Search for: error-performance
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    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... 

    TTCN: A new approach for low-power split-row LDPC decoders

    , Article Proceedings - IEEE International Symposium on Circuits and Systems, 24 May 2015 through 27 May 2015 ; Volume 2015-July , 2015 , Pages 2001-2004 ; 02714310 (ISSN) ; 9781479983919 (ISBN) Shahrad, M ; Shabany, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Split-Row technique is proved to be one of the most effective methods to reduce the routing complexity of fully-parallel LDPC decoders. This technique is based on the idea of splitting each check node processor to multiple smaller processors. This paper introduces a new method, to increase the power-efficiency of Split-Row LDPC decoders. The proposed method is called trust to the truthful check node (TTCN), enabling the decoder to only depend on a portion of check node processors at specific decoding iterations. This leads to an average reduction of 30%-40% in the check node dynamic power consumption. This is achieved by means of trust to a minority of check node processors and gating the... 

    Asymptotic analysis of error probability and outage behavior of equal-gain combining

    , Article IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, 13 September 2009 through 16 September 2009, Tokyo ; 2009 ; 9781424451234 (ISBN) Safavi, S. E ; Khalaj, B. H ; Saheban, F ; Sharif University of Technology
    In this paper, we investigate the error probability, diversity analysis and outage capacity of a general multiple-antenna equal-gain receive combining (EGC) scheme with an arbitrary number of antennas at high signal-to-noise (SNR) ratio. As will be shown, the proposed approach which is based on Taylor expansion provides a powerful tool for analysis of EGC schemes in terms of diversity and outage capacity. The approximations used in this approach lead to low complexity solutions that are very close to exact values, as shown by the simulation results. ©2009 IEEE  

    Rate-maximizing adaptation in multiantenna OFDM systems with space-time-frequency coding

    , Article 2006 IEEE International Conference on Communications, ICC 2006, Istanbul, 11 July 2006 through 15 July 2006 ; Volume 6 , 2006 , Pages 2905-2910 ; 05361486 (ISSN); 1424403553 (ISBN); 9781424403554 (ISBN) Roozbahani, M. G ; Khalaj, B. H ; Sharif University of Technology
    In this paper, we first propose a space-time-frequency (STF) coding method for multiple-input multiple-output orthogonal frequency division multiplexing (MIMOOFDM) transmission over frequency-selective fading channels and then, based on channel mean feedback model, we develop an adaptive MIMO-OFDM transmitter by applying an adaptive energy and bit loading scheme across OFDM subcarriers. Under the constraints of fixed transmit-energy and prescribed error performance, our objective is to maximize the transmission rate. Simulation results are presented which confirm the performance of our proposed system and show that under certain circumstances, the transmission rate improves considerably as... 

    Error performance analysis for generalized orthogonal frequency division multiplexing

    , Article Computers and Electrical Engineering ; Volume 61 , 2017 , Pages 139-150 ; 00457906 (ISSN) Abbaszadeh, M. H ; Khalaj, B. H ; Haghbin, A ; Sharif University of Technology
    Generalized Frequency Division Multiplexing (GFDM) is a cyclic filtered multicarrier modulation that may be employed for many new wireless applications. However, due to its non-orthogonal structure, a trade-off between the complexity and error performance should be considered in the design of GFDM receivers. This study proposes an orthogonal cyclic filtered multicarrier modulation called Generalized Orthogonal Frequency Division Multiplexing (GOFDM), which is based on the cyclic Perfect Reconstruction-Quadrature Mirror Filter (PR-QMF) bank. We first derive the frequency domain matrix descriptions for GOFDM linear receivers based on which, the impact of PR-QMF bank on the GOFDM error... 

    Efficient secure channel coding scheme based on low-density Lattice codes

    , Article IET Communications ; Volume 10, Issue 11 , 2016 , Pages 1365-1373 ; 17518628 (ISSN) Hooshmand, R ; Aref, M. R ; Sharif University of Technology
    Institution of Engineering and Technology  2016
    In this study, the authors introduce an efficient secure channel coding (joint cryptography-channel coding) scheme based on Latin square low-density lattice codes (Latin square LDLCs) over unconstrained power additive white Gaussian noise channel. They benefit the properties of Latin square LDLCs to dramatically reduce the key size of the proposed scheme while having an acceptable level of security compared with previous similar schemes. To reduce the key size, they consider two approaches: (i) saving the generating sequence of parity-check matrix of used Latin square LDLC as the part of secret key set; (ii) employing the Hermite normal form of the generator matrix of used Latin square LDLC... 

    Set of uniquely decodable codes for overloaded synchronous CDMA

    , Article IET Communications ; Volume 10, Issue 10 , 2016 , Pages 1236-1245 ; 17518628 (ISSN) Singh, A ; Amini, A ; Singh, P ; Marvasti, F ; Sharif University of Technology
    Institution of Engineering and Technology 
    In this study, the authors consider the designing of a new set of uniquely decodable codes for uncoded synchronous overloaded code division multiple access for the number of codes exceeding the assigned code length. For the construction, the proposed recursive method at iteration-k generates a matrix that can be classified into k orthogonal subsets of different dimensions. Out of them, all besides the largest (binary Hadamard) one are ternary in nature. There resides an inbuilt twin tree structured cross-correlation hierarchy that facilitates an advantageous balance between the auto and intergroup cross-correlation for the signatures in a subset. This opportunity is further leveraged by the... 

    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... 

    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... 

    Error behavior modeling in Capacitance-Resistance Model: A promotion to fast, reliable proxy for reservoir performance prediction

    , Article Journal of Natural Gas Science and Engineering ; Volume 77 , May , 2020 Mamghaderi, A ; Aminshahidy, B ; Bazargan, H ; Sharif University of Technology
    Elsevier B. V  2020
    Using the original form of Capacitance-Resistance Model (CRM), as a waterflooding performance prediction tool, for modeling real reservoirs makes some unavoidable errors. Combination of this model with available data assimilation methods yields more powerful simulation tool with updating parameters over time. However, the inherent uncertainty arisen by modeling complex reservoirs with only a limited number of CRM parameters is not addressed yet. In this study, the model error behavior has been simulated through a physically-based dynamical system in which it has been correlated with the original model parameters. The ensemble-based Kalman filter (EnKF) data assimilation method has been... 

    Secure one-way relaying scheme based on random difference family (RDF) lattice codes

    , Article Wireless Networks ; Volume 27, Issue 7 , 2021 , Pages 4615-4634 ; 10220038 (ISSN) Bagheri, Kh ; Khodaiemehr, H ; Eghlidos, T ; Panario, D ; Sharif University of Technology
    Springer  2021
    In this paper, we present a one-way relaying scheme in which two wireless nodes create an information flow to each other via a single decode-and-forward (DF) relay. We consider an additional secrecy constraint for protection against an honest-but-curious relay. Indeed, while the relay should decode the source message, it should be fully ignorant about the message content. We provide a secure lattice coding strategy based on random difference families (RDF) lattice codes for unidirectional Gaussian relay channels. RDF lattice codes are carved from infinite RDF lattices using a shaping algorithm. By RDF lattice we mean a Construction A lattice with a QC-LDPC code, which is obtained from random... 

    Optimal HDA codes for sending a Gaussian source over a Gaussian channel with bandwidth compression in the presence of an interference

    , Article 2011 IEEE Information Theory Workshop, ITW 2011 ; 2011 , Pages 325-329 ; 9781457704376 (ISBN) Varasteh, M ; Behroozi, H ; Sharif University of Technology
    In this paper, we consider transmission of a Gaussian source over a Gaussian channel under bandwidth compression in the presence of interference known only to the transmitter. We study hybrid digital-analog (HDA) joint source-channel coding schemes and propose two novel coding schemes that achieve the optimal mean-squared error (MSE) distortion. This can be viewed as the extension of results by Wilson et al. [1], originally proposed for sending a Gaussian source over a Gaussian channel in two cases: 1) Matched bandwidth with known interference only at the transmitter, 2) bandwidth compression where there is no interference in the channel. The proposed HDA codes can cancel the interference of... 

    Twin tree hierarchy: a regularized approach to construction of signature matrices for overloaded CDMA

    , Article Wireless Communications and Mobile Computing ; Volume 16, Issue 17 , 2016 , Pages 3070-3088 ; 15308669 (ISSN) Singh, A ; Singh, P ; Amini, A ; Marvasti, F ; Sharif University of Technology
    John Wiley and Sons Ltd  2016
    Overloaded code division multiple access being the only means of the capacity extension for conventional code division multiple access accommodates more number of signatures than the spreading gain. Recently, ternary Signature Matrices with Orthogonal Subsets (SMOS) has been proposed, where the capacity maximization is 200%. The proposed multi-user detector using matched filter exploits the twin tree hierarchy of correlation among the subsets to guarantee the errorless recovery. In this paper, we feature the non-ternary version of SMOS (i.e., 2k-ary SMOS) of same capacity, where the binary alphabets in all the k constituent (orthogonal) subsets are unique. Unlike ternary, the tree hierarchy... 

    Efficient secure channel coding based on quasi-cyclic low-density parity-check codes

    , Article IET Communications ; Volume 3, Issue 2 , 2009 , Pages 279-292 ; 17518628 (ISSN) Sobhi Afshar, A. A ; Eghlidos, T ; Aref, M. R ; Sharif University of Technology
    A secure channel coding (joint encryption-channel coding) scheme provides both data security and reliability in one combined process to achieve faster processing and/or more efficient implementation. The issue of using quasi-cyclic low-density parity-check (QC-LDPC) codes in a symmetric-key secure channel coding scheme is addressed. A set of this class of LDPC codes has recently been recommended by the NASA Goddard Space Flight Center for near-earth and deep-space communications. The proposed scheme provides an efficient error performance, an acceptable level of security and a low-complexity practicable implementation. The results indicate that the proposed scheme can efficiently employ...