1- Visiting Researcher, Institute of Communications Engineering, Tampere University of Technology, Tampere, Finland, June-July 2006. (Host Prof. Markku Renfors)
2- Visiting Researcher, ARC Special Research Center for Ultra-broadband Information Networks (CUBIN), University of Melbourne, Melbourne, Australia, July-Aug. 2007. (Host Dr. Stephen Hanly)
3- Visiting Researcher, European Institute for the study of RANDOMness (EURANDOM), Eindhoven University of Technology, Eindhoven, Netherlands, Feb. 2008. (Host Prof. Sem Borst)
4- Visiting Researcher, School of Mathematics, University of Bristol, Bristol, UK, July-Aug. 2008. (Host Dr. Ayalvadi Ganesh)