Accelerated collection of sensor data by mobility-enabled topology ranks

We study the problem of fast and energy-efficient data collection of sensory data using a mobile sink, in wireless sensor networks in which both the sensors and the sink move. Motivated by relevant applications, we focus on dynamic sensory mobility and heterogeneous sensor placement. Our approach basically suggests to exploit the sensor motion to adaptively propagate information based on local conditions (such as high placement concentrations), so that the sink gradually “learns” the network and accordingly optimizes its motion. Compared to relevant solutions in the state of the art (such as the blind random walk, biased walks, and even optimized deterministic sink mobility), our method significantly reduces latency (the improvement ranges from 40% for uniform placements, to 800% for heterogeneous ones), while also improving the success rate and keeping the energy dissipation at very satisfactory levels.     

An improved ant colony optimization-based approach with mobile sink for wireless sensor networks

Traditional wireless sensor networks (WSNs) with one static sink node suffer from the well-known hot spot problem, that of sensor nodes near the static sink bear more traffic load than outlying nodes. Thus, the overall network lifetime is reduced due to the fact some nodes deplete their energy reserves much faster compared to the rest. Recently, adopting sink mobility has been considered as a good strategy to overcome the hot spot problem. Mobile sink(s) physically move within the network and communicate with selected nodes, such as cluster heads (CHs), to perform direct data collection through short-range communications that requires no routing. Finding an optimal mobility trajectory for the mobile sink is critical in order to achieve energy efficiency. Taking hints from nature, the ant colony optimization (ACO) algorithm has been seen as a good solution to finding an optimal traversal path. Whereas the traditional ACO algorithm will guide ants to take a small step to the next node using current information, over time they will deviate from the target. Likewise, a mobile sink may communicate with selected node for a relatively long time making the traditional ACO algorithm delays not suitable for high real-time WSNs applications. In this paper, we propose an improved ACO algorithm approach for WSNs that use mobile sinks by considering CH distances. In this research, the network is divided into several clusters and each cluster has one CH. While the distance between CHs is considered under the traditional ACO algorithm, the mobile sink node finds an optimal mobility trajectory to communicate with CHs under our improved ACO algorithm. Simulation results show that the proposed algorithm can significantly improve wireless sensor network performance compared to other routing algorithms.     

Fault-resilient sensing in wireless sensor networks

Research on wireless sensor networks (WSNs) has received tremendous attention in the past few years due to their potential applications and advances in the VLSI design. In WSNs with tiny sensors, mobility of a sink may provide an energy efficient way for data dissemination. Having a mobile sink in WSN, however, creates new challenges to routing and sensor distribution modeling in the network. In this paper, based on clustering and routing optimization algorithms, we propose a new scheme called K-means and TSP-based mobility (KAT mobility). After clustering the sensor nodes, the proposed method navigates the mobile sink to traverse through the cluster centers according to the trajectory of an optimized route. The mobile sink then collects the data from sensors at the visited clusters. Simulation results have demonstrated that the proposed scheme can provide not only better energy efficiency as compared to those obtained by conventional methods which assume random waypoint for the mobile sink, but also fault-resilience in case of malfunctions of some sensors due to attacks.     

An enhanced real-time routing protocol with load distribution for mobile wireless sensor networks

Mobile wireless sensor network (MWSN) is a wireless ad hoc network that consists of a very large number of tiny sensor nodes communicating with each other in which sensor nodes are either equipped with motors for active mobility or attached to mobile objects for passive mobility. A real-time routing protocol for MWSN is an exciting area of research because messages in the network are delivered according to their end-to-end deadlines (packet lifetime) while sensor nodes are mobile. This paper proposes an enhanced real-time with load distribution (ERTLD) routing protocol for MWSN which is based on our previous routing protocol RTLD. ERTLD utilized corona mechanism and optimal forwarding metrics to forward the data packet in MWSN. It computes the optimal forwarding node based on RSSI, remaining battery level of sensor nodes and packet delay over one-hop. ERTLD ensures high packet delivery ratio and experiences minimum end-to-end delay in WSN and MWSN compared to baseline routing protocol. In this paper we consider a highly dynamic wireless sensor network system in which the sensor nodes and the base station (sink) are mobile. ERTLD has been successfully studied and verified through simulation experiment.     

用于移动汇聚节点的自适应数据采集策略

移动汇聚节点用于无线传感网络信息采集,可以提高网络能效性,延长网络生命期。研究了四轴飞行器携带 移动汇聚节点,该节点可采集地面无线传感网数据。通过分析汇聚节点空中移动特性,探讨了低功耗无线数据采集 时,移动轨迹、速率和高度与移动汇聚节点能够发送的数据量的之间的理论约束条件。在满足约束条件前提下,提出 基于数据量局部最优化策略,用以控制移动汇聚节点移动路径。在仿真环境中,详尽分析了这种数据采集策略下逗留 时间与移动轨迹、速度和高度等之间的关系,为这类应用莫定了理论基础。     

移动传感器网络实验平台的设计与实现

本文针对无线传感器网络机动能力欠缺、无重部署能力的问题,设计并实现了一种具有机动能力的无线传感网络平台.该平台主要由一个汇聚节点和多个移动节点组成,移动节点和汇聚节点间通过多跳的方式进行数据交换.每个移动节点均具有传感、计算、通讯和机动能力,用户可以根据需要实时地改变节点的部署情况.演示实验结果表明,该平台在摄像头的监控下具有节点重部署的能力.     

An efficient trajectory design for mobile sink in a wireless sensor network

Mobile sink trajectory plays a pivotal role for network coverage, data collection and data dissemination in wireless sensor networks. Considering this, we propose a novel approach for mobile sink trajectory in wireless sensor networks. Our proposed approach is based on Hilbert Space Filling Curve, however, the proposed approach is different from the previous work in a sense that the curve order changes according to node density. In this paper, we investigate the mobile sink trajectory based on Hilbert Curve Order which depends upon the size of the network. Second, we calculate the Hilbert Curve Order based on node density to re-dimension the mobile sink trajectory. Finally, we perform extensive simulations to evaluate the effectiveness of proposed approach in terms of network coverage and scalability. Simulation results confirm that our proposed approach outperforms with size based Hilbert Curve in terms of network coverage, packet delivery ratio and average energy consumption.     

移动传感器网络中基于概率分布的动态的低冗余路由算法

受到节点移动、有限的存储空间及能量等因素的影响,容延迟移动传感器网络在将数据汇聚至Sink过程中伴随着较高的丢包率与数据冗余,传统的确定性路由机制难以应用。对此,利用节点在一定数量时间槽内与Sink点连通的概率分布,提出了一种动态的、分布式的路由算法。该算法充分利用了节点的移动性,使网络在保持低冗余的同时,具有较高的数据送达率。实验结果表明,在节点数多、移动速度快、节点传输距离大的网络中,该算法更具优势。     

Efficient data-forwarding method in delay-tolerant P2P networking for IoT services

These days Internet of Things (IoT), which consists of smart objects such as sensor nodes is the most important technology for providing intelligent services. In the IoT ecosystem, wireless sensor networks deliver collected information from IoT devices to a server via sink nodes, and IoT services are provided by peer-to-peer (P2P) networking between the server and the IoT devices. Particularly, IoT applications with wide service area requires the mobile sink nodes to cover the service area. To employ mobile sink nodes, the network adopts delay-tolerant capability by which delay-tolerant nodes try to transmit data when they connect to the mobile sink node in the application service field. However, if the connection status between a IoT device and a mobile sink node is not good, the efficiency of data forwarding will be decreased. In addition, retransmission in bad connection cause high energy consumption for data transmission. Therefore, data forwarding in the delay-tolerant based services needs to take the connection status into account. The proposed method predicts the connection status using naïve Bayesian classifier and determines whether the delay tolerant node transmits data to the mobile sink node or not. Furthermore, the efficiency of the proposed method was validated through extensive computer simulations.     

基于可预测移动汇聚节点的无线传感网分簇算法研究

在汇聚节点移动可预测情况下,提出一种无线传感网分簇算法。该算法将subsink节点引入到HEED分簇算法中,以较快感知移动路径变化,快速形成分簇拓扑;采用sink节点注册机制,实现汇聚节点移动过程中的信息交互。实例分析表明,该算法能快速形成合理网络拓扑,延长无线传感网的生存期。     

SWER: small world-based efficient routing for wireless sensor networks with mobile sinks

The interest in small-world network has highlighted the applicability of both the graph theory and the scaling theory to the analysis of network systems. In this paper, we introduce a new routing protocol, small world-based efficient routing (SWER), dedicated to supporting sink mobility and small transfers. The method is based on the concept of the small worlds where the addition of a small number of long-range links in highly clustered networks results in significant reduction in the average path length. Based on the characteristic of sensor networks, a cluster-based small world network is presented, and an analytical model is developed to analyze the expected path length. SWER adopts a simple and effective routing strategy to forward data to the mobile sink in a small transfer scene and avoid expensive mechanisms to construct a high quality route. We also study the routing scheme and analyze the expected path length in the case where every node is aware of the existence of p long-range links. In addition, we develop a hierarchical mechanism in which the mobile sink only transmits its location information to the cluster heads when it enters a new cluster. Thus we also avoid expensive cost to flood the location of the mobile sink to the whole network.     

动态传感器网络区域受限的移动sink路径选择研究

针对sink区域受限及节点特征参数的问题,如何规划sink路径选择以满足动态传感器网络高效数据收集及低能耗的要求,提出了一种动态传感器网络区域受限的移动sink路径选择方法。该方法在缓存节点辅助通信模式下,建立sink受限区域图模型。针对不同应用情况,分别讨论了sink移动全局路径信息已知和sink移动局部路径信息已知这两种情况下的最优移动路径。在全局路径信息已知时,采用Vornon单元划分的思想求解总传输能耗和节点平均负载;在局部路径信息已知时,采用启发式策略进行路径寻优,并证明其路径寻优的正确性。最后通过仿真实验与理论计算来验证移动sink最佳路径寻优策略的有效性和可行性。     

Energy efficient secure data collection with path-constrained mobile sink in duty-cycled unattended wireless sensor network

This paper addresses the problem of secure data transmission and balanced energy consumption in an unattended wireless sensor network (UWSN) comprising of multiple static source nodes and a mobile sink in the presence of adversaries. The proposed system comprises of three phases: the identification of data collection points (convex nodes), path planning by the mobile sink, and secure data transmission. An energy-aware convex hull algorithm is used for the identification of data collection points for data transmission to the mobile sink. Data transmission from sensor nodes to the nearest data collection point is performed using multihop communication and from sensor nodes to the mobile sink in a single hop. Data are securely transmitted through an elliptic curve cryptography based ElGamal scheme for message authentication. A data packet is associated with a digital signature. The variation in a digital signature and threshold energy obtained using support vector machine is used to determine the presence of malicious nodes in the network. The performance of the proposed system is evaluated using Cooja simulator by Contiki for various node counts under a static sink and mobile sink, with different threat scenarios. The results indicate that the proposed system is resilient against threats and provides satisfactory performance     

WSN数据收集中移动sink的路径规划和蔟头节点选取问题的综合研究

针对较大规模的无线传感器网络通过多跳传输进行数据收集而引起的能量空洞问题,本文提出了一种基于移动sink的簇头节点数据收集算法（MSRDG）,该算法基于图论原理,在满足时延性的条件下,综合考虑了普通节点到簇头节点路由和移动sink遍历路经选取的问题,构建了一条通过的簇头节点尽可能多的移动轨迹。通过NS-2仿真软件对算法的性能进行评估,结果显示出该算法能减少数据的多跳传输,降低无线传感器网络节点的能量消耗,延长网络寿命。     

Hierarchical role-based data dissemination in wireless sensor networks

Data dissemination from multiple sources to mobile sinks is fundamental and challenging in WSN applications due to limited energy supply of sensor nodes and sink mobility. Previous data dissemination protocols either rely on an energy-consuming coordinate system or build an inefficient backbone. In this paper, we propose a hierarchical role-based data dissemination (HRDD) protocol in wireless sensor networks. In HRDD, a small number of sensor nodes are assigned to serve as cluster heads and agents to form the data dissemination backbone and mitigate unnecessary query forwarding. In addition, HRDD designs an efficient data delivery mechanism that provides shorter paths to accelerate data delivery as well as reduce the number of data transmissions. An adaptive backbone maintenance mechanism is also introduced for low-energy cluster heads and agents to reduce their load, thereby prolonging the network lifetime. The experimental results show that HRDD achieves the longer network lifetime, the shorter delay, and the high success ratio compared to the prior work.     

Decision-aware data suppression in wireless sensor networks for target tracking applications

Target tracking applications of wireless sensor networks (WSNs) may provide a high performance only when a reliable collection of target positions from sensor nodes is ensured. The performance of target tracking in WSNs is affected by transmission delay, failure probability, and nodes energy depletion. These negative factors can be effectively mitigated by decreasing the amount of transmitted data. Thus, the minimization of data transfers from sensor nodes is an important research issue for the development of WSN-based target tracking applications. In this paper, a data suppression approach is proposed for target chasing in WSNs. The aim of the considered target chasing task is to catch a moving target by a mobile sink in the shortest time. According to the introduced approach, a sensor node sends actual target position to the mobile sink only if this information is expected to be useful for minimizing the time in which target will be caught by the sink. The presented method allows sensor nodes to evaluate the usefulness of sensor readings and select those readings that have to be reported to the sink. Experiments were performed in a simulation environment to compare effectiveness of the proposed approach against state-of-the-art methods. Results of the experiments show that the presented suppression method enables a substantial reduction in the amount of transmitted data with no significant negative effect on target chasing time.     

SWER:small world-based efficient routing for wireless sensor networks with mobile sinks

The interest in small-world network has highlighted the applicability of both the graph theory and the scaling theory to the analysis of network systems. In this paper, we introduce a new routing protocol, small world-based efficient routing (SWER), dedicated to supporting sink mobility and small transfers. The method is based on the concept of the small worlds where the addition of a small number of long-range links in highly clustered networks results in significant reduction in the average path length. Based on the characteristic of sensor networks, a cluster-based small world network is presented, and an analytical model is developed to analyze the expected path length. SWER adopts a simple and effective routing strategy to forward data to the mobile sink in a small transfer scene and avoid expensive mechanisms to construct a high quality route. We also study the routing scheme and analyze the expected path length in the case where every node is aware of the existence of p longrange links. In addition, we develop a hierarchical mechanism in which the mobile sink only transmits its location information to the cluster heads when it enters a new cluster. Thus we also avoid expensive cost to flood the location of the mobile sink to the whole network.     

Toward the Optimal Itinerary-Based KNN Query Processing in Mobile Sensor Networks

Current approaches to K Nearest Neighbor (KNN) search in mobile sensor networks require certain kind of indexing support. Creation and maintenance of these index structures, to reflect the network dynamics due to sensor node mobility, may result in long query response time and low battery efficiency, thus limiting their practical use. We propose a maintenance-free, itinerary-based approach called Density-aware Itinerary KNN query processing (DIKNN). The DIKNN divides the search area into multiple cone-shape areas centered at the query point. It then performs a query dissemination and response collection itinerary in each of the cone-shape areas in parallel. The design of the DIKNN scheme takes into account several challenging issues such as the tradeoff between degree of parallelism and network interference on query response time, and the dynamic adjustment of the search radius (in terms of number of hops) according to spatial irregularity or mobility of sensor nodes. This model is validated by extensive simulations. The simulation results show that DIKNN yields substantially better performance and scalability over previous work, both as k increases and as the sensor node mobility increases.     

基于分簇的移动协助无线传感器网络路由协议

提出了一种基于分簇的移动协助（ CMA）无线传感器网络路由协议。在圆形网络中,Sink以恒定速率做圆周运动,网络初始阶段根据应用时延要求和能量消耗确定移动 Sink的运动半径,按照确定的Sink运动轨迹,将网络进行分簇。然后在Sink通信范围内确定一批普通节点作为汇聚点（ RP）,最后Sink对汇聚节点的缓存数据以及其单跳范围内的簇头进行采集。仿真实验结果表明：与现有的几种路由协议相比,CMA在满足时延要求条件下有效地延长了网络生命周期。     

EDVWDD: Event-Driven Virtual Wheel-based Data Dissemination for Mobile Sink-Enabled Wireless Sensor Networks

The Journal of Supercomputing - Despite the several advantages of mobile sink-enabled wireless sensor networks, the data dissemination to mobile sink is challenging for resource-constrained sensor...