Search for: wireless-telecommunication-systems
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    Symbol error rate analysis and power allocation for decode and forward relaying with channel estimation error

    , Article 2012 19th International Conference on Telecommunications, , 23 April 2012 through 25 April 2012, Jounieh ; 2012 ; 9781467307475 (ISBN) Razavi, A ; Pakravan, M. R ; Sharif University of Technology
    IEEE  2012
    In this paper we study the statistical properties of the Signal to Noise Ratio (SNR) of the dual-hop relaying link in a cooperative wireless communication system in the presence of channel estimation errors for Decode and Forward (DF) relaying protocol. Then for assessment of the system performance the Symbol Error Rate (SER) is considered. Two approaches are introduced for SER calculation from which the second one results in a closed form solution. Finally the second approach is used to find an optimum power allocation scheme for transmission of pilot and data symbols at the source and the relay terminals that results in minimizing the SER and considerable amount of power saving. Also Monte... 

    Some comments on wireless sensor networks for natural hazards

    , Article ACWR 2011 - Proceedings of the International Conference on Wireless Technologies for Humanitarian Relief, 18 December 2011 through 21 December 2011 ; December , 2011 , Pages 315-322 Grado Caffaro, M. A ; Grado Caffaro, M ; Ebrahimi, M. S ; Sharif University of Technology
    Presently, the urgency of creating efficient system to tackle natural hazards such as tsunamis, earthquakes, landslides and floods to cite just a few, have originated that Wireless Sensor Networks (WSNs) play an increasingly important role in the natural hazards scenario as an efficient early warning system, sometimes in synergy with satellites-GMES (Global Monitoring Earth Systems) and also with mobile robotics. Their integration into the web scenario, giving rise to the sensor-web technology, provides even more power to the intrinsic strengths of WSNs. The WSNs application in post-disaster scenarios is also an emerging challenging issue. In this paper the fundamental technology concepts of... 

    A price-based optimal routing algorithm in Wireless Sensor Networks

    , Article 7th International Conference on Wireless Communications, Networking and Mobile Computing, WiCOM 2011, 23 September 2011 through 25 September 2011 ; September , 2011 , Page(s): 1 - 6 ; ISSN : 2161-9646 ; 9781424462520 (ISBN) Emamjomeh, M ; Arisian, B ; Sharif University of Technology
    Routing methods and algorithms in "Wireless Sensor Networks" attract researchers' attention a lot recently. In order to find the optimal path in WSNs depending on their type and application, various algorithms are proposed. In this paper, an optimal path finding algorithm based on "Game Theory" is discussed and improved. This algorithm finds a path witch is optimizing network lifetime, load distribution, and path reliability simultaneously  

    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  

    FiWi enhanced LTE-A HetNets with unreliable fiber backhaul sharing and WiFi offloading

    , Article Proceedings - IEEE INFOCOM, 26 April 2015 through 1 May 2015 ; Volume 26 , 2015 , Pages 1275-1283 ; 0743166X (ISSN) ; 9781479983810 (ISBN) Beyranvand, H ; Levesque, M ; Maier, M ; Salehi, J. A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    To cope with the unprecedented growth of mobile data traffic, we investigate the performance gains obtained from unifying coverage-centric 4G mobile networks and capacity-centric fiber-wireless (FiWi) broadband access networks based on data-centric Ethernet technologies with resulting fiber backhaul sharing and WiFi offloading capabilities. Despite recent progress on backhaul-aware 4G studies with capacity-limited backhaul links, the performance-limiting impact of backhaul latency and reliability has not been examined in sufficient detail previously. In this paper, we evaluate the maximum aggregate throughput, offloading efficiency, and in particular the delay performance of FiWi enhanced... 

    Sub-pixel image registration based on physical forces

    , Article 2010 International Conference on Wireless Communications and Signal Processing, WCSP 2010, 21 October 2010 through 23 October 2010, Suzhou ; 2010 ; 9781424475551 (ISBN) Ghayoor, A ; Ghorbani, S ; Beheshti Shirazi, A. A ; Sharif University of Technology
    A new method for image registration has been previously proposed by the authors, which the registration is based on physical forces. The registration parameters are translation and rotation. This method assumes images like charged materials that attract each other. In this case, one of the images moves in the same direction as the applied force while the other one is still. The movement of the image continues until the resultant force becomes zero. This approach estimates the registration parameters simultaneously and leading to a better optimized set of registration parameters. The registration error for this method is 1 to 3 pixels. In this paper we aim to develop this method for the... 

    A Game Theory approach for optimal routing: In Wireless Sensor Networks

    , Article 2010 6th International Conference on Wireless Communications, Networking and Mobile Computing, WiCOM 2010, 23 September 2010 through 25 September 2010 ; September , 2010 ; 9781424437092 (ISBN) Arisian, B ; Eshghi, K ; Sharif University of Technology
    In this paper, a "Game Theory" approach for finding an optimal path in a "Wireless Sensor Network" is discussed. WSN is one of the most interesting research fields in the communication networks, and is the center of attention in recent years. In our model, a pricing and payment technique is presented to obtain an optimal path in a WSN by considering reliability, energy and traffic load. The proposed algorithm is able to find a path which improves network lifetime, load distribution and path reliability  

    The direction of arrival estimation in DS-CDMA systems employing the code-matched filters and parallel ESPRIT algorithms

    , Article Proceedings - 2010 IEEE International Conference on Wireless Communications, Networking and Information Security, WCNIS 2010, 25 June 2010 through 27 June 2010, Beijing ; 2010 , Pages 274-279 ; 9781424458516 (ISBN) Samsami Khodadad, F ; Hoseini Karani, S. B ; Safaei, A ; Hadi Karami Ata, M ; Taheri, A ; Sharif University of Technology
    It was shown that the number of array elements must exceed the number of sources for subspace-based direction-of-arrival (DOA) estimation. But this is not practical for a direct-sequence code-division multiple access (DS-CDMA) wireless system, since the number of mobile users is very large. To remove the aforementioned restriction, a DOA estimator, employing the code-matched filters and parallel ESPRIT algorithms, is proposed. This algorithm does not use to search all angles such as MUSIC method. Besides, it is not necessary to use AIC and MDL criterion to estimate the number of sources in the proposed algorithm. Simulation results illustrates the appropriate performance of the new method  

    A game-theoretic approach for power allocation in bidirectional cooperative communication

    , Article IEEE Wireless Communications and Networking Conference, WCNC, 18 April 2010 through 21 April 2010 ; April , 2010 ; 15253511 (ISSN) ; 9781424463985 (ISBN) Janzamin, M ; Pakravan, M ; Sedghi, H ; Sharif University of Technology
    Cooperative communication exploits wireless broadcast advantage to confront the severe fading effect on wireless communications. Proper allocation of power can play an important role in the performance of cooperative communication. In this paper, we propose a distributed gametheoretical method for power allocation in bidirectional cooperative communication networks. In this work, we consider two nodes as data sources who want to cooperate in sending data to the destination. In addition to being data source, each source node has to relay the other's data. We answer the question: How much power each node contributes for relaying other node's data? We use Stackelberg game which is an... 

    Fuzzy mobility analyzer: A framework for evaluating mobility models in mobile ad-hoc networks

    , Article IEEE Wireless Communications and Networking Conference, WCNC, 18 April 2010 through 21 April 2010 ; April , 2010 ; 15253511 (ISSN) ; 9781424463985 (ISBN) Khaledi, M. J ; Rabiee, H. R ; Khaledi, M. H ; Sharif University of Technology
    Mobility is one of the most challenging issues in mobile ad-hoc networks and has a significant impact on performance of network protocols. Different kinds of mobility models have been proposed to represent the movement pattern of mobile nodes in mobile ad-hoc networks. These models attempt to capture various mobility characteristics existing in real movement of mobile nodes. In this paper, a new framework called Fuzzy Mobility Analyzer has been proposed to evaluate mobility models. At first, our framework categorizes mobility models based on their mobility characteristics into five classes; subsequently it uses mobility metrics to capture the mobility and graph connectivity characteristics... 

    Precision enhancement in ETSI-Hata propagation model tuning using experimental data in a dense urban area

    , Article International Journal of Communication Systems ; Volume 23, Issue 1 , 2010 , Pages 101-108 ; 10745351 (ISSN) Atamanesh, M ; Farzaneh, F ; Sharif University of Technology
    In this paper an enhanced ETSI-Hata propagation model tuning is presented. The three-dimensional (3D) digital terrain map (DTM) was included in the simulation process. For the enhancement of the model tuning process and precision verification of ETSI-Hata model, the real 3D map of the buildings of the simulated area was incorporated over the DTM. Multiple knife edge diffraction method and the antenna effective height method were used to calculate the diffraction loss. This method was applied for a real urban scenario. For every sector in the coverage area, a tuned model was exploited. Using a genetic algorithm, frequency planning for the entire urban area was performed, which resulted in an... 

    Characterizing terahertz channels for monitoring human lungs with wireless nanosensor networks

    , Article Nano Communication Networks ; Volume 9 , 2016 , Pages 43-57 ; 18787789 (ISSN) Zarepour, E ; Hassan, M ; Chou, C. T ; Ebrahimi Warkiani, M ; Sharif University of Technology
    Elsevier B.V  2016
    We characterize terahertz wireless channels for extracting data from nanoscale sensors deployed within human lungs. We discover that the inhalation and exhalation of oxygen and carbon dioxide causes periodic variation of the absorption coefficient of the terahertz channel. Channel absorption drops to its minimum near the end of inhalation, providing a window of opportunity to extract data with minimum transmission power. We propose an algorithm for nanosensors to estimate the periodic channel by observing signal-to-noise ratio of the beacons transmitted from the data sink. Using real respiration data from multiple subjects, we demonstrate that the proposed algorithm can estimate the minimum... 

    Ion pump based bio-synthetic modulator model for diffusive molecular communications

    , Article 17th IEEE International Workshop on Signal Processing Advances in Wireless Communications, SPAWC 2016, 3 July 2016 through 6 July 2016 ; Volume 2016-August , 2016 ; 9781509017492 (ISBN) Arjmandi, H. R ; Jamali, V ; Ahmadzadeh, A ; Burkovski, A ; Schober, R ; Nasiri Kenari, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    In diffusive molecular communication (DMC), the transmitter has to be able to control the release of signaling molecules for modulation of the information bits. In natural cells, pumping ions is an important control mechanism for releasing molecules which is carried out by ion pumps embedded in the membrane. The activity of the ion pumps is controlled by a driving parameter. In particular, light driven pumps are controlled by light intensity and enable a high degree of spatial and temporal control for modulation functionality. In this paper, a modulator based on ion pumps is proposed for DMC which controls the release rate of the molecules from the transmitter by modulating a light intensity... 

    An online transmission policy for energy harvesting systems with data traffic arrival

    , Article IWCIT 2016 - Iran Workshop on Communication and Information Theory, 3 May 2016 through 4 May 2016 ; 2016 ; 9781509019229 (ISBN) Rezaee, M ; Mirmohseni, M ; Aref, M. R ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    In communications, the nodes with the ability of harvesting energy potentially can prolong the overall network lifetime. In this paper, we consider a single-user energy harvesting wireless communication system, in which arrival data and harvested energy curves are modeled as continuous functions. Our goal is to find an online algorithm for the throughput maximization problem, which only needs the causal information of the arrival processes. We propose a heuristic online algorithm which is efficient for both discrete and continuous models, even when the distributions of harvested energy and arrival data are unknown  

    A thermal-aware shortest hop routing algorithm for in vivo biomedical sensor networks

    , Article ITNG 2009 - 6th International Conference on Information Technology: New Generations, 27 April 2009 through 29 April 2009, Las Vegas, NV ; 2009 , Pages 1612-1613 ; 9780769535968 (ISBN) Tabandeh, M ; Jahed, M ; Ahourai, F ; Moradi, S ; Sharif University of Technology
    Implanted biomedical sensor networks provide a major application of sensor networks in the near future. Their high temperature due to wireless communication, might damage the surrounding tissues. This paper presents an efficient thermal-aware routing. Our proposed protocol states that when some nodes in the shortest path have a high temperature, ignores this path. The simulation results indicate the superiority of the proposed method compared to other thermal-aware routing protocols in terms of reducing temperature without a significant increase in packet delivery delay and power consumption of nodes. © 2009 IEEE  

    Towards the optimal tracking interval management for target tracking wireless sensor networks

    , Article ATC 2009 - Proceedings of the 2009 International Conference on Advanced Technologies for Communications, 12 October 2009 through 14 October 2009 ; 2009 , Pages 161-166 ; 9781424451395 (ISBN) Jamali Rad, H ; Abolhassani, B ; Abdizadeh, M ; Sharif University of Technology
    We consider the minimization of power consumption in target tracking wireless sensor networks (WSNs) using dynamic modification of tracking interval. In this context, we first analyze the performance of such networks, using a quantitative mathematical analysis. Then we calculate an upper bound for the achievable improvement in total power consumption, when using an adaptive time interval modification algorithm for tracking moving objects with acceleration. Towards this optimum functionality, we propose a novel adaptive algorithm (AHC) to adapt the tracking interval such that it minimizes power consumption while keeping an acceptable accuracy. Simulation results show that using the proposed... 

    Symmetric split-row LDPC decoders

    , Article Proceedings - IEEE International Symposium on Circuits and Systems, 28 May 2017 through 31 May 2017 ; 2017 ; 02714310 (ISSN) ; 9781467368520 (ISBN) Shahrad, M ; Shabany, M ; Sharif University of Technology
    LDPC codes are deployed in many modern wired and wireless communication systems. while fully-parallel LDPC decoders are very efficient, they typically suffer from routing complexity. the split-row method effectively reduces this complexity with a minor performance loss. This paper shows the importance of symmetry in Split-Row architectures and proves that the implementation of Split-Row decoders based on new proposed smart column-permuted versions of parity check matrices leads to a better error performance as well as a more efficient hardware. Moreover, in order to achieve optimized column-permuted parity check matrices, a heuristic approach is proposed. This method is then generalized to... 

    Diversity-multiplexing tradeoff in MIMO radars

    , Article IET Radar, Sonar and Navigation ; Volume 11, Issue 4 , 2017 , Pages 691-700 ; 17518784 (ISSN) Nazari Majd, M ; Radmard, M ; Chitgarha, M. M ; Farina, A ; Nayebi, M. M ; Bastani, M. H ; Sharif University of Technology
    Institution of Engineering and Technology  2017
    Two gains play key roles in recently developed multiple-input-multiple-output (MIMO) wireless communication systems: 'spatial diversity' gain and 'spatial multiplexing' gain. The diversity gain (DG) refers to the capability to decrease the error rate of the MIMO channel, whereas the multiplexing gain (MG) implicitly refers to the amount of increase in the capacity of the MIMO channel. It has been shown that there is a fundamental tradeoff between these two types of gains, meaning interplay between increasing reliability (via an increase in the DG) and increasing data rate (via an increase in the MG). On the other hand, recently, MIMO radars have attracted much attention for their superior... 

    Circuit design to improve security of telecommunication devices

    , Article 2017 IEEE 7th Annual Computing and Communication Workshop and Conference, CCWC 2017, 9 January 2017 through 11 January 2017 ; 2017 ; ISBN: 978-150904228-9 Bahrami, H ; Hajsadeghi, K ; Sharif University of Technology
    Security in mobile handsets of telecommunication standards such as GSM, Project 25 and TETRA is very important, especially when governments and military forces use handsets and telecommunication devices. Although telecommunication could be quite secure by using encryption, coding, tunneling and exclusive channel, attackers create new ways to bypass them without the knowledge of the legitimate user. In this paper we introduce a new, simple and economical circuit to warn the user in cases where the message is not encrypted because of manipulation by attackers or accidental damage. This circuit not only consumes very low power but also is created to sustain telecommunication devices in aspect... 

    DC to 40-GHz compact single-layer crossover

    , Article IEEE Microwave and Wireless Components Letters ; Volume 28, Issue 8 , 2018 , Pages 642-644 ; 15311309 (ISSN) Tajik, A ; Fakharzadeh, M ; Mehrany, K ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    In this letter, a compact, wideband, and fully planar microstrip crossover structure is proposed. This design is based on a compact microstrip to coplanar waveguide transition, which has a measured bandwidth extending from dc to 40 GHz. At 20 GHz, the measured insertion loss, return loss, and isolation are better than 0.35, 21, and 19 dB, respectively. This circuit is ultracompact with the core size of 3 mm ×3 mm, which is 0.2λ×0.2 λ at 20 GHz. © 2012 IEEE