讲学题目1: Introduction to Frequency Domain Turbo Equalization and its Applications
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.
讲学题目2: Turbo Equalization and its Information Theoretic Analysis
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.
讲学题目3: Tutorial on Lossy Forward Relaying: Orthogonal and non-Orthogonal cases
A goal of this lecture is to provide audience with the knowledge about the relationship between relay systems and the Distributed Coding techniques for correlated sources. The focus of this lecture is on cooperative communications. It is shown that performance of the conventional decode-and-forward system can significantly be improved by performing another interleaving at the relay, with which the resulting network structure is equivalent to distributed turbo code. Furthermore, since the knowledge about the bit error probability of the source-relay node can be used as the correlation between the two frames, one from the source, and the other from the relay, we can well exploit the Slepian-Wolf theorem; With the utilization of the theorem, the relay can forward the frame even though it detects errors in the information part, and the destination can recover the data losslessly.
This lecture introduces conceptual bases of the lossless (Slepian Wolf) multi-terminal network design, and provides performance bounds as well as basic ideas for signal detection algorithms based on the turbo principle. Results of initial simulations conducted to evaluate the performances of the detection/decoding techniques for several simple network models are also presented for the both orthogonal and non-orthogonal signaling cases. The major applications of the system concept introduced in this keynote speech are Wireless Mesh Networks, Wireless Sensor Networks, Wireless Machine-to-Machine networks, Wireless Internet-of-Things, and Densely Populated Wireless Networks, as well as Rapid Construction of Monitoring Systems in Devastated Public Facilities, such as Fukushima.
Then, this lecture further expands the idea, from lossless-link-design-based to lossy-based. In this part, we assume that none of the relays at the final stage has no errors in the information parts of the frames. This category of the problems belongs to Distributed Lossy Coding, represented by the Chief Executive Officer (CEO) problem, in Network Information Theory. Even in this situation, still the destination can recover the data with the distortion level lower than specified. For this purpose, Rate-Distortion bounds are introduced to the binary CEO problem.
Finally, this talk briefly introduces "Links-on-the-fly Technology for Robust, Efficient and Smart Communication in Unpredictable Environments (RESCUE) a EU FP7 ICT-2013 project, of which concept was motivated by the technological bases described above. The objective of the project is to create energy- and spectrally-efficient communication systems which are robust against unpredictable network topology changes. The origin of the project proposal is that massive earthquakes including series of aftershock hit the Tohoku and Kanto areas in Japan on March 11, 2011, followed by unprecedentedly huge Tsunami waves of up to 40 m height. After the huge devastative/disastrous event clearly indicated several limitations in operability of the conventional wireless communication systems based on the accurate link budget allocation concept and communication chain design (coding, signaling chain, as well as also higher layer protocols), and the continuation of the communication is supported by a proper handover algorithm. The systems, which are expected to keep its operability in unpredicted network damages, have to be robust against the network topology change.
松本教授的研究方向主要是信息论与编码，尤其是turbo码的编码和均衡技术。松本教授已从事turbo码的相关领域研究超过15年。2004年他便讨论了将turbo码相关技术应用于无线通信的接收机中，并随后讨论将turbo码的应用扩展到诸如多天线等通信场景中进行性能分析，以上研究内容收录于《Mobile Broadband Multimedia Networks Techniques, Models and Tools for 4G》一书中。