睡眠调度技术在无线传感器网络的MAC层协议中的应用分析

无线传感器网络是由大量低成本的传感器节点构成的自组织网络。因为工作环境和成本因素,传感器节点通常不会更换电池,能量十分有限。节能是传感器网络中媒体访问控制（MAC）协议设计的首要问题,节点睡眠调度机制是节能的一个有效手段。文章介绍和分析了S-MAC,T-MAC,D-MAC中的睡眠调度机制的特点,并对未来研究方向提出了展望。     

Dynamic duty cycle and adaptive contention window based QoS-MAC protocol for wireless multimedia sensor networks

Rapid penetration of small, customized wireless devices and enormous growth of wireless communication technologies has already set the stage for large-scale deployment of wireless sensor networks. While the need to minimize the energy consumption has driven significant researches in wireless sensor networks, offering some precise quality of service (QoS) for multimedia transmission over sensor networks has not received significant attention. However, the emerging new applications like video surveillance, telemedicine and traffic monitoring needs transmission of wireless multimedia over sensor networks. Naturally, offering some better QoS for wireless multimedia over sensor networks raises significant challenges. The network needs to cope up with battery-constraints, while providing improved QoS (end-to-end delay and bandwidth requirement). This calls for a suitable sensory MAC protocol capable of achieving application-specific QoS. In this paper, we have proposed a new QoS-based sensory MAC protocol, which not only adapts to application-oriented QoS, but also attempts to conserve energy without violating QoS-constraints. Performance modeling, analysis and simulation results demonstrate that the proposed protocol is capable of providing lower delay and better throughput, at the cost of reasonable energy consumption, in comparison to other existing sensory MAC protocols.     

Rijndael for Sensor Networks: Is Speed the Main Issue?

We present an implementation of Rijndael for wireless sensor networks running on Eyes sensor nodes. In previous works, Rijndael has not been considered a suitable encryption algorithm for sensor nodes because it is too slow and requires a large space in memory, a precious resource in this environment. Our implementation of Rijndael is smaller, from about 1/3 to 1/5 of the size of previous implementations. Furthermore, we observe that nowadays MAC and routing protocols for wireless sensor networks, exhibit latencies up to few seconds, and thus the few milliseconds required by Rijndael to encrypt a TinyOS message are negligible if compared to these latencies. For this reason, in our opinion the main focus on the implementation of encryption algorithms for wireless sensor networks should move from speed, to memory occupation and energy efficiency.     

Using artificial intelligence in routing schemes for wireless networks

For the latest 10 years, many authors have focused their investigations in wireless sensor networks. Different researching issues have been extensively developed: power consumption, MAC protocols, self-organizing network algorithms, data-aggregation schemes, routing protocols, QoS management, etc. Due to the constraints on data processing and power consumption, the use of artificial intelligence has been historically discarded. However, in some special scenarios the features of neural networks are appropriate to develop complex tasks such as path discovery. In this paper, we explore the performance of two very well-known routing paradigms, directed diffusion and Energy-Aware Routing, and our routing algorithm, named SIR, which has the novelty of being based on the introduction of neural networks in every sensor node. Extensive simulations over our wireless sensor network simulator, OLIMPO, have been carried out to study the efficiency of the introduction of neural networks. A comparison of the results obtained with every routing protocol is analyzed. This paper attempts to encourage the use of artificial intelligence techniques in wireless sensor nodes.     

BSC-MAC: Energy efficiency in wireless sensor networks with base station control

Wireless sensor networks (WSNs) are now used in many areas and the interest in this technology continues to increase. Due to the small structure of the processor, the memory of the sensor nodes forming the wireless sensor networks, and as they are operated by a battery, the most important problem appears to be the energy issue. The battery depletion of the sensor nodes randomly deployed in critical areas may negatively interfere with part or all of the network communication and may cause the life of the entire network to terminate. Therefore, many studies have been conducted in the field of energy efficiency. In this study, Base Station Controlled MAC (BSC-MAC), which is a new design of MAC, is recommended. The BSC-MAC protocol presents an adaptive approach for energy efficiency. It determines the nodes on the network as root and source nodes and manages a sleep schedule according to these structures. The simulation of the BSC-MAC protocol was performed with ns-2 and compared to similar protocols, such as adaptive energy efficient MAC (AEEMAC), pattern MAC (P-MAC), and sensor MAC (S-MAC).     

无线传感器网络MAC层能耗与时延的权衡

无线传感器网络节点设计的最重要约束之一就是要求低能耗,这与传统网络依赖持续的能源供应而致力于提供尽可能高的服务质量截然不同.研究了一个结合无线传感器网络的能耗特性而提出的MAC协议S-MAC协议,并在对802.11MAC、S-MAC中的能耗状态与时延特征进行理论和数学分析的基础上,通过仿真实验得出了在模拟网络环境中802.11MAC和S-MAC的能耗和平均时延,S-MAC协议中引入节点周期性睡眠、冲突串音避免和消息传递等新技术,以牺牲时延为代价换取高效的能量利用,提供了一种高效可扩展的在能耗和时延之间进行权衡的方案.     

一种基于无线传感器网络的跨层功率控制策略

为了解决无线传感器网络中节点能源的有限性问题,提出～种跨层的功率控制策略,对基于网络层和基于MAC层的单层功率控制协议进行改进融合。经过仿真实验证明,此方法极大的提高了无线传感器网络的整体性能,有效延长了网络寿命。     

矩形截面矿井巷道三维WSN覆盖机理

无线传感器节点在矿井巷道内壁上多采用径向直线型和径向V字型部署。针对矩形截面矿井巷道的无线传感器节点如何在三维空间实现单重无缝覆盖的问题,通过分析巷道几何尺寸,推导出其节点在两种部署类型中的最小感知半径;进一步推导出其节点覆盖密度与节点感知半径、巷道高度、巷道宽度之间的函数关系,比较两种部署类型节点覆盖密度,为现实运用选择节点部署方式提供有力依据。仿真实验验证了推导结果的正确性。利用推导的结论结合矿井的几何尺寸,可直接计算出节点必须满足的最小感知半径、部署方法、部署位置和覆盖密度,从而提高节点覆盖的有效性,减少工程成本支出。     

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.     

无线传感器网络MAC协议研究进展

在无线传感器网络体系结构中,MAC(medium access control)协议是保证网络高效通信的重要协议.无线传感器网络有着与传统无线网络明显不同的性能特点和技术要求,传统无线网络MAC协议无法应用于传感器网络,各种针对特定传感器网络特点的MAC协议相继提出.归纳无线传感器网络MAC协议的设计原则和分类方法,分析当前典型的各类MAC协议的主要机制,详细比较这些协议的特点、性能差异和应用范围.最后总结无线传感器网络MAC协议的研究现状,指出未来的研究重点.     

一种适用于无线传感器网络的功率控制MAC协议

功率控制技术通过减少节点的发射功率来降低能耗,但节点间不对称的发射功率会增加网络的冲突概率并降低吞吐量.根据实际环境中的节点部署情况,引入了基于Pareto分布的系统模型.研究了传感器网络中功率控制技术在节省能量方面的性能,提出了一种基于SMAC(sensor-MAC)可适用于无线传感器网络的功率控制MAC(media access control)协议.此协议使用功率控制调度算法选择最优相邻节点,使网络中节点的拓扑连接得到优化,在保证网络连通性的同时,降低通信的冲突率,扩大网络的吞吐量.信息的传递以最优功率发射,并使通信节点具有反作用冲突节点的能力,从而在降低网络能耗的同时保证了节点间通信的公平性.实验仿真结果显示,与现有的几种重要方案相比,新的功率控制MAC协议使网络具有了更大的有效吞吐量及更长的生存时间.     

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。     

SEEL:无线传感器网络下自适应、低延迟的节能媒质接入控制协议

无线传感器网络有着广泛的应用前景,然而由于传感器节点能量有限,因此传感器网络上运行的协议必须具备能量有效性以获得较长的生命周期.而媒质接入控制子层是节点能量消耗的主要所在,因此无线传感器网络设计的关键问题之一是媒质的接入控制.提出了一种自适应低延迟的节能MAC协议——SEEL协议,根据当前的网络负载自适应地调节竞争窗口的大小,从而减小节点数据传送的碰撞几率和由于碰撞而导致的能量消耗;采用了快速退避机制,减少了节点在退避过程中的空闲监听时间;扩展了RTS/CTS消息机制,可减少节点在每帧活动阶段的时间以及减小数据的延迟,两者都能节约能量的使用.实验结果显示,SEEL协议具有比S-MAC和TEEM协议更好的性能.     

一种能量有效的移动无线传感器网络MAC协议

基于S-MAC协议改进,利用虚拟簇之间边界节点的调度信息,采用能量有效的二次监听和灵活的调度自适应两个主要方法,设计一种能量有效的移动无线传感器网络MAC协议(EM-MAC),能实现移动节点更有效的更快速的睡眠——唤醒调度自适应。仿真结果表明该协议用于移动无线传感器网络,在能耗、延迟等性能方面有较好提高。     

无线传感网络的冲突感知MAC协议研究

无线传感网络是事件触发的网络，其中包含大量的节点。提出了同源冲突和非同源冲突的概念：将同一事件触发多个节点动作称为同源冲突；不同事件触发的多个节点动作称为非同源冲突。这两种冲突都会造成网络数据流量的下降和节点能量的浪费。因此，需要在现有无线传感的MAC层协议的基础上，实现MAC层的冲突避免。使用筛选和功率控制思想设计了冲突感知MAC协议CAMAC，详细论述了CAMAC对不同类型冲突的处理原理，使用NS进行仿真，并给出了仿真结果。     

基于功率控制的无线传感器网络MAC协议研究

无线传感器网络是21世纪新兴的网络技术,它的出现使网络的发展进入一个新的阶段.近年来,对无线传感器网络介质访问控制协议的研究也越来越多.总结了近年来的研究成果,并针对S-MAC,T-MAC和D-MAC等几种典型的MAC协议进行了对比分析.研究出将功率控制机制引入到MAC协议中可以进一步减少能耗,给出了一种基于发射功率控制思想的MAC协议.PCSMAC协议.功率控制可以从直接的降低发送能量和间接的减少碰撞两个角度节约能耗,是一种有效的节能机制.仿真实验表明,引入功率控制后可以节约能耗达50%--96%左右.     

A framework for use of wireless sensor networks in forest fire detection and monitoring

Forest fires are one of the main causes of environmental degradation nowadays. Current surveillance systems for forest fires lack in supporting real-time monitoring of every point of a region at all times and early detection of fire threats. Solutions using wireless sensor networks, on the other hand, can gather sensory data values, such as temperature and humidity, from all points of a field continuously, day and night, and, provide fresh and accurate data to the fire-fighting center quickly. However, sensor networks face serious obstacles like limited energy resources and high vulnerability to harsh environmental conditions, that have to be considered carefully. In this paper, we propose a comprehensive framework for the use of wireless sensor networks for forest fire detection and monitoring. Our framework includes proposals for the wireless sensor network architecture, sensor deployment scheme, and clustering and communication protocols. The aim of the framework is to detect a fire threat as early as possible and yet consider the energy consumption of the sensor nodes and the environmental conditions that may affect the required activity level of the network. We implemented a simulator to validate and evaluate our proposed framework. Through extensive simulation experiments, we show that our framework can provide fast reaction to forest fires while also consuming energy efficiently.     

网格法在无线传感器网络部署中的应用

传感器节点的数量关系到无线传感器网络的总成本和网络的性能,是设计无线传感器网络优先考虑的问题。对无线传感器网络部署中重点考虑的覆盖、连通性和节能问题进行了讨论,基于网格法对几种不同的传感器部署方案进行分析,计算了它们的有效覆盖面积和有效覆盖率。通过计算和分析可知,传感器按等边三角形部署时,重叠区域小,需要的传感器数量少,是最理想的部署策略。     

一种基于中继节点的线性无线传感器网络数据收集MAC协议

MAC协议对于无线传感器网络的能效是至关重要的。针对线性无线传感器网络设计了一个基于中继节点的数据收集MAC协议SLDMAC。源节点向汇聚节点发送数据时,引入节点能耗因子和剩余能量均衡因子两个参数,通过优化这两个参数,选择合适的中间节点进行中继,从而提升网络的性能。实验结果表明:与DMAC协议相比,SLDMAC协议提升了网络的能效和生存周期。     

三维网络拓扑结构的水声传感器网络MAC协议

水声传感器网络Underwater Acoustic Sensor Network(UWASN)由于其广阔的应用前景,近年来逐渐被人们关注。然而由于水下环境的限制性,水声传感器网络具有其一些独特性。例如,与二维的陆地传感器网络不同,水声传感器网络是三维的。如今,现有的介质访问控制Medium Access Control(MAC)协议大多是针对二维无线传感网络,很少有基于三维水声传感器网络的 MAC 协议。针对水下三维网络,提出了基于三维网络拓扑结构的水声传感器网络 MAC 协议。该协议将网络中的节点生成树结构,并利用子节点与父节点之间的关系,通过动态节点算法实现三维动态的水声传感器网络。此外,详细分析了节点间的碰撞并有效解决各种碰撞,从而大大提高了信道利用率。通过仿真软件对比不同协议在同一网络拓扑中的实验结果,证实文中协议能够有效节约大量能源。