Energy-efficiency clustering protocol in wireless sensor networks

The conventional clustering method has the unique potential to be the framework for power-conserving ad hoc networks. In this environment, studies on energy-efficient strategies such as sleeping mode and redirection have been reported, and recently some have even been adopted by some standards like Bluetooth and IEEE 802.11. However, consider wireless sensor networks. The devices employed are power-limited in nature, introducing the conventional clustering approach to the sensor networks provides a unique challenge due to the fact that cluster-heads, which are communication centers by default, tend to be heavily utilized and thus drained of their battery power rapidly. In this paper, we introduce a re-clustering strategy and a redirection scheme for cluster-based wireless sensor networks in order to address the power-conserving issues in such networks, while maintaining the merits of a clustering approach. Based on a practical energy model, simulation results show that the improved clustering method can obtain a longer lifetime when compared with the conventional clustering method.     

A dual-mode energy efficient encryption protocol for wireless sensor networks

This paper presents a novel link-layer encryption protocol for wireless sensor networks. The protocol design aims to reduce energy consumption by reducing security related communication overhead. This is done by merging security related data of consecutive packets. The merging (or combining packets) based on simple mathematical operations helps to reduce energy consumption by eliminating the requirement to send security related fields in headers and trailers. We name our protocol as the Compact Security Protocol referred to as C-Sec. In addition to energy savings, the C-Sec protocol also includes a unique security feature of hiding the packet header information. This feature makes it more difficult to trace the flow of wireless communication, and helps to minimize the cost of defending against replay attacks. We performed rigorous testing of the C-Sec protocol and compared it with well-known protocols including TinySec, MiniSec, SNEP and Zigbee. Our performance evaluation demonstrates that the C-Sec protocol outperforms other protocols in terms of energy savings. We also evaluated our protocol with respect to other performance metrics including queuing delay and error probability.     

Clamp-and-Forget: A self-sustainable non-invasive wireless sensor node for smart metering applications

Measuring and managing the power consumption of household appliances, as well as that of industrial machineries, is becoming more and more important to improve the distribution and usage of the electrical energy and to reduce the energy bill. We present the design of a non-invasive wireless current meter which can measure AC current up to $60A_{\mathit{RMS}}$ exploiting a small clamp-on inductive sensor. The novelty of the design is a subsystem consisting of a harvesting circuit designed to extract energy from the same current transducer used for measurements. Experiments have been conducted to validate the approach, to assess the accuracy of the sensing system and deviations due to the energy harvester, and to determine the condition which permits us to achieve the energy neutrality and thus, a self-sustainable smart meter.     

Energy-balanced unequal clustering protocol for wireless sensor networks

Clustering provides an effective way to prolong the lifetime of wireless sensor networks.One of the major issues of a clustering protocol is selecting an optimal group of sensor nodes as the cluster heads to divide the network.Another is the mode of inter-cluster communication.In this paper,an energy-balanced unequal clustering(EBUC)protocol is proposed and evaluated.By using the particle swarm optimization(PSO)algorithm,EBUC partitions all nodes into clusters of unequal size,in which the clusters closer to the base station have smaller size.The cluster heads of these clusters can preserve some more energy for the inter-cluster relay traffic and the 'hot-spots' problem can be avoided.For inter-cluster communication,EBUC adopts an energy-aware multihop routing to reduce the energy consumption of the cluster heads.Simulation results demonstrate that the protocol can efficiently decrease the dead speed of the nodes and prolong the network lifetime.     

基于形式化技术的帧中继拥塞控制协议一致性测试

帧中继作为重要的广域网协议得到了日益广泛的应用，但是相关的测试活动却非常有限。本文在深入分析了帧中继拥塞控制协议的基础上对其进行了一致测试研究和实际测试。针对帧中继拥塞控制协议的特点，采用穿越测试法设计生成了基于形式化技术的一致性测试集，并且将利用协议集成测试系统取得一致性测试的研究成果应用到路由器的开发和研制过程中。     

基于网格分簇的无线传感器网络节能算法

无线传感器网络中,能量消耗问题一直最受人们关注.为了节省网络能量,针对现有算法存在的冗余节点过多以及能量利用率较低等问题,在以往算法的基础上,提出了一种基于网格分簇的节能算法,即基于网格分簇的无线传感器网络节能算法EABGC(Energy-saving Algorithm Based on Grid Clustering).该算法采用虚拟网格和贪婪算法等来节约网络能量.通过仿真实验,该算法与LEACH协议相比,能减少网络的能量消耗,从而达到节能的目的.EABGC算法,能有效地降低网络消耗,实现节能效果.     

Design guidelines for wireless sensor networks: communication, clustering and aggregation

When sensor nodes are organized in clusters, they could use either single hop or multi-hop mode of communication to send their data to their respective cluster heads. We present a systematic cost-based analysis of both the modes, and provide results that could serve as guidelines to decide which mode should be used for given settings. We determine closed form expressions for the required number of cluster heads and the required battery energy of nodes for both the modes. We also propose a hybrid communication mode which is a combination of single hop and multi-hop modes, and which is more cost-effective than either of the two modes. Our problem formulation also allows for the application to be taken into account in the overall design problem through a data aggregation model.     

A synchronous duty-cycled reservation based MAC protocol for underwater wireless sensor networks

To design an energy-efficient Medium Access Control (MAC) protocol for the Underwater Wireless Sensor Networks (UWSNs) is an urgent research issue since depleted batteries cannot be recharged or replaced in the underwater environment. Moreover, the underwater acoustic channels are affected by hindrances such as long propagation delay and limited bandwidth, which appear in the design of the MAC protocol for the UWSNs. The available MAC protocols for the terrestrial wireless sensor networks exhibit low performance in energy efficiency, throughput and reliability in the UWSNs, and cannot be used in the UWSNs directly because of their unique characteristics. This paper proposes a synchronous duty-cycled reservation-based MAC protocol named Ordered Contention MAC (OCMAC) protocol. The basic mechanism of this protocol is to schedule data transmission by transmitters through the scheduling of Ready To Send (RTS) frames. The protocol eliminates the possible collision during data transmission and improves communication efficiency. The paper analyzes the performance in energy efficiency, throughput and reliability of the protocol by modeling the queuing behavior of OCMAC with a Markov Chain process. Furthermore, the analytical model is validated through a simulation study. The analysis results demonstrated that while providing good throughput and reliability, OCMAC can achieve energy saving.     

An Energy Conservation MAC Protocol in Wireless Sensor Networks

Wireless sensor networks use battery-operated computing and sensing devices. Because of the limitation of battery power in the sensor nodes, energy conservation is a crucial issue in wireless sensor networks. Consequently, there is much literature presenting energy-efficient MAC protocols based on active/sleep duty cycle mechanisms to conserve energy. Convergecast is a common communication pattern across many sensor network applications featuring data gathering from many different source nodes to a single sink node. This leads to high data collision rates, high energy consumption, and low throughput near the sink node. This paper proposes an efficient slot reservation MAC protocol to reduce energy consumption and to make transmission more efficient in data gathering wireless sensor networks. The simulation results show that our protocol provides high throughput, low delivery latency and low energy consumption compared to other methods.

Photovoltaic scavenging systems: Modeling and optimization

The interest in embedded portable systems and wireless sensor networks (WSNs) that scavenge energy from the environment has been increasing over the last years. Thanks to the progress in the design of low-power circuits, such devices consume less and less power and are promising candidates to perform continued operation by the use of renewable energy sources. The adoption of maximum power point tracking (MPPT) techniques in photovoltaic scavengers increases the energy harvesting efficiency and leads to several benefits such as the possibility to shrink the size of photovoltaic modules and energy reservoirs. Unfortunately, the optimization of this process under non-stationary light conditions is still a key design challenge and the development of a photovoltaic harvester has to be preceded by extensive simulations. We propose a detailed model of the solar cell that predicts the instantaneous power collected by the panel and improves the simulation of harvester systems. Furthermore, the paper focuses on a methodology for optimizing the design of MPPT solar harvesters for self-powered embedded systems and presents improvements in the circuit architecture with respect to our previous implementation. Experimental results show that the proposed design guidelines allow to increment global efficiency and to reduce the power consumption of the scavenger.     

Modulated relay based stable election protocol for large-scale wireless sensor networks

Internet of things (IoT) applications based on wireless sensor networks (WSNs) have recently gained vast momentum. These applications vary from health care, smart cities, and military applications to environmental monitoring and disaster prevention. As a result, energy consumption and network lifetime have become the most critical research area of WSNs. Through energy-efficient routing protocols, it is possible to reduce energy consumption and extend the network lifetime for WSNs. Using hybrid routing protocols that incorporate multiple transmission methods is an effective way to improve network performance. This paper proposes modulated R-SEP (MR-SEP) for large-scale WSN-based IoT applications. MR-SEP is based on the well-known stable election protocol (SEP). MR-SEP defines three initial energy levels for the nodes to improve the network energy distribution and establishes multi-hop communication between the cluster heads (CHs) and the base station (BS) through relay nodes (RNs) to reduce the energy consumption of the nodes to reach the BS. In addition, MR-SEP reduces the replacement frequency of CHs, which helps increase network lifetime and decrease power consumption. Simulation results show that MR-SEP outperforms SEP, LEACH, and DEEC protocols by 70.2%, 71.58%, and 74.3%, respectively, in terms of lifetime and by 86.53%, 86.68%, and 86.93% in terms of throughput.     

一种全新的基于纠缠交换的量子中继策略

利用纠缠作为资源的量子通信协议具有安全性好、可靠性高、使用灵活等优势,具有广阔的发展前景,同时也对纠缠光子的保真度提出了一定的要求.提出了一种基于纠缠交换的量子中继策略,在远距离通信者之间设置多级中继,借助经典通信的辅助作用,通过节点间的纠缠交换和纠缠纯化操作为收发双方提供保真度稳定的长程纠缠连接.性能分析表明,通过合理控制中继级数和提高纠缠交换以及纠缠纯化的成功率,可以显著降低系统时延和提高系统吞吐量,为实现全球量子通信提供必不可少的纠缠资源.     

无线传感器网络分簇路由协议研究

在无线传感器网络中,分簇型路由在路由协议中占据重要的地位,该协议方便拓扑结构管理,能源利用率高,数据融合简单。文章从簇头生成、簇形成和簇路由3个角度对典型的分簇路由算法LEACH,HEED,EEUC,PEGASIS进行了系统描述,从网络生命周期和节点存活数量等方面,对比了其优缺点,结合该领域的研究现状,指出了未来研究的方向。     

A power management system for energy harvesting and wireless sensor networks application based on a novel charge pump circuit

Energy Harvesting circuits are developed as an alternative solution to supply energy to autonomous sensor nodes in Wireless Sensor Networks. In this context, this paper presents a micro-power management system for multi energy sources based on a novel design of charge pump circuit to allow the total autonomy of self-powered sensors. This work proposes a low-voltage and high performance charge pump (CP) suitable for implementation in standard complementary metal oxide semiconductor (CMOS) technologies. The CP design was implemented using Cadence Virtuoso with AMS 0.35μm CMOS technology parameters. Its active area is 0.112 mm². Consistent results were obtained between the measured findings of the chip testing and the simulation results. The circuit can operate with an 800 mV supply and generate a boosted output voltage of 2.835 V with 1 MHz as frequency.     

WiMAX下优化中继站切换策略研究

针对IEEE 802．16e标准中中继站没有被考虑的问题,提出了一种优化信息管理和交换过程的方法。在此过程中允许目标Bs对切换消息进行处理,从而减少用户信息管理的开销并获得最大的吞吐量。     

Energy Efficient Non-uniform Clustering Division Scheme in Wireless Sensor Networks

Wireless sensor networks can be used to monitor the interested region by multi-hop communication. Since sensor nodes are equipped with energy-limited batteries, energy conservation in such networks is of paramount importance in order to prolong the network lifetime. In this paper, considering the constrained radio range of node, we propose an energy efficient clustering division scheme from the viewpoint of energy consumption. The difference between our scheme and previous schemes is that ours is a non-uniform clustering hierarchy. With the algorithm that is proposed by this paper, we can divide the cluster into multiple non-uniform concentric rings and obtain the optimal thickness of each ring. Motivated by the derived results, every sensor node can adjust its radio range for transmission. Our extensive simulation results indicate that the proposed non-uniform clustering division scheme outperforms the conventional uniform clustering division schemes in terms of energy consumption and lifetime. The future research that should be explored is also discussed finally.

Performance analysis of a new random access protocol for OCDMA networks

A New random access protocol for OC-DMA networks is proposed in this paper. Employing a new mathematical model, namely the processor-sharing system, steady-state throughput ratio and average delay of OCDMA networks are calculated. The results reveal that our protocol outperforms other existing protocols. Meanwhile, we investigate the performance of OCDMA networks by altering the code parameters, i.e., length and weight, and the maximum number of active users in the system, corresponding results are indeed consistent with the practical situation. In addition, the analysis is simplified compared with the conventional Markov chain model. Thus the processor-sharing system is truly applicable to model OCDMA networks. Supported by National Natural Science Foundation of China (NSFC), No. 60472035.     

一种基于RIP和帧中继的网络设计

广域网和以太网是两种不同的网络技术,而小型局域网因为其业务多样性和分布离散性,使得其需要兼容不同协议的网络。提出一种基于以太网RIP路由协议和广域网的帧中继协议的网络设计,满足不同协议互通,为不同核心路由器和交换机之间配置RIP路由、静态默认路由和帧中继子接口,最终完成了该网络的布置。     

An enhanced MAC protocol based on the IEEE 802.11 for data relay satellite systems

Data relay satellite (DRS) systems play an important role in space information networks. Characterized by highly dynamic topology and discontinuous communication links, it is suggested that the IEEE 802.11 protocol employed in such a network could be more flexible. However, such a terrestrial network protocol could not be applied to DRS systems directly, nor supports a fast response due to the long propagation delay and severe packet collision. To address this challenge, we proposed an enhanced media access control (MAC) protocol based on the IEEE 802.11 protocol providing multiaccess for low earth orbit (LEO) distributed constellations. In this paper, we investigated the access delay performance of the proposed protocol in our model. Then, we derived a contention window adaption by using an iteration algorithm that can dynamically adjust the values of the contention window depending on the number of user satellites in the communication coverage. Simulation results show that the average access delay does not exceed 20 seconds, which is significantly lower than the standard protocol. Moreover, the traffic threshold is increased to 0.6, and the maximum throughput has doubled compared with the standard protocol. It is proved that the enhanced MAC protocol shows a better performance in DRS systems.