Research

Most Internet protocols and architectures are designed with the implicit assumption that the underlying link layers provide a more or less consistent behavior with respect to latency, bit error rates, and end-to-end connectivity. These assumptions are valid for most parts of today's public Internet infrastructure, but already the introduction of mobility support can break some of these assumptions. Access networks for mobile communications are an example for challenged networks that might exhibit frequent disruptions, varying bandwidth and delays. Another example of challenged networking environments are networks that cannot provide constant but only intermittent connectivity such as sensor networks with power-consumption-constraints and sparse, irregular connectivity. Slow network links and very long distance networks can impose end-to-end delays that require modifications to transport protocols and overall communication architectures in order to use these networks efficiently.

Research work for communication in challended environments includes aspects such as host and network mobility, mobile ad-hoc networking, transport protocol issues but also architectural considerations.

More about DTN research at TZI.

The term multimedia communication refers to different applications based on synchronous cooperation using networking technologies. This includes multiparty conferencing, IP telephony and realtime streaming. Some of the technologies that must be available are currently being subject to standardiziation and see a first significant deployment, such as SIP based IP telephony.

In the past years, I have developed a framework for the development of distributed, component-based systems. This framework is based on the Message Bus (Mbus) and is essentially used in all of our research projects and software developments as a means to coordinate heterogenous application components (running on different platforms and different hosts). In our research group, we have applied this approach to the coordination of multimedia conferencing systems, i.e., endpoints and gateways.

The introduction of digital broadcasting such DVB- or ISDB-based networks provides new potential for scalable mass distribution of multimedia information and arbitrary data to fixed and mobile users. I am looking at specific technologies such as Mobile TV based on Japan's ISDB-T oneseg system and on bearer-independent technologies such as the Internet Media Guide framework for Electronic Service Guide distribution.

More about Multimedia communications research at TZI.