一种自适应占空比的WSN MAC协议

PW-MAC 协议中发送者通过预测接收者的醒来时间来最小化传感器节点的能量消耗,但在无陑传感器网络中, PW-MAC协议不能适应大幅流量的变化。为此,提出一种动态调整传感器节点占空比的MAC协议,该协议采用传感器的占空比,根据流量的变化进行动态调整。仿真结果证明,与 PW-MAC 协议陒比,该协议数据包传输延时减少30%,数据包投递率提高35%。     

接收端发起的异步无线传感器网络MAC协议

为了减少无线传感器网络中由于空闲侦听而产生的能量消耗,在接收端发起的介质访问控制(RI-MAC)协议基础上提出一种新的接收端发起的异步RP-MAC。该协议通过预测接收节点唤醒时间,采用随机数作为唤醒间隔,改进RI-MAC的重传机制,从而减少了空闲侦听和网络冲突。NS2仿真结果表明,改进后的MAC协议在在高负载网络中显著降低了节点工作的占空比,提高了包交付率,从而减少了网络能耗。     

一种动态占空比的无线传感器网络MAC协议

在无线传感器网络(WSN)中,降低能耗会引发端到端时延的增加.为兼顾能耗和时延的平衡,提出一种基于动态占空比的WSN介质访问控制协议.通过计算节点利用率、平均睡眠延时,结合占空比上下限,动态调整节点占空比,使其更好地适应网络实时通信流量.实验结果表明,该协议在线性拓扑中比S-MAC节能52％,延迟减少35％,在网状拓扑...     

一种由接收端发起的无线传感器网络MAC协议

在无线传感器网络(Wireless sensor networks,WSN)中,现有的基于接收节点发起的异步MAC层协议,在计算接收节点唤醒时刻时,多采用维持邻居节点的伪随机唤醒时间表的方法。在网络动态负载条件下,此方法不能动态地改变节点唤醒间隔,从而带来较高的数据传输冲突率及较大的数据传输延时。为了解决此问题,本文提出一种新协议HELD-MAC(High energy efficiency and　low delay MAC),保证节点之间具有不同的唤醒时间,同时能够准确预测接收端唤醒时刻,而且接收端可以根据网络负载情况动态改变唤醒间隔。同时为了减轻能量黑洞问题,协议根据节点的剩余能量,自适应地改变节点的最小唤醒间隔。通过仿真对HELD-MAC进行评估,与RI-MAC,PW-MAC等对比,在数据传输延时、能量消耗、网络吞吐量和传输碰撞方面具有较大优势。     

SR-MAC: A Low Latency MAC Protocol for Multi-Packet Transmissions in Wireless Sensor Networks

Event detection is one of the major applications of wireless sensor networks (WSNs). Most of existing medium access control (MAC) protocols are mainly optimized for the situation under which an event only generates one packet on a single sensor node. When an event generates multiple packets on a single node, the performance of these MAC protocols degrades rapidly. In this paper, we present a new synchronous duty-cycle MAC protocol called SR-MAC for the event detection applications in which multiple packets are generated on a single node. SR-MAC introduces a new scheduling mechanism that reserves few time slots during the SLEEP period for the nodes to transmit multiple packets. By this approach, SR-MAC can schedule multiple packets generated by an event on a single node to be forwarded over multiple hops in one operational cycle without collision. We use event delivery latency (EDL) and event delivery ratio (EDR) to measure the event detection capability of the SR-MAC protocol. Through detailed ns-2 simulation, the results show that SR-MAC can achieve lower EDL, higher EDR and higher network throughput with guaranteed energy efficiency compared with R-MAC, DW-MAC and PR-MAC.     

传感器网络中一种基于梯型休眠调度的MAC协议

如何在提供能量高效数据通信的同时满足必要的延迟需求,是无线传感器网络MAC协议面临的一大挑战。本文提出一种基于梯型休眠调度的MAC协议——LP-MAC,通过安排传输路径上的节点连续转发数据从而消除休眠延时;采用冲突避免机制和基于链路计数器的临时唤醒机制,减少兄弟节点间冲突并增加节点休眠时间,进一步提高协议能量效率。理论分析和模拟实验表明,LP-MAC协议既具有低能耗的协议特性,也能保证较低的稳定的端到端延时。     

基于功率控制的无线传感器网络MAC协议研究

本文提出了一种无线传感器网络自适应功率控制MAC协议APC-SMAC。APC-SMAC协议首先通过建立基于最优邻居节点数的功率调度表,提高信道利用率,减少通信能耗,另一方面对干扰节点发送反馈帧控制其进入睡眠,从而提高了网络数据吞吐量,减少了网络延迟。实验结果表明该协议在网络吞吐量、网络时延和平均能耗上均有了较大的提高。     

基于数据重排序的无线传感器网络低延时节能MAC协议

节能,是无线传感器网络最关注的问题之一.让节点进行周期性的侦听与睡眠是一种常用的节能机制.但是,这种节能机制在数据报的传输过程中会引入较长的端到端延时,而且延时与整个周期的长度成正比.提出了一种应用于无线传感器网络的低延时的节能MAC协议:RLL-MAC.该协议在S-MAC/AL(S-MAC with Adaptive Listening)的基础上,增加了数据报重排序机制,即能够根据各个节点工作周期的时序关系,动态的调整数据报的发送次序,从而减少数据报的端到端延迟.通过理论分析和仿真实验表明,与S-MAC/AL相比,RLL-MAC在保持低能耗的同时,极大的降低了端到端延迟.     

SA-MAC: Self-Stabilizing Adaptive MAC Protocol for Wireless Sensor Networks

A common method of prolonging the lifetime of wireless sensor networks is to use low power duty cycling protocol. Existing protocols consist of two categories: sender-initiated and receiver-initiated. In this paper, we present SAMAC, a self-stabilizing adaptive MAC protocol for wireless sensor networks. SA-MAC dynamically adjusts the transmission time-slot, waking up time-slot, and packet detection pattern according to current network working condition, such as packet length and wake-up patterns of neighboring nodes. In the long run, every sensor node will find its own transmission phase so that the network will enter a stable stage when the network load and qualities are static. We conduct extensive experiments to evaluate the energy consumption, packet reception rate of SA-MAC in real sensor networking systems. Our results indicate that SA-MAC outperforms other existing protocols.     

An asynchronous scheduled MAC protocol for wireless sensor networks

Wireless sensor networks (WSNs) comprise a number of autonomous sensors and one or more sinks to cooperatively monitor physical or environmental conditions. Energy efficiency is a key design factor of a MAC protocol for WSNs. Due to the importance of the problem, a number of energy efficient MAC protocols have been developed for WSNs. Preamble-sampling based MAC protocols (e.g., B-MAC and X-MAC) have overheads due to their preambles, and are inefficient at large wakeup intervals. SCP-MAC, a synchronous scheduled energy-efficient scheduling MAC protocol, minimizes the preamble by combining preamble sampling and scheduling techniques; however, it does not prevent energy loss due to overhearing; in addition, due to its synchronization procedure, it results in increased contention and delay. In this paper, we present an energy efficient MAC protocol for WSNs that avoids overhearing and reduces contention and delay by asynchronously scheduling the wakeup time of neighboring nodes. We provide an energy consumption analysis for multi-hop networks. To validate our design and analysis, we implement the proposed scheme in TinyOS. Experimental results show that AS-MAC considerably reduces energy consumption, packet loss and delay when compared with existing energy efficient MAC protocols.     

A stochastic model for beaconless IEEE 802.15.4 MAC operation

IEEE 802.15.4 is a popular choice for MAC/PHY protocols in low power and low data rate wireless sensor networks. In this paper, we develop a stochastic model for the beaconless operation of IEEE 802.15.4 MAC protocol. Given the number of nodes competing for channel access and their packet generation rates, the model predicts the packet loss probability and the packet latency. The model can also account for the impact of hidden nodes in certain situations. We compared the model predictions with NS2 simulation results and found an excellent match between the two for a wide range of the packet generation rates and the number of competing nodes in the network.     

PA-MAC:一种被动的异步低占空比无线传感器网络MAC协议

空闲侦听是无线传感器网络能耗的主要原因之一,而占空比机制是减少空闲侦听能量损耗最主要的方法之一.提出了一种新的无线传感器网络异步MAC协议,称为PA-MAC(Passive Asynchronous MAC),即被动异步MAC.PA-MAC通过采用接收方发起数据传输机制、异步占空比机制以及节点唤醒时间估计机制,降低了节...     

Distributed duty cycle control for delay improvement in wireless sensor networks

Dynamically adjusting the time duration of a node to stay active in one data collection period, i.e., duty cycle, is an efficient strategy to save energy and prolong the lifetime of network. In this paper, we propose a novel Adaptation Duty Cycle Control (ADCC) scheme based on feedback signals for wireless sensor networks (WSNs) which can reduce to-sink data transmission delay while lifetime is also improved. In ADCC, every node adaptively adjusts its duty cycle by comparing its own energy consumption with the largest energy consumption of the entire packet delivery flow, which is stored in a feedback ACK packet generated by sink node. Since in WSNs, a huge number of sensor nodes in the area far from the sink node have much remaining energy when network dies, even up to 90 %, these nodes have much larger duty cycles in ADCC compared with previous schemes, therefore the data transmission delay can be reduced to a great extent. Additionally, ADCC provides a largest-energy notification mechanism in order to determine the appropriate duty cycle of nodes in each data collection flow according to the application-dependent requirements. Comparing with the Wake on Idle, Dual-QCon and the Same Duty Cycle (SDC) schemes, ADCC can reduce the delay by more than 59.5 % under the same network lifetime, or increase the lifetime by 32.8 %–63.4 % under the same delay requirements, while also increase energy efficiency as much as 43.1 %.     

一种超低功耗无线传感器网络MAC协议

在无线传感器网络中,能量是一个关键资源。传感器网络节点通常在大部分时间里处于休眠状态以节约能量。其中,节点间精确地同步和超低的休眠功耗能够本质上延长无线传感器网络节点的寿命。然而现实中节点在唤醒周期设置、时钟源选择和网络节点同步时很难满足理论研究时提出的要求。因此,提出了一种低功耗无线传感器网络MAC协议:允许节点使用多种时钟源实现功耗最优配置,在休眠时采用内部时钟以达到最低功耗,在工作时采用外部晶振以保证射频性能,同时为了解决多时钟源误差增大且休眠周期变化带来的问题,提出了多时钟源休眠唤醒机制和节点同步策略。最后文章在IEEE802.15.4硬件测试平台上完成了多时钟源MAC协议与SMAC协议的实证测试,结果表明对比SMAC协议的唤醒和同步机制,低功耗无线传感器网络MAC协议在传感器网络节点上能够极大地减少休眠功耗并显著地节约同步的时间,从而大大延长节点寿命。     

多个无线传感器网络中节能MAC协议设计

在无线传感器网络中,媒体访问控制(MAC)层协议影响着整个网络的性能。根据无线传感器网络对节点能耗和时延的要求,本文提出了一种基于跨层设计的节能MAC协议。利用物理层、MAC层和路由层之间的信息交互,在保证可靠通信的基础上,实现在一个监听/睡眠周期内数据多跳传输,缩短数据传输时延,并且有效控制网络数据传输的冗余度,降低冗余节点能量消耗。性能分析和仿真结果表明,节能MAC协议能够有效地降低网络时延并且减少节点能耗。     

基于能量的无线传感器网络MAC协议研究

无线传感器网络采用能量有限的电池供电,能量决定了传感器网络的生命期,传感器节点的能耗主要集中在介质访问控制层协议(MAC)上.如何降低传感器网络MAC层协议的能耗,成了解决能量问题的关键.文章从减少数据流量,增加射频模块休眠时间和冲突避免3个方面,深入剖析了当前经典的MAC协议,通过分析得出,在节省能耗上,应该综合考虑各种MAC协议的运用.     

Energy-aware node placement,topology control and MAC scheduling for wireless sensor networks

In the WSNs, the nodes closer to the sink node have heavier traffic load for packet forwarding because they do not only collect data within their sensing range but also relay data for nodes further away. The unbalanced power consumption among sensor nodes may cause network partition. This paper proposes efficient node placement, topology control, and MAC scheduling protocols to prolong the sensor network lifetime, balance the power consumption of sensor nodes, and avoid collision. Firstly, a virtual tree topology is constructed based on Grid-based WSNs. Then two node-placement techniques, namely Distance-based and Density-based deployment schemes, are proposed to balance the power consumption of sensor nodes. Finally, a collision-free MAC scheduling protocol is proposed to prevent the packet transmissions from collision. In addition, extension of the proposed protocols are made from a Grid-based WSN to a randomly deployed WSN, enabling the developed energy-balanced schemes to be generally applied to randomly deployed WSNs. Simulation results reveal that the developed protocols can efficiently balance each sensor node’s power consumption and prolong the network lifetime in both Grid-based and randomly deployed WSNs.     

基于生成树的无线传感器网络MAC协议

简要分析了无线传感器网络(W SNs)MAC层协议,针对MAC协议在节能和时延方面的不足,提出了一种基于生成树的MAC协议(ST-MAC)。以汇聚点为根节点,创建一个由网络中所有节点组成的生成树。ST-MAC采用TDMA接入方式,其固有的低工作周期提高了网络性能。性能分析和实验结果表明:相对S-MAC,ST-MAC在能量节省和时延方面有较好的效果。     

A Light-Weight Opportunistic Forwarding Protocol with Optimized Preamble Length for Low-Duty-Cycle Wireless Sensor Networks

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.     

无线传感器SMAC协议的自适应占空比调整机制研究

针对无线传感器SMAC协议无法适应网络负载的动态变化而导致网络丢包和时延抖动的情况,设计了DSMAC协议.该协议依据数据包在发送队列中等待时间的平均值来预测当前网络的负载情况,并动态地调整节点的占空比,从而在实现能量有效利用的同时保证数据的及时可靠传输.仿真实验表明,改进后的协议能有效地利用了节点能量,同时增加了网络吞吐量,降低了数据端到端的时延.