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    An evolutionary approach to generalized mirror sites problem

    , Article 1st International Conference on Bio-Inspired Computational Methods Used for Solving Difficult Problems-Development of Intelligent and Complex Systems, BICS 2008, Tirgu Mures, 5 November 2008 through 7 November 2008 ; Volume 1117 , 2009 , Pages 40-46 ; 0094243X (ISSN); 9780735406544 (ISBN) Etemadi Tajbakhsh, S ; Movaghar, A ; Beigy, H ; Petru Maior University; Romanian Academy ; Sharif University of Technology
    The minimum cost subgraph for joint distributed source and network coding has been studied using a linear programming approach. This problem considers some statistically correlated information sources in a network, where sending over each link has a defined cost. The desired solution to this problem is a set of coding rates over the graph links, that minimizes the total communication costs. But in this problem, the placement of the sources is pre-defined, which is not necessarily optimal. In this paper, for the first time, we find a "good" placement for the sources using a genetic programming approach. This problem can be seen as the generalized mirror sites problem, where sources are not... 

    On the duality of additivity and tensorization

    , Article IEEE International Symposium on Information Theory - Proceedings, 14 June 2015 through 19 June 2015 ; Volume 2015-June , 2015 , Pages 2381-2385 ; 21578095 (ISSN) ; 9781467377041 (ISBN) Beigi, S ; Gohari, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    A function is said to be additive if, similar to mutual information, expands by a factor of n, when evaluated on n i.i.d. repetitions of a source or channel. On the other hand, a function is said to satisfy the tensorization property if it remains unchanged when evaluated on i.i.d. repetitions. Additive rate regions are of fundamental importance in network information theory, serving as capacity regions or upper bounds thereof. Tensorizing measures of correlation have also found applications in distributed source and channel coding problems as well as the distribution simulation problem. Prior to our work only two measures of correlation, namely the hypercontractivity ribbon and maximal... 

    On Körner-Marton's sum modulo two problem

    , Article IWCIT 2015 - Iran Workshop on Communication and Information Theory, 6 May 2015 through 7 May 2015 ; May , 2015 ; 9781479982356 (ISBN) Sefidgaran, M ; Gohari, A ; Aref, M. R ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    In this paper we study the sum modulo two problem proposed by Körner and Marton. In this source coding problem, two transmitters who observe binary sources X and Y, send messages of limited rate to a receiver whose goal is to compute the sum modulo of X and Y. This problem has been solved for the two special cases of independent and symmetric sources. In both of these cases, the rate pair (H(X|Y), H(Y|X)) is achievable. The best known outer bound for this problem is a conventional cut-set bound, and the best known inner bound is derived by Ahlswede and Han using a combination of Slepian-Wolf and Körner-Marton's coding schemes. In this paper, we propose a new outer bound which is strictly... 

    Generalised secure distributed source coding with side information

    , Article IET Communications ; Volume 4, Issue 18 , 2010 , Pages 2262-2272 ; 17518628 (ISSN) Salimi, S ; Salmasizadeh, M ; Aref, M. R ; Sharif University of Technology
    New inner and outer bounds on the achievable compression-equivocation rate region for generalised secure data compression with side information are given that do not match in general. In this setup, two senders, Alice and Charlie intend to transmit information to Bob via channels with limited capacity so that he can reliably reconstruct their observations. The eavesdropper, Eve, has access to one of the channels at each instant and is interested in the source of the same channel at the time. Bob and Eve also have their own observations, which are correlated with Alice's and Charlie's observations. In this model, two equivocation and compression rates are defined with respect to the sources... 

    Multimedia multicast based on multiterminal source coding

    , Article IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences ; Volume E93-A, Issue 9 , 2010 , Pages 1639-1649 ; 09168508 (ISSN) Aghagolzadeh, A ; Nooshyar, M ; Rabiee, H. R ; Mikaili, E ; Sharif University of Technology
    Multimedia multicast with two servers based on the mul- titerminal source coding is studied in some previous researches. Due to the possibility of providing an approach for practical code design for more than two correlated sources in IMTSC/CEO setup, in this paper, the framework of Slepian-Wolf coded quantization is extended and a practical code design is presented for IMTSC/CEO with the number of encoders greater than two. Then the multicast system based on the IMTSC/CEO is applied to the cases with three, four and five servers. Since the underlying code design approach for the IMTSC/CEO problem has the capability of applying to an arbitrary number of active encoders, the proposed MMBMSC... 

    Analysis of Universal Coding Algorithms for Some Special Classes of Information Sources

    , M.Sc. Thesis Sharif University of Technology Nangir, Mahdi (Author) ; Aref, Mohammad Reza (Supervisor) ; Behroozi, Hamid (Supervisor)
    The coding and compression of information sources with special probability distribution is the center of concentration of researchers in this field in the last decades. In this dissertation, after a concise introduction to source coding, we focus on the universal source coding and data compression from an algorithmic and information theoretic point of view. First we introduce the fundamental concepts of source coding and data compression. Then, we analysis some algorithms on integer coding and verify their universality and asymptotically optimality. Usually statistics of information sources is not available in communication systems and storage devices, so that applying universal source... 

    On the optimal performance in asymmetric gaussian wireless sensor networks with fading

    , Article IEEE Transactions on Signal Processing ; Volume 58, Issue 4 , 2010 , Pages 2436-2441 ; 1053587X (ISSN) Behroozi, H ; Alajaji, F ; Linder, T ; Sharif University of Technology
    We study the estimation of a Gaussian source by a Gaussian wireless sensor network (WSN) where L distributed sensors transmit noisy observations of the source through a fading Gaussian multiple access channel to a fusion center. In a recent work Gastpar, [ "Uncoded transmission is exactly optimal for a Simple Gaussian Sensor Network", IEEE Trans. Inf. Theory, vol. 54, no. 11, pp. 52475251, Nov. 2008] showed that for a symmetric Gaussian WSN with no fading, uncoded (analog) transmission achieves the optimal performance theoretically attainable (OPTA). In this correspondence, we consider an asymmetric fading WSN in which the sensors have differing noise and transmission powers. We first... 

    Crowdsummarizer: automated generation of code summaries for java programs through crowdsourcing

    , Article IEEE Software ; Volume 34, Issue 2 , 2017 , Pages 71-80 ; 07407459 (ISSN) Badihi, S ; Heydarnoori, A ; Sharif University of Technology
    To perform software maintenance, developers must have a relatively good understanding of the program's source code, which is often written by other developers. Code summaries, which describe a program's entities (for example, its methods), help developers better comprehend code more quickly. However, generating code summaries can be challenging. To mitigate this problem, CrowdSummarizer exploits crowdsourcing, gamification, and natural-language processing to automatically generate high-level summaries of Java program methods. Researchers have implemented it as an Eclipse plug-in together with a Web-based code summarization game that can be played by the crowd. Two empirical studies... 

    Software watermarking by equation reordering

    , Article 2008 3rd International Conference on Information and Communication Technologies: From Theory to Applications, ICTTA, Damascus, 7 April 2008 through 11 April 2008 ; 2008 ; 1424417511 (ISBN); 9781424417513 (ISBN) Shirali Shahreza, M ; Shirali Shahreza, S ; Sharif University of Technology
    Watermarking is the process of hiding information in a media and usually used to for copyright protection. In software watermarking, the information is added to the source code of program and can be extracted from compiled executable code. In this paper, a new software watermarking algorithm is proposed by equation reordering. In this method, the order of operands in an equation is changed according to the information we want to hide in a way that the result of the equation is unchanged. One of the main advantages of this method is that no code added to the program, so the size and speed of the program not changed  

    A secure error-resilient lossless source coding scheme based on punctured turbo codes

    , Article Iranian Journal of Electrical and Computer Engineering ; Volume 5, Issue 1 , 2006 , Pages 19-23 ; 16820053 (ISSN) Payandeh, A ; Ahmadian, M ; Aref, M. R ; Sharif University of Technology
    In this paper, we develop a new error-resistant secure lossless source coding scheme for discrete sources. Recent results indicate that the same turbo principle that provides sub-optimal strategy for channel coding, can be used to obtain efficient source coding schemes. We extend the source turbo-coding idea to include security for transmission of the compressed data and also to ensure the lossless recovery of information at the receiver. Compression and security are achieved by adapting the random puncturing strategy to the statistics of the source. Lossless compression is guaranteed by finely puncturing the encoded data of a parallel-concatenated turbo code while verifying the integrity of... 

    Source Coding with Polar Codes

    , M.Sc. Thesis Sharif University of Technology Eghbalian Arani, Sajjad (Author) ; Behroozi, Hamid (Supervisor)
    Polar codes were introduced by Arikan in 2009. These codes are the first family of codes that with low encoding complexity and successive cancellation decoder, can achieve the channel capacity. Polar codes, at first were implemented for channel coding, but in 2010 performance of these codes in binary and q-ary alphabet source was studied. It is shown that these codes can perform efficiently in channel coding and source coding. On the other hand, one of the most important continuous sources are Gaussian sources. Due to the importance of Gaussian sources and good performance of polar codes, we try to evaluate the performance of these codes in Gaussian sources. Note that, these codes have... 

    Code design for IMTSC/CEO problem using multilevel Slepian-Wolf coded quantization framework

    , Article Proceedings - 2010 18th Iranian Conference on Electrical Engineering, ICEE 2010, 11 May 2010 through 13 May 2010 ; 2010 , Pages 282-287 ; 9781424467600 (ISBN) Nooshyar, M ; Aghagolzadeh, A ; Rabiee, H. R ; Sharif University of Technology
    The aim of this paper is introducing coding scheme that can potentially achieve the sum rate-distortion bound of Gaussian IMTSC/CEO problem with arbitrary number of encoders. No previous work has been reported on code design for the IMTSC/CEO problem with the number of encoders greater than two. In this paper the framework of Slepian-Wolf coded quantization is extended to the case with the number of encoders greater than two. On the other hand, we apply the approach to the case of unequal levels of the observation noise at the encoders. Encoding process consists of trellis coded quantization (TCQ) and LDPC codes. The proposed framework can be easily used for any number of active encoders... 

    Joint Disrtibuted Source and Network Coding

    , M.Sc. Thesis Sharif University of Technology Etemadi Tajbakhsh, Shahriar (Author) ; Movaghar Rahimabadi, Ali (Supervisor)
    Network coding, as a novel technique, suggests that the intermediate nodes of a network can combine independent flows to optimize the usage of a shared communication channel. Also, distributed source coding, exploits the joint statistics of correlated information sources to reduce the volume of transmitted information. Surprisingly, it has been shown that linear network codes are able to compress correlated sources. In this project, we have focused on this problem, i.e. joint distributed source and network coding. We have two important contributions with different directions. First we give a practical design for joint coding. Second, we use an evolutionary approach to find the best placement... 

    Exploiting Applications and Improving Performance of Polar Codes in Information Theory

    , M.Sc. Thesis Sharif University of Technology Khatami, Mehrdad (Author) ; Marvasti, Farrokh (Supervisor)
    The two central topics of information theory are the compression and the transmission of data. Shannon, in his seminal work, formalized both these problems and determined their fundamental limits. Since then the main goal of coding theory has been to find practical schemes that approach these limits.Polar codes, recently invented by Arıkan, are the first practical codes that are known to achieve the capacity for a large class of channels. Their code construction is based on a phenomenon called “channel polarization”.
    Since the performance of polar code degrades when the block length is small, several kinds of Reed – Solomon concatenation is considered in order to improve the... 

    An Investigation on Entanglement and Its Applications in Quantum Communication Protocols

    , M.Sc. Thesis Sharif University of Technology Noshad, Morteza (Author) ; Aref, Mohammad Reza (Supervisor) ; Aminzadeh Gohari, Amin (Co-Advisor)
    In this thesis, we propose a new method for deriving the achievability results in quantum information theoretic problems. The calssical quan- tum decoupling lemma is an essential component in our method. Assume that each classical source is randomly binned at a finite rate. We find sufficient conditions on these rates such that the bin indices are nearly mutually independent of each other and of a quantum source Qn. Us- ing this theorem in conjunction with the calssical quantum Slepian Wolf (CQSW) result, this method suggest a new comprehensive framework for the achievability of network quantum information theoretic prob- lems. We’ve used the new method to redrive the Holevo bound, private... 

    Capacity and Security of Cooperative Information Systems with Correlated Sources

    , Ph.D. Dissertation Sharif University of Technology Salehkalaibar, Sadaf (Author) ; Aref, Mohammad Reza (Supervisor)
    The main problem in network information theory is how to send some sources in a network with multiple transmitters and receivers, in the presence of the noise and the interference.This problem is not solved in its general form and it needs source coding and channel coding. With the increase of users in a network, the secrecy becomes a challenging issue. The information-theoretic security is independent of the computational complexity.In this thesis, we investigate the transmission of correlated sources over information theoretic networks and study secrecy constraints in these networks. First, we study the secrecy of a one-receiver, two-eavesdropper broadcast channel with three degraded... 

    On the reliable transmission of correlated sources over two-relay network

    , Article 2013 IEEE Information Theory Workshop, ITW 2013 ; 2013 ; 9781479913237 (ISBN) Nasiraee, M ; Akhbari, B ; Ahmadian-Attari, M ; Aref, M. R ; Sharif University of Technology
    In this paper, we investigate reliable transmission of three correlated discrete memoryless sources over a two-relay network. In our considered model, one of the sources is available at the sender whereas, the other two sources are known to the first and the second relay. We present both joint and separate source-channel coding schemes, and derive the corresponding sets of sufficient conditions for reliable sources transmission. The manner of cooperation in both schemes is Decode-and-Forward strategy. In the joint approach, we generalize the correlation preserving mapping technique to our model using nested backward decoding. Our proposed separate approach is based on Slepian-Wolf source... 

    On the performance of polar codes for lossy compression of Gaussian sources

    , Article 2013 Iran Workshop on Communication and Information Theory, IWCIT 2013 ; 2013 ; 9781467350235 (ISBN) Eghbalian Arani, S ; Behroozi, H ; Sharif University of Technology
    In this work, we study the lossy source coding of a Gaussian source with polar codes. We show through two distributions on discrete alphabet, quantized approach as well as Central Limit Theorem (CLT) approach, when the alphabet size grows to infinity, polar codes can achieve the rate distortion bound for a Gaussian source. By comparing the rate of convergence on two distributions, we show that the quantized approach have a better convergence rate than the CLT approach  

    Deep relative attributes

    , Article 13th Asian Conference on Computer Vision, ACCV 2016, 20 November 2016 through 24 November 2016 ; Volume 10115 LNCS , 2017 , Pages 118-133 ; 03029743 (ISSN); 9783319541921 (ISBN) Souri, Y ; Noury, E ; Adeli, E ; Sharif University of Technology
    Springer Verlag  2017
    Visual attributes are great means of describing images or scenes, in a way both humans and computers understand. In order to establish a correspondence between images and to be able to compare the strength of each property between images, relative attributes were introduced. However, since their introduction, hand-crafted and engineered features were used to learn increasingly complex models for the problem of relative attributes. This limits the applicability of those methods for more realistic cases. We introduce a deep neural network architecture for the task of relative attribute prediction. A convolutional neural network (ConvNet) is adopted to learn the features by including an... 

    Restoration of damaged slices in images using matrix pseudo inversion

    , Article 22nd International Symposium on Computer and Information Sciences, ISCIS 2007, Ankara, 7 November 2007 through 9 November 2007 ; 2007 , Pages 98-103 ; 1424413648 (ISBN); 9781424413645 (ISBN) Ajorloo, H ; Manzuri Shalmani, M. T ; Lakdashti, A ; Sharif University of Technology
    A matrix pseudo inversion based method is developed for coding of images in real field in a way that at the receiver, one can restore the lost portions of the images. The proposed solution is similar to channel coding techniques, but it is done before source coding at the transmitter and after decoding of the compressed data at the receiver. Experiments show the effectiveness of the proposed solution in recove ring missed portions of the images and video frames. ©2007 IEEE