topic aims to provide a technical introduction to the central DECT NR+ mechanisms that enable such guarantees.

 [1] ETSI TS 103 636-1, DECT-2020 New Radio (NR); Part 1: Overview

Goals of the seminar paper:

• Motivate the usage of DECT NR+ compared to public/private 5G deployments.
• Provide a technical introduction to DECT NR+, including its physical layer and media access control (MAC) layer.
• Discuss potential applications and technical limitations of DECT NR+.

Topic 6: Highly-Available Control Planes in Software-Defined Networking
Supervisor: Simon Egger

Software-Defined Networking (SDN) enables dynamic network management and network programmability by decoupling the network control and data plane. This is achieved through a network controller that can provide both low-level control (e.g., adding/removing a switch) and high-level control (e.g., load-balancing) over the network. While logically centralized, modern SDN controllers often follow an microservice-based design (e.g., Google's Orion [1]) that splits the controller independent modules for routing decisions.

Goals of the seminar paper:

• Investigate the design choices of the Orion architecture.
• Provide a technical introduction into consistency models [2] and their necessity when updating the network configuration at runtime.
• Provide an overview of recent approaches on formally verified high-availability control planes [3].

Concurrency

Topic 7: Memory Ordering in the C++ Standard
Supervisor: Simon König

Controlling access to memory plays a crucial role when building concurrent programs. Programmers often assume the operations of their programs to be executed sequentially and in-order. However, optimizations applied by the compiler, the CPU pipeline and the memory management unit can cause the operations of a program to be executed out-of-order. In multi-threaded applications, this has the potential to change the semantics of the program, resulting in unexpected observed behavior. Therefore, synchronization is necessary. The usage of memory barriers allows OS-level primitives (e.g., semaphores) or lock-free data structures to provide meaningful consistency guarantees.

Goals of the seminar paper:

• Investigate the usage and semantics of memory barriers in modern memory models such as the C++ memory model.
• Focus on the theoretical model behind acquire-release or sequentially consistent memory ordering as defined by the C++ standard.

Topic 8: Working with C++20 Coroutines

Supervisor: Simon König

Coroutines, a language feature introduced in C++20, enable efficient asynchronous programming through suspension and resumption of functions.

Goals of the seminar paper:

• Compare state-of-the-art implementations of coroutine frameworks.
• Explore how the C++ compiler translates coroutine functions into state machines that handle suspension points and resumptions.
• Discuss how the compiler constructs and manages promise objects, suspend points, and awaiter types, and how these elements are tightly integrated into the coroutine’s state and execution flow.
• Highlight how the compiler generates the necessary control flow for handling coroutine suspension and resumption without blocking other tasks. This includes the transformation of coroutine functions into a form where control is explicitly passed between the suspended and resumed states, as well as the compiler’s handling of memory management, object lifetimes, and exception propagation in such a framework.

Topic 9: Coroutines - A new form of Subroutines
Supervisor: Lukas Epple

Subroutines encapsulate some computation and help to break down a large program into smaller parts. Coroutines imitate this property, but the lifetime of a coroutine is not tied to the control flow of the program. When a subroutine returns to the calling program, its control information and local variables are destroyed. In contrast, when a coroutine returns control to its caller, its execution is not finished and thus its state is preserved. Each time control reenters the coroutine, it resumes execution where its local control left off and data state is retained. Hence, coroutines are a form of retentive control.

Coroutines are especially well suited for the implementation of asynchronous or event-driven applications. With the use of coroutines, data or IO stalls can be hidden, improving parallelism at runtime and reducing programming complexity at build-time. For this reason, coroutines are experiencing a resurgence. Many popular languages have recently introduced native support for coroutines. Moreover, coroutine-based implementations of highly parallel applications are becoming more and more popular.

Goals of the seminar paper:

• Comprehensive review of relevant literature and case studies on the principles and mechanisms of coroutines, including synchronization primitives for coroutines, state and context switch mechanics for coroutines, and mechanisms for runtime optimization.

Distributed Computing

Topic 10: Utreexo
Supervisor: Lukas Epple

Utreexo offers a pathway to minimize Bitcoin’s Unspent Transaction Output (UTXO) set storage through the use of cryptographic accumulators. This enables the operation of lightweight, fully validating nodes using only a few kilobytes per node while maintaining network security and integrity.

Goals of the seminar paper:

• Explore the internal workings of Utreexo and its potential to improve scalability by examining the impact of Utreexo on node management, decentralization.
• Discuss the future prospects of blockchain technology and potential for participation in the Bitcoin network.

Topic 11: Federated Learning for the Edge
Supervisor: Michael Schramm

Federated Learning is a machine learning setting, where many clients train together without making the data itself accessible for the collaborators. This enables many institutions with smaller datasets to gain insights they couldn’t get with just their own data. Also, in privacy restricted areas like medical data Federated Learning could help.

With the evolving mobile communication technologies edge computing theory and techniques have been attracted an increasing interest of researchers and engineers around the world. Edge computing can help to accelerate content delivery and reduce network load, by communicating with near edge nodes instead of the cloud. This leads to new problems like task scheduling, data replication and data placement.

Goals of the seminar paper:

• Describe challenges for Federated Learning especially in edge networks.
• Explain how some Federated Learning approaches tackle these challenges.
• Compare the results of approaches that take these challenges into account with results of standard Federated Learning approaches.

Topic 12: AI for the Edge
Supervisor: Michael Schramm

With the evolving mobile communication technologies edge computing theory and techniques have been attracted an increasing interest of researchers and engineers around the world. Edge computing can help to accelerate content delivery and reduce network load, by communicating with near edge nodes instead of the cloud.

Artificial Intelligence (AI) is increasingly used to enhance the performance, scalability, and efficiency of edge computing environments. AI-driven techniques help in dynamic resource allocation, predictive maintenance and real-time workload distribution. By leveraging machine learning and deep learning models, edge networks can self-optimize, adapt to changing conditions, and reduce operational costs.

Goals of the seminar paper:

• Describe approaches which use AI to optimize edge computing environments.
• Discuss the benefits and limitations of AI-driven edge optimization.
• Examine the trade-offs between computational overhead and performance gains.

IoT

Topic 13: Matter as an Interoperability Standard for Smart Home Systems
Supervisor: Justin Schiel

Smart home environments typically consist of devices from different manufacturers that must communicate and operate within a shared ecosystem. However, many existing smart home solutions rely on proprietary protocols and platforms, leading to fragmentation and limited interoperability between devices. To address this challenge, the Matter standard has been introduced as a unified application-layer protocol designed to enable reliable and secure communication across devices from different vendors. By providing a common framework for device discovery, communication, and control, Matter aims to simplify the development and integration of smart home technologies.

Goals of the seminar paper:

• Comprehensive review of relevant technical documentation and research literature on the design and functionality of the Matter smart home standard.
• Describe the architecture of Matter, including its interaction with underlying network technologies such as IP-based communication, as well as its mechanisms for device discovery, commissioning, and secure communication. Give particular attention to how Matter enables interoperability between devices and ecosystems from different manufacturers.
• Explain how Matter-based systems operate in practice.
• Discuss the advantages and limitations of Matter systems in terms of interoperability, scalability, security, and its usability in smart home environments.

Topic 14: Thread Protocol and Mesh Networking in Smart Home Systems
Supervisor: Justin Schiel

As the number of connected devices in smart homes continues to grow, communication technologies must support reliable, scalable, and energy-efficient networking. Mesh networking protocols are particularly well suited for this because they allow devices to relay messages through intermediate nodes, thereby extending network coverage and improving resilience. Thread is a relatively recent networking protocol designed for IoT applications that builds upon IPv6. It aims to provide secure and robust mesh communication for smart home devices.

Goals of the seminar paper:

• Comprehensive review of technical documentation and relevant research literature on the design and operation of the Thread networking protocol.
• Describe the different roles of devices in a Thread network, including routers, router-eligible devices, and end devices and explain how the devices collaborate to form a self-healing mesh network.
• Explain how Thread enables reliable communication in distributed IoT systems. Place particular emphasis on the mechanisms used for device discovery, network formation, and message routing between nodes.
• Discuss the advantages and limitations of Thread compared to other mesh networking technologies.

Topic 15: Interdisciplinary Requirements Engineering
Supervisor: Sonja Klingert

Traditionally, requirements engineering has a tendency to create use cases and elicit functional and non-functional requirements with limited user involvement. Often, developers act as representatives for users. Sometimes users’ attitudes are integrated through a small number of interviews. In many cases, this involvement is sufficient, especially when it comes to functional requirements.

However, more and more software systems are being developed where the benefit for users is not directly apparent or where the large number and heterogeneity of users does not allow for a straightforward requirements elicitation. To deal with such complex requirements engineering tasks, an interdisciplinary approach has been suggested, specifically building on findings from psychology and sociology.

Goals of the seminar paper:

• Give an overview of research on integrating users’ feedback into the requirements engineering process using interdisciplinary methods.
• Create a topology of software system problems and corresponding requirements engineering methods.

Topic 16: Contextual Influences in Implicit Gaze Authentication
Supervisor: Melanie Heck

By tracking users’ eye movements while they are performing their daily tasks, their identity can be continuously verified in the background. This provides an additional layer of security without disrupting the user’s current task. However, the reliability of the authentication strongly depends on contextual factors, including multisource ambient lighting, head movements, and the quality (accuracy, sampling rate) of the eye tracking device. While authentication has reached robustness when using high-quality commercial eye trackers, its application in the wild with less powerful devices or even using web cameras remains uncertain.

Goals of the seminar paper:

• Comprehensive review of studies that compare how the performance of gaze-based authentication varies based on the used eye tracking device, ambient conditions, and other contextual factors.
• Extraction of factors that have the highest impact on the authentication performance.
• Discussion of the implications that the identified performance differences have on gaze feature extraction methods and authentication algorithms.

Connected Vehicles

Topic 17: Architectural Patterns for Self-Organizing Train Coordination with MAPE
Supervisor: Melanie Heck

Traditional railway signaling relies on centralized control, but more flexible, self-adaptive architectures hold the potential to improve reliability and compliance with schedules. The MAPE-K framework enables self-adaptation by assigning the tasks of Monitoring, Analysis, Planning, and Execution to distinct components. A range of architectural patterns with varying degrees of decentralization and physical distribution of the MAPE components are currently deployed in volatile mobile scenarios, such as coordinated robot fleets and vehicular platooning.

Goals of the seminar paper:

• Comprehensive overview of scientific literature on MAPE patterns in mobile scenarios, focusing on the spectrum of decentralization and distribution.
• Discuss how varying degrees of distribution—ranging from localized MAPE loops on individual units to hierarchical structures—address the trade-offs between local autonomy and global system stability.
• Identify adaptation actions that are performed in the reviewed scenarios

Topic 18: Vehicle to Everything (V2X) Communication Testing
Supervisor: Sven Feyerabend

As the automotive industry transitions toward Cooperative, Connected, and Automated Mobility, Vehicle-to-Everything (V2X) communication has emerged as a critical enabler. V2X describes a highly dynamic distributed system where vehicles, infrastructure, and vulnerable road users communicate to enable advanced functionalities like intersection assistance.

However, the safety-critical nature of these distributed functions poses a massive challenge for verification and validation. Testing V2X systems is non-trivial due to the sheer infinite number of traffic scenarios and the non-deterministic behavior of wireless communication channels (e.g., C-V2X or ITS-G5). A multitude of methodologies have therefore emerged to ensure the reliability of V2X functions.

Goals of the seminar paper:

• Communication Technologies & Standards: Analyze the underlying physical and networking layers (e.g., ITS-G5 vs. C-V2X). How is seamless communication realized in a decentralized topology and what standards govern these protocols?
• Simulation Testing: Evaluate the current simulation landscape. What frameworks (e.g., OMNeT++, SUMO, CARLA) allow for the co-simulation of network traffic and vehicle physics to validate distributed V2X components?
• Real-World Deployment & Field Trials: Review prominent pilot projects and testbeds. What are the lessons learned from large-scale real-world deployments regarding signal interference, latency bounds, and system scalability?

Topic 19: The Role of Open Source Software in CAV and V2X Research
Supervisor: Sven Feyerabend

Connected Automated Vehicles (CAV) combine automated driving functions with network connectivity (Vehicle-to-Everything, V2X) to leverage off-board information for safer and more efficient transportation. While manufacturers largely rely on proprietary software stacks, open-source software for automated driving has matured considerably in recent years. A prominent example is Autoware, a comprehensive open software stack for automated driving. It leverages the Robot Operating System 2 (ROS2) as a communication middleware, which allows for seamless integration with other projects, such as the open-source autonomous driving simulator CARLA. Furthermore, both Autoware and CARLA support functionality related to Vehicle-to-Everything (V2X) communication, often facilitated through specific open-source plugins.

But how do these underlying frameworks operate, and how are they actively applied in current research? What capabilities do they offer researchers investigating cooperative driving?

Goals of the seminar paper:

• Technical Foundations: How does ROS2 enable communication, and what makes it suitable for automated driving?
• Existing Software: What are the existing research approaches and software solutions that leverage Autoware as a foundation to investigate CAV and V2X?
• Simulators: How are simulators like CARLA integrated with Autoware to test and validate V2X functionalities? Give an overview of the capabilities for V2X communication of the simulator.

Topic 20: Vehicle-to-Everything (V2X) Communication: Market Adoption Hurdles and Regulatory Constraints
Supervisor: Julian Siebert

Vehicle-to-Everything (V2X) communication promises tremendous opportunities for future mobility. It enables vehicles (cars, buses, trucks, etc.) to exchange information directly with their surroundings—including other traffic, infrastructure, and vulnerable road users like pedestrians. As the crucial backbone of Intelligent Transport Systems (ITS), this connectivity enhances everyday efficiency and paves the way for fully automated driving through use cases like non-line-of-sight sensing and cooperative maneuvers.

While the underlying technologies and communication protocols (like those standardized by ETSI) have been available for years, widespread market adoption remains limited. Manufacturers like Volkswagen have begun integrating selected V2X features into their vehicles, but a recent interview study identified regulatory hurdles as a primary reason stalling broader deployment.

Goals of the seminar paper:

• Provide a brief overview of existing V2X standards and protocols.
• Identify and describe regulatory conditions, contrasting developments across multiple markets.
• Analyze the broader reasons for the current lack of widespread market adoption of V2X functionality.

Topic 21: ROS 2 in Modern Robotics: Architecture and Middleware
Supervisor: Julian Siebert

The Robot Operating System 2 (ROS 2) has established itself as the de facto standard for developing complex robotic applications. As robots evolve from isolated machines to highly interconnected, distributed systems – involving numerous sensors, actuators, and processing units – the need for robust, real-time communication between these components is paramount.

At its core, ROS 2 functions as a powerful middleware layer that sits between the host operating system and the robotic application code. By leveraging the industry-standard Data Distribution Service (DDS), ROS 2 abstracts underlying hardware and network complexities, providing a modular, secure, and highly scalable communication framework. Understanding how this middleware routes data and manages node-to-node connectivity is crucial for designing reliable robotic systems that require deterministic, low-latency data exchange.

Goals of the seminar paper:

• Provide an architectural overview of ROS 2 and its underlying integration with the Data Distribution Service (DDS).
• Analyze the core middleware communication paradigms, including Publish/Subscribe, Client/Service, and Actions.
• Evaluate the role of Quality of Service (QoS) profiles in managing real-time data constraints, network reliability, and distributed system performance.

Melanie Heck