 An IBM researcher since 1960, Rissanen received his Ph.D. from the Helsinki University of Technology in 1965.Retired from IBM, he is now professor emeritus of Tampere University of Technology and a fellow of Helsinki Institute for Information Technology.He was awarded the IEEE Richard W. Hamming Medal in 1993, an IEEE Golden Jubilee Award for Technological Innovation from the IEEE Information Theory Society in 1998, the Kolmogorov Medal of the University of London in 2006, and the IEEE Claude E. Shannon Award in 2009.