无线传感器网络能耗分析与策略研究

无线传感器网络技术得到了广泛应用,但是该技术一直受能量的制约,因此能量始终是无线传感器网络的核心问题。通过对传感器节点结构与网络体系的分析,得出了传感器网络的能耗特性。为了延长无线传感器网络的生命周期,对传感器节点工作能耗与传感网络能耗做了具体研究,再从低功耗节点设计、网络协议及环境中能量补给三个方面总结出了一套有效的节能策略。     

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.     

Performance analysis of relative location estimation for multihop wireless sensor networks

In this paper, we present new analytical, simulated, and experimental results on the performance of relative location estimation in multihop wireless sensor networks. With relative location, node locations are estimated based on the collection of peer-to-peer ranges between nodes and their neighbors using a priori knowledge of the location of a small subset of nodes, called reference nodes. This paper establishes that when applying relative location to multihop networks the resulting location accuracy has a fundamental upper bound that is determined by such system parameters as the number of hops and the number of links to the reference nodes. This is in contrast to the case of single-hop or fully connected systems where increasing the node density results in continuously increasing location accuracy. More specifically, in multihop networks for a fixed number of hops, as sensor nodes are added to the network the overall location accuracy improves converging toward a fixed asymptotic value that is determined by the total number of links to the reference nodes, whereas for a fixed number of links to the reference nodes, the location accuracy of a node decreases the greater the number of hops from the reference nodes. Analytical expressions are derived from one-dimensional networks for these fundamental relationships that are also validated in two-dimensional and three-dimensional networks with simulation and UWB measurement results.     

无线传感网络中基于蚁群的路由算法

In the wireless sensor networks, high efficient data routing for the limited energy resource networks is an important issue. By introducing Ant-colony algorithm, this paper proposes the wireless sensor network routing algorithm based on LEACH. During the construction of sensor network clusters, to avoid the node premature death because of the energy consumption, only the nodes whose residual energy is higher than the average energy can be chosen as the cluster heads. The method of repeated division is used to divide the clusters in sensor networks so that the numbers of the nodes in each cluster are balanced. The basic thought of ant-colony algorithm is adopted to realize the data routing between the cluster heads and sink nodes, and the maintenance of routing. The analysis and simulation showed that the proposed routing protocol not only can reduce the energy consumption, balance the energy consumption between nodes, but also prolong the network lifetime.     

An Automatic Presence Service for Low Duty-Cycled Mobile Sensor Networks

We consider providing presence service for duty-cycled wireless sensor networks through a multihop approach. The presence service is to ensure automatic network monitoring by which each node would know whether the sink node is reachable or not. Towards providing such presence service, we tackle three problems: 1) efficient neighbor discovery due to not-always-awake nature of duty-cycling and the mobile environment, 2) light presence message passing from the sink node to all reachable nodes given broadcasting is expensive and difficult in an embedded duty-cycling network, and 3) automatic network monitoring if there is node failure and network partition. In our protocol, in order to save power consumption, an online node which is reachable from the sink node only book-keeps the broadcast schedule of its parent in a breadth-first-search spanning tree in order to trace the online status all along. The offline node which is not reachable from the sink node stays awake periodically based on quorum-based wakeup scheduling, and probes the beacons which may come from online nodes. The presence protocol can automatically detect link failure or network partition, and it can also automatically recover online status for each sensor node if there is a path to the sink node, which is significant for applications that are sensitive to end-to-end latency constraints. The presence protocol proposed is implemented through a layered approach so that it is independent from any specific MAC and routing protocols. We make extensive simulations in order to validate the energy efficiency and reliability of our design.     

Medium access control with coordinated adaptive sleeping for wireless sensor networks

This paper proposes S-MAC, a medium access control (MAC) protocol designed for wireless sensor networks. Wireless sensor networks use battery-operated computing and sensing devices. A network of these devices will collaborate for a common application such as environmental monitoring. We expect sensor networks to be deployed in an ad hoc fashion, with nodes remaining largely inactive for long time, but becoming suddenly active when something is detected. These characteristics of sensor networks and applications motivate a MAC that is different from traditional wireless MACs such as IEEE 802.11 in several ways: energy conservation and self-configuration are primary goals, while per-node fairness and latency are less important. S-MAC uses a few novel techniques to reduce energy consumption and support self-configuration. It enables low-duty-cycle operation in a multihop network. Nodes form virtual clusters based on common sleep schedules to reduce control overhead and enable traffic-adaptive wake-up. S-MAC uses in-channel signaling to avoid overhearing unnecessary traffic. Finally, S-MAC applies message passing to reduce contention latency for applications that require in-network data processing. The paper presents measurement results of S-MAC performance on a sample sensor node, the UC Berkeley Mote, and reveals fundamental tradeoffs on energy, latency and throughput. Results show that S-MAC obtains significant energy savings compared with an 802.11-like MAC without sleeping.     

Network Lifetime Maximization for Estimation in Multihop Wireless Sensor Networks

We consider the distributed estimation by a network consisting of a fusion center and a set of sensor nodes, where the goal is to maximize the network lifetime, defined as the estimation task cycles accomplished before the network becomes nonfunctional. In energy-limited wireless sensor networks, both local quantization and multihop transmission are essential to save transmission energy and thus prolong the network lifetime. The network lifetime optimization problem includes three components: i) optimizing source coding at each sensor node, ii) optimizing source throughput of each sensor node, and iii) optimizing multihop routing path. Fortunately, source coding optimization can be decoupled from source throughput and multihop routing path optimization, and is solved by introducing a concept of equivalent 1-bit MSE function. Based on the optimal source coding, the source throughput and multihop routing path optimization is formulated as a linear programming (LP) problem, which suggests a new notion of character-based routing. The proposed algorithm is optimal and the simulation results show that a significant gain is achieved by the proposed algorithm compared with heuristic methods.     

基于联合感知模型的无线传感器网络连通性覆盖协议

本文研究在没有节点位置信息的情况下,如何有效地保证节点采用联合感知模型且节点通信范围多级可调的无线传感器网络的覆盖质量和连通性.给出了在节点随机部署方式下,网络覆盖质量和网络连通性与工作节点个数、监测区域面积和节点性能参数的关系;设计了一个选取最少工作节点保证网络覆盖质量和网络连通性的调度控制算法(SCA),该算法力求...     

A new load balancing and data collection algorithm for energy saving in wireless sensor networks

Data gathering is a major function of many applications in wireless sensor networks. The most important issue in designing a data gathering algorithm is how to save energy of sensor nodes while meeting the requirements of special applications or users. Wireless sensor networks are characterized by centralized data gathering, multi-hop communication and many to one traffic pattern. These three characteristics can lead to severe packet collision, network congestion and packet loss, and even result in hot-spots of energy consumption thus causing premature death of sensor nodes and entire network. In this paper, we propose a load balance data gathering algorithm that classifies sensor nodes into different layers according to their distance to sink node and furthermore, divides the sense zone into several clusters. Routing trees are established between sensor node and sink depending on the energy metric and communication cost. For saving energy consumption, the target of data aggregation scheme is adopted as well. Analysis and simulation results show that the algorithm we proposed provides more uniform energy consumption among sensor nodes and can prolong the lifetime of sensor networks.     

An optimised fuzzy clustering for wireless sensor networks

Minimising energy consumption has always been an issue of crucial importance in sensor networks. Most of the energy is consumed in data transmission from sensor nodes to the base station due to the long distance of nodes from the base station. In the recent past, a number of researchers have proposed that clustering is an efficient way of reducing the energy consumption during data transmission and enhancing the lifetime of wireless sensor networks. Many algorithms have been already proposed for cluster head selection. In this work, we analyse and compare the lifetime of the network with three different fuzzy-based approaches of cluster head selection. The three strong parameters which play an important role in lifetime enhancement – energy, centrality and node density – are considered for cluster head selection in our proposed fuzzy approaches. In the first approach, energy and centrality are considered simultaneously in a fuzzy system to select the cluster heads. In the second approach, energy and node density have been taken in a fuzzy system to select the cluster heads. In the third approach, node density and centrality are considered simultaneously by a fuzzy system to select the cluster heads. Simulation results of these fuzzy logic-based approaches show that all the three approaches are superior to the Low-Energy Adaptive Clustering Hierarchy (LEACH). Simulation results also show that the energy-centrality-based fuzzy clustering scheme gives best performance among all the three fuzzy-based algorithms and it enhances the lifetime of wireless sensor networks by a significant amount.     

Relay characteristic impact on energy consumption in heterogeneous sensor network

Indoor heterogeneous wireless sensor networks are considered in this paper. We analyze the power consumption for multihop communications with non-regenerative relays. Since sensor nodes are battery operated, energy consumption is a crucial issue. We determine the optimal relay gains and transmitted power that minimize the dissipated power for a given quality of service in a narrow band fading channel. Our work includes two main contributions: firstly, we study the energy consumption taking into account hardware aspects, especially the relays’ efficiency. In an AWGN channel, carefully analyzing the energy gain as a function of the position, we show that relay characteristics have an important impact on the multihop link consumption budget. We then use a Rice channel model based on simulations and further study the hardware impact on energy saving.     

大规模输电线路状态监测传感器网络的周期性低功耗通信技术方案

为了实现输电线路监测的功耗低、寿命长、绿色发展的目的，提出大规模输电线路状态监测传感器网络周期性低功耗通信技术方案。依据网络中传感器网络组网特征以及节点运行状态转换特点，设置睡眠定时器，以周期性运行方式使传感器网络通信节点在初始化、睡眠、激活状态间转换，通信节点在输电线路状态监测数据无传递需求时进入睡眠状态，节省通信功耗；传感器网络汇聚（sink）节点利用梯度创建上行路由，通过源路由的方式创建下行路由，以跳数和剩余能量为依据进行上、下行路由数据分组传递，降低节点功耗，延长通信运行时间。实验显示，大规模输电线路状态监测传感器网络应用该技术方案后，通信功耗明显降低，运行时间明显延长，且不会影响监测传感器网络的数据传输性能，延长了监测传感器网络的使用寿命。     

基于发布/订阅模型的WSN设计

为降低通信频率对节点能耗的影响同时提高大规模节点下传感器网络的连通率,本文设计了一种以发布/订阅模型作为应用层数据交互方式的无线传感器网络。该网络利用6LoWPAN技术实现组网,并以Contiki操作系统为平台完成了基于发布/订阅模型的MQTT-S应用层协议设计。测试结果表明,该设计能够有效降低节点的通信流量,实现对节点功耗以及网络通信优化,并能与互联网实现无缝连接减少开发成本,对大规模传感器网络的设计与应用具有重要意义。     

Optimal load balanced clustering in homogeneous wireless sensor networks

Balancing the load among sensor nodes is a major challenge for the long run operation of wireless sensor networks. When a sensor node becomes overloaded, the likelihood of higher latency, energy loss, and congestion becomes high. In this paper, we propose an optimal load balanced clustering for hierarchical cluster‐based wireless sensor networks. We formulate the network design problem as mixed‐integer linear programming. Our contribution is 3‐fold: First, we propose an energy aware cluster head selection model for optimal cluster head selection. Then we propose a delay and energy‐aware routing model for optimal inter‐cluster communication. Finally, we propose an equal traffic for energy efficient clustering for optimal load balanced clustering. We consider the worst case scenario, where all nodes have the same capability and where there are no ways to use mobile sinks or add some powerful nodes as gateways. Thus, our models perform load balancing and maximize network lifetime with no need for special node capabilities such as mobility or heterogeneity or pre‐deployment, which would greatly simplify the problem. We show that the proposed models not only increase network lifetime but also minimize latency between sensor nodes. Numerical results show that energy consumption can be effectively balanced among sensor nodes, and stability period can be greatly extended using our models.     

A Two-Layer Key Establishment Scheme for Wireless Sensor Networks

In a large scale sensor network, it is infeasible to assign a unique Transport Layer Key (TLK) for each pair of nodes to provide the end-to-end security due to the huge memory cost per node. Thus, conventional key establishment schemes follow a key predistribution approach to establish a Link Layer Key (LLK) infrastructure between neighboring nodes and rely on multihop paths to provide the end-to-end security. Their drawbacks include vulnerability to the node compromise attack, large memory cost, and energy inefficiency in the key establishment between neighboring nodes. In this paper, we propose a novel key establishment scheme, called LAKE, for sensor networks. LAKE uses a t-degree trivariate symmetric polynomial to facilitate the establishment of both TLKs and LLKs between sensor nodes in a two-dimensional space, where each node can calculate direct TLKs and LLKs with some logically neighboring nodes and rely on those nodes to negotiate indirect TLKs and LLKs with other nodes. Any two end nodes can negotiate a TLK on demand directly or with the help of only one intermediate node, which can be determined in advance. As for the LLK establishment, LAKE is more secure under the node compromise attack with much less memory cost than conventional solutions. Due to the location-based deployment, LAKE is also energy efficient in that each node has direct LLKs with most neighbors without spending too much energy on the establishment of indirect LLKs with neighbors through multihop routing.     

A Pre-Determined Nodes Deployment Strategy of Two-Tiered Wireless Sensor Networks Based on Minimizing Cost

Nodes deployment is a fundamental factor in determining the connectivity, coverage, lifetime and cost of wireless sensor networks. In this paper, a two-tiered wireless sensor networks consisting of sensor clusters and a base station is considered. Within a sensor cluster, there are many sensor nodes and a relay node. We focus on the deployment strategy for sensor nodes and relay nodes to minimize cost under some constraints. Several means are used. The regular hexagonal cell architecture is employed to build networks. Based on the analysis of energy consumption of sensors and cost of network, an integer programming model is presented to minimize the cost. By the model, number of layers of sensor cluster is determined. In order to balance the energy consumption of sensors on the identical layer, a uniform load routing algorithm is used. The numerical analysis and simulation results show that the waste of energy and cost of wireless sensor networks can be effectively reduced by using the strategy.     

一种无线传感器网络的能耗平衡覆盖模型

针对无线传感器网络节点能量有限、最小覆盖方法能耗不均衡的问题,该文提出了一种能耗平衡的连通覆盖模型,并对模型进行了分析与仿真。模型利用Voronoi划分和Delaunay三角剖分对传感器网络进行分割,判别重复覆盖目标区域的冗余传感器节点,采用节点到sink点的跳数对节点分层,进而提出选择休眠节点的方法。仿真结果表明,由模型建立的非最小连通覆盖集所导出的无线传感器网络,能够平衡节点能耗、使用优化路由、减弱路由关键点的影响。     

End-to-End Energy–Bandwidth Tradeoff in Multihop Wireless Networks

In this paper, energy-constrained wireless multihop networks with a single source-destination pair are considered. A network model that incorporates both the energy radiated by the transmitter and the energy consumed by the circuits that process the received signals is proposed. The rate of communication is the number of information bits transmitted (end-to-end) per coded symbol transmitted by any node in the network that is forwarding the data. The tradeoff between the total energy consumption and the end-to-end rate of communication is analyzed. The performance (either energy or rate) depends on the transmission strategy of each node, the location of the relay nodes, and the data rate used by each node. Communication strategies include the rate of transmission on each link, the scheduling of links, and the power used for each link. Strategies that minimize the total energy consumption for a given rate are found. Two communication strategies that capture the inherent constraints of some practical networks are also considered and compared with the optimum strategies. In the case of equispaced relays, analytical results for the tradeoff between the energy and the end-to-end data rate are provided. The minimum energy over all possible data rates is also obtained. Low rates incur a significant penalty because the receiver is on for a long time period while high rates require high transmission energy. At high rates routes with fewer hops minimize the energy consumption while at lower rates more hops minimize the energy consumption.      

DUCR: Distributed unequal cluster‐based routing algorithm for heterogeneous wireless sensor networks

Designing energy efficient communication protocols for wireless sensor networks (WSNs) to conserve the sensors' energy is one of the prime concerns. Clustering in WSNs significantly reduces the energy consumption in which the nodes are organized in clusters, each having a cluster head (CH). The CHs collect data from their cluster members and transmit it to the base station via a single or multihop communication. The main issue in such mechanism is how to associate the nodes to CHs and how to route the data of CHs so that the overall load on CHs are balanced. Since the sensor nodes operate autonomously, the methods designed for WSNs should be of distributed nature, i.e., each node should run it using its local information only. Considering these issues, we propose a distributed multiobjective‐based clustering method to assign a sensor node to appropriate CH so that the load is balanced. We also propose an energy‐efficient routing algorithm to balance the relay load among the CHs. In case any CH dies, we propose a recovery strategy for its cluster members. All our proposed methods are completely distributed in nature. Simulation results demonstrate the efficiency of the proposed algorithm in terms of energy consumption and hence prolonging the network lifetime. We compare the performance of the proposed algorithm with some existing algorithms in terms of number of alive nodes, network lifetime, energy efficiency, and energy population.     

Self-Recommendation Mechanism in Trust Calculation Among Nodes in WSN

This paper proposes a node self-recommendation mechanism which is effective in trust calculation model in wireless sensor networks (WSNs). The mechanism has little practical sense to cable and wireless network among which nodes’ resources, especially energy, are almost unlimited; furthermore it may bring some security risk to networks on the contrary. But as to WSNs where nodes’ resources are strictly limited, a node can express its intension of participating communication to its neighbors by using the mechanism according to its current running state and predefined strategies. This mechanism is useful to save nodes’ energy, balance network load and prolong network lifetime ultimately. The paper focuses on self-recommendation value expression, calculation and synthesis method. Application method of the mechanism is also discussed. Simulation results show that using trust calculation model cooperatively with self-recommendation mechanism can protect low energy nodes effectively and balance energy consumption among adjacent nodes without weakening malicious node identification function of the trust model.