Finalized Projects

The aim of CAROUSAL is to design and implement a cognitive radio prototype with an application in the industry in mind, namely with industrial automation as a main field of application. Shifting from wired to wireless already has countless benefits, and the use of cognition gives a clear edge on the wireless solutions already used in automation, as here, high reliability and low data delivery delay are required. CAROUSAL will achieve this goal by combining optimized time-frequency pulses with a cognitive channel access scheme based on prediction of spectral white spaces to avoid collision. 

The progress in wireless communications achieved over the last few decades has made it possible that today more than half of the world’s population can communicate using wireless and mobile radio systems. Increasingly, broadband information infrastructure can be accessed using advanced communication systems. In the future, however, the provision of different types of services by massively interconnected wireless sensor and communication systems will revolutionize living and working environments. For the so-called ubiquitous communication, i.e. the exchange of information in a network of users, computers and physical objects at any place and any time, the further development of scientific methods and tools, of new basic technologies as well as novel communication paradigms is required urgently.

An independent study of the international consortium "The Climate Group", consisting of representatives from economy, politics and administration, shows that the emissions of CO2 caused by information and communication technology (ICT) devices will double until the year 2020. Simultaneously, however, sensor networks offer substantial improvements of energy efficiency by monitoring and optimization. As a consequence, global emissions of CO2 outside the ICT sector can be saved by about 10 percent. This corresponds to savings of 7.8 billion tons of CO2 per year with respect to the year 2020. Clearly, these savings exceeding the emission of CO2 of the United States or the People’s Republic of China can only be achieved by the further development and future use of ICT.

Apart from the aforementioned energy savings, there are many different novel applications and corresponding scientific problems of communication networks which can be cast into the context of a so-called Smart City. The latter concept requires an intelligent environment in which services supporting the daily life are available always and everywhere. Embedded in a Smart City are intelligent buildings (smart homes), intelligent transportation systems (smart transport), wireless personal area networks (PANs) and wireless and mobile backbones. In order to realize this vision, an infrastructure is required where all devices can communicate with each other wirelessly in a cooperative fashion. In such a network with a huge number of mobile and stationary nodes and the simultaneous consideration of different performance criteria (e.g. the data rate or latency requirements), the following aspects are of utmost importance:

• flexible and scalable network and device architectures

• efficient resource management

• security and context sensitive services with quality orientation

• interference resistant cooperative communications

• energy and bandwidth efficient wireless communications

• reconfigurable transceiver architectures.

In view of the huge number of nodes and the high node density, fundamentally new approaches for satisfying the aforementioned requirements are necessary, e.g. strategies for the interference management, scalable architectures for supporting heterogeneous networks and services as well as implementation approaches for energy efficient and reconfigurable transceiver architectures.

The objective of the project Cooperative Sensor Communication (COCOON) (jointly carried out with the Technical University of Darmstadt in the framework of the LOEWE program) is the establishment of an interdisciplinary research focus which is to address fundamental scientific problems in the area of cooperative sensor communication. To that end, scientific methods and tools for cooperative sensor communication will be developed and implemented in a platform. The starting point is the assumption of a dynamic system of spatially distributed and autonomous sensors representing the nodes of a complex communication network, while no novel sensors or sensor technology will be developed.

This project jointly carried out with the University Hospital in Dusseldorf focuses on the simulation and the experimental verification of radiofrequency ablation used in kidney cancer therapy. A high frequency electric current is introduced into the affected tissue by a special applicator which is placed in the human body. The impact of the electric energy results in a warming of the tissue and leads to a necrosis of the tumor after a certain time. The objective of this work is to build a computer model which considers the changes in tissue properties caused during the ablation process in order to do a preplanning of a corresponding treatment. Different simulation tools are applied. The software package Femlab from Comsol offers the possibility of solving coupled partial differential equations, which occur in this problem. This is the bioheat-equation on the one hand and the equations for the electric and magnetic potentials, describing the electro-magnetic quantities, on the other hand. These equations have to be extended by the Navier-Stokes equations from fluid dynamics to take into account perfusion arising from blood and urine flows within the kidney and leading to a cooling of the target area. The simulation is compared with the results of an appropriate measurement system built in the lab. In order to verify the results in real-world experiments, a sample treatment is carried out with pigs where testing probes measure the temperature over time at different positions in the target tissue.