Article
Optics
Vineeth Palliyembil, Jagadeesh Vellakudiyan, Palanivel Muthuchidambaranathan
Summary: Free Space Optical (FSO) communication systems are used to provide high-speed, secure, and cost-effective optical connectivity between users through dual hop and asymmetric RF-FSO links. A cooperative system based on the Decode-Forward (DF) relaying method is studied, with generalized channel models considered to derive outage probability and average bit error rate (ABER). Cooperative diversity performance is also investigated by deriving asymptotic expressions for these metrics at high signal-to-noise ratio (SNR).
Article
Engineering, Electrical & Electronic
Muhammad Salman Bashir, Mohamed-Slim Alouini
Summary: This study optimizes the relay positions in a multi-hop unmanned aerial vehicle-based relaying scheme for FSO, resulting in performance improvement by reducing angle-of-arrival variance and pointing error. Specifically, for amplify-and-forward relays with finite power gain, optimizing the outage probability leads to significant performance gains. Moreover, it is found that the optimal hop distance for decode-and-forward relays is inversely proportional to angle-of-arrival variance in low signal-to-noise ratio channels.
IEEE TRANSACTIONS ON COMMUNICATIONS
(2022)
Article
Engineering, Electrical & Electronic
Abdulgani A. Ibrahim, Serdar Ozgur Ata, Lutfiye Durak-Ata
Summary: In this work, spatial diversity techniques are proposed to improve the performance of free-space optical (FSO) communication systems against atmospheric turbulence effects and pointing errors. The performance of FSO communication systems with Alamouti encoding scheme over Malaga turbulence channel is investigated. Analytical expressions for the average bit error rate (BER) and the outage probability (OP) are derived based on the probability distribution function (PDF) of end-to-end channel gain, and asymptotic expressions are also derived. The results highlight the gains in performance that can be achieved when Alamouti encoding scheme is employed in FSO communication systems.
IEEE PHOTONICS JOURNAL
(2022)
Article
Engineering, Electrical & Electronic
Dan Chen, Yuan Liu, Yue Gao, Yeqin Cao
Summary: In this paper, a dynamic adaptive multiple input multiple output (MIMO) free space optical (FSO) system with spatial mode switching is proposed. The system can select different MIMO transmission modes based on channel conditions to maximize average channel capacity and ensure reliable average bit error rate (BER). Closed-form expressions for average channel capacity and average BER are derived for each transmission mode, taking into account path loss, pointing error, and atmospheric turbulence-induced fading modeled by Malaga distribution. Adaptive system performance evaluation results are used to establish a signal-to-noise ratio (SNR) threshold look-up table (LUT) for selecting the optimal transmission mode in different scenarios. Extensive numerical results show that the proposed adaptive system significantly improves average channel capacity compared to stand-alone mode systems. Monte Carlo simulation is also provided to validate the proposed adaptive scheme and conclusions.
IEEE PHOTONICS JOURNAL
(2023)
Article
Remote Sensing
Bing Shen, Jiajia Chen, Guanjun Xu, Qiushi Chen, Jian Wang
Summary: This paper investigates the theoretical performance analysis of a drone-assisted downlink free space optical (FSO) communication system, taking into account atmospheric turbulence. The effects of atmospheric attenuation, pointing errors, and angle-of-arrival fluctuations are characterized using the Malaga distribution. Analytical expressions for the probability density function and cumulative distribution function are derived, and the average bit error rate and ergodic capacity are provided. The asymptotic behavior of the average bit error rate is presented, and the theoretical results are validated through Monte Carlo simulations. The receiver's field-of-view is also analyzed for optimal communication performance.
Article
Telecommunications
Vinay Kumar Chapala, S. M. Zafaruddin
Summary: This study analyzes the performance of a RIS-empowered THz system under the combined effect of alpha-mu fading and pointing errors, providing specific statistical analysis. The results show that RIS can significantly improve the performance of THz communication and offer insights into mitigating pointing errors.
IEEE COMMUNICATIONS LETTERS
(2021)
Article
Computer Science, Information Systems
D. ANANDKUMAR, R. G. SANGEETHA
Summary: In this study, the performance evaluation of LDPC-based MIMO/OFDM FSO link with Malaga channel model is analyzed. The proposed PDF, M-QAM, and Malaga distribution provide closed-form BER derivation, asymptotic BER derivation, and outage probability expression. The proposed MIMO/FSO link offers higher SNR gain and transmission link distance compared to SISO and SIMO FSO links.
Article
Computer Science, Information Systems
Theodore T. Kapsis, Athanasios D. Panagopoulos
Summary: This letter investigates a robust power allocation strategy for the downlink of an optical satellite system, considering the effects of atmospheric impairments and optical beam pointing jitter. Theoretical analysis and maximin optimization problem formulation are used to maximize the worst-case network capacity, and simulation results demonstrate the superiority of the proposed allocation scheme.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2022)
Article
Optics
Basel Mounir El Saghir, Mohamed Bakry El Mashade, Ashraf Mohamed Aboshosha
Summary: The impact of pointing error on the MRR FSO communication system was investigated in this study, with closed-form expressions derived for the probability density function and received optical signal-to-noise ratio statistical characteristics. Analytical results were used to obtain closed-form expressions for system performance metrics like average bit error rate and outage probability.
OPTICS COMMUNICATIONS
(2021)
Article
Optics
Basel Mounir El Saghir, Mohamed Bakry El Mashade, Ashraf Mohamed Aboshosha
Summary: The study focused on the impact of pointing error (PE) on the performance of modulating retro-reflector (MRR) free space optical (FSO) communication system, deriving statistical characteristics and performance expressions. Recommendations for improving system performance were made based on optimizing the beam divergence angle.
OPTICS COMMUNICATIONS
(2021)
Article
Engineering, Electrical & Electronic
Liqiang Han, Xuemei Liu, Yawei Wang, Boyu Li
Summary: This paper provides the performance analysis of free-space optical (FSO) communication systems over Fisher-Snedecor F fading channel with estimation errors in the presence of pointing errors. The probability density function (PDF) and cumulative distribution function (CDF) of signal-to-noise ratio (SNR) are derived in the presence of channel estimation errors and pointing errors. The novel expressions for the outage probability, average bit error rate (BER), and ergodic capacity are obtained. Numerical simulations and Monte Carlo simulations are conducted to analyze the impact of imprecise channel and validate the proposed analysis.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Computer Science, Information Systems
Noor Ahmad Sarker, A. S. M. Badrudduza, S. M. Riazul Islam, Sheikh Habibul Islam, Milton Kumar Kundu, Imran Shafique Ansari, Kyung-Sup Kwak
Summary: This study investigates the secrecy performance of a dual-hop RF-FSO DF relaying network, deriving closed-form analytical expressions and conducting Monte-Carlo simulations for verification. The results demonstrate that fading, shadowing, detection techniques, atmospheric turbulence, and pointing error significantly impact secrecy performance, with better performance achieved using the HD technique compared to the IM/DD technique at the destination.
Article
Engineering, Electrical & Electronic
Bipin K. Saw, Vijay Janyani, Ghanshyam Singh
Summary: This paper analyzes a proposed circular polarized shift keying (CPolSK) for free space optical (FSO) communication system under distribution channel model and Malaga (M) distribution channel model. The proposed system includes two feedback paths for error correction and utilizes optical hybrids for signal mixing. The performance of the system is evaluated under different atmospheric turbulence (AT) conditions, phase noise variance, and polarization control error. The results show that the system's error rate improves with better AT conditions, lower phase noise variance, and decreased polarization control error. The outage probability is also analyzed for different phase noise variances and it is found that the M distribution channel model has a steeper slope compared to the distribution channel model.
OPTICAL AND QUANTUM ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Zhe Xing, Rui Wang, Jun Wu, Erwu Liu
Summary: Intelligent reflecting surface (IRS) is seen as a promising solution to hardware cost and energy consumption in 5G mobile communication networks. However, hardware impairment (HWI) can lead to performance degradation in IRS-aided wireless communication systems. Despite the negative impact of HWI, opportunities exist for IRS to outperform conventional decode-and-forward (DF) relays in certain scenarios.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2021)
Article
Optics
Yidi Chang, Zhi Liu, Haifeng Yao, Shiming Gao, Keyan Dong, Shutong Liu
Summary: This study investigates the multi-hop amplify-and-forward free-space optical communication system in random fog, taking into account the Gamma-Gamma atmospheric turbulence and Beckmann pointing error. Outage probability, average bit error rate, and average ergodic channel capacity are analyzed, and it is found that channel-state-information assisted relay performs better than fixed-gain relay under high transmitted power. Increasing the hop number and optimizing beam width significantly improve the performance of the system.
Article
Engineering, Electrical & Electronic
Dongqing Li, Shaohua Wu, Jian Jiao, Ning Zhang, Qinyu Zhang
Summary: To support freshness-critical applications in the satellite-integrated IoT, it is crucial to transmit information in a timely and reliable manner. However, the long-distance communication in the upcoming satellite-integrated IoT era poses a significant challenge due to non-trivial propagation latency. In this paper, a two-layer coding strategy is proposed to address this issue by incorporating error-correction codes at the packet level and erasure-correction codes across packets. The redundancy compromise between these codes is optimized to achieve an AoI-optimal solution. Simulation results show that this coding scheme improves the timeliness of the system compared to the ultra-reliable PHY-only coding scheme, and the optimal coding rates depend on channel characteristics.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Huanran Li, Shaohua Wu, Jian Jiao, Xiao-Hui Lin, Ning Zhang, Qinyu Zhang
Summary: This paper investigates the autonomous detecting and tracking of UAVs in the maritime environment. It proposes offloading the computation-intensive task to an edge computing server to reduce latency and energy consumption. The impact of video frame resolution on task size, detection accuracy, latency, and energy consumption is examined. Optimization techniques are applied to mitigate the complexity and obtain a low complexity offloading algorithm with good performance.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2023)
Article
Computer Science, Information Systems
Qifan Hu, Jian Jiao, Ye Wang, Shaohua Wu, Rongxing Lu, Qinyu Zhang
Summary: In this article, a multitype services coexistence handover (MSCH) nonorthogonal multiple access (NOMA) scheme for a dual-layer mega LEO satellite constellation is proposed. The scheme can simultaneously and efficiently provide uplink NOMA for three types of fifth-generation user equipments (UEs). Several NOMA algorithms are designed based on the closed-form expressions of three key performance indicators.
IEEE INTERNET OF THINGS JOURNAL
(2023)
Article
Computer Science, Information Systems
Shushi Gu, Zichao Yu, Qinyu Zhang, Tao Huang
Summary: With the rapid development of future networks, the desire for low-energy system design and transmission strategy becomes more compelling. This letter investigates the energy consumption issue of hierarchical cooperative caching networks (HCCNs) and proposes a three-stage coded transmission strategy. A total energy consumption minimization problem is formulated with cache size constraints, and an algorithm is provided to obtain the optimal cache placement matrix. Numerical results demonstrate the effectiveness of the optimized three-stage coded transmission strategy in reducing energy consumption compared to various multicast transmission strategies under different users' cache sizes.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2023)
Article
Telecommunications
Bowen Feng, Yi Yang, Jian Jiao, Qinyu Zhang
Summary: TB-PAC coding is a combination of convolutional codes and polar codes which achieves better BLER performance for short block-length codes when using sequential decoding or large list decoding. However, it doesn't have an advantage when using small list decoding. This letter introduces tailbiting TB-PAC coding with a multi-round list decoding method controlled by early stopping. This small-sizes list decoding improves the BLER performance of TB-PAC codes compared to polar/PAC codes.
IEEE COMMUNICATIONS LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Zhengfu Xu, Kai Li, Qinyu Zhang, Huiling Fu
Summary: The mileage of China's high-speed railways is increasing rapidly, and the current daytime-only operation cannot meet the demand. Overnight trains and maintenance constructions strongly interact with each other and are difficult to coordinate. A double-track one-direction mode on the high-speed railway was proposed to coordinate train operation and maintenance, and a mathematical model and heuristic algorithm were designed and validated. This method provides a new approach to coordinate overnight operation and maintenance of the high-speed railway and increase its capacity.
APPLIED SCIENCES-BASEL
(2023)
Article
Computer Science, Information Systems
Yue Li, Yunlai Xu, Qinyu Zhang, Zhihua Yang
Summary: This article studies a possible solution for remote real-time data gathering using a low orbit satellite constellation as a relay network, where freshness information is forwarded through dynamic intersatellite links. By modeling a time-varying network, the article focuses on minimizing the Age of Information (AoI) in delivering data through a multihop path, particularly considering the effect of frequent interruptions of intersatellite links.
IEEE INTERNET OF THINGS JOURNAL
(2023)
Article
Computer Science, Information Systems
Minkai Zhang, Shaohua Wu, Jian Jiao, Ning Zhang, Qinyu Zhang
Summary: In this article, a networked control system (NCS) with network-induced delay is studied, where the control center controls a remote unmanned aerial vehicle (UAV) for trajectory tracking. The controlled UAV's sensor adopts an event-triggered mechanism, while the control center uses an adaptive dynamic programming (ADP) based tracking control method. Two transmission options are considered, control action or neural network model, and are optimized through a Markov decision process (MDP). A deep Q-network (DQN)-based strategy using reinforcement learning (RL) algorithm is proposed, along with a greedy strategy based on instantaneous expected cost calculation. Simulation results show that the DQN-based strategy performs better but requires training, while the greedy strategy is suboptimal but computationally easier. Moreover, the proposed strategies achieve a better compromise between energy consumption and tracking cost, and the proper transmission sequence in DQN-based strategy can reduce both tracking cost and transmission energy.
IEEE INTERNET OF THINGS JOURNAL
(2023)
Article
Computer Science, Information Systems
Yuhao Huang, Jian Jiao, Ye Wang, Shaohua Wu, Rongxing Lu, Qinyu Zhang
Summary: This article focuses on grant-free massive access setup and analyzes the Age of Information (AoI) in this scenario. A novel graph-based spatially coupled irregular repetition slotted ALOHA (G-SC-IRSA) random access protocol is proposed to improve packet loss rate (PLR) and AoI performance. The article presents theoretical derivations, system load threshold evaluation, and optimal parameter selection for G-SC-IRSA. Simulation results validate the effectiveness of the proposed protocol in achieving minimum AAoI and outperforming existing benchmark schemes.
IEEE INTERNET OF THINGS JOURNAL
(2023)
Article
Biochemistry & Molecular Biology
Bangxi Zhang, Tianhong Fu, Qinyu Zhang, Xiaomin Wang, Ling Tang, Quanquan Wei, Yun Li, Yutao Peng
Summary: This study analyzed the factors influencing the concentration efficiency of forward osmosis (FO) membrane technology in biogas slurry concentration and optimized the operation parameters. The results showed that the concentration effect of the NaCl draw solution was better at pH 5 or 9 compared to pH 7. The factors influencing water flux were draw liquid concentration, cross-flow velocity, and operating temperature. The optimal combination obtained was 45°C with a cross-flow velocity of 1 L/min and the use of 1.5 mol/L NaCl as draw solution. The membrane cleaning results indicated that the fouled membrane had a significantly higher recovery rate (88%) after acid-base cleaning compared to other cleaning solutions. This research provides a scientific reference for the application of forward osmosis technology in re-utilizing biogas slurry resources.
Article
Engineering, Electrical & Electronic
Guanjun Xu, Ning Zhang, Maozhe Xu, Zixuan Xu, Qinyu Zhang, Zhaohui Song
Summary: This paper presents a unified system performance analysis for UAV-assisted dual-hop FSO/FSO systems, considering factors such as attenuation loss, atmospheric turbulence, pointing error impairments, and angle-of-arrival fluctuations. It derives closed-form expressions for the outage probability, average bit error rate, and diversity order of the system. The impact of various system and channel parameters on system performance is studied, and a detailed comparative investigation of modulation schemes is conducted.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Jian Jiao, Hui Hong, Ye Wang, Shaohua Wu, Rongxing Lu, Qinyu Zhang
Summary: In this paper, a satellite-based Internet of Things (S-IoT) scheme is proposed to provide timely updates to terrestrial user equipments (UEs) via non-orthogonal multiple access (NOMA). The system aims to minimize the long-term age of information (AoI) under power and stability constraints, and achieve optimized power allocation using the ListNet algorithm and particle swarm optimization algorithm. Simulation results demonstrate the effectiveness of the proposed scheme in achieving low weighted sum AoI compared to benchmark schemes.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Zhigang Rao, Jian Jiao, Ye Wang, Shaohua Wu, Rongxing Lu, Qinyu Zhang
Summary: In this paper, we propose an LT-collision resolution GFRA (LT-GFRA) scheme for massive access in IoT. Our scheme combines a pilot set and a T-order codebook to allow multiple UEs to access the base station simultaneously. We design a SCJD decoder that can decode at most T UEs from the same pilot and recover up to LT UEs. We analyze the decoding error probability, access failure probability, and system throughput in different fading channels.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2023)
Article
Automation & Control Systems
Yifei Qiu, Shaohua Wu, Jian Jiao, Ning Zhang, Qinyu Zhang
Summary: This article addresses the problem of model-free remote control in a wireless networked cyber-physical system (CPS) consisting of spatially distributed sensors, controllers, and actuators. A deep deterministic policy gradient (DDPG) algorithm is used in the controller to achieve model-free control. The article incorporates historical action information as input and adopts a reward-based prioritized experience replay (PER) approach to improve control accuracy and convergence rate.
IEEE TRANSACTIONS ON CYBERNETICS
(2023)
Article
Computer Science, Information Systems
Jianhao Huang, Jian Jiao, Ye Wang, Shaohua Wu, Rongxing Lu, Qinyu Zhang
Summary: This paper proposes two schemes to achieve dual-hop timely status updates in Satellite Internet of Things (S-IoT). By utilizing long erasure coding and adjusting different modes, it can improve the transmission performance and age of information.
IEEE INTERNET OF THINGS JOURNAL
(2023)
