针对PTP(precise time protocol)协议在应用层获取软件时间戳导致时钟同步精度下降的问题,提出一种基于MAC(media access control)层获取硬件时间戳的PTP同步优化方案。设计了以STM32F407微处理器为核心的PTP时钟应用平台,在MAC层实现...针对PTP(precise time protocol)协议在应用层获取软件时间戳导致时钟同步精度下降的问题,提出一种基于MAC(media access control)层获取硬件时间戳的PTP同步优化方案。设计了以STM32F407微处理器为核心的PTP时钟应用平台,在MAC层实现了硬件时间戳获取,避免了由于协议栈软件处理延时产生的不确定性;针对PTP时钟晶振老化导致的时间同步偏差及网络延迟抖动问题,采用迭代方法优化了本地时钟频率调节算法,提高了频率校正精度。经实际测试,主从时钟偏差的RMS(root mean square)优于20 ns,提升了时钟同步精度。展开更多
Many energy efficiency asynchronous duty-cycle MAC(media access control) protocols have been proposed in recent years.However,in these protocols,wireless sensor nodes almost choose their wakeup time randomly during th...Many energy efficiency asynchronous duty-cycle MAC(media access control) protocols have been proposed in recent years.However,in these protocols,wireless sensor nodes almost choose their wakeup time randomly during the operational cycle,which results in the packet delivery latency increased significantly on the multiple hops path.To reduce the packet delivery latency on multi-hop path and energy waste of the sender's idle listening,a new low latency routing-enhanced asynchronous duty-cycle MAC protocol was presented,called REA-MAC.In REA-MAC,each sensor node decided when it waked up to send the beacon based on cross-layer routing information.Furthermore,the sender adaptively waked up based on the relationship between the transmission request time and the wakeup time of its next hop node.The simulation results show that REA-MAC reduces delivery latency by 60% compared to RI-MAC and reduces 8.77% power consumption on average.Under heavy traffic,REA-MAC's throughput is 1.48 times of RI-MAC's.展开更多
针对现有能够应用于太赫兹超高速无线网络的能量和频谱感知的媒介接入控制(energy and spectrum-aware media access control,ES-MAC)及IEEE802.15.3c协议存在的时隙申请量未及时更新、超帧结构不合理及分配时隙时未合并同一对节点之间...针对现有能够应用于太赫兹超高速无线网络的能量和频谱感知的媒介接入控制(energy and spectrum-aware media access control,ES-MAC)及IEEE802.15.3c协议存在的时隙申请量未及时更新、超帧结构不合理及分配时隙时未合并同一对节点之间的时隙请求等问题,提出了一种高吞吐量低时延MAC(high throughput low delay MAC,HLMAC)协议。通过设计一种新的超帧结构,使节点及时得到时隙分配信息,大大降低数据接入时延;通过更新时隙请求量和合并同一对节点的时隙请求,增加了数据发送量,提高了网络吞吐量。理论分析表明了HLMAC协议的有效性,仿真结果显示它比ES-MAC协议增加了65.7%的网络吞吐量,同时降低了30%的接入时延。展开更多
文摘针对PTP(precise time protocol)协议在应用层获取软件时间戳导致时钟同步精度下降的问题,提出一种基于MAC(media access control)层获取硬件时间戳的PTP同步优化方案。设计了以STM32F407微处理器为核心的PTP时钟应用平台,在MAC层实现了硬件时间戳获取,避免了由于协议栈软件处理延时产生的不确定性;针对PTP时钟晶振老化导致的时间同步偏差及网络延迟抖动问题,采用迭代方法优化了本地时钟频率调节算法,提高了频率校正精度。经实际测试,主从时钟偏差的RMS(root mean square)优于20 ns,提升了时钟同步精度。
基金Projects(61103011,61170261) supported by the National Natural Science Foundation of China
文摘Many energy efficiency asynchronous duty-cycle MAC(media access control) protocols have been proposed in recent years.However,in these protocols,wireless sensor nodes almost choose their wakeup time randomly during the operational cycle,which results in the packet delivery latency increased significantly on the multiple hops path.To reduce the packet delivery latency on multi-hop path and energy waste of the sender's idle listening,a new low latency routing-enhanced asynchronous duty-cycle MAC protocol was presented,called REA-MAC.In REA-MAC,each sensor node decided when it waked up to send the beacon based on cross-layer routing information.Furthermore,the sender adaptively waked up based on the relationship between the transmission request time and the wakeup time of its next hop node.The simulation results show that REA-MAC reduces delivery latency by 60% compared to RI-MAC and reduces 8.77% power consumption on average.Under heavy traffic,REA-MAC's throughput is 1.48 times of RI-MAC's.
文摘针对现有能够应用于太赫兹超高速无线网络的能量和频谱感知的媒介接入控制(energy and spectrum-aware media access control,ES-MAC)及IEEE802.15.3c协议存在的时隙申请量未及时更新、超帧结构不合理及分配时隙时未合并同一对节点之间的时隙请求等问题,提出了一种高吞吐量低时延MAC(high throughput low delay MAC,HLMAC)协议。通过设计一种新的超帧结构,使节点及时得到时隙分配信息,大大降低数据接入时延;通过更新时隙请求量和合并同一对节点的时隙请求,增加了数据发送量,提高了网络吞吐量。理论分析表明了HLMAC协议的有效性,仿真结果显示它比ES-MAC协议增加了65.7%的网络吞吐量,同时降低了30%的接入时延。
基金Supported by the Program for New Century Excellent Talents in University of China under Grant No.NCET-05-0657(新世纪优秀人才支持计划)the Foundation for Distinguished Young Scientists of Hubei Province of China under Grant No.2006ABB028(湖北省青年杰出人才基金)
