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mobile-telecommunication-systems
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Power allocation and relay selection for network-coded D2D communication underlay heterogeneous cellular networks
, Article Telecommunication Systems ; Volume 67, Issue 4 , April , 2018 , Pages 699-715 ; 10184864 (ISSN) ; Shayesteh, M. G ; Sharif University of Technology
Springer New York LLC
2018
Abstract
Underlay device-to-device (D2D) communication is an attractive technology enabling nearby cellular users to communicate with each other directly in order to increase data rate and spectral efficiency. The current cellular heterogeneous networks consist of macrocell base stations and small cell base stations with different transmit powers and coverage areas. Femtocell is the most popular small cell which is expected to be utilized in dense and ultra-dense scenarios in the future. Network coding in relay-assisted multi-hop communications improves achievable transmission rate and coverage of D2D communications. In this paper, two-hop random linear network coding network in cooperative D2D...
Flopcoin: a cryptocurrency for computation offloading
, Article IEEE Transactions on Mobile Computing ; Volume 17, Issue 5 , 2018 , Pages 1062-1075 ; 15361233 (ISSN) ; Ahmadi, M ; Kosta, S ; Hui, P ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
During the last years, researche'rs have proposed solutions to help smartphones improve execution time and reduce energy consumption by offloading heavy tasks to remote entities. Lately, inspired by the promising results of message forwarding in opportunistic networks, many researchers have proposed strategies for task offloading towards nearby mobile devices, giving birth to the Device-to-Device offloading paradigm. None of these strategies, though, offers any mechanism that considers selfish users and, most importantly, that motivates and defrays the participating devices who spend their resources. In this paper, we address these problems and propose the design of a framework that...
QoS-based multi-criteria handoff algorithm for femto-macro cellular networks
, Article Wireless Personal Communications ; Volume 98, Issue 1 , 2018 , Pages 1435-1460 ; 09296212 (ISSN) ; Jafarpour Alamdari, S ; Shayesteh, M. G ; Solouk, V ; Sharif University of Technology
Springer New York LLC
2018
Abstract
The hierarchical coexistence of femtocells and macrocells is a promising approach for heterogeneous networks (HetNets), dealing mainly with indoor coverage issues and providing high data rates in cellular networks. As for any HetNet, mobility management with handoff issues on top, should be studied prior to hindering the successful deployment of these networks. The current study introduces a new handoff algorithm in hierarchical macro/femtocell HetNets based on the combination of quality of service metrics for efficient network selection including: received signal strength, co-channel interference level, and outage probability of each of femtocell and macrocell networks. The proposed...
Robust parameter design using the weighted metric method-the case of 'the smaller the better'
, Article International Journal of Applied Mathematics and Computer Science ; Volume 19, Issue 1 , 2009 , Pages 59-68 ; 1641876X (ISSN) ; Noorossana, R ; Akhavan Niaki, T ; Lahijanian, H ; Sharif University of Technology
2009
Abstract
In process robustness studies, it is desirable to minimize the influence of noise factors on the system and simultaneously determine the levels of controllable factors optimizing the overall response or outcome. In the cases when a random effects model is applicable and a fixed effects model is assumed instead, an increase in the variance of the coefficient vector should be expected. In this paper, the impacts of this assumption on the results of the experiment in the context of robust parameter design are investigated. Furthermore, two criteria are considered to determine the optimum settings for the control factors. In order to better understand the proposed method and to evaluate its...
A new routing algorithm for sparse vehicular AD HOC networks with moving destinations
, Article 2009 IEEE Wireless Communications and Networking Conference, WCNC 2009, Budapest, 5 April 2009 through 8 April 2009 ; 2009 ; 15253511 (ISSN); 9781424429486 (ISBN) ; Ashtian, F ; Sharif University of Technology
2009
Abstract
In this paper, we propose the Object Pursuing based Efficient Routing Algorithm (OPERA) suitable for vehicular ad hoc networks (VANETs), esp. in sparse situations. The proposed algorithm is applicable for both moving and fixed destinations. It is based on considering static nodes at each intersection. In this algorithm, we optimize the decision making at intersections, with respect to the connectivity and feasibilty of the roads. To this end, we consider the average delay of each road as the connectivity metric, and the vehicle availability in the transmission range of the intersection as the feasibility metric. By exploiting the related metrics, we select the next road to forward the packet...
Secrecy throughput maximization for full-duplex wireless powered IOT networks under fairness constraints
, Article IEEE Internet of Things Journal ; Volume 6, Issue 4 , 2019 , Pages 6964-6976 ; 23274662 (ISSN) ; Sun, S ; Kang, X ; Guan, Y. L ; Pakravan, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, we study the secrecy throughput of a full-duplex wireless powered communication network (WPCN) for Internet of Things (IoT). The WPCN consists of a full-duplex multiantenna base station (BS) and a number of sensor nodes. The BS transmits energy all the time, and each node harvests energy prior to its transmission time slot. The nodes sequentially transmit their confidential information to the BS, and the other nodes are considered as potential eavesdroppers. We first aim to optimize the sum secrecy throughput of the nodes. The optimization variables are the duration of the time slots and the BS beamforming vectors in different time slots. The optimization problem is shown to...
Cache-Aided interference management in wireless cellular networks
, Article IEEE Transactions on Communications ; Volume 67, Issue 5 , 2019 , Pages 3376-3387 ; 00906778 (ISSN) ; Maddah Ali, M. A ; Salman Avestimehr, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
We consider the problem of interference management in wireless cellular networks with caches at both base stations and receivers, and we characterize the degrees of freedom (DoFs) per cell to within an additive gap of (1/3) and a multiplicative gap of 2 for all system parameters, under one-shot linear schemes. Our result indicates that the one-shot linear DoF per cell scales linearly with the total amount of cache available in the cell, i.e., the sum of the caches at the central base station and all the receivers within the cell, resembling a similar phenomenon previously observed for the case of fully connected wireless networks. To establish the result, we propose a decentralized and...
Relay selection for multi-source network-coded D2D multicast communications in heterogeneous networks
, Article Wireless Networks ; Volume 26, Issue 8 , 2020 , Pages 6059-6076 ; Shayesteh, M. G ; Sharif University of Technology
Springer
2020
Abstract
Multicast service is considered as a useful transmission mode for future mobile social services to deliver the traffic to multiple mobile users simultaneously. Device-to-device (D2D) multicast communication enables multiple proximate users to share the contents of their common interests directly. This paper aims to present a relay selection scheme for multi-source network-coded D2D multicast communication underlying heterogeneous cellular network which consists of macrocells and femtocells. We propose two methods for selecting efficient relays from the set of femtocell base stations (FBSs). The first method, named destination-blind relay selection, identifies those idle FBSs that can...
A dual circularly reconfigurable polarization patch antenna for fifth generation mobile communication systems
, Article Progress In Electromagnetics Research C ; Volume 105 , 2020 , Pages 73-84 ; Nouri, M ; Aghdam, S. A ; Zia, M. T ; Harb, B ; Jafarieh, A ; Sharif University of Technology
Electromagnetics Academy
2020
Abstract
In this paper, a reconfigurable patch antenna with Circular Polarization (CP) diversity with theoretical discussion and verification is proposed for fifth generation (5G) of mobile communication systems. The proposed antenna contains two PIN diodes, which are correctly placed on the ground plane to obtain polarization diversity. By switching between two ON/OFF modes in the PIN diodes, the proposed antenna can support either the RHCP mode or the LHCP mode. An antenna with the well-matched impedance bandwidths (S11 ≤ −10 dB) of 2.5 GHz (27 ∼ 29.5 GHz) and 3 GHz (36 ∼ 39 GHz) and the dual-band 3-dB axial ratios of 6% (27.3–29 GHz) and 8.4% (35–38.2 GHz) operates in both the RHCP and LHCP modes....
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, S ; Sharif University of Technology
2008
Abstract
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
CEBAC: A decentralized cooperation enforcement based access control framework in MANETs
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 427-434 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Mashayekhi, H ; Movaghar, A ; Jalili, R ; Sharif University of Technology
2008
Abstract
Prevention of unauthorized access to services in mobile ad hoc networks is a more sophisticated problem than access control in other networks, due to interconnection facilities and lack of any fixed network infrastructure in such networks. Therefore regarding the nature of these networks, controlling access to services should be in a decentralized manner providing good performance and preserving network security. In this paper, we propose a decentralized Cooperation Enforcement Based Access Control (CEBAC) framework for mobile ad hoc networks. CEBAC comprises several groups of Service Authorizers, each issuing Credentials for access to a specific kind of services. The User Authorization for...
An anti-SMS-spam using CAPTCHA
, Article ISECS International Colloquium on Computing, Communication, Control, and Management, CCCM 2008, Guangzhou, 3 August 2008 through 4 August 2008 ; Volume 2 , 2008 , Pages 318-321 ; 9780769532905 (ISBN) ; Shirali Shahreza, M ; Sharif University of Technology
2008
Abstract
Today sending spams has turned to be a major problem in the Internet. In last 20 years, the Internet and mobile communication growth in parallel. So the spams are also born on the mobile phones as the form of SMS (Short Message Service) spams. In this paper a new method is proposed for filtering SMS spams using CAPTCHA (Completely Automatic Public Turing Test to Tell Computer and Human Apart) systems. CAPTCHA systems are used to distinguish between human users and computer programs automatically. In this method, the picture of an object is sent as an SMS picture message. Also name of that object and name of three other objects are written in the SMS as a multiple-choose question. The user...
Symmetric relaying strategy for two-relay networks
, Article IEEE Communications Letters ; Volume 12, Issue 10 , 2008 , Pages 708-710 ; 10897798 (ISSN) ; Aref, M. R ; Sharif University of Technology
2008
Abstract
In this paper, we propose a concept of relaying named symetric relaying strategy for two relay network. In our strategy, we have two relays in the network and both relays can completely decode the message transmitted by the other relay. The proposed rate is shown to subsume the previously proposed rate for feed-forward relay network based on decodeand- forward. © 2008 IEEE
Approximation of a confidence interval for link distances in mobile ad hoc networks
, Article 3rd IEEE/Create-Net International Conference on Communication System Software and Middleware, COMSWARE, Bangalore, 6 January 2008 through 10 January 2008 ; 2008 , Pages 520-527 ; 9781424417971 (ISBN) ; Sepehri, M. M ; Sharifyazdi, M ; Sharif University of Technology
IEEE Computer Society
2008
Abstract
A Mobile Ad Hoc Network (MANET) is an infrastructure-less network composed of mobile devices. In order to meet the foresight of newly developing MANETs, a method of maintaining a real-time flow despite dynamic topology and random movement of users is required. Mobility prediction is one of the keys to successful design of efficient protocols to find stable and reliable routes in MANETs. An important characteristic of a MANET is the distribution of the link distance between communicating users. In this paper a novel mobility model is developed for users of a MANET wandering in an unlimited area and is used to derive an analytical framework to approximate the communication links distance...
Leader connectivity management and flocking velocity optimization using the particle swarm optimization method
, Article Scientia Iranica ; Vol. 19, Issue 5 , 2012 , pp. 1251-1257 ; ISSN: 10263098 ; Vatankhah, R ; Alasty, A ; Vossough,i G. R ; Boroushaki M ; Sharif University of Technology
Abstract
Flocking through leader following structures in mobile networks raises attractive control problems. Due to limited sensing radii, leaders locally influence a network of agents. In this paper, we consider the problem of real-time maximization of flocking velocity. By using local information and a Particle-Swarm-Optimization (PSO) algorithm, a Leader Agent (LA) actively motivates flocking at high speed. The LA manages topology of the network in its neighborhood and increases flocking velocity. PSO output quality and calculation costs show that the proposed optimization algorithm is practically feasible. A case-study is also presented
Adaptive handover algorithm in heterogeneous femtocellular networks based on received signal strength and signal-to-interference-plus-noise ratio prediction
, Article IET Communications ; Volume 8, Issue 17 , 27 November , 2014 , Pages 3061-3071 ; ISSN: 17518628 ; Yousefi, S ; Shayesteh, M. G ; Sharif University of Technology
Abstract
In this study, an efficient handover algorithm based on the received signal strength (RSS) prediction is presented for two-tier macro-femtocell networks in which, because of the fading effects of channel and short coverage range of femtocells, ping-pong handovers may take place. In the proposed approach, first each mobile station (MS) uses the recursive least square algorithm for predicting the RSS from the candidate base stations (BSs) including both femtocell and macrocell BSs. Then, according to the predicted RSS values, several future values of signal-to-interference plus noise ratio (SINR) are calculated. Afterwards, the candidate list of BSs is pruned according to the estimated future...
Leader connectivity management and flocking velocity optimization using the particle swarm optimization method
, Article Scientia Iranica ; Volume 19, Issue 5 , 2012 , Pages 1251-1257 ; 10263098 (ISSN) ; Vatankhah, R ; Alasty, A ; Vossoughi, G. R ; Boroushaki, M ; Sharif University of Technology
2012
Abstract
Flocking through leader following structures in mobile networks raises attractive control problems. Due to limited sensing radii, leaders locally influence a network of agents. In this paper, we consider the problem of real-time maximization of flocking velocity. By using local information and a Particle-Swarm-Optimization (PSO) algorithm, a Leader Agent (LA) actively motivates flocking at high speed. The LA manages topology of the network in its neighborhood and increases flocking velocity. PSO output quality and calculation costs show that the proposed optimization algorithm is practically feasible. A case-study is also presented
Adaptive power control algorithms in underwater wireless optical CDMA cellular networks
, Article 2015 4th International Workshop on Optical Wireless Communications, IWOW 2015, 7 September 2015 through 10 September 2015 ; September , 2015 , Pages 107-111 ; 9781467377263 (ISBN) ; Akhoundi, F ; Salehi, J. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In this paper we introduce two adaptive power control algorithms for downlink of underwater wireless optical cellular networks. The first approach is based on the angle of user's position with respect to optical base transceiver station (OBTS) of the cell. The second scheme works according to the link distance between the user and the OBTS. Defining an optimization problem, we aim to guaranty the quality of service for each user while minimizing the transmitting power. In our methods, we utilize limited feedback channel state information (CSI) so that the algorithm could be implemented with low complexity. The simulation results for different water types demonstrate that our proposed...
Joint reliable and power-efficient CDS-based topology control for wireless multi-hop networks
, Article Communications in Computer and Information Science, 26 June 2010 through 28 June 2010, Ankara ; Volume 84 , 2010 , Pages 327-337 ; 18650929 (ISSN) ; 9783642141706 (ISBN) ; Yassaei, M ; Ejlali, A ; Rabiee, H. R ; Esmaeelzadeh, V ; Sharif University of Technology
Abstract
High reliability and low power consumption are the critical objectives in wireless networks and the network topology is an effective issue in these objectives. This paper investigates these two objectives in the wireless multi-hop networks simultaneously. For this purpose, a connected dominating set CDS-based topology control approach is proposed. In this approach a distributed topology control algorithm with different power adjustment measures is suggested. Our goal is to self-organize this network with minimum interference and power consumption subject to connectivity preservation. Unlike many reliability enhancement algorithms, the proposed mechanism does not compromise power consumption....
Multilingual highlighting CAPTCHA
, Article Proceedings - 2011 8th International Conference on Information Technology: New Generations, ITNG 2011, 11 April 2011 through 13 April 2011, Las Vegas, NV ; 2010 , Pages 447-452 ; 9780769543673 (ISBN) ; Shirali Shahreza, M ; Sharif University of Technology
2010
Abstract
There are many websites specially designed for mobile phones. Some hackers write automated programs to abuse these website services and waste the website resources. Therefore, it is necessary to distinguish between human users and computer programs. Methods known for achieving this are known as CAPTCHA (Completely Automated Public Turing test to tell Computers and Human Apart). CAPTCHA methods are mainly based on the weaknesses of OCR (Optical Character Recognition) systems and ask the user to type a word. So using them is difficult in tools such as PDAs (Personal Digital Assistant) or mobile phones that lack a complete keyboard. In this paper, a new CAPTCHA system is proposed for...