應哈工大電信學(xué)院孟維曉教授、于啟月教授邀請，信息論與編碼，信息安全領(lǐng)域的國際著(zhù)名學(xué)者、臺北大學(xué)IEEE Fellow韓永祥教授將于2018年9月1日-2018年9月8日來(lái)哈爾濱工業(yè)大學(xué)訪(fǎng)問(wèn)講學(xué)和交流研討。并將分別于2018年9月2日、9月7日進(jìn)行學(xué)術(shù)講座，歡迎全校感興趣的師生參加。

講學(xué)時(shí)間：2018年9月2日上午 10:00-11:30

講學(xué)地點(diǎn)：哈工大科學(xué)園2A棟1011多媒體教室

講學(xué)題目1:  Efficient Decoding over Unknown Impulsive Noise Channels

報告內容簡(jiǎn)介：

It has been known from many researches that communication systems are susceptible to memoryless impulsive noise characterized by, for instance, the Bernoulli-Gaussian model. In order to combat this obstacle, channel coding has long served as an effective tool, especially in the context of moderately frequent occurrence of impulses, when the statistics of impulsive noise can be realized at the decoder. In this talk, irrespective of the statistics of impulses, an efficient decoding scheme is introduced by incorporating clipping-featured technique into the Viterbi algorithm. As a result, the proposed decoding scheme, while having a complexity at the same order as that of the Viterbi algorithm, is on a par with its optimal counterpart, for which statistics of impulses is assumed known at receiver, in terms of bit error probability. In addition, the Chernoff bounds of the bit error probabilities of the devised decoding algorithm are derived for both Bernoulli-Gaussian noise model and Middleton Class-A noise model. Comparisons between the bounds we derived and the simulated error rates under a variety of settings indicate that the ensuing analysis can provide critical insights for the efficacy of the proposed decoding approach when dealing with precarious frequent strong impulses.

講學(xué)時(shí)間：2018年9月7日上午 10:00-11:30

講學(xué)地點(diǎn)：哈工大科學(xué)園2A棟1011多媒體教室

講學(xué)題目1:  Novel FFT over Binary Finite Fields and Its Application to Reed-Solomon Erasure Codes

報告內容簡(jiǎn)介：

Abstract A fundamental issue in algebra is to reduce the computational complexities of arithmetic operations over polynomials. Many fast polynomialrelated algorithms, such as encoding/decoding of Reed-Solomon codes, are based on fast Fourier transforms (FFT). However, it is algorithmically harder as the traditional fast Fourier transform (FFT) cannot be applied directly over characteristic-2 finite fields. To the best of our knowledge, no existing algorithm for characteristic-2 finite field FFT/polynomial multiplication has provably achieved O(h log2(h)) operations. In this talk, we present a new basis of polynomial over finite fields of characteristic-2 and then apply it to the encoding/decoding of Reed-Solomon erasure codes. The proposed polynomial basis allows that h-point polynomial evaluation can be computed in O(h log2(h)) finite field operations with small leading constant. As compared with the canonical polynomial basis, the proposed basis improves the arithmetic complexity of addition, multiplication, and the determination of polynomial degree from O(h log2(h) log2 log2(h)) to O(h log2(h)). Based on this basis, we then develop the encoding and erasure decoding algorithms for the (n = 2r; k) Reed-Solomon codes. Thanks to the efficiency of transform based on the polynomial basis, the encoding can be completed in O(n log2(k)) finite field operations, and the erasure decoding in O(n log2(n)) finite field operations. To the best of our knowledge, this is the first approach supporting Reed-Solomon erasure codes over characteristic-2 finite fields while achieving a complexity of O(n log2(n)), in both additive and multiplicative complexities. As the complexity of leading factor is small, the algorithms are advantageous in practical applications. 

This work was presented at the 55th Annual Symposium on Foundations of Computer Science (FOCS 2014).

報告人簡(jiǎn)介：

   韓永祥教授1984年畢業(yè)于臺灣清華大學(xué)電機工程學(xué)系并于1986年于同系取得碩士學(xué)位。1993年韓教授于紐約州雪城大學(xué)獲得計算機與信息科學(xué)博士。他曾于華梵人文科技學(xué)院，暨南國際大學(xué)，以及臺北大學(xué)任教。從2010年8月到2017年1月，他任教于臺灣科技大學(xué)電機工程系并于2011年6月榮任學(xué)校講座教授。2015年2月起，他同時(shí)是臺北大學(xué)講座教授。目前擔任東莞理工學(xué)院電子工程與智能化學(xué)院杰出人才特聘教授。

   韓教授的研究興趣主要是在錯誤控制碼，無(wú)線(xiàn)網(wǎng)絡(luò )和資訊安全。韓教授已從事最先進(jìn)的錯誤控制碼解碼研究超過(guò)20年。20年前他首先開(kāi)發(fā)了基于A*算法的連續型解碼演算法。當時(shí)，該演算法吸引了大量的關(guān)注，因為它是對二進(jìn)制線(xiàn)性區塊碼最有效的最大似然軟性決定解碼演算法。此解碼演算法已被收錄于錯誤控制碼的經(jīng)典教科書(shū)中。

   韓教授還成功地應用編碼理論于無(wú)線(xiàn)傳感器網(wǎng)絡(luò )的研究領(lǐng)域。他已出版幾個(gè)關(guān)于無(wú)線(xiàn)傳感器網(wǎng)絡(luò )研究的高被引用著(zhù)作。其中一篇關(guān)于隨機密鑰預分配方案著(zhù)作被引用超過(guò)二千次。他還擔任多個(gè)國際學(xué)術(shù)刊物的編輯。韓教授是1994年雪城大學(xué)博士論文獎得主，同時(shí)也是IEEE院士。2013年他的一篇論文贏(yíng)得了久負盛名的ACM CCS Test of Time獎。此獎項為ACM資訊安全領(lǐng)域的年度最有影響力論文獎。