Wolfgang Kellerer's research while affiliated with Technische Universität München and other places

Publications (267)

Preprint
In this paper, we outline the approach for the derivation of the length of the collision resolution interval for d-ary tree algorithms (TA) with gated access and successive interference cancellation (SIC), conditioned on the number of the contending users. This is the basic performance parameter for TA with gated access. We identify the deficiencie...
Preprint
Ubiquity in network coverage is one of the main features of 5G and is expected to be extended to the computing domain in 6G. In order to provide this holistic approach of ubiquity in communication and computation, an integration of satellite, aerial and terrestrial networks is foreseen. In particular, the rising amount of applications such as In-Fl...
Preprint
While 5G delivers high quality services mostly in a two dimensional terrestrial area covering our planet's surface, with 6G we aim at a full exploitation of three dimensions. In this way, 6G includes all kinds of non-terrestrial networks. In particular, Unmanned Aerial Vehicles (UAVs), High-Altitude Platforms (HAPs), (self-)flying taxis and civil a...
Technical Report
Full-text available
The ubiquitous spread of programmable data planes has been conditioned by the development and use of domain specific languages. One such very convenient programming language is P4, which enables devices, like switches, to be configurable and protocol-independent, making it a perfect match for Software Defined Networks. Therefore, analyzing the metr...
Conference Paper
Full-text available
The adoption of the cloud-native paradigm in mobile core networks has introduced increased traffic in the control-plane stemming from the inter-Network Function (NF) communication. In this paper, we evaluate a different functional (de)composition for the 5G Core NFs with the goal of achieving high performance and efficient orchestration while reduc...
Preprint
Full-text available
This is the PREVIEW version of a paper about 6G. This paper is a summary of the findings from a series of workshops which were held by Thinknet 6G and MUENCHNER KREIS in 2021, with the goal to provide orientation and input for developing a strategic 6G research plan. The topics selected for the workshops are aspects of 6G that we expect will have a...
Preprint
Networked control systems (NCSs) are feedback control loops that are closed over a communication network. Emerging applications, such as telerobotics, drones and autonomous driving are the most prominent examples of such systems. Regular and timely information sharing between the components of NCSs is essential, as stale information can lead to per...
Preprint
In this work, we consider a remote monitoring scenario in which multiple sensors share a wireless channel to deliver their status updates to a process monitor via an access point (AP). Moreover, we consider that the sensors randomly arrive and depart from the network as they become active and inactive. The goal of the sensors is to devise a medium...
Preprint
Full-text available
Although 5G (Fifth Generation) mobile technology is still in the rollout phase, research and development of 6G (Sixth Generation) wireless have already begun. This paper is an introduction to 6G wireless networks, covering the main drivers for 6G, some of the expected use cases, some of the technical challenges in 6G, example areas that will requir...
Conference Paper
Full-text available
The recent trend to deploy programmable packet processors in cloud environments enhances the packet processing capability without losing the flexibility to adapt the functions at runtime. However, managing network functions, in particular deciding where to instantiate a certain function, is a non-trivial task with many decisive factors. In this pap...
Conference Paper
Full-text available
The SDN control plane provides the data plane with packet forwarding rules and thus defines its behavior. Understanding the performance of the controller is critical to assess the overall performance of the network. Although OpenFlow-based controllers have been well investigated in this regard, controller performance studies based on P4Runtime, whi...
Article
Full-text available
We study the delay over virtual RAN (vRAN) topologies, entailing base stations that are divided into centralized and distributed units, as well as the packet-switched fronthaul network that connects them. We consider the use of flexible functional split, where the functions that are executed at each of these two entities can be dynamically shifted....
Article
5G radio access network (RAN) slicing envisions a solution to flexibly deploy heterogeneous services as slices sharing the same infrastructure. However, this level of flexibility renders slice isolation challenging, mainly due to the stochastic nature of wireless resources. In the state-of-the-art, RAN slicing algorithm’s efficiency with respect to...
Preprint
In this paper, we perform a thorough analysis of tree-algorithms with multi-packet reception (MPR) and successive interference cancellation (SIC). We first derive the basic performance parameters, which are the expected length of the collision resolution interval and the normalized throughput, conditioned on the number of contending users. We then...
Article
Network programmability also sneaked into the mobile world leading to the emergence of Software-Defined Radio Access Network (SD-RAN) architectures. Interestingly, while only a small number of prototype architectures exist for SD-RAN, their performance evaluations are unfortunately also limited. Recent evaluations are carried out for small network...
Conference Paper
Full-text available
To provide the predictability required by emerging applications, operators typically rely on policing and/or shaping at the edge to ensure that tenants do not use excess bandwidth that was not accounted for. One of the promises of 6G is to deploy applications with strict predictability requirements across subnets and even over the Internet, where p...
Article
In order to deliver the high data rates promised for 5G networks, mobile base stations need to be deployed in dense layouts. This results in increased inter-cell interference, which can be mitigated by leveraging centralized architectures in radio access networks. Nonetheless, centralizing all the processing requires prohibitively high link capacit...
Preprint
Modern stateful web services and distributed SDN controllers rely on log replication to omit data loss in case of fail-stop failures. In single-leader execution, the leader replica is responsible for ordering log updates and the initiation of distributed commits, in order to guarantee log consistency. Network congestions, resource-heavy computation...
Preprint
Full-text available
Interactive applications with automated feedback will largely influence the design of future networked infrastructures. In such applications, status information about an environment of interest is captured and forwarded to a compute node, which analyzes the information and generates a feedback message. Timely processing and forwarding must ensure t...
Article
The Softwarization of networks is enabled by the SDN (Software-Defined Networking), NV (Network Virtualization), and NFV (Network Function Virtualization) paradigms, and offers many advantages for network operators, service providers and data-center providers. Given the strong interest in both industry and academia in the softwarization of telecomm...
Article
Full-text available
Providing predictable performance to tenants is mission critical for network hypervisors. As a hypervisor acts as an intermediary between tenants controllers and the physical infrastructure, its resources (e.g., CPU, RAM) should be provisioned and allocated carefully. Initially, we demonstrate that state-of-the-art CPU prediction approaches are not...
Article
Full-text available
Service function chains (SFCs) are an ordered set of virtual network functions (VNFs) which can realize a specific network service. Enabled by virtualization technologies, these VNFs are hosted on physical machines (PMs), and interconnected by network switches. In today networks, these resources are usually under-utilized and/or over-provisioned, r...
Chapter
Industrial Internet of Things (IIoT) comprises a variety of sensing and actuation applications deployed in automation scenarios. With their stringent latency and reliability requirements and, on the same time, sporadic traffic patterns, IIoT challenges the way radio resources will be managed beyond 5G networks. Conventional grant-based scheduling i...
Article
Full-text available
In the field of networking research, increased flexibility of new system architecture proposals, protocols, or algorithms is often stated to be a competitive advantage over its existing counterparts. However, this advantage is usually claimed only on an argumentative level and neither formally supported nor thoroughly investigated due to the lack o...
Article
Providing scalable user- and application-aware resource allocation for heterogeneous applications sharing an enterprise network is still an unresolved problem. The main challenges are as follows: (i) How do we define user- and application-aware shares of resources? (ii) How do we determine an allocation of shares of network resources to application...
Article
Full-text available
Data plane programmability brings network flexibility to a new level. However, it introduces the complexity of the data path's program as a new factor that influences packet forwarding latency and thus devices' performance. Accurate identification of the relation between data path complexity and packet forwarding latency enables the design and mana...
Article
The recent trend of network softwarization suggests a radical shift in the implementation of traditional network intelligence. In Software Defined Networking (SDN), for instance, the control plane functions of forwarding devices are outsourced to the controller. Softwarized network components are expected to provide uninterrupted service during lon...
Preprint
We consider the distributed resource selection problem in Vehicle-to-vehicle (V2V) communication in the absence of a base station. Each vehicle autonomously selects transmission resources from a pool of shared resources to disseminate Cooperative Awareness Messages (CAMs). This is a consensus problem where each vehicle has to select a unique resour...
Article
Full-text available
Artificial Intelligence (AI) and Machine Learning (ML) approaches have emerged in the networking domain with great expectation. They can be broadly divided into AI/ML techniques for network engineering and management, network designs for AI/ML applications, and system concepts. AI/ML techniques for networking and management improve the way we addre...
Article
Networked control system (NCS) refer to a set of control loops that are closed over a communication network. In this article, the joint operation of control and networking for NCS is investigated wherein the network serves the sensor-to-controller communication links for multiple stochastic linear time-invariant (LTI) sub-systems. The sensors sampl...
Chapter
Network and service disruptions could have several causes ranging from software to hardware failures, due to malicious users and/or weather-related failures. While most of the failures are unpredictable, weather-based disasters such as tornadoes, hurricanes, wildfires or floods can be often predicted well in advance, which leaves enough time for op...
Article
Full-text available
We investigate the problem of semi-decentralized, interference aware scheduling in a cellular network with Device-to-Device (D2D) links. Our goal is an algorithm that allows optimal resource allocation and power control in spite of mutual interference from and to D2D links, as well as the creation of a reporting structure that is independent of the...
Article
In this letter, we propose a short-frame (SF) length approximation for the packet loss rate of Irregular Repetition Slotted Aloha (IRSA) particularly suitable for very short frames up to 50 slots, motivated by low-latency targeting IIoT applications. Our analysis is based on the Error Floor (EF) approximation ef2018. We extend the approximation thr...
Article
Compared to previous mobile generations, the 5G system architecture offers more flexibility to fulfill a richer set of diverse requirements. Three system aspects play a major role here: support of network slicing, a split between the user plane and the control plane, and a service oriented control architecture. Emerging techniques of network softwa...
Preprint
Full-text available
In this paper, we analyze binary-tree algorithms in a setup in which the receiver can perform multi-packet reception (MPR) of up to and including K packets simultaneously. The analysis addresses both traffic-independent performance as well as performance under Poisson arrivals. For the former case, we show that the throughput, when normalized with...
Article
In the context of the 5G ecosystem, the integration between the terrestrial and satellite networks is envisioned as a potential approach to further enhance the network capabilities. In light of this integration, the satellite community is revisiting its role in the next generation 5G networks. Emerging technologies such as Software-Defined Networki...
Preprint
Age of information (AoI) measures information freshness at the receiver. AoI may provide insights into quality of service in communication systems. For this reason, it has been used as a cross-layer metric for wireless communication protocols. In this work, we employ AoI to calculate penalty functions for a centralized resource scheduling problem....
Conference Paper
Full-text available
Adoption of Software-defined Networking (SDN) in critical envi- ronments, such as factory automation, avionics and smart-grid networks, will require in-band control. In such networks, the out- of-band control model, prevalent in data center deployments, is inapplicable due to high wiring costs and installation efforts. Exist- ing designs for seamle...
Article
Age-of-information (AoI) is a metric quantifying information freshness at the receiver. It captures the delay together with packet loss and packet generation rate. However, the existing literature focuses on average or peak AoI and neglects the complete distribution. In this work, we consider a N-hop network with time-invariant packet loss probabil...
Article
With the move from traditional hardware appliance based network functions to Network Function Virtualization, software development is decoupled from the hardware. However, as a network function is no longer optimized for hardware, beneficial features of networking hardware may not be used any more. Solutions such as SDN or NIC offloading aim to ove...
Article
Full-text available
In Software Defined Networking (SDN), network programmability is enabled through a logically centralized control plane. Production networks deploy multiple controllers for scalability and reliability reasons, which in turn rely on distributed consensus protocols to operate in a logically centralized manner. However, bugs in distributed control plan...
Article
Direct communication among user equipments, called Device-to-Device (D2D) communication, is envisioned in academia and industry to enhance future cellular networks for increased spectral efficiency. Mode selection considers the question which links should be offloaded to use direct communication mode and is one of the core questions in D2D research...
Conference Paper
Full-text available
Byzantine Fault Tolerance (BFT) enables correct operation of distributed, i.e., replicated applications in the face of malicious takeover and faulty/buggy individual instances. Recently, BFT designs have gained traction in the context of Software Defined Networking (SDN). In SDN, controller replicas are distributed and their state replicated for hi...
Conference Paper
Full-text available
Today, on-board passengers request Internet-based services, such as video streaming, Voice over IP, etc., at low cost. Many of those services have stringent QoS requirements, e.g., low end-to-end delay. To offer these services efficiently, some problems need to be solved jointly: placement of services (i.e., Virtual Machines (VMs)), at Datacenters...
Preprint
The upcoming industrial revolution requires deployment of critical wireless sensor networks for automation and monitoring purposes. However, the reliability of the wireless communication is rendered unpredictable by mobile elements in the communication environment such as humans or mobile robots which lead to dynamically changing radio environments...
Conference Paper
Full-text available
A predictable network performance is mission critical for many applications and yet hard to provide due to difficulties in modeling the behavior of the increasingly complex network equipment. This paper studies the problem of providing deterministic latency guarantees in small networks based on low-capacity hardware (e.g., in-cabin and industrial n...
Conference Paper
The upcoming industrial revolution requires deployment of critical wireless sensor networks for automation and monitoring purposes. However, the reliability of the wireless communication is rendered unpredictable by mobile elements in the communication environment such as humans or mobile robots which lead to dynamically changing radio environments...