1. Faculty of Transport and Computer Science, WSEI University, 20-209 Lublin, Poland
2. Netrix S.A., Research & Development Centre, 20-704 Lublin, Poland
3. Faculty of Management, Lublin University of Technology, 20-618 Lublin, Poland
4. Department of Applied Mathematics, Lublin University of Technology, 20-618 Lublin, Poland
5. Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY, UK