Number Of Mobile Sensor Nodes Research Articles

An Area Coverage Scheme Based on Fuzzy Logic and Shuffled Frog-Leaping Algorithm (SFLA) in Heterogeneous Wireless Sensor Networks

Coverage is a fundamental issue in wireless sensor networks (WSNs). It plays a important role in network efficiency and performance. When sensor nodes are randomly scattered in the network environment, an ON/OFF scheduling mechanism can be designed for these nodes to ensure network coverage and increase the network lifetime. In this paper, we propose an appropriate and optimal area coverage method. The proposed area coverage scheme includes four phases: (1) Calculating the overlap between the sensing ranges of sensor nodes in the network. In this phase, we present a novel, distributed, and efficient method based on the digital matrix so that each sensor node can estimate the overlap between its sensing range and other neighboring nodes. (2) Designing a fuzzy scheduling mechanism. In this phase, an ON/OFF scheduling mechanism is designed using fuzzy logic. In this fuzzy system, if a sensor node has a high energy level, a low distance to the base station, and a low overlap between its sensing range and other neighboring nodes, then this node will be in the ON state for more time. (3) Predicting the node replacement time. In this phase, we seek to provide a suitable method to estimate the death time of sensor nodes and prevent possible holes in the network, and thus the data transmission process is not disturbed. (4) Reconstructing and covering the holes created in the network. In this phase, the goal is to find the best replacement strategy of mobile nodes to maximize the coverage rate and minimize the number of mobile sensor nodes used for covering the hole. For this purpose, we apply the shuffled frog-leaping algorithm (SFLA) and propose an appropriate multi-objective fitness function. To evaluate the performance of the proposed scheme, we simulate it using NS2 simulator and compare our scheme with three methods, including CCM-RL, CCA, and PCLA. The simulation results show that our proposed scheme outperformed the other methods in terms of the average number of active sensor nodes, coverage rate, energy consumption, and network lifetime.

Study of Proactive Routing Protocol in Wildfire Detection Using Mobile Sensor Networks

ABSTRACT Mobile sensor networks include different routing protocols. The performance of these routing protocols differs in terms of transmitting and receiving the packets, where it depends on the architecture of each routing protocol. However, despite there are many protocols that have been proposed, but they have not implemented broadly in disasters, where there is a need to study the routing protocols in disasters such as forest fire detection. Therefore, this paper is present a proactive routing protocol called Optimized Link State Routing Protocol (OLSR). This protocol has implemented in the detection of forest fire based on a different number of mobile sensor nodes in the range of 10-50 nodes with an increment step of 10 nodes. Furthermore, the performance of the OLSR protocol is evaluated in terms of Packet Delivery Ratio (PDR), End-to-End Delay (E2E Delay), energy consumption, and routing overhead. The performance of the OLSR protocol shows encouraging results in the detection of forest fire.

AOA-Based Three-Dimensional Multi-Target Localization in Industrial WSNs for LOS Conditions.

High-precision and fast relative positioning of a large number of mobile sensor nodes (MSNs) is crucial for smart industrial wireless sensor networks (SIWSNs). However, positioning multiple targets simultaneously in three-dimensional (3D) space has been less explored. In this paper, we propose a new approach, called Angle-of-Arrival (AOA) based Three-dimensional Multi-target Localization (ATML). The approach utilizes two anchor nodes (ANs) with antenna arrays to receive the spread spectrum signals broadcast by MSNs. We design a multi-target single-input-multiple-output (MT-SIMO) signal transmission scheme and a simple iterative maximum likelihood estimator (MLE) to estimate the 2D AOAs of multiple MSNs simultaneously. We further adopt the skew line theorem of 3D geometry to mitigate the AOA estimation errors in determining locations. We have conducted extensive simulations and also developed a testbed of the proposed ATML. The numerical and field experiment results have verified that the proposed ATML can locate multiple MSNs simultaneously with high accuracy and efficiency by exploiting the spread spectrum gain and antenna array gain. The ATML scheme does not require extra hardware or synchronization among nodes, and has good capability in mitigating interference and multipath effect in complicated industrial environments.

An analysis of mobility management for mobile sensor nodes in MWSN

Mobile wireless sensor networks (MWSN) are composed of a large number of mobile sensor nodes, which are used to collect data. MWSN have been widely applied in a variety of harsh environments, so mobile sensor nodes are often at risk of damage. How to manage mobile sensor nodes is an important issue. In this paper, we analyse different mobility management schemes proposed in some typical research literature and classify these schemes by using three features: the collaboration between mobile sensor nodes, routing and deployment in MWSN. We specify advantages and disadvantages of the proposed schemes, compare different key parameters of MSWN respectively, including energy efficiency, data delay, cost and lifetime, etc. Finally, we discuss existing problems of MWSN management and give some helpful suggestions in this area.

Achieving location error tolerant barrier coverage for wireless sensor networks

Barrier coverage is a critical issue in wireless sensor networks deployed in security applications (e.g., border protection), whose performance strongly depends on the locations of sensor nodes. Existing works on barrier coverage typically assume that sensor nodes have accurate location information, which is not reasonable or practical for many real sensor networks. In this paper, we study the barrier coverage problem when sensor nodes have location errors and deploy mobile sensor nodes to improve barrier coverage if the network is not barrier-covered after initial deployment. We analyze the effects of location errors for barrier coverage and propose a fault-tolerant weighted barrier graph to model the barrier coverage formation problem. Based on the graph, we prove that the minimum number of mobile sensor nodes needed to achieve barrier coverage with a guarantee is the length of the shortest path on the graph. Furthermore, we improve the computational efficiency of the fault-tolerant barrier coverage formation algorithm by removing unnecessary edges on the graph. Experimental results validate the correctness of our analysis and the proposed algorithms.

Approximation algorithms for sweep coverage in wireless sensor networks

Periodic monitoring is sufficient for sweep coverage with a small number of mobile sensor nodes, whereas a continuous monitoring with static sensor nodes is required for the coverage problem in wireless sensor networks. Finding the minimum number of mobile sensor nodes with a uniform speed to guarantee sweep coverage is NP-hard and it cannot be approximated within a factor of 2 (Li et al., 2011). In this paper we have proposed a 2-approximation algorithm for solving the sweep coverage for a given set of points of interest (PoIs). The best known approximation factor is 3 for this problem (Li et al., 2011). Modification of the algorithm is also proposed for extending lifetime of the mobile sensors, sweep coverage in the presence of obstacles and failure of mobile sensors. When all PoIs are static sensor nodes, we have proposed a distributed approximation algorithm with approximation ratio 2, where the static sensor nodes compute the number of mobile sensor nodes and their positions. We have introduced sweep coverage for a given area of interest (AoI) and proved that the problem is NP-complete. A 22-approximation algorithm is designed in order to solve the problem for a square region. An improvement over the approximation factor is designed for any rectangular region. Based on our simulation study we have shown that less number mobile sensor nodes are required for our point sweep coverage algorithm compared to the algorithm proposed in Du et al. (2010).

Data Gathering Using Mobile Agents for Reducing Traffic in Dense Mobile Wireless Sensor Networks

Recently, there has been increasing interest in Mobile Wireless Sensor Networks (MWSNs) that are constructed by mobile sensor nodes held by ordinary people, and it has led to a new concept called urban sensing. In such MWSNs, mobile sensor nodes densely exist, and thus, there are basically many sensor nodes that can sense a geographical point in the entire sensing area. To reduce the communication cost for gathering sensor data, it is desirable to gather the sensor data from the minimum number of mobile sensor nodes which are necessary to guarantee the sensing coverage or the quality of services. In this paper, to achieve this, we propose a data gathering method using mobile agents in dense MWSNs. The proposed method guarantees the sensing coverage of the entire area using mobile agents that autonomously perform sensing operations, transmit sensor data, and move between sensor nodes. By gathering only sensor data generated by sensor nodes where mobile agents are running, our proposed method can achieve efficient gathering of sensor data.

Data gathering using mobile agents for reducing traffic in dense mobile wireless sensor networks

Recently, there has been increasing interest in Mobile Wireless Sensor Networks MWSNs that are constructed by mobile sensor nodes held by ordinary people, and it has led to a new concept called urban sensing. In such MWSNs, mobile sensor nodes densely exist, and thus, there are basically many sensor nodes that can sense a geographical point in the entire sensing area. To reduce the communication cost for gathering sensor data, it is desirable to gather the sensor data from the minimum number of mobile sensor nodes which are necessary to guarantee the sensing coverage or the quality of services. In this paper, to achieve this, we propose a data gathering method using mobile agents in dense MWSNs. The proposed method guarantees the sensing coverage of the entire area using mobile agents that autonomously perform sensing operations, transmit sensor data, and move between sensor nodes. By gathering only sensor data generated by sensor nodes where mobile agents are running, our proposed method can achieve efficient gathering of sensor data.

MSNS: mobile sensor network simulator for area coverage and obstacle avoidance based on GML

Abstract A mobile sensor network is a distributed collection of sensors, each of which has sensing, computation, communication, and locomotion capabilities. In particular, locomotion facilitates the ability to self-deployment. In such a network of self-deployable mobile sensors, it is difficult to evaluate the effectiveness of mobile sensor network deployment in a given target area because we cannot predict the coverage rate for the target area. The coverage rate will be changed due to the number of sensor required in the target area, connectivity degree to be maintained and unknown obstacles. In this article, we develop mobile sensor network simulator (MSNS) in order to visualize (1) coverage secured by mobile sensors and (2) avoidance of obstacle objects (building, road and wall, and so on) on the real map drawn by GML (Geography Markup Language). From a user, MSNS receives the number of mobile sensor nodes, connectivity degree, sensor node's sensing range, communication range, and supersonic wave range. And then it visualizes the location information of sensor nodes, connectivity degree, and sensing coverage, all of which change with simulation time. Thereby we can estimate how many nodes are required in a given target area, and also calculate coverage rate of the target area in advance to the real deployment of mobile sensors.

AOMDV의 특성과 진동 센서를 적용한 이동성과 연결성이 개선된 WSN용 LEACH 프로토콜 연구

As the growth of ubiquitous services, various types of ad hoc networks have emerged. In particular, wireless sensor networks (WSN) and mobile ad hoc networks (MANET) are widely known ad hoc networks, but there are also other kinds of wireless ad hoc networks in which the characteristics of the aforementioned two network types are mixed together. This paper proposes a variant of the Low Energy Adaptive Cluster Hierarchy (LEACH) routing protocol modified to be suitable in such a combined network environment. That is, the proposed routing protocol provides node detection and route discovery/maintenance in a network with a large number of mobile sensor nodes, while preserving node mobility, network connectivity, and energy efficiency. The proposed routing protocol is implemented with a multi-hop multi-path algorithm, a topology reconfiguration technique using node movement estimation and vibration sensors, and an efficient path selection and data transmission technique for a great many moving nodes. In the experiments, the performance of the proposed protocol is demonstrated by comparing it to the conventional LEACH protocol.

A grid-based coverage approach for target tracking in hybrid sensor networks

Most existing work on the coverage problem of wireless sensor networks focuses on improving the coverage of the whole sensing field. In target tracking, the interested coverage area is the emerging region of a motorized target, not the whole sensing field. As the motorized target moves, the emerging region is also dynamically changed. In this paper, we propose a grid-based and distributed approach for providing large coverage for a motorized target in a hybrid sensor network. The large coverage is achieved by moving mobile sensor nodes in the network. To minimize total movement cost, the proposed approach needs to solve the following problems: the minimum number of mobile sensor nodes used for healing coverage holes and the best matching between mobile sensor nodes and coverage holes. In the proposed approach, the above two problems are first transformed into the modified circle covering and minimum cost flow problems, respectively. Then, two polynomial-time algorithms are presented to efficiently solve these two modified graph problems, respectively. Finally, we perform simulation experiments to show the effectiveness of proposed approach in providing the coverage for a motorized target in a hybrid sensor network.