As a key technology of the fifth generation （5G） wireless communications, sparse code multiple access （SCMA） system has quite high frequency utilization, but its message passing algorithm （MPA） decoder still has...As a key technology of the fifth generation （5G） wireless communications, sparse code multiple access （SCMA） system has quite high frequency utilization, but its message passing algorithm （MPA） decoder still has high time complexity. By the aid of the proposed multi-level dynamic threshold, the complexity of the MPA decoding can be greatly reduced with little error performance loss. In order to reduce a great deal of insignificant computational amounts of message update, we compare the multi-level symbols probability products with optimized multi-level thresholds step by step before they are used for message update calculation. The dynamic threshold configuration refers to the three factors： the level of input symbol probabilities, signal noise ratio （SNP.） and the number of iterations. Especially, in the joint iterative MPA-Turbo decoding procedure, since most encoded bits have good convergence, the inp^t thresholds can avoid more unnecessary computational overhead of message update and reduce the decoding time more significantly. The simulation results show that the proposed multi-level dynamic thresholds considerably reduce the decoding delay in both additive white Gaussian noise （AWGN） channel and frequency selective fading channel.展开更多
This work proposes a robust fault detection and isolation scheme for discrete-time systems subject to actuator faults,in which a bank of H_/H∞ fault detection unknown input observers(UIOs) and a zonotopic threshold a...This work proposes a robust fault detection and isolation scheme for discrete-time systems subject to actuator faults,in which a bank of H_/H∞ fault detection unknown input observers(UIOs) and a zonotopic threshold analysis strategy are considered. In observer design, finite-frequency H_ index based on the generalized Kalman-Yakubovich-Popov lemma and H∞ technique are utilized to evaluate worst-case fault sensitivity and disturbance attenuation performance, respectively. The proposed H_/H∞ fault detection observers are designed to be insensitive to the corresponding actuator fault only, but sensitive to others.Then, to overcome the weakness of predefining threshold for FDI decision-making, this work proposes a zonotopic threshold analysis method to evaluate the generated residuals. The FDI decision-making relies on the evaluation with a dynamical zonotopic threshold. Finally, numerical simulations are provided to show the feasibility of the proposed scheme.展开更多
由于传统的互补金属-氧化物-半导体(Complementary Metal Oxide Semiconductor,CMOS)神经元电路与生物学的契合性较差且电路复杂,提出了一种基于忆阻器的多端口输入的泄露-整合-激发(Leaky-Integrate-Fire,LIF)神经元电路。该电路由运...由于传统的互补金属-氧化物-半导体(Complementary Metal Oxide Semiconductor,CMOS)神经元电路与生物学的契合性较差且电路复杂,提出了一种基于忆阻器的多端口输入的泄露-整合-激发(Leaky-Integrate-Fire,LIF)神经元电路。该电路由运放、逻辑门等器件以及忆阻器构成,主要分为信号叠加模块和神经元信号产生模块。通过施加多个双尖峰脉冲信号并调节输入信号的数量和频率,模拟了生物神经元受到的不同程度刺激。研究发现施加到神经元上信号的数量和频率达到一定的值,神经元电路才会输出电压信号,这与生物体中只有受到一定程度的刺激时才会做出反应的现象是一致的。进一步,调节该电路中神经元信号产生模块的阈值电压大小,研究发现输入相同的信号,只有当电路的阈值电压较低时,神经元电路才能输出电压信号,这与生物中不同部位受到相同的刺激,神经元兴奋程度越高,越容易做出反应的现象一致。由此,该文所提出的LIF神经元电路不仅解决了传统电路输入信号单一、输入信号波形与生物信号波形差异大等问题,而且能模拟生物神经元的兴奋程度,这为人工神经网络的设计提供理论依据。展开更多
针对在负压干扰条件下,控制器局域网(Control Area Network,CAN)总线接收器存在工作异常以及传输延时较大的问题,设计了一种超宽共模输入范围的可变速率的CAN(CAN with Flexible Data rate,CAN FD)接收器。该设计通过电平移位与共射级...针对在负压干扰条件下,控制器局域网(Control Area Network,CAN)总线接收器存在工作异常以及传输延时较大的问题,设计了一种超宽共模输入范围的可变速率的CAN(CAN with Flexible Data rate,CAN FD)接收器。该设计通过电平移位与共射级相结合的方式,以减少总线信号对输入级静态工作点影响,拓展接收器的负压输入范围;采用电阻分压的方式衰减总线信号电平,以减轻输入级差分对管的耐压负担;引入低温漂电压,以产生高精度的翻转阈值;在输出级模块增添限幅晶体管,以限制接收器输出摆幅,提升传输速度。芯片采用0.18μm 60 V双极、互补、双扩散金属氧化物半导体工艺进行电路设计。仿真结果表明,在5 V电源电压条件下,设计接收器的共模输入范围为-60~60 V,阈值电压为0.71 V,迟滞门限为120 mV,温漂为0.057 mV/℃,平均传输延时小于55 ns。与相关设计相比,设计的接收器具有较宽的共模输入范围,传输延时较小,符合CAN协议规范。展开更多
基金supported by the Graduate Scientific Research and Innovation Foundation of Chongqing(CYS16023)the Foundation and Frontier Research Project of Chongqing(cstc 2016jcyj A0365)
文摘As a key technology of the fifth generation （5G） wireless communications, sparse code multiple access （SCMA） system has quite high frequency utilization, but its message passing algorithm （MPA） decoder still has high time complexity. By the aid of the proposed multi-level dynamic threshold, the complexity of the MPA decoding can be greatly reduced with little error performance loss. In order to reduce a great deal of insignificant computational amounts of message update, we compare the multi-level symbols probability products with optimized multi-level thresholds step by step before they are used for message update calculation. The dynamic threshold configuration refers to the three factors： the level of input symbol probabilities, signal noise ratio （SNP.） and the number of iterations. Especially, in the joint iterative MPA-Turbo decoding procedure, since most encoded bits have good convergence, the inp^t thresholds can avoid more unnecessary computational overhead of message update and reduce the decoding time more significantly. The simulation results show that the proposed multi-level dynamic thresholds considerably reduce the decoding delay in both additive white Gaussian noise （AWGN） channel and frequency selective fading channel.
基金partially supported by National Key R&D Program of China(2018YFB1304600)National Natural Science Foundation of China(51805021,U1813220)+1 种基金China Postdoctoral Science Foundation Grant(2018M631311)the Fundamental Research Funds for the Central Universities(XK1802-4)
文摘This work proposes a robust fault detection and isolation scheme for discrete-time systems subject to actuator faults,in which a bank of H_/H∞ fault detection unknown input observers(UIOs) and a zonotopic threshold analysis strategy are considered. In observer design, finite-frequency H_ index based on the generalized Kalman-Yakubovich-Popov lemma and H∞ technique are utilized to evaluate worst-case fault sensitivity and disturbance attenuation performance, respectively. The proposed H_/H∞ fault detection observers are designed to be insensitive to the corresponding actuator fault only, but sensitive to others.Then, to overcome the weakness of predefining threshold for FDI decision-making, this work proposes a zonotopic threshold analysis method to evaluate the generated residuals. The FDI decision-making relies on the evaluation with a dynamical zonotopic threshold. Finally, numerical simulations are provided to show the feasibility of the proposed scheme.
文摘由于传统的互补金属-氧化物-半导体(Complementary Metal Oxide Semiconductor,CMOS)神经元电路与生物学的契合性较差且电路复杂,提出了一种基于忆阻器的多端口输入的泄露-整合-激发(Leaky-Integrate-Fire,LIF)神经元电路。该电路由运放、逻辑门等器件以及忆阻器构成,主要分为信号叠加模块和神经元信号产生模块。通过施加多个双尖峰脉冲信号并调节输入信号的数量和频率,模拟了生物神经元受到的不同程度刺激。研究发现施加到神经元上信号的数量和频率达到一定的值,神经元电路才会输出电压信号,这与生物体中只有受到一定程度的刺激时才会做出反应的现象是一致的。进一步,调节该电路中神经元信号产生模块的阈值电压大小,研究发现输入相同的信号,只有当电路的阈值电压较低时,神经元电路才能输出电压信号,这与生物中不同部位受到相同的刺激,神经元兴奋程度越高,越容易做出反应的现象一致。由此,该文所提出的LIF神经元电路不仅解决了传统电路输入信号单一、输入信号波形与生物信号波形差异大等问题,而且能模拟生物神经元的兴奋程度,这为人工神经网络的设计提供理论依据。
