Symmetry

Research

18 pages, 513 KiB

Open AccessArticle

Performance Analysis of ARIS-NOMA Systems under Cascade Rician Channels

by Xuliang Liu, Xinwei Yue, Zhiping Lu and Tianwei Hou

Symmetry 2024, 16(3), 321; https://doi.org/10.3390/sym16030321 - 7 Mar 2024

Viewed by 1020

Active reconfigurable intelligent surface (ARIS) has sparked more attention due to its capability to overcome the impact of double fading. This paper introduces using an ARIS to aid non-orthogonal multiple access (NOMA) communications over cascade Rician fading channels, where the direct links between [...] Read more.

Active reconfigurable intelligent surface (ARIS) has sparked more attention due to its capability to overcome the impact of double fading. This paper introduces using an ARIS to aid non-orthogonal multiple access (NOMA) communications over cascade Rician fading channels, where the direct links between the base station and users are seriously blocked. By applying ARIS, it can amplify the superposed signals to overcome the double pass loss effect caused by passive RIS. Both ARIS and NOMA can have synergistic impacts on sixth-generation communication systems. New approximated and asymptotic expressions in terms of outage probability and ergodic data rate of the k-th user are deduced for ARIS-NOMA systems. Based on asymptotic analytical results, we further calculate the diversity order and high signal-to-noise ratio slope of the k-th user. Finally, the system throughput of ARIS-NOMA is discussed in the delay-constrained transmission mode. Monte Carlo numerical results are performed to verify that: (1) the outage behaviors of ARIS-NOMA are better than that of ARIS-assisted orthogonal multiple access (OMA); (2) as the impact of thermal noise caused by ARIS becomes larger, the communication performance from the base station to ARIS, then to users, becomes worse; (3) the ARIS-NOMA systems have the ability to provide the improved ergodic data rate relative to ARIS-OMA. Full article

(This article belongs to the Special Issue New Advances in New-Generation Communication and Symmetry)

► Show Figures

Figure 1

17 pages, 804 KiB

Open AccessArticle

Performance Analysis and Simulation of IRS-Aided Wireless Networks Communication

by Osman Dikmen

Symmetry 2024, 16(2), 254; https://doi.org/10.3390/sym16020254 - 19 Feb 2024

Viewed by 1671

Abstract

This paper introduces the novel IRS-based Optimal Relay Selection (ORS-IRS) method, aimed at analyzing the performance of wireless communication systems with an emphasis on symmetry. The ORS-IRS approach presents an innovative communication algorithm that seamlessly integrates Intelligent Reflecting Surfaces (IRS) with relay selection [...] Read more.

This paper introduces the novel IRS-based Optimal Relay Selection (ORS-IRS) method, aimed at analyzing the performance of wireless communication systems with an emphasis on symmetry. The ORS-IRS approach presents an innovative communication algorithm that seamlessly integrates Intelligent Reflecting Surfaces (IRS) with relay selection techniques. Through adaptive adjustments of reflection coefficients, IRS elements efficiently manipulate incoming signals, fostering symmetry in signal strength enhancement and latency reduction for improved signal delivery to the intended destination. This symmetrical optimization in channel capacity and transmission power ensures reliable data transmission with low latency, achieved through the seamless integration of IRS and relay selection techniques. In contrast, the Cell-Free Massive MIMO (CF-M-MIMO), with its decentralized architecture, excels in serving a larger user base and attaining remarkable capacity gains, showcasing a different dimension of symmetry. The Decode-and-Forward (DF) relaying approach demonstrates its potential in enhancing signal reliability across extended distances, contributing to the overall symmetry of the comparative analysis. This comprehensive evaluation provides valuable insights into selecting appropriate transmission strategies, particularly for applications that demand high capacity and reliability in the design of modern wireless communication systems with a symmetrical focus. Full article

(This article belongs to the Special Issue New Advances in New-Generation Communication and Symmetry)

► Show Figures

Figure 1

16 pages, 1135 KiB

Open AccessArticle

Provably Secure Data Access Control Protocol for Cloud Computing

by Ji Zhang, Anmin Chen and Ping Zhang

Symmetry 2023, 15(12), 2111; https://doi.org/10.3390/sym15122111 - 24 Nov 2023

Viewed by 1192

Abstract

Currently, cloud storage servers are controlled by a third-party administrator. This semi-trusted approach gives rise to security concerns. Therefore, in cloud computing, some protocols use a key manager to encrypt the user’s private data before uploading the data to the cloud. However, the [...] Read more.

Currently, cloud storage servers are controlled by a third-party administrator. This semi-trusted approach gives rise to security concerns. Therefore, in cloud computing, some protocols use a key manager to encrypt the user’s private data before uploading the data to the cloud. However, the security concerns that arise from the use of a key manager are not yet solved. In this respect, in this paper, a provably secure user cloud data access control protocol (DAC) is proposed based on existing cloud storage. Empirical tests confirm that the proposed approach is highly secure against adaptive selective ciphertext attacks and has excellent resistance to message attacks. A comprehensive performance evaluation, including time measurements, is conducted and the protocol is compared to other protocols, revealing the efficient file upload and download processes of the proposed approach. The results demonstrate the protocol’s strong security, practicality, and operational efficiency. Full article

(This article belongs to the Special Issue New Advances in New-Generation Communication and Symmetry)

► Show Figures

Figure 1

15 pages, 4102 KiB

Open AccessArticle

IRS-Assisted Hybrid Secret Key Generation

by Meixiang Zhang, Ziyue Zhuang and Sooyoung Kim

Symmetry 2023, 15(10), 1906; https://doi.org/10.3390/sym15101906 - 12 Oct 2023

Cited by 1 | Viewed by 1409

Abstract

Physical layer secret key (SK) generation is known to be an efficient means to achieve a high secrecy rate, on the condition that dynamic channel state information (CSI) is provided. For this reason, the secrecy performance is highly degraded in a static environment. [...] Read more.

Physical layer secret key (SK) generation is known to be an efficient means to achieve a high secrecy rate, on the condition that dynamic channel state information (CSI) is provided. For this reason, the secrecy performance is highly degraded in a static environment. The intelligent reflecting surface (IRS) is a promising solution to create dynamic randomness, and thus lead to enhanced secrecy performance regardless of the user environments. This paper proposes an IRS-assisted physical layer SK generation scheme, by efficiently combining phase information of the direct and reflected channel information in a hybrid way. In particular, the initial SKs are obtained by adopting an efficient phase quantization method with symmetric bit allocation to complex numbered channel estimates. Simulation results show that the proposed hybrid phase quantization (PQ) can improve the SK generation rate and the key disagreement probability in a static environment. Full article

(This article belongs to the Special Issue New Advances in New-Generation Communication and Symmetry)

► Show Figures

Figure 1

12 pages, 2155 KiB

Open AccessArticle

Newton-like Polynomial-Coded Distributed Computing for Numerical Stability

by Mingjun Dai, Xiong Lai, Yanli Tong and Bingchun Li

Symmetry 2023, 15(7), 1372; https://doi.org/10.3390/sym15071372 - 6 Jul 2023

Cited by 2 | Viewed by 968

Abstract

For coded distributed computing (CDC), polynomial code is one prevalent encoding method for CDC (called Poly-CDC). It suffers from poor numerical stability due to the Vandermonde matrix serving as the coefficient matrix which needs to be inverted, and whose condition number increases exponentially [...] Read more.

For coded distributed computing (CDC), polynomial code is one prevalent encoding method for CDC (called Poly-CDC). It suffers from poor numerical stability due to the Vandermonde matrix serving as the coefficient matrix which needs to be inverted, and whose condition number increases exponentially with the size of the matrix or equivalently with the number of parallel worker nodes. To improve the numerical stability, especially for large networks, we propose a Newton-like polynomial code (NLPC)-based CDC (NLPC-CDC), with a design dedicated for both matrix–vector and matrix–matrix multiplications. The associated proof of the constructed code possesses a

(n, k)

-symmetrical combination property (CP), where symmetrical means the worker nodes have identical computation volume, CP means the k-symmetrical original computing tasks are encoded into

n (n \geq k)

-symmetrically coded computing tasks, and the arbitrary k resulting from the n-coded computing tasks can recover the intended computing results. Extensive numerical studies verify the significant numerical stability improvement of our proposed NLPC-CDC over Poly-CDC. Full article

(This article belongs to the Special Issue New Advances in New-Generation Communication and Symmetry)

► Show Figures

Figure 1

15 pages, 1384 KiB

Open AccessArticle

Review and Evaluation of Belief Propagation Decoders for Polar Codes

by Lingxia Zhou, Meixiang Zhang, Satya Chan and Sooyoung Kim

Symmetry 2022, 14(12), 2633; https://doi.org/10.3390/sym14122633 - 13 Dec 2022

Cited by 4 | Viewed by 2727

Abstract

The polar code has become one of the most popular and important forward error correction (FEC) coding schemes due to its symmetric characteristics of channel polarization. This paper reviews various decoding schemes for polar codes and discusses their advantages and disadvantages. After reviewing [...] Read more.

The polar code has become one of the most popular and important forward error correction (FEC) coding schemes due to its symmetric characteristics of channel polarization. This paper reviews various decoding schemes for polar codes and discusses their advantages and disadvantages. After reviewing the existing performance-enhancing techniques such as belief propagation decoding with list, a new method is proposed to further improve the performance. In addition, a new complexity reduction technique based on the constituent codes is proposed, and a new scheduling scheme is introduced to reduce the decoding latency. Due to the recent development of neural networks, their applications to decoding schemes are also reviewed and evaluated. Finally, the proposed complexity-reduced technique is integrated with a neural network-based belief propagation decoding, which demonstrates performance enhancement as well as computational complexity reduction. Full article

(This article belongs to the Special Issue New Advances in New-Generation Communication and Symmetry)

► Show Figures

Figure 1

22 pages, 6666 KiB

Open AccessArticle

Blind RIS Aided Ordered NOMA: Design, Probability of Outage Analysis and Transmit Power Optimization

by Hindavi Kishor Jadhav and Vinoth Babu Kumaravelu

Symmetry 2022, 14(11), 2266; https://doi.org/10.3390/sym14112266 - 28 Oct 2022

Cited by 8 | Viewed by 1859

Abstract

Non-orthogonal multiple access (NOMA) has been widely acclaimed as a promising solution to enhance spectral efficiency, increase user fairness, and scale up the number of users in wireless networks by enabling multiple users to share the symmetrical wireless resources. This work is concerned [...] Read more.

Non-orthogonal multiple access (NOMA) has been widely acclaimed as a promising solution to enhance spectral efficiency, increase user fairness, and scale up the number of users in wireless networks by enabling multiple users to share the symmetrical wireless resources. This work is concerned with the development and implementation of blind reconfigurable intelligent surface (RIS)-aided ordered NOMA (ONOMA) for smart reflector (SR) and access point (AP) configurations. For the RIS-SR-ONOMA and RIS-AP-ONOMA configurations, the closed-form probability of outage expressions is derived, and their performance is reported for distinct values of passive reflector elements. Through optimal power allocation, the downlink (DL) sum capacity is maximized. RIS-aided ONOMA reduces outage rates and increases sum capacity over the traditional ONOMA system. It is discovered that the RIS-aided ONOMA system increases the sum capacity by ≈33% at 20 dB signal-to-noise ratio (SNR) for 32 passive reflector elements. The addition of passive reflector elements and symmetrical allocation among users improves the performance of RIS-SR-ONOMA and RIS-AP-ONOMA in terms of outage probability, sum capacity, and probability of error. The proposed work can be employed in applications such as vehicular ad hoc networks, where obtaining precise channel information is difficult due to the rapid mobility of the vehicles. Full article

(This article belongs to the Special Issue New Advances in New-Generation Communication and Symmetry)

► Show Figures

Figure 1

14 pages, 4322 KiB

Open AccessArticle

Digital Integration of LiDAR System Implemented in a Low-Cost FPGA

by Jiajian Huang, Shengyao Ran, Wei Wei and Qun Yu

Symmetry 2022, 14(6), 1256; https://doi.org/10.3390/sym14061256 - 17 Jun 2022

Cited by 5 | Viewed by 4267

Abstract

With the development of artificial intelligence, LiDAR finds significant applications in robotics and autonomous driving. Aiming at increasing the compactness and the integration of 2-D LiDAR, this paper presents a highly digitally integrated 2-D LiDAR system implemented in a low-cost FPGA. The system [...] Read more.

With the development of artificial intelligence, LiDAR finds significant applications in robotics and autonomous driving. Aiming at increasing the compactness and the integration of 2-D LiDAR, this paper presents a highly digitally integrated 2-D LiDAR system implemented in a low-cost FPGA. The system is made of off-the-shelf components to limit the cost to USD 100. A laser transceiver with a symmetrical transmitting and receiving lens emits and collects laser pulses to range distance using the time-of-flight (ToF) method. As a key component in ToF, the FPGA-based time-to-digital converter (TDC) is adopted for counting the round-trip time of pulses, which is implemented in a low-cost FPGA of ZYNQ7010 with limited resources. The symmetrical structure of the delay line is used to design a more efficient TDC. The FPGA-TDC enables flexibility of design and integration with more functional logics and is microcontroller-free. All the digital logics including data processing and controlling are integrated into an FPGA with the TDC logics to realize fully digital integration and compact dimensions. The utilization of the whole architecture in the FPGA is about 15%. The experimental results demonstrated that the ranging accuracy of the LiDAR is about 2 cm, which is suitable for consumer electronics. Full article

(This article belongs to the Special Issue New Advances in New-Generation Communication and Symmetry)

► Show Figures

Figure 1

Journal Menu

Journal Browser

New Advances in New-Generation Communication and Symmetry

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (8 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI