Search for: end-to-end
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    A fast and reliable multi-sender algorithm for peer-to-peer networks

    , Article Journal of Network and Computer Applications ; Volume 32, Issue 3 , May , 2009 , Pages 733–740 Firooz, M. H. (Mohammad Hamed) ; Sharif University of Technology
    Due to special constraints in peer-to-peer (P2P) networks (such as bandwidth limitation) and because of their highly dynamic characteristics, a single node cannot provide a reliable multimedia stream to the receivers. Several multi-sender algorithms are proposed to reliably deliver a media stream to the receiver through the intrinsically unreliable P2P networks. Based on upload bandwidths and availability of peers as well as the bandwidths of the links connecting the senders and the receiver, PROMISE selects a set of active senders to maximize the expected bit-rate delivered to the receiver. By careful investigation of PROMISE, in this paper, we present why and how it deviates from finding... 

    On tradeoff between collision and cooperation in a random access wireless network with energy harvesting nodes

    , Article IEEE Transactions on Vehicular Technology ; Volume 67, Issue 3 , 2018 , Pages 2501-2513 ; 00189545 (ISSN) Moradian, M ; Ashtiani, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    In this paper, we investigate an energy harvesting cooperative network in which the cooperation is done in a random access environment. Although the cooperation provides an extra harvested energy supply for transmissions of the source, it causes probable collisions for the transmitted source packets. Thus, this kind of cooperation can improve or degrade the QoS of the source packets. We find the optimal policy in such a scenario to maximize the source throughput and derive the necessary and sufficient condition for no-cooperation policy to be throughput-optimal. Then, we prove that the maximum throughput is obtained by considering no-cooperation or full-cooperation policy depending on the... 

    Improvement of AODV Routing Protocol in VANETs

    , M.Sc. Thesis Sharif University of Technology Kadkhoda Mohammad Mosaferi, Kaveh (Author) ; Hemmatyar, Ali Mohammad Afshin (Supervisor)
    Vehicular ad hoc networks (VANETs) can prepare scalable and cost effective solutions for applications such as traffic monitoring and vehicle safety. However, VANETs often experience congestion quicker than wired networks, leading to high end to end delay. The optimization method was proposed to improve the end to end delay of Ad-hoc On-demand Distance Vector (AODV) routing protocol in VANETs. It was shown that Last-In-First-Out with FrontDrop (LIFO-FD) queuing system for AODV routing protocol performs better in high traffic periods in term of end to end delay. The simulation studies were performed on the impact of queuing systems on end to end delay of AODV routing protocol in VANETs. The... 

    Improve Quality of Service in Multi-hop Cognitive Radio Networks

    , M.Sc. Thesis Sharif University of Technology Elahi, Mohammad (Author) ; Hemmatyar, Ali Mohammad Afshin (Supervisor)
    Introducing a new paradigm, cognitive radio, for spectrum utilization of unlicensed users, new research on spectrum utilization of licensed users was planned. The results show inefficiency of spectrum usage, so cognitive radio network was introduced. Cognitive radio network should not have any affect on primary users activity, so these networks face with some chalenges and the important ones is the supporting of the QoS.
    In this thesis after analyzing of the proposed routing metrics for finding best end-to-end path, the important ones of them were selected for more precise analyzing. After analyzing we find some disadvantage, can be improved by multi-radio. Although all of these metrics... 

    S-NC: Structure-free network coding-aware routing in wireless sensor networks

    , Article MSWiM'12 - Proceedings of the 15th ACM International Conference on Modeling, Analysis and Simulation of Wireless and Mobile Systems ; 2012 , Pages 403-407 ; 9781450316286 (ISBN) Enayati Noabadi, E ; Yousefi, H ; Movaghar, A ; Sharif University of Technology
    Network Coding (NC) is an emerging technique that helps wireless networks to have higher throughput and better energy efficiency. In this paper, a novel network coding-aware routing (S-NC) which uses NC to improve reliability and robustness in unreliable WSNs is proposed. It is based on a structure-free routing algorithm as the underlying routing engine which employs neighbor queue length to increase coding opportunity; while exploiting a spatial coding method to control the amount of redundancy. To the best of our knowledge, this is the first study on the topic of network codingaware routing in Wsns. Simulation results in Tossim demonstrate that S-NC significantly improves the performance... 

    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... 

    On reliable routing in wireless networks with diversity

    , Article 4th IEEE and IFIP International Conference on Wireless and Optical Communications Networks, WOCN 2007, Singapore, 2 July 2007 through 4 July 2007 ; 2007 ; 1424410045 (ISBN); 9781424410040 (ISBN) Shariatpanahi, P ; Foroughmand Aarabi, H ; Sharif University of Technology
    Many forms of diversity have been exploited in communication systems to combat fading nature of wireless channels. Some examples are time diversity, frequency diversity, space diversity and multiuser diversity. However, another form of diversity inherent in any wireless network, which is usually not exploited, is the diversity due to the shared medium of propagation. When in a network one node transmits to the other node, all the other nodes may hear this transmission and some of them can decode the data as well. This data can be used later to enhance the end-to-end network reliability. Previous works mostly consider some special cases of relay nodes configurations, not the general case. In... 

    Performability estimation of network services in the presence of component failures

    , Article 2006 Int. Conf. on Telecommunications and Networking, TeNe 2006, and the 2006 Int. Conf. on Industrial Electronics, Technology and Automation, IETA 2006, Part of the CISSE 2006, 4 December 2006 through 14 December 2006 ; 2007 , Pages 323-328 ; 9781402062650 (ISBN) Bidmeshki, M. M ; Shaad Zolpirani, M ; Miremadi, S. G ; Sharif University of Technology
    Springer Science and Business Media B.V  2007
    This paper presents a performability estimation approach which measures the ability of a network to deliver its services in the presence of component failures. The measurement is based on two important network service parameters, the endto- end delay and the packet loss. To evaluate the approach, different network topologies are studied using the OPNET Modeler. The results of simulations for four random topologies and two routing protocols, the RIP and the OSPF are presented and compared. The OSPF protocol with different delay timer values is also evaluated. © 2007 Springer  

    Low energy yet reliable data communication scheme for network-on-chip

    , Article IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems ; Volume 34, Issue 12 , 2015 , Pages 1892-1904 ; 02780070 (ISSN) Jafarzadeh, N ; Palesi, M ; Eskandari, S ; Hessabi, S ; Afzali-Kusha, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    In this paper, a low energy yet reliable communication scheme for network-on-chip is suggested. To reduce the communication energy consumption, we invoke low-swing signals for transmitting data, as well as data encoding techniques, for minimizing both self and coupling switching capacitance activity factors. To maintain the communication reliability of communication at low-voltage swing, an error control coding (ECC) technique is exploited. The decision about end-To-end or hop-To-hop ECC schemes and the proper number of detectable errors are determined through high-level mathematical analysis on the energy and reliability characteristics of the techniques. Based on the analysis, the extended... 

    Model predictive control versus traditional proportional delay differentiation algorithms

    , Article Canadian Journal of Electrical and Computer Engineering ; Volume 34, Issue 1 , 2009 , Pages 3-9 ; 08408688 (ISSN) Mahramian, M ; Taheri, H ; Haeri, M ; Sharif University of Technology
    An approximated quadratic programming optimization is proposed to determine a model predictive controller to guarantee end-to-end delay in the DiffServ architecture. The proposed algorithm, called the suboptimal model predictive control scheduler (SMPCS), regulates the service rates of aggregated traffic classes dynamically, such that some constraints on proportional or absolute delay can be guaranteed. This paper investigates SMPCS complexity and its implementation problems in high-speed routers. The main problem of model predictive control (and one which has limited its use to slow processes) is its complexity. Optimization is the most computationally complex part in a model predictive... 

    End-to-end speech recognition using lattice-free MMI

    , Article 19th Annual Conference of the International Speech Communication, INTERSPEECH 2018, 2 September 2018 through 6 September 2018 ; Volume 2018-September , 2018 , Pages 12-16 ; 2308457X (ISSN) Hadian, H ; Sameti, H ; Povey, D ; Khudanpur, S ; Sharif University of Technology
    International Speech Communication Association  2018
    We present our work on end-to-end training of acoustic models using the lattice-free maximum mutual information (LF-MMI) objective function in the context of hidden Markov models. By end-to-end training, we mean flat-start training of a single DNN in one stage without using any previously trained models, forced alignments, or building state-tying decision trees. We use full biphones to enable context-dependent modeling without trees, and show that our end-to-end LF-MMI approach can achieve comparable results to regular LF-MMI on well-known large vocabulary tasks. We also compare with other end-to-end methods such as CTC in character-based and lexicon-free settings and show 5 to 25 percent... 

    Improving Routing Protocols in VANETs

    , M.Sc. Thesis Sharif University of Technology Ahmadi, Arman (Author) ; Hemmatyar, Ali Mohammad Afshin (Supervisor)
    Vehicular ad-hoc networks are forms of mobile ad-hoc networks in which every vehicle can be smart and communicate with surrounding cars and roadside units. The main differences between these networks and mobile ad-hoc networks are high mobility and rapid changes in network connectivity as well as higher scalability and extensibility. The main goal in the vehicular ad-hoc networks is to increase safety for both the passengers and the driver. Since there are high mobility and rapid changes in network connectivity in such networks, there may be no path from a specific source to a destination, so design of new protocols to guarantee parameters such as reliability and less overhead would be... 

    Study of End-to-End Voting Systems Helios and Scantegrity II

    , M.Sc. Thesis Sharif University of Technology Chitgar, Ismael (Author) ; Khazaei, Shahram (Supervisor)
    Voting is a detachable part of the democratic governments. In the era of modern computer systems, the need for electronic voting systems in no longer avoidable.Designing a secure electronic voting system is a difficult problem since both privacy and integrity must be achieved at the same time. This difficulty has cast the problem to the center of attention of many researchers.In this thesis we will consider the new generation of voting systems known as end-to-end that were designed to solve the problems in the previous generations of voting systems and to uphold the security of the system. Many of end-toend voting systems use concepts of cryptography in addition to machine tools.A central... 

    Multiple Description Video Coding Based on Base and Enhancement Layers of SVC and Channel Adaptive Optimization

    , Ph.D. Dissertation Sharif University of Technology Kazemi Varnamkhasti, Mohammad (Author) ; Haj Sadghi, Khosrow (Supervisor) ; Shirmohammadi, Shervin (Supervisor)
    Multiple distortion coding is a promising solution for video transmission over lossy channels. In MDC multiple descriptions of a source are generated which are independently decodable and mutually refinable. When all descriptions are available, the corresponding quality is called central quality; otherwise it is called side quality. Generally, there exist a trade-off between side and central quality in all MDC schemes. The MDC methods which provide better central-side quality trade-off are of more interest to the designers.In this thesis a new MDC scheme is introduced which has better trade-off between side and central quality. In other words, for the same central quality, it provides higher... 

    Active Trust Routing in MANETs

    , M.Sc. Thesis Sharif University of Technology Alipanah, Javad (Author) ; Hemmatyar, Ali Mohammad Afshin (Supervisor)
    The use of MANETs in many areas is rapidly spreading. Due to dynamic nature,and limited energy of this networks, they are vulnerable to some attacks including blackhole attack. Blackhole attack can disrupt the commiunication between hosts and cause denial of service. One of countermeasures to this attack which has been recently proposed is the ActiveTrust. ActiveTrust is a routing protocol which relys on malicious node detection using trust calculations; this scheme has been proposed for WSNs. In this work we adopt the ActiveTrust’s idea and try to apply it into MANETs. Then we simulate the resulting proposal in NS-3 and compare the results  

    Generating Control Commands for an Autonomous Vehicle Based on Environmental Information

    , M.Sc. Thesis Sharif University of Technology Azizabadi Farahani, Fatemeh (Author) ; Bagheri Shouraki, Saeed (Supervisor)
    A self-driving car is a vehicle that can understand its environment and operate without human intervention. In the past decades, deep learning and artificial intelligence (AI) have significantly influenced the autonomous driving revolution in academia and industry. Also, neural networks have become increasingly crucial for generating control commands for autonomous vehicles. Generating control commands such as steering angle, brake, throttle, and appropriate speed is essential for self-driving cars. This thesis presents an End-to-End approach to generating these control commands. The convolutional neural network receives the raw frames of the road image with the help of a camera placed on... 

    Energy efficient and high speed error control scheme for real time wireless sensor networks

    , Article International Journal of Distributed Sensor Networks ; Vol. 2014 , 2014 Barati, A ; Movaghar, A ; Sabaei, M ; Sharif University of Technology
    Reliability and energy consumption are two of the main constraints in wireless sensor networks (WSNs). In this paper, a novel energy efficient and high speed error control scheme is introduced that is based on the Redundant Residue Number System (RRNS) allowing real-time application of WSNs. The proposed approach employs a new 3-moduli set {22n+1, 2 2n1-1, 2n- 1 } and an efficient reverse converter which relies on the Mixed Radix Conversion (MRC) algorithm and achieves significant improvements both in terms of conversion delay and hardware design. In order to obtain error controllability, two-redundant-moduli set 23n+1 - 1, 24n+1 - 1 is also added to the main 3-moduli set. The theoretical... 

    Locality aware P2P overlay architecture for live video streaming

    , Article 2012 6th International Symposium on Telecommunications, IST 2012 ; 2012 , Pages 650-655 ; 9781467320733 (ISBN) Bayat, N ; Akbari, B ; Rabiee, H. R ; Salehi, M ; Sharif University of Technology
    Recently, using Peer-to-Peer (P2P) overlay architectures have become a popular approach for live video streaming over the Internet. Since the peers in these systems are geographically distributed, the communication between them imposes huge redundant traffic into the Internet. One solution to address this problem is utilizing the locality aware algorithms to optimize the neighbor selection policy. However, for real-time applications like live video streaming we need to consider the trade-off between localizing the traffic and service quality. In this paper, we propose a novel pure P2P framework through two phases; (1) Local tracker selection, and (2) Overlay mesh construction. We introduce... 

    Distributed QoS routing algorithm in large scale wireless sensor networks

    , Article IEEE International Symposium on Industrial Electronics ; 2012 , Pages 826-830 ; 9781467301589 (ISBN) Kordafshari, M. S ; Pourkabirian, A ; Meybodi, M. R ; Movaghar, A ; Sharif University of Technology
    IEEE  2012
    This paper presents a novel routing protocol based on the Learning Automata method for large scale Wireless Sensor Networks (WSNs) codenamed DRLR (distributed reinforcement learning routing). In this method, each node is equipped with learning automata so that it can learn the best path to transmit data toward the sink. The approach proved to be efficient, reliable, and scalable. It also prevents routing hole by considering network density and average of energy levels available. The approach also increases network lifetime by balancing energy consumption. We compared our approach to two other methods (MMSPEED and EESPEED) and the simulation results show our algorithm to better meet... 

    Thermal conductivity of polyamide-6,6 in the vicinity of charged and uncharged graphene layers: A molecular dynamics analysis

    , Article Journal of Physical Chemistry C ; Volume 116, Issue 26 , May , 2012 , Pages 14115-14122 ; 19327447 (ISSN) Alaghemandi, M ; Gharib-Zahedi, M. R ; Spohr, E ; Böhm, M. C ; Sharif University of Technology
    The thermal conductivity (λ) of nanoconfined polyamide-6,6 (PA) oligomers in polymer-graphene nanocomposites has been investigated by reverse nonequilibrium molecular dynamics (RNEMD) simulations. The preferential alignment of the PA chains parallel to the graphene plane as well as their elongation implies that λ of the polymer in nanocomposites is larger than that in the neat polymer system. The ordering of the polymer phase is enhanced in an arrangement of charged graphene surfaces made of one layer with a charge deficit and one with a charge excess. The consequence of the enhanced polymer ordering as well as the denser packing is an increase in λ in the polymer network. Differences in the...