فهرست مطالب

Information Systems and Telecommunication - Volume:4 Issue: 1, Jan-Mar 2016

Journal of Information Systems and Telecommunication
Volume:4 Issue: 1, Jan-Mar 2016

  • تاریخ انتشار: 1395/02/07
  • تعداد عناوین: 8
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  • Shahriar Shirvani Moghaddam, Farida Akbari Page 1
    In this paper, a new spatio-temporal based approach is proposed which improves the speed and performance of temporal-based algorithms, conventional Least Mean Square (LMS), Normalized LMS (NLMS) and Variable Step-size LMS (VSLMS), by using the switched beam technique. In the proposed algorithm, first, DOA of the signal source is estimated by MUltiple SIgnal Classification (MUSIC) algorithm. In the second step, depending on the desired user's location, the closest beam of the switched beam system is selected and its predetermined weights are chosen as the initial values for the weight vector. Finally, LMS/NLMS/VSLMS algorithm is applied to initial weights and final weights are calculated. Simulation results show improved convergence and tracking speed and also a higher efficiency in data transmission through increasing the Signal to Interference plus Noise Ratio (SINR) as well as decreasing the Bit Error Rate (BER) and Mean Square Error (MSE), in a joint state. Moreover, Error Vector Magnitude (EVM) as a measure for distortion introduced by the proposed adaptive scheme on the received signal is evaluated for all LMS-based proposed algorithms which are approximately the same as that for conventional ones. In order to investigate the tracking capability of the proposed method, the system is assumed to be time varying and the desired signal location is considered once in the centre of the initial beam and once in the edge of the fixed beam. As depicted in simulation results, the proposed DOAbased methods offer beamforming with higher performance in both cases of the initial beam, centre as the best case and edge as the worst case, with respect to conventional ones. The MSE diagrams for this time varying system show an ideal response for DOA-based methods in the best case. Also, in the worst case, initial height of MSE is reduced and consequently the required iteration to converge is less than the conventional LMS/NLMS/VSLMS.
    Keywords: Beamforming, Switched Beam, LMS, NLMS, DOA, MUSIC.
  • Habib Rasi Page 11
    In this paper, an intelligent algorithm for clustering, intra-pulse modulation detection and separation and identification of overlapping radar pulse train is presented. In most cases, based only on primary features of incoming radar signals, the modern electronic intelligence system cannot recognize the different devices of the same type or class. A very important role is played by Measurement and Signature Intelligence. A radar intercept receiver passively collects incoming pulse samples from a number of unknown emitters. The information such as Pulse Repetition Interval (PRI), Angle of Arrival (AoA), Pulse Width (PW), Radio Frequencies (RF), and Doppler shifts are not usable. In the proposed algorithm, for clustering of overlapping pulses received from self-organization neural network SOFM (due to its high accuracy in comparison with other neural networks, such as CLNN and neural networks (Fuzzy ART), and for detecting intra-pulse modulation type, matrix method, and for identifying the radar type, RBF neural network have been used. The simulation results of the proposed algorithm shows that in the presence 5% noise and 5% missing pulse, the accuracy of the clustering part of the proposed algorithm is equivalent to 91/8%, intra-pulse modulation recognition accuracy is 98%, the detection accuracy is 2/99%, and the total output of the algorithm precision is 89/244%, respectively.
    Keywords: Pulse Train, Matrix Multiplication Method, Radar Identification, Neural Networks
  • Hojjatollah Hamidi Page 19
    The transformation technique relies on the comparison of parity values computed in two ways. The fault detection structures are developed and they not only detected subsystem faults but also corrected faults introduced in the data processing system. Concurrent parity values techniques are very useful in detecting numerical error in the data processing operations, where a single fault can propagate to many output faults. Parity values are the most effective tools used to detect faults occurring in the code stream. In this paper, we present a methodology for redundant systems that allows to detect faults. Checkpointing is the typical technique to tolerate such faults. This paper presents a checkpointing approach to operate on encoded data. The advantage of this method is that it is able to achieve very low overhead according to the specific characteristic of an application. The numerical results of the multiple checkpointing technique confirm that the technique is more efficient and reliable by not only distributing the process of checkpointing over groups of processors. This technique has been shown to improve both the reliability of the computation and the performance of the checkpointing.
    Keywords: Transformation Techniques, Information Systems, Redundancy, Checkpointing
  • Peyman Goli, Mohammad Reza Karami, Mollaei Page 27
    A new speech intelligibility improvement method for near-end listening enhancement in noisy environments is proposed. This method improves speech intelligibility by optimizing energy correlation of one-third octave bands of clean speech and enhanced noisy speech without power increasing. The energy correlation is determined as a cost function based on frequency band gains of the clean speech. Interior-point algorithm which is an iterative procedure for the nonlinear optimization is used to determine the optimal points of the cost function because of nonlinearity and complexity of the energy correlation function. Two objective intelligibility measures, speech intelligibility index and short-time objective intelligibility measure, are employed to evaluate the noisy enhanced speech intelligibility. Furthermore, the speech intelligibility scores are compared with unprocessed speech and a baseline method under various noisy conditions. The results show large intelligibility improvements with the proposed method over the unprocessed noisy speech.
    Keywords: Near, end Speech Enhancement, Intelligibility Improvement, Energy Correlation, Optimization Algorithms
  • Mohammad Reza Ahadiat, Paeiz Azmi, Afrooz Haghbin Page 34
    This paper addresses the performance of MIMO-OFDM communication system in environments where the interfering noise exhibits non-Gaussian behavior due to impulsive phenomena. It presents the design and simulation of an iterative technique that aims to minimize the effect of impulsive noise on the performance of the MIMO-OFDM communication system under Additive White Gaussian Noise (AWGN) channel. This is a new method to recover the signals corrupted by impulsive noise in MIMO-OFDM systems over In-home Power Line Channel. The location and amplitude Impulsive noise at the receiver using an adaptive threshold to be determined. Reduced Impulsive noise effects using the mask based on the soft decision method. By iteration, the original signal estimation can be used to improve the impulsive noise estimation. This continuous loop impulsive noise detection and mitigation a better estimate of the original signal is obtained. The Bit Error Rate (BER) performance of the MIMO-OFDM system in an impulsive noise environment was evaluated. The results show the superiority and robustness of the proposed method.
    Keywords: Power Line Communication, MIMO, OFDM, Impulsive Noise, Iterative Method
  • Roya Hassanian, Esfahani, Mohammad, Javad Kargar Page 42
    Web traffic analysis is a well-known e-marketing activity. Today most of the news agencies have entered the web providing a variety of online services to their customers. The number of online news consumers is also increasing dramatically all over the world. A news website usually benefits from different acquisition channels including organic search services, paid search services, referral links, direct hits, links from online social media, and e-mails. This article presents the results of an empirical study of analyzing referral traffic of a news website through data mining techniques. Main methods include correlation analysis, outlier detection, clustering, and model performance evaluation. The results decline any significant relationship between the amount of referral traffic coming from a referrer website and the website's popularity state. Furthermore, the referrer websites of the study fit into three clusters applying K-means Squared Euclidean Distance clustering algorithm. Performance evaluations assure the significance of the model. Also, among detected clusters, the most populated one has labeled as "Automatic News Aggregator Websites" by the experts. The findings of the study help to have a better understanding of the different referring behaviors, which form around 15% of the overall traffic of Iranian Student's News Agency (ISNA) website. They are also helpful to develop more efficient online marketing plans, business alliances, and corporate strategies.
    Keywords: Referral Traffic, Data Mining, K, means Clustering, Online News
  • Zainab Baharvand, Ahmad Hakimi Page 50
    In this paper, an ultra-broad bandwidth, low noise, and high gain-flatness CMOS distributed amplifier (CMOS-DA) based on a novel gain-cell is presented. The new gain-cell that enhances the output impedance as a result the gain substantially over conventional RGC is the improved version of Regulated Cascode Configuration (RGC). The new gaincell based CMOS-DA is analyzed and simulated in the standard 0.13 μm-CMOS technology. The simulated results of the proposed CMOS-DA are included 14.2 dB average power gain with less than ± 0.5 dB fluctuations over the 3-dB bandwidth of 23 GHz while the simulated input and output return losses (S11 and S22) are less than -10 dB. The IIP3 and input referred 1-dB compression point are simulated at 15 GHz and achieved dBm and -6.34 dBm, respectively. The average noise figure (NF) in the entire interest band has a low value of 3.65 dB, and the DC power dissipation is only 45.63 mW. The CMOS-DA is powered by 0.9 V supply voltage. Additionally, the effect of parameters variation on performance specifications of the proposed design is simulated by Monte Carlo simulations to ensure that the desired accuracy is yielded.
    Keywords: Ultra, broad Band, CMOS Distributed Amplifier, Modified Regulated Cascode Configuration (MRGC), Low Noise
  • Zeynab Mottaghinia, Ali Ghaffari Page 59
    The Delay Tolerant Mobile Sensor Networks (DTMSNs) distinguish themselves from conventional sensor networks by means of some features such as loose connectivity, node mobility, and delay tolerability. It needs to be acknowledged that traditional end-to-end routing protocols cannot be applied usefully in such challenging network conditions because of intermittent connections and/or long delays. Hence, this research is intended to propose a Unicast Tree-based Data Gathering protocol (UTDG) to resolve this problem. A UTDG includes 3 phases: tree formation phase, data collection and data transmission phase, and finally the updating phase. The proposed protocol constructs a tree in each community on the basis of transmission ranking, contact probability and the link expiration time. The selection of the next-hop node is based on the tree structure rather than forwarding the message to the neighbor node directly. Each node unicasts the data to its parent in the related community, and the root of the tree successively sends the data to the sink node. The authors contend, based on the simulation results of the study, that the proposed protocol can gain significantly higher message delivery rates with lower transmission overhead and also lower delay in data delivery than the other existing DTMSNs routing protocols in some applications.
    Keywords: Delay, Tolerant Mobile Sensor Networks (DTMSNs), Unicast Tree, based Data Gathering protocol (UTDG), Transmission Ranking, Contact Probability, Link Expiration Time