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Wireless sensor network technologies let us view and access large parts of the physical world from cyberspace via sensor monitoring. The three theme features in this issue address some of the challenges inherent to developing and ...
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Wireless sensor network technologies let us view and access large parts of the physical world from cyberspace via sensor monitoring. The three theme features in this issue address some of the challenges inherent to developing and fielding wireless sensor networks.
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Wireless sensor networks (WSNs) are one of the most promising technologies and have immense potential in both the military and civil field. WSNs offer a range of challenges for scientists and engineers of today. The biggest challe...
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Wireless sensor networks (WSNs) are one of the most promising technologies and have immense potential in both the military and civil field. WSNs offer a range of challenges for scientists and engineers of today. The biggest challenge among all is the energy constraint of these networks. In this context, various schemes have been presented in order to improve the life time of these networks and to overcome the energy constraint. One of the effective schemes is based on clustering of sensor nodes within a network in order to improve the network life time and decrease communication latency. Clustering algorithms are believed to be the best for wireless sensor networks because they work on the principle of divide and conquer. This paper includes a brief survey of various existing clustering algorithms and present a new clustering algorithm based on nondetermistic finite automata which further divides the communication between cluster heads into multihop by using a few nodes from each cluster. Performance studies indicate that the proposed algorithm is more efficient in terms of energy consumption and network connectivity.
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Industrial wireless sensor networks adopt a hierarchical structure with large numbers of sensors and routers. Time Division Multiple Access (TDMA) is regarded as an efficient method to reduce the probability of confliction. In the...
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Industrial wireless sensor networks adopt a hierarchical structure with large numbers of sensors and routers. Time Division Multiple Access (TDMA) is regarded as an efficient method to reduce the probability of confliction. In the intra-cluster part, the random color selection method is effective in reducing the retry times in an application. In the inter-cluster part, a quick assign algorithm and a dynamic maximum link algorithm are proposed to meet the quick networking or minimum frame size requirements. In the simulation, the dynamic maximum link algorithm produces higher reductions in the frame length than the quick assign algorithm. When the number of routers is 140, the total number of time slots is reduced by 25%. However, the first algorithm needs more control messages, and the average difference in the number of control messages is 3 410. Consequently, the dynamic maximum link algorithm is utilized for adjusting the link schedule to the minimum delay with a relatively high throughput rate, and the quick assign algorithm is utilized for speeding up the networking process.
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Time synchronization in wireless sensor networks (WSNs) is a topic that has been attracting the research community in the last decade. Most performance evaluations of the proposed solutions have been limited to theoretical analysi...
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Time synchronization in wireless sensor networks (WSNs) is a topic that has been attracting the research community in the last decade. Most performance evaluations of the proposed solutions have been limited to theoretical analysis and simulation. They consequently ignored several practical aspects, e.g., packet handling jitters, clock drifting, packet loss, and mote limitations, which affect real implementation on sensor motes. Authors of some pragmatic solutions followed empirical approaches for the evaluation, where the proposed solutions have been implemented on real motes and evaluated in testbed experiments. This paper gives an insight on issues related to the implementation of synchronization protocols in WSN. The challenges related to WSN environment are presented; the importance of real implementation and testbed evaluation are motivated by some experiments we conducted. The most relevant implementations of the literature are then reviewed, discussed, and qualitatively compared. While there are several survey papers that present and compare the protocols from the conception perspectives, as well as others that deal with mathematical and signal processing issues of the estimators, a survey on practical aspects related to the implementation is missing. To our knowledge, this paper is the first one that takes into account the practical aspect of existing solutions.
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In a hospital health care monitoring system it is necessary to constantly monitor the patient's physiological parameters. For example a pregnant woman parameters such as blood pressure (BP) and heart rate of the woman and heart ra...
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In a hospital health care monitoring system it is necessary to constantly monitor the patient's physiological parameters. For example a pregnant woman parameters such as blood pressure (BP) and heart rate of the woman and heart rate and movements of fetal to control their health condition. This paper presents a monitoring system that has the capability to monitor physiological parameters from multiple patient bodies. In the proposed system, a coordinator node has attached on patient body to collect all the signals from the wireless sensors and sends them to the base station. The attached sensors on patient's body form a wireless body sensor network (WBSN) and they are able to sense the heart rate, blood pressure and so on. This system can detect the abnormal conditions, issue an alarm to the patient and send a SMS/E-mail to the physician. Also, the proposed system consists of several wireless relay nodes which are responsible for relaying the data sent by the coordinator node and forward them to the base station. The main advantage of this system in comparison to previous systems is to reduce the energy consumption to prolong the network lifetime, speed up and extend the communication coverage to increase the freedom for enhance patient quality of life. We have developed this system in multi-patient architecture for hospital healthcare and compared it with the other existing networks based on multi-hop relay node in terms of coverage, energy consumption and speed.
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Wireless Sensor Networks (WSNs) have paved the way for a new horizon of monitoring and gathering information. One of the most decisive criteria for smooth operation of WSNs is the limited energy supply of the sensor nodes. Numerou...
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Wireless Sensor Networks (WSNs) have paved the way for a new horizon of monitoring and gathering information. One of the most decisive criteria for smooth operation of WSNs is the limited energy supply of the sensor nodes. Numerous elegant energy-efficient routing protocols have been proposed in the literature for solving this problem, e.g. LEACH [1], PEGASIS [2], Hierarchical PEGASIS [3], LEFC [4]. But these protocols seem to suffer from transmission overhead. In this paper we propose Co-Axial Fixed Cluster (CFC), a new energy-efficient hierarchical routing protocol, for homogeneous wireless sensor network. Mathematical analysis reveals that Co-Axial Fixed Cluster (CFC) outperforms LEACH [1] by 683% longer lifetime for the period when WSN remains fully functionally operational. CFC uses fixed cluster and multiple designated cluster-head (CH) nodes at the center of each cluster. Only the designated CHs transmit data to the base station or to another designated CH node. Among the designated cluster-head nodes at the center of each cluster, only one node remains in active state and performs the duty of the CH of the respective cluster. Rest of the designated cluster-head nodes of each cluster remain in sleep state and just prior to the death of current CH node of a cluster, another one from among the designated cluster-head nodes take over the responsibility of the CH. Furthermore, not every active designated CH node of each cluster transmits data to the base station in each round. Rather one of the active designated CH node also acts as second level CH node and receives data from other active designated CH nodes and transmits it to the base station after data fusion. This scheme reduces transmission overhead and increases the lifetime of the WSN significantly.
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The importance and the possibilities of wireless sensor networks (WSNs) are now quite clear, because they can be found in all kinds of applications, from those in our daily life to those in the military. However, the limited energ...
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The importance and the possibilities of wireless sensor networks (WSNs) are now quite clear, because they can be found in all kinds of applications, from those in our daily life to those in the military. However, the limited energy of sensors, i.e., the lifetime problems of WSN, has attracted many researchers from different disciplines. Several recent studies showed that metaheuristic algorithms provide promising solutions to the lifetime problems. This paper begins with a brief review of the lifetime problems and the basic ideas of metaheuristic algorithms. Then, the detailed descriptions of metaheuristic algorithms for solving the lifetime problems from the perspectives of problems and algorithms are given. Some simple examples for illustrating how metaheuristic algorithms can be used to solve the lifetime problems and their performance are given. Several important open and possible research issues are discussed to provide the future research trends of this area.
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A wireless sensor network (WSN) is considered where each node estimates a number of node-specific desired signals by means of the distributed adaptive node-specific signal estimation (DANSE) algorithm. It is assumed that the topol...
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A wireless sensor network (WSN) is considered where each node estimates a number of node-specific desired signals by means of the distributed adaptive node-specific signal estimation (DANSE) algorithm. It is assumed that the topology of the WSN is constructed based on one of the two approaches, either a top-down approach where the WSN is composed of heterogeneous nodes, or a bottom-up approach where the nodes are not necessarily heterogeneous. In the top-down approach, nodes with the largest energy budgets are designated as cluster heads and the remaining nodes form clusters around these nodes. In the bottom-up approach, an ad hoc WSN is partitioned into a set of smaller substructures consisting of non-overlapping cliques that are arranged in a tree topology. These two approaches are shown to be conceptually equivalent, in that the same building blocks constitute both envisaged topologies, and the functionality of the DANSE algorithm is extended to such topologies. In using the DANSE algorithm in such topologies, the WSN converges to the same solution as if all nodes had access to all of the sensor signal observations, and provides faster convergence when compared to DANSE in a single tree topology with only a slight increase in per-node energy usage.
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The handling of multimedia data with Wireless Multimedia Sensor Networks (WMSNs) have very challenging issues compared to the usual scalar Wireless Sensor Network (WSN). Sensors used in multimedia devices are capable of extract vi...
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The handling of multimedia data with Wireless Multimedia Sensor Networks (WMSNs) have very challenging issues compared to the usual scalar Wireless Sensor Network (WSN). Sensors used in multimedia devices are capable of extract video, audio, images, as well as scalar sensor data. The data which are sensed have been collected and distributed through various heterogeneous devices with the help of CMOS cameras and microphones. WMSNs are able to deliver the huge volume of multimedia content with the significant progress by distributed signal processing and multimedia source coding techniques. In this paper, we delineate the comprehensive discussion of multimedia data and their characteristics, research challenges of WMSNs, and errands of communication protocols stack demand wit high bandwidth utilization of multimedia data.
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In Surveillance Wireless Sensor Networks (SWSN), the nodes are distributed at the borders to detect unauthorized intrusions. In such applications, as the nodes are usually equipped with limited batteries and the network area is ha...
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In Surveillance Wireless Sensor Networks (SWSN), the nodes are distributed at the borders to detect unauthorized intrusions. In such applications, as the nodes are usually equipped with limited batteries and the network area is harsh to be accessible for humans, energy efficiency is considered as one of the main issues in designing the sensor networks. In the last years, Wireless Rechargeable Sensor Networks (WRSN) provides valuable insights into solving the energy constraint problem in WSNs. In a WRSN, Wireless Mobile Chargers (WMC) are responsible to recharge the batteries of the sensor nodes in order to enhance the operation time of the network. In most of the previous WRSN based schemes, the WMCs recharge the nodes singly and directly, which results in increasing the travel time of WMC and waiting time of sensor nodes. In addition, despite of using WMC, the permanent network lifetime has not been addressed in most of the previous schemes. Therefore, to overcome the limitations of existing literature, this research work focuses on the design and development of Broker-based Nodes Recharging Scheme (BNRS) which significantly contributes to improved lifetime and performance of SWSN. In the proposed scheme, power banks are employed as brokers between sensor nodes and WMC. The main duty of a power bank is to receive energy from WMC and transfer to the sensor nodes. Based on the simulation experiments the proposed BNRS achieves the permanent network operation which results in increasing security in the border of countries.
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