Research

Jump to: Review

15 pages, 1793 KiB

Open AccessArticle

Node Selection Algorithm for Network Coding in the Mobile Wireless Network

by Dexia Jiang and Leilei Li

Symmetry 2021, 13(5), 842; https://doi.org/10.3390/sym13050842 - 10 May 2021

Cited by 1 | Viewed by 1822

In the multicast network, network coding has proven to be an effective technique to approach maximum flow capacity. Although network coding has the advantage of improving performance, encoding nodes increases the cost and delay in wireless networks. Therefore, minimizing encoding nodes is of [...] Read more.

In the multicast network, network coding has proven to be an effective technique to approach maximum flow capacity. Although network coding has the advantage of improving performance, encoding nodes increases the cost and delay in wireless networks. Therefore, minimizing encoding nodes is of great significance to improve the actual network’s performance under a maximum multicast flow. This paper seeks to achieve partial improvements in the existing selection algorithm of encoding nodes in wireless networks. Firstly, the article gives the condition for an intermediate node to be an encoding node. Secondly, a maximum flow algorithm, which depends on the depth-first search method, is proposed to optimize the search time by selecting the larger augmentation flow in each step. Finally, we construct a random graph model to simulate the wireless network and the maximum multicast flow algorithm to analyze the statistical characteristics of encoding nodes. This paper aims at the optimization to find the minimal number of required coding nodes which means the minimum energy consumption. Meanwhile, the simulations indicate that the curve of coding nodes tends to be a geometric distribution, and that the curve of the maximum flow tends to be symmetric as the network scale and the node covering radius increase. Full article

(This article belongs to the Special Issue Symmetry and Asymmetry in Communications Engineering)

► Show Figures

Graphical abstract

28 pages, 4077 KiB

Open AccessArticle

Multi-Objective Caching Optimization for Wireless Backhauled Fog Radio Access Network

by Alaa Bani-Bakr, MHD Nour Hindia, Kaharudin Dimyati, Effariza Hanafi and Tengku Faiz Tengku Mohmed Noor Izam

Symmetry 2021, 13(4), 708; https://doi.org/10.3390/sym13040708 - 17 Apr 2021

Cited by 10 | Viewed by 1645

Abstract

Proactive content caching in a fog radio access network (F-RAN) is an efficient technique used to alleviate delivery delay and traffic congestion. However, the symmetric caching of the content is impractical due to the dissimilarity among the contents popularity. Therefore, in this paper, [...] Read more.

Proactive content caching in a fog radio access network (F-RAN) is an efficient technique used to alleviate delivery delay and traffic congestion. However, the symmetric caching of the content is impractical due to the dissimilarity among the contents popularity. Therefore, in this paper, a multi-objective random caching scheme to balance the successful transmission probability (STP) and delay in wireless backhauled F-RAN is proposed. First, stochastic geometry tools are utilized to derive expressions of the association probability, STP, and average delivery delay. Next, the complexity is reduced by considering the asymptotic STP and delay in the high signal-to-noise ratio (SNR) regime. Then, aiming at maximizing the STP or minimizing the delay, the multi-objective cache placement optimization problem is formulated. A novel projected multi-objective cuckoo search algorithm (PMOCSA) is proposed to obtain the Pareto front of the optimal cache placement. The numerical results show that PMOCSA outperforms the original multi-objective cuckoo search algorithm (MOCSA) in terms of convergence to a feasible Pareto front and its rate. It also shows that the proposed multi-objective caching scheme significantly outperforms the well-known benchmark caching schemes by up to

40 %

higher STP and

85 %

lower average delay. Full article

(This article belongs to the Special Issue Symmetry and Asymmetry in Communications Engineering)

► Show Figures

Figure 1

11 pages, 2117 KiB

Open AccessArticle

MEOD: Memory-Efficient Outlier Detection on Streaming Data

by Ankita Karale, Milena Lazarova, Pavlina Koleva and Vladimir Poulkov

Symmetry 2021, 13(3), 458; https://doi.org/10.3390/sym13030458 - 12 Mar 2021

Cited by 4 | Viewed by 1695

Abstract

In this paper, a memory-efficient outlier detection (MEOD) approach for streaming data is proposed. The approach uses a local correlation integral (LOCI) algorithm for outlier detection, finding the outlier based on the density of neighboring points defined by a given radius. The radius [...] Read more.

In this paper, a memory-efficient outlier detection (MEOD) approach for streaming data is proposed. The approach uses a local correlation integral (LOCI) algorithm for outlier detection, finding the outlier based on the density of neighboring points defined by a given radius. The radius value detection problem is converted into an optimization problem. The radius value is determined using a particle swarm optimization (PSO)-based approach. The results of the MEOD technique application are compared with existing approaches in terms of memory, time, and accuracy, such as the memory-efficient incremental local outlier factor (MiLOF) detection technique. The MEOD technique finds outlier points similar to MiLOF with nearly equal accuracy but requires less memory for processing. Full article

(This article belongs to the Special Issue Symmetry and Asymmetry in Communications Engineering)

► Show Figures

Figure 1

11 pages, 2966 KiB

Open AccessArticle

Wireless Sensor Network (WSN) Configuration Method to Increase Node Energy Efficiency through Clustering and Location Information

by Jinsoo Kim, Donghwan Lee, Jaejoon Hwang, Sunghoon Hong, Dongil Shin and Dongkyoo Shin

Symmetry 2021, 13(3), 390; https://doi.org/10.3390/sym13030390 - 27 Feb 2021

Cited by 19 | Viewed by 2063

Abstract

Wireless Sensor Network (WSN) technology, for services that are difficult to access or which need to be continuously monitored regardless of location, needs further research and development due to an expansion of fields where it can be applied and due to increases in [...] Read more.

Wireless Sensor Network (WSN) technology, for services that are difficult to access or which need to be continuously monitored regardless of location, needs further research and development due to an expansion of fields where it can be applied and due to increases in efficiency. In particular, in the field of defense, research on the latest IT technologies including sensor networks is being actively conducted as an alternative to the risky use of personnel in areas such as surveillance and surveillance reconnaissance. This paper experimented with analyzing the conditions necessary for increasing the energy efficiency of the nodes constituting a sensor network using a clustering routing technique and a location-based routing technique. The derived factors include a method for selecting a cluster head (CH), a method for establishing a path from each channel to a base station (BS), and a method for transmitting collected data. We experimented with the derived factors and proposed a WSN configuration method that increases the energy efficiency of each node by applying optimal results and methods that were verified experimentally. Full article

(This article belongs to the Special Issue Symmetry and Asymmetry in Communications Engineering)

► Show Figures

Figure 1

23 pages, 663 KiB

Open AccessArticle

A Primer on Design Aspects and Recent Advances in Shuffle Exchange Multistage Interconnection Networks

by Oluwatosin Ahmed Amodu, Mohamed Othman, Nur Arzilawati Md Yunus and Zurina Mohd Hanapi

Symmetry 2021, 13(3), 378; https://doi.org/10.3390/sym13030378 - 26 Feb 2021

Cited by 10 | Viewed by 2216

Abstract

Interconnection networks provide an effective means by which components of a system such as processors and memory modules communicate to provide reliable connectivity. This facilitates the realization of a highly efficient network design suitable for computational-intensive applications. Particularly, the use of multistage interconnection [...] Read more.

Interconnection networks provide an effective means by which components of a system such as processors and memory modules communicate to provide reliable connectivity. This facilitates the realization of a highly efficient network design suitable for computational-intensive applications. Particularly, the use of multistage interconnection networks has unique advantages as the addition of extra stages helps to improve the network performance. However, this comes with challenges and trade-offs, which motivates researchers to explore various design options and architectural models to improve on its performance. A particular class of these networks is shuffle exchange network (SEN) which involves a symmetric N-input and N-output architecture built in stages of

N / 2

switching elements each. This paper presents recent advances in multistage interconnection networks with emphasis on SENs while discussing pertinent issues related to its design aspects, and taking lessons from the past and current literature. To achieve this objective, applications, motivating factors, architectures, shuffle exchange networks, and some of the performance evaluation techniques as well as their merits and demerits are discussed. Then, to capture the latest research trends in this area not covered in contemporary literature, this paper reviews very recent advancements in shuffle exchange multistage interconnection networks within the last few years and provides design guidelines as well as recommendations for future consideration. Full article

(This article belongs to the Special Issue Symmetry and Asymmetry in Communications Engineering)

► Show Figures

Figure 1

15 pages, 8091 KiB

Open AccessArticle

Electromagnetic Safety of Remote Communication Devices—Videoconference

by Artur Przybysz, Krystian Grzesiak and Ireneusz Kubiak

Symmetry 2021, 13(2), 323; https://doi.org/10.3390/sym13020323 - 16 Feb 2021

Cited by 6 | Viewed by 4084

Abstract

Devices powered by electricity become sources of electromagnetic emissions in the course of their operation. In the case of devices oriented to process information, these emissions can have a character of revealing emissions, i.e., those whose reception and analysis allow for remote reconstruction [...] Read more.

Devices powered by electricity become sources of electromagnetic emissions in the course of their operation. In the case of devices oriented to process information, these emissions can have a character of revealing emissions, i.e., those whose reception and analysis allow for remote reconstruction of related data. The best known example of this phenomenon is the formation of revealing emissions during the operation of imaging devices: monitors, projectors or printers. Increasingly more often, these components are used for communication in the form of videoconferences with other network users. The article presents the result of tests and analyses of threats related to the use of such solutions (monitors, personal computers, VoIP terminals) for the confidentiality of conversations and the data presented during them. The focus is on video signals; however, the potential possibilities of revealing speech signals were also indicated. Such phenomenon causes a huge threat to data confidentiality because the combination of graphics and sound can undoubtedly contain much more information about the protected data than just graphics or sound separately. The presented results of analyses apply to graphic data, possibilities of non-invasive acquisition of such data, similarity of images and of patterns and reconstructed image and image recognition. The results indicate that there is still a risk of loss of data confidentiality due to a phenomenon of an electromagnetic leakage, and specialized instrumentation is not required for its interception under favorable circumstances. This may particularly apply to audio data that may be accidentally received by home radio receivers. In particular, the presented results of analyses apply to a Special Issue of Symmetry which is characterized by security and privacy in communication systems and networks, signal processing, video and image processing, multimedia communications and electromagnetic compatibility. All these scientific and technical areas have either symmetrical or asymmetrical approaches, and they have to be taken into consideration as a whole in order to choose the best combinations to protect processed information. Full article

(This article belongs to the Special Issue Symmetry and Asymmetry in Communications Engineering)

► Show Figures

Figure 1

14 pages, 1141 KiB

Open AccessArticle

Evaluating the Coding Performance of 360° Image Projection Formats Using Objective Quality Metrics

by Ikram Hussain, Oh-Jin Kwon and Seungcheol Choi

Symmetry 2021, 13(1), 80; https://doi.org/10.3390/sym13010080 - 05 Jan 2021

Cited by 3 | Viewed by 2536

Abstract

Recently, 360° content has emerged as a new method for offering real-life interaction. Ultra-high resolution 360° content is mapped to the two-dimensional plane to adjust to the input of existing generic coding standards for transmission. Many formats have been proposed, and tremendous work [...] Read more.

Recently, 360° content has emerged as a new method for offering real-life interaction. Ultra-high resolution 360° content is mapped to the two-dimensional plane to adjust to the input of existing generic coding standards for transmission. Many formats have been proposed, and tremendous work is being done to investigate 360° videos in the Joint Video Exploration Team using projection-based coding. However, the standardization activities for quality assessment of 360° images are limited. In this study, we evaluate the coding performance of various projection formats, including recently-proposed formats adapting to the input of JPEG and JPEG 2000 content. We present an overview of the nine state-of-the-art formats considered in the evaluation. We also propose an evaluation framework for reducing the bias toward the native equi-rectangular (ERP) format. We consider the downsampled ERP image as the ground truth image. Firstly, format conversions are applied to the ERP image. Secondly, each converted image is subjected to the JPEG and JPEG 2000 image coding standards, then decoded and converted back to the downsampled ERP to find the coding gain of each format. The quality metrics designed for 360° content and conventional 2D metrics have been used for both end-to-end distortion measurement and codec level, in two subsampling modes, i.e., YUV (4:2:0 and 4:4:4). Our evaluation results prove that the hybrid equi-angular format and equatorial cylindrical format achieve better coding performance among the compared formats. Our work presents evidence to find the coding gain of these formats over ERP, which is useful for identifying the best image format for a future standard. Full article

(This article belongs to the Special Issue Symmetry and Asymmetry in Communications Engineering)

► Show Figures

Figure 1

22 pages, 691 KiB

Open AccessArticle

DSM: Delayed Signature Matching in Deep Packet Inspection

by Yingpei Zeng, Shanqing Guo, Ting Wu and Qiuhua Zheng

Symmetry 2020, 12(12), 2011; https://doi.org/10.3390/sym12122011 - 05 Dec 2020

Viewed by 2172

Abstract

Deep Packet Inspection (DPI) is widely used in network management and network security systems. The core part of existing DPI is signature matching, and many researchers focus on improving the signature-matching algorithms. In this paper, we work from a different angle: The scheduling [...] Read more.

Deep Packet Inspection (DPI) is widely used in network management and network security systems. The core part of existing DPI is signature matching, and many researchers focus on improving the signature-matching algorithms. In this paper, we work from a different angle: The scheduling of signature matching. We propose a Delayed Signature Matching (DSM) method, in which we do not always immediately match received packets to the signatures since there may be not enough packets received yet. Instead, we predefine some rules, and evaluate the packets against these rules first to decide when to start signature matching and which signatures to match. The predefined rules are convenient to create and maintain since they support custom expressions and statements and can be created in a text rule file. The correctness and performance of the DSM method are theoretically analyzed as well. Finally, we implement a prototype of the DSM method in the open-source DPI library nDPI, and find that it can reduce the signature-matching time about 30∼84% in different datasets, with even smaller memory consumption. Note that the abstract syntax trees (ASTs) used to implement DSM rule evaluation are usually symmetric, and the DSM method supports asymmetric (i.e., single-direction) traffic as well. Full article

(This article belongs to the Special Issue Symmetry and Asymmetry in Communications Engineering)

► Show Figures

Figure 1

21 pages, 3765 KiB

Open AccessArticle

Fine-Grained Mechanical Chinese Named Entity Recognition Based on ALBERT-AttBiLSTM-CRF and Transfer Learning

by Liguo Yao, Haisong Huang, Kuan-Wei Wang, Shih-Huan Chen and Qiaoqiao Xiong

Symmetry 2020, 12(12), 1986; https://doi.org/10.3390/sym12121986 - 30 Nov 2020

Cited by 20 | Viewed by 3270

Abstract

Manufacturing text often exists as unlabeled data; the entity is fine-grained and the extraction is difficult. The above problems mean that the manufacturing industry knowledge utilization rate is low. This paper proposes a novel Chinese fine-grained NER (named entity recognition) method based on [...] Read more.

Manufacturing text often exists as unlabeled data; the entity is fine-grained and the extraction is difficult. The above problems mean that the manufacturing industry knowledge utilization rate is low. This paper proposes a novel Chinese fine-grained NER (named entity recognition) method based on symmetry lightweight deep multinetwork collaboration (ALBERT-AttBiLSTM-CRF) and model transfer considering active learning (MTAL) to research fine-grained named entity recognition of a few labeled Chinese textual data types. The method is divided into two stages. In the first stage, the ALBERT-AttBiLSTM-CRF was applied for verification in the CLUENER2020 dataset (Public dataset) to get a pretrained model; the experiments show that the model obtains an F1 score of 0.8962, which is better than the best baseline algorithm, an improvement of 9.2%. In the second stage, the pretrained model was transferred into the Manufacturing-NER dataset (our dataset), and we used the active learning strategy to optimize the model effect. The final F1 result of Manufacturing-NER was 0.8931 after the model transfer (it was higher than 0.8576 before the model transfer); so, this method represents an improvement of 3.55%. Our method effectively transfers the existing knowledge from public source data to scientific target data, solving the problem of named entity recognition with scarce labeled domain data, and proves its effectiveness. Full article

(This article belongs to the Special Issue Symmetry and Asymmetry in Communications Engineering)

► Show Figures

Figure 1

20 pages, 4511 KiB

Open AccessArticle

Performance Evaluation of Keyword Extraction Methods and Visualization for Student Online Comments

by Feng Liu, Xiaodi Huang, Weidong Huang and Sophia Xiaoxia Duan

Symmetry 2020, 12(11), 1923; https://doi.org/10.3390/sym12111923 - 22 Nov 2020

Cited by 8 | Viewed by 4731

Abstract

Topic keyword extraction (as a typical task in information retrieval) refers to extracting the core keywords from document topics. In an online environment, students often post comments in subject forums. The automatic and accurate extraction of keywords from these comments are beneficial to [...] Read more.

Topic keyword extraction (as a typical task in information retrieval) refers to extracting the core keywords from document topics. In an online environment, students often post comments in subject forums. The automatic and accurate extraction of keywords from these comments are beneficial to lecturers (particular when it comes to repeatedly delivered subjects). In this paper, we compare the performance of traditional machine learning algorithms and two deep learning methods in extracting topic keywords from student comments posted in subject forums. For this purpose, we collected student comment data from a period of two years, manually tagging part of the raw data for our experiments. Based on this dataset, we comprehensively compared the five typical algorithms of naïve Bayes, logistic regression, support vector machine, convolutional neural networks, and Long Short-Term Memory with Attention (Att-LSTM). The performances were measured by the four evaluation metrics. We further examined the keywords by visualization. From the results of our experiment and visualization, we conclude that the Att-LSTM method is the best approach for topic keyword extraction from student comments. Further, the results from the algorithms and visualization are symmetry, to some degree. In particular, the extracted topics from the comments posted at the same stages of different teaching sessions are, almost, reflection symmetry. Full article

(This article belongs to the Special Issue Symmetry and Asymmetry in Communications Engineering)

► Show Figures

Figure 1

19 pages, 8743 KiB

Open AccessArticle

Method of Colors and Secure Fonts Used for Source Shaping of Valuable Emissions from Projector in Electromagnetic Eavesdropping Process

by Alexandru Boitan, Ireneusz Kubiak, Simona Halunga, Artur Przybysz and Andrzej Stańczak

Symmetry 2020, 12(11), 1908; https://doi.org/10.3390/sym12111908 - 20 Nov 2020

Cited by 8 | Viewed by 4109

Abstract

The protection of information processed electronically involves a large number of IT devices from computer sets or laptops to monitors, printers, servers, etc. In many cases, classified information processing might be associated with the use of projectors, which are an indispensable element of [...] Read more.

The protection of information processed electronically involves a large number of IT devices from computer sets or laptops to monitors, printers, servers, etc. In many cases, classified information processing might be associated with the use of projectors, which are an indispensable element of meetings for a limited group of people. Such devices are connected to computers through interfaces of various analogue and digital standards and can become an additional source of unwanted emissions, and the distinctive features of these emissions allow the information displayed to be unwantedly reproduced. This paper offers evidence of the existing threat related to electromagnetic infiltration of several projectors, by showing images reconstructed from registered revealing emissions. The paper presents an analysis of several solutions that can be used to reduce the level of infiltration susceptibility of projectors or to highlight this property in the device assessment process. The possibilities of using special computer fonts and the so-called method of colors—background color and text color—is analyzed. The tests were carried out on randomly selected projectors in two independent laboratories, and, based on these results, a number of interesting conclusions have been highlighted at the end. Full article

(This article belongs to the Special Issue Symmetry and Asymmetry in Communications Engineering)

► Show Figures

Graphical abstract

13 pages, 945 KiB

Open AccessArticle

Dynamic Job Scheduling Strategy Using Jobs Characteristics in Cloud Computing

by Mohammed A. Alsaih, Rohaya Latip, Azizol Abdullah, Shamala K. Subramaniam and Kamal Ali Alezabi

Symmetry 2020, 12(10), 1638; https://doi.org/10.3390/sym12101638 - 06 Oct 2020

Cited by 8 | Viewed by 2345

Abstract

A crucial performance concern in distributed decentralized environments, like clouds, is how to guarantee that jobs complete their execution within the estimated completion times using the available resources’ bandwidth fairly and efficiently while considering the resource performance variations. Formerly, several models including reservation, [...] Read more.

A crucial performance concern in distributed decentralized environments, like clouds, is how to guarantee that jobs complete their execution within the estimated completion times using the available resources’ bandwidth fairly and efficiently while considering the resource performance variations. Formerly, several models including reservation, migration, and replication heuristics have been implemented to solve this concern under a variety of scheduling techniques; however, they have some undetermined obstacles. This paper proposes a dynamic job scheduling model (DTSCA) that uses job characteristics to map them to resources with minimum execution time taking into account utilizing the available resources bandwidth fairly to satisfy the cloud users quality of service (QoS) requirements and utilize the providers’ resources efficiently. The scheduling algorithm makes use of job characteristics (length, expected execution time, expected bandwidth) with regards to available symmetrical and non-symmetrical resources characteristics (CPU, memory, and available bandwidth). This scheduling strategy is based on generating an expectation value for each job that is proportional to how these job’s characteristics are related to all other jobs in total. That should make their virtual machine choice closer to their expectation, thus fairer. It also builds a feedback method which deals with reallocation of failed jobs that do not meet the mapping criteria. Full article

(This article belongs to the Special Issue Symmetry and Asymmetry in Communications Engineering)

► Show Figures

Graphical abstract

Review

Jump to: Research

22 pages, 251 KiB

Open AccessReview

Device-To-Device Communication in 5G Environment: Issues, Solutions, and Challenges

by Mohd Hirzi Adnan and Zuriati Ahmad Zukarnain

Symmetry 2020, 12(11), 1762; https://doi.org/10.3390/sym12111762 - 24 Oct 2020

Cited by 43 | Viewed by 6228

Abstract

Device-to-device (D2D) communication produces a new dimension in the mobile environment, easing the data exchange process between physically neighboring devices. To achieve an effective utilization of available resources, reduce latency, improve data rates, and increase system capacity, D2D communication utilizes nearby communicating devices. [...] Read more.

Device-to-device (D2D) communication produces a new dimension in the mobile environment, easing the data exchange process between physically neighboring devices. To achieve an effective utilization of available resources, reduce latency, improve data rates, and increase system capacity, D2D communication utilizes nearby communicating devices. The mobile operator’s action to collect the short-range communications for maintenance of the proximity-based services and improve the performance of networks drives the development of D2D. This paper presents an extensive review of proposed solutions aiming to enhance the security in D2D communication. The main goal of the research is to present an extensive review of the recent advances in various D2D domains such as the discovery process, mode selection schemes, interference management, power control techniques and finally the mode selection for D2D applications for 5G technologies. Additionally, we highlight the open problems and identify the challenges with regard to the D2D communication problem. Full article

(This article belongs to the Special Issue Symmetry and Asymmetry in Communications Engineering)

Journal Menu

Journal Browser

Symmetry and Asymmetry in Communications Engineering

Share This Special Issue

Special Issue Editors

Special Issue Information

Published Papers (13 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI