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
The additional diversity gain provided by the relays improves the secrecy capacity of communications system significantly. The multiple hops in the relaying system is an important technique to improve this diversity g...The additional diversity gain provided by the relays improves the secrecy capacity of communications system significantly. The multiple hops in the relaying system is an important technique to improve this diversity gain. The development of an analytical mathematical model of ensuring security in multicasting through fading channels incorporating this benefit of multi-hop relaying is still an open problem. Motivated by this issue, this paper considers a secure wireless multicasting scenario employing multi-hop relaying technique over frequency selective Nakagami-m fading channel and develops an analytical mathematical model to ensure the security against multiple eavesdroppers. This mathematical model has been developed based on the closed-form analytical expressions of the probability of non-zero secrecy multicast capacity (PNSMC) and the secure outage probability for multicasting (SOPM) to ensure the security in the presence of multiple eavesdroppers. Moreover, the effects of the fading parameter of multicast channel, the number of hops and eavesdropper are investigated. The results show that the security in multicasting through Nakagami-m fading channel with multi-hop relaying system is more sensitive to the number of hops and eavesdroppers. The fading of multicast channel helps to improve the secrecy multicast capacity and is not the enemy of security in multicasting.展开更多
Implementing quantum wireless multi-hop network communication is essential to improve the global quantum network system. In this paper, we employ eight-level GHZ states as quantum channels to realize multi-hop quantum...Implementing quantum wireless multi-hop network communication is essential to improve the global quantum network system. In this paper, we employ eight-level GHZ states as quantum channels to realize multi-hop quantum communication, and utilize the logical relationship between the measurements of each node to derive the unitary operation performed by the end node. The hierarchical simultaneous entanglement switching(HSES) method is adopted, resulting in a significant reduction in the consumption of classical information compared to multi-hop quantum teleportation(QT)based on general simultaneous entanglement switching(SES). In addition, the proposed protocol is simulated on the IBM Quantum Experiment platform(IBM QE). Then, the data obtained from the experiment are analyzed using quantum state tomography, which verifies the protocol's good fidelity and accuracy. Finally, by calculating fidelity, we analyze the impact of four different types of noise(phase-damping, amplitude-damping, phase-flip and bit-flip) in this protocol.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
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
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
卫星下行链路因其开放性、广域覆盖性而面临严峻的窃听威胁,传统以加密技术为核心的卫星下行链路防窃听方案在计算复杂度与抗量子攻击能力上存在双重瓶颈,且现有卫星下行链路物理层安全防窃听方案的应用场景存在局限性。针对以上问题,...卫星下行链路因其开放性、广域覆盖性而面临严峻的窃听威胁,传统以加密技术为核心的卫星下行链路防窃听方案在计算复杂度与抗量子攻击能力上存在双重瓶颈,且现有卫星下行链路物理层安全防窃听方案的应用场景存在局限性。针对以上问题,通过基于动态扩展因子的扰码与编码级联设计,提出一种基于信道状态信息(Channel State Information,CSI)和协作中继的卫星下行链路防窃听方案。首先,通过部署地面中继基站,建立基于协作中继的卫星下行链路通信模型,扩大合法链路与窃听链路的CSI随机性差异;其次,通过合法链路CSI对准循环低密度奇偶校验码扩展因子进行动态调控,增加编码随机性,进而增加窃听者译码难度;最后,通过动态扩展因子与合法链路CSI在卫星端与用户端构建加扰与解扰机制,使窃听者因缺乏合法链路CSI而无法解扰保密信息。仿真结果表明,在用户端误码率低至10-6的情况下,利用扰码对CSI的依赖性构建窃听者解扰壁垒,可使窃听者误码率接近0.5。所提方案凭借对CSI与地面协作中继的协同设计,既具备抵御量子计算攻击的潜在能力,又契合卫星通信网络工程部署对高效低耗的需求,能够有效平衡卫星下行链路信息传输可靠性与安全性的矛盾,可为未来6G空天地一体化场景下的信息安全传输提供具备工程实践价值的技术参考路径。展开更多
为解决某批次纯电动车型行驶中突发动力中断故障问题,本文以该车型高压正极继电器失效案例为研究对象,通过诊断仪数据采集、部件对比试验、系统环境排查等方法,明确故障根本原因为继电器触点氧化粘连与机械卡滞。高压配电单元(Power Dis...为解决某批次纯电动车型行驶中突发动力中断故障问题,本文以该车型高压正极继电器失效案例为研究对象,通过诊断仪数据采集、部件对比试验、系统环境排查等方法,明确故障根本原因为继电器触点氧化粘连与机械卡滞。高压配电单元(Power Distribution Unit,PDU)密封缺陷导致潮气侵入,引发触点电解氧化及接触点电阻增大,高温环境加剧氧化循环进而造成触点粘连;支架吸潮膨胀与杂质堆积则导致机械卡滞。针对上述问题,本文提出“部件升级+结构优化+程序改进”的综合应对方案,包括更换抗氧化触点继电器、升级PDU密封构件、优化整车控制器VCU控制逻辑。整改结果显示,继电器电寿命提升66.7%,相关故障实现“零投诉”,验证了该方案的有效性。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
Cognitive radio networks(CRNs) are expected to improve spectrum utilization efficiently by allowing secondary users(SUs) to opportunistically access the licensed spectrum of primary users(PUs).In CRNs,source and desti...Cognitive radio networks(CRNs) are expected to improve spectrum utilization efficiently by allowing secondary users(SUs) to opportunistically access the licensed spectrum of primary users(PUs).In CRNs,source and destination SUs may achieve information interaction in an ad hoc manner.In the case that no direct transmission link between the SU transmission pairs is available,multi-hop relay SUs can be applied to forward information for the source and destination SUs,resulting in multi-hop CRNs.In this paper,we consider a multi-hop CRN consisting of multiple PUs,SU transmission pairs and relay SUs.Stressing the importance of transmission hops and the tradeoff between data rate and power consumption,we propose an energy efficient constrained shortest path first(CSPF)-based joint resource allocation and route selection algorithm,which consists of two sub-algorithms,i.e.,CSPF-based route selection sub-algorithm and energy efficient resource allocation sub-algorithm.More specifically,we first apply CSPF-based route selection sub-algorithm to obtain the shortest candidate routes(SCRs) between the SU pair under the transmission constraints.Then,an energy efficient resource allocation problem of the SCRs is formulated and solved by applying iterative algorithm and Lagrange dual method.Simu-lation results demonstrate the effectiveness of the proposed algorithm.展开更多
Abts ract A wireless mutl i-hop videot ransmission experiment system is designed and implemented for vehiculra ad-hoc networks VANET and the rt ansm ission control protocol and routing protocol are proposed. This syst...Abts ract A wireless mutl i-hop videot ransmission experiment system is designed and implemented for vehiculra ad-hoc networks VANET and the rt ansm ission control protocol and routing protocol are proposed. This system in tegrates the embedded Linux system witha n ARM kernel and oc ns ists of a S3C6410 main control module a wirel ss local arean etwork WLAN card a LCD screne and so on.In the scenario of a wireless multi-hop video transmission both the H.264 and JPEG are used and their performances such as the compression rate delay and frame loss rate are analyzed in theory andc ompared in the experiment.The system is tested in the real indoor and outdoor environment.The results show that the scheme of the multi-hop video transmission experiment system can be applicable for VANET and multiple scenes and the transmission control protocol and routing protocol proposed can achieve real-time transmission and meet multi-hop requirements.展开更多
In this paper, we consider a full.duplex multiple.input multiple.output(MIMO) relaying network with the decode.and.forward(DF) protocol. Due to the full.duplex transmissions, the self.interference from the relay trans...In this paper, we consider a full.duplex multiple.input multiple.output(MIMO) relaying network with the decode.and.forward(DF) protocol. Due to the full.duplex transmissions, the self.interference from the relay transmitter to the relay receiver degrades the system performance. We thus propose an iterative beamforming structure(IBS) to mitigate the self.interference. In this method, the receive beamforming at the relay is optimized to maximize the signal.to.interference.plus.noise.ratio(Max.SINR), while the transmit beamforming at the relay is optimized to maximize the signal.to.leakage.plusnoise.ratio(Max.SLNR). To further improve the performance, the receive and transmit beamforming matrices are optimized between Max.SINR and Max.SLNR in an iterative manner. Furthermore, in the presence of the residual self.interference, a low.complexity whitening.filter(WF) maximum likelihood(ML) detector is proposed. In this detector, a WF is designed to transform a colored interference.plus.noise to a white noise, while the singular value decomposition is used to convert coupled spatial subchannels to parallelindependent ones. From simulations, we find that the proposed IBS performs much better than the existing schemes. Also, the proposed low.complexity detector significantly reduces the complexity of the conventional ML(CML) detector from exponential time(an exponential function of the number of the source transmit antennas) to polynomial one while achieving a slightly better BER performance than the CML due to interference whitening.展开更多
Cooperation allows wireless network users to benefit from various gains such as an in- crease in the achieved rate or an improvement in the bit error rate. In the paper, we propose a distributed Hierarchical Game （HG...Cooperation allows wireless network users to benefit from various gains such as an in- crease in the achieved rate or an improvement in the bit error rate. In the paper, we propose a distributed Hierarchical Game （HG） theoretic framework over multi-user cooperative communication networks to stimulate cooperation and improve the network performance. First, we study a two- user decision making game in the OFDMA based subscriber cooperative relaying network, in which subscribers transmit their own data in the first phase, while helping to retransmit their partner＇s or choosing to freeride in the second phase. Instead of consulting to a global optimal solution, we decouple the cooperation resource allocation into two level subproblems： a user level Nash game for distributed cooperation decision and a Base Station （BS） level coalition game for centralized resource allocation. In the proposed HG algorithm, where mutual cooperation is preferred and total payoff is transferable, we prove it converges to a unique optimal equilibrium and resolve the subcarrier as-signment and power allocation among the couples. Besides, we discuss the existence of the publishing and rewarding coefficients in order to encourage cooperation. Then, we extend the HG to multi-user cases by coupling among subscribers according to the location information. The simulation results show that the proposed scheme with the distributed HG game achieves a well tradeoff between fairness and efficiency by improving the transmission efficiency of adverse users and outperforms those employing centralized schemes.展开更多
Multi-hop teleportation has significant value due to long-distance delivery of quantum information. Many studies about multi-hop teleportation are based on Bell pairs, partially entangled pairs or W state. The possibi...Multi-hop teleportation has significant value due to long-distance delivery of quantum information. Many studies about multi-hop teleportation are based on Bell pairs, partially entangled pairs or W state. The possibility of multi-hop teleportation constituted by partially entangled pairs relates to the number of nodes. The possibility of multi-hop teleportation constituted by double W states is （4/9）~n after n-hop teleportation. In this paper, a multi-hop teleportation scheme based on W state and EPR pairs is presented and proved. The successful possibility of quantum information transmitted hop by hop through intermediate nodes is deduced. The possibility of successful transmission is （2/3）~n after n-hop teleportation.展开更多
The minimum energy per bit(EPB)as the energy efficiency(EE)metric in an automatic retransmission request(ARQ)based multi-hop system is analyzed under power and throughput constraints.Two ARQ protocols including type-I...The minimum energy per bit(EPB)as the energy efficiency(EE)metric in an automatic retransmission request(ARQ)based multi-hop system is analyzed under power and throughput constraints.Two ARQ protocols including type-I(ARQ-I)and repetition redundancy(ARQ-RR)are considered and expressions for the optimal power allocation(PA)are obtained.Using the obtained optimal powers,the EE-throughput tradeoff(EETT)is analyzed and the EETT closed-form expressions for both ARQ protocols and in arbitrary average channel gain values are obtained.It is shown that how different throughput requirements,especially the high levels,affect the EE performance.Additionally,asymptotic analysis is made in the feasible high throughput values and lower and upper EETT bounds are derived for ARQ-I protocol.To evaluate the EE a distributed PA scenario,as a benchmark,is presented and the energy savinggain obtained from the optimal PA in comparison with the distributed PA for ARQ-I and ARQ-RR protocols is discussed in different throughput values and node locations.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
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The additional diversity gain provided by the relays improves the secrecy capacity of communications system significantly. The multiple hops in the relaying system is an important technique to improve this diversity gain. The development of an analytical mathematical model of ensuring security in multicasting through fading channels incorporating this benefit of multi-hop relaying is still an open problem. Motivated by this issue, this paper considers a secure wireless multicasting scenario employing multi-hop relaying technique over frequency selective Nakagami-m fading channel and develops an analytical mathematical model to ensure the security against multiple eavesdroppers. This mathematical model has been developed based on the closed-form analytical expressions of the probability of non-zero secrecy multicast capacity (PNSMC) and the secure outage probability for multicasting (SOPM) to ensure the security in the presence of multiple eavesdroppers. Moreover, the effects of the fading parameter of multicast channel, the number of hops and eavesdropper are investigated. The results show that the security in multicasting through Nakagami-m fading channel with multi-hop relaying system is more sensitive to the number of hops and eavesdroppers. The fading of multicast channel helps to improve the secrecy multicast capacity and is not the enemy of security in multicasting.
基金Project supported by the Open Fund of Anhui Key Laboratory of Mine Intelligent Equipment and Technology (Grant No. ZKSYS202204)the Talent Introduction Fund of Anhui University of Science and Technology (Grant No. 2021yjrc34)the Scientific Research Fund of Anhui Provincial Education Department (Grant No. KJ2020A0301)。
文摘Implementing quantum wireless multi-hop network communication is essential to improve the global quantum network system. In this paper, we employ eight-level GHZ states as quantum channels to realize multi-hop quantum communication, and utilize the logical relationship between the measurements of each node to derive the unitary operation performed by the end node. The hierarchical simultaneous entanglement switching(HSES) method is adopted, resulting in a significant reduction in the consumption of classical information compared to multi-hop quantum teleportation(QT)based on general simultaneous entanglement switching(SES). In addition, the proposed protocol is simulated on the IBM Quantum Experiment platform(IBM QE). Then, the data obtained from the experiment are analyzed using quantum state tomography, which verifies the protocol's good fidelity and accuracy. Finally, by calculating fidelity, we analyze the impact of four different types of noise(phase-damping, amplitude-damping, phase-flip and bit-flip) in this protocol.
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.
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.
文摘卫星下行链路因其开放性、广域覆盖性而面临严峻的窃听威胁,传统以加密技术为核心的卫星下行链路防窃听方案在计算复杂度与抗量子攻击能力上存在双重瓶颈,且现有卫星下行链路物理层安全防窃听方案的应用场景存在局限性。针对以上问题,通过基于动态扩展因子的扰码与编码级联设计,提出一种基于信道状态信息(Channel State Information,CSI)和协作中继的卫星下行链路防窃听方案。首先,通过部署地面中继基站,建立基于协作中继的卫星下行链路通信模型,扩大合法链路与窃听链路的CSI随机性差异;其次,通过合法链路CSI对准循环低密度奇偶校验码扩展因子进行动态调控,增加编码随机性,进而增加窃听者译码难度;最后,通过动态扩展因子与合法链路CSI在卫星端与用户端构建加扰与解扰机制,使窃听者因缺乏合法链路CSI而无法解扰保密信息。仿真结果表明,在用户端误码率低至10-6的情况下,利用扰码对CSI的依赖性构建窃听者解扰壁垒,可使窃听者误码率接近0.5。所提方案凭借对CSI与地面协作中继的协同设计,既具备抵御量子计算攻击的潜在能力,又契合卫星通信网络工程部署对高效低耗的需求,能够有效平衡卫星下行链路信息传输可靠性与安全性的矛盾,可为未来6G空天地一体化场景下的信息安全传输提供具备工程实践价值的技术参考路径。
文摘为解决某批次纯电动车型行驶中突发动力中断故障问题,本文以该车型高压正极继电器失效案例为研究对象,通过诊断仪数据采集、部件对比试验、系统环境排查等方法,明确故障根本原因为继电器触点氧化粘连与机械卡滞。高压配电单元(Power Distribution Unit,PDU)密封缺陷导致潮气侵入,引发触点电解氧化及接触点电阻增大,高温环境加剧氧化循环进而造成触点粘连;支架吸潮膨胀与杂质堆积则导致机械卡滞。针对上述问题,本文提出“部件升级+结构优化+程序改进”的综合应对方案,包括更换抗氧化触点继电器、升级PDU密封构件、优化整车控制器VCU控制逻辑。整改结果显示,继电器电寿命提升66.7%,相关故障实现“零投诉”,验证了该方案的有效性。
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.
基金supported by the National Science and Technology Specific Project of China(2016ZX03001010-004)National Natural Science Foundation of China(6140105361571073)+2 种基金the Joint Scientifi c Research Fund Ministry of Education and China Mobile(MCM20160105)the special fund of Chongqing key laboratory(CSTC)the project of Chongqing Municipal Education Commission(Kjzh11206)
文摘Cognitive radio networks(CRNs) are expected to improve spectrum utilization efficiently by allowing secondary users(SUs) to opportunistically access the licensed spectrum of primary users(PUs).In CRNs,source and destination SUs may achieve information interaction in an ad hoc manner.In the case that no direct transmission link between the SU transmission pairs is available,multi-hop relay SUs can be applied to forward information for the source and destination SUs,resulting in multi-hop CRNs.In this paper,we consider a multi-hop CRN consisting of multiple PUs,SU transmission pairs and relay SUs.Stressing the importance of transmission hops and the tradeoff between data rate and power consumption,we propose an energy efficient constrained shortest path first(CSPF)-based joint resource allocation and route selection algorithm,which consists of two sub-algorithms,i.e.,CSPF-based route selection sub-algorithm and energy efficient resource allocation sub-algorithm.More specifically,we first apply CSPF-based route selection sub-algorithm to obtain the shortest candidate routes(SCRs) between the SU pair under the transmission constraints.Then,an energy efficient resource allocation problem of the SCRs is formulated and solved by applying iterative algorithm and Lagrange dual method.Simu-lation results demonstrate the effectiveness of the proposed algorithm.
基金The National Natural Science Foundation of China(No.61201175,61171081)Transformation Program of Science and Technology Achievements of Jiangsu Province(No.BA2010023)
文摘Abts ract A wireless mutl i-hop videot ransmission experiment system is designed and implemented for vehiculra ad-hoc networks VANET and the rt ansm ission control protocol and routing protocol are proposed. This system in tegrates the embedded Linux system witha n ARM kernel and oc ns ists of a S3C6410 main control module a wirel ss local arean etwork WLAN card a LCD screne and so on.In the scenario of a wireless multi-hop video transmission both the H.264 and JPEG are used and their performances such as the compression rate delay and frame loss rate are analyzed in theory andc ompared in the experiment.The system is tested in the real indoor and outdoor environment.The results show that the scheme of the multi-hop video transmission experiment system can be applicable for VANET and multiple scenes and the transmission control protocol and routing protocol proposed can achieve real-time transmission and meet multi-hop requirements.
基金supported in part by the National Natural Science Foundation of China (Nos. 61271230, 61472190, and 61501238)the Open Research Fund of National Key Laboratory of Electromagnetic Environment, China Research Institute of Radiowave Propagation (No. 201500013)+4 种基金the open research fund of National Mobile Communications Research Laboratory, Southeast University, China (No. 2013D02)the Research Fund for the Doctoral Program of Higher Education of China (No. 20113219120019)the Foundation of Cloud Computing and Big Data for Agriculture and Forestry (117-612014063)the China Postdoctoral Science Foundation (2016M591852)Postdoctoral research funding program of Jiangsu Province (1601257C)
文摘In this paper, we consider a full.duplex multiple.input multiple.output(MIMO) relaying network with the decode.and.forward(DF) protocol. Due to the full.duplex transmissions, the self.interference from the relay transmitter to the relay receiver degrades the system performance. We thus propose an iterative beamforming structure(IBS) to mitigate the self.interference. In this method, the receive beamforming at the relay is optimized to maximize the signal.to.interference.plus.noise.ratio(Max.SINR), while the transmit beamforming at the relay is optimized to maximize the signal.to.leakage.plusnoise.ratio(Max.SLNR). To further improve the performance, the receive and transmit beamforming matrices are optimized between Max.SINR and Max.SLNR in an iterative manner. Furthermore, in the presence of the residual self.interference, a low.complexity whitening.filter(WF) maximum likelihood(ML) detector is proposed. In this detector, a WF is designed to transform a colored interference.plus.noise to a white noise, while the singular value decomposition is used to convert coupled spatial subchannels to parallelindependent ones. From simulations, we find that the proposed IBS performs much better than the existing schemes. Also, the proposed low.complexity detector significantly reduces the complexity of the conventional ML(CML) detector from exponential time(an exponential function of the number of the source transmit antennas) to polynomial one while achieving a slightly better BER performance than the CML due to interference whitening.
基金Acknowledgements This work is supported by the National Natural Science Foundation of China under Grant No. 60971083, National High-Tech Research and Development Plan of China under Grant No. 2009AA01Z206 and National International Science and Technology Cooperation Project under Granted NO.2008DFA12090.
文摘Cooperation allows wireless network users to benefit from various gains such as an in- crease in the achieved rate or an improvement in the bit error rate. In the paper, we propose a distributed Hierarchical Game （HG） theoretic framework over multi-user cooperative communication networks to stimulate cooperation and improve the network performance. First, we study a two- user decision making game in the OFDMA based subscriber cooperative relaying network, in which subscribers transmit their own data in the first phase, while helping to retransmit their partner＇s or choosing to freeride in the second phase. Instead of consulting to a global optimal solution, we decouple the cooperation resource allocation into two level subproblems： a user level Nash game for distributed cooperation decision and a Base Station （BS） level coalition game for centralized resource allocation. In the proposed HG algorithm, where mutual cooperation is preferred and total payoff is transferable, we prove it converges to a unique optimal equilibrium and resolve the subcarrier as-signment and power allocation among the couples. Besides, we discuss the existence of the publishing and rewarding coefficients in order to encourage cooperation. Then, we extend the HG to multi-user cases by coupling among subscribers according to the location information. The simulation results show that the proposed scheme with the distributed HG game achieves a well tradeoff between fairness and efficiency by improving the transmission efficiency of adverse users and outperforms those employing centralized schemes.
基金Project supported by the National Natural Science Foundation of China(Grant No.61571105)the Prospective Future Network Project of Jiangsu Province,China(Grant No.BY2013095-1-18)the Independent Project of State Key Laboratory of Millimeter Waves,China(Grant No.Z201504)
文摘Multi-hop teleportation has significant value due to long-distance delivery of quantum information. Many studies about multi-hop teleportation are based on Bell pairs, partially entangled pairs or W state. The possibility of multi-hop teleportation constituted by partially entangled pairs relates to the number of nodes. The possibility of multi-hop teleportation constituted by double W states is （4/9）~n after n-hop teleportation. In this paper, a multi-hop teleportation scheme based on W state and EPR pairs is presented and proved. The successful possibility of quantum information transmitted hop by hop through intermediate nodes is deduced. The possibility of successful transmission is （2/3）~n after n-hop teleportation.
文摘The minimum energy per bit(EPB)as the energy efficiency(EE)metric in an automatic retransmission request(ARQ)based multi-hop system is analyzed under power and throughput constraints.Two ARQ protocols including type-I(ARQ-I)and repetition redundancy(ARQ-RR)are considered and expressions for the optimal power allocation(PA)are obtained.Using the obtained optimal powers,the EE-throughput tradeoff(EETT)is analyzed and the EETT closed-form expressions for both ARQ protocols and in arbitrary average channel gain values are obtained.It is shown that how different throughput requirements,especially the high levels,affect the EE performance.Additionally,asymptotic analysis is made in the feasible high throughput values and lower and upper EETT bounds are derived for ARQ-I protocol.To evaluate the EE a distributed PA scenario,as a benchmark,is presented and the energy savinggain obtained from the optimal PA in comparison with the distributed PA for ARQ-I and ARQ-RR protocols is discussed in different throughput values and node locations.
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.
