Markus Hager

Implementation and validation of an address resolution mechanism using adaptive routing

In disaster scenarios, communication systems usually consist of heterogeneous nodes and damaged infrastructure. Communication is important for rescue teams and victims as well but a serious problem because normal network systems like wired or mobile radio Internet could be unreliable or simply not available. To deal with these problems, much effort has been spent to mobile ad hoc networks (MANETs) and their specialties. Those networks are usually unsteady and highly mobile. Therefore, classical network services like resolution of names to their regarding local IP addresses is a big challenge. To overcome the problem of name resolution, we introduced a new approach for consistent and efficient name resolution using adaptive routing techniques. In this paper, we present the implementation for a Linux-based platform using the Click Modular Router and the validation of our testbed using the Network Simulator 3.

Secure and QoS-aware communications for smart home services

In this paper, we present the combination of two concepts addressing important aspects for smart home services: a new quality of service concept and a new integrated concept for a smart home security system. We assume that every flat in a house has its own smart device to perform local services and act as an interface for the different sensors and actors inside the flat. These smart computers are interconnected using a plain switched Ethernet infrastructure. All different types of sensors and actors communicate via different types of standards. Based on the classification of each service, we present a solution to prevent congestion situations inside the network. This scheme is not only applicable to the presented scenario, it could also be applied to handle similar problems within classical computer networks and many other fields. These advantages are realized within the affirmation of security of the whole system. All communication channels, all information and user-data and all kinds of access to the system are secured by a comprehensive security architecture.

IP-based access to sensor networks enabled by a transparent proxy server

The protocol of a sensor network is optimized for its application field, but to benefit from these networks it is necessary to make sensor data available for other networks, too. Therefore, this paper deals with the realization of an interconnection between wireless sensor networks and the Internet. For the first realization of the system, a sensor network based on the IEEE 802.15.4 standard and ZigBee was used. The interface for internetworking is realized as a new gateway-based approach using a transparent proxy server offering a web-based service for the user to query or to change the status of a special sensor network node. The concept of the developed system is independent of the sensor network system and can be used for many network types to establish an interface to the Internet and additionally to provide intercommunication between these technologies.

Quality of service concept for smart home services

Our paper proposes a new quality of service concept for smart home services. We assume that every flat in a house has its own smart computer to perform local services and acts as an interface for the different sensors and actors inside the flat. These smart computers are interconnected using a plain switched Ethernet infrastructure. A central server offers shared services for each user and a gateway realizes Internet access. Based on the defined priority of each service, we present a solution to prevent congestion situations inside the network based on a distributed traffic shaping scheme. Furthermore, the proposed system is not only applicable to the smart home services scenario, it could also be applied to handle similar problems within classic computer networks and many other fields.

Vehicular Ad Hoc networks: Multi-hop information dissemination in an urban scenario

Vehicular ad hoc networks (VANET) are, in conjunction with infrastructure-based communication systems, the main part for intelligent transportation systems (ITS). This technology can significantly alter individual mobility by changing the traditional human controlled car to an autonomous vehicle. Studies and simulations already investigated the high potential of ITS with respect to various use cases like collision avoidance or traffic optimization. The critical aspect for these and all other ITS applications is the efficient information exchange between the vehicles. Much effort has been spent on the design of broadcast protocols for a VANET permitting optimal information dissemination under different environmental conditions. We will give a short overview of these broadcast schemes leading us to the decision to develop a modified version. We determine parameters of the proposed message exchange process and verify its performance in an urban scenario with three different events of interests and regions in comparison to a simple broadcast scheme. Our evaluation shows that a single broadcasting scheme can hardly meet all demands of the communication process by balancing between good information dissemination and an efficient usage of the radio resources.

Software-Based Management for Ethernet Networks

An adequate network management is an essential part for each network permitting to keep the network performance at a suitable level. In this paper, we present our work focusing on an Ethernet network which is used as background interconnection technology for a smart home system in large buildings like tenements or an office block. In this case the network is larger and especially the applications are quite heterogeneous as compared to a private smart home system. Therefore, it is hard to supply a fair and quality of service aware network meeting all the demands. This is especially challenging in the case of an Ethernet network because this technology was intended to use it as a transparent connection system without the feature to support hard quality of service. We present how this problem could be solved by a middleware which best meets the special requirement of the mentioned use case. Finally, we discuss possible design improvements of this solution and present the recent Ethernet standards that could help solve this problem in an alternative way.

Latency avoidance by route assumption for reactive routing protocols

Mobile Ad-hoc Networks (MANETs) can be used to enable data transmissions if no communication infrastructure is available. One of the important tasks in such MANETs is the discovery of routes between the nodes. However, as MANET scenarios can be highly dynamic in terms of the number of participating nodes, the speed of the nodes, or the available energy, a lot of work has been spent into adaption of MANETs to such requirements. Therefore, special routing protocols have been developed. One type of such protocols are reactive routing protocols, where routes are only searched on-demand with the drawback of a latency during the route finding process. In this paper, we present our new approach Latency Avoidance by Route Assumption (LARA) based on the Ad-hoc On-Demand Multipath Distance Vector routing protocol to avoid such latency by monitoring routing packets and assuming probable routes based on the gained knowledge.

Recursive layering of Forwarding on Gates and Traffic Engineering Middleware for Ethernet

Quality of Service (QoS) for inter-networks requires a two-tier approach to separate the end-to-end communication from the QoS provisioning within each autonomous system. However, the interaction between both is not standardized. Furthermore, the solutions for both tiers lack either scalability, flexibility, or QoS guarantees. Our paper presents a combination of “Forwarding on Gates” (FoG) as inter-network and “Traffic Engineering Middleware for Ethernet” (TEME) as intra-network techniques. This combination incorporating a recursive layer model separates the layers based on their scope and not on their functionality. This paper proposes a single interface used by all layers. Furthermore, the same interface is used by applications in order to signal their QoS requirements. This design allows supporting QoS in a more consistent way as compared to the ISO/OSI layer model. The paper outlines the proposal theoretically and demonstrates the advantages with an example.

Non-deterministic approach for hypercomplex orthogonal design (NAHOD)

The Alamouti scheme is a well known coding form for providing transmit diversity in wireless communication scenarios and is, for example, used in the 3G standard. The generalization of this technique using quaternions, allowing to use e.g. polarization as another signal attribute for diversity, has been discussed in several publications. However, there is still the open question how to design such coding matrices. In this paper, we present a generalized form of hypercomplex numbers used as basis for our computation allowing to generalize the notation of complex numbers and quaternions. Moreover, we will discuss the structure of generalized orthogonal designs allowing us to realize a non-deterministic approach for generating such code matrices.