Considering that the collision caused by hidden terminal is particularly serious due to the narrow beams of optical de- vices, the multi-packet reception （MPR） is introduced to mitigate the collisions for IEEE 802.1...Considering that the collision caused by hidden terminal is particularly serious due to the narrow beams of optical de- vices, the multi-packet reception （MPR） is introduced to mitigate the collisions for IEEE 802.15.7 visible light com- munication （VLC） system. To explore the impact of MPR on system performance and investigate the interaction be- tween physical （PHY） layer and media access control （MAC） layer, a three dimensional （3D） integrated PHY-MAC analytical model of carrier sense muttiple access/collision avoidance （CSMA/CA） is established based on Markov chain theory for VLC system, in which MPR is implemented through the use of orthogonal code sequence. Throughput is derived to evaluate the performance of VLC system with MPR capability under imperfect optical channel. The re- sults can be used for the performance optimization of a VLC system with MPR capability.展开更多
电力线和无线混合通信可以优势互补提升电力物联网室内覆盖的综合性能。针对无线接入和电力线中继的混合通信场景,文章提出一种适用于两跳混合中继的通用MAC层算法。综合考虑物理层信道参数和MAC层的载波侦听多路访问(carrier sense mul...电力线和无线混合通信可以优势互补提升电力物联网室内覆盖的综合性能。针对无线接入和电力线中继的混合通信场景,文章提出一种适用于两跳混合中继的通用MAC层算法。综合考虑物理层信道参数和MAC层的载波侦听多路访问(carrier sense multiple access,CSMA)退避流程,建立了该MAC层算法的跨层性能分析模型,推导了两跳传输系统归一化吞吐量以及系统时延等性能;最后仿真验证了算法有效性和模型准确性,分析了物理层和MAC层关键参数影响系统性能的机理。与Basic-RTS/CTS算法相比,所提算法可有效提升系统吞吐量和时延性能。展开更多
Frame resolution and physical layer (PHY) protocol type detection are the basis of research and development of intrusion prevention systems for IEEE 802.11 wireless network. Aiming at the problems which cannot be solv...Frame resolution and physical layer (PHY) protocol type detection are the basis of research and development of intrusion prevention systems for IEEE 802.11 wireless network. Aiming at the problems which cannot be solved by the specifications export, this paper proposed a MAC frame analytical method and a PHY protocol type detection algorithm based on parsing the IEEE 802.11packets captured by the library Libpcap. The packet structure and the length of the frame preamble (18 or 26 bytes) are presented. Then the methods of transforming byte-order and resolving sub-fields are given. A detection algorithm of PHY protocol type is proposed based on the experiments and examples are given to verify these methods. This work can be a reference for the R & D related to link layer frame analysis.展开更多
介绍了美国国家半导体公司的PHY芯片DP83848C的功能特性;给出了在RMII(Reduced Medium Independent Interface,精简的介质无关接口)模式下的硬件电路及软件设计,以及在PCB布局布线过程中的注意事项。该设计为嵌入式系统中以太网底层的...介绍了美国国家半导体公司的PHY芯片DP83848C的功能特性;给出了在RMII(Reduced Medium Independent Interface,精简的介质无关接口)模式下的硬件电路及软件设计,以及在PCB布局布线过程中的注意事项。该设计为嵌入式系统中以太网底层的软硬件设计提供了参考,也为TCP/IP协议在嵌入式系统上的实现提供了硬件平台。展开更多
基金supported by the National Natural Science Foundation of China(No.61071074)Jilin Provincial Science&Technology Department of China(No.20130413052GH)
文摘Considering that the collision caused by hidden terminal is particularly serious due to the narrow beams of optical de- vices, the multi-packet reception （MPR） is introduced to mitigate the collisions for IEEE 802.15.7 visible light com- munication （VLC） system. To explore the impact of MPR on system performance and investigate the interaction be- tween physical （PHY） layer and media access control （MAC） layer, a three dimensional （3D） integrated PHY-MAC analytical model of carrier sense muttiple access/collision avoidance （CSMA/CA） is established based on Markov chain theory for VLC system, in which MPR is implemented through the use of orthogonal code sequence. Throughput is derived to evaluate the performance of VLC system with MPR capability under imperfect optical channel. The re- sults can be used for the performance optimization of a VLC system with MPR capability.
文摘电力线和无线混合通信可以优势互补提升电力物联网室内覆盖的综合性能。针对无线接入和电力线中继的混合通信场景,文章提出一种适用于两跳混合中继的通用MAC层算法。综合考虑物理层信道参数和MAC层的载波侦听多路访问(carrier sense multiple access,CSMA)退避流程,建立了该MAC层算法的跨层性能分析模型,推导了两跳传输系统归一化吞吐量以及系统时延等性能;最后仿真验证了算法有效性和模型准确性,分析了物理层和MAC层关键参数影响系统性能的机理。与Basic-RTS/CTS算法相比,所提算法可有效提升系统吞吐量和时延性能。
文摘Frame resolution and physical layer (PHY) protocol type detection are the basis of research and development of intrusion prevention systems for IEEE 802.11 wireless network. Aiming at the problems which cannot be solved by the specifications export, this paper proposed a MAC frame analytical method and a PHY protocol type detection algorithm based on parsing the IEEE 802.11packets captured by the library Libpcap. The packet structure and the length of the frame preamble (18 or 26 bytes) are presented. Then the methods of transforming byte-order and resolving sub-fields are given. A detection algorithm of PHY protocol type is proposed based on the experiments and examples are given to verify these methods. This work can be a reference for the R & D related to link layer frame analysis.
文摘介绍了美国国家半导体公司的PHY芯片DP83848C的功能特性;给出了在RMII(Reduced Medium Independent Interface,精简的介质无关接口)模式下的硬件电路及软件设计,以及在PCB布局布线过程中的注意事项。该设计为嵌入式系统中以太网底层的软硬件设计提供了参考,也为TCP/IP协议在嵌入式系统上的实现提供了硬件平台。
