Martina Zitterbart

Mobile ad hoc networks - current approaches and future directions

Most research efforts in the area of MANETs focus on developing efficient routing protocols. Although routing protocols assume unique node addresses, the question of how to provide them remains open. In order to allow truly spontaneous and infrastructureless networking, a protocol for dynamic allocation of unique addresses is needed. Recently, various address autoconfiguration protocols for MANETs have been proposed. This article gives an overview of the challenges of address autoconfiguration in MANETs, presents current approaches, and discusses their advantages and drawbacks.

A model for flexible high-performance communication subsystems

A function-based communication model that allows applications to request individually tailored services from the communication subsystem is presented. Based on service requirements and available resources, suitable protocol machines are configured to serve the application. This configuration is done using a proper combination of functional modules. The concept of layering is therefore abandoned for both flexibility and efficiency reasons. >

High-speed transport components

An overview of research of high-speed transport components is given. High-speed protocols as well as high-speed implementations are considered. The use of parallelism to increase the performance of communication nodes is considered. A parallel implementation of Open Systems Interconnection (OSI) protocols on transputer networks based on the parallel concepts discussed is described. Selected performance values of the implementations are presented. The outlook on the design of high-speed transport components for future communication systems is examined.<<ETX>>

Introducing probabilistic radio propagation models in OMNeT++ mobility framework and cross validation check with NS-2

When performing wireless network simulations, the lack of precise channel modeling in simulator frameworks becomes a serious problem. Often deterministic models are used for packet propagation, which describe real conditions insufficiently. To close this gap we extended the OMNeT++ Mobility Framework to support probabilistic propagation models. We provide an implementation for the Log-Normal-Shadowing, Nakagami, Rayleigh and Rice wave propagation models and set up a framework that allows easy integration of additional models in future. Due to the characteristics of probabilistic radio models a fixed maximum packet propagation range encounters the problem of inaccurate simulation results as relevant events may be suppressed. On the other hand, unlimited packet propagation, which guarantees for correct simulation runs, causes unnecessary simulation overhead. In this work we present an approach to limit the event delivery to the area where the probability that the event is relevant to the simulation exceeds an adjustable threshold. In order to validate our extensions we successfully performed a detailed crosscheck with the network simulator NS-2 and run a performance evaluation and comparison.

Subjective quality assessment for multiplayer real-time games

Mean Opinion Score (MOS) tests are a well-known procedure to indicate the suitability of telecommunications equipment to provide voice services. However, converged data networks provide a variety of services, increasingly entertainment services as e.g. games. After describing the potential of games for Third Generation (3G) mobile networks, this paper establishes first guidelines to perform subjective assessment of game quality. Subsequently, an experimental study is conducted to assess the game quality of a multiplayer real-time game, XBlast, for different network conditions.

A Node Architecture for 1000 Future Networks

One possible key technology for the future Internet is network virtualization. It allows to run numerous virtual networks in parallel, each of which can be adapted towards different requirements, intended use, or applications used. When consequently using network virtualization, it allows not only to have very specialized networks but also allows to run new protocols and services in different networks. This can give opportunities for rapid service deployment, especially for services based on new protocols. Currently a lot of research is concerned with network virtualization or related aspects like management or signaling of network virtualization. This paper however is different, since it looks on network virtualization from another angle. We describe our Node Architecture for the Future Internet, which uses network virtualization as a fundamental concept. It has the goal to give users access to a vast number of virtual networks and exploit the possibilities of network virtualization.

Quality-of-service signaling for next-generation IP-based mobile networks

We present a novel end-to-end QoS architecture that enables seamless services over heterogeneous wireless access networks. We discuss the main architectural approaches and design issues of mobility-aware QoS signaling in IP networks. Then we introduce a QoS signaling architecture that integrates resource management with mobility management. It is based on a domain resource manager concept and nicely supports various handover types in an integrated approach. In particular, we support anticipated handover with pre-reservation of resources over the old network before the mobile node is attached to the new access point.

A wireless sensor network for border surveillance

We will demonstrate a wireless sensor network system for the surveillance of critical areas and properties -- e.g. borders. The system consists of up to 10 sensor nodes that monitor a small border area. The protocols we show focus on detecting trespassers across a predefined area and reporting the detection to a gateway node securely. There, the trespassers path will be graphically diplayed on a border map. The demonstration features secure protocols for the detection of trespassers, node failure and network partitioning, along with a duty cycle protocol to ensure network longevity. All information pertaining to relevant events in the network or border area will be graphically displayed on a gateway computer.

An efficient key establishment scheme for secure aggregating sensor networks

Key establishment is a fundamental prerequisite for secure communication in wireless sensor networks. A new node joining the network needs to efficiently and autonomously set up secret keys with his communication partners without the use of a central infrastructure. Most cited current research papers focus on a probabilistic distribution of sets of keys from larger key pools to new nodes. This results in unnecessary expensive communication and memory consumption, growing linearly with the size of the network, and guarantees secure connections only with a certain probability. This work presents a novel approach for efficient and secure key establishment of nodes joining the network by utilizing the fact that communication in sensor networks follows a paradigm called aggregation. Keys are split into shares and forwarded using disjoint paths in the network. The approach is self-organizing and minimizes memory consumption as well as radio transmissions efficiently -- down to logarithmic behavior.

A flexible framework for Future Internet design, assessment, and operation

Many clean-slate approaches for Future Internet architectures aim at replacing the current architecture with just a single new architecture. Network virtualization, however, paves the way for the concurrent support of multiple network architectures. With todays diversity of networked applications, supporting many specialized architectures is a more future-proof solution. Therefore, we propose a flexible framework for the design and development of new architectures and their concurrent operation. In addition, we provide means for assessing competing protocol implementations and for selecting the most suited one for a particular communication task, based on the requirements imposed by applications and users.