Ruizhi Chen holds a PhD degree in Geophysics, a MSc. degree in computer science and a BSc. degree in Surveying Engineering. He is Head of the Department of Navigation and Positioning at the Finnish Geodetic Institute and an adjunct Professor in the Department of Computer Systems at Tampere University of Technology. Dr. Chen worked in Nokia as an engineering manager from 1998-2001. He has been involved in research of multi-sensor positioning for mobile devices since 2001. He led a project to develop a 3D personal navigation system in smart phones during 2007-2010. The system was demonstrated at the Shanghai World EXPO in 2010. Dr. Chen is the member of the editor board of the Journal of Global Positioning Systems. He has published more than 110 scientific articles. He is the chair of the IEEE conference Ubiquitous Positioning, Indoor Navigation and Location-Based Service, held every second year. Dr. Chen is also a board member of the Nordic Institute of Navigation. [Editor]