Cognitive Radio Network provides an opportunity to reduce the spectrum resource crisis by allowing secondary users to access the idle spectrum allocated to primary users. The precondition of spectrum sharing is to obt...Cognitive Radio Network provides an opportunity to reduce the spectrum resource crisis by allowing secondary users to access the idle spectrum allocated to primary users. The precondition of spectrum sharing is to obtain the Spectrum Availability Information(SAI). Energy detection is a typical technology to get SAI. With the mobility of primary users, the energy received by secondary users varies greatly with the distance from the target primary users. Most of the existing energy detection algorithms that use fixed thresholds are not suitable. We propose a Dynamic Matching-Based Spectrum Detection(DMBSD) scheme which can detect sensing data, reduce the impact of malicious data and make final sensing results more accurate with dynamic threshold setting and data matching. Simulation results show that the proposed scheme can detect tempered data, and increase detection probability by decreasing false alarm probability and missed detection probability.展开更多
In this work,we have searched for quasi-periodic oscillations(QPOs)in the 15 GHz light curve of the FSRQ PKS J0805-0111 monitored by the Owens Valley Radio Observatory(OVRO)40 m telescope during the period from 2008 J...In this work,we have searched for quasi-periodic oscillations(QPOs)in the 15 GHz light curve of the FSRQ PKS J0805-0111 monitored by the Owens Valley Radio Observatory(OVRO)40 m telescope during the period from 2008 January 9 to 2019 May 9,using the weighted wavelet Z-transform(WWZ)and the Lomb-Scargle Periodogram(LSP)techniques.This is the first time to search for a periodic radio signal in the FSRQ PKS J0805-0111 by these two methods.Both methods consistently reveal a repeating signal with a periodicity of 3.38±0.8 yr(>99.7%confidence level).In order to determine the significance of the periods,the false alarm probability method was applied,and a large number of Monte Carlo simulations were performed.As possible explanations,we discuss a number of scenarios including the thermal instability of thin disks scenario,the spiral jet scenario and the binary supermassive black hole scenario.We expect that the binary black hole scenario,where the QPO is caused by the precession of binary black holes,is the most likely explanation.FSRQ PKS J0805-0111 thus could be a good binary black hole candidate.In the binary black hole scenario,the distance between the primary black hole and the secondary black hole is about 1.71×10^(16) cm.展开更多
Identifying speed,tag average response times and reliability are the most important capabilities in passive RFID(radio frequency identification) system.QT(query tree) is a famous algorithm for lowest-cost RFID tags,bu...Identifying speed,tag average response times and reliability are the most important capabilities in passive RFID(radio frequency identification) system.QT(query tree) is a famous algorithm for lowest-cost RFID tags,but its shortcoming is high searching delay and high tag average response times.A prefix subsection matching binary(PSMB) algorithm based on QTalgorithm is proposed.The key idea of PSMB anti-collision algorithm is that,during searching phase,a given reader uses the particular tags ID,which has been searched out formerly,to shorten searching delay and depress tag average response times.The idea of PSMB algorithm can be described as follows.Usually,tag ID is composed of several subsections which have different meanings.Based on the tags ID searched out formerly,a given reader builds a prefix database.In subsequent searching phase,the reader uses its prefix database to deduce searching space of tag ID.Simulation results show that identification delay of PSMB algorithm is about 1/3 of QTalgorithm,tag average response times is about 1/4 of QTalgorithm,and system throughput rate is treble QTalgorithm.展开更多
In this paper, an attempt has been made to produce a recipient system of wireless charge for a simple hearing aid so that electrical signal would be generated through detecting and receiving radio frequency waves (RF)...In this paper, an attempt has been made to produce a recipient system of wireless charge for a simple hearing aid so that electrical signal would be generated through detecting and receiving radio frequency waves (RF). The purpose of this design is to receive wireless charge for hearing aids and basically for any electronic device which is not required to a high energy for being setup. In this study, it has been demonstrated that as the amount of radio receiving energy increases, distance of receiver from antenna should be decreased;otherwise, either maximum amount of the receiving energy, or signal power density of the transmitter should be increased. Since it is impossible to be performed, it is decided to set up an energy receiving system constructed by rectenna and charge Circuit and to adjust their parameters to provide energy requirements for a device with low-power consumption. In this paper, different components of an energy receiving system from radio frequency band have been mentioned and a diagram block has been suggested. Subsequently, input impedance of designed antenna has been adjusted by provided relations. This impedance should be adjusted with the total impedance of regarded hearing aid Circuit by which the highest amount of received signal power is transferred to the battery of hearing aids. Received signal is converted to a dc voltage by rectifier diode. Finally, by applying a voltage regulator which has been designed using a common-collector amplifier not only the output voltage is kept constant, but the power is also strengthened. The battery of the hearing aids will be charged using the obtained power and voltage.展开更多
In this paper,we propose a sensing scheme based on energy detection,matched filter and cyclic prefix.Both Equal Gain Combining(EGC)and optimal combination of the aforementioned detectors are investigated in cooperativ...In this paper,we propose a sensing scheme based on energy detection,matched filter and cyclic prefix.Both Equal Gain Combining(EGC)and optimal combination of the aforementioned detectors are investigated in cooperative and non-cooperative spectrum sensing scenarios.In packet transmission systems such as OFDM(Orthogonal Frequency Division Multiple access)systems,the proposed scheme takes advantage of utilizing more samples than individual detectors,i.e.,cyclic prefix,training or pilot samples,and data payload samples.The proposed combine-sensing scheme offers higher detection probability and lower false alarm probability,as compared with the performance of individual detectors over the same frame duration.Simulation results are congruent with the theoretical curves and confirm the validity of our derivations.展开更多
基金supported by the National Natural Science Foundation of China (No.61602358)the Key Program of NSFC-Tongyong Union Foundation under Grant U1636209the Fundamental Research Funds for the Central Universities (No.XJS17078)
文摘Cognitive Radio Network provides an opportunity to reduce the spectrum resource crisis by allowing secondary users to access the idle spectrum allocated to primary users. The precondition of spectrum sharing is to obtain the Spectrum Availability Information(SAI). Energy detection is a typical technology to get SAI. With the mobility of primary users, the energy received by secondary users varies greatly with the distance from the target primary users. Most of the existing energy detection algorithms that use fixed thresholds are not suitable. We propose a Dynamic Matching-Based Spectrum Detection(DMBSD) scheme which can detect sensing data, reduce the impact of malicious data and make final sensing results more accurate with dynamic threshold setting and data matching. Simulation results show that the proposed scheme can detect tempered data, and increase detection probability by decreasing false alarm probability and missed detection probability.
基金supported by the National Natural Science Foundation of China(Grant No.11663009)the High-Energy Astrophysics Science and Technology Innovation Team of Yunnan Higher School+1 种基金the OVRO40-m monitoring program(Fan&Wu 2018)which is supported in part by NASA grants NNX08AW31GNNX11A043G and NNX14AQ89G,and NSF grants AST-0808050 and AST-1109911。
文摘In this work,we have searched for quasi-periodic oscillations(QPOs)in the 15 GHz light curve of the FSRQ PKS J0805-0111 monitored by the Owens Valley Radio Observatory(OVRO)40 m telescope during the period from 2008 January 9 to 2019 May 9,using the weighted wavelet Z-transform(WWZ)and the Lomb-Scargle Periodogram(LSP)techniques.This is the first time to search for a periodic radio signal in the FSRQ PKS J0805-0111 by these two methods.Both methods consistently reveal a repeating signal with a periodicity of 3.38±0.8 yr(>99.7%confidence level).In order to determine the significance of the periods,the false alarm probability method was applied,and a large number of Monte Carlo simulations were performed.As possible explanations,we discuss a number of scenarios including the thermal instability of thin disks scenario,the spiral jet scenario and the binary supermassive black hole scenario.We expect that the binary black hole scenario,where the QPO is caused by the precession of binary black holes,is the most likely explanation.FSRQ PKS J0805-0111 thus could be a good binary black hole candidate.In the binary black hole scenario,the distance between the primary black hole and the secondary black hole is about 1.71×10^(16) cm.
基金Sponsored by the National Natural Science Foundation of China(60372042)
文摘Identifying speed,tag average response times and reliability are the most important capabilities in passive RFID(radio frequency identification) system.QT(query tree) is a famous algorithm for lowest-cost RFID tags,but its shortcoming is high searching delay and high tag average response times.A prefix subsection matching binary(PSMB) algorithm based on QTalgorithm is proposed.The key idea of PSMB anti-collision algorithm is that,during searching phase,a given reader uses the particular tags ID,which has been searched out formerly,to shorten searching delay and depress tag average response times.The idea of PSMB algorithm can be described as follows.Usually,tag ID is composed of several subsections which have different meanings.Based on the tags ID searched out formerly,a given reader builds a prefix database.In subsequent searching phase,the reader uses its prefix database to deduce searching space of tag ID.Simulation results show that identification delay of PSMB algorithm is about 1/3 of QTalgorithm,tag average response times is about 1/4 of QTalgorithm,and system throughput rate is treble QTalgorithm.
文摘In this paper, an attempt has been made to produce a recipient system of wireless charge for a simple hearing aid so that electrical signal would be generated through detecting and receiving radio frequency waves (RF). The purpose of this design is to receive wireless charge for hearing aids and basically for any electronic device which is not required to a high energy for being setup. In this study, it has been demonstrated that as the amount of radio receiving energy increases, distance of receiver from antenna should be decreased;otherwise, either maximum amount of the receiving energy, or signal power density of the transmitter should be increased. Since it is impossible to be performed, it is decided to set up an energy receiving system constructed by rectenna and charge Circuit and to adjust their parameters to provide energy requirements for a device with low-power consumption. In this paper, different components of an energy receiving system from radio frequency band have been mentioned and a diagram block has been suggested. Subsequently, input impedance of designed antenna has been adjusted by provided relations. This impedance should be adjusted with the total impedance of regarded hearing aid Circuit by which the highest amount of received signal power is transferred to the battery of hearing aids. Received signal is converted to a dc voltage by rectifier diode. Finally, by applying a voltage regulator which has been designed using a common-collector amplifier not only the output voltage is kept constant, but the power is also strengthened. The battery of the hearing aids will be charged using the obtained power and voltage.
文摘In this paper,we propose a sensing scheme based on energy detection,matched filter and cyclic prefix.Both Equal Gain Combining(EGC)and optimal combination of the aforementioned detectors are investigated in cooperative and non-cooperative spectrum sensing scenarios.In packet transmission systems such as OFDM(Orthogonal Frequency Division Multiple access)systems,the proposed scheme takes advantage of utilizing more samples than individual detectors,i.e.,cyclic prefix,training or pilot samples,and data payload samples.The proposed combine-sensing scheme offers higher detection probability and lower false alarm probability,as compared with the performance of individual detectors over the same frame duration.Simulation results are congruent with the theoretical curves and confirm the validity of our derivations.
文摘射频电路优化设计是保证射频通信系统高可靠、低功耗、远距离数据传输的重要手段。针对商用CC1101射频电路传输距离短和丢包率高的问题,通过高频电磁仿真软件ADS(Advanced Design System)对CC1101射频电路中阻抗变换器、滤波器和射频全链路进行仿真优化,根据仿真结果调整元器件,并测试了改版CC1101射频电路的传输距离和数据包接收率。结果表明,优化后射频电路阻抗(115+j42Ω)更接近目标差分阻抗(116+j41Ω),回波损耗提高11 d B,插入损耗减少0.6 d B,稳定传输距离提升30 m,在传输距离为60 m时数据接收率提高33.6%。
