针对水声通信带宽低、时延长、误码率高、多普勒效应显著等特征,分析了传统可靠传输机制在水下传感器网络应用的局限性,提出了基于数字喷泉码-优化Raptor码的水下传感器网络可靠传输机制。采用反馈控制对Raptor码内码的鲁棒孤子分布和...针对水声通信带宽低、时延长、误码率高、多普勒效应显著等特征,分析了传统可靠传输机制在水下传感器网络应用的局限性,提出了基于数字喷泉码-优化Raptor码的水下传感器网络可靠传输机制。采用反馈控制对Raptor码内码的鲁棒孤子分布和多项式描述的Shokrollahi度分布进行优化设计,降低了编码包平均度。进一步对Raptor码的内码—弱化的LT码(Luby transform codes)的编解码进行优化,实现了快速的编解码。基于优化Raptor码的可靠传输机制采用反馈控制,动态评估信道删除概率,从而提高编解码和通信效率。通过Aqua-Sim仿真工具对提出的可靠传输机制与基于编码的多跳协同可靠数据传输(coding based multi-hop coordinated reliable data transfer,CCRDT)机制进行仿真对比。结果表明,所提出的可靠传输机制明显降低了传输开销,提高了数据吞吐量。展开更多
Following a series of surveys since 2003, a full-seasonal raptor count was undertaken at Baiwangshan, a mountain in the vicinity of Beijing, from 6 March to 22 May 2009, when 3802 individual birds of 23 species were r...Following a series of surveys since 2003, a full-seasonal raptor count was undertaken at Baiwangshan, a mountain in the vicinity of Beijing, from 6 March to 22 May 2009, when 3802 individual birds of 23 species were recorded. Four species, i.e., Oriental Honey Buzzard(Pernis ptilorhynchus), Common Buzzard(Buteo buteo), Eurasian Sparrow Hawk(Accipiter nisus) and Gray-faced Buzzard(Butastur indicus) together accounted for up 90% of the total and P. ptilorhynchus alone for 70%. Raptor passage of such magnitude and diversity at an inland site in China was unheard of up to then. As well, 113 other migrants were recorded at the site during this period, including 24 water birds, 74 passerines and 15 others(cuckoos, owls and other migrants).展开更多
文摘针对水声通信带宽低、时延长、误码率高、多普勒效应显著等特征,分析了传统可靠传输机制在水下传感器网络应用的局限性,提出了基于数字喷泉码-优化Raptor码的水下传感器网络可靠传输机制。采用反馈控制对Raptor码内码的鲁棒孤子分布和多项式描述的Shokrollahi度分布进行优化设计,降低了编码包平均度。进一步对Raptor码的内码—弱化的LT码(Luby transform codes)的编解码进行优化,实现了快速的编解码。基于优化Raptor码的可靠传输机制采用反馈控制,动态评估信道删除概率,从而提高编解码和通信效率。通过Aqua-Sim仿真工具对提出的可靠传输机制与基于编码的多跳协同可靠数据传输(coding based multi-hop coordinated reliable data transfer,CCRDT)机制进行仿真对比。结果表明,所提出的可靠传输机制明显降低了传输开销,提高了数据吞吐量。
文摘Following a series of surveys since 2003, a full-seasonal raptor count was undertaken at Baiwangshan, a mountain in the vicinity of Beijing, from 6 March to 22 May 2009, when 3802 individual birds of 23 species were recorded. Four species, i.e., Oriental Honey Buzzard(Pernis ptilorhynchus), Common Buzzard(Buteo buteo), Eurasian Sparrow Hawk(Accipiter nisus) and Gray-faced Buzzard(Butastur indicus) together accounted for up 90% of the total and P. ptilorhynchus alone for 70%. Raptor passage of such magnitude and diversity at an inland site in China was unheard of up to then. As well, 113 other migrants were recorded at the site during this period, including 24 water birds, 74 passerines and 15 others(cuckoos, owls and other migrants).
