美国加州大学戴维斯分校林舒教授将受聘浙江大学客座教授，并于2011年10月31日---11月2日在浙江大学做精彩的系列学术讲座。
讲座题目：Low-Density Parity-Check Codes（低密度奇偶校验码）
讲座1：LDPC Codes: Developments, Constructions, Applications, and Research Directions
2011年10月31日14:00，浙江大学玉泉校区 教三-441
讲座2：A Transform Approach for Construction and Analysis of Quasi-Cyclic LDPC Codes
2011年11月1日14:00，浙江大学玉泉校区 信电系楼215学术厅
讲座3：Trapping Sets of Structured LDPC Codes
2011年11月2日14:00，浙江大学玉泉校区 信电系楼215学术厅
欢迎各位老师和同学参加。
林舒教授简介
林舒教授1959年毕业于国立台湾大学，获得电子工程学学士学位，后于1964年和1965年从美国莱斯大学（Rice University）分别获得电子工程学硕士和博士学位。1965年起，他就职于美国夏威夷大学（University of Hawaii），任电子工程学助理教授，后于1969年成为副教授，于1973年成为教授。1986年，他作为Irma Runyon Chair Professor加入德州农机大学（Texas A&M University）。1987年，他回到夏威夷大学。从1978年到1979年，作为IBM Thomas J. Watson 研究中心的访问科学家从事数据通信系统的差错控制协议的研究工作。1996-1997年，他作为客座讲座教授加盟德国慕尼黑工业大学（Technical University of Munich）。2000-2011年，他任英国兰开斯特大学（Lancaster University）名誉教授。1999年从夏威夷大学退休，现担任加州大学戴维斯分校的兼职教授。
林教授在国际知名的期刊和会议上发表了400余篇论文。他撰写了An Introduction to Error Correcting Codes，并与D. J. Costello合著了Error Control Coding: Fundamentals and Applications，与T. Kasami, T. Fujiwara, and M. Fossorier合著了Trellises and Trellis-Based Decoding Algorithms, 和Channel Codes: Classical and Modern。他现在的研究领域包括：代数编码理论（algebraic coding theory），编码调制（coded modulation）,差错控制系统（error control systems），卫星通信（satellite communications）以及存储系统编码（coding for storage systems）。他作为首席科学家承担了美国国家自然科学基金、NASA和私营通信企业的43个研究项目。
林教授曾于1976年到1978年担任IEEE TRANSACTIONS ON INFORMATION THEORY代数编码理论的副主编，这是第一次由华裔美国人担任此职务。他曾担任1988年日本神户IEEE International Symposium of Information Theory （ISIT）联合主席，1988年北京IEEE Information Theory Workshop联合主席和2007年成都IEEE Information Theory Workshop联合主席。他曾于1991年任IEEE信息论学会主席，这是第一次也是迄今唯一一次由华裔学者担任此职。
林教授1980年被选举为IEEE Fellow，并于2000年被选为IEEE Life Fellow。1996年，他荣获美国高级科学家Alexander von Humboldt Research Prize。2000年，他荣获IEEE第三千禧年奖章。2007年，他荣获通信学会通信理论领域的Stephen O. Rice Prize。
林教授被誉为世界最顶级的编码理论家和实用家。他与Costello合著的Error Control Coding: Fundamentals and Applications被全世界的实用通信工程师誉为“编码圣经”。他设计或发明的许多编码和差错编码方案曾经或者正在作为通信系统的标准而使用。
讲座摘要
讲座1：LDPC: Developments, Constructions, Applications, and Research Directions
Abstract：The rapid dominance of low-density parity-check (LDPC) codes in applications requiring error control coding is due to their capacity approaching performance which can be achieved with practically implementable iterative decoding algorithms. LDPC codes were first discovered by Gallager in 1962 and then rediscovered in late 1990’s. Ever since their rediscovery, a great deal of research effort has been expended in design, construction, structural analysis, efficient encoding and decoding, performance analysis, generalizations and applications of LDPC codes. Numerous papers have been published on these subjects. Many LDPC codes have been chosen as the standard codes for various next generations of communication systems and they are appearing in recent data storage products.
In this and the following lectures, recent developments of LDPC codes, their constructions, applications and possible research directions are presented.
讲座2：A Transform Approach for Construction and Analysis of Quasi-Cyclic LDPC Codes
Abstract：A matrix-theoretic approach for studying quasi-cyclic codes based on matrix transformations via Fourier transforms and row and column permutations is developed. These transformations put a parity-check matrix in the form of an array of circulant matrices into a diagonal array of matrices of the same size over an extension field. The approach is amicable to the analysis and construction of quasi cyclic low-density parity-check codes since it takes into account the specific parity-check matrix used for decoding with iterative message-passing algorithms. Based on this approach, the dimension of the codes and parity-check matrices for the dual codes can be determined. Several algebraic and geometric constructions of quasi-cyclic codes are presented as applications along with simulation results showing their performance over AWGN channels decoded with iterative message-passing algorithms.
讲座3：Trapping Sets of Structured LDPC Codes
Abstract：LDPC codes perform amazingly well with iterative decoding based on belief propagation using algorithms such as the sum-product algorithm or the min-sum algorithm. However, with iterative decoding, most LDPC codes have a common severe weakness, known as the error-floor. The error-floor of an LDPC code is characterized by the phenomenon that, as the SNR continues to increase, the error probability suddenly drops at a rate much slower than that in the region of low to moderate SNR. High error-floors may preclude LDPC codes from applications where very low error rates are required. High error-floors most commonly occur for unstructured random or pseudo-random LDPC codes constructed using computer-based methods or algorithms. Structured LDPC codes constructed algebraically, such as finite geometry and finite field LDPC codes, in general, have much lower error-floors.
Ever since the phenomenon of the error-floors of LDPC codes with iterative decoding became known, a great deal of research effort has been expended in finding its causes and methods to resolve or mitigate the error-floor problem. For the AWGN channel, the error-floor of an LDPC code is mostly caused by an undesirable structure, known as a trapping set, in the Tanner graph of the code based on which the decoding is carried out. In this presentation, we are concerned with the trapping set structure of the Tanner graphs of RC-constrained LDPC codes. For several classes of RC-constrained regular LDPC codes constructed algebraically, we show that their Tanner graphs contain no trapping sets of sizes smaller than their minimum weights. Consequently, their error-floor performances are dominated by their minimum weights.