鲁棒的无线传感器网络空间范围聚集查询处理算法

现有无线传感器网络环境下的空间范围聚集查询处理算法没有综合考虑节点移动、节点失效和通信链路失效等因素对查询处理的影响,导致查询成功率低和能量消耗大.本文提出了利用节点冗余保证查询处理过程鲁棒性的空间范围聚集查询处理算法RSA(Robust Spatial window aggregation query processing Algorithm),它将查询区域划分为若干个网格,沿一条路线依次收集各网格内所有节点的数据.RSA算法给出了一种自适应的网格大小设置方法和基于网格面积的网格代表节点选择策略,以减少算法的能量消耗和提高查询成功率;给出了基于目标矩形的方法以绕过不存在节点的区域,从而避免查询处理过程出现中断.仿真实验结果表明,RSA算法优于现有的IWQE算法.     

An energy‐efficient utility‐based distributed data routing scheme for heterogenous sensor networks

A utility‐based distributed data routing algorithm is proposed and evaluated for heterogeneous wireless sensor networks. It is energy efficient and is based on a game‐theoretic heuristic load‐balancing approach. It runs on a hierarchical graph arranged as a tree with parents and children. Sensor nodes are considered heterogeneous in terms of their generated traffic, residual energy and data transmission rate and the bandwidth they provide to their children for communication. The proposed method generates a data routing tree in which child nodes are joined to parent nodes in an energy‐efficient way. The principles of the Stackelberg game, in which parents as leaders and children as followers, are used to support the distributive nature of sensor networks. In this context, parents behave cooperatively and help other parents to adjust their loads, while children act selfishly. Simulation results indicate the proposed method can produce on average more load‐balanced trees, resulting in over 30% longer network lifetime compared with the cumulative algorithm proposed in the literature. Copyright © 2014 John Wiley & Sons, Ltd.     

Energy‐Efficient Quorum‐Based MAC Protocol for Wireless Sensor Networks

The reliability of sensor networks is generally dependent on the battery power of the sensor nodes that it employs; hence it is crucial for the sensor nodes to efficiently use their battery resources. This research paper presents a method to increase the reliability of sensor nodes by constructing a connected dominating tree (CDT), which is a subnetwork of wireless sensor networks. It detects the minimum number of dominatees, dominators, forwarder sensor nodes, and aggregates, as well as transmitting data to the sink. A new medium access control (MAC) protocol, called Homogenous Quorum‐Based Medium Access Control (HQMAC), is also introduced, which is an adaptive, homogenous, asynchronous quorum‐based MAC protocol. In this protocol, certain sensor nodes belonging to a network will be allowed to tune their wake‐up and sleep intervals, based on their own traffic load. A new quorum system, named BiQuorum, is used by HQMAC to provide a low duty cycle, low network sensibility, and a high number of rendezvous points when compared with other quorum systems such as grid and dygrid. Both the theoretical results and the simulation results proved that the proposed HQMAC (when applied to a CDT) facilitates low transmission latency, high delivery ratio, and low energy consumption, thus extending the lifetime of the network it serves.     

A particle swarm optimization based energy efficient cluster head selection algorithm for wireless sensor networks

Clustering has been proven to be one of the most efficient techniques for saving energy of wireless sensor networks (WSNs). However, in a hierarchical cluster based WSN, cluster heads (CHs) consume more energy due to extra overload for receiving and aggregating the data from their member sensor nodes and transmitting the aggregated data to the base station. Therefore, the proper selection of CHs plays vital role to conserve the energy of sensor nodes for prolonging the lifetime of WSNs. In this paper, we propose an energy efficient cluster head selection algorithm which is based on particle swarm optimization (PSO) called PSO-ECHS. The algorithm is developed with an efficient scheme of particle encoding and fitness function. For the energy efficiency of the proposed PSO approach, we consider various parameters such as intra-cluster distance, sink distance and residual energy of sensor nodes. We also present cluster formation in which non-cluster head sensor nodes join their CHs based on derived weight function. The algorithm is tested extensively on various scenarios of WSNs, varying number of sensor nodes and the CHs. The results are compared with some existing algorithms to demonstrate the superiority of the proposed algorithm.     

无线传感器网络中基于监督的安全数据融合方法

In order to avoid internal attacks during data aggregation in wireless sensor networks, a grid-based network architecture fit for monitoring is designed and the algorithms for network division, initialization and grid tree construction are presented. The characteristics of on-off attacks are first studied and monitoring mechanisms are then designed for sensor nodes. A Fast Detection and Slow Recovery (FDSR) algorithm is proposed to prevent on-off attacks by observing the behaviors of the nodes and computing reputations. A recovery mechanism is designed to isolate malicious nodes by identifying the new roles of nodes and updating the grid tree. In the experiments, some situations of on-off attacks are simulated and the results are compared with other approaches. The experimental results indicate that our approach can detect malicious nodes effectively and guarantee secure data aggregation with acceptable energy consumption.     

Utility‐driven construction of balanced data routing trees in wireless sensor networks

In wireless sensor networks, achieving load balancing in an energy‐efficient manner to improve the network lifetime as much as possible is still a challenging problem because in such networks, the only energy resource for sensor nodes is their battery supplies. This paper proposes a game theoretical‐based solution in the form of a distributed algorithm for constructing load‐balanced routing trees in wireless sensor networks. In our algorithm, load balancing is realized by adjusting the number of children among parents as much as possible, where child adjustment is considered as a game between the parents and child nodes; parents are considered as cooperative players, and children are considered as selfish players. The gained utility by each node is determined by means of some utility functions defined per role, which themselves determine the behavior of nodes in each role. When the game is over, each node gains the maximum benefit on the basis of its utility function, and the balanced tree is constructed. The proposed method provides additional benefits when in‐network aggregation is applied. Analytical and simulation results are provided, demonstrating that our proposed algorithm outperform two recently proposed benchmarking algorithms [1, 2], in terms of time complexity and communication overhead required for constructing the load‐balanced routing trees. Copyright © 2012 John Wiley & Sons, Ltd.     

传感器网络中节点能量有效均衡的Top-k查询技术

无线传感器网络中top-k查询处理的节点能量高效以及实现各节点的能量消耗均衡,可以有效延长网络的生命周期。该文提出一种基于采样技术和节点空间相关性,来实现节点的能量均衡和高效的查询处理算法,称为能量均衡采样(,)近似top-k算法EBSTopk(,)。首先对传感器网络进行分区处理,利用区域内两两节点间的空间相关性对其建立线性回归预测模型和高斯预测模型;然后根据用户给定的相对误差界和置信水平1-建立节点高相关性预测准则;最后根据上述预测模型和准则,提出基于反复随机采样的能量均衡算法EBSTopk(,)-LR和EBSTopk(,)-MG。实验表明,所提出的EBSTopk(,)算法减少了无线传感器网络中的全局能量消耗,且在多次top-k查询后各节点的能量消耗达到均衡。     

SGDD: self‐managed grid‐based data dissemination protocol for mobile sink in wireless sensor network

The reduction of energy consumption in order to increase network lifetime is one of the most major challenges in the design of wireless sensor networks. During data dissemination, the sensors that are located in the sink's neighborhood are responsible to relay data to the other nodes; hence, their energy is exhausted expeditiously. Therefore, the idea of utilizing mobile sinks can be so advantageous to decrease energy consumption during data dissemination process. In this paper, we propose self‐managed grid‐based data disseminating protocol for mobile sink in wireless sensor networks by using the idea of constructing a virtual grid. In self‐managed grid‐based data disseminating protocol, sink and nodes map their geographical position to a virtual location. In order to increase the performance, we have employed a cell head for each grid cell. Cell heads are selected based on two parameters, centralization and residual energy. Our data dissemination protocol is simple and has low overhead to construct and maintain. Also, we have presented a new method for sink location update, which leads to the least cost in data transfer. Simulation results illustrate that by utilizing hierarchical functionality and determining an optimal size for grid cells, energy consumption is decreased, which leads to increasing network lifetime. Copyright © 2015 John Wiley & Sons, Ltd.     

面向数据相关的传感器网络采样算法

针对某些特定场合无线传感器网络中传感器产生的数据时间和空间上的冗余和高度相关性,提出了一种面向数据相关性及权重的传感器网络采样优化算法DCACW。它基于聚合树结构连接整个网络,在各节点根据样本的相关性和节点权重进行数据融合。仿真实验结果表明,本算法采集的样本覆盖度更广,而且在聚合树中去除了冗余和相关的数据,保证了最终收集的样本差异性较强。     

Communication-efficient implementation of join in sensor networks

A sensor network is a multi-hop wireless network of sensor nodes cooperatively solving a sensing task. Each sensor node generates data items that are readings obtained from one or more sensors on the node. This makes a sensor network similar to a distributed database system. While this view is somewhat traditional, efficient execution of database (SQL) queries in sensor network remains a challenge, due to the unique characteristics of such networks such as limited memory and battery energy on individual nodes, multi-hop communication, unreliable infrastructure, and dynamic topology. Since the nodes are battery powered, the sensor network relies on energy-efficiency (and hence, communication efficiency) for a longer lifetime of the network.In this article, we have addressed the problem of communication-efficient implementation of the SQL “join” operator in sensor networks. In particular, we design an optimal algorithm for implementation of a join operation in dense sensor networks that provably incurs minimum communication cost under some reasonable assumptions. Based on the optimal algorithm, we design a suboptimal heuristic that empirically delivers a near-optimal join implementation strategy and runs much faster than the optimal algorithm. Through extensive simulations on randomly generated sensor networks, we show that our techniques achieve significant energy savings compared to other simple approaches.     

基于网格和遗传算法的移动代理路由算法研究

针对一类基于移动代理的无线传感器网络内移动代理的迁移路由问题,提出了一种基于网格和遗传算法的移动代理迁移路由算法.该方法通过改进的自适应遗传算法获取迁移的基路径信息,再结合网络网格化和路由修复策略来实现路由节点失效时的路由修复,从而有效降低能耗和实现成功迁移.     

Distributed fuzzy approach to unequal clustering and routing algorithm for wireless sensor networks

Due to inherent issue of energy limitation in sensor nodes, the energy conservation is the primary concern for large‐scale wireless sensor networks. Cluster‐based routing has been found to be an effective mechanism to reduce the energy consumption of sensor nodes. In clustered wireless sensor networks, the network is divided into a set of clusters; each cluster has a coordinator, called cluster head (CH). Each node of a cluster transmits its collected information to its CH that in turn aggregates the received information and sends it to the base station directly or via other CHs. In multihop communication, the CHs closer to the base station are burdened with high relay load; as a result, their energy depletes much faster as compared with other CHs. This problem is termed as the hot spot problem. In this paper, a distributed fuzzy logic‐based unequal clustering approach and routing algorithm (DFCR) is proposed to solve this problem. Based on the cluster design, a multihop routing algorithm is also proposed, which is both energy efficient and energy balancing. The simulation results reinforce the efficiency of the proposed DFCR algorithm over the state‐of‐the‐art algorithms, ie, energy‐aware fuzzy approach to unequal clustering, energy‐aware distributed clustering, and energy‐aware routing algorithm, in terms of different performance parameters like energy efficiency and network lifetime.     

A grid based clustering and routing algorithm for solving hot spot problem in wireless sensor networks

Energy conservation of the sensor nodes is the most important issue that has been studied extensively in the design of wireless sensor networks (WSNs). In many applications, the nodes closer to the sink are overburdened with huge traffic load as the data from the entire region are forwarded through them to reach the sink. As a result, their energy gets exhausted quickly and the network is partitioned. This is commonly known as hot spot problem. Moreover, sensor nodes are prone to failure due to several factors such as environmental hazards, battery exhaustion, hardware damage and so on. However, failure of cluster heads (CHs) in a two tire WSN is more perilous. Therefore, apart from energy efficiency, any clustering or routing algorithm has to cope with fault tolerance of CHs. In this paper, we address the hot spot problem and propose grid based clustering and routing algorithms, combinedly called GFTCRA (grid based fault tolerant clustering and routing algorithms) which takes care the failure of the CHs. The algorithms follow distributed approach. We also present a distributed run time management for all member sensor nodes of any cluster in case of failure of their CHs. The routing algorithm is also shown to tolerate the sudden failure of the CHs. The algorithms are tested through simulation with various scenarios of WSN and the simulation results show that the proposed method performs better than two other grid based algorithms in terms of network lifetime, energy consumption and number of dead sensor nodes.     

A Green Clustering Protocol for Mobile Sensor Network Using Particle Swarm Optimization

Energy consumption of sensor nodes is one of the crucial issues in prolonging the lifetime of wireless sensor networks. One of the methods that can improve the utilization of sensor nodes batteries is the clustering method. In this paper, we propose a green clustering protocol for mobile sensor networks using particle swarm optimization (PSO) algorithm. We define a new fitness function that can optimize the energy consumption of the whole network and minimize the relative distance between cluster heads and their respective member nodes. We also take into account the mobility factor when defining the cluster membership, so that the sensor nodes can join the cluster that has the similar mobility pattern. The performance of the proposed protocol is compared with well-known clustering protocols developed for wireless sensor networks such as LEACH (low-energy adaptive clustering hierarchy) and protocols designed for sensor networks with mobile nodes called CM-IR (clustering mobility-invalid round). In addition, we also modify the improved version of LEACH called MLEACH-C, so that it is applicable to the mobile sensor nodes environment. Simulation results demonstrate that the proposed protocol using PSO algorithm can improve the energy consumption of the network, achieve better network lifetime, and increase the data delivered at the base station.     

Towards broadcast redundancy minimization in duty‐cycled wireless sensor networks

Broadcast is an essential operation in wireless sensor networks. Because of the necessity of energy conservation, minimizing the number of transmissions is always a challenging issue in broadcasting scheme design. This paper studies the minimum‐transmission broadcast problem in duty‐cycled wireless sensor networks where each sensor operates under active/dormant cycles. To address the problem, our proposed scheme, Broadcast Redundancy Minimization Scheduling (BRMS), finds a set of forwarding nodes, which minimizes the number of broadcast transmissions. Then, it constructs a forest of sub‐trees based on the relationship between each forwarding node and its corresponding receivers. A broadcast tree is constructed ultimately by connecting all sub‐trees with a minimum number of connectors. Theoretical analysis shows that BRMS obtains a lower approximation ratio as well as time complexity compared with existing schemes. A set of extensive simulations is conducted to evaluate the performance of BRMS. The results reveal that BRMS outperforms others and its solution is close to the lower bound of the problem in terms of the total number of transmissions. Copyright © 2016 John Wiley & Sons, Ltd.     

能耗均衡和可靠的无线传感器网络分簇算法

为了解决热区问题和单点失效问题,提出了一种新的无线传感器网络分簇算法。算法将网络划分为非均匀的栅格,每个栅格的节点分别构成一个簇,根据节点失效概率确定栅格簇首的数目,并由栅格的多个簇首协作完成该栅格节点的数据收集。算法通过调整各个栅格中可参与簇首轮换的节点数目,从长远均衡节点之间的能耗。通过建立包含多个簇首的簇,算法降低了簇成员对单个簇首的依赖性。此外,算法还采取了一些降低能耗的措施。实验结果表明,该算法能够达到较高的能耗均衡程度和数据收集可靠性,并可以延长网络的生命周期。     

Achieving energy‐neutral data transmission by adjusting transmission power for energy‐harvesting wireless sensor networks

Recently, benefiting from rapid development of energy harvesting technologies, the research trend of wireless sensor networks has shifted from the battery‐powered network to the one that can harvest energy from ambient environments. In such networks, a proper use of harvested energy poses plenty of challenges caused by numerous influence factors and complex application environments. Although numerous works have been based on the energy status of sensor nodes, no work refers to the issue of minimizing the overall data transmission cost by adjusting transmission power of nodes in energy‐harvesting wireless sensor networks. In this paper, we consider the optimization problem of deriving the energy‐neutral minimum cost paths between the source nodes and the sink node. By introducing the concept of energy‐neutral operation, we first propose a polynomial‐time optimal algorithm for finding the optimal path from a single source to the sink by adjusting the transmission powers. Based on the work earlier, another polynomial‐time algorithm is further proposed for finding the approximated optimal paths from multiple sources to the sink node. Also, we analyze the network capacity and present a near‐optimal algorithm based on the Ford–Fulkerson algorithm for approaching the maximum flow in the given network. We have validated our algorithms by various numerical results in terms of path capacity, least energy of nodes, energy ratio, and path cost. Simulation results show that the proposed algorithms achieve significant performance enhancements over existing schemes. Copyright © 2016 John Wiley & Sons, Ltd.     

基于空间相关性的事件驱动无线传感器网络分簇算法

分簇算法是传感器网络中减少能量消耗的一种关键技术,它能够增强网络的扩展性和延长网络的生存时间。针对传感器节点数据的空间相关性,该文提出了一种新的基于空间相关性的事件驱动传感器网络分簇算法。算法根据用户要求的误差门限及结合节点数据的空间相关性马尔可夫模型,将事件感知区域划分成虚拟极坐标等价层。每个等价层选取层内当前剩余能量最大的节点作为簇头,网络通过移动代理收集簇头感知信息,该方法减少了传输数据量,有效节省了网络能量。     

Efficient location‐based topology control algorithms for wireless ad hoc and sensor networks

Topology control is an efficient strategy for improving the performance of wireless ad hoc and sensor networks by building network topologies with desirable features. In this process, location information of nodes can be used to improve the performance of a topology control algorithm and also ease its operations. Many location‐based topology control algorithms have been proposed. In this paper, we propose two location‐assisted grid‐based topology control (GBP) algorithms. The design objective of our algorithm is to effectively reduce the number of active nodes required to keep global network connectivity. In grid‐based topology control, a network is divided into equally spaced squares (called grids). We accordingly design cross‐sectional topology control algorithm and diagonal topology control algorithm based on different network parameter settings. The key idea is to build near‐minimal connected dominating set for the network at the grid level. Analytical and simulation results demonstrate that our designed algorithms outperform existing work. Furthermore, the diagonal algorithm outperforms the cross‐sectional algorithm. Copyright © 2016 John Wiley & Sons, Ltd.