List of Articles Bandwidth

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  1 - EBG Structures Properties and their Application to Improve Radiation of a Low Profile Antenna
  Masoumeh Rezaei Abkenar Pejman Rezaei
  10.7508/jist.2013.04.006
  In this paper we have studied the characteristics of mushroom-like Electromagnetic Band Gap (EBG) structure and performance of a low profile antenna over it. Afterward, a novel EBG surface is presented by some modifications in mushroom-like EBG structure. This structure More

  In this paper we have studied the characteristics of mushroom-like Electromagnetic Band Gap (EBG) structure and performance of a low profile antenna over it. Afterward, a novel EBG surface is presented by some modifications in mushroom-like EBG structure. This structure, which has more compact electrical dimensions, is analyzed and its electromagnetic properties are derived. Results show that resonant frequency of this novel structure is about 15.3% lower than the basic structure with the same size. Moreover, the novel EBG structure has been used as the ground plane of antenna. Its application has improved radiation of a low profile dipole antenna. The antenna performance over the new EBG ground plane is compared with the conventional mushroom-like EBG structure. Simulation results show that using this slot loaded EBG surface, results in 13.68dB improvement in antenna return loss, in comparison with conventional mushroom-like EBG, and 33.87dB improvement in comparison with metal ground plane. Besides, results show that, EBG ground planes have increased the input match frequency bandwidth of antenna. Manuscript profile
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  2 - Statistical Analysis of Different Traffic Types Effect on QoS of Wireless Ad Hoc Networks
  Mahmood Mollaei Gharehajlu Saadan Zokaei Yousef Darmani
  10.7508/jist.2015.01.002
  IEEE 802.11 based wireless ad hoc networks are highly appealing owing to their needless of infrastructures, ease and quick deployment and high availability. Vast variety of applications such as voice and video transmission over these types of networks need different net More

  IEEE 802.11 based wireless ad hoc networks are highly appealing owing to their needless of infrastructures, ease and quick deployment and high availability. Vast variety of applications such as voice and video transmission over these types of networks need different network performances. In order to support quality of service for these applications, characterizing both packets arrival and available resources are essential. To address these issues we use Effective Bandwidth/Effective Capacity theory which expresses packet arrival and service model statistically. Effective Bandwidth asymptotically represents arrival traffic specifications using a single function. Also, Effective Capacity statistically describes service model of each node. Based on this theory, at first we modeled each node’s service as an ON/OFF process. Then a new closed form of Effective Capacity is proposed which is a simple function and is dependent on a few parameters of the network. Afterward the performance of different traffic patterns such as constant bit rate, Poisson and Markov Modulated Poisson process are statistically evaluated in the case of both single and aggregate traffic modes. Using the proposed model we will show that traffic pattern affects QoS parameters even if all models have the same average packet arrival rate. We prove the accuracy of our model by a series of simulations which are run using NS2 simulator. Manuscript profile
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  3 - Analysis of Imperfect Space Channel for the Next Generation Satellite Networks
  pedram hajipour ali shahzadi
  10.7508/jist.2017.20.004
  An efficient space data management is imperative in guaranteeing the best performance with a fair distribution of next generation satellite networks. Therefore, one of the major challenges of implementing this kind of future satellite networks is evaluation any untruste More

  An efficient space data management is imperative in guaranteeing the best performance with a fair distribution of next generation satellite networks. Therefore, one of the major challenges of implementing this kind of future satellite networks is evaluation any untrusted error for the best Quality of Service (QoS). Therefore, Bit Error Rate (BER) criteria based on the type of space channel which it can be defined prefect or imperfect state between satellites and ground stations seems to be a major challenge for space communication. In this paper, the authors provide a bandwidth sharing algorithm for a proposed future satellite networks under multi-beam prototype. This structure has many antennas in transmitter and receiver sides (satellite and ground stations) which they will be communication together based on space data. Using the above framework, the coverage probability and MIMO capacity for a typical multi-beam satellite system is compared with a single antenna for satellite and multi-antenna for area side coverage based on input parameters such as path loss and Signal to Noise Ratio (SNR), respectively. Finally, the bit error rate based on imperfect channel estimation is obtained by employing 4-QAM and QPSK digital modulations and the number of antennas followed by a comparative analysis. Manuscript profile
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  4 - Clasification of custumers of internet services, using data mining algorithms
  farid norozi hamed kazemipoor
  10.7508/jstpi.2017.01.002
  Nowadays, the role of customers has shifted from followers of the producers to guiding them.That is why the classification of customers in targeting and customizing services and prioritization of companies products on the basis of profitability makes great help. Interne More

  Nowadays, the role of customers has shifted from followers of the producers to guiding them.That is why the classification of customers in targeting and customizing services and prioritization of companies products on the basis of profitability makes great help. Internet service providers in the market, are competing with a lot of competitors because investing in on communications and internet services are profitable.In order to progress in the market, it is necessary to offer new services and innovation.To get broader share of the market, the internet providers has got to have sufficient knowledge of the market and customers, retain existing customers and attract new customers.By classifying and clustering its customers, and while identifying and supporting its active and beneficial customers, such companies can remove their offbeat customers from services providing cycle.Using data mining algorithm, this research detecting and identifying of such customers, make the internet service provider closer to their goals. Manuscript profile
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  5 - Design and Simulation of a Two Stages OPAMP Using Positive Feedback for Achieving to a High Unity Gain Bandwidth and a High DC Gain
  P. Moallem A. Shiri Sichani
  The Fabrication of switch capacitor Filters and continuous time CMOS circuits, with a suitable unity gain bandwidth, a high DC gain and a high quality factor are a major challenge in integrated circuits design basically. This article is proposed a novel positive feedbac More

  The Fabrication of switch capacitor Filters and continuous time CMOS circuits, with a suitable unity gain bandwidth, a high DC gain and a high quality factor are a major challenge in integrated circuits design basically. This article is proposed a novel positive feedback topology for designing of OPAMP kernel and then a sample of OPAMP based on this method by tuning of the fabrication parameters is designed. The results of simulations which are done in frequency and time domain demonstrate that unity gain bandwidth of the designed OPAMP is greater than 1.4GHz and DC gain is greater than 108dB that in comparison with similar designs based on positive feedback can demonstrate there are plentiful increment in unity gain bandwidth and suitable increment in DC gain. The phase margin of the designed OPAMP is greater than 170 degree. Moreover, investigation of the proposed design outputs in time domain demonstrates the stability of the proposed OPAMP. Manuscript profile
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  6 - Joint Bandwidth Extension and Vector Taylor Series Approaches to Enhance the Corrupted Narrowband Speech
  S. Pourmohammadi M. Vali M. Ghadyani
  In this paper, we introduce an efficient and previously unreported approach to enhance the quality of corrupted narrowband speech signal using joint Vector Taylor Series (VTS) and Bandwidth Extension (BWE) algorithms. First, feature vectors extracted from the noisy narr More

  In this paper, we introduce an efficient and previously unreported approach to enhance the quality of corrupted narrowband speech signal using joint Vector Taylor Series (VTS) and Bandwidth Extension (BWE) algorithms. First, feature vectors extracted from the noisy narrowband signal have modified applying VTS technique. Then, the estimation of corresponding wideband features have derived from the compensated parameters using two different artificial BWE methods (Envelope prediction with GMM and Neural Network). Finally, the distance between the wideband feature vectors and their estimated values evaluated using Log Spectral Distortion (LSD) measurement criteria. The results of implementation clearly show the advantage of proposed idea to improve the quality of the contaminated speech. In addition, we show that artificial BWE of speech signal, based on the neural network envelope extension outperforms better results in comparison with the GMM algorithm. Manuscript profile