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    Preventing the transmission of harmful cognitive radio users in the presence of primary users

    , Article Proceedings - 2009 1st UK-India International Workshop on Cognitive Wireless Systems, UKIWCWS 2009, 11 December 2009 through 12 December 2009, New Delhi ; 2009 ; 9781457701832 (ISBN) Fathollahi, M ; Soleimanipour, M ; Sharif University of Technology
    Abstract
    A cognitive radio provides access to a licensed spectrum for unlicensed users opportunistically provided that they are not harmful for licensed users (primary users). We call a cognitive radio user (CR user) harmful, when it generates interference for primary users (PU) or occupies spectrum holes excessively. This paper discusses the spectrum management policy against harmful CR users. For this, we design a jammer signal which ruins transmission of harmful CR users and forces them to leave the spectrum without damaging the communication of PUs. This signal is designed using group subspace technique for both synchronous and asynchronous channels. Our simulation results show that the designed... 

    Trust modeling based on Capra cognitive framework

    , Article Procedia - Social and Behavioral Sciences ; Volume 32 , 2012 , Pages 197-203 ; 18770428 (ISSN) Mirzaie, K ; Fesharaki, M. N ; Daneshgarb, A ; Sharif University of Technology
    2012
    Abstract
    Trust is needed to facilitate cooperation and delegation among agents in a multi-agent system. This paper proposes a trust model based on Capra cognitive framework. This framework explains social phenomena from the four perspectives of structure (agent), pattern (network), process, and meaning. We assume trust as "meaning" in the proposed model. Every agent has properties such as personality, responsibility, and specialty. Interaction among agents is based on friendship network. OODA, as a general process for decision making, is used for updating the trust in the simulation run  

    On The Foundation of Cognitive Sciences: A Critique of Neurotheology

    , M.Sc. Thesis Sharif University of Technology Solgi, Farshid (Author) ; Hosseini, Hassan (Supervisor)
    Abstract
    One of the tasks of philosophy of science is to study the pre-suppositions involved in the natural sciences, to study the concepts used in scientific researches and theorizing. Hence, neglecting philosophy and even the modality of philosophical views, can have devastating effects on any science, including psychology (if it can be called science). Wittgenstein believed that in psychology we are confronted with experimental methods and conceptual confusion, and that this confusion does not go away with giving the title of young knowledge to the psychology. The emergence and dominance of behaviorism can be attributed to the effects of positivism and the uncomprehensive interpretation of physics... 

    A new outer bound for a class of interference channels with a cognitive relay and a certain capacity result

    , Article IEEE Communications Letters ; Volume 17, Issue 2 , 2013 , Pages 241-244 ; 10897798 (ISSN) Charmchi, H ; Hodtani, G. A ; Nasiri Kenari, M ; Sharif University of Technology
    2013
    Abstract
    The interference channel with a cognitive relay is a variation of the classical two-user interference channel in which a relay aids the transmission among the users. The relay is assumed to have genie-aided cognition: that is it has full, a-priori, knowledge of the messages to be transmitted. We obtain a new outer bound for this channel model and prove capacity for a class of channels in which the transmissions of the two users are non interfering. This capacity result improves on a previous result for the Gaussian case in which the capacity was proved to within a gap of 3 bits/s/Hz  

    Three-user cognitive interference channel: Capacity region with strong interference

    , Article IET Communications ; Volume 6, Issue 13 , 2012 , Pages 2099-2107 ; 17518628 (ISSN) Mirmohseni, M ; Akhbari, B ; Aref, M. R ; Sharif University of Technology
    IET  2012
    Abstract
    This study investigates the capacity region of a three-user cognitive radio network with two primary users and one cognitive user. A three-user cognitive interference channel (C-IFC) is proposed by considering a three-user interference channel (IFC) where one of the transmitters has cognitive capabilities and knows the messages of the other two transmitters in a non-causal manner. First, two inner bounds on the capacity region of the three-user C-IFC are obtained based on using the schemes which allow all receivers to decode all messages with two different orders. Next, two sets of conditions are derived, under which the capacity region of the proposed model coincides with the capacity... 

    Opportunistic spectral access in cooperative cognitive radio networks

    , Article IEEE Vehicular Technology Conference ; 14-17 September , 2014 ; ISSN: 15502252 ; ISBN: 9781479944491 Liang, W ; Ng, S. X ; Bayat, S ; Li, Y ; Hanzo, L ; Sharif University of Technology
    Abstract
    A pragmatic distributed algorithm (PDA) is proposed for supporting the ef-cient spectral access of multiple Primary Users (PUs) and Cognitive Users (CUs) in cooperative Cognitive Radio (CR) networks. The CUs may serve as relay nodes for relaying the signal received from the PUs to their destinations, while both the PUs' and the CUs' minimum rate requirements are satis-ed. The key idea of our PDA is that the PUs negotiate with the CUs concerning the speci-c amount of relaying and transmission time, whilst reducing the required transmission power or increasing the transmission rate of the PU. Our results show that the cooperative spectral access based on our PDA reaches an equilibrium, when it... 

    Towards a holistic view of humanities

    , Article International Journal of the Humanities ; Volume 9, Issue 5 , 2011 , Pages 247-256 ; 14479508 (ISSN) Khosravizadeh, P ; Gohari, O ; Gohari, N ; Ghaziani, G ; Sharif University of Technology
    Abstract
    The paper investigates the deep structure of the human mind by analyzing multiple intelligences theory. Regarding serious critiques proposed by a number of cognitive neuroscientists, psychologists, philosophers, and educational theorists (i.e. Sternberg 1983, 1991; Eysenck 1994; Scarr 1985; Klein 1998; Demetriou and Kazi 2006; Demetriou, Mouyi, and Spanoudis 2010, among others), it seems that the different types of intelligence introduced by Gardner (1983) have a shared feature. The authors believe that this particular shared feature can be counted as the key point of the underlying system of human knowledge. Since human cognition may be analyzed by means of universal structures of the mind,... 

    A location privacy-preserving method for spectrum sharing in database-driven cognitive radio networks

    , Article Wireless Personal Communications ; Volume 95, Issue 4 , 2017 , Pages 3687-3711 ; 09296212 (ISSN) Salami, Z ; Ahmadian Attari, M ; Jannati, H ; Aref, M. R ; Sharif University of Technology
    Springer New York LLC  2017
    Abstract
    The great attention to cognitive radio networks (CRNs) in recent years, as a revolutionary communication paradigm that aims to solve the problem of spectrum scarcity, prompts serious investigation on security issues of these networks. One important security concern in CRNs is the preservation of users location privacy, which is under the shadow of threat, especially in database-driven CRNs. To this end, in this paper, we propose a Location Privacy Preserving Database-Driven Spectrum-Sharing (L-PDS 2) protocol for sharing the spectrum between PUs and SUs in a database-driven CRN, while protecting location privacy of both primary and secondary users, simultaneously. We also present two... 

    Cognitive memory comparison between tinnitus and normal cases using event-related potentials

    , Article Frontiers in Integrative Neuroscience ; Volume 12 , 2018 ; 16625145 (ISSN) Asadpour, A ; Alavi, A ; Jahed, M ; Mahmoudian, S ; Sharif University of Technology
    Frontiers Media S.A  2018
    Abstract
    About 20 percent of people above 60 years old suffer from tinnitus though no definitive treatment has been found for it. Evaluation of electrical brain activity using Event-Related Potentials (ERPs) is one of the methods to investigate the underlying reasons of tinnitus perception. Previous studies using ERPs suggest that the precognitive memory in tinnitus groups is negatively affected in comparison to the normal hearing groups. In this study, cognitive memory has been assessed using visual and auditory P300 response with oddball paradigm. Fifteen chronic tinnitus subjects and six normal hearing subjects participated in the experiment. T-test with significance level of 0.05 was applied on... 

    Spectrally encoded code-division multiple access for cognitive radio networks

    , Article IET Communications ; Vol. 8, Issue. 2 , 2014 , Pages 184-196 ; ISSN: 17518628 Najafi, S ; Shayesteh, M. G ; Sharif University of Technology
    Abstract
    Recent studies have revealed that spectrum congestion is due to the inefficient usage of spectrum against the availability. Cognitive radio is viewed as an approach for improving the utilisation of radio spectrum. The spectrally encoded (spread-time) code-division multiple access (SE-CDMA) technique (which is regarded as the dual of spread spectrum CDMA) is considered and its performance in cognitive radio networks is studied. In cognitive network spectrum, overlay and underlay techniques are employed to enable the primary and secondary users to coexist while improving the overall spectrum efficiency. It is shown that SE-CDMA provides considerable flexibility to design overlay and underlay... 

    Degrees of freedom in a three-user cognitive interference channel

    , Article 2013 Iran Workshop on Communication and Information Theory ; May , 2013 , Page(s): 1 - 6 ; 9781467350235 (ISBN) Shakeri, Z ; Chaghooshi, A. F ; Mirmohseni, M ; Aref, M. R ; Sharif University of Technology
    2013
    Abstract
    We study the degrees of freedom of the three-user Gaussian interference channel under the circumstance where one or more transmitters are non-causally cognitive, meaning they are aware of the messages of one or more transmitters in a non-causal manner. Our focus is on the total degrees of freedom of the three-user cognitive interference channel. Our first case is when only one of the transmitters is fully cognitive and knows the messages of the other users. We prove that using interference alignment and interference cancellation, the achievable total degrees of freedom is 11/6 and does not coincide with the calculated total degrees of freedom upper bound which is 2. In the second and third... 

    Cognitive radio networks spectrum allocation: An ACS perspective

    , Article Scientia Iranica ; Volume 19, Issue 3 , 2012 , Pages 767-773 ; 10263098 (ISSN) Koroupi, F ; Talebi, S ; Salehinejad, H ; Sharif University of Technology
    2012
    Abstract
    Cognitive Radio (CR) is a promised solution to the lack of spectrum, as well as spectrum inefficiency, in current communication networks. A major demand of this technology is for fair spectrum assignment to unlicensed (secondary) users. This paper addresses a new approach to this challenge in CR networks, based on the Graph Coloring Problem (GCP) and the Ant Colony System (ACS). In addition, we compare the performance of the proposed algorithm with Color Sensitive Graph Coloring (CSGC) and Particle Swarm Optimization (PSO) based techniques  

    A new spectrum sensing circuit for cognitive radio applications

    , Article Proceedings - CIMSim 2011: 3rd International Conference on Computational Intelligence, Modelling and Simulation, 20 September 2011 through 22 September 2011, Langkawi ; 2011 , Pages 404-407 ; 9780769545622 (ISBN) Vahidpoor, Z ; Forooraghi, K ; Atlasbaf, Z ; Ahmadi, A. F ; Sharif University of Technology
    2011
    Abstract
    Fast, accurate and efficient sensing is of important aspects in cognitive radio technology. A new sensing circuit is proposed using a phase frequency detector for cognitive radio applications. Using this method, spectral sensing can be done in a very short time by a low cost, low power circuit, compared with available implemented methods. The PFD circuit resolves different frequencies without the need of variable filter bandwidth or the banks of filters. Also it accelerates sensing procedure because of short time needed to detect the signal. Simulations show the accurate operation of this method and comparison with other methods shows faster sweep rates  

    Capacity bounds for the three-user Cognitive Z-Interference Channel

    , Article 12th Canadian Workshop on Information Theory, CWIT 2011, 17 May 2011 through 20 May 2011 ; May , 2011 , Pages 34-37 ; 9781457707438 (ISBN) Mirmohseni, M ; Akhbari, B ; Aref, M. R ; Sharif University of Technology
    2011
    Abstract
    In this paper, we consider a three-user cognitive radio network with two primary users and one cognitive radio. We concentrate on a three-user Interference Channel (IFC) where one of the transmitters has cognitive capabilities and non-causally knows the messages of the other two transmitters. Moreover, we assume that the cognitive transmitter does not cause any interference at the receivers of the primary users and we introduce three-user Cognitive Z-Interference Channel (C-ZIFC). We first obtain an inner bound on the capacity region of three-user C-ZIFC, where our coding scheme makes use of collaborative strategy by rate splitting and cooperative strategy by superposition coding. Moreover,... 

    Interference efficiency: A new concept to analyze the performance of cognitive radio networks

    , Article 2017 IEEE International Conference on Communications Workshops, ICC Workshops 2017, 21 May 2017 through 25 May 2017 ; 2017 , Pages 1105-1110 ; 9781509015252 (ISBN) Mili, M. R ; Musavian, L ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    Abstract
    In this paper, we develop and analyze a novel performance metric, called interference efficiency (IE), that shows the number of transmitted bits per unit of interference energy imposed on the primary users (PUs) in an underlay cognitive radio network (CRN). Specifically, we develop a framework to maximize the IE of a CRN with multiple secondary users (SUs) while satisfying target constraints on the average interference power on PU receiver, total SUs transmit power and minimum ergodic rate for the SUs. In doing so, we formulate a multiobjective optimization problem (MOP), that aims to achieve the maximum ergodic sum rate of multiple SUs and the minimum average interference power on the... 

    Simultaneous Block Iterative Method with Adaptive Thresholding for Cooperative Spectrum Sensing

    , Article IEEE Transactions on Vehicular Technology ; Volume 68, Issue 6 , 2019 , Pages 5598-5605 ; 00189545 (ISSN) Azghani, M ; Abtahi, A ; Marvasti, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    The effective utilization of the spectrum has become an essential goal in the communications field, which is addressed by the Cognitive Radio (CR) systems. The primary task in a CR system is to sense the spectrum to identify its holes to be exploited by the secondary users. In this paper, we tackle the compressed spectrum sensing problem in a cooperative manner. The CRs distributed in an area take the samples of the signal that has been reached to them through a wireless fading channel. The spectrum has the block-sparse structure. Moreover, the spectrum observed by different CRs in an area share the same block-sparse support. Therefore, we suggest to exploit the joint block-sparsity... 

    Design and Investigation of the Impact of Using Virtual Reality Games on the Elderly’s Cognitive Impairments

    , M.Sc. Thesis Sharif University of Technology Jamei, Mohammad Moein (Author) ; Meghdari, Ali (Supervisor) ; Alemi, Minoo (Supervisor) ; Taheri, Alireza (Co-Supervisor)
    Abstract
    The process of aging is accompanied by problems that can affect the daily activities of an elderly. Recent studies have shown that the use of virtual reality technology provides a variety of diagnostic methods and clinical systems to prevent and delay cognitive aging to ensure the normal life of the elderly. In this project, efforts have been made to design some virtual reality-based games focusing on memory and recall in the form of three scenarios of finding address, finding car, and virtual-reality based maze game for the elderly to prevent cognitive decline and developing the dementia so that the difficulty of the game level ahead of each elderly can be adjusted according to his or her... 

    Multi-user opportunistic spectrum access with channel impairments

    , Article AEU - International Journal of Electronics and Communications ; Volume 67, Issue 11 , 2013 , Pages 955-966 ; 14348411 (ISSN) Majd, S. A ; Salehkaleybar, S ; Pakravan, M. R ; Sharif University of Technology
    2013
    Abstract
    In this paper, we study the impact of sensing error and channel fading on the decision process of a multiple secondary user network in a primary network whose channel occupancy states are modelled as a Bernoulli process. We present a randomized access strategy to maximize total secondary network throughput. The proposed method guarantees that the probability of collision between primary and secondary users in each channel is less than the predefined value of P c = ξ. To find the optimal access strategy, we formulate secondary network throughput as an optimization problem. Then, using the KKT method to find the solution, we break the original problem into multiple sub-problems. Then, we... 

    Optimal probabilistic initial and target channel selection for spectrum handoff in cognitive radio networks

    , Article IEEE Transactions on Wireless Communications ; Volume 14, Issue 1 , 2015 , Pages 570-584 ; 15361276 (ISSN) Sheikholeslami, F ; Nasiri Kenari, M ; Ashtiani, F ; Sharif University of Technology
    Abstract
    Spectrum mobility in cognitive radio networks not only enables the secondary users to guarantee the desired QoS of the primary users but also grants an efficient exploitation of the available spectrum holes in the network. In this paper, we propose a probabilistic approach in determining the initial and target channels for the handoff procedure in a single secondary user network. To characterize the network, a queuing theoretical framework is introduced, and 'stay' and 'change' handoff policies are both addressed. The performance of the secondary user in terms of average sojourn and extended service times for secondary connections is analyzed, and convex optimization problems with the... 

    Compress-and-forward strategy for causal cognitive interference channel

    , Article Proceedings 2010 IEEE International Conference on Information Theory and Information Security, ICITIS 2010, 17 December 2010 through 19 December 2010, Beijing ; 2010 , Pages 1088-1095 ; 9781424469406 (ISBN) Mirmohseni, M ; Akhbari, B ; Aref, M. R ; Sharif University of Technology
    2010
    Abstract
    In this paper, we consider Causal Cognitive Interference Channel (CC-IFC), wherein the cognitive user overhears the channel and exploits knowledge of the primary user's message from the causally received signals. We propose a coding scheme which combines Compress-and-Forward (CF) strategy with Marton coding with common information at the cognitive user. Rate splitting for messages at both transmitters is used to have a collaborative strategy. Moreover, the cognitive user compresses its channel observation using Wyner-Ziv coding and splits the index of its compressed signal. Then, the cognitive user having common information to both receivers and private information to each of them, jointly...