Coverage Preservation Research Articles

An Efficient Routing Awareness Based Scheduling Approach in Energy Harvesting Wireless Sensor Networks

Wireless sensor networks (WSNs) have emerged as a promising technology for various Internet of Things (IoT)-based sensing applications. Generally, sensor nodes are powered by non-rechargeable and low-capacity batteries; they only last for a small amount of time. Due to their dispersed nature, sensor nodes cannot have their batteries replaced or maintained locally. The energy harvesting (EH) concept shows commitment as a method for addressing the current energy shortage. Another problem is the intra-energy control of various network load functions, including coverage preservation, routing, clustering, etc. This study proposes an ERAS (efficient routing awareness scheduling) algorithm to address the abovementioned issues. The ERAS method employs a solar harvesting system as a hierarchical clustering-based routing protocol. The presented scheme dynamically alters nodes between states and adjusts to new states based on the insides of sensed data packets. Synchronization-based scheduling ensures proper coordination between the cluster head (CH) and cluster members (CMs). It selects the CH based on both remaining and harvested energy and the number of active nodes to improve throughput. Surprisingly proposed EASR algorithm performs efficiently while considering various performance matrices, including network lifetime, packet delivery ratio, energy consumption, and network sustainability. Extensive simulation results exhibit the network lifetime of the proposed ERAS technique (79.8%) compared to ERA, SEED and CREST methods as 67.3%, 73.8%, and 75.2%, respectively.

A Robust Fault-Tolerance Scheme with Coverage Preservation for Planar Topology Based WSN

A Robust Fault-Tolerance Scheme with Coverage Preservation for Planar Topology Based WSN

An algorithm for enhancing coverage and network lifetime in cluster-based Wireless Sensor Networks

Majority of wireless sensor networks (WSNs) clustering protocols in literature have focused on extending network lifetime and little attention has been paid to the coverage preservation as one of the QoS requirements along with network lifetime. In this paper, an algorithm is proposed to be integrated with clustering protocols to improve network lifetime as well as preserve network coverage in heterogeneous wireless sensor networks (HWSNs) where sensor nodes can have different sensing radii and energy attributes. The proposed algorithm works in proactive way to preserve network coverage and extend network lifetime by efficiently leveraging mobility to optimize the average coverage rate using only the nodes that are already deployed in the network. Simulations are conducted to validate the proposed algorithm by showing improvement in network lifetime and enhanced full coverage time with less energy consumption

Restoring mussel beds in highly dynamic environments by lowering environmental stressors

Restoration of coastal ecosystem engineers that trap sediment and dampen waves has proven to be difficult, especially in the wave‐exposed and eroding areas where they are needed the most. Environmental stressors, such as hydrodynamic stress and predation, can only be overcome if transplanted organisms are able to establish self‐facilitating feedbacks. We investigate if the artificial lowering of multiple environmental stressors can be used to give transplanted juveniles the opportunity to form a self‐sustainable system and thereby increase their long‐term survival on wave‐exposed and eroding shores. We designed a large field experiment using juvenile mussels (Mytilus edulis) as model species on a wave‐exposed tidal flat in the Oosterschelde estuary (the Netherlands). We tested if the environmental stress caused by a high predation pressure and wave‐driven dislodgement could be reduced by a combination of artificial structures such as fences (to exclude predatory crabs), attachment substrates (such as coir‐net or oyster shells), and breakwaters. Despite a low overall mussel survival (29%), we found that under strong hydrodynamic conditions, experimental fences and attachment substrates increased the retention of transplanted mussel seed. However, modification of local hydrodynamic conditions using breakwaters did not improve mussel coverage preservation. Overall, this study highlights the potential of using techniques that lower multiple environmental stressors to create a window of opportunity for establishment in highly dynamic ecosystems.

Simultaneous neck coverage and branch preservation using the proximal portion of a self-expandable open-cell stent for embolization of distal internal carotid artery aneurysms: multi-center, long-term results.

We report the long-term results of a modified stent-assisted coil embolization technique using the far proximal part of a self-expanding open-cell stent. The technique was used to cover the neck of the aneurysm while simultaneously preserving the branches of the distal internal carotid artery in patients with aneurysms of the posterior communicating (Pcom) and anterior choroidal arteries (AchA). We performed a retrospective review of the prospectively maintained databases at two tertiary neurosurgical centers to identify all patients who underwent embolization of Pcom or AchA aneurysms using this technique between January 2014 and July 2019. Postoperative and follow-up clinical and radiological results for initial (n = 16) or re-do (n = 4) embolizations were analyzed. We identified 19 patients with 20 (16 Pcom and 4 AchA) unruptured (n = 19) or ruptured (n = 1) aneurysms. Eighteen among 20 stents (90.0%) were deployed successfully, and complete occlusions were initially attained in 18 aneurysms (90.0%). At follow-up examinations 8 to 56months later, 6 of 14 aneurysms (42.8%) showed neck remnants. All of the branches were saved and no thromboembolic event, rupture, or sequelae were noted during or after the procedures. These results suggest that this modified stent-assisted technique is a feasible and reasonable alternative to conventional stent deployment for coil embolization of wide-necked sidewall aneurysms in the distal ICA.

A Greedy Approach for Coverage Hole Detection and Restoration in Wireless Sensor Networks

Wireless sensor network contains several small sensor nodes that are designed to work autonomously. Coverage preservation is an underlying requirement to efficiently deliver certain services in WSN...

Coverage Preservation with Rapid Forwarding in Energy-Harvesting Wireless Sensor Networks for Critical Rare Events

Wireless sensor networks for rarely occurring critical events must maintain sensing coverage and low-latency network connectivity to ensure event detection and subsequent rapid propagation of notification messages. Few algorithms have been proposed that address both coverage and forwarding and those that do are either unconcerned with rapid propagation or are not optimised to handle the constant changes in topology observed in duty-cycled networks. This article proposes an algorithm for Coverage Preservation with Rapid Forwarding (CPRF). The algorithm is shown to deliver perfect coverage maintenance and low-latency guaranteed message propagation whilst allowing stored-charge conservation via collaborative duty cycling in energy-harvesting networks. Favourable comparisons are made against established and recently proposed algorithms in both sparse planned and dense random distributions. Further, an implementation for commercially available wireless sensing devices is evaluated for detection and notification of damage to highway light poles caused by vortex shedding.

Fascia lata as an alternative in dental treatments

Introduction: Fascia lata is the most extreme section of the thigh’s aponeurosis. It is a thick and resistant membrane possessing elasticity, flexibility and memory. It is presently used in the medical world to treat abdominal defects, urinary incontinence, and palpebral ptosis. In dentistry it is used in guided tissue regeneration, root coverage, ridge increase and socket (alveolus) preservation. Method: An electronic search was conducted in the following databases: Medline, PubMed and SciELO, with the term fascia lata. Full texts in English and Spanish were included in timeline spanning from 1983 to 2015. Main characteristic selected for these texts was they explored use of fascia lata and medical and dental areas. Discussion: Limiting situations arose during the execution of this project due to the scarcity found in articles and research papers and documented clinical cases targeting use of fascia lata ion dental areas. Conclusions: Fascia lata is a resorbable, biocompatible material, well tolerated by the recipient bed; when used in medical and dental specialties it exhibits characteristics of accuracy (security) and long duration.

BCoPS: an energy‐efficient routing protocol with coverage preservation

In wireless sensor networks, an energy-efficient routing protocol plays a crucial role in extending the lifetime of the network. In order to realise this, an optimal coverage-preserving scheme (OCoPS) has been proposed by Boukerche et al. in 2005 as an add-on to the Low-energy Adaptive Clustering Hierarchy (LEACH) protocol. This scheme operates alongside another coverage-preserving scheme that excludes redundant nodes if their on-duty neighbours fully overlap in terms of their sensing ranges, hence saving energy. In this study, the authors propose a central angle decision algorithm that ensures that it does not introduce any coverage hole after applying the coverage-preserving scheme. They also propose a base station (BS)-aided clustering routing protocol with a coverage-preserving scheme (BCoPS) to assess the applicability of the authors’ proposed algorithm to routing protocols and verify the performance gains. In BCoPS, energy-intensive tasks for deployed sensor nodes are substituted by the BS to ensure longer network lifetime. The performance of the BCoPS was compared to that of LEACH and OCoPS. The results of simulations carried out in considered scenarios showed that BCoPS outperformed OCoPS by >20% in terms of network lifetime in general, and by >30% when the coverage rate was higher than 80%.

Energy-efficient coverage protocol based on stable and predictive scheduling in wireless sensor networks

One important issue in wireless sensor networks is the area coverage problem. It describes how well a sensing field is supervised by sensors. In fact, an appropriate coverage strategy needs simultaneous activation of a large number of nodes as each location should be covered by at least k sensors, with k > 1 for many applications. Some sensors may be redundant because of overlaps in the nodes’ regions. Therefore, scheduling techniques alternate the redundant sensors’ activity to reduce uniformly their energy consumption. However, frequent alternation between states and repetitive eligibility executions during the scheduling process itself, lead to significant energy waste. In this paper, we propose the Stable and Predictive Energy-aware Coverage Scheduling (SPEC) protocol. It does not only reduce the scheduling energy waste but it extends the coverage lifetime as well. Indeed, SPEC removes useless transitions from the scheduling strategy and prevents the run of unnecessary eligibility executions. Simulation results confirm that SPEC outperforms existing well-known periodic scheduling protocols, in terms of energy preservation, network lifetime and coverage preservation.

Distributed fuzzy logic based energy‐aware and coverage preserving unequal clustering algorithm for wireless sensor networks

SummaryIn an energy‐constrained wireless sensor networks (WSNs), clustering is found to be an effective strategy to minimize the energy depletion of sensor nodes. In clustered WSNs, network is partitioned into set of clusters, each having a coordinator called cluster head (CH), which collects data from its cluster members and forwards it to the base station (BS) via other CHs. Clustered WSNs often suffer from the hot spot problem where CHs closer to the BS die much early because of high energy consumption contributed by the data forwarding load. Such death of nodes results coverage holes in the network very early. In most applications of WSNs, coverage preservation of the target area is a primary measure of quality of service. Considering the energy limitation of sensors, most of the clustering algorithms designed for WSNs focus on energy efficiency while ignoring the coverage requirement. In this paper, we propose a distributed clustering algorithm that uses fuzzy logic to establish a trade‐off between the energy efficiency and coverage requirement. This algorithm considers both energy and coverage parameters during cluster formation to maximize the coverage preservation of target area. Further, to deal with hot spot problem, it forms unequal sized clusters such that more CHs are available closer to BS to share the high data forwarding load. The performance of the proposed clustering algorithm is compared with some of the well‐known existing algorithms under different network scenarios. The simulation results validate the superiority of our algorithm in network lifetime, coverage preservation, and energy efficiency.

Area k-Coverage Optimization Protocol for Heterogeneous Dense Wireless Sensor Networks

Detecting redundant nodes and scheduling their activity is mandatory to prolong the lifetime of a densely-deployed wireless sensor network. Provided that the redundancy check and the scheduling phases both help to preserve the coverage ratio and guarantee energy efficiency. However, most of the solutions usually proposed in the literature, tend to allocate a large number of unnecessary neighbor (re)discovery time slots in the dutycycle of the active nodes. Such a shortcoming is detrimental to battery power conservation. In this paper, we propose a crossing points-based heuristic to fast detect redundant nodes even in heterogeneous networks; then, an integer linear program and a local exclusion based strategy to respectively, formulate and solve the sensing unit scheduling problem. Simulations show that the resulting localized asynchronous protocol outperforms some state-of-the-art solutions with respect to coverage preservation and network lifetime enhancement.

Evidence-Efficient Multihop Clustering Routing Scheme for Large-Scale Wireless Sensor Networks

Energy consumption and transmission reliability are the most common issues in wireless sensor networks (WSNs). By studying the broadcast nature of data transmission in WSNs, the mechanism of guaranteeing reliable transmission is abstracted as propagation of responsibility and availability. The responsibility and availability represent the accumulated evidence of nodes to support reliable transmission. Based on the developed mechanism, an evidence-efficient cluster head rotation strategy and algorithm are presented. Furthermore, backbone construction algorithm is studied to generate the minimum aggregation tree inside the candidate cluster heads. A minimum aggregation tree-based multihop routing scheme is also investigated, which allows the elected cluster heads to choose the optimally main path to forward data locally and dynamically. As a hybridization of the above, an evidence-efficient multihop clustering routing (EEMCR) method is proposed. The EEMCR method is simulated, validated, and compared with some previous algorithms. The experimental results show that EEMCR outperforms them in terms of prolonging network lifetime, improving transmission reliability, postponing emergence of death nodes, enhancing coverage preservation, and degrading energy consumption.

Multi-objective cluster head election in cluster-based wireless sensor networks

Owing to good coverage preservation, cluster-based wireless sensor networks (WSNs) have been widely explored in the context of various potential applications. Yet, selecting the optimal candidates as the cluster heads in clusters that require complete coverage of the monitored area over long periods of time still remains a significant challenge, and needs to be reasonably solved to operate the large-scale WSN systems in an optimal fashion. To address this issue, a multi-objective cluster head election scheme is proposed in this paper, in which, by taking the network coverage and load balance as the optimisation objectives and deducing the objective ranges, cluster head election is conducted as a problem of multi-objectives combination optimisation. And then, by introducing the Metropolis rule of simulated annealing algorithm, an improved particle swarm algorithm is developed to solve this problem, which could restrict the position change of original and new particles in the iteration process and accelerate the convergence speed of the algorithm. The simulation and analytical results are shown to demonstrate the performance on coverage optimisation, and load balance.

Multi-objective cluster head election in cluster-based wireless sensor networks

Owing to good coverage preservation, cluster-based wireless sensor networks (WSNs) have been widely explored in the context of various potential applications. Yet, selecting the optimal candidates as the cluster heads in clusters that require complete coverage of the monitored area over long periods of time still remains a significant challenge, and needs to be reasonably solved to operate the large-scale WSN systems in an optimal fashion. To address this issue, a multi-objective cluster head election scheme is proposed in this paper, in which, by taking the network coverage and load balance as the optimisation objectives and deducing the objective ranges, cluster head election is conducted as a problem of multi-objectives combination optimisation. And then, by introducing the Metropolis rule of simulated annealing algorithm, an improved particle swarm algorithm is developed to solve this problem, which could restrict the position change of original and new particles in the iteration process and accelerate the convergence speed of the algorithm. The simulation and analytical results are shown to demonstrate the performance on coverage optimisation, and load balance.

A Novel Multi-Targets Cycle Control Coverage Preservation Protocol in Wireless Sensor Network

In the process of multi-objective coverage, due to a large number of redundant data which makes for the decrease of effective coverage and high energy consumption, relevant researches are being carried out. For this purpose, a Multi-Targets K-Coverage Preservation Protocol (MTCPP) is proposed. First, the affiliation between sensor nodes and target nodes is constructed through the network model and the solution for coverage expectations of monitoring area is given. Second, in terms of network energy conversion, the network energy is balanced by the schedule of sensor nodes while different qualities of network coverage can be gained through energy conversion among different nodes. Finally, simulation results show that the protocol can decrease the number of active nodes effectively under some coverage requirements, prolonging the network lifetime.

A Novel Nonlinear Multitargetk-Degree Coverage Preservation Protocol in Wireless Sensor Networks

Due to the existence of a large number of redundant data in the process of covering multiple targets, the effective coverage of monitored region decreases, causing the network to consume more energy. To solve this problem, this paper proposes a multitargetk-degree coverage preservation protocol. Firstly, the affiliation between the sensor nodes and target nodes is established in the network model; meanwhile the method used to calculate the coverage expectation value of the monitored region is put forward; secondly, in the aspect of the network energy conversion, use scheduling mechanisms on the sensor nodes to balance the network energy and achieve different network coverage quality with energy conversion between different nodes. Finally, simulation results show that NMCP can improve the network lifetime by effectively reducing the number of active nodes to meet certain coverage requirements.

Coverage hole detection and restoration algorithm for wireless sensor networks

In wireless sensor networks (WSNs), preserving coverage of the target area by the sensor nodes is crucial to deliver certain services. However, a few sensor nodes die during the network operation due to energy constraints which may break the coverage of the target area. We refer this as a coverage hole problem. In this paper, we propose a new algorithm called CHD-CR which attempts to restore the coverage after detecting a coverage hole in the target area. The proposed algorithm mainly consists of coverage hole detection (CHD) and coverage restoration (CR) phases. We design an efficient local mechanism for coverage hole detection and energy efficient technique for its restoration. We test the performance of the proposed algorithm through simulation and the results are compared with the existing algorithms. Simulation results show that the proposed CHD-CR algorithm outperforms the existing algorithms in terms of coverage preservation for longer time.

Memory Efficient Routing Using Bloom Filters in Large Scale Sensor Networks

Performance and lifetime of wireless sensor networks are tightly linked to the used routing protocol. Energy and memory efficiency are some of the main challenges of routing protocols. These challenges are more strict in large scale and dense networks. Numerous amount of routing approaches are published so far, emphasized on energy consumption. However, a few of them addresses the limitations of node memory. This paper introduces a new routing protocol called Bloom filter based routing protocol (BFRP). It reduces memory consumption by replacing a routing table with a Bloom filter. Since the approach is devised for clustered networks, a new clustering algorithm is introduced that takes remaining energy into the account for cluster head election. It also supports networks with churn. Several scenarios are simulated with NS2 and the results are compared to Coverage Preservation Clustering Protocol and Hybrid Energy-efficient Distributed Clustering algorithms. The results approve that BFRP improves energy consumption and show a significant decrease in memory usage.

Implementation of Energy Efficient Coverage Aware Routing Protocol for Wireless Sensor Network Using Genetic Algorithm

In recent years, wireless sensor network have been used in many application such as disaster reservation, agriculture, environmental observation and forecasting .Coverage preservation and energy consumption are two most important issues in wireless sensor networks. To increase the network lifetime, we propose an energy efficient coverage aware routing protocol for wireless sensor network for randomly deployed sensor nodes. Some of the routing protocol is based on energy efficiency and some are based on coverage aware. The proposed routing protocol is based on both the issues i.e. coverage and energy, in which we first find the k-mean i.e. the degree of coverage, so that we can use this in the selection of cluster heads in wireless sensor network by using Genetic Algorithm for increasing network lifetime and coverage. For cluster head selection each node evaluates its k-mean and energy by internal function which used as fitness function in genetic algorithm. The proposed algorithm “Implementation of energy efficient coverage aware routing protocol for Wireless Sensor Network” is designed for homogeneous wireless sensor network. Simulations results show that proposed algorithm increases the network lifetime by reduce the energy consumption and preserve coverage. Simulation is done with MATLAB and a comparison of algorithm with benchmark algorithms is also performed.