This paper proposes a reliability evaluation model for a multi-dimensional network system,which has potential to be applied to the internet of things or other practical networks.A multi-dimensional network system with...This paper proposes a reliability evaluation model for a multi-dimensional network system,which has potential to be applied to the internet of things or other practical networks.A multi-dimensional network system with one source element and multiple sink elements is considered first.Each element can con-nect with other elements within a stochastic connection ranges.The system is regarded as successful as long as the source ele-ment remains connected with all sink elements.An importance measure is proposed to evaluate the performance of non-source elements.Furthermore,to calculate the system reliability and the element importance measure,a multi-valued decision diagram based approach is structured and its complexity is analyzed.Finally,a numerical example about the signal transfer station system is illustrated to analyze the system reliability and the ele-ment importance measure.展开更多
Because the existing range-Doppler algorithm in inverse synthetic aperture sonar (ISAS) is based on target model of uniform motion, it may be invalidated for maneuvering targets due to the time-varying changes of both...Because the existing range-Doppler algorithm in inverse synthetic aperture sonar (ISAS) is based on target model of uniform motion, it may be invalidated for maneuvering targets due to the time-varying changes of both individual scatter′s Doppler and imaging projection plane. To resolve the problem, a new range-instantaneous Doppler imaging method is proposed for imaging maneuvering targets based on time-frequency analysis. The proposed approach is verified using real underwater acoustic data.展开更多
LoRa(Long Range radio)系统在当前不断发展的低功率广域网(LPWAN)中处于相对领先地位。它的MAC层采用的是基于ALOHA的接入协议。该接入机制虽然简单易实现,但同时也容易加剧冲突和碰撞的发生,降低整个系统的通信性能。因此,需要研究多...LoRa(Long Range radio)系统在当前不断发展的低功率广域网(LPWAN)中处于相对领先地位。它的MAC层采用的是基于ALOHA的接入协议。该接入机制虽然简单易实现,但同时也容易加剧冲突和碰撞的发生,降低整个系统的通信性能。因此,需要研究多个终端同时占用信道资源时的相互干扰情况,而LoRa信号的扩频因子(SF)将决定信号的通信覆盖范围。因此,分析了干扰信号的SF与发送信号的SF相同以及不同时,干扰信号对发送信号解调性能的影响。实验结果表明,相同SF信号间的干扰影响相对较大,而干扰信号使用的SF与发送信号不同时,干扰的影响相对较小。通过理论分析,获得了接收端正确解调时所要求的信干比(SIR)。可见,不同SF的LoRa信号可看作伪正交。展开更多
基金supported by the National Natural Science Foundation of China(72101025,72271049),the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities,FRF-IDRY-24-024)the Hebei Natural Science Foundation(F2023501011)+1 种基金the Fundamental Research Funds for the Central Universities(FRF-TP-20-073A1)the R&D Program of Beijing Municipal Education Commission(KM202411232015).
文摘This paper proposes a reliability evaluation model for a multi-dimensional network system,which has potential to be applied to the internet of things or other practical networks.A multi-dimensional network system with one source element and multiple sink elements is considered first.Each element can con-nect with other elements within a stochastic connection ranges.The system is regarded as successful as long as the source ele-ment remains connected with all sink elements.An importance measure is proposed to evaluate the performance of non-source elements.Furthermore,to calculate the system reliability and the element importance measure,a multi-valued decision diagram based approach is structured and its complexity is analyzed.Finally,a numerical example about the signal transfer station system is illustrated to analyze the system reliability and the ele-ment importance measure.
文摘Because the existing range-Doppler algorithm in inverse synthetic aperture sonar (ISAS) is based on target model of uniform motion, it may be invalidated for maneuvering targets due to the time-varying changes of both individual scatter′s Doppler and imaging projection plane. To resolve the problem, a new range-instantaneous Doppler imaging method is proposed for imaging maneuvering targets based on time-frequency analysis. The proposed approach is verified using real underwater acoustic data.
文摘LoRa(Long Range radio)系统在当前不断发展的低功率广域网(LPWAN)中处于相对领先地位。它的MAC层采用的是基于ALOHA的接入协议。该接入机制虽然简单易实现,但同时也容易加剧冲突和碰撞的发生,降低整个系统的通信性能。因此,需要研究多个终端同时占用信道资源时的相互干扰情况,而LoRa信号的扩频因子(SF)将决定信号的通信覆盖范围。因此,分析了干扰信号的SF与发送信号的SF相同以及不同时,干扰信号对发送信号解调性能的影响。实验结果表明,相同SF信号间的干扰影响相对较大,而干扰信号使用的SF与发送信号不同时,干扰的影响相对较小。通过理论分析,获得了接收端正确解调时所要求的信干比(SIR)。可见,不同SF的LoRa信号可看作伪正交。
