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
目的:探讨超低频重复经颅磁刺激(repetitive transcranial magnetic stimulation,rTMS)治疗老年人急性脑梗死吞咽障碍的临床疗效及对生存质量的影响。方法:将60例老年急性脑梗死吞咽障碍患者随机分为rTMS组和对照组,每组30例,两组均进...目的:探讨超低频重复经颅磁刺激(repetitive transcranial magnetic stimulation,rTMS)治疗老年人急性脑梗死吞咽障碍的临床疗效及对生存质量的影响。方法:将60例老年急性脑梗死吞咽障碍患者随机分为rTMS组和对照组,每组30例,两组均进行常规药物治疗和吞咽功能训练,rTMS组另加超低频(10 MHz)重复经颅磁刺激治疗,疗程14 d。观察比较两组治疗前后国立卫生研究院卒中量表(national institutes of health stroke scale,NIHSS)评分、日常生活活动(activity of daily living,ADL)能力评定量表评分、神经元特异性烯醇化酶(neuron-specific enolase,NSE)血清水平、洼田饮水试验、藤岛一郎吞咽障碍量表评分、吞咽障碍特异性生活质量量表(swallowing related quality of life,SWAL-QOL)及中文版生活质量量表简表(medical outcomes study short form 36 scale,SF-36)评分变化情况。采用洼田饮水实验评估患者的临床疗效。结果:rTMS组治疗后临床有效率较对照组明显提升(P<0.05),NIHSS评分、血清NSE水平较对照组显著降低(P<0.05),ADL评分、藤岛一郎吞咽障碍评分、SWAL-QOL评分、SF-36各维度评分及总评分较对照组显著上升(P<0.05)。治疗后SF-36总评分及SWAL-QOL评分与NSE血清水平、NIHSS量表评分呈负相关,与ADL评分、藤岛一郎吞咽障碍评分呈正相关。结论:超低频rTMS治疗可降低血清NSE水平、有效改善老年人急性脑梗死吞咽障碍以及显著提高老年患者的生存质量。展开更多
A novel low-complexity weighted symbol-flipping algorithm with flipping patterns to decode nonbinary low-density parity-check codes is proposed. The proposed decoding procedure updates the hard-decision received symbo...A novel low-complexity weighted symbol-flipping algorithm with flipping patterns to decode nonbinary low-density parity-check codes is proposed. The proposed decoding procedure updates the hard-decision received symbol vector iteratively in search of a valid codeword in the symbol vector space. Only one symbol is flipped in each iteration, and symbol flipping function, which is employed as the symbol flipping metric, combines the number of failed checks and the reliabilities of the received bits and calculated symbols. A scheme to avoid infinite loops and select one symbol to flip in high order Galois field search is also proposed. The design of flipping pattern＇s order and depth, which is dependent of the computational requirement and error performance, is also proposed and exemplified. Simulation results show that the algorithm achieves an appealing tradeoff between performance and computational requirement over relatively low Galois field for short to medium code length.展开更多
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。
文摘目的:探讨超低频重复经颅磁刺激(repetitive transcranial magnetic stimulation,rTMS)治疗老年人急性脑梗死吞咽障碍的临床疗效及对生存质量的影响。方法:将60例老年急性脑梗死吞咽障碍患者随机分为rTMS组和对照组,每组30例,两组均进行常规药物治疗和吞咽功能训练,rTMS组另加超低频(10 MHz)重复经颅磁刺激治疗,疗程14 d。观察比较两组治疗前后国立卫生研究院卒中量表(national institutes of health stroke scale,NIHSS)评分、日常生活活动(activity of daily living,ADL)能力评定量表评分、神经元特异性烯醇化酶(neuron-specific enolase,NSE)血清水平、洼田饮水试验、藤岛一郎吞咽障碍量表评分、吞咽障碍特异性生活质量量表(swallowing related quality of life,SWAL-QOL)及中文版生活质量量表简表(medical outcomes study short form 36 scale,SF-36)评分变化情况。采用洼田饮水实验评估患者的临床疗效。结果:rTMS组治疗后临床有效率较对照组明显提升(P<0.05),NIHSS评分、血清NSE水平较对照组显著降低(P<0.05),ADL评分、藤岛一郎吞咽障碍评分、SWAL-QOL评分、SF-36各维度评分及总评分较对照组显著上升(P<0.05)。治疗后SF-36总评分及SWAL-QOL评分与NSE血清水平、NIHSS量表评分呈负相关,与ADL评分、藤岛一郎吞咽障碍评分呈正相关。结论:超低频rTMS治疗可降低血清NSE水平、有效改善老年人急性脑梗死吞咽障碍以及显著提高老年患者的生存质量。
文摘A novel low-complexity weighted symbol-flipping algorithm with flipping patterns to decode nonbinary low-density parity-check codes is proposed. The proposed decoding procedure updates the hard-decision received symbol vector iteratively in search of a valid codeword in the symbol vector space. Only one symbol is flipped in each iteration, and symbol flipping function, which is employed as the symbol flipping metric, combines the number of failed checks and the reliabilities of the received bits and calculated symbols. A scheme to avoid infinite loops and select one symbol to flip in high order Galois field search is also proposed. The design of flipping pattern＇s order and depth, which is dependent of the computational requirement and error performance, is also proposed and exemplified. Simulation results show that the algorithm achieves an appealing tradeoff between performance and computational requirement over relatively low Galois field for short to medium code length.
