Beyond 3G(B3G)system,the future mobile communication system,is envisioned as a user-centric,open,and convergent information infrastructure capable of providing personalized services.It is extremely important to develo...Beyond 3G(B3G)system,the future mobile communication system,is envisioned as a user-centric,open,and convergent information infrastructure capable of providing personalized services.It is extremely important to develop service models and architectures for B3G system.A three-dimension service model is proposed.The dimensions are identified as service support scope,service capability definition,and adaptive feature elements.Then,the hierarchical service architecture for B3G is introduced.The enabling technologies for B3G service architecture are discussed in this paper,such as Virtual Home Environment(VHE),service support environment,service openness,distributed computing,intelligent technology,and profile.展开更多
IEEE 802.11 distributed coordination function （DCF） is a distributed medium access scheme based on carrier sense multiple access with collision avoidance （CSMA/CA） protocol. Many literatures have analyzed the perf...IEEE 802.11 distributed coordination function （DCF） is a distributed medium access scheme based on carrier sense multiple access with collision avoidance （CSMA/CA） protocol. Many literatures have analyzed the performance of IEEE802.11 DCF. However, such literatures either used simulation methods or built the analytical models under the assumption that the saturation condition was satisfied. To overcome such a problem, in this paper, a hi-dimensional Markovian model has been introduced to depict the DCF mechanism. The proposed model introduced an idle stage and a discrete time M/G/1 queue to deduce the channel throughput under finite load traffic. Simulation results proved the accuracy of the proposed model.展开更多
针对单一的非线性电阻元件无法模拟金属氧化物压敏电阻片的伏安特性,对IEEE模型与P-G模型进行了对比介绍,并利用ATP-EMTP仿真软件对二者使用波形为8/20μs,幅值分别为5 k A,10 k A,20 k A的雷电流进行仿真冲击。最后将仿真得到的残压与...针对单一的非线性电阻元件无法模拟金属氧化物压敏电阻片的伏安特性,对IEEE模型与P-G模型进行了对比介绍,并利用ATP-EMTP仿真软件对二者使用波形为8/20μs,幅值分别为5 k A,10 k A,20 k A的雷电流进行仿真冲击。最后将仿真得到的残压与实验数据对比。结果显示模型皆有较好的仿真结果,最大的不同就是模型中对参数值估算的复杂度不一样,P-G模型较为简单,仿真结果更精确,电路的组成更简单,实用性更强。展开更多
基金Project ofNational"863"Plan of China(No.2004AA119030)
文摘Beyond 3G(B3G)system,the future mobile communication system,is envisioned as a user-centric,open,and convergent information infrastructure capable of providing personalized services.It is extremely important to develop service models and architectures for B3G system.A three-dimension service model is proposed.The dimensions are identified as service support scope,service capability definition,and adaptive feature elements.Then,the hierarchical service architecture for B3G is introduced.The enabling technologies for B3G service architecture are discussed in this paper,such as Virtual Home Environment(VHE),service support environment,service openness,distributed computing,intelligent technology,and profile.
文摘IEEE 802.11 distributed coordination function （DCF） is a distributed medium access scheme based on carrier sense multiple access with collision avoidance （CSMA/CA） protocol. Many literatures have analyzed the performance of IEEE802.11 DCF. However, such literatures either used simulation methods or built the analytical models under the assumption that the saturation condition was satisfied. To overcome such a problem, in this paper, a hi-dimensional Markovian model has been introduced to depict the DCF mechanism. The proposed model introduced an idle stage and a discrete time M/G/1 queue to deduce the channel throughput under finite load traffic. Simulation results proved the accuracy of the proposed model.
文摘针对单一的非线性电阻元件无法模拟金属氧化物压敏电阻片的伏安特性,对IEEE模型与P-G模型进行了对比介绍,并利用ATP-EMTP仿真软件对二者使用波形为8/20μs,幅值分别为5 k A,10 k A,20 k A的雷电流进行仿真冲击。最后将仿真得到的残压与实验数据对比。结果显示模型皆有较好的仿真结果,最大的不同就是模型中对参数值估算的复杂度不一样,P-G模型较为简单,仿真结果更精确,电路的组成更简单,实用性更强。
