In wireless sensor networks, sensed information is expected to be reliably and timely delivered to a sink in an ad-hoc way. However, it is challenging to achieve this goal because of the highly dynamic topology induce...In wireless sensor networks, sensed information is expected to be reliably and timely delivered to a sink in an ad-hoc way. However, it is challenging to achieve this goal because of the highly dynamic topology induced from asynchronous duty cycles and temporally and spatially varying link quality among nodes. Currently some opportunistic forwarding protocols have been proposed to address the challenge. However, they involve complicated mechanisms to determine the best forwarder at each hop, which incurs heavy overheads for the resource-constrained nodes. In this paper, we propose a light-weight opportunistic forwarding （LWOF） scheme. Different from other recently proposed opportunistic forwarding schemes, LWOF employs neither historical network information nor a contention process to select a forwarder prior to data transmissions. It confines forwarding candidates to an optimized area, and takes advantage of the preamble in low-power-listening （LPL） MAC protocols and dual-channel communication to forward a packet to a unique downstream node towards the sink with a high probability, without making a forwarding decision prior to data transmission. Under LWOF, we optimize LPL MAC protocol to have a shortened preamble （LWMAC）, based on a theoretical analysis on the relationship among preamble length, delivery probability at each hop, node density and sleep duration. Simulation results show that LWOF, along with LWMAC, can achieve relatively good performance in terms of delivery reliability and latency, as a receiver-based opportunistic forwarding protocol, while reducing energy consumption per packet by at least twice.展开更多
在无线传感器网络中,异步低占空比技术可以极大地降低能耗,但是由于节点的低占空比唤醒会造成极大的端到端数据时延。针对这个问题提出一种基于Quorum的异步自适应低占空比路由算法ORDA(Optimal-Reliable delay routing algorithm for l...在无线传感器网络中,异步低占空比技术可以极大地降低能耗,但是由于节点的低占空比唤醒会造成极大的端到端数据时延。针对这个问题提出一种基于Quorum的异步自适应低占空比路由算法ORDA(Optimal-Reliable delay routing algorithm for low duty cycle WSNs based on Quorum),将异步占空比网络和实际链路模型相结合,在异步占空比网络中节点在不同时刻的邻居发现延迟也在不断变化。首先为每个节点根据网络负载选择自身的Quorum类型,并利用Quorum特性来计算邻居节点的重叠时隙个数;然后根据链路质量进一步计算出这一跳范围内邻居节点间的成功转发预期值,并在即将唤醒的节点中选择更可靠的节点转发数据。仿真实验证明,该算法不仅能够降低端到端延迟,而且能获得很好的转发成功率。展开更多
在低占空比无线传感网络中,针对汇聚节点从源节点收集数据所需时间问题进行研究,同时,针对最低时延数据收集(minimum-delay data collection,MDDC)问题,提出了数据收集时延的下限。通过引入虚拟网络模型(virtual network model,VNM),并...在低占空比无线传感网络中,针对汇聚节点从源节点收集数据所需时间问题进行研究,同时,针对最低时延数据收集(minimum-delay data collection,MDDC)问题,提出了数据收集时延的下限。通过引入虚拟网络模型(virtual network model,VNM),并采用最大流方法来解决MDDC问题,提出一种基于最大流的MDDC算法,该算法能获得最低时延及其路径。仿真实验结果表明:相比于Fa ST算法,本文提出的MDDC算法在保持较低能耗的同时,可以有效地降低数据收集时延。展开更多
The lifetime of wireless sensor networks can be improved by imposing low duty cycle, but doing so could not solve unbalanced energy consumption and will increase transmission latency. To avoid this, this paper gives a...The lifetime of wireless sensor networks can be improved by imposing low duty cycle, but doing so could not solve unbalanced energy consumption and will increase transmission latency. To avoid this, this paper gives a new method to collect data by mobile sink. The proper data collection route is selected according to the sink speed and buffer size of the sensors. The sensors only wake up when the sink approaches them. When certain sensors detect an emergency, the sink catches the message quickly and moves to the hotspot to decrease message relay in the network. The result of simulation by OPNET shows that this protocol can reduce transmission data in the network and prolong the network lifetime.展开更多
基金This work is supported in part by the International Science and Technology （S＆T） Cooperation Program of China （ISTCP） under Grant No. 2013DFA10690, and the National Natural Science Foundation of China （NSFC） under Grant Nos. 61672498, 61303246 and 61100180.
文摘In wireless sensor networks, sensed information is expected to be reliably and timely delivered to a sink in an ad-hoc way. However, it is challenging to achieve this goal because of the highly dynamic topology induced from asynchronous duty cycles and temporally and spatially varying link quality among nodes. Currently some opportunistic forwarding protocols have been proposed to address the challenge. However, they involve complicated mechanisms to determine the best forwarder at each hop, which incurs heavy overheads for the resource-constrained nodes. In this paper, we propose a light-weight opportunistic forwarding （LWOF） scheme. Different from other recently proposed opportunistic forwarding schemes, LWOF employs neither historical network information nor a contention process to select a forwarder prior to data transmissions. It confines forwarding candidates to an optimized area, and takes advantage of the preamble in low-power-listening （LPL） MAC protocols and dual-channel communication to forward a packet to a unique downstream node towards the sink with a high probability, without making a forwarding decision prior to data transmission. Under LWOF, we optimize LPL MAC protocol to have a shortened preamble （LWMAC）, based on a theoretical analysis on the relationship among preamble length, delivery probability at each hop, node density and sleep duration. Simulation results show that LWOF, along with LWMAC, can achieve relatively good performance in terms of delivery reliability and latency, as a receiver-based opportunistic forwarding protocol, while reducing energy consumption per packet by at least twice.
文摘在无线传感器网络中,异步低占空比技术可以极大地降低能耗,但是由于节点的低占空比唤醒会造成极大的端到端数据时延。针对这个问题提出一种基于Quorum的异步自适应低占空比路由算法ORDA(Optimal-Reliable delay routing algorithm for low duty cycle WSNs based on Quorum),将异步占空比网络和实际链路模型相结合,在异步占空比网络中节点在不同时刻的邻居发现延迟也在不断变化。首先为每个节点根据网络负载选择自身的Quorum类型,并利用Quorum特性来计算邻居节点的重叠时隙个数;然后根据链路质量进一步计算出这一跳范围内邻居节点间的成功转发预期值,并在即将唤醒的节点中选择更可靠的节点转发数据。仿真实验证明,该算法不仅能够降低端到端延迟,而且能获得很好的转发成功率。
文摘The lifetime of wireless sensor networks can be improved by imposing low duty cycle, but doing so could not solve unbalanced energy consumption and will increase transmission latency. To avoid this, this paper gives a new method to collect data by mobile sink. The proper data collection route is selected according to the sink speed and buffer size of the sensors. The sensors only wake up when the sink approaches them. When certain sensors detect an emergency, the sink catches the message quickly and moves to the hotspot to decrease message relay in the network. The result of simulation by OPNET shows that this protocol can reduce transmission data in the network and prolong the network lifetime.
