Search for: network-coding
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    Secure noisy network coding

    , Article 2013 Iran Workshop on Communication and Information Theory ; 2013 ; 9781467350235 (ISBN) Yassaee, M. H ; Aref, M. R ; Gohari, A ; Sharif University of Technology
    In this paper we use the Output Statistics of Random Binning (ORSB) framework to extend the noisy network coding of Lim et al. to include an eavesdropper  

    QoSNC: A novel approach to qos-based network coding for fixed networks

    , Article Journal of Communications and Networks ; Volume 12, Issue 1 , 2010 , Pages 86-94 ; 12292370 (ISSN) Salavati, A. H ; Khalaj, B. H ; Crespo, P. M ; Aref, M. R ; Sharif University of Technology
    In this paper, we present a decentralized algorithm to find minimum cost quality of service (QoS) flow subgraphs in network coded multicast schemes. The main objective is to find minimum cost subgraphs that also satisfy user-specified QoS constraints, specifically with respect to rate and delay demands. We consider networks with multiple multicast sessions. Although earlier network coding algorithms in this area have demonstrated performance improvements in terms of QoS parameters, the proposed QoS network coding approach provides a framework that guarantees QoS constraints are actually met over the network. Flow optimization, network coding, quality of service (QoS)  

    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 linear index coding from graph homomorphism perspective

    , Article 2015 Information Theory and Applications Workshop, ITA 2015 - Conference Proceedings, 1 February 2015 through 6 February 2015 ; 2015 , Pages 220-229 ; 9781479971954 (ISBN) Ebrahimi, J. B ; Jafari Siavoshani, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    In this work, we study the problem of linear index coding from graph homomorphism point of view. We show that the decision version of linear (scalar or vector) index coding problem is equivalent to certain graph homomorphism problem. Using this equivalence expression, we conclude the following results. First we introduce new lower bounds on linear index of graphs. Next, we show that if the linear index of a graph over a finite filed is bounded by a constant, then by changing the ground field, the linear index of the graph may change by at most a constant factor that is independent from the size of the graph. Finally, we show that the decision version of linear index coding problem is... 

    Convolutional network-coded cooperation in multi-source networks with a multi-antenna relay

    , Article IEEE Transactions on Wireless Communications ; Vol. 13, issue. 8 , 2014 , pp. 4323-4333 ; ISSN: 15361276 Karbalayghareh, A ; Nasiri-Kenari, M ; Hejazi, M ; Sharif University of Technology
    We propose a novel cooperative transmission scheme called Convolutional Network-Coded Cooperation (CNCC) for a network including N sources, one M-antenna relay, and one common destination. The source-relay (S-R) channels are assumed to be Nakagami-m fading, while the source-destination (S-D) and the relay-destination (R-D) channels are considered Rayleigh fading. The CNCC scheme exploits the generator matrix of a good (N + M', N,v) systematic convolutional code, with the free distance of dfree designed over GF(2), as the network coding matrix which is run by the network's nodes, such that the systematic symbols are directly transmitted from the sources, and the parity symbols are sent by the... 

    A push-pull network coding protocol for live peer-to-peer streaming

    , Article Computer Networks ; Volume 130 , 2018 , Pages 145-155 ; 13891286 (ISSN) Ayatollahi, H ; Khansari, M ; Rabiee, H. R ; Sharif University of Technology
    Elsevier B.V  2018
    In this paper, we propose a new peer-to-peer (P2P) video streaming protocol which presents an implementation of network coding with a new caching mechanism. It employs a push-pull mechanism for sending the video chunks between peers. More specifically, this push-pull mechanism gives priority to the video chunks according to their video layers. The video base layer is transmitted through a pushing mechanism while the enhancement layers employ a pulling mechanism. Moreover, in the network coding algorithm of this protocol, we introduce a caching mechanism to improve the network's performance as well as the video streaming quality. The comprehensive simulations show that the proposed protocol... 

    Improvement of Security Features of Communication Networks with Network Coding

    , M.Sc. Thesis Sharif University of Technology Mousavi, Nima (Author) ; Aref, Mohammad Reza (Supervisor) ; Salmasizadeh, Mahmoud (Supervisor)
    In this thesis, we study security features of the networks which use linear network coding to multicast information to some nodes of the network in presence of a wiretapper and also an active intruder. We consider information theoretic security in which we assume no computation limits for enemy. Thus, we take advantage of the essence of network coding instead of cryptographic tools to improve security features of the network. First, we show how providing shannon security for such networks in presence of wiretapper, leads to different cost in multicast rate, depending on initial network code designed. Based on this, we present a modified secure network code design which can provide perfect... 

    Maximum stable throughput of network-coded multiple broadcast sessions for wirelesstandem random access networks

    , Article IEEE Transactions on Mobile Computing ; Vol. 13, issue. 6 , 2014 , pp. 1256-1267 ; ISSN: 15361233 Amerimehr, M. H ; Ashtiani, F ; Valaee, S ; Sharif University of Technology
    This paper presents an analytical study of the stable throughput for multiple broadcast sessions in a multi-hop wireless tandem network with random access. Intermediate nodes leverage on the broadcast nature of wireless medium access to perform inter-session network coding among different flows. This problem is challenging due to the interaction among nodes, and has been addressed so far only in the saturated mode where all nodes always have packet to send, which results in infinite packet delay. In this paper, we provide a novel model based on multi-class queueing networks to investigate the problem in unsaturated mode. We devise a theoretical framework for computing maximum stable... 

    On the equivalency of reliability and security metrics for wireline networks

    , Article IEEE International Symposium on Information Theory - Proceedings, 25 June 2017 through 30 June 2017 ; 2017 , Pages 2713-2717 ; 21578095 (ISSN) ; 9781509040964 (ISBN) Mojahedian, M. M ; Gohari, A ; Aref, M. R ; Sharif University of Technology
    'To be considered for the 2017 IEEE Jack Keil Wolf ISIT Student Paper Award' In this paper, we show the equivalency of weak and strong secrecy conditions for a large class of secure network coding problems. When we restrict to linear operations, we show the equivalency of 'perfect secrecy with zero-error constraint' and 'weak secrecy with-error constraint'. © 2017 IEEE  

    Blind index coding

    , Article IEEE Transactions on Information Theory ; Volume 63, Issue 4 , 2017 , Pages 2076-2097 ; 00189448 (ISSN) Kao, D.T.H ; Maddah Ali, M. A ; Avestimehr, A. S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    We introduce the blind index coding (BIC) problem, in which a single sender communicates distinct messages to multiple users over a shared channel. Each user has partial knowledge of each message as side information. However, unlike classical index coding, in BIC, the sender is uncertain of what side information is available to each user. In particular, the sender only knows the amount of bits in each user's side information but not its content. This problem can arise naturally in caching and wireless networks. In order to blindly exploit side information in the BIC problem, we develop a hybrid coding scheme that XORs uncoded bits of a subset of messages with random combinations of bits from... 

    Applying Network Coding in a Mesh-Based Peer-to-Peer Streaming Network

    , M.Sc. Thesis Sharif University of Technology Ayatollahi Tabatabaei, Hoda (Author) ; Khansari, Mohammad (Supervisor) ; Rabiei, Hamid Reza (Supervisor)
    The emerging peer-to-peer (P2P) networks become more popular among researchers in different applications such as file sharing, and video streaming. Since various P2P networks provide high performance and scalable interaction among peers, they are very efficient in designing distributed multimedia applications such as live streaming, IPTV, VoIP, and multimedia broadcasting. In order to improve the network throughput and downloading performance of P2P networks for multimedia streaming, network coding is a technique which can be used for these purposes. In this thesis, we propose a peer-to-peer (P2P) video streaming protocol which presents an implementation of network coding technique. The... 

    LiveCod: A mesh-pull P2P live streaming system with XOR-based network coding

    , Article 2010 IEEE Globecom Workshops, GC'10 ; 2010 , Pages 436-441 ; 9781424488650 (ISBN) Ayatollahi Tabatabaii, S. H ; Khansari, M ; Rabiee, H. R ; Sharif University of Technology
    This paper presents a mesh-pull peer-to-peer (P2P) live video streaming system. The proposed XOR-based Network Coding (XOR-NC) system is based on GIA protocol and introduces new search and answer data formats for chunks which are used by the network coding algorithm for exchanging data among peers. The search message contains the XORed GOP (Group of Picture) keys and some meta-data such as search key. The answer message, however, has the XORed GOP data and a summary of video blocks of the encoded GOP. In order to reduce the encoding complexity at each peer, a new content-based cache (CCache) is also introduced. Comparison of LiveCod with traditional GIA and GIA with random network coding... 

    Impact of channel estimation errors and power allocation on analog network coding and routing in two-way relaying [electronic resource]

    , Article IEEE Transaction on Vehicular Technology ; Vol. 61, Issue 7, pp. 3223 - 3239, 2012 Tabataba, F. S. (Forough S.) ; Sadeghi, P ; Hucher, Ch ; Pakravan, Mohammad R ; Sharif University of Technology
    In this paper, we study two important transmission strategies in full-duplex two-way relaying in the presence of channel estimation errors. In analog network coding (ANC), the relay transmits the combined signals that were received from both sources, with the aim of achieving better spectral efficiency. However, due to imperfect channel-state information (CSI), sources cannot perfectly cancel their own data in the relayed signal. We derive an achievable information rate for ANC in imperfect-CSI conditions and show how the ANC performance can significantly be degraded as a result. Moreover, we derive cut-set bounds with channel estimation errors for traditional routing (TR), in which time... 

    A bandwidth-efficient scheme for distributed storage systems

    , Article 2008 2nd International Symposium on Advanced Networks and Telecommunication Systems, ANTS 2008, Mumbai, 15 December 2008 through 17 December 2008 ; May , 2008 ; 1424436001 (ISBN); 9781424436002 (ISBN) Bathaee, N. S ; Pakravan, M. R ; Sharif University of Technology
    In this paper, utilizing the benefits of network coding, we introduce a scheme for uncoordinated dynamic distributed storage systems in which nodes can randomly join and leave the storage network. The proposed scheme can reduce the bandwidth requirement of the storage network  

    Static network codes using network minimal subgraphs

    , Article 2nd International Conference on Electrical Engineering, ICEE, Lahore, 25 March 2008 through 26 March 2008 ; 2008 ; 9781424422937 (ISBN) Rezagholipour, M ; Ahmadian, M ; Aref, M. R ; Sharif University of Technology
    For a given multicast network problem, there are different solutions. Sometimes some links of a network may be removed by failure and then we will be encountered with link failure in the network. Therefore, one of the objectives of selecting a specific network code solution among different options is to increase the robustness provided by this solution against such failure. In this paper we extend the definition of the minimal subtree graph and replace it with a new definition of minimal subgraph and use it as a basis of a faster method with lower complexity for finding a static network code resistant against all solvable link failure patterns of a network. ©2008 IEEE  

    , M.Sc. Thesis Sharif University of Technology karbalai Ghareh, Alireza (Author) ; Nasiri Kenari, Masoumeh (Supervisor)
    In the recent years, the cooperative communications based on Network Coding have received significant attentions to simultaneously improve the diversity order and the network throughput. In this thesis, a new cooperative transmission scheme for the cooperative relay-based networks called “Convolutional Network-Coded Cooperation” (CNCC) is proposed, in which a systematic convolutional code is used in the network level. In this scheme, the systematic packets are directly transmitted by the sources, and the parity packets, calculated based on the received sources’ packets, are transmitted by the relays. The proposed CNCC scheme is considered in the cooperative networks including N sources, M... 

    Delay and throughput analysis of a two-way opportunistic network coding-based relay network

    , Article IEEE Transactions on Wireless Communications ; Vol. 13, issue. 5 , 2014 , p. 2863-2873 Amerimehr, M. H ; Ashtiani, F ; Sharif University of Technology
    This paper presents an analytical study of average delay and throughput in a two-way relay network exploiting network coding to exchange source packets, where arrival and departure of packets are stochastic. In this case, a fundamental problem for the relay node is whether to wait in order to obtain a coding opportunity, leading to reduction of the number of transmissions, or sending a packet (coded/uncoded) whenever it has a transmission opportunity, leading to reduction of the packet delay. In order to address the fundamental trade-off between packet delay and transmission power, we develop three network coding schemes based on power-delay constraint of the application. We devise a... 

    Cross-layer rateless coding over wireless relay networks

    , Article IWCMC 2011 - 7th International Wireless Communications and Mobile Computing Conference, 4 July 2011 through 8 July 2011 ; July , 2011 , Pages 1545-1549 ; 9781424495399 (ISBN) Shirvani Moghaddam, M ; Khalaj, B. H ; Pasandshanjani, E ; Sharif University of Technology
    The focus of the paper is on cross-layer transmission based on rateless coding for relay networks. In the proposed method, rateless coding is used at the packet level and a separate physical layer coding is used at the physical layer. As rateless codes are originally designed and optimized for erasure channels, using these codes at the physical layer can lead to significant performance degradation. The proposed scheme has the advantage of a cross-layer design which uses a rateless code at the packet level modeled by an erasure channel. Based on the analysis and simulation results provided in this paper, the cross-layer scheme results in earlier successful decoding at the destination  

    Physical layer network coding in molecular two-way relay networks

    , Article IWCIT 2016 - Iran Workshop on Communication and Information Theory, 3 May 2016 through 4 May 2016 ; 2016 ; 9781509019229 (ISBN) Farahnak Ghazani, M ; Aminian, G ; Mirmohseni, M ; Gohari, A ; Nasiri Kenari, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    In traditional wireless networks, physical layer network coding (PNC) exploits the inverse additivity property of broadcast signals in the medium, an idea which is not directly applicable to molecular networks. In this paper, to make the natural XOR operation possible at the physical layer, we exploit the reaction of different molecule types and we propose a PNC scheme in diffusion-based molecular relay networks. For comparison, we consider the straightforward network coding (SNC) scheme in molecular networks. Assuming the ligand-receptor binding process at the receivers, we investigate the error performance of both schemes. It is observed that in addition to the simplicity of the proposed... 

    Network Coding-based Packet Relaying in Wireless Networks

    , M.Sc. Thesis Sharif University of Technology Farhadi, Farzaneh (Author) ; Ashtiani, Farid (Supervisor)
    In this thesis, we propose two new network coding-based packet relaying schemes suitable for multiple unicast scenarios in a random access network. In such networks the channels may have memory dependent upon the random access scheme. Thus, the optimal scheme for memoryless channels reported recently in the literature is not necessarily optimal in random access networks. In our proposed schemes, we convert a multiple unicast scenario to a combination of multiple anycast and a few multicast scenarios. By such an approach, we exploit the channels between relay node and the other nodes, instead of using only one channel at each packet transmission, for as many as possible. By simple analytical...