HIT SEIE Academic Activities : Invited Talk by Prof. Tad Matsumoto

Harbin Institute of Technology Advanced Communications Technologies Forum 2018

Title 1: Introduction to Frequency Domain Turbo Equalization and its Applications

Date and Time: 9:00-11:30, September 22, 2018




The goal of this lecture is to provide the audience with understanding of “turbo principle”.  To achieve this goal, this lecture will be started with the sliding window soft cancellation minimum mean squared error filtering (SC-MMSE) turbo equalization for single carrier signal transmission over frequency selective fading channels with relatively short memory. Then, this lecture introduces time-domain block-wise processing, and shows that no gains achieved by making modifications from sliding window to block wise processing due to its intractably heavy computational complexity.  Plus, this lecture further modifies the time-domain block wise SC-MMSE turbo equalization to frequency domain (FD SC-MMSE), where it is shown that the required computational complexity is very light and is constant regardless of the channel memory length.

Also, this lecture provides introductory explanations to the extrinsic information transfer (EXIT) chart as a tool for evaluating the efficiency of mutual information exchange. Information theoretic convergence analysis of the FD-SC MMSE turbo equalization, exemplifying the turbo principle, are provided in this lecture Furthermore, the concept of the FD SC-MMSE turbo equalization is applied to multiple input multiple output (MIMO) systems as a reasonable extension of the technique.  It is shown that when analyzing the mutual information exchange for MIMO turbo equalization, multi-dimensional EXIT plane has to be used.  Finally, trends and future prospects of research work towards broadband mobile communication systems are introduced, including turbo equalization of orthogonal frequency division multiplexing (OFDM) and single carrier (SC)-FDMA as well as the technique for eliminating the cyclic prefix (CP) from block-wise processing based FD SC-MMSE turbo equalization.


Title 2: Turbo Equalization and its Information Theoretic Analysis

Date and Time: 18:00-20:30, September 25, 2018




A goal of this talk is to provide audience with the knowledge about the relationship between relay systems and the Distributed Coding techniques for correlated sources. To achieve this goal, this lecture is started by the re-enforcement of understanding of turbo principle, especially, frequency-domain soft cancellation minimum mean square error (FD SC-MMSE) based multiple-input multiple-output (MIMO) turbo equalization (This part is provided in Lecture-1). This lecture uses a lot of multi-dimensional extrinsic information transfer (EXIT) analysis to reveal the convergence properties of the FD SC-MMSE MIMO equalization, and identifies the optimal, close capacity achieving structure. It is shown that even with very simple serially concatenated convolution code with the component codes being very simple memory one codes can achieve near-capacity performance. Furthermore, the inner code, which is a very simple memory one recursive code, can eliminate the error floor due to the intersection of the EXIT curves, resulting in very sharp shape of the turbo cliff. This lecture also makes comparison of the shape of the EXIT curves with recursive and non-recursive convolutional codes.

At the final part of this lecture, we intentional “add” binary errors randomly between the MIMO antennas, and analyses the impacts of the “artificial errors”. It is shown that if the FD SC MMSE equalizer can utilize the error probability to modify the log likelihood ratio (LLR) in the vertical iteration, we can eliminate the effect of the “artificial errors”. The “artificial error” probability can be estimated only at the decoder side (no side information needed).

Obviously the “artificial errors” inserted in the connections between the antennas correspond to the “intra-link” errors in distributed lossy forwarding cooperative networks. Therefore, the last part of this lecture is a preparation of Lecture 3, Tutorial on Lossy Forward Relaying: Orthogonal and non-Orthogonal cases.


Prof. Matsumoto received his bachelor’s and master’s degrees in electrical engineering from Keio University in Japan in 1978 and 1980, and his Ph.D. in 1991. He has taught at York University in Canada, Ilmenau University of Technology, Germany, and Keio University in Japan. Since April 2002, Prof. Matsumoto has taught at the University of Oulu, Finland. He has taught MIMO communication technology and turbo code principles and applications. Since 2007, he has also taught at the University of Japan’s Hokuriku Science and Technology University. , teaching two courses of information theory and coding theory.

Prof. Matsumoto’s research direction is mainly information theory and coding, especially the coding and equalization techniques of turbo codes. Prof. Matsumoto has been involved in the field of turbo code for more than 15 years. In 2004, he discussed the application of turbo code correlation technology to receivers for wireless communication, and then discussed extending the application of turbo codes to performance analysis in communication scenarios such as multi-antenna. The above research is included in Mobile Broadband Multimedia. In Networks Techniques, Models and Tools for 4G.

Prof. Matsumoto also studied the communication performance improvement of the iterative process for cooperative communication methods, and has published articles in a large number of well-known journals. In addition, he has served as an editor of several international academic journals. Prof. Matsumoto has received IEEE Outstanding Contribution Award, IEICE Best Paper, IEEE Outstanding Review, IEEE Distinguished Speaker, Finnish Distinguished Professor and other awards and titles since 2002. . At the same time, he is also IEEE Fellow, which has a great influence in the field of communication.


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