Telecommunication systems

The basic research activity in Telecommunication systems research group concerns the design, simulation and testing of mobile telecommunication systems and services. Other research activities embrace the development of testing and simulation software tools, provision of security services in communication networks and the development of distributed environments for computer supported co-operative work. The objective of the research work is not only to strengthen the scientific and technological base in the research group but also to transfer the knowledge and new technologies to industry. During the year 1999 we studied the performance of various mobile systems in the radio channel. Several signal distortions due to non-linear channel, Gaussian noise, Rayleigh fading, co-channel interference and Doppler frequency shift were taken into account. Besides GMSK and ?/4-QPSK signals we analyzed also multi-level constant and variable bit rate CPFSK and QAM signals. In order to analyze the applicability of different routing algorithms and to evaluate the performance of new algorithms designed for satellite networks, we have built a simulation model of satellite communication system with inter-satellite links. The result of the Copernicus 708 project was a mobile communication system demonstrator, realized by the DSP development system TMS320C44, the ALTERA programmable circuits and the chip set available on the market. The call set up and call release procedures were specified by the SDL development tool. We have also contributed to the Slovenian Health Insurance Card project and Copernicus NETLINK-CEE project by analyzing and evaluating the interoperability and security issues proposed by the Health Insurance Institute of Slovenia. Continuing our work on formal systems development, we have designed algorithms for automated synthesis of distributed servers based on specifications written in LOTOS and its extensions. We have contributed to the design of the E-LOTOS specification language. We continued our work on the automation of telecommunication services testing. A tool for automated derivation of TTCN test scenarios from SDL specifications describing the required external behavior of services has been developed for IskraTEL. We were concerned also with the problems of multimedia communications and with the development of environments for computer supported distance collaboration.