认知无线电传感器网络中能量有效的感知策略

将认知无线电技术引入无线传感器网络(WSN),可以使传感器节点在不影响主用户正常通信的前提下,利用频谱空穴来满足自身的通信需求。虽然切换到合适的信道能够降低传输能耗,但是感知过程不可避免的带来一定的额外能耗,因此如何对频谱进行感知来降低节点的总能耗是一个至关重要的问题。在基于离散马尔可夫链的信道占用模型基础上,根据信道状态的n步转移概率,提出了一种由当前感知结果来决定下一次感知时刻的感知策略。仿真结果表明,相对传统无感知过程的WSN以及先感知后传输的策略,有效地降低了能耗。     

无线传感器网络路由协议与改进

详细介绍无线传感器网络(WSN)的两种代表性协议:信息协商传感器(SPIN)协议和低能量自适应分簇路由(LEACH)协议的概念、原理和优缺点.提出路由协议中需要进一步解决的问题.改进的WSN路由算法应尽可能降低节点能耗.以延长网络生存时间.     

脉冲耦合和分布式扩散相结合的时间同步协议

针对WSN同步精度较低、可扩展性差的问题,提出基于脉冲耦合和分布式扩散相结合的协作时间同步协议,将同步分为时钟节拍同步和时间同步两个阶段。时钟节拍同步阶段,通过脉冲信号耦合来改变节点相位实现节拍同步;时间同步阶段,基于双向信息交换模式,把主节点域的平均时间扩散有限的跳数,采用互扩散使节点时间近似同步到网络节点的平均时间上,实现时间同步。结果表明:该协议同步精度更高,收敛速度较快,扩展性较好。     

具有四个输出并基于微处理器的双定时器

基于Freescale半导体公司MCC908QY型8位闪存微型计算机的图1所示电路，可提供一个低成本通用双定时器．该定时器可代替单触发电路。您可以通过修改汇编语言软件来满足特定应用要求。该电路采用微处理器IC1的内部12．8MHz时钟振荡器。内部时钟除以4即获得3．2MHz时钟频率，此频率进一步除以定时器预定比例64即获得50kHz时钟。将定时器模数计数器除以50000．可获得可产生1次／秒实时中断与主定时间隔的1Hz时基。     

低功耗wirelessHART网络时钟同步

提出一种基于TPSN(Timing-Sync Protocol for Sensor Networks)的WirelessHART网络时钟同步协议改进措施。通过在原有TPSN协议上添加线性回归法估计通信节点间的时钟偏差以延长时钟同步周期并针对工厂存在强干扰,协议添加异常情况处理机制以减少坏点出现概率。经过WirelessHART通信节点平台测试,改进时钟同步协议的时钟同步周期相对TPSN协议延长百分之十,因此,该改进协议达到有效降低节点功耗的目的。     

用STC12C5410AD单片机设计数字音乐闹钟

通常,利用单片机内部定时器作为时钟基准,无需附加外部组件,通过软件编程和CPU内部的中断能够实现实时时钟功能。这种方法简单易行、成本低,但缺点也非常明显。一方面计时功能有限,另一方面由于CPU主晶振与电容的影响,累积误差较大。     

基于LEACH路由协议的WSN能耗计算

介绍了WSN的路由协议与能量管理的关系,对基于LEACH协议的WSN进行了能耗计算与分析.结果表明,通过聚类所形成的层次型结构,适当选取簇头数目,有利于降低网络能耗,延长网络生命周期.但节点布局,簇头节点的数据融合对网络能耗的影响还需进一步探讨.     

一种改进PBS的无线传感器网络时钟同步方法SCRT

针对无线传感器网络使用PBS方法进行时钟同步时传感器节点同步范围受限的问题,提出一种改进PBS的无线传感网络时钟同步方法 SCRT。该方法结合发送者-接收者(SR)和仅接收者(RO)两种同步,使得分组成簇网络中簇头节点通过与参考节点交换时钟消息、成员节点根据簇头发送和接收时钟消息内携带的参考时间戳调节本地时钟,从而达到时钟同步。时钟偏移估计、频率偏移估计与计算出的克拉美罗界通过Matlab钟同步方法与PBS方案相比,增大了节点的同步范围、显著降低了整个网络的同步误差且提高了同步效率。     

异质节点分离CRSN中MAC协议设计与性能分析

认知无线传感器网络(CRSN)是一种将认知无线电(CR)技术引入传统WSN中的新型网络,具有一定的应用价值和发展前景.然而,CRSN中的认知功能带来的额外能耗和处理要求及其高成本实现,阻碍了它的进一步发展及应用.基于此,提出将认知功能迁移到另外一类节点——认知节点,并使其拥有较强的处理能力和能量收集能力.认知节点与普通传感器节点按照一定比例进行部署,组成另外一种新型网络——异质节点CRSN (HT-CRSN),这种新型网络能够提高网络性能并降低部署成本.并提出了一种能够适用于这种异质节点传感器网络的工作时序及其一系列可行性的MAC协议(FBP等).通过对所提MAC协议的能耗分析,说明可以通过调整两类异质节点的部署比例和能量收集速率均衡两类异质节点的能耗,进而提高网络生命周期.     

任意波发生器的研究与设计

在任意波形发生器设计中,DDS技术具有成本低、功耗小、分辨率高和切换时间快等优点,但波形形状任意可编辑性较差;软件无线电技术可产生任意复杂波形,但切换时间慢。采用DDS和软件无线电相结合的技术,正弦波、三角波、方波等普通信号的产生用DDS实现;复杂无规则波形信号的产生用软件无线电实现;最后任意波形发生器通过波形存储器、相位累加器、取样时钟发生器、地址发生器等硬件平台设计和软件波形算法设计来共同完成。     

Energy Efficient Energy Hole Repelling (EEEHR) Algorithm for Delay Tolerant Wireless Sensor Network

Reducing energy consumption and increasing network lifetime are the major concerns in Wireless Sensor Network (WSN). Increase in network lifetime reduces the frequency of recharging and replacing batteries of the sensor node. The key factors influencing energy consumption are distance and number of bits transmitted inside the network. The problem of energy hole and hotspot inside the network make neighbouring nodes unusable even if the node is efficient for data transmission. Energy Efficient Energy Hole Repelling (EEEHR) routing algorithm is developed to solve the problem. Smaller clusters are formed near the sink and clusters of larger size are made with nodes far from the sink. This methodology promotes equal sharing of load repelling energy hole and hotspot issues. The opportunity of being a Cluster Head (CH) is given to a node with high residual energy, very low intra cluster distance in case of nodes far away from the sink and very low CH to sink distance for the nodes one hop from the sink. The proposed algorithm is compared with LEACH, LEACH-C and SEP routing protocol to prove its novel working. The proposed EEEHR routing algorithm provides improved lifetime, throughput and less packet drop. The proposed algorithm also reduces energy hole and hotspot problem in the network.     

Energy-efficient neighbor discovery protocol for mobile wireless sensor networks

Low energy consumption is a critical design requirement for most wireless sensor network (WSN) applications. Due to minimal transmission power levels, time-varying environmental factors and mobility of nodes, network neighborhood changes frequently. In these conditions, the most critical issue for energy is to minimize the transactions and time consumed for neighbor discovery operations. In this paper, we present an energy-efficient neighbor discovery protocol targeted at synchronized low duty-cycle medium access control (MAC) schemes such as IEEE 802.15.4 and S-MAC. The protocol effectively reduces the need for costly network scans by proactively distributing node schedule information in MAC protocol beacons and by using this information for establishing new communication links. Energy consumption is further reduced by optimizing the beacon transmission rate. The protocol is validated by performance analysis and experimental measurements with physical WSN prototypes. Experimental results show that the protocol can reduce node energy consumption up to 80% at 1–3 m/s node mobility.     

基于改进SSA优化WSN分簇协议

无线传感器网络(Wireless Sensor Networks,WSN)的路由协议是无线传感器网络领域中的一个研究热点.针对LEACH协议的不足,提出一种基于自适应t分布改进麻雀搜索算法(Improved Sparrow Search Algorithm,ISSA)的改进LEACH协议(LEACH?ISSA),以解决...     

WSNSec: A scalable data link layer security protocol for WSNs

A Wireless Sensor Network (WSN) link layer security protocol called WSNSec is proposed in this paper. The effective usage of limited sensor node resources is of high importance in WSN security protocol design and implementation. In addition, research on increased security for the WSNs employed in especially military and health areas recently receives a remarkable attention as primarily focused on in this presented work. The WSNSec smoothly combines the advantageous aspects of the Scalable Encryption Algorithm (SEA) with the Counter Mode (CTR) and Cipher Block Chaining-Message Authentication Code (CBC-MAC) approaches. It provides not only high data confidentiality but also message authentication and integrity functions. The WSNSec security level can be boosted dynamically if required. It has been shown that using the proposed WSNSec with the 192-bit data block/key size has a trivial increase on the memory usage and energy consumption while providing an extremely high level of security compared to the traditional TinySEC. In addition, modeling and simulation of a WSN employing the proposed WSNSec have been realized using the OPNET Modeler software. The simulation results reveal that the ratios of the delays resulted from the particular use of both WSNSec and TinySEC to the total end to end delays converge at 13% for increasing the network load. Therefore the WSNSec provides a better delay performance in highly scalable applications.     

无线传感器网络UDHR协议的设计与实现

针对无线传感器网络(WSN)数据流的特点,提出一种WSN上下行路由异构的协议(UDHR),上下行路由可采用不同的算法,适合于时间驱动、事件驱动以及查询的数据收集模式.利用OMNeT++平台对UDHR协议进行建模仿真,结果表明该协议开销小、扩展性好、健壮稳定.并且在自主开发的Testbed平台上实现了该路由协议,利用该平台可实时观察整个WSN网络拓扑变化、网络开销、监测每个节点能量消耗以及数据收集等情况.     

Double Cluster Based Energy Efficient Routing Protocol for Wireless Sensor Network

Reducing the energy consumption of sensor nodes and prolonging the life of the network is the central topic in the research of wireless sensor network (WSN) protocol. The low-energy adaptive clustering hierarchy (LEACH) is one of the hierarchical routing protocols designed for communication in WSNs. LEACH is clustering based protocol that utilizes randomized rotation of local cluster-heads to evenly distribute the energy load among the sensors in the network. But LEACH is based on the assumption that each sensor nodes contain equal amount of energy which is not valid in real scenarios. A developed routing protocol named as DL-LEACH is proposed. The DL-LEACH protocol cluster head election considers residual energy of nodes, distance from node to the base station and neighbor nodes, which makes cluster head election reasonable and node energy consumption balance. The simulation results of proposed protocols are compared for its network life time in MATLAB with LEACH protocol. The DL-LEACH is prolong the network life cycle by 75 % than LEACH.     

基于LEACH的WSN节能改进及仿真

如何节约能量,一直是无线传感器网络(WSN)的关键问题.通过将能量问题与无线传感器网络的通信协议进行结合,在低能量自适应聚类(LEACH)协议的基础上进行可行的改进,并采用NS2进行仿真验证.仿真结果表明,与原来的协议LEACH相比,改进后的协议L-NEW能有效地平衡节点能量消耗,延长了网络的生存时间.     

Relay node selection scheme and deep sleep period for power management in energy-harvesting wireless sensor networks

This paper presents Relay node selection scheme and Deep sleep period for power management in Energy Harvesting Wireless Sensor Networks (RD-EHWSN), a new energy-saving scheme founded on asynchronous duty cycling. RD-EHWSN reduces sensor node energy consumption and guarantees equilibrium energy use between sensor nodes in WSN with the energy harvesting capacity by adjusting these sensor nodes duty cycles more drastically and deeply by according to the estimated value of its residual energy on the basis of future-presented harvested energy, and this is done through the use of a new proposed energy threshold policy. RD-EHWSN also grips the benefit of transmitter initiated using the low power listening (LPL) technique with short preamble messages and uses a new relay node selection procedure to achieve the load balancing in WSN. We implemented RD-EHWSN by using OMNeT++/MiXiM. For evaluation, we compared it with PS-EHWSN, under multiple concurrent multihop traffic flows scenarios and scenarios in which nodes can harvest different energy harvesting rate. In all experiments, RD-EHWSN significantly outperformed the PS-EHWSN scheme; the results of simulation demonstrate that our scheme enhances the general yielding of WSN thru lessening the energy consumption and the mean latency, as well as raising the packet delivery ratio and the throughput. Moreover, RD-EHWSN improves the WSN lifetime and ensures it operates in good condition in the case where the energy harvesting rate is lower by comparing it with the PS-EHWSN scheme.     

An adaptive‐aware energy and queue improvement of AOMDV

Because the node energy and network resources in the wireless sensor network (WSN) are very finite, it is necessary to distribute data traffic reasonably and achieve network load balancing. Ad hoc on‐demand multipath distance vector (AOMDV) is a widely used routing protocol in WSN, but it has some deficiencies: establishes the route by only using hop counts as the routing criterion without considering other factors such as energy consumption and network load; forwards route request in fixed delay resulting in building the nonoptimal path; and cannot update the path status after built paths. For the deficiency of AOMDV, this paper proposes a multipath routing protocol adaptive energy and queue AOMDV (AEQAOMDV) based on adaptively sensing node residual energy and buffer queue length. When sending a routing request, the forwarding delay of the routing request is adaptively adjusted by both the residual energy and the queue length of the intermediate node; when establishing routes, a fitness is defined as a routing criterion according to the link energy and the queue load, predicting the available duration of the node based on the energy consumption rate and adjusting the weight of the routing criterion by the available duration of the node; after the routes are established, the path information status are updated via periodically broadcasting Hello that carries the path information with the minimum fitness, making the source node update the path information periodically. By using NS‐2, simulations demonstrate that compared with AOMDV, AEQAOMDV has obvious improvements in increasing packet delivery ratio, reducing network routing overhead, reducing route discovery frequency, and decreasing the network delay. And AEQAOMDV is more suitable for WSN.     

A novel residual energy‐based distributed clustering and routing approach for performance study of wireless sensor network

Non‐uniform energy consumption during operation of a cluster‐based routing protocol for large‐scale wireless sensor networks (WSN) is major area of concern. Unbalanced energy consumption in the wireless network results in early node death and reduces the network lifetime. This is because nodes near the sink are overloaded in terms of data traffic compared with the far away nodes resulting in node deaths. In this work, a novel residual energy–based distributed clustering and routing (REDCR) protocol has been proposed, which allows multi‐hop communication based on cuckoo‐search (CS) algorithm and low‐energy adaptive‐clustering–hierarchy (LEACH) protocol. LEACH protocol allows choice of possible cluster heads by rotation at every round of data transmission by a newly developed objective function based on residual energy of the nodes. The information about the location and energy of the nodes is forwarded to the sink node where CS algorithm is implemented to choose optimal number of cluster heads and their positions in the network. This approach helps in uniform distribution of the cluster heads throughout the network and enhances the network stability. Several case studies have been performed by varying the position of the base stations and by changing the number of nodes in the area of application. The proposed REDCR protocol shows significant improvement by an average of 15% for network throughput, 25% for network scalability, 30% for network stability, 33% for residual energy conservation, and 60% for network lifetime proving this approach to be more acceptable one in near future.