This paper investigates the secure communication between legitimate users in the presence of eavesdroppers, where the Intelligent Reflective Surface-Unmanned Aerial Vehicle (IRS-UAV) and Buffer-Aided (BA) relaying tec...This paper investigates the secure communication between legitimate users in the presence of eavesdroppers, where the Intelligent Reflective Surface-Unmanned Aerial Vehicle (IRS-UAV) and Buffer-Aided (BA) relaying techniques are utilized to enhance secrecy performance. By jointly optimizing the link selection strategy, the UAV position, and the reflection coefficient of the IRS, we aim to maximize the long-term average secrecy rate. Specifically, we propose a novel buffer in/out stabilization scheme based on the Lyapunov framework, which transforms the long-term average secrecy rate maximization problem into two per-slot drift-plus-penalty minimization problems with different link selection factors. The hybrid Particle Swarm Optimization-Artificial Fish Swarm Algorithm (PSO-AFSA) is adopted to optimize the UAV position, and the IRS reflection coefficient optimization problem is solved by iterative optimization in which auxiliary variables and standard convex optimization algorithms are introduced. Finally, the delay constraint is set to ensure the timeliness of information packets. Simulation results demonstrate that our proposed scheme outperforms the comparison schemes in terms of average secrecy rate. Specifically, the addition of BA improves the average secrecy rate by 1.37 bps/Hz, and the continued optimizations of IRS reflection coefficients and UAV positions improve the average secrecy rate by 2.46 bps/Hz and 3.75 bps/Hz, respectively.展开更多
Serving multiple cell-edge mobile terminals poses multifaceted challenges due to the increased transmission power and interferences, which could be overcome by relay communications. With the recent advancement of 5G t...Serving multiple cell-edge mobile terminals poses multifaceted challenges due to the increased transmission power and interferences, which could be overcome by relay communications. With the recent advancement of 5G technologies, non-orthogonal multiple access(NOMA) has been used at relay node to transmit multiple messages simultaneously to multiple cell-edge users. In this paper, a Collaborative NOMA Assisted Relaying(CNAR) system for 5G is proposed by enabling the collaboration of source-relay(S-R) and relay-destination(R-D) NOMA links. The relay node of the CNAR decodes the message for itself from S-R NOMA signal and transmits the remaining messages to the multiple cell-edge users in R-D link. A simplified-CNAR(S-CNAR) system is then developed to reduce the relay complexity. The outage probabilities for both systems are analyzed by considering outage behaviors in S-R and R-D links separately. To guarantee the data rate, the optimal power allocation among NOMA users is achieved by minimizing the outage probability. The ergodic sum capacity in high SNR regime is also approximated. Our mathematical analysis and simulation results show that CNAR system outperforms existing transmission strategies and S-CNAR reaches similar performance with much lower complexity.展开更多
With the development of large-scale complicated modern power systems, the requirement for the associated protection scheme tends to be more stringent and its combination more complex. However, it is very difficult to ...With the development of large-scale complicated modern power systems, the requirement for the associated protection scheme tends to be more stringent and its combination more complex. However, it is very difficult to figure out the factors of failure of such systems. This paper proposes a Petri net model of a transmission line protection relaying system, including three types of relays as well as an automatic reclosing device, and shows how to diagnose serial failure of the system by analyzing invariant sets of the model. Furthermore, it gives four basic types of failure sequences and its execution is much more intuitive and effective than the traditional method.展开更多
In this paper,we investigate the performance of the two-way Amplify-and-Forward(AF) relaying systems in an interference-limited Rayleigh fading environment.More specifically,assuming the presence of Rayleigh faded mul...In this paper,we investigate the performance of the two-way Amplify-and-Forward(AF) relaying systems in an interference-limited Rayleigh fading environment.More specifically,assuming the presence of Rayleigh faded multiple interferers at the AF relay and noisy sources,an approximate closed-form expression for the Overall Outage Probability(OOP) and an integral expression for the average Symbol Error Probability(SEP) are derived.The analysis results are verified through com-parison with the Monte Carlo simulation results.展开更多
Cooperative relaying for a system that consists of different configurations of a collocated and uniform linear antenna is analyzed. The amplify-and-forward relaying (AF) and selection combining (S-AF) schemes based on...Cooperative relaying for a system that consists of different configurations of a collocated and uniform linear antenna is analyzed. The amplify-and-forward relaying (AF) and selection combining (S-AF) schemes based on maximal ratio combining (MRC) method for single- and multi-relay are investigated. In this study, the bit-error-rate (BER) expression for collocated and uniform linear antenna in cooperative communication system over flat Rayleigh fading channel is derived. The result for 3-element collocated antennas (tripole) shows improvement in performance over dual-polarized antennas. Also increasing number of tripole antenna does not add improvement.展开更多
In Power Line Communications(PLC),there are regulatory masks that restrict the transmit power spectral density for electromagnetic compatibility reasons,which creates coverage issues despite the not too long distances...In Power Line Communications(PLC),there are regulatory masks that restrict the transmit power spectral density for electromagnetic compatibility reasons,which creates coverage issues despite the not too long distances.Hence,PLC networks often employ repeaters/relays,especially in smart grid neighborhood area networks.Even in broadband indoor PLC systems that offer a notable data rate,relaying may pave the way to new applications like being the backbone for wireless technologies in a cost-effective manner to support the Internet-of-things paradigm.In this paper,we study Multiple-Input Multiple-Output(MIMO)PLC systems that incorporate inband full-duplex functionality in relaying networks.We present several MIMO configurations that allow end-to-end half-duplex or full-duplex operations and analyze the achievable performance with state-of-the-art PLC systems.To reach this analysis,we get channel realizations from random network layouts for indoor and outdoor scenarios.We adopt realistic MIMO channel and noise models and consider transmission techniques according to PLC standards.The concepts discussed in this work can be useful in the design of future PLC relay-aided networks for different applications that look for a coverage extension and/or throughput:smart grids with enhanced communications in outdoor scenarios,and“last meter”systems for high-speed connections everywhere in indoor ones.展开更多
A novel scheme‘user assisted cooperative relaying in beamspace massive multiple input multiple output(M-MIMO)non-orthogonal multiple access(NOMA)system’has been proposed to improve coverage area,spectrum and energy ...A novel scheme‘user assisted cooperative relaying in beamspace massive multiple input multiple output(M-MIMO)non-orthogonal multiple access(NOMA)system’has been proposed to improve coverage area,spectrum and energy efficiency for millimeter wave(mmWave)communications.A downlink system for M users,where base station(BS)is equipped with beamforming lens antenna structure having NRF radio frequency(RF)chains,has been considered.A dynamic cluster of users is formed within a beam and the intermediate users(in that cluster)between beam source and destination(user)act as relaying stations.By the use of successive interference cancellation(SIC)technique of NOMA within a cluster,the relaying stations relay the symbols with improved power to the destination.For maximizing achievable sum rate,transmit precoding and dynamic power allocation for both intra and inter beam power optimization are implemented.Simulations for performance evaluation are carried out to validate that the proposed system outperforms the conventional beamspace M-MIMO NOMA system for mmWave communications in terms of spectrum and energy efficiency.展开更多
This paper proposes rate-maximized （MR） joint subcarrier pairing （SP） and power allocation （PA） （MR-SP＆PA）, a novel scheme for maximizing the weighted sum rate of the orthogonal-frequency-division multiplexi...This paper proposes rate-maximized （MR） joint subcarrier pairing （SP） and power allocation （PA） （MR-SP＆PA）, a novel scheme for maximizing the weighted sum rate of the orthogonal-frequency-division multiplexing （OFDM） relaying system with a decode-and-forward （DF） relay. MR-SP＆PA is based on the joint optimization of both SP and power allocation with total power constraint, and formulated as a mixed integer programming problem in the paper. The programming problem is then transformed to a convex optimization problem by using continuous relaxation, and solved in the Lagrangian dual domain. Simulation results show that MR-SP＆PA can maximize the weighted sum rate under total power constraint and outperform equal power allocation （EPA） and proportion power allocation （PCG）.展开更多
In this paper, the system performance of a decode-and-forward(DF) full-duplex(FD) adaptive relaying network over the Rician fading environment is proposed, analyzed and demonstrated. In the first stage, the system is ...In this paper, the system performance of a decode-and-forward(DF) full-duplex(FD) adaptive relaying network over the Rician fading environment is proposed, analyzed and demonstrated. In the first stage, the system is presented with the energy harvesting and information transmission processes. After that, the analytical expressions of the achievable throughput, the outage probability, and symbol error ratio(SER) were proposed, analyzed and demonstrated. Finally, the analytical results are also demonstrated by Monte-Carlo simulation in comparison with the closed-form expressions in the influence of the key system parameters. The results show that the analytical and simulated results match for all possible parameter values.展开更多
An improved distributed turbo coding （DTC） scheme, namely, systematic-bit-selection DTC, is proposed for a two-hop relay network implementing selective-relaying （SR）. In the scheme, source broadcasts a punctured t...An improved distributed turbo coding （DTC） scheme, namely, systematic-bit-selection DTC, is proposed for a two-hop relay network implementing selective-relaying （SR）. In the scheme, source broadcasts a punctured turbo code in order to increase the successful decoding rate of relay. The relay forwards systematic-bit to the destination in case of successful cyclic redundancy check （CRC）. From the two versions of systematic-bit coming from relay and source respectively, the des- tination selects the one with higher signal-to-noise ratio （SNR） for turbo decoding. Simulation re- suits show the improved bit error rate （BER） performance of our scheme.展开更多
There were two sessions and onepanel discussion on relaying pro-tection at the conference,with participantsfrom Australia,Canada,Japan,Korea,arepresentative of the well known relaymanufacturer ABB and from the host co...There were two sessions and onepanel discussion on relaying pro-tection at the conference,with participantsfrom Australia,Canada,Japan,Korea,arepresentative of the well known relaymanufacturer ABB and from the host coun-try China.The papers presented at thesessions covered a large variety of subjectsrelated to protection,including novel pro-tection principles and schemes。展开更多
In recent years,the demands of high traffic transmission motivate the rapid development of wireless access techniques,and it becomes promising to design the fifth generation(5G)wireless networks.Essential requirements...In recent years,the demands of high traffic transmission motivate the rapid development of wireless access techniques,and it becomes promising to design the fifth generation(5G)wireless networks.Essential requirements for 5G involve higher traffic volume,indoor or hotspot traffic,and spectrum,energy,and cost efficien-cy.展开更多
With the rapid development of the smart grid, it is necessary to do good corresponding work in relaying protection so as to meet the overall requirements of the smart grid better. So we must focus on the state divisio...With the rapid development of the smart grid, it is necessary to do good corresponding work in relaying protection so as to meet the overall requirements of the smart grid better. So we must focus on the state division, risk analysis and fault diagnosis methods in the relaying protection system, in the basis of fully understanding the advantages and disadvantages of relaying protection system, and then improve the problems existing of relaying protection system at this stage according to the actual situation. This paper aims at the overview of analysis on state evaluation of relaying protection systems.展开更多
The rapid evolution of Fifth-Generation(5G)networks and the strategic development of Sixth-Generation(6G)technologies have significantly advanced the implementation of air-ground integrated networks with seamless cove...The rapid evolution of Fifth-Generation(5G)networks and the strategic development of Sixth-Generation(6G)technologies have significantly advanced the implementation of air-ground integrated networks with seamless coverage.Unmanned Aerial Vehicles(UAVs),serving as high-mobility aerial platforms,are extensively utilized to enhance coverage in long-distance emergency communication scenarios.The resource-constrained communication environments in emergencies by classifying UAVs into swarm UAVs and relay UAVs as aerial communication nodes is inversitgated.A horizontal deployment strategy for swarm UAVs is formulated through K-means clustering algorithm optimization,while a vertical deployment scheme is established using convex optimization methods.The minimum-path trajectory planning for relay UAVs is optimized via the Particle Swarm Optimization(PSO)algorithm,enhancing communication reliability between UAV swarms and terrestrial base stations.A three-dimensional heterogeneous network architecture is realized by modeling spatial multi-hop relay links.Experimental results demonstrate that the proposed joint UAV relay optimization framework outperforms conventional algorithms in both coverage performance and relay capability during video stream transmission,achieving significant improvements in coverage enhancement and relay efficiency.This work provides technical foundations for constructing high-reliability air-ground cooperative systems in emergency communications.展开更多
The present work is a discussion on the performance analysis of Modified Cooperative Subchannel Allocation (CSA) Algorithms which is used in Alamouti Decoded and Forward (Alamouti DF) Relaying Protocol for wireless mu...The present work is a discussion on the performance analysis of Modified Cooperative Subchannel Allocation (CSA) Algorithms which is used in Alamouti Decoded and Forward (Alamouti DF) Relaying Protocol for wireless multi-user Orthogonal Frequency Division Multiplexing Access (OFDMA) systems. In addition, the performance of approximate Symbol Error Rate (SER) for the Alamouti DF Relaying Protocol with the Cooperative Maximum Ratio Combining Technique (C-MRC) is analyzed and compared with SER upper bound. The approximate SER is asymptotically tight bound at higher Signal-to-Noise Ratio (SNR). From the asymptotic tight bound approximate SER, Particle Swarm Optimization (PSO) based Power Allocation (PA) is determined for the Alamouti DF Relaying Protocol. The simulation results suggested that the Modified Throughput based Subchannel Allocation Algorithm achieved an improved throughput of 6% to 33% compared to that of existing cooperative diversity protocol. Further, the Modified Fairness based Subchannel Allocation Algorithm rendered fairness of 7.2% to 17% among the multiuser against the existing cooperative diversity protocol.展开更多
A Reconfigurable Intelligent Surface(RIS)can relay signals from the transmitter to the receiver.In this regard,RISs operate similarly to traditional relays.We design a Multiple-Input-Multiple-Output(MIMO)system with a...A Reconfigurable Intelligent Surface(RIS)can relay signals from the transmitter to the receiver.In this regard,RISs operate similarly to traditional relays.We design a Multiple-Input-Multiple-Output(MIMO)system with a hybrid network of RIS and Half-Duplex(HD)Amplify-and-Forward(AF)relay.We model the system’s signal propagation and propose a new algorithm to get the system’s Achievable Rate(AR)value.We complete simulations to evaluate the performance of the RIS and HD-AF relay hybrid network system compared to the system assisted by either the RIS or HD-AF relay.The simulations indicate that many factors can considerably influence the system performance.Selecting an optimal placement for the RIS and relay can result in the best performance for the RIS and HD-AF relay hybrid network system in situations where the direct link between the receiver and transmitter is absent.展开更多
With the continuous improvement of current science and technology and residents’electricity demand,the power system relay protection course has become a key component of the curriculum for students majoring in power ...With the continuous improvement of current science and technology and residents’electricity demand,the power system relay protection course has become a key component of the curriculum for students majoring in power engineering.In this context,the teaching model of power system relay protection faces both new challenges and opportunities.By integrating the Outcome-Based Education(OBE)concept,teachers can reconstruct curriculum objectives and teaching frameworks by clearly defining learning outcomes,thereby enhancing students’practical competencies and innovative thinking.Based on the core connotation of the OBE concept,this paper analyzes the significance of incorporating OBE into Power System Relay Protection teaching and explores effective implementation strategies.The findings aim to offer practical insights for teaching reform and to strengthen the alignment between academic training and industry requirements.展开更多
Physical layer security methods based on joint relay and jammer selection(JRJS)have been widely investigated in the study of secure wireless communications.Different from current works on JRJS schemes,which assumed th...Physical layer security methods based on joint relay and jammer selection(JRJS)have been widely investigated in the study of secure wireless communications.Different from current works on JRJS schemes,which assumed that the global channel state information(CSI)of the eavesdroppers(Eves)was known beforehand,then the optimal relaying and jamming relays were determined.More importantly,the time complexity of selecting optimal jamming relay is O(N^(2)),where N is the maximum number of relays/Eves.In this paper,for the scenario where the source wants to exchange the message with the destination,via relaying scheme due to longer communication distance and limited transmission power,in the presence of multiple Eves,with the assumption of Eves'perfect CSI and average CSI,we propose two kinds of JRJS methods.In particular,the time complexity of finding the optimal jammer can be reduced to O(N).Furthermore,we present a novel JRJS scheme for no CSI of Eves by minimizing the difference between expected signal and interfering signal at the destination.Finally,simulations show that the designed methods are more effective than JRJS and other existing strategies in terms of security performance.展开更多
In this study,a solution based on deep Q network(DQN)is proposed to address the relay selection problem in cooperative non-orthogonal multiple access(NOMA)systems.DQN is particularly effective in addressing problems w...In this study,a solution based on deep Q network(DQN)is proposed to address the relay selection problem in cooperative non-orthogonal multiple access(NOMA)systems.DQN is particularly effective in addressing problems within dynamic and complex communication environ-ments.By formulating the relay selection problem as a Markov decision process(MDP),the DQN algorithm employs deep neural networks(DNNs)to learn and make decisions through real-time interactions with the communication environment,aiming to minimize the system’s outage proba-bility.During the learning process,the DQN algorithm progressively acquires channel state infor-mation(CSI)between two nodes,thereby minimizing the system’s outage probability until a sta-ble level is reached.Simulation results show that the proposed method effectively reduces the out-age probability by 82%compared to the two-way relay selection scheme(Two-Way)when the sig-nal-to-noise ratio(SNR)is 30 dB.This study demonstrates the applicability and advantages of the DQN algorithm in cooperative NOMA systems,providing a novel approach to addressing real-time relay selection challenges in dynamic communication environments.展开更多
In this paper, a multi-hop relay channel model based on unmanned aerial vehicles(UAVs) is established by taking into account of the propagation loss, shadowing, and multi-path fading. Based on the proposed channel mod...In this paper, a multi-hop relay channel model based on unmanned aerial vehicles(UAVs) is established by taking into account of the propagation loss, shadowing, and multi-path fading. Based on the proposed channel model, the cascaded propagation loss of relay link and the cascaded probability density function(PDF) of channel fading are derived. Moreover, the theoretical performance of the UAV-based relay system, i.e., the outage probability, bit error rate(BER), and channel capacity, is also analysed and derived. Simulation results show agreement with theoretical results for the hill, mountain, and sea scenarios, indicating the accuracy of both the simulations and derivations.展开更多
基金co-supported by the National Natural Science Foundation of China(Nos.62271399,61901015,GNA22001 and GAA20024)the Zhejiang Provincial Natural Science Foundation of China(No.LQ24F010003).
文摘This paper investigates the secure communication between legitimate users in the presence of eavesdroppers, where the Intelligent Reflective Surface-Unmanned Aerial Vehicle (IRS-UAV) and Buffer-Aided (BA) relaying techniques are utilized to enhance secrecy performance. By jointly optimizing the link selection strategy, the UAV position, and the reflection coefficient of the IRS, we aim to maximize the long-term average secrecy rate. Specifically, we propose a novel buffer in/out stabilization scheme based on the Lyapunov framework, which transforms the long-term average secrecy rate maximization problem into two per-slot drift-plus-penalty minimization problems with different link selection factors. The hybrid Particle Swarm Optimization-Artificial Fish Swarm Algorithm (PSO-AFSA) is adopted to optimize the UAV position, and the IRS reflection coefficient optimization problem is solved by iterative optimization in which auxiliary variables and standard convex optimization algorithms are introduced. Finally, the delay constraint is set to ensure the timeliness of information packets. Simulation results demonstrate that our proposed scheme outperforms the comparison schemes in terms of average secrecy rate. Specifically, the addition of BA improves the average secrecy rate by 1.37 bps/Hz, and the continued optimizations of IRS reflection coefficients and UAV positions improve the average secrecy rate by 2.46 bps/Hz and 3.75 bps/Hz, respectively.
文摘Serving multiple cell-edge mobile terminals poses multifaceted challenges due to the increased transmission power and interferences, which could be overcome by relay communications. With the recent advancement of 5G technologies, non-orthogonal multiple access(NOMA) has been used at relay node to transmit multiple messages simultaneously to multiple cell-edge users. In this paper, a Collaborative NOMA Assisted Relaying(CNAR) system for 5G is proposed by enabling the collaboration of source-relay(S-R) and relay-destination(R-D) NOMA links. The relay node of the CNAR decodes the message for itself from S-R NOMA signal and transmits the remaining messages to the multiple cell-edge users in R-D link. A simplified-CNAR(S-CNAR) system is then developed to reduce the relay complexity. The outage probabilities for both systems are analyzed by considering outage behaviors in S-R and R-D links separately. To guarantee the data rate, the optimal power allocation among NOMA users is achieved by minimizing the outage probability. The ergodic sum capacity in high SNR regime is also approximated. Our mathematical analysis and simulation results show that CNAR system outperforms existing transmission strategies and S-CNAR reaches similar performance with much lower complexity.
文摘With the development of large-scale complicated modern power systems, the requirement for the associated protection scheme tends to be more stringent and its combination more complex. However, it is very difficult to figure out the factors of failure of such systems. This paper proposes a Petri net model of a transmission line protection relaying system, including three types of relays as well as an automatic reclosing device, and shows how to diagnose serial failure of the system by analyzing invariant sets of the model. Furthermore, it gives four basic types of failure sequences and its execution is much more intuitive and effective than the traditional method.
基金Supported by the National Natural Science Foundation of China (No. 61001107)the Important National Science & Technology Specific Project (2010ZX03006-002-04)the Natural Science Foundation of Jiangsu Province (No.BK2010101)
文摘In this paper,we investigate the performance of the two-way Amplify-and-Forward(AF) relaying systems in an interference-limited Rayleigh fading environment.More specifically,assuming the presence of Rayleigh faded multiple interferers at the AF relay and noisy sources,an approximate closed-form expression for the Overall Outage Probability(OOP) and an integral expression for the average Symbol Error Probability(SEP) are derived.The analysis results are verified through com-parison with the Monte Carlo simulation results.
文摘Cooperative relaying for a system that consists of different configurations of a collocated and uniform linear antenna is analyzed. The amplify-and-forward relaying (AF) and selection combining (S-AF) schemes based on maximal ratio combining (MRC) method for single- and multi-relay are investigated. In this study, the bit-error-rate (BER) expression for collocated and uniform linear antenna in cooperative communication system over flat Rayleigh fading channel is derived. The result for 3-element collocated antennas (tripole) shows improvement in performance over dual-polarized antennas. Also increasing number of tripole antenna does not add improvement.
基金supported by the Spanish Government and EU,under project PID2019-109842RB-I00/AEI/10.13039/501100011033。
文摘In Power Line Communications(PLC),there are regulatory masks that restrict the transmit power spectral density for electromagnetic compatibility reasons,which creates coverage issues despite the not too long distances.Hence,PLC networks often employ repeaters/relays,especially in smart grid neighborhood area networks.Even in broadband indoor PLC systems that offer a notable data rate,relaying may pave the way to new applications like being the backbone for wireless technologies in a cost-effective manner to support the Internet-of-things paradigm.In this paper,we study Multiple-Input Multiple-Output(MIMO)PLC systems that incorporate inband full-duplex functionality in relaying networks.We present several MIMO configurations that allow end-to-end half-duplex or full-duplex operations and analyze the achievable performance with state-of-the-art PLC systems.To reach this analysis,we get channel realizations from random network layouts for indoor and outdoor scenarios.We adopt realistic MIMO channel and noise models and consider transmission techniques according to PLC standards.The concepts discussed in this work can be useful in the design of future PLC relay-aided networks for different applications that look for a coverage extension and/or throughput:smart grids with enhanced communications in outdoor scenarios,and“last meter”systems for high-speed connections everywhere in indoor ones.
文摘A novel scheme‘user assisted cooperative relaying in beamspace massive multiple input multiple output(M-MIMO)non-orthogonal multiple access(NOMA)system’has been proposed to improve coverage area,spectrum and energy efficiency for millimeter wave(mmWave)communications.A downlink system for M users,where base station(BS)is equipped with beamforming lens antenna structure having NRF radio frequency(RF)chains,has been considered.A dynamic cluster of users is formed within a beam and the intermediate users(in that cluster)between beam source and destination(user)act as relaying stations.By the use of successive interference cancellation(SIC)technique of NOMA within a cluster,the relaying stations relay the symbols with improved power to the destination.For maximizing achievable sum rate,transmit precoding and dynamic power allocation for both intra and inter beam power optimization are implemented.Simulations for performance evaluation are carried out to validate that the proposed system outperforms the conventional beamspace M-MIMO NOMA system for mmWave communications in terms of spectrum and energy efficiency.
基金supported by the National Key Technology R&D Program (2008BAH30B10)the National Natural Science Foundation of China (60972070)+1 种基金the Chongqing Municipal Science & Technology Development Program,China (CSTC2010A-C2143)the Natural Science Foundation of Chongqing,China (CSTC2009B-A2090)
文摘This paper proposes rate-maximized （MR） joint subcarrier pairing （SP） and power allocation （PA） （MR-SP＆PA）, a novel scheme for maximizing the weighted sum rate of the orthogonal-frequency-division multiplexing （OFDM） relaying system with a decode-and-forward （DF） relay. MR-SP＆PA is based on the joint optimization of both SP and power allocation with total power constraint, and formulated as a mixed integer programming problem in the paper. The programming problem is then transformed to a convex optimization problem by using continuous relaxation, and solved in the Lagrangian dual domain. Simulation results show that MR-SP＆PA can maximize the weighted sum rate under total power constraint and outperform equal power allocation （EPA） and proportion power allocation （PCG）.
文摘In this paper, the system performance of a decode-and-forward(DF) full-duplex(FD) adaptive relaying network over the Rician fading environment is proposed, analyzed and demonstrated. In the first stage, the system is presented with the energy harvesting and information transmission processes. After that, the analytical expressions of the achievable throughput, the outage probability, and symbol error ratio(SER) were proposed, analyzed and demonstrated. Finally, the analytical results are also demonstrated by Monte-Carlo simulation in comparison with the closed-form expressions in the influence of the key system parameters. The results show that the analytical and simulated results match for all possible parameter values.
文摘An improved distributed turbo coding （DTC） scheme, namely, systematic-bit-selection DTC, is proposed for a two-hop relay network implementing selective-relaying （SR）. In the scheme, source broadcasts a punctured turbo code in order to increase the successful decoding rate of relay. The relay forwards systematic-bit to the destination in case of successful cyclic redundancy check （CRC）. From the two versions of systematic-bit coming from relay and source respectively, the des- tination selects the one with higher signal-to-noise ratio （SNR） for turbo decoding. Simulation re- suits show the improved bit error rate （BER） performance of our scheme.
文摘There were two sessions and onepanel discussion on relaying pro-tection at the conference,with participantsfrom Australia,Canada,Japan,Korea,arepresentative of the well known relaymanufacturer ABB and from the host coun-try China.The papers presented at thesessions covered a large variety of subjectsrelated to protection,including novel pro-tection principles and schemes。
文摘In recent years,the demands of high traffic transmission motivate the rapid development of wireless access techniques,and it becomes promising to design the fifth generation(5G)wireless networks.Essential requirements for 5G involve higher traffic volume,indoor or hotspot traffic,and spectrum,energy,and cost efficien-cy.
文摘With the rapid development of the smart grid, it is necessary to do good corresponding work in relaying protection so as to meet the overall requirements of the smart grid better. So we must focus on the state division, risk analysis and fault diagnosis methods in the relaying protection system, in the basis of fully understanding the advantages and disadvantages of relaying protection system, and then improve the problems existing of relaying protection system at this stage according to the actual situation. This paper aims at the overview of analysis on state evaluation of relaying protection systems.
文摘The rapid evolution of Fifth-Generation(5G)networks and the strategic development of Sixth-Generation(6G)technologies have significantly advanced the implementation of air-ground integrated networks with seamless coverage.Unmanned Aerial Vehicles(UAVs),serving as high-mobility aerial platforms,are extensively utilized to enhance coverage in long-distance emergency communication scenarios.The resource-constrained communication environments in emergencies by classifying UAVs into swarm UAVs and relay UAVs as aerial communication nodes is inversitgated.A horizontal deployment strategy for swarm UAVs is formulated through K-means clustering algorithm optimization,while a vertical deployment scheme is established using convex optimization methods.The minimum-path trajectory planning for relay UAVs is optimized via the Particle Swarm Optimization(PSO)algorithm,enhancing communication reliability between UAV swarms and terrestrial base stations.A three-dimensional heterogeneous network architecture is realized by modeling spatial multi-hop relay links.Experimental results demonstrate that the proposed joint UAV relay optimization framework outperforms conventional algorithms in both coverage performance and relay capability during video stream transmission,achieving significant improvements in coverage enhancement and relay efficiency.This work provides technical foundations for constructing high-reliability air-ground cooperative systems in emergency communications.
文摘The present work is a discussion on the performance analysis of Modified Cooperative Subchannel Allocation (CSA) Algorithms which is used in Alamouti Decoded and Forward (Alamouti DF) Relaying Protocol for wireless multi-user Orthogonal Frequency Division Multiplexing Access (OFDMA) systems. In addition, the performance of approximate Symbol Error Rate (SER) for the Alamouti DF Relaying Protocol with the Cooperative Maximum Ratio Combining Technique (C-MRC) is analyzed and compared with SER upper bound. The approximate SER is asymptotically tight bound at higher Signal-to-Noise Ratio (SNR). From the asymptotic tight bound approximate SER, Particle Swarm Optimization (PSO) based Power Allocation (PA) is determined for the Alamouti DF Relaying Protocol. The simulation results suggested that the Modified Throughput based Subchannel Allocation Algorithm achieved an improved throughput of 6% to 33% compared to that of existing cooperative diversity protocol. Further, the Modified Fairness based Subchannel Allocation Algorithm rendered fairness of 7.2% to 17% among the multiuser against the existing cooperative diversity protocol.
文摘A Reconfigurable Intelligent Surface(RIS)can relay signals from the transmitter to the receiver.In this regard,RISs operate similarly to traditional relays.We design a Multiple-Input-Multiple-Output(MIMO)system with a hybrid network of RIS and Half-Duplex(HD)Amplify-and-Forward(AF)relay.We model the system’s signal propagation and propose a new algorithm to get the system’s Achievable Rate(AR)value.We complete simulations to evaluate the performance of the RIS and HD-AF relay hybrid network system compared to the system assisted by either the RIS or HD-AF relay.The simulations indicate that many factors can considerably influence the system performance.Selecting an optimal placement for the RIS and relay can result in the best performance for the RIS and HD-AF relay hybrid network system in situations where the direct link between the receiver and transmitter is absent.
文摘With the continuous improvement of current science and technology and residents’electricity demand,the power system relay protection course has become a key component of the curriculum for students majoring in power engineering.In this context,the teaching model of power system relay protection faces both new challenges and opportunities.By integrating the Outcome-Based Education(OBE)concept,teachers can reconstruct curriculum objectives and teaching frameworks by clearly defining learning outcomes,thereby enhancing students’practical competencies and innovative thinking.Based on the core connotation of the OBE concept,this paper analyzes the significance of incorporating OBE into Power System Relay Protection teaching and explores effective implementation strategies.The findings aim to offer practical insights for teaching reform and to strengthen the alignment between academic training and industry requirements.
基金supported by the National Natural Science Foundation of China with Grants 62301076 and 62321001。
文摘Physical layer security methods based on joint relay and jammer selection(JRJS)have been widely investigated in the study of secure wireless communications.Different from current works on JRJS schemes,which assumed that the global channel state information(CSI)of the eavesdroppers(Eves)was known beforehand,then the optimal relaying and jamming relays were determined.More importantly,the time complexity of selecting optimal jamming relay is O(N^(2)),where N is the maximum number of relays/Eves.In this paper,for the scenario where the source wants to exchange the message with the destination,via relaying scheme due to longer communication distance and limited transmission power,in the presence of multiple Eves,with the assumption of Eves'perfect CSI and average CSI,we propose two kinds of JRJS methods.In particular,the time complexity of finding the optimal jammer can be reduced to O(N).Furthermore,we present a novel JRJS scheme for no CSI of Eves by minimizing the difference between expected signal and interfering signal at the destination.Finally,simulations show that the designed methods are more effective than JRJS and other existing strategies in terms of security performance.
基金supported by the National Natural Science Foundation of China(Nos.61841107 and 62061024)Gansu Natural Sci-ence Foundation(Nos.22JR5RA274 and 23YFGA0062)Gansu Innovation Foundation(No.2022A-215).
文摘In this study,a solution based on deep Q network(DQN)is proposed to address the relay selection problem in cooperative non-orthogonal multiple access(NOMA)systems.DQN is particularly effective in addressing problems within dynamic and complex communication environ-ments.By formulating the relay selection problem as a Markov decision process(MDP),the DQN algorithm employs deep neural networks(DNNs)to learn and make decisions through real-time interactions with the communication environment,aiming to minimize the system’s outage proba-bility.During the learning process,the DQN algorithm progressively acquires channel state infor-mation(CSI)between two nodes,thereby minimizing the system’s outage probability until a sta-ble level is reached.Simulation results show that the proposed method effectively reduces the out-age probability by 82%compared to the two-way relay selection scheme(Two-Way)when the sig-nal-to-noise ratio(SNR)is 30 dB.This study demonstrates the applicability and advantages of the DQN algorithm in cooperative NOMA systems,providing a novel approach to addressing real-time relay selection challenges in dynamic communication environments.
基金supported by the National Key Scientific Instrument and Equipment Development Project(Grant No.2013YQ200607)China NSF Grants(Grant No.61631020)+2 种基金Aeronautical Science Foundation of China(Grant No.2017ZC52021)Fundamental Research Funds for the Central Universities(Grant No.NJ20160027)Open Foundation for Graduate Innovation of NUAA(Grant No.kfjj20160412 and kfjj20170405)
文摘In this paper, a multi-hop relay channel model based on unmanned aerial vehicles(UAVs) is established by taking into account of the propagation loss, shadowing, and multi-path fading. Based on the proposed channel model, the cascaded propagation loss of relay link and the cascaded probability density function(PDF) of channel fading are derived. Moreover, the theoretical performance of the UAV-based relay system, i.e., the outage probability, bit error rate(BER), and channel capacity, is also analysed and derived. Simulation results show agreement with theoretical results for the hill, mountain, and sea scenarios, indicating the accuracy of both the simulations and derivations.
