Search for: network-layers
0.006 seconds
Total 56 records

    Long Lifetime Multipath Routing in Unreliable Wireless Multimedia Sensor Networks

    , M.Sc. Thesis Sharif University of Technology Nikseresht, Ilnaz (Author) ; Movaghar Rahimabadi, Ali (Supervisor) ; Mehri, Bahman (Co-Advisor)
    Most of the current routing protocols in the WMSNs only consider the inter-path interference and not necessarily intra-path interference factor which is considered as one of the main causes of energy consumption in these networks. Among those protocols that consider this factor, none of them has ever come up with an algorithm capable of performing the routing without the need to use either the special hardware in the nodes (referred to as the GPS or directional antennas) or with the unrealistic assumption that the interference range is equal to the transmission range. The previously mentioned factors are critical in the sense that the former assumption results in more expensive sensor nodes... 

    Improving Quality of Service in Multimedia Wireless Sensor Networks

    , M.Sc. Thesis Sharif University of Technology Malool, Iman (Author) ; Hemmatyar, Ali Mohammad Afshin (Supervisor)
    Due to their specific characteristics such as huge data loads, heavy processes, various quality of service requirements (delay, jitter and reliability), multimedia streams have different necessities in comparison with normal data streams. The challenges of wireless sensor networks (process power, storage capacity and power limitations) add up to the challenges faced in WMSNs. In order to improve the quality of service in wireless multimedia sensor networks, attention must be paid to all the network layers. In this study improvement of quality of service is sought through the design of a protocol for the network layer of the wireless multimedia sensor network.
    This protocol tries to... 

    Physical layer encryption scheme using finite-length polar codes

    , Article IET Communications ; Volume 9, Issue 15 , 2015 , Pages 1857-1866 ; 17518628 (ISSN) Hooshmand, R ; Aref, M. R ; Eghlidos, T ; Sharif University of Technology
    Institution of Engineering and Technology  2015
    In this study, by exploiting the properties of finite-length polar codes, the authors introduce a physical layer encryption scheme to make secure (from a computational security perspective) and efficient communication between a sender (Alice) and a legitimate receiver (Bob) against both active and passive attacks, simultaneously. To prevent active attacks, two techniques are considered: (i) a novel method is introduced to keep the generator matrix of polar code secret from an active attacker (Oscar); (ii) a proper joint polar encoding/encryption algorithm based on the hidden generator matrix is introduced. Two additional strategies are considered against passive attacks: (i) a new method is... 

    3D hand pose estimation using RGBD images and hybrid deep learning networks

    , Article Visual Computer ; 2021 ; 01782789 (ISSN) Mofarreh Bonab, M ; Seyedarabi, H ; Mozaffari Tazehkand, B ; Kasaei, S ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    Hand pose estimation is one of the most attractive research areas for image processing. Among the human body parts, hands are particularly important for human–machine interactions. The advent of commercial depth cameras along with the rapid growth of deep learning has made great progress in all image processing fields, especially in hand pose estimation. In this study, using depth data, we introduce two hybrid deep neural networks to estimate 3D hand poses with fewer computations and higher accuracy compared with their counterparts. Due to the fact that the dimensions of data are reduced while passing through successive layers of networks, which causes data to be lost, we use the concept of... 

    Network layer challenges of IEEE 802.11n wireless ad hoc networks

    , Article Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering ; Volume 72 LNICST , 2012 , Pages 377-388 ; 18678211 (ISSN) ; 9783642291562 (ISBN) EffatParvar, M ; Yazdani, N ; EffatParvar, M ; Teymoori, P ; Movaghar, A ; Sharif University of Technology
    Recent demands toward high-speed wireless networks are growing. IEEE 802.11n, as the latest standard toward achieving higher speeds, aims to enhance IEEE 802.11 for higher throughputs. There are few works which analyze performance of this protocol in single-hop networks in terms of MAC layer-based parameters. Most of these works suggest disabling the RTS/CTS handshake to reduce MAC layer overheads. However, the effects of this protocol on the upper layers, especially the network layer, are still unknown. This paper deals with investigating performance of the network layer over IEEE 802.11n. Through extensive simulations performed in NS-2 we show that although network throughput is improved... 

    The simulation of microbial enhanced oil recovery by using a two-layer perceptron neural network

    , Article Petroleum Science and Technology ; Vol. 32, Issue. 22 , 2014 , pp. 2700-2707 ; ISSN: 10916466 Morshedi, S ; Torkaman, M ; Sedaghat, M. H ; Ghazanfari M.H ; Sharif University of Technology
    The authors simulated a reservoir by using two-layer perceptron. Indeed a model was developed to simulate the increase in oil recovery caused by bacteria injection into an oil reservoir. This model was affected by reservoir temperature and amount of water injected into the reservoir for enhancing oil recovery. Comparing experimental and simulation results and also the erratic trend of data show that the neural networks have modeled this system properly. Considering the effects of nonlinear factors and their erratic and unknown impacts on recovered oil, the perceptron neural network can develop a proper model for oil recovery factor in various conditions. The neural networks have not been... 

    Physical layer security for some classes of three-receiver broadcast channels

    , Article IET Communications ; Vol. 8, issue. 11 , July , 2014 , p. 1965-1976 Salehkalaibar, S ; Aref, M. R ; Sharif University of Technology
    In this study, the authors consider the secrecy of a one-receiver, two-eavesdropper broadcast channel (BC) with three degraded message sets. Consider a three-receiver BC with three messages, where the first message is decoded by all the receivers. The second message is decoded by the first and the second receivers and is to be kept secret from the third receiver. The third message is decoded by the first receiver and is to be kept secret from the second and the third receivers. The authors consider the imperfect secrecy condition at the second receiver, that is, it is allowed to partially decode the third message. However, the perfect secrecy condition at the third receiver, does not allow... 

    Proposing a hybrid protocol for secure wireless networks based on signcryption scheme

    , Article 2013 World Congress on Computer and Information Technology, WCCIT 2013 ; June , 2013 , Page(s): 1 - 6 ; 9781479904600 (ISBN) Darmian, N. R ; Oskoei, H. R. D ; Vazirnezhad, B ; Sharif University of Technology
    Considering the weaknesses of cryptography algorithms and the attacks performed against them, cryptography alone cannot guarantee the security of communication in a wireless network. With regard to the developments in wireless communication networks brought about by smart array antennas, security can be sought in the physical layer as well, aiming to restrict the access of the data in a wireless network and limit it to authorized users only in order to further restrain malicious data accesses. In this paper, we analysis a strategy for restricting data access using smart array antennas and present the results in security by a parameter called exposure region. For this strategy afterwards we... 

    Diffusion of innovations over multiplex social networks

    , Article Proceedings of the International Symposium on Artificial Intelligence and Signal Processing, AISP 2015, 3 March 2015 through 5 March 2015 ; 2015 , Pages 300-304 ; 9781479988174 (ISBN) Ramezanian, R ; Magnani, M ; Salehi, M ; Montesi, D ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    The ways in which an innovation (e.g., new behaviour, idea, technology, product) diffuses among people can determine its success or failure. In this paper, we address the problem of diffusion of innovations over multiplex social networks where the neighbours of a person belong to one or multiple networks (or layers) such as friends, families, or colleagues. To this end, we generalise one of the basic game-theoretic diffusion models, called networked coordination game, for multiplex networks. We present analytical results for this extended model and validate them through a simulation study, finding among other properties a lower bound for the success of an innovation. While simple and leading... 

    Spectrally encoded code division multiple access-based cognitive relay networks

    , Article IET Communications ; Volume 9, Issue 12 , August , 2015 , Pages 1510-1521 ; 17518628 (ISSN) Najafi, S ; Shayesteh, M. G ; Sharif University of Technology
    Institution of Engineering and Technology  2015
    Cognitive radio and cooperative networks are increasingly regarded as revolutionary technologies that utilise the radio spectrum efficiently. In this study, spectrally encoded (spread-time) code division multiple access (SE-CDMA) scheme is proposed as a flexible and adaptable technique for physical layer of cognitive relay networks. All primary and secondary users transmit their signals to a common base station (BS) and then the BS selects one of the cognitive secondary users based on feedback information to relay the primary user's (PU's) data. To study the efficiency of the system, two scenarios are considered. In the first scenario, the secondary users transmit their information using the... 

    Layeredcast - A hybrid peer-to-peer live layered video streaming protocol

    , Article 2010 5th International Symposium on Telecommunications, IST 2010, 4 December 2010 through 6 December 2010 ; 2010 , Pages 663-668 ; 9781424481835 (ISBN) Moshref, M ; Motamedi, R ; Rabiee, H. R ; Khansari, M ; Sharif University of Technology
    Peer-to-Peer overlay networks are an attractive foundation for video streaming. However, live Peer-to-Peer media streaming systems face many challenges such as bandwidth heterogeneity, node churn, and selfish nodes. Although many tree based and mesh based streaming protocols have been proposed, each has its own drawbacks such as unreliability and unfairness in tree based and long startup delay and complex scheduling in mesh based protocols. In this paper, we propose a new video streaming protocol called LayeredCast main features of which are: 1) Hybrid: Drawbacks of the simple approaches are compensated using a hybrid of mesh and tree overlays. 2) Layered Video: Provides an adaptive scheme... 

    Towards performance evaluation of mobile ad hoc network protocols

    , Article Proceedings - International Conference on Application of Concurrency to System Design, ACSD, 21 June 2010 through 25 June 2010, Braga ; 2010 , Pages 85-92 ; 15504808 (ISSN) ; 9780769540665 (ISBN) Ghassemi, F ; Movaghar, A ; Fokkink, W ; Sharif University of Technology
    We present a formal framework to evaluate stochastic properties of MANET protocols. It captures the interplay between stochastic behavior of protocols deployed at different network layers, and the underlying dynamic topology. The link connectivity model, which implicitly models node mobility, specifies link up and down lifetimes. We use so-called constrained labeled multi-transition systems (CLMSs) to specify MANETs; transitions are annotated by network restrictions, capturing the topologies in which a transition is possible. A continuous Markov chain can be generated from a CLMS, to evaluate the performance of the corresponding MANET  

    A modified thermodynamic modeling of wax precipitation in crude oil based on PC-SAFT model

    , Article Fluid Phase Equilibria ; Volume 429 , 2016 , Pages 313-324 ; 03783812 (ISSN) Mashhadi Meighani, H ; Ghotbi, C ; Jafari Behbahani, T ; Sharif University of Technology
    Elsevier  2016
    Wax precipitation may occur in production or transportation of crude oil form field which is a serious problem in petroleum industry. Flow assurance issues concerning wax precipitation make it necessary to develop a precise thermodynamic model to predict the wax appearance temperature and amount of precipitation at different conditions. In this work a new procedure has been proposed to characterize crude oil based on the SARA test considering the wax and asphaltene as single pseudo components. Two scenarios have been investigated for the survey of the crude oil characterization, with and without asphaltene pseudo component. Also, in this work, the Perturbed Chain form of the Statistical... 

    Quality of service in the network layer of vehicular Ad hoc networks

    , Article 2016 World Congress on Engineering and Computer Science, WCECS 2016, 19 October 2016 through 21 October 2016 ; Volume 2225 , 2016 , Pages 114-118 ; 20780958 (ISSN); 9789881404718 (ISBN) Tabar, S ; Najjar, L ; Gholamalitabar, M ; Sharif University of Technology
    Newswood Limited  2016
    Vehicular Ad-hoc Networks (VANET) has attracted a great deal of attention during the last decade. This type of wireless network is predicted to play a key role in future automotive innovation. VANET as a foundation for Intelligent Transportation System (ITS) promises many improvements in terms of safety, resource efficiency and passenger assistance services. Among these three main categories, safety applications are the most important ones because they deal with the lives of large numbers of people who drive every day. Safety applications are classified as real-time applications; they must act within a certain period of time, otherwise their implementation will be worthless. As a result,... 

    A survey of key pre-distribution and overlay routing in unstructured wireless networks

    , Article Scientia Iranica ; Volume 23, Issue 6 , 2016 , Pages 2831-2844 ; 10263098 (ISSN) Gharib, M ; Yousefi'zadeh, H ; Movaghar, A ; Sharif University of Technology
    Sharif University of Technology  2016
    Unstructured wireless networks such as mobile ad hoc networks and wireless sensor networks have been rapidly growing in the past decade. Security is known as a challenging issue in such networks, in which there is no fixed infrastructure or central trusted authority. Further, node limitations in processing power, storage, and energy consumption add further complexity to addressing security in such networks. While cryptography has proven to be an effective solution capable of satisfying most network security requirements, it requires the use of efficient key pre-distribution algorithms compatible with the limitation of unstructured wireless networks. Typically, a key pre-distribution... 

    Secure overlay routing using key pre-distribution: A linear distance optimization approach

    , Article IEEE Transactions on Mobile Computing ; Volume 15, Issue 9 , 2016 , Pages 2333-2344 ; 15361233 (ISSN) Gharib, M ; Yousefi'zadeh, H ; Movaghar, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Key pre-distribution algorithms have recently emerged as efficient alternatives of key management in today's secure communications landscape. Secure routing techniques using key pre-distribution algorithms require special algorithms capable of finding optimal secure overlay paths. To the best of our knowledge, the literature of key pre-distribution systems is still facing a major void in proposing optimal overlay routing algorithms. In the literature work, traditional routing algorithms are typically used twice to find a NETWORK layer path from the source node to the destination and then to find required cryptographic paths. In this paper, we model the problem of secure routing using... 

    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... 

    A novel genetic-based resource allocation and cooperative node selection technique for physical layer security designs

    , Article Wireless Personal Communications ; Volume 95, Issue 4 , 2017 , Pages 4733-4746 ; 09296212 (ISSN) Okati, N ; Mosavi, M. R ; Behroozi, H ; Sharif University of Technology
    Springer New York LLC  2017
    This paper presents a novel approach for power allocation and cooperative node selection to enhance physical layer security in presence of an eavesdropper in a wireless network. Our network consists of a source–destination pair and a number of cooperative nodes which can be used as relays to increase throughput at the destination, or as friendly jammers to confuse eavesdropper. First, we introduce a low complexity method, for which relay−jammer selection and power allocation are performed, simultaneously. Then, we propose self-adaptive genetic algorithm to solve the non-linear non-convex programing problem. Using the proposed method, the number of friendly jammers that ensure the secrecy... 

    A genetic approach in relay-jammer selection and power allocation for physical layer security

    , Article 8th International Symposium on Telecommunications, IST 2016, 27 September 2016 through 29 September 2016 ; 2017 , Pages 374-379 ; 9781509034345 (ISBN) Okati, N ; Mosavi, M. R ; Behroozi, H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    Node cooperation approaches improve physical layer security in wireless networks without applying data encryption. Selecting the appropriate nodes to cooperate as relays or friendly jammers, to degrade eavesdropper's link, is a challenging problem which has attracted a lot of attention in recent years. Various approaches, based on conventional exhaustive search, have been suggested for optimal relay-jammer selection and power allocation in the literature. The complexity of these methods is proportional to the number of intermediate nodes. As the number of intermediate nodes exceeds a specific bound, conventional exhaustive search appears infeasible due to high computational complexity. In... 

    Physical layer security in AF and CF relay networks with RF-energy harvesting

    , Article 2017 14th International ISC (Iranian Society of Cryptology) Conference on Information Security and Cryptology, ISCISC 2017, 6 September 2017 through 7 September 2017 ; 2018 , Pages 86-92 ; 9781538665602 (ISBN) Soleimani, A ; Mirmohseni, M ; Aref, M. R ; Sharif University of Technology
    In this paper, we investigate the achievable secrecy rate in a relay channel where the source and the destination wish to keep the information confidential from an untrusted relay (potential eavesdropper). The relay has no energy supply, and harvests its required energy for relaying from its received signals. For radio-frequency (RF) Energy Harvesting (EH) at the relay, we adopt power splitting (PS) approach. We study the problem of achieving positive secrecy rates between the transmitter and the receiver while making use of an untrusted relay. Energy limitation at the relay makes the problem more interesting. Because, the relay must choose either to eavesdrop the signal to be able to decode...