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Symmetry/Asymmetry in Wireless Communication and Sensor Networks

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A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Computer".

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 19178

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Dr. Haitao Xu

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Guest Editor

Department of Communication Engineering, University of Science and Technology Beijing, Beijing 100083, China
Interests: wireless resource allocation and management; wireless communications and networking; dynamic game and mean field game theory; big data analysis and security
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

During the past decade, human beings have stepped into the era of information explosion, and the popularization of traffic-intensive applications of all types of communication terminals has led to an unprecedented increase in the demand for information and communication. Both wired and wireless communications play a fundamental role in the information age. With the rapid increase in the wireless communication demand, the development of wireless communication systems has encountered bottlenecks. The continuous advancement of 5G commercialization and the development and application of the Internet of Things, Internet of Vehicles, wireless body area networks, and wireless sensor networks have put forward new requirements for wireless networks. In addition to the larger bandwidth and lower delay, wireless networks are also required to have a certain degree of intelligence, more efficient resource allocation algorithms, more reasonable network access methods, and more secure information safeguard measures.

Symmetry is an extraordinary characteristic which has widely been deployed in the research fields of wireless communication. This Special Issue invites original research that investigates the symmetry/asymmetry characteristics in wireless communication. We hope to spread knowledge among researchers, designers, manufacturers, and users in this exciting field with this issue.

Potential topics include, but are not limited to, the following:

Symmetry/asymmetry protocol design in wireless communication and sensor networks;
Symmetry/asymmetry communication frameworks in wireless communication and sensor networks;
Symmetry/asymmetry transmission in satellite communication;
Symmetry/asymmetry data communication in wireless sensor networks/Internet of Things/Internet of Vehicles;
Symmetry/asymmetry privacy and security challenges in wireless communication and sensor networks;
Symmetry/asymmetry resource allocation schemes in wireless communication and sensor networks;
Symmetry/asymmetry in intelligent wireless communication and intelligent Internet of Things/Internet of Vehicles.

Dr. Haitao Xu
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (11 papers)

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Research

18 pages, 12620 KiB

Open AccessArticle

Miniaturized Coplanar Waveguide-Fed UWB Antenna for Wireless Applications

by Maryam S. Jameel, Yaqeen S. Mezaal and Dogu Cagdas Atilla

Symmetry 2023, 15(3), 633; https://0-doi-org.brum.beds.ac.uk/10.3390/sym15030633 - 02 Mar 2023

Cited by 11 | Viewed by 2770

Abstract

This study presents a compact ultra-wideband (UWB) antenna fed by a coplanar waveguide (CPW) with huge bandwidth for the demands of modern wireless communities. To overcome some technical limitations of the employed substrate and UWB antenna design, a slotted patch resonator was used to create and simulate this antenna based on Locked-Key topology. It has been printed on a 1.5 mm-thick FR4 substrate with a dielectric constant of 4.4. A feeder with characteristic impedances of 50 Ω has been employed. A CST electromagnetic simulator has been employed to simulate and analyze the antenna design. It is operated within the UWB spectrum with a bandwidth of 10.354 GHz, spanning 3.581 to 14 GHz. The overall surface area is 27 × 25 mm². The gain and maximum efficiency within UWB are better than 3 dBi and 82%, respectively. The antenna is fabricated, and the simulated results are correlated with the measured ones. Finally, the equivalent circuit models for the antenna and rectifier circuit are simulated and measured. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Wireless Communication and Sensor Networks)

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19 pages, 3057 KiB

Open AccessArticle

Genetic Algorithm for Optimizing Energy Efficiency in Downlink mmWave NOMA System with Imperfect CSI

by Reem Aldebes, Kaharudin Dimyati and Effariza Hanafi

Symmetry 2022, 14(11), 2345; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14112345 - 08 Nov 2022

Viewed by 1194

Abstract

Nonorthogonal multiple access (NOMA) is considered a promising technique for improving energy efficiency (EE) in beyond-5G wireless systems. In this paper, we investigate the maximization of EE of downlink wireless systems by combining mmWave with NOMA technologies, considering the asymmetric required data rate of user applications. We propose a genetic algorithm (GA) to solve the non-convex energy efficiency problem for an imperfect CSI downlink mmWave NOMA system. The studied mixed-integer optimization problem was converted to an integer optimization problem and solved using a GA, which determines the best clustering members in mmWave NOMA. The required population size of the proposed GA was determined to evaluate its effectiveness for a massive number of users. In addition, the GA’s convergence to the optimal solution for light traffic and relatively heavy traffic was also analyzed. Our results illustrate that the solution obtained solution via GA is almost equal to the optimal value and outperforms the conventional orthogonal multiple access, where the EE is improved by more than 75%. Finally, the impact of the estimation error of CSI on the system performance was evaluated at different required SINR scenarios. The results show that EE is degraded in the case of imperfect CSI case but is still close to the optimal solution. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Wireless Communication and Sensor Networks)

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14 pages, 5747 KiB

Open AccessArticle

Design of a Filtering Power Divider with Simple Symmetric Structure Using Stubs

by Saeed Roshani, Salah I. Yahya, Jamal Rastad, Yaqeen Sabah Mezaal, Louis W. Y. Liu and Sobhan Roshani

Symmetry 2022, 14(10), 1973; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14101973 - 21 Sep 2022

Cited by 5 | Viewed by 1698

Abstract

A power divider (PD) with a wide stopband and simple symmetric structure using open- and short-ended stubs is analyzed and implemented in this paper. In the proposed power divider, for the first time, the output resistor is divided into two sections and open- and short-ended stubs are used between the resistors. The incorporated open- and short-ended stubs have resulted in a controllable bandwidth for the proposed PD, which resulted in 40% of the fractional bandwidth considering 3 dB attenuation of insertion loss. The proposed PD operates at 2 GHz, which shows more than 20 dB attenuation for the return and isolation losses. In addition, the obtained insertion loss at the operating frequency is approximately 0.3 dB, which shows a minor loss, and also, high isolation is achieved in the device. Moreover, 20 dB and 30 dB attenuation levels have been achieved for second and third harmonics. The results show high performance for the proposed power divider. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Wireless Communication and Sensor Networks)

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15 pages, 3204 KiB

Open AccessArticle

Beamforming Optimization for Intelligent Reflecting Surface-Assisted MIMO Systems

by Wenjuan Zhang, Honggui Deng, Youzhen Li, Zaoxing Zhu, Chengzuo Peng and Gang Liu

Symmetry 2022, 14(8), 1510; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14081510 - 23 Jul 2022

Cited by 2 | Viewed by 1500

Abstract

To improve the spectral efficiency of symmetry-based intelligent reconfigurable surface (IRS)-assisted MIMO communication systems, this paper investigates the joint precoding and passive beamforming optimization problem for millimeter-wave point-to-point MIMO systems under both ideal and practical IRS phase shifts. For the ideal IRS phase shifts setup, we derive a simplified approximate spectral efficiency expression based on Jensen’s inequality and propose a minimum mean square error (MMSE)-based algorithm to transform the simplified non-convex problem into a solvable convex function. For the practical IRS phase shifts setup, we propose a multi-start stepwise optimization algorithm to obtain the passive beamforming by stepwise iterative search. Finally, with the above-obtained passive beamforming, the optimal precoding is derived by performing the singular value decomposition (SVD) on the effective channel and water-filling power allocation. The simulation results verify our performance analysis and demonstrate that spectral efficiency can be effectively improved compared to various benchmark schemes. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Wireless Communication and Sensor Networks)

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18 pages, 2212 KiB

Open AccessArticle

A Joint Positioning Algorithm in Industrial IoT Environments with mm-Wave Communications

by Hua-Min Chen, Siyu Huang, Peng Wang, Tao Chen, Chao Fang, Shaofu Lin and Fan Li

Symmetry 2022, 14(7), 1335; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14071335 - 28 Jun 2022

Cited by 1 | Viewed by 1540

Abstract

With the real restriction of packet size and transmission power, a joint UL-AoA (Uplink Angle of Arrival) and UL-TDOA (Uplink Time Difference of Arrival) positioning method is discussed for the Industrial Internet of Things (IIoT), which demands high accuracy of position information. One motivation of the UL positioning method of IIoT is an asymmetric network and uplink traffic is dominant in most identified scenarios. Further, IIoT sensors are power limited for low cost, compared to the transmission power of base stations and other normal user equipment. This paper considers an environment of a 5G-enabled IIoT network with massive Multiple input multiple output (MIMO) antennas, beamforming and millimeter operating bands. After reviewing downlink positioning reference signal (PRS) and uplink sounding reference signal for positioning (SRS-Pos), a general system model and a theoretical localization problem is derived under the joint positioning method. The provided simulation results help to investigate the impact of system configurations on positioning measurements. Further, through the test in this paper, it is proved that joint positioning outperforms that of the time only or angle only method. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Wireless Communication and Sensor Networks)

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14 pages, 2137 KiB

Open AccessArticle

SQRT: A Secure Querying Scheme of Routing Table Based on Oblivious Transfer

by Yue Zhao, Bo Tian, Ning Hu, Qi Zhao, Yiru Niu, Leyu Lin and Yarang Yang

Symmetry 2022, 14(6), 1245; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14061245 - 15 Jun 2022

Cited by 1 | Viewed by 1314

Abstract

The user equipment and directory server stay in the state of asymmetric information in anonymous networks, so that it is hard to coordinate information leakage prevention and information sharing when we explore the routing addressing technology. The severe security risk faced by existing anonymous networks, such as Tor and I2P, is the leakage of privacy information of routing nodes. This paper tries to resolve this problem and proposes a novel secure querying scheme of the routing table (SQRT) based on oblivious transfer, which can effectively ensure that both user equipment and directory server faithfully follow the routing querying protocol and protect the privacy information of both parties to the greatest extent. The SQRT scheme can realize that the directory server cannot only send the required routing nodes to the user equipment, but can also ensure that the directory server cannot know the exact routing nodes received by the user equipment and protect the information of other routing nodes in the directory server from disclosure. Security analysis shows that in the scenario where the directory server and user equipment are semi-honest, respectively, the SQRT scheme can ensure the privacy of both directory server and user equipment. The experimental simulation results show that compared with existing schemes, the SQRT scheme has obvious performance advantages in terms of the degree of anonymity, protocol running time, and communication traffic. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Wireless Communication and Sensor Networks)

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16 pages, 1561 KiB

Open AccessArticle

Energy Efficiency Optimization of Massive MIMO System with Uplink Multi-Cell Based on Imperfect CSI with Power Control

by Jie Zhang, Honggui Deng, Youzhen Li, Zaoxing Zhu, Gang Liu and Hongmei Liu

Symmetry 2022, 14(4), 780; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14040780 - 08 Apr 2022

Cited by 9 | Viewed by 1755

Abstract

In order to solve the energy efficiency optimization problem in the uplink multi-cell massive MIMO system, this paper constructs the system transmission model, of which the channel is symmetry, based on user and base station, and deduces the expression of data transmission rate of each user. Then, we establish a model of the spectral and energy efficiency of multi-cell massive MIMO system by analyzing the pilot transmission and channel estimation. We also derive the nonconvex function for the energy efficiency optimization, which is difficult to solve directly. Therefore, we propose an improved particle swarm optimization algorithm to obtain the suboptimal solution, under low complexity, by optimizing the distribution of user power. To demonstrate the advantages of our proposed algorithm, we simulate the energy efficiency performance of the algorithm. The results show that the proposed algorithm can effectively improve the energy efficiency of the system. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Wireless Communication and Sensor Networks)

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18 pages, 1860 KiB

Open AccessArticle

Hybrid Precoding-Based Millimeter Wave Massive MIMO-NOMA Systems

by Zaoxing Zhu, Honggui Deng, Fuxin Xu, Wenjuan Zhang, Gang Liu and Yinhao Zhang

Symmetry 2022, 14(2), 412; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14020412 - 19 Feb 2022

Cited by 6 | Viewed by 1648

Abstract

A symmetry-based hybrid precoder and combiner is a high spectral efficiency structure in millimeter-wave (mmWave) massive multiple-input multiple-output (mMIMO) non-orthogonal multiple access (NOMA) system. To improve the spectral efficiency of the mmWave mMIMO-NOMA system, we first propose a user grouping scheme to suppress the strong inter-user interference caused by NOMA, then the hybrid precoder based on user channel alignment and the zero-forcing algorithm is constructed to further improve the signal-to-interference-plus-noise ratio (SINR) of the receiver. Subsequently, the non-convex spectral efficiency optimization problem is transformed into a convex optimization problem of inter-cluster power allocation and the closed-form solution for the optimal power under the minimum rate constraint is obtained by solving the KKT condition to further improve the spectral efficiency. The simulation results show that the proposed scheme can achieve higher spectral efficiency compared to orthogonal multiple access (OMA), fixed power allocation (FPA), K-means, and cluster head selection (CHS). Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Wireless Communication and Sensor Networks)

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16 pages, 542 KiB

Open AccessArticle

Eigenvalue-Based Spectrum Sensing with Small Samples Using Circulant Matrix

by Liping Du, Yuting Fu, Yueyun Chen, Xiaojian Wang and Xiaoyan Zhang

Symmetry 2021, 13(12), 2330; https://0-doi-org.brum.beds.ac.uk/10.3390/sym13122330 - 05 Dec 2021

Cited by 3 | Viewed by 1371

Abstract

In cognitive radio (CR) networks, eigenvalue-based detectors (EBDs) have attracted much attention due to their good performance of detecting secondary users (SUs). In order to further improve the detection performance of EBDs with short samples, we propose two new detectors: average circulant matrix-based Roy’s largest root test (ACM-RLRT) and average circulant matrix-based generalized likelihood ratio test (ACM-GLRT). In the proposed method, the circulant matrix of samples at each time instant from SUs is calculated, and then, the covariance matrix of the circulant matrix is averaged over a short period of time. The eigenvalues of the achieved average circulant matrix (ACM) are used to build our proposed detectors. Using a circulant matrix can improve the dominant eigenvalue of covariance matrix of signals and also the detection performance of EBDs even with short samples. The probability distribution functions of the detectors undernull hypothesis are analyzed, and the asymptotic expressions for the false-alarm and thresholds of two proposed detectors are derived, respectively. The simulation results verify the effectiveness of the proposed detectors. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Wireless Communication and Sensor Networks)

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19 pages, 3749 KiB

Open AccessArticle

5G Network Data Migration Service Based on Edge Computing

by Furong Li and Duan Wang

Symmetry 2021, 13(11), 2134; https://0-doi-org.brum.beds.ac.uk/10.3390/sym13112134 - 09 Nov 2021

Cited by 5 | Viewed by 1477

Abstract

With the development of mobile network technology, the continuous increase of mobile traffic has put forward higher requirements for quality of service (QoS) issues such as asymmetric transmission delay. The paper mainly studies the energy distribution problem on the migration data link from the terminal device to the edge node in the mobile edge network. Multiple data service packages are set up at each hop on the migration data link, and these data service packages compete with each other, and ultimately only one terminal provides and stores energy for this hop. The migration strategy of the data service package is affected by the edge node, and the edge node changes the migration strategy according to the migration strategy of the data service package. The paper is based on the formation of nodes between the data service packages of different nodes on the 5G network data link to jointly control the migration strategy, coordinate the migration strategy formulated, and better coordinate the migration strategy. In this competitive game model, the optimal migration strategy of nodes is found out according to the terminal equipment access requirements. Then according to the node stability rules, the composition of nodes when the nodes are stable is obtained, the migration strategy of stable nodes and the migration and spectrum strategies of operators are obtained, and the migration strategy of joint control provides energy for edge nodes. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Wireless Communication and Sensor Networks)

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10 pages, 2766 KiB

Open AccessArticle

Predator–Prey Model Based Asymmetry Resource Allocation in Satellite–Terrestrial Network

by Zhipeng Li, Meng Li and Qian Wang

Symmetry 2021, 13(11), 2113; https://0-doi-org.brum.beds.ac.uk/10.3390/sym13112113 - 07 Nov 2021

Cited by 3 | Viewed by 1379

Abstract

In the traditional satellite networks, network resources are mainly allocated among all the satellites based on the same allocation algorithm. This kind of symmetry model limits the increase of throughput. In this paper, we study an asymmetry resource allocation method in a satellite–terrestrial network and propose a Lotka–Volterra based predator–prey model to achieve optimal resource allocation among different satellites. In the proposed satellite–terrestrial network, we divide all the satellites into two groups, and we try to achieve load stability between these two satellites groups. Using the predator–prey model, one group is the prey–satellites, which can obtain service requirements from mobile users. The other group is considered as predator–satellites, which can only obtain the loads from the group of the prey–satellites. Once the satellites are divided into two groups using the Lotka–Volterra model, the resource allocation problem among these satellites in two groups would be asymmetry resource. We prove the existence of solutions to the proposed model. Numerical simulation results are given to show the correctness and effectiveness of the proposed model. Full article

(This article belongs to the Special Issue Symmetry/Asymmetry in Wireless Communication and Sensor Networks)

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