In covert communications,joint jammer selection and power optimization are important to improve performance.However,existing schemes usually assume a warden with a known location and perfect Channel State Information(...In covert communications,joint jammer selection and power optimization are important to improve performance.However,existing schemes usually assume a warden with a known location and perfect Channel State Information(CSI),which is difficult to achieve in practice.To be more practical,it is important to investigate covert communications against a warden with uncertain locations and imperfect CSI,which makes it difficult for legitimate transceivers to estimate the detection probability of the warden.First,the uncertainty caused by the unknown warden location must be removed,and the Optimal Detection Position(OPTDP)of the warden is derived which can provide the best detection performance(i.e.,the worst case for a covert communication).Then,to further avoid the impractical assumption of perfect CSI,the covert throughput is maximized using only the channel distribution information.Given this OPTDP based worst case for covert communications,the jammer selection,the jamming power,the transmission power,and the transmission rate are jointly optimized to maximize the covert throughput(OPTDP-JP).To solve this coupling problem,a Heuristic algorithm based on Maximum Distance Ratio(H-MAXDR)is proposed to provide a sub-optimal solution.First,according to the analysis of the covert throughput,the node with the maximum distance ratio(i.e.,the ratio of the distances from the jammer to the receiver and that to the warden)is selected as the friendly jammer(MAXDR).Then,the optimal transmission and jamming power can be derived,followed by the optimal transmission rate obtained via the bisection method.In numerical and simulation results,it is shown that although the location of the warden is unknown,by assuming the OPTDP of the warden,the proposed OPTDP-JP can always satisfy the covertness constraint.In addition,with an uncertain warden and imperfect CSI,the covert throughput provided by OPTDP-JP is 80%higher than the existing schemes when the covertness constraint is 0.9,showing the effectiveness of OPTDP-JP.展开更多
Jammers can awfully interfere with the wireless communications. The transmission and reception of wireless communication is blocked by the jammer. The intruder will place the jammer in a well topological network area ...Jammers can awfully interfere with the wireless communications. The transmission and reception of wireless communication is blocked by the jammer. The intruder will place the jammer in a well topological network area and they can easily track the information. It will help them to block the signal transmission and reception. Now, the intention is to track the position of the jammer where it is fixed. The existing methods rely on the indirect measurements and the boundary node to find the jammer’s position which degrades the accuracy of the localization. To improve the efficiency, this paper proposed an efficient method namely Coincered Node Based Localization of jammers to find the position of the jammer with high level of accuracy. The proposed system uses the direct measurements, which is the jammer signal strength. The effectiveness can also be increased by using the coincered node that will stumble across the true position of the jammer. The proposed work is compared with existing methods. Then the proposed mechanism proves better to find the jammer location. The simulation results estimate that the accuracy of the localization achieves better performance than the existing schemes.展开更多
This paper mainly investigates the coordinated anti-jamming channel access problems in multiuser scenarios where there exists a tracking jammer who senses the spectrum and traces the channel with maximal receiving pow...This paper mainly investigates the coordinated anti-jamming channel access problems in multiuser scenarios where there exists a tracking jammer who senses the spectrum and traces the channel with maximal receiving power.To cope with the challenges brought by the tracking jammer,a multi-leader onefollower anti-jamming Stackelberg(MOAS)game is formulated,which is able to model the complex interactions between users and the tracking jammer.In the proposed game,users act as leaders,chose their channel access strategies and transmit firstly.The tracking jammer acts as the follower,whose objective is to find the optimal jamming strategy at each time slot.Besides,the existence of Stackelberg equilibriums(SEs)is proved,which means users reach Nash Equilibriums(NEs)for each jamming strategy while the jammer finds its best response jamming strategy for the current network access case.An active attraction based anti-jamming channel access(3ACA)algorithm is designed to reach SEs,where jammed users keep their channel access strategies unchanged to create access chances for other users.To enhance the fairness of the system,users will adjust their strategies and relearn after certain time slots to provide access chances for those users who sacrifice themselves to attract the tracking jammer.展开更多
In this paper,we investigate covert communications in data collected IoT with NOMA,where the paired sensor nodes S_(m) and S_(n) transmit covert messages to a legitimate receiver(Bob)in the presence of a Warden(Willie...In this paper,we investigate covert communications in data collected IoT with NOMA,where the paired sensor nodes S_(m) and S_(n) transmit covert messages to a legitimate receiver(Bob)in the presence of a Warden(Willie).To confuse the detection at Willie,an extra multi-antenna friendly jammer(Jammer)has been employed to transmit artificial noise(AN)with random power.Based on the CSI of Willie is available or not at Jammer,three AN transmission schemes,including null-space artificial noise(NAN),transmit antenna selection(TAS),and zeroforcing beamforming(ZFB),are proposed.Furthermore,the closed-form expressions of expected minimum detection error probability(EMDEP)and joint connection outage probability(JCOP)are derived to measure covertness and reliability,respectively.Finally,the maximum effective covert rate(ECR)is obtained with a given covertness constraint.The numerical results show that ZFB scheme has the best maximum ECR in the case of the number of antennas satisfies N>2,and the same maximum ECR can be achieved in ZFB and NAN schemes with N=2.Moreover,TAS scheme also can improve the maximum ECR compared with the benchmark scheme(i.e.,signal-antenna jammer).In addition,a proper NOMA node pairing can further improve the maximum ECR.展开更多
To further promote the achievable average secrecy rate for UAV-ground communications, a UAV-aided mobile jamming strategy was proposed in this paper. Specifically, an additional cooperative UAV is employed as a mobile...To further promote the achievable average secrecy rate for UAV-ground communications, a UAV-aided mobile jamming strategy was proposed in this paper. Specifically, an additional cooperative UAV is employed as a mobile jammer to transmit the jamming signal to help keep the source UAV closer to the ground destination, thus establishing more favorable legitimate link and enhancing the secrecy performance. We aimed to maximize the achievable secrecy rate by jointly optimizing the trajectories and transmit power of both source UAV and jammer UAV. To solve the considered non-convex optimization problem, we presented a block coordinate descent based iterative algorithm to address a sequence of approximated convex problems for the optimized parameter block by block to find a local optimal solution. Numerical results verify that the proposed algorithm can achieve significant secrecy rate gain compared to all the benchmark schemes.展开更多
Objective:To evaluate the effect of long-term exposure to radiofrequency radiations emitted from mobile jammers onrat's reproductive parameters.Methods: Eighty male rats were divided into neonatal group (n=20), im...Objective:To evaluate the effect of long-term exposure to radiofrequency radiations emitted from mobile jammers onrat's reproductive parameters.Methods: Eighty male rats were divided into neonatal group (n=20), immature group (n=30) and mature group (n=30). Neonatal rats were randomly divided into two subgroups. Immature and mature rats were randomly divided into three subgroups. Experimental rats were fixed in the restraining tube and were exposed to radiofrequency radiations emitted from mobile jammers at a distance of 100 cm, for 30 d (7 h/d). Sham group rats were also fixed in restraining tube but without radiations. The control group was allowed to move freely without being exposed to radiation. At the end of the experiment, weight of testes, sperm quality, histological testicular sections and serum testosterone levels were evaluated.Results: Long-term exposure to radiofrequency from mobile jammers could adversely affect neonatal rat fertility, but it did not have significant effects on male mature and immature rat's reproduction parameters. However, restraint stress induced by immobilizing them for a long-period could adversely affect male mature rat's reproductive parameters, but it had no significant effect on male immature rat's reproduction parameters.Conclusion:The effects of EMF exposure to be various based on the life stage.展开更多
In wireless sensor networks （WSNs）, as the shared nature of the wireless medium, jam- ming attacks can be easily launched and result in a great damage to the network. How to deal with jamming attacks has become a gr...In wireless sensor networks （WSNs）, as the shared nature of the wireless medium, jam- ming attacks can be easily launched and result in a great damage to the network. How to deal with jamming attacks has become a great concern recently. Finding the location of a jammer is important to take security actions against the jammer, and thus to restore the network communication. After a comprehensive study on the jammer localization problem, a lightweight easy-operated algorithm called triple circles localization （TCL） is proposed. The evaluation results have demonstrated that, compared with other approaches, TCL achieves the best jammer localization accuracy under variable conditions.展开更多
In this work,we investigate the covert communication in cognitive radio(CR)networks with the existence of multiple cognitive jammers(CJs).Specifically,the secondary transmitter(ST)helps the primary transmitter(PT)to r...In this work,we investigate the covert communication in cognitive radio(CR)networks with the existence of multiple cognitive jammers(CJs).Specifically,the secondary transmitter(ST)helps the primary transmitter(PT)to relay information to primary receiver(PR),as a reward,the ST can use PT's spectrum to transmit private information against the eavesdropper(Eve)under the help of one selected cognitive jammer(CJ).Meanwhile,we propose three jammer-selection schemes,namely,link-oriented jammer selection(LJS),min-max jammer selection(MMJS)and random jammer selection(RJS).For each scheme,we analyze the average covert throughput(ACT)and covert outage probability(COP).Our simulation results show that CJ is helpful to ST's covert communication,the expected minimum detection error probability and ACT can be significantly improved with the increase of false alarm of CJ.Moreover,the LJS scheme achieves best performance in ACT and COP,followed by RJS scheme,and MMJS scheme shows the worst performance.展开更多
In this paper,the detection capabilities and system performance of an energy harvesting(EH)Internet of Things(Io T)architecture in the presence of an unmanned aerial vehicle(UAV)eavesdropper(UE)are investigated.The co...In this paper,the detection capabilities and system performance of an energy harvesting(EH)Internet of Things(Io T)architecture in the presence of an unmanned aerial vehicle(UAV)eavesdropper(UE)are investigated.The communication protocol is divided into two phases.In the first phase,a UAV relay(UR)cooperates with a friendly UAV jammer(UJ)to detect the UE,and the UR and UJ harvest energy from a power beacon(PB).In the second phase,a ground base station(GBS)sends a confidential signal to the UR using non-orthogonal multiple access(NOMA);the UR then uses its harvested energy to forward this confidential signal to IoT destinations(IDs)using the decode-and-forward(DF)technique.Simultaneously,the UJ uses its harvested energy to emit an artificial signal to combat the detected UE.A closed-form expression for the probability of detecting the UE(the detection probability,DP)is derived to analyze the detection performance.Furthermore,the intercept probability(IP)and throughput of the considered IoT architecture are determined.Accordingly,we identify the optimal altitudes for the UR and UJ to enhance the system and secrecy performance.Monte Carlo simulations are employed to verify our approach.展开更多
Abstract：Aiming at achieving better Quality of Service （QoS） provisioning in distributed wireless cooperative networks, a novel energy efficient jammer selection approach is proposed in this pa per. We employ Secre...Abstract：Aiming at achieving better Quality of Service （QoS） provisioning in distributed wireless cooperative networks, a novel energy efficient jammer selection approach is proposed in this pa per. We employ Secrecy Capacity （SC） to charac terize the security of transmission. In order to ac curately describe the timevarying characteristic, related channels are modeled as FiniteState M ark ov Channels （FSMCs）. The remaining energy of candidate node is considered in a similar way.展开更多
Localizing a jammer in an indoor environment in wireless sensor networks becomes a significant research problem due to the ease of blocking the communication between legitimate nodes. An adversary may emit radio frequ...Localizing a jammer in an indoor environment in wireless sensor networks becomes a significant research problem due to the ease of blocking the communication between legitimate nodes. An adversary may emit radio frequency to prevent the transmission between nodes. In this paper, we propose detecting the position of the jammer indoor by using the received signal strength and Kalman filter (KF) to reduce the noise due to the multipath signal caused by obstacles in the indoor environment. We compare our work to the Linear Prediction Algorithm (LP) and Centroid Localization Algorithm (CL). We observed that the Kalman filter has better results when estimating the distance compared to other algorithms.展开更多
In wireless networks, jamming attacks are easy to launch and can significantly impact the network performance. The technique which localizes the jamming attacker is useful to address this problem. Some range-based loc...In wireless networks, jamming attacks are easy to launch and can significantly impact the network performance. The technique which localizes the jamming attacker is useful to address this problem. Some range-based localization schemes depend on the additional hardware of wireless nodes too much, and they can not work in resource-constrained wireless networks. Solutions in range-free localization are being pursued as a cost-effective alternative to more expensive range-based approaches.In this paper, we propose a novel range-free algorithm to localize the source of the attacker. We show that our approach only relies on the positions of each jammed or no-jammed node in the network, PSO algorithm is used to get the minimum covering circle of jammed positions and the circle center is the estimated jammer location. We compare our work with some existing range-free solutions via extensive simulations in two models, which are wireless sensor network (WSN) and vehicular ad hoc network (VANET) respectively. The experimental results suggest that our proposed algorithm achieves higher accuracy than the other solutions, and the localization error goes down with larger number of recorded jammed positions. In additional, when the recorded jammed positions are distributed in a specific constrained area, the localization error goes higher, we also propose an improved PSO algorithm to deal with this issue.展开更多
To deal with the threat of the new generation of electronic warfare,we establish a non-cooperative countermeasure game model to analyze power allocation and interference suppression between multistatic multipleinput m...To deal with the threat of the new generation of electronic warfare,we establish a non-cooperative countermeasure game model to analyze power allocation and interference suppression between multistatic multipleinput multiple-output(MIMO)radars and multiple jammers in this study.First,according to the power allocation strategy,a supermodular power allocation game framework with a fixed weight(FW)vector is constructed.At the same time,a constrained optimization model for maximizing the radar utility function is established.Based on the utility function,the best power allocation strategies for the radars and jammers are obtained.The existence and uniqueness of the Nash equilibrium(NE)of the supermodular game are proved.A supermodular game algorithm with FW is proposed which converges to the NE.In addition,we use adaptive beamforming methods to suppress cross-channel interference that occurs as direct wave interferences between the radars and jammers.A supermodular game algorithm for joint power allocation and beamforming is also proposed.The algorithm can ensure the best power allocation,and also improves the interference suppression ability of the MIMO radar.Finally,the effectiveness and convergence of two algorithms are verified by numerical results.展开更多
In this Letter, a method based on the effects of imperfect oscillators in lasers is proposed to distinguish targets in continuous wave tracking lidar. This technique is based on the fact that each lidar signal source ...In this Letter, a method based on the effects of imperfect oscillators in lasers is proposed to distinguish targets in continuous wave tracking lidar. This technique is based on the fact that each lidar signal source has a specific influence on the phase noise that makes real targets from the false ones. A simulated signal is produced by complex circuits, modulators, memory, and signal oscillators. For example, a deception laser beam has an unequal and variable phase noise from a real target. Thus, the phase noise of transmitted and received signals does not have the same power levels and patterns. To consider the performance of the suggested method, the probability of detection（PD） is shown for various signal-to-noise ratios and signal-to-jammer ratios based on experimental outcomes.展开更多
Jamming attacks and unintentional radio interference are some of the most urgent threats harming the dependability of wireless communication and endangering the successful deployment of pervasive applications built on...Jamming attacks and unintentional radio interference are some of the most urgent threats harming the dependability of wireless communication and endangering the successful deployment of pervasive applications built on top of wireless networks.Unlike the traditional approaches focusing on developing jamming defense techniques without considering the location of jammers,we take a different viewpoint that the jammers'position should be identified and exploited for building a wide range of defense strategies to alleviate jamming.In this paper,we address the problem of localizing multiple jamming attackers coexisting in wireless networks by leveraging the network topology changes caused by jamming.We systematically analyze the jamming effects and develop a framework that can partition network topology into clusters and can successfully estimate the positions of multiple jammers even when their jamming areas are overlapping.Our experiments on a multi-hop network setup using MicaZ sensor nodes validate the feasibility of real-time collection of network topology changes under jamming and our extensive simulation results demonstrate that our approach is highly effective in localizing multiple attackers with or without the prior knowledge of the order that the jammers are turned on.展开更多
The widely used devices(e.g.smartphones,recorders)equipped with microphones have posed a severe threat to confidential conversations.In this paper,we design an inaudible anti-eavesdropping method:UltraJam,to reduce th...The widely used devices(e.g.smartphones,recorders)equipped with microphones have posed a severe threat to confidential conversations.In this paper,we design an inaudible anti-eavesdropping method:UltraJam,to reduce the risk of unwanted and secret recordings.UltraJam uses the ultrasonic signal to mask conversation.By leveraging the nonlinear effect of microphone circuits,the adaptive ultrasonic signal can be recorded and demodulated into low-frequency which can effectively squash the sound.Based on the characteristics of the attenuation coefficient and frequency response,we construct a number of jamming signals with different bandwidths and designed a wideband signal injection array,meanwhile adaptively adjust the power at each bandwidth signal to cover more frequency bands and increase usage scenarios.To verify the security of the microphone jamming system,we also utilize several audio recovery methods to recover the raw signal from jamming noise.The experimental results show that less than 1% of the words are recognized in the jamming recording,and even with the audio recovery method,99% of the words still cannot be recognized in the recovered jamming recording.展开更多
基金supported by the CAS Project for Young Scientists in Basic Research under Grant YSBR-035Jiangsu Provincial Key Research and Development Program under Grant BE2021013-2.
文摘In covert communications,joint jammer selection and power optimization are important to improve performance.However,existing schemes usually assume a warden with a known location and perfect Channel State Information(CSI),which is difficult to achieve in practice.To be more practical,it is important to investigate covert communications against a warden with uncertain locations and imperfect CSI,which makes it difficult for legitimate transceivers to estimate the detection probability of the warden.First,the uncertainty caused by the unknown warden location must be removed,and the Optimal Detection Position(OPTDP)of the warden is derived which can provide the best detection performance(i.e.,the worst case for a covert communication).Then,to further avoid the impractical assumption of perfect CSI,the covert throughput is maximized using only the channel distribution information.Given this OPTDP based worst case for covert communications,the jammer selection,the jamming power,the transmission power,and the transmission rate are jointly optimized to maximize the covert throughput(OPTDP-JP).To solve this coupling problem,a Heuristic algorithm based on Maximum Distance Ratio(H-MAXDR)is proposed to provide a sub-optimal solution.First,according to the analysis of the covert throughput,the node with the maximum distance ratio(i.e.,the ratio of the distances from the jammer to the receiver and that to the warden)is selected as the friendly jammer(MAXDR).Then,the optimal transmission and jamming power can be derived,followed by the optimal transmission rate obtained via the bisection method.In numerical and simulation results,it is shown that although the location of the warden is unknown,by assuming the OPTDP of the warden,the proposed OPTDP-JP can always satisfy the covertness constraint.In addition,with an uncertain warden and imperfect CSI,the covert throughput provided by OPTDP-JP is 80%higher than the existing schemes when the covertness constraint is 0.9,showing the effectiveness of OPTDP-JP.
文摘Jammers can awfully interfere with the wireless communications. The transmission and reception of wireless communication is blocked by the jammer. The intruder will place the jammer in a well topological network area and they can easily track the information. It will help them to block the signal transmission and reception. Now, the intention is to track the position of the jammer where it is fixed. The existing methods rely on the indirect measurements and the boundary node to find the jammer’s position which degrades the accuracy of the localization. To improve the efficiency, this paper proposed an efficient method namely Coincered Node Based Localization of jammers to find the position of the jammer with high level of accuracy. The proposed system uses the direct measurements, which is the jammer signal strength. The effectiveness can also be increased by using the coincered node that will stumble across the true position of the jammer. The proposed work is compared with existing methods. Then the proposed mechanism proves better to find the jammer location. The simulation results estimate that the accuracy of the localization achieves better performance than the existing schemes.
文摘This paper mainly investigates the coordinated anti-jamming channel access problems in multiuser scenarios where there exists a tracking jammer who senses the spectrum and traces the channel with maximal receiving power.To cope with the challenges brought by the tracking jammer,a multi-leader onefollower anti-jamming Stackelberg(MOAS)game is formulated,which is able to model the complex interactions between users and the tracking jammer.In the proposed game,users act as leaders,chose their channel access strategies and transmit firstly.The tracking jammer acts as the follower,whose objective is to find the optimal jamming strategy at each time slot.Besides,the existence of Stackelberg equilibriums(SEs)is proved,which means users reach Nash Equilibriums(NEs)for each jamming strategy while the jammer finds its best response jamming strategy for the current network access case.An active attraction based anti-jamming channel access(3ACA)algorithm is designed to reach SEs,where jammed users keep their channel access strategies unchanged to create access chances for other users.To enhance the fairness of the system,users will adjust their strategies and relearn after certain time slots to provide access chances for those users who sacrifice themselves to attract the tracking jammer.
基金supported by the National Natural Science Foundation of China under Grant(no.62071486,no.61771487,no.62171464).
文摘In this paper,we investigate covert communications in data collected IoT with NOMA,where the paired sensor nodes S_(m) and S_(n) transmit covert messages to a legitimate receiver(Bob)in the presence of a Warden(Willie).To confuse the detection at Willie,an extra multi-antenna friendly jammer(Jammer)has been employed to transmit artificial noise(AN)with random power.Based on the CSI of Willie is available or not at Jammer,three AN transmission schemes,including null-space artificial noise(NAN),transmit antenna selection(TAS),and zeroforcing beamforming(ZFB),are proposed.Furthermore,the closed-form expressions of expected minimum detection error probability(EMDEP)and joint connection outage probability(JCOP)are derived to measure covertness and reliability,respectively.Finally,the maximum effective covert rate(ECR)is obtained with a given covertness constraint.The numerical results show that ZFB scheme has the best maximum ECR in the case of the number of antennas satisfies N>2,and the same maximum ECR can be achieved in ZFB and NAN schemes with N=2.Moreover,TAS scheme also can improve the maximum ECR compared with the benchmark scheme(i.e.,signal-antenna jammer).In addition,a proper NOMA node pairing can further improve the maximum ECR.
基金partly supported by National Natural Science Foundation of China (No. 41504026, 61362009)Natural Science Foundation of Jiangxi (No.20152ACB21003)Foundation for Distinguished Young Talents Training Programme of Jiangxi (No.20171BCB23006)
文摘To further promote the achievable average secrecy rate for UAV-ground communications, a UAV-aided mobile jamming strategy was proposed in this paper. Specifically, an additional cooperative UAV is employed as a mobile jammer to transmit the jamming signal to help keep the source UAV closer to the ground destination, thus establishing more favorable legitimate link and enhancing the secrecy performance. We aimed to maximize the achievable secrecy rate by jointly optimizing the trajectories and transmit power of both source UAV and jammer UAV. To solve the considered non-convex optimization problem, we presented a block coordinate descent based iterative algorithm to address a sequence of approximated convex problems for the optimized parameter block by block to find a local optimal solution. Numerical results verify that the proposed algorithm can achieve significant secrecy rate gain compared to all the benchmark schemes.
文摘Objective:To evaluate the effect of long-term exposure to radiofrequency radiations emitted from mobile jammers onrat's reproductive parameters.Methods: Eighty male rats were divided into neonatal group (n=20), immature group (n=30) and mature group (n=30). Neonatal rats were randomly divided into two subgroups. Immature and mature rats were randomly divided into three subgroups. Experimental rats were fixed in the restraining tube and were exposed to radiofrequency radiations emitted from mobile jammers at a distance of 100 cm, for 30 d (7 h/d). Sham group rats were also fixed in restraining tube but without radiations. The control group was allowed to move freely without being exposed to radiation. At the end of the experiment, weight of testes, sperm quality, histological testicular sections and serum testosterone levels were evaluated.Results: Long-term exposure to radiofrequency from mobile jammers could adversely affect neonatal rat fertility, but it did not have significant effects on male mature and immature rat's reproduction parameters. However, restraint stress induced by immobilizing them for a long-period could adversely affect male mature rat's reproductive parameters, but it had no significant effect on male immature rat's reproduction parameters.Conclusion:The effects of EMF exposure to be various based on the life stage.
文摘In wireless sensor networks （WSNs）, as the shared nature of the wireless medium, jam- ming attacks can be easily launched and result in a great damage to the network. How to deal with jamming attacks has become a great concern recently. Finding the location of a jammer is important to take security actions against the jammer, and thus to restore the network communication. After a comprehensive study on the jammer localization problem, a lightweight easy-operated algorithm called triple circles localization （TCL） is proposed. The evaluation results have demonstrated that, compared with other approaches, TCL achieves the best jammer localization accuracy under variable conditions.
基金supported in part by the National Natural Science Foundation of China(No.61941105,No.61901327 and No.62101450)in part by the National Natural Science Foundation for Distinguished Young Scholar(No.61825104)+1 种基金in part by the Fundamental Research Funds for the Central Universities(JB210109)in part by the Foundation of State Key Laboratory of Integrated Services Networks of Xidian University(ISN22-03)。
文摘In this work,we investigate the covert communication in cognitive radio(CR)networks with the existence of multiple cognitive jammers(CJs).Specifically,the secondary transmitter(ST)helps the primary transmitter(PT)to relay information to primary receiver(PR),as a reward,the ST can use PT's spectrum to transmit private information against the eavesdropper(Eve)under the help of one selected cognitive jammer(CJ).Meanwhile,we propose three jammer-selection schemes,namely,link-oriented jammer selection(LJS),min-max jammer selection(MMJS)and random jammer selection(RJS).For each scheme,we analyze the average covert throughput(ACT)and covert outage probability(COP).Our simulation results show that CJ is helpful to ST's covert communication,the expected minimum detection error probability and ACT can be significantly improved with the increase of false alarm of CJ.Moreover,the LJS scheme achieves best performance in ACT and COP,followed by RJS scheme,and MMJS scheme shows the worst performance.
基金supported in part by Thailand Science Research and Innovation(TSRI)National Research Council of Thailand(NRCT)via International Research Network Program(IRN61W0006)by Khon Kaen University,Thailand。
文摘In this paper,the detection capabilities and system performance of an energy harvesting(EH)Internet of Things(Io T)architecture in the presence of an unmanned aerial vehicle(UAV)eavesdropper(UE)are investigated.The communication protocol is divided into two phases.In the first phase,a UAV relay(UR)cooperates with a friendly UAV jammer(UJ)to detect the UE,and the UR and UJ harvest energy from a power beacon(PB).In the second phase,a ground base station(GBS)sends a confidential signal to the UR using non-orthogonal multiple access(NOMA);the UR then uses its harvested energy to forward this confidential signal to IoT destinations(IDs)using the decode-and-forward(DF)technique.Simultaneously,the UJ uses its harvested energy to emit an artificial signal to combat the detected UE.A closed-form expression for the probability of detecting the UE(the detection probability,DP)is derived to analyze the detection performance.Furthermore,the intercept probability(IP)and throughput of the considered IoT architecture are determined.Accordingly,we identify the optimal altitudes for the UR and UJ to enhance the system and secrecy performance.Monte Carlo simulations are employed to verify our approach.
基金This paper was jointly supported by the National Natural Science Foundation of China，the State Major Science and Technology Special Projects，the Science Technology Innovation Foundation for Young Teachers in BUPT
文摘Abstract：Aiming at achieving better Quality of Service （QoS） provisioning in distributed wireless cooperative networks, a novel energy efficient jammer selection approach is proposed in this pa per. We employ Secrecy Capacity （SC） to charac terize the security of transmission. In order to ac curately describe the timevarying characteristic, related channels are modeled as FiniteState M ark ov Channels （FSMCs）. The remaining energy of candidate node is considered in a similar way.
文摘Localizing a jammer in an indoor environment in wireless sensor networks becomes a significant research problem due to the ease of blocking the communication between legitimate nodes. An adversary may emit radio frequency to prevent the transmission between nodes. In this paper, we propose detecting the position of the jammer indoor by using the received signal strength and Kalman filter (KF) to reduce the noise due to the multipath signal caused by obstacles in the indoor environment. We compare our work to the Linear Prediction Algorithm (LP) and Centroid Localization Algorithm (CL). We observed that the Kalman filter has better results when estimating the distance compared to other algorithms.
文摘In wireless networks, jamming attacks are easy to launch and can significantly impact the network performance. The technique which localizes the jamming attacker is useful to address this problem. Some range-based localization schemes depend on the additional hardware of wireless nodes too much, and they can not work in resource-constrained wireless networks. Solutions in range-free localization are being pursued as a cost-effective alternative to more expensive range-based approaches.In this paper, we propose a novel range-free algorithm to localize the source of the attacker. We show that our approach only relies on the positions of each jammed or no-jammed node in the network, PSO algorithm is used to get the minimum covering circle of jammed positions and the circle center is the estimated jammer location. We compare our work with some existing range-free solutions via extensive simulations in two models, which are wireless sensor network (WSN) and vehicular ad hoc network (VANET) respectively. The experimental results suggest that our proposed algorithm achieves higher accuracy than the other solutions, and the localization error goes down with larger number of recorded jammed positions. In additional, when the recorded jammed positions are distributed in a specific constrained area, the localization error goes higher, we also propose an improved PSO algorithm to deal with this issue.
基金supported by the National Natural Science Foundation of China(No.61372134)。
文摘To deal with the threat of the new generation of electronic warfare,we establish a non-cooperative countermeasure game model to analyze power allocation and interference suppression between multistatic multipleinput multiple-output(MIMO)radars and multiple jammers in this study.First,according to the power allocation strategy,a supermodular power allocation game framework with a fixed weight(FW)vector is constructed.At the same time,a constrained optimization model for maximizing the radar utility function is established.Based on the utility function,the best power allocation strategies for the radars and jammers are obtained.The existence and uniqueness of the Nash equilibrium(NE)of the supermodular game are proved.A supermodular game algorithm with FW is proposed which converges to the NE.In addition,we use adaptive beamforming methods to suppress cross-channel interference that occurs as direct wave interferences between the radars and jammers.A supermodular game algorithm for joint power allocation and beamforming is also proposed.The algorithm can ensure the best power allocation,and also improves the interference suppression ability of the MIMO radar.Finally,the effectiveness and convergence of two algorithms are verified by numerical results.
文摘In this Letter, a method based on the effects of imperfect oscillators in lasers is proposed to distinguish targets in continuous wave tracking lidar. This technique is based on the fact that each lidar signal source has a specific influence on the phase noise that makes real targets from the false ones. A simulated signal is produced by complex circuits, modulators, memory, and signal oscillators. For example, a deception laser beam has an unequal and variable phase noise from a real target. Thus, the phase noise of transmitted and received signals does not have the same power levels and patterns. To consider the performance of the suggested method, the probability of detection（PD） is shown for various signal-to-noise ratios and signal-to-jammer ratios based on experimental outcomes.
基金partially supported by the National Natural Science Foundation of China under Grant No.62172080the Natural Science Foundation of Sichuan Province under Grants 2023NSFSC0478the National Key R&D Program of China No.2022YFB3103404
文摘Jamming attacks and unintentional radio interference are some of the most urgent threats harming the dependability of wireless communication and endangering the successful deployment of pervasive applications built on top of wireless networks.Unlike the traditional approaches focusing on developing jamming defense techniques without considering the location of jammers,we take a different viewpoint that the jammers'position should be identified and exploited for building a wide range of defense strategies to alleviate jamming.In this paper,we address the problem of localizing multiple jamming attackers coexisting in wireless networks by leveraging the network topology changes caused by jamming.We systematically analyze the jamming effects and develop a framework that can partition network topology into clusters and can successfully estimate the positions of multiple jammers even when their jamming areas are overlapping.Our experiments on a multi-hop network setup using MicaZ sensor nodes validate the feasibility of real-time collection of network topology changes under jamming and our extensive simulation results demonstrate that our approach is highly effective in localizing multiple attackers with or without the prior knowledge of the order that the jammers are turned on.
基金supported by the Projects of the Natural Science Foundation of Qinghai Province(2021-ZJ-916)the National Natural Science Foundation of China(62202274).
文摘The widely used devices(e.g.smartphones,recorders)equipped with microphones have posed a severe threat to confidential conversations.In this paper,we design an inaudible anti-eavesdropping method:UltraJam,to reduce the risk of unwanted and secret recordings.UltraJam uses the ultrasonic signal to mask conversation.By leveraging the nonlinear effect of microphone circuits,the adaptive ultrasonic signal can be recorded and demodulated into low-frequency which can effectively squash the sound.Based on the characteristics of the attenuation coefficient and frequency response,we construct a number of jamming signals with different bandwidths and designed a wideband signal injection array,meanwhile adaptively adjust the power at each bandwidth signal to cover more frequency bands and increase usage scenarios.To verify the security of the microphone jamming system,we also utilize several audio recovery methods to recover the raw signal from jamming noise.The experimental results show that less than 1% of the words are recognized in the jamming recording,and even with the audio recovery method,99% of the words still cannot be recognized in the recovered jamming recording.
