No. 3 (2019)
Published:
2019-09-30
ARTICLES FROM THIS ISSUE
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Comparison of Multicast Algorithm Evaluation Results in Low and High Multicast Saturation Environments
Abstract
The multicast quality of service-enabled routing is a computationally challenging task. Despite ongoing research efforts, the associated mathematical problems are still considered to be NP-hard. In certain applications, computational complexity of finding the optimal connection between a set of network devices may be a particularly difficult challenge. For example, connecting a small group of participants of a teleconference is not much more complex than setting up a set of mutual point-to-point connections. On the other hand, satisfying the demand for such services as IPTV, with their receivers constituting the majority of the network, requires applying appropriate optimization methods in order to ensure real system execution. In this paper, algorithms solving this class of problems are considered. The notion of multicast saturation is introduced to measure the amount of multicast participants relative to the entire network, and the efficiency of the analyzed algorithms is evaluated for different saturation degrees.
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Spline-Extrapolation Method in Traffic Forecasting in 5G Networks
Abstract
This paper considers the problem of predicting self-similar traffic with a significant number of pulsations and the property of long-term dependence, using various spline functions. The research work focused on the process of modeling self-similar traffic handled in a mobile network. A splineextrapolation method based on various spline functions (linear, cubic and cubic B-splines) is proposed to predict selfsimilar traffic outside the period of time in which packet data transmission occurs. Extrapolation of traffic for short- and long-term forecasts is considered. Comparison of the results of the prediction of self-similar traffic using various spline functions has shown that the accuracy of the forecast can be improved through the use of cubic B-splines. The results allow to conclude that it is advisable to use spline extrapolation in predicting self-similar traffic, thereby recommending this method for use in practice in solving traffic prediction-related problems.
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Multifactor Authentication and Key Management Protocol for WSN-assisted IoT Communication
Abstract
In this paper a novel multi-factor authentication protocol for IoT applications, relying on enhanced Rabinassisted elliptic curve cryptography, biometric features and time stamping methods, is developed. Furthermore, a fuzzy verification algorithm has been developed to perform receiverlevel user verification, making computation efficient in terms of computational overhead as well as latency. An NS2 simulation-based performance assessment has revealed that the multifactor authentication and key management models we have proposed are capable of not only avoiding security breaches, such as smart card loss (SCLA) and impersonation attacks, but can also ensure the provision of maximum possible QoS levels by offering higher packet delivery and minimum latency rates.
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A Novel Graph-modification Technique for User Privacy-preserving on Social Networks
Abstract
The growing popularity of social networks and the increasing need for publishing related data mean that protection of privacy becomes an important and challenging problem in social networks. This paper describes the (k,l k,l k,l)-anonymity model used for social network graph anonymization. The method is based on edge addition and is utility-aware, i.e. it is designed to generate a graph that is similar to the original one. Different strategies are evaluated to this end and the results are compared based on common utility metrics. The outputs confirm that the na¨ıve idea of adding some random or even minimum number of possible edges does not always produce useful anonymized social network graphs, thus creating some interesting alternatives for graph anonymization techniques.
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An Inclusive Performance Analysis of Single-branch Single-relay AF Transmission in a Mixed Rayleigh-Nakagami-m Fading Environment
Abstract
In this paper, the end-to-end performance of a single-branch two-hop amplify-and-forward (AF) relaying network in a mixed Rayleigh-Nakagami-m fading environment, is investigated. Four different fading scenarios and three standard relay configurations for each scenario are considered. Exact analytical expressions for the outage probability and tight upper bounds for the ergodic capacity are derived. Results of Monte Carlo simulations are provided to verify the accuracy of the analytical results.
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New OSTBC for Blind Channel Estimation and Tracking in MIMO-OFDM Systems
Abstract
Applying orthogonal space time block coding (OSTBC) to multiple-input multiple-output (MIMO) systems helps reduce receiver complexity. However, this approach has been applied only to flat fading channels, as when the channel is a frequency selective fading MIMO channel, OSTBC cannot be used directly since its orthogonal propriety may be lost. Furthermore, the MIMO channel is not always known. To deal with this problem, many techniques were proposed to estimate the channel using a training sequence. Unfortunately, these techniques reduce the useful spectral bandwidth. This paper proposes OSTBC for blind channel estimation and data detection in the case of a MIMO frequency selective channel. The aim of this new OSTBC is twofold: to solve the ambiguity of channel estimation and to reduce the complexity of the detector. By exploiting the well-known technique of orthogonal frequency division multiplexing (OFDM), the frequency selective fading MIMO channel is split into a set of flat fading subchannels. Moreover, to accommodate the fact that a MIMO channel can be time varying, the steady state Kalman channel estimator (SS-KCE) is extended to track the channel’s fast variations. The performance of the proposed blind algorithm is related by the adequate choice of the number of subcarriers and it is compared with other existing approaches by means of Monte Carlo simulations.
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Complex Signal Mapping for Improving Spectral Efficiency of Li-Fi Systems
Abstract
Light fidelity (Li-Fi) systems based on the orthogonal frequency division multiplexing (OFDM) scheme have gained more attention in the communications circles, as a means to provide high spectral efficiency and ensure stricter data rate requirements for visible light communication (VLC) systems. However, common OFDM schemes employ Hermitian symmetry to obtain a real-valued signal which is necessary in intensity modulation and direct detection (IM/DD) optical systems, at the expense of doubling the required bandwidth. In this paper, a novel transmission scheme for an OFDM-based Li-Fi system is proposed to tackle the issue in question. A new approach to complex signal mapping (CSM), based on the pairing function method, has been developed for Li-Fi systems. It does not require Hermitian symmetry and, hence, saves about 50% of the required bandwidth. Unlike existing OFDM-based VLC approaches, the proposed scheme employs CSM to ensure a real and positive signal without Hermitian symmetry in order to fully utilize the bandwidth available to Li-Fi networks. Simulation results show that the proposed scheme significantly outperforms other systems in terms of spectral efficiency. The CSM-OFDM based Li-Fi system also achieves a good peak-to-average power ratio (PAPR) reduction with acceptable bit-error-rate (BER) performance, compared to conventional approaches.
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A Modified Approach to Punctured Product Polar Codes
Abstract
A high-performance polar code introduced as a product polar code can be constructed by concatenating two short length polar codes. The punctured structure of this code was achieved by puncturing one of its constituent codes. The constructed polar code provided better performance than a single polar code in the error floor region. However, its performance in the waterfall region was not as good as that of single polar codes. This paper proposes a new puncturing algorithm for product codes constructed by two identical polar codes. Puncturing is conducted on both constituent codes, to ensure that the new code outperforms the previously punctured product polar and single polar codes. This is evident in both waterfall and error floor regions.
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Ku Band Bethe Hole Coupler Using Gap Waveguide Technology
Abstract
The gap waveguide technology is a new technique used for designing and fabricating microwave components, ensuring a low-loss and easy fabrication process, especially at high frequencies, and allowing for the production of multilayer structures due to the lack of requirement of an electrical connection between the metal layers of the waveguide structure. This paper presents the design and areas of implementation of single-hole and multi-hole 20 dB Bethe couplers, using the groove gap waveguide (GGW) technology for Ku band. Simulation results show that the operating bandwidth of the proposed design is over 40% wider, and its isolation rate is more than 25 dB higher. By using the multi hole configuration, a bandwidth that is more than 59% wider and the isolation rate of over 30 dB may be obtained.
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A Survey on Data Perception in Cognitive Internet of Things
Abstract
A Cognitive Internet of Things (CIoT) is a brand of Internet of Things (IoT) with cognitive and agreeable mechanisms, which are incorporated to advance performance and accomplish insights into real world environments. CIoT can perceive present system’s conditions, analyze the apparent information, make smart choices, and increase the network performance. In this survey paper, we present classifications of data perception techniques used in CIoT. This paper also compares the data perception works against energy consumption, network life-time, resource allocation, and throughput, as well as quality of data and delay. In addition, simulation tools for IoT and their performance are discussed. Finally, we provide the model of cognitive agent-based data perception in CIoT for future research and development, which ensures the network performance in terms of reliability, energy efficient, accuracy, scalable, fault tolerant, and quality of data.
