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On Energy Hole and Coverage Hole Avoidance in Underwater Wireless Sensor Networks
Abstract
Due to the limited battery capacity of sensor nodes, a minimization of energy consumption is a potential research area in underwater wireless sensor networks (UWSNs). However, energy hole and coverage hole creations lead performance degradation of UWSNs in terms of network lifetime and throughput. In this paper, we address the energy hole creation issue in depth-based routing techniques, and devise a technique to overcome the deficiencies in existing techniques. Besides addressing the energy hole issue, the proposition of a coverage hole repair technique is also part of this paper. In areas of the dense deployment, sensing ranges of nodes redundantly overlap. Our proposed technique takes a benefit of redundant overlapping and repairs a coverage hole during network operation. Simulation results show that our two techniques cohesively conserve nodes' energy, which ultimately maximizes the network lifetime and throughput at the cost of increased delay.
... Various studies have proposed hybrid void-handling strategies in the literature where several void-handling techniques are combined. For example, in [1], [36]- [38], power control and mobility-assisted approaches are combined. In [2], bypassing the void regions as well as power control techniques are jointly utilized. ...
... Hybrid Multi-sink Im-GEDAR & Co-Im-GEDAR [36] Hybrid Multi-sink DA & TPC [37] Hybrid Multi-sink SHORT [38] Hybrid Multi-sink Our Work Bypassing the Void Region Multi-sink joint consideration of bypassing the void regions and mobilityassisted approaches. The existing research on void-handling strategies for UWSNs can also be classified according to the sink architecture type that is utilized in the network into two groups: singlesink and multi-sink. ...
... Void regions occur depending on the location of the single sink floating on the surface of the water. On the other hand, in multi-sink architectures (e.g., [1]- [3], [5], [7], [11], [15]- [18], [22], [23], [28], [30]- [34], [36]- [38]), there are many sink nodes available on the surface of the water, and each sensor node conveys its packets to any of the sink nodes (anycast traffic). In multi-sink architectures, the formation of void regions depends on the point of view of the sink nodes. ...
Underwater wireless sensor networks (UWSNs) typically suffer from the communication void region problem. A common method to handle the void region problem is to re-route the packets around the void regions. As the size of the void regions increases, packets require more hops to circumvent the large void regions, resulting in a short network lifetime. On the other hand, the void region problem is more destructive in UWSNs utilizing a single-sink architecture than a multi-sink architecture since nodes consume excessive energy for bypassing the void regions to reach the sink node, which can be positioned in a hard-to-reach area in single-sink UWSNs. In this work, an integer linear programming (ILP) model is developed for maximizing UWSNs lifetime while bypassing the void regions. Solving the ILP model to optimality, the joint impact of the void region size and the sink architecture type on UWSNs lifetime is investigated. The results show that the performance of UWSNs significantly drops as the size of the void region grows such that UWSNs lifetimes shorten by up to 61% as the total void region size is one-quarter of the network size. Moreover, multi-sink UWSNs yield better performance than single-sink UWSNs in the void region problem.
... Topology control algorithms based on the depth adjustment ability of the nodes are introduced to recover the connectivity in the communication void region [8]. There are also techniques taking a benefit of redundant overlapping and repairing a coverage hole during network operation [9]. ...
... There are also techniques taking a benefit of redundant overlapping. On energy hole and coverage hole avoidance technique in underwater wireless sensor networks is proposed in [9]. It can repair coverage holes as well as energy holes during network operation by moving nodes from redundant coverage areas to the hole areas. ...
Underwater Acoustic Sensor Networks have attracted much attention due to various applications. However, routing voids lead performance degradation of UASNs in terms of network connectivity and packet delivery ratio. In this paper, we propose a Routing Void Prediction and Repairing (RVPR) algorithm in AUV-assisted UASNs, which utilizes AUVs to carry sensor nodes to repair the routing voids when foreseeing the occurrence of voids. First, the repair position is calculated based on Particle Swarm Optimization algorithm by maximizing the connectivity of the void area and minimizing the AUV moving distance. Then, the routing void prediction based on Markov chain model is proposed to ensure that the AUVs come to the repair task before the voids have already formed. Next, we design a task selecting rule to let the AUVs choose the most important and urgent repair task. Lastly, RVPR applies an energy-efficient interaction mechanism among nodes and AUVs, which guarantees reliable operation of the algorithm. In the simulation, the RVPR algorithm is applied in several different types of routing protocols (HHVBF, QELAR, EAVARP). The simulation results show that RVPR algorithm improves the protocol performances in terms of the packet delivery ratio and the link connection. More specifically, when there are 100 nodes deployed in the network, the packet delivery ratio of HHVBF, EAVAPR and QELAR employing RVPR are increased by 29.4%,79% and 65% respectively.
... In this paper, authors have not focused on power optimization of a sensor node, whereas the main aim is to identify the connectivity issues because of holes. There are certain types of holes found in a sensor coverage area; such as sinkholes [15], coverage holes [16], routing holes [3], wormholes [17], jamming holes [18], etc. In general, wireless sensors are much affected by the coverage holes present in the network. ...
... In such scenarios, some of the deployed nodes need to utilize their energy resources in relaying the data of other nodes giving rise to the multi-hop transmission over the network [5]. This increases the rate of utilization of energy resources for sensor nodes that are located near the destination known as the sink.Consequently, these sensor nodes die early giving rise to the Energy Hole problem [6]. Besides, additional bandwidth and energy resources are also consumed in the process of construction and maintenance for the end-to-end data-forwarding path. ...
The Underwater Wireless Sensor Networks (UWSNs) consist of multiple sensor
nodes deployed to monitor some physical factors for numerous aquatic
applications such as ocean environmental monitoring, tactical surveillance and
disaster prevention, etc. Electromagnetic waves do not propagate well due to
their high attenuation and rapid absorption in the aquatic medium. Therefore,
acoustic waves are most feasible in UWSN to achieve better data rates. However,
acoustic waves impose design challenges due to their high bit error rate, limited
bandwidth, and large propagation delays underwater. Moreover, for acoustic
signals, channel interference becomes severe with high power transmission.
Therefore, to avoid any unwanted interference, sensor nodes are restricted to
transmit within shorter ranges. In such scenarios, some of the deployed nodes
need to utilize their energy resources in relaying the data of other nodes. The
relaying sensor nodes deplete their energy at a rigorous rate and die sooner than
other nodes in the network giving rise to the hot region problem, where the sensor nodes near the trajectory suffer severe energy depletion due to consistent
relaying of data of the distant nodes to the AUV. Therefore, this thesis aims to
increase the lifetime of a UWSN by maintaining a uniform energy distribution
among the sensor nodes. This is achieved by employing multiple Autonomous
Underwater Vehicles (AUVs) that traverse the network in elliptical trajectories.
Furthermore, the axis of the trajectory is rotated to mitigate the effect of the hot
region problem. Based on the comprehensive simulations implemented in
MATLAB, it is observed that the proposed scheme improves the performance of
the network lifetime, energy efficiency, and uniform energy distribution among
the sensor nodes.
... However, the existence of energy blind area and coverage blind area leads to the performance degradation of UWSNs in network lifetime and throughput. Latif et al. [24] designed a technology to overcome the shortcomings of the existing technology to solve the problem of energy blind area in depth-based routing technology. In addition to solving the problem of energy blind area, a coverage blind area repair technology Wireless Communications and Mobile Computing is also proposed. ...
Wireless sensor nodes have the characteristics of small size, light weight, simple structure, and limited energy. They are random during deployment in the monitoring area, and the location of nodes is uncertain after deployment. It is easy to have uneven node distribution, resulting in dense nodes in some areas and sparse nodes in some areas. In the area with dense nodes, the monitoring area is covered repeatedly due to the distance between nodes which is too close. In the area with sparse nodes, the problem of covering blind areas appears due to the distance between nodes which is too far. Aiming at the complex structure of underwater wireless sensor networks, a coverage algorithm based on adjusting the nodes spacing is proposed. The algorithm calculates the reasonable distance between adjacent nodes before the wireless sensor node moves. The distance between wireless sensor nodes increases gradually. The simulation results show that the algorithm can make the clustered wireless sensor nodes disperse gradually by reasonably adjusting the distance between wireless sensor nodes, improve the coverage effect of wireless sensor networks, and reduce the energy consumption of wireless sensor nodes.
... Energy hole and coverage avoidance routing (EHCAR) proposed in [20] prevents the energy hole problems along with the coverage hole restoration schemes. In the high density network, coverage of acoustic nodes imbricate regularly. ...
Underwater acoustic sensor networks (UWASN) have enormous applications like investigating oceanographic environment, data gathering, scrutiny, calamity avoidance etc. Cooperative communication becomes mandatory when nodes are distributed far apart especially in the ocean environment. The existing relay selection techniques do not consider the instantaneous channel characteristics while selecting the relay nodes. The relays selected based on the outdated channel state information aggravates or worsens the performance of the rapidly changing or dynamic UWASN. Hence, this paper proposes an instantaneous channel characteristics and progression factor (ICPF) based collaborative routing for underwater acoustic sensor networks. It considers numerous indexes such as propagation delay, residual energy, progression factor, spreading, transmission and absorption loss in the forwarding relay node selection. These indexes are averaged and updated periodically to overcome the difficulties caused by the inconsistency and aggressive nature of underwater channel. The progression factor proposed in this work is a prime metric that facilitates efficient data forwarding. Simulation results show that the proposed technique outperforms the existing schemes in terms of packet delivery ratio (PDR), average end to end delay and energy consumption and is capable of achieving PDR of 90.1% for network comprising of 100 acoustic nodes.
... However, in many applications, precisely when the sensing area is inaccessible or when the deployment is scaling over a large geographical region, sensors are scattered randomly from the air using planes. Due to this random scattering, some areas can be highly covered whereas others are not covered at all resulting in what is known as coverage holes (Latif et al., 2016). Therefore, the random deployment of sensors might not always meet the desired requirements (Ghaddar et al., 2020). ...
... The optimization technology of movement path has made great progress. In terms of node mobility, the EEDBR protocol [8] considers moving the nodes in the non-energy hole area with higher residual energy to the hole area, which can balance the energy consumption of the area and realize the repair of the energy hole. The single sink node movement algorithm is proposed in DGFP protocol [9], the sink node moves along a fixed path throughout the entire network and collects data in each area. ...
The energy hole is one of the problems that wireless sensor networks cannot completely avoid. The existing energy hole suppression strategies lack the analysis of the development trend of energy holes and effective measures. In order to solve these problems, this paper deeply studies the formation process of energy hole, constructs an energy topography model that can reflect the different development states of energy hole. It proposes a series of basic definitions related to energy hole, including node energy surface, energy trough, quasi-energy hole, energy hole, independent energy hole, fusion energy hole, hole edge domain, and the dispersion of dead node. Then, an Energy Hole Suppression Routing Algorithm (EHSRA) for wireless sensor networks is proposed, which includes the cluster head election algorithm for suppressing energy hole, the transmission ordering strategy of the nodes in the cluster, and the data transmission strategy to realize the energy consumption balance of the network and prolong the network lifetime. Simulation experiments show that, compared with EEEHR, EA-BECHA, and DECEM algorithms, the network lifetime of the proposed algorithm is extended by 127.66%, 59.7%, and 48.61% respectively, the total energy consumption of the network is reduced by 48.52%, 21.55%, and 16.9%, respectively. At the same time, the occurrence time of dead node is delayed, and the dispersion of dead node is also higher than other algorithms. It effectively suppresses the occurrence time and expansion speed of energy hole to a certain extent.
... However, in many applications, precisely when the sensing area is inaccessible or when the deployment is scaling over a large geographical region, sensors are scattered randomly from the air using planes. Due to this random scattering, some areas can be highly covered whereas others are not covered at all resulting in what is known as coverage holes (Latif et al., 2016). Therefore, the random deployment of sensors might not always meet the desired requirements (Ghaddar et al., 2020). ...
Nowadays, countless applications benefit from the services provided by wireless sensor networks (WSNs) in remote surveillance and data gathering. Coverage is considered an important quality of service (QoS) criterion for many of these applications. To ensure that the required QoS is achieved, the sensors must be placed in locations that optimise the area coverage and eliminate the coverage holes, especially when deploying sensors with heterogeneous sensing ranges. In this paper, a novel sensor deployment scheme based on the improved bees algorithm (IBA) for optimising the area coverage in both homogeneous and heterogeneous WSNs is proposed. The IBA includes a neighbourhood shrinking procedure that aims to improve the local search efficiency and a site abandonment procedure for preventing the algorithm from the entrapment in a local optimum. Experiments show that the IBA delivers high-quality solutions and optimises the area coverage effectively compared with four state-of-the-art methods in homogeneous and heterogeneous WSNs.
... This hole isolates the sink node from its connected network and henceforth, a short network lifetime [1][2] [3]. Thus, efficient use of energy consumption and how to prolong the lifetime of the network has become the subject of much research [4][5] [6] [7]. A first sensor node that runs out of energy constitutes one important metric of network life [8]. ...
A tree topology is a commonly employed topology for wireless sensor networks (WSN) to connect sensors to one or more remote gateways. In many-to-one traffic, routing imposes a heavy burden on downstream nodes, as the same routes are repeatedly used for packet forwarding from one or more sensor chains. The challenge is traffic paths that ensure balanced energy consumption at sink-hole to protect sensors from fast death. This paper proposes an energy consumption pattern-aware greedy routing protocol that proactively protects many-to-one topology from the sink-hole formation. The proposed protocol, Energy Balance-Based Energy Hole Alleviation in Tree Topology (EBEHA-T), precludes energy hole formation rather than retrospectively responding to a hole detection. Updated status of variations in energy consumption patterns at the sink-hole and construction feature of joint nodes in the tree topology aids in routing decision. Performance evaluation of EBEHA-T against benchmark method RaSMaLai shows increased energy-saving across the entire network and a marked improvement in energy consumption balance in energy hole zones. This precludes energy hole formation and the consequent network partitioning, leading to improved network lifetime beyond that of the RasMaLai.
... This energy hole creation and coverage hole creation methods takes a redundant overlapping and the coverage hole creation repairs throughout the network operation. The coverage hole leads the degradation performance of Underwater Wireless Sensor Networks, in terms of throughput and network lifetime [10]. ...
Underwater Wireless sensor network posses several factors, which causes congestion, issues in the network, like mutual interference, many to one communication, and dynamic changes in the topology of the network. These factors make the network more vulnerable to the occurrence of congestion in the network. Congestion in underwater wireless sensor network leads to the possibility of occurrence of packet loss, over utilisation of node energy and drop in throughput of the network. In order to overcome these issues a cross layer congestion control scheme is introduced over the contention based MAC protocol. The channel information passed by the MAC layer was added with the details about ratio of buffer occupancy and congestion level in the local nodes. The cross layer protocol dynamically adjust the priority of accessing the channel in MAC layer and controls the data transmission rate to control the occurrence of congestion in the network. The performance of the cross layer network is compared with the hierarchical based and cluster based methods by simulating in NS2 simulator and hardware model is developed to analyse the real time constrains in hardware environment.
... Using the sleep scheduling technique, a guaranteed service coverage protocol for wireless sensor networks introduced in Zhang et al. 169 In addition, the sleep scheduling mechanism is controlled by the sleep factor. [170][171][172][173] However, the sleep schedule technique cannot fix the coverage hole in the network precisely, when there is no active and inactive node in the coverage slot area. ...
Service discovery (SD) is the cornerstone of wireless and mobile systems. The discovery of effective service is the key to achieve a higher level of ubiquity, which ensures the availability of services to users and applications significantly, and the high use of services. The research in this field is limited, with a few SD protocols available for specific purposes specified in the 6LoWPAN region. This paper discusses the various issues and challenges facing the design and selection of the appropriate service discovery and cluster-based mechanism. Moreover, attention has been drawn to the cross-layer solution by discussing different clustering techniques used to solve the redundancy problems. Furthermore, the service discovery protocols and cluster-based routing protocols are critically investigated considering the redundancy problem, methods, mechanisms, and architectures by categorizing them into different categories, comparing them with fundamental parameters in the WSNs and MANETs environments. In addition, a modern form is proposed to show the life cycle of the service discovery process, and a new figure has been designed to clarify to the researchers various of the open issues related to the service discovery and cluster-based routing protocols, corresponding objectives and the techniques of solving problems. Through the discussion of the scientific papers under survey, important results and valuable recommendations were reached. The survey is concluded with a summary, open research issues, outlook, and directions for future research on the topic.
... In most underwater routing techniques, data packets are transmitted from bottom to top in a multi-hop transmission mode, where CHs are responsible for the data aggregation and relay. Therefore, the energy of nodes and CHs close to the BS are easily exhausted, thus resulting in energy holes in UASNs [9]. ...
The dynamic topology, narrow transmission bandwidth, and limited energy of sensor nodes in mobile underwater acoustic sensor networks (UASNs) pose challenges to design an efficient and robust network for underwater communications. In this paper, we propose a novel machine learning-based clustering and routing scheme, named energy-efficient clustering and cooperative routing based on improved K-means and Q-learning (ECRKQ), to reduce and balance energy consumption among sensor nodes in a mobile UASN and improve the bandwidth utilization. In the cluster head (CH) selection stage, ECRKQ modifies the K-means algorithm to dynamically select a CH based on the residual energy of the node and the distance from the node to the centroid in a cluster. In the clustering stage, ECRKQ adopts the Q-learning algorithm by incorporating the residual energy of the CH, the energy consumption of data transmission from the node to the CH, and the energy consumption of the data transmission from the CH to the base station into the Q-value function. In the data transmission stage, ECRKQ applies the dynamic coded cooperation (DCC) transmission to improve the bandwidth utilization and the robustness of the underwater communications. In the DCC transmission, cooperative nodes are also dynamically selected based on the residual energy and the energy consumption of transmitting a packet to their destinations. In the simulation, we apply the ocean current drifting model to emulate the position variation of nodes caused by ocean currents in a mobile UASN. The simulation results show that the proposed ECRKQ scheme can achieve more balanced energy consumption among sensor nodes in a mobile UASN than that of the existing scheme.
... Thus, it has better network reliability, and its energy consumption is more balanced. It can avoid the energy hole [24,25] effectively. (2) A novel depth-adjustment self-deployment algorithm based on growth ring style is proposed. ...
The underwater wireless sensor networks (UWSNs) have been applied in lots of fields such as environment monitoring, military surveillance, data collection, etc. Deployment of sensor nodes in 3D UWSNs is a crucial issue, however, it is a challenging problem due to the complex underwater environment. This paper proposes a growth ring style uneven node depth-adjustment self-deployment optimization algorithm (GRSUNDSOA) to improve the coverage and reliability of UWSNs, meanwhile, and to solve the problem of energy holes. In detail, a growth ring style-based scheme is proposed for constructing the connective tree structure of sensor nodes and a global optimal depth-adjustment algorithm with the goal of comprehensive optimization of both maximizing coverage utilization and energy balance is proposed. Initially, the nodes are scattered to the water surface to form a connected network on this 2D plane. Then, starting from sink node, a growth ring style increment strategy is presented to organize the common nodes as tree structures and each root of subtree is determined. Meanwhile, with the goal of global maximizing coverage utilization and energy balance, all nodes depths are computed iteratively. Finally, all the nodes dive to the computed position once and a 3D underwater connected network with non-uniform distribution and balanced energy is constructed. A series of simulation experiments are performed. The simulation results show that the coverage and reliability of UWSN are improved greatly under the condition of full connectivity and energy balance, and the issue of energy hole can be avoided effectively. Therefore, GRSUNDSOA can prolong the lifetime of UWSN significantly.
... In many fields of light and seawater technology, Underwater Wireless Sensor Networks (UWSN) has been monitored in recent years for water pollution monitoring, underwater resource exploration, marine agrometeorological data collection, earthquake, tsunami disaster prevention, and defense security. Applications such as these are receiving increasing attention [2], [3]. The research on underwater sensor networks abroad started relatively early. ...
... As an extension of wireless sensor network in underwater environment, underwater wireless sensor network has the same structure as the basic wireless sensor networks architecture. But underwater sensor network is still a new field facing many challenges due to the special application environment of underwater sensor network [41][42][43][44]. ...
Wireless sensor networks have been widely researched and developed in recent years. The node deployment problem is a multi-dimensional nonlinear optimization problem with continuous discrete variables. In order to improve the coverage effect of wireless sensor networks, a network coverage algorithm based on evidence theory is proposed. The motion direction of the wireless sensor node is calculated. The wireless sensor node is moved to the area with low perception probability. Improve the network coverage effect. Reduce the moving distance of wireless sensor nodes. Extended the service time of wireless sensor network. The simulation results show that this algorithm can improve the coverage effect of the monitoring area and reduce the moving distance of nodes effectively.
... On the other hand, the degree of overlap among sensor nodes is high in a dense deployment. A major research challenge is to develop an inter-operable node scheduling scheme that can operate efficiently independent of the deployment scheme chosen [210]. An increase or decrease in the number of sensor nodes deployed in the network should not affect the node scheduling scheme's efficacy in identifying and activating the cover set. ...
Recent advances in wireless technologies have led to an increased deployment of Wireless Sensor Networks (WSNs) for a plethora of diverse surveillance applications such as health, military, and environmental. However, sensor nodes in WSNs usually suffer from short device lifetime due to severe energy constraints and therefore, cannot guarantee to meet the Quality of Service (QoS) needs of various applications. This is proving to be a major hindrance to the widespread adoption of WSNs for such applications. Therefore, to extend the lifetime of WSNs, it is critical to optimize the energy usage in sensor nodes that are often deployed in remote and hostile terrains. To this effect, several energy management schemes have been proposed recently. Node scheduling is one such strategy that can prolong the lifetime of WSNs and also helps to balance the workload among the sensor nodes. In this paper, we discuss on the energy management techniques of WSN with a particular emphasis on node scheduling and propose an energy management life-cycle model and an energy conservation pyramid to extend the network lifetime of WSNs. We have provided a detailed classification and evaluation of various node scheduling schemes in terms of their ability to fulfill essential QoS requirements, namely coverage, connectivity, fault tolerance, and security.We considered essential design issues such as network type, deployment pattern, sensing model in the classification process. Furthermore, we have discussed the operational characteristics of schemes with their related merits and demerits. We have compared the efficacy of a few well known graph-based scheduling schemes with suitable performance analysis graph. Finally, we study challenges in designing and implementing node scheduling schemes from a QoS perspective and outline open research problems
... Latif et al. address the energy hole creation issue in UWSNs and design a scheme to surmount the shortages in existing methods. The proposed scheme benefits from superfluous overlapping and repairs coverage holes in the process of network operation [17]. In response to the energy constraints in UWSNs, Azam et al. present a Balanced Load Distribution (BLOAD) strategy to shun energy holes generated by imbalanced energy consumption in the UWSNs [18]. ...
It is important for underwater wireless sensor networks (UWSNs) to satisfy the diverse monitoring demands in harsh and perilous three-dimensional underwater environments. After the monitoring missions and demands transform, a large number of underwater event coverage holes will appear. Traditional network repair strategies cannot be applied to the ever-changing underwater monitoring missions and the harsh multi-constrained three-dimensional underwater environments. Multiple autonomous underwater vehicles (multi-AUVs) have strong adaptability and flexibility in perilous and harsh three-dimensional underwater environments. First, an underwater event coverage hole (UECH) repair model under various constraints is proposed. Next, a multi-agent event coverage hole repair algorithm (MECHR), which combines multi-agent strategy with diversity archive strategy, is proposed to repair UECHs in UWSNs. The presented algorithm symmetrically completes subtasks through information exchange and interactive operations with other agents. Unlike existing repair strategies, the MECHR algorithm can effectively repair a large number of UECHs resulted by the transformations in underwater monitoring scenes and demands. The MECHR algorithm can adapt to a wide range of harsh scenes and multi-constrained three-dimensional underwater environments. Eventually, the effect of the MECHR algorithm is verified through underwater repair simulation experiments, which can adapt to the constantly changing three-dimensional underwater monitoring environments.
... In [7], dead nodes, packet loss and energy consumption of dead nodes were simulated on network simulator using Double Cost-based Function Routing and the results were compared with Greedy Geographic Routing. In [8], the problem of energy hole creation in depth-based routing techniques and a technique to overcome the deficiencies in existing techniques were devised. Besides addressing the energy hole issue, the proposition of a coverage hole repair technique is also part of this paper. ...
To solve the energy hole problem in wireless sensor networks with double sinks, a double sink energy hole avoidance strategy is proposed. The main idea is that two data sinks are set at fixed positions on both sides of the rectangular network to collect nodes data in the corresponding area of the network. In the network, sensor nodes are organized in non-uniform clusters. Clusters close to sink have a smaller cluster radius, and clusters far from sink have a larger cluster radius. According to the results of threshold training, monitoring area of double sink is dynamically adjusted based on the difference of energy consumption and load of nodes in the double sink monitoring area, so that the energy consumption load of nodes in the double sink monitoring area tends to be the same, so as to avoid the premature occurrence of energy hole phenomenon in the area with large load, leading to network failure. The experimental results demonstrate that the strategy proposed in this paper can efficiently balance the energy dissipation of double sink and prolong the network energy utilization efficiency and network lifetime.
... In a practical environment, the energy consumption rate varies significantly among sensor nodes [27,28]. For example, sensors that are responsible for more data transmission tend to have higher energy consumption rates than other sensors. ...
Wireless rechargeable sensor networks are widely used in many fields. However, the limited battery capacity of sensor nodes hinders its development. With the help of wireless energy transfer technology, employing a mobile charger to charge sensor nodes wirelessly has become a promising technology for prolonging the lifetime of wireless sensor networks. Considering that the energy consumption rate varies significantly among sensors, we need a better way to model the charging demand of each sensor, such that the sensors are able to be charged multiple times in one charging tour. Therefore, time window is used to represent charging demand. In order to allow the mobile charger to respond to these charging demands in time and transfer more energy to the sensors, we introduce a new metric: charging reward. This new metric enables us to measure the quality of sensor charging. And then, we study the problem of how to schedule the mobile charger to replenish the energy supply of sensors, such that the sum of charging rewards collected by mobile charger on its charging tour is maximized. The sum of the collected charging reward is subject to the energy capacity constraint on the mobile charger and the charging time windows of all sensor nodes. We first prove that this problem is NP-hard. Due to the complexity of the problem, then deep reinforcement learning technique is exploited to obtain the moving path for mobile charger. Finally, experimental simulations are conducted to evaluate the performance of the proposed charging algorithm, and the results show that the proposed scheme is very promising.
... Fast energy depletion at DNs creates energy holes that would consequently cause the isolation of sink nodes and henceforth, short network lifetime [2,3]. Because of the sensor nodes energy constraint, the issue of energy consumption in the network has become the subject of much research on how to prolong the lifetime of the network [4,5]. In recent years, balanced energy consumption over the network has been identified as one of the promising solutions for optimal energy consumption [6][7][8]. ...
A single tree topology is a commonly employed topology for wireless sensor networks (WSN) to connect sensors to one or more remote gateways. However, its many-to-one traffic routing pattern imposes heavy burden on downstream nodes, as the same routes are repeatedly used for packet transfer, from one or more upstream branches. The challenge is how to choose the most optimal routing paths that minimizes energy consumption across the entire network. This paper proposes a proactive energy awareness-based many-to-one traffic routing scheme to alleviate the above said problem referred to as Energy Balance-Based Energy Hole Alleviation in tree topology (EBEHA-T). This protocol combines updated status of variations in energy consumption pattern around sink-hole zones and distribution of joint nodes among the trees. With this approach, EBEHA-T proactively prevents sink-hole formation instead of just a reactive response after they have occurred. Performance evaluation of EBEHA-T against benchmark method RaSMaLai shows increased energy saving across the entire network and a marked improvement in energy consumption balance in energy-hole zones. This precludes energy hole formation and the consequent network partitioning, leading to improved network lifetime beyond that of the RasMaLai. OMNET++ network simulation software has been used for the evaluation.
... The energy balancing of sensor node in UWSN is one of the major issues due to delimited energy resources and replacement of batteries in underwater is very expensive (Latif et al., 2016). The Balanced Load Distribution scheme (Azam et al., 2017), EEEDBR (Khizar et al., 2016) and ODBR (Ahmed et al., 2016) to evade energy holes produced in UWSNs due to irregular utilisation of energy. ...
... The energy balancing of sensor node in UWSN is one of the major issues due to delimited energy resources and replacement of batteries in underwater is very expensive (Latif et al., 2016). The Balanced Load Distribution scheme (Azam et al., 2017), EEEDBR (Khizar et al., 2016) and ODBR (Ahmed et al., 2016) to evade energy holes produced in UWSNs due to irregular utilisation of energy. ...
... K. Latif, et.al. [13], propose a routing scheme Density controlled Divide and Rule (DDR), in which authors further improve the shortcoming of DR scheme by adding density control technique. In this scheme, the energy-hole issue is reduced significantly. ...
... In [37], inspired by HORA [30], the authors proposed a spherical hole repair technique (SHORT) to repair the coverage and energy holes problem in underwater wireless sensor networks (UWSNs). Similarly to HORA, in SHORT, higher overlapping nodes are responsible for hole reparation. ...
UnderWaterAcoustic Sensor Networks (UW-ASNs) are the newest technological achievement in terms of communication. Composed of a set of communicating underwater sensors, UW-ASNs are intended to observe and explore lakes, rivers, seas and oceans. Recently, they have been subject to a special attention due to their great potential in terms of promising applications in various domains (military, environmental, scientific...) and to the new scientific issues they raise. A great challenging issue in UW-ASNs is the fast energy depletion since high power is needed for acoustic communication while sensors battery budget is limited. Hence, energy-efficient networking protocols are of a paramount importance to make judicious use of the available energy budget while considering the distinguishing underwater environment characteristics. In this context, this thesis aims at studying the main challenging underwater acoustic sensors characteristics to design energy-efficient communication protocols specifically at the routing and MAC layers. First, we address the problem of energy holes in UW-ASNs. The sink-hole problem occurs when the closest nodes to sink drain their energy faster due to their heavier load. Indeed, those sensors especially the ones that are 1-hop away from the static sink act as relays to it on behalf of all other sensors, thus suffering from severe energy depletion. In particular, at the routing layer, we propose to distribute the transmission load at each sensor among several potential neighbors, assuming that sensors can adjust their communication range among two levels when they send or forward data. Specifically, we determine for each sensor the set of next hops with the associated load weights that lead to a fair energy depletion among all sensors in the network. Then, we extend our balanced routing strategy by assuming that each sensor node is not only able to adjust its transmission power to 2 levels but eventually up to n levels where n > 2. Consequently, at the routing layer, for each possible value of n, we determine for each sensor the set of possible next hops with the associated load weights that lead to a fair energy consumption among all sensors in the network. Moreover, we derive the optimal number of transmission powers n that balances the energy consumption among all sensors for each network configuration. In addition to that, it is worth pointing out that our extended routing protocol uses a more realistic time varying channel model that takes into account most of the fundamental characteristics of the underwater acoustic propagation. Analytical results show that further energy saving is achieved by our extended routing scheme. Second, to mitigate the dramatic collision impacts, we design a collision avoidance energy efficient multichannel MAC protocol (MC-UWMAC) for UW-ASNs. MC-UWMAC operates on single slotted control and a set of equal-bandwidth data channels. Control channel slots are dedicated to RTS/CTS handshaking allowing a communicating node pair to agree on the start time of communication on a pre-allocated data channel. In this thesis, we propose two novel coupled slot assignment and data channels allocation procedures without requiring any extra negotiation overhead. Accordingly, each node can initiate RTS/CTS exchange only at its assigned slot calculated using a slot allocation procedure based on a grid virtual partition of the deployment area. Moreover, for each communicating pair of nodes, one data channel is allocated using a channel allocation procedure based on our newly designed concept of singleton- intersecting quorum. Accordingly, each pair of communicating nodes will have at their disposal a unique 2-hop conflict free data channel. Compared with existing MAC protocol, MC-UWMAC reduces experienced collisions and improves network throughput while minimizing energy consumption.
... The total traffic is used to determine load balancing for both direct transmission and hop by hop transmission [10]. To avoid the overhead, the nodes had to update frequently with its residual energy [12] [11]. If the energy of the node reaches zero, it dies [14]. ...
Underwater Wireless Sensor Networks (UWSN) is one of the emerging technologies. Nowadays, it is more useful to monitor the watery bodies and underwater environment. Energy is one of the main issues in Underwater Wireless Sensor Nodes. Depends on the energy of each node in the network, the transmission rate varies. The nodes in the underwater networks had limited energy so it had to monitor the nodes effectively. In this work, the E-GEDAR protocol is used to analyze the data transmission rates and energy consumption as well as the efficiently. Simulation results show the significant improvement in the above parameters when compared with GEDAR protocol.
... To cope with the hot-spot problem, mobile sinks are used in many routing protocols [7] for data collection from sensor nodes in their vicinity. Furthermore, in existing protocols [8] sensor nodes near sink are often nominated for data sending, such unstable load of transmission on these nodes cause initial death of sensor nodes and produce energy holes in the network [9]. As a result of these energy holes, some areas in the network remain un-sensed. ...
Underwater Wireless Sensor Networks (UWSNs) have emerged as a remarkable interest for
scholars worldwide in terms of various applications such as monitoring offshore oil and gas reservoirs,
pollution, oceans for defense, and other applications such as tsunami. Terrestrial Wireless Sensor Networks (TWSN) and UWSNs share many characteristics apart from having different communication medium
and working environment as UWSNs face the challenges of low-bandwidth, long latency, and high bit error
rate. These have caused for UWSNs many problems such as low reliability, packet retransmission, and
high consumption of energy. To alleviate the aforementioned issues, many techniques have been proposed.
However, most of them merely consider the issue of hotspot which occurs due to the unbalanced transmission
of load on sensor nodes near the surface sink. In this article, we propose a multi-layer cluster-based Energy
Ef cient (MLCEE) protocol for UWSNs to address the issue of hotspot and energy consumption. There
are different stages in MLCEE, rst of which is the division of the whole network in layers, the second is
clustering of the nodes at same layers. In the last stage of transmission, the cluster head (CH) selects the
next hop among the CHs based on greater tness value, small Hopid and small layer number. To mitigate
the issue of hotspot, the rst layer remains un-clustered and any node in the rst layer transfers data to the
sink directly while cluster heads (CHs) are selected based on Bayesian Probability and residual energy. The
simulation results of the proposed technique, done using MATLAB, have revealed that MLCEE achieves
superior performance than the other techniques with regard to the network lifetime, energy consumption,
and data transmission amount.
... The forwarding node waits for a specified period, which is proportional to its depth to avoid the involvement of multiple nodes to forward the same packet. Later, many depth-based power-efficient protocols [3,5,48,49] have been proposed to address the challenges of the underwater sensor network (UWSN). However, extra battery power is required to estimate the depth of a node in such routing methods. ...
The Internet of Things (IoT) has facilitated services without human intervention for a wide range of applications, including underwater monitoring, where sensors are located at various depths, and data must be transmitted to surface base stations for storage and processing. Ensuring that data transmitted across hierarchical sensor networks are kept secure and private without high computational cost remains a challenge. In this paper, we propose a multilevel sensor monitoring architecture. Our proposal includes a layer-based architecture consisting of Fog and Cloud elements to process and store and process the Internet of Underwater Things (IoUT) data securely with customized Blockchain technology. The secure routing of IoUT data through the hierarchical topology ensures the legitimacy of data sources. A security and performance analysis was performed to show that the architecture can collect data from IoUT devices in the monitoring region efficiently and securely.
... To cope with the hot-spot problem, mobile sinks are used in many routing protocols [7] for data collection from sensor nodes in their vicinity. Furthermore, in existing protocols [8] sensor nodes near sink are often nominated for data sending, such unstable load of transmission on these nodes cause initial death of sensor nodes and produce energy holes in the network [9]. As a result of these energy holes, some areas in the network remain un-sensed. ...
Underwater Wireless Sensor Networks (UWSNs) have emerged as a remarkable interest for scholars worldwide in terms of various applications such as monitoring offshore oil and gas reservoirs, pollution, oceans for defense, and other applications such as tsunami. Terrestrial Wireless Sensor Networks (TWSN) and UWSNs share many characteristics apart from having different communication medium and working environment as UWSNs face the challenges of low-bandwidth, long latency, and high bit error rate. These have caused for UWSNs many problems such as low reliability, packet retransmission, and high consumption of energy. To alleviate the aforementioned issues, many techniques have been proposed. However, most of them merely consider the issue of hotspot which occurs due to the unbalanced transmission of load on sensor nodes near the surface sink. In this article, we propose a multi-layer cluster-based Energy Efficient (MLCEE) protocol for UWSNs to address the issue of hotspot and energy consumption. There are different stages in MLCEE, first of which is the division of the whole network in layers, the second is clustering of the nodes at same layers. In the last stage of transmission, the cluster head (CH) selects the next hop among the CHs based on greater fitness value, small Hopid and small layer number. To mitigate the issue of hotspot, the first layer remains un-clustered and any node in the first layer transfers data to the sink directly while cluster heads (CHs) are selected based on Bayesian Probability and residual energy. The simulation results of the proposed technique, done using MATLAB, have revealed that MLCEE achieves superior performance than the other techniques with regard to the network lifetime, energy consumption, and data transmission amount.
... However, such a network structure is not without problems. Since the nodes close to the Sink need to forward data from other nodes in the same cluster, they exhaust their energy quickly, leading to an energy-hole around the Sink [6]. In this case, the network will be gradually divided into more and more areas that can not communicate with each other, resulting in rapid failure of the entire system. ...
In the era of Big Data and Mobile Internet, how to ensure the terminal devices (e.g., sensor nodes) work steadily for a long time is one of the key issues to improve the efficiency of the whole network. However, a lot of facts have shown that the unattended equipments are prone to failure due to energy exhaustion, physical damage and other reasons. This may result in the emergence of energy-hole, seriously affecting network performance and shortening its lifetime. To reduce data redundancy and avoid the generation of sensing blind areas, a type of Virtual Force based Energy-hole Mitigation strategy (VFEM) is proposed in this paper. Firstly, the virtual force (gravitation and repulsion) between nodes is introduced that makes nodes distribute as uniformly as possible. Secondly, in order to alleviate the "energy-hole problem", the network is divided into several annuluses with the same width. Then, another type of virtual force, named "virtual gravity generated by annulus", is proposed to further optimize the positions of nodes in each annulus. Finally, with the help of the "data forwarding area", the optimal paths for data uploading can be selected out, which effectively balances energy consumption of nodes. Experiment results show that, VFEM has a relatively good performance on postponing the generation time of energy-holes as well as prolonging the network lifetime compared with other typical energy-hole mitigation methods.
... The energy balancing of sensor node in UWSN is one of the major issues due to delimited energy resources and replacement of batteries in underwater is very expensive (Latif et al., 2016). The Balanced Load Distribution scheme (Azam et al., 2017), EEEDBR (Khizar et al., 2016) and ODBR (Ahmed et al., 2016) to evade energy holes produced in UWSNs due to irregular utilisation of energy. ...
The advance management of the power supply to load such as in homes, offices etc. and power from source to central network in smart grid system with lowest possible loss is considered here in this paper using the concept of energy internet. It also includes the complete details of power flow and control. In this paper, the efficiency of transmission is increased by using energy routers based on open shortest path first (OSPF) protocol, a new concept in the field of energy internet. By using energy local area network (e -LAN) concept, all the energy routers are connected by using OSPF protocols and virtual circuit concept theory. An algorithm is proposed for efficient power transmission and effective selection of sources to minimize the overall cost in the network.
Wireless sensor network (WSN) is one of the latest developments in communication networks. The major component of a wireless sensor network is the sensor nodes, which monitor a particular area and environment in the deployed region. Therefore, WSN is responsible for controlling and managing the system and environmental conditions in the region of interest (RoI). Sensor nodes can be deployed manually or randomly where random deployment is easy but creates many challenges like mobility, coverage and connectivity, transmission capability, etc. So, in this research, we have focused on handling the problem of coverage and connectivity issues by healing the holes created due to external factors. In the first step, we check the sensor positions and holes in the network. In the second step, we calculate the centroid of holes and its neighbor nodes, and in the last step, we choose a target node to move to the centroid for hole healing. For this, we consider only the holes within the network. The holes are not addressed which are the result of the initial deployment and exist on the border.KeywordsWSNLocalizationCoverage and connectivityNode mobilityHole healing
Random geometric graphs can be used in constructing topology formations for wireless ad-hoc networks (WANETs), including wireless sensor networks, flying ad-hoc networks, and others. They are useful for energy-saving schemes where a randomly alternating subset of deployed nodes is turned off temporarily (without compromising the network connectivity). This also improves network security by periodically re-routing the data flow, which makes it harder for third parties to run a traffic analysis. In the area and target coverage scenarios, a WANET deployment is desired to have maximal area coverage efficiency, which implies covering the largest possible area using the fewest number of nodes by maintaining the connectivity as well. Although deterministic topology formations offering optimal area coverage are known, a random node deployment method that grants connectivity and area coverage maximality has not been presented, to the best of our knowledge. This study introduces a novel topology formation method, called CoRMAC, that consistently yields tree-formed random geometric graphs that are guaranteed to be connected and offer maximal area coverage for any given area size and node cardinality. The area coverage maximality of CoRMAC is formally proven. Extensive theoretical and computational analyses have been provided to demonstrate its graph-theoretic, Euclidean, and networking features. Moreover, comparisons were made with other approaches to show the effectiveness of the proposed method.
Gathering the useful information or data from the sensor nodes is the main purpose of WSN. Consumption of energy varies from one node to another node since the data present in the network goes through one or many sensor nodes. As a result of this, the node containing excess load might lose its battery power supply and will cease to function. If the same scenario occurs to a group of neighboring nodes, then all the nodes fall into a stage of premature death which results in the formation of energy-hole within the network. Due to this, the network’s lifetime gets affected and might get over very soon. The above said issue is identified as the key problem in the work. The projected method aims maximization of coverage by enhancing the detection range of remaining nodes to minimize energy holes using the lively bonding and the division of coverage. The projected method increases the lifetime as compared to the existing protocols.
Wireless energy transfer (WET) is a revolutionary method that has the power to tackle the energy and longevity challenges in wireless sensor networks (WSN). This paper uses a mobile charger (MC) to discover the procedure of WET based on a wireless sensor network (WSN) for a periodic charging technique to maintain the network operational. The goal of this work is to lower overall system energy consumption and total distance traveled while increasing the mobile charger device vacation time ratio. Based on an analysis of total energy consumption, a new metaheuristic called mayfly algorithm (MA) is used to achieve energy savings. Instead of charging all nodes at the same time in each cycle, in our strategy, the mobile charger charges only energy-hungry nodes due to their levels of energy. In this strategy, when the first node reaches the calculated minimum energy, it notifies the base station (BS), which computes all nodes that fall under threshold energy and sends the MC to charge all of them to the maximum energy level in the same cycle. Mathematical results show that the mayfly algorithm can considerably decrease the charging device’s total energy consumption and distance traveled while maintaining performance because it can keep the network operational with less complexity than other schemes.
Wireless sensor networks, one of the basic technologies of remote environmental monitoring, can provide efficient sensing and communication services under limited energy supply. Coverage control is an important method to ensure efficient communication and reliable data transmission. Given the complex physical environments, which impede the energy supplement and recovery of sensor nodes, the motivation of our research is to repair the coverage holes and reduce the energy consumption during the deployment of sensor nodes. Firstly, the variable spiral position update and the adaptive inertia weight strategy are adopted to improve local development and global search ability of the moth flame algorithm. Secondly, we analyze the virtual force of nodes, including the attractive force of uncovered grid points, the virtual force between adjacent sensor nodes and the repulsive force of boundary. The node resultant force is used as the disturbance factor of moth position updating to optimize the path, which effectively avoids the “premature” problem of the algorithm and accelerates global convergence. Finally, moth search is used to guide nodes to move to the area with coverage holes to achieve coverage optimization. In addition, we limit the random walking range of moths to reduce the moving distance. The simulation results show that compared with VFPSO, VFA and MFO algorithms, the coverage rate of VF-IMFO algorithm is increased by 7.16%, 3.85% and 22.2%, and the average moving distance of nodes is reduced by 9.01
$\textbf {m}$
, 0.51
$\textbf {m}$
and 32.46
$\textbf {m}$
respectively. Moreover, under different deployment environments, the VF-IMFO algorithm still maintains remarkable performance advantages.
Given the unique characteristics of UWSNs, the provision of mountable and energy effective routing in underwater sensor networks (UWSNs) is very hard to achieve. Because of the fact that the nodes are randomly deployed and energy harvesting cannot be employed, the problem of void hole arises which is regarded as the most challenging problem in design of routing protocols. These are the areas where the packet cannot be further forwarded using greedy mode. The void or energy hole creation leads to performance degradation in these networks in terms of energy consumption, throughput, and network lifetime. The paper works on the concept of detecting the void nodes prior and follow proactive routing in which paths can be updated at regular intervals. Holding times can be reduced by using two-hop information. The paper deals with these aspects of the routing process. In terms of energy economy, packet delivery ratio, and end-to-end delay, simulation results show that the proposed protocol outperforms Depth based Routing and WDFAD-DBR routing.
We consider an underwater optical wireless communication network in which an autonomous underwater vehicle (AUV) fleet is used to collect information from seabed sensors. Specifically, AUVs cover circular areas or cells and sensors are required to form associations with AUVs for uplink communication. To this end, we propose an efficient algorithm using four-adjacency or eight-adjacency maneuvers to find the optimum AUV positions such that the number of sensors assigned to a cell is maximized. The proposed algorithm, despite its low implementation complexity, achieves near identical coverage as compared to the brute force optimal solution for different parameters such as sensor density, AUV number and height. We also extended our algorithm to consider sensor coverage when they have high/low priority levels.
Underwater wireless sensor network is characterized with dynamic network topology owing to node mobility. Frequent changes in position of nodes due to water current cause network partitioning. This often results in frequent network failures and causes void spaces. Frequent network failures lead to unreliable data transmissions where nodes injudiciously drain their power resource. Such a network needs to adapt its network routing in order to diminish the challenges caused by node mobility. A dynamic approach addressing the issues of node mobility will also enhance the network lifetime. Node mobility creates articulation points (AP) in the network topology. AP is similar to bridges in a graph. AP leads to partitioning of the network that only yields failed and unreliable transmission. Cat Swarm Optimization is explored here for detecting a possible partition in the network prior to its occurrence in the seeking mode of the algorithm. In the tracking mode of the algorithm the cat with the closest distance to the predicted AP is selected to move towards the predicted AP in order to avoid the network from partitioning. The proposed approach enhances the network lifetime as it avoids disconnections and failed transmissions. It would conserve energy consumption of nodes by reducing the possibilities of failed and retried transmissions.
A wireless sensor network (WSN) contains sensor nodes that can forecast the ambience and operate accordingly to transmit the information in adverse surroundings. Though, inadequate energy as well as protection effects limits better transactions in the network. Conventional energy-based schemes utilizing cluster heads (CHs) as well as security is rendered using encryption. Yet, cluster method using encryption security is difficult due to increases the routing complexity as well as routing overhead. So, it degrades the performance of the network. To resolve these problems, Rabin-Karp Algorithm based Malevolent Node Detection and Energy-Efficient Data Gathering approach (RAMD) in WSN is proposed. In this scheme, the Rabin-Karp Algorithm thereby isolates the malevolent sensor from the network. It also removes the eavesdropping attack, and verifies the sensor authentication in the WSN. The sensor nodes forward the supervise data to CH. This CH is elected by cooperativeness rank, data transmission rank and remaining energy. The Mobile sink (MS) is used to gather the sensing data from the CH via intermediate CHs. Thus it reduces both the delay and the additional energy utilization in the network. This approach is mainly used for military or other security application. The simulation outcomes demonstrate that the RAMD is increasing the remaining energy and packet forwarding rate as well as diminishes the delay in the network.
Living in a gastric ulcer of the gastric mucosa of Helicobacter pylori is such a peptic ulcer that can cause serious illnesses such as common bacteria such as gastric cancer and gastrointestinal lymphoma. After being implanted in the gastric, endoscopes are used by nurses and auxiliary gastroscopies to check the risk of infection. At the health center, smart wireless devices can reduce the burden on the medical staff. These devices include low-power wireless sensors and receivers. Prince of Wales Medical can operate repeaters of the Prince of Medical Network. Use multiple sensor data sent through the main central controller to assist the wireless sensor device. They can use more than one to improve the performance of your medical wireless network. The current solution to prevent floor pain is to use various techniques to move and move the patient. Possible for some patients and dangerous for others, which can cause problems for healthcare providers. Meanwhile, the development of information technology in medical systems, including Medical Sensor Network (MSN) applications, has provided convenient service delivery. Smart bed and mattress, alone or used in combination with other technologies. It can provide all of the new features. A more comfortable and safe thing is usually a function related to a conventional medical mattress.
Recently, underwater wireless sensor networks were proposed to explore underwater environment for scientific, commercial and military purposes. However, the limited energy of nodes is a challenge for underwater wireless sensor networks. To prolong the lifetime of battery-limited underwater wireless sensor networks, in this paper, a fault-tolerant topology that can effectively extend the network lifetime is proposed. Initially, the influence of node residual energy and load on node lifetime is analysed. Later the lifetime model of underwater wireless sensor networks is established, and the value range of node load adjustment coefficient satisfying network lifetime is obtained. Finally, the scale-free fault-tolerant evolution model with network lifetime optimization is built based on node residual energy and load case. In addition, simulation experiments are performed to validate performances of the new topology generated by the evolution model built. The results show that the new topology structure can balance the energy consumption of the nodes and prolong the network lifetime effectively, and has good fault tolerance.
The underwater acoustic channel is characterized by a path loss that depends not only on the transmission distance, but also on the signal frequency. As a consequence, transmission bandwidth depends on the transmission distance, a feature that distinguishes an underwater acoustic system from a terrestrial radio system. The exact relationship between power, transmission band, distance and capacity for the Gaussian noise scenario is a complicated one. This work provides a closed-form approximate model for 1) power consumption, 2) band-edge frequency and 3) bandwidth as functions of distance and capacity required for a data link. This approximate model is obtained by numerical evaluation of analytical results which takes into account physical models of acoustic propagation loss and ambient noise. The closed-form approximations may become useful tools in the design and analysis of underwater acoustic networks.
In wireless sensor networks, random deployment of nodes may cause serious coverage overlapping among the nodes and the original network may suffer severe coverage problems due to death of the nodes after deployment. In this paper, efficient distributed coverage hole repair algorithms are proposed taking density of the nodes in the post deployment scenario. The proposed algorithms consider limited mobility of the nodes and can select the mobile nodes based on their degree of coverage overlapping. In order to repair coverage holes of the network, nodes with higher degree of density are moved to maintain uniform network density without increasing the coverage degree of the neighbors of a mobile node. Simulation results show that the energy consumption due to mobility of nodes is least as compared to other similar protocols of the Wireless Sensor Networks. Besides, it is observed that substantial amount of coverage overlapping can be minimized and percentage of coverage of the holes can be maximized.
In this paper, we discuss a 3-dimensional localization sensor node using EM waves (Electromagnetic waves) with RSSI (Received Signal Strength Indicator). Generally EM waves cannot be used in underwater environment, because the signal is highly attenuated by the water medium according to the distance. Although the signal quickly reduces in underwater, the reducing tendency is very clear and uniform. Hence EM waves have possibility as underwater distance sensors. The authors have verified the possibility by theory and several experiments, and developed calibration methods in case of linear and planer environment. For 3-dimensional localization in underwater, it must be known antenna's radiation pattern property in electric plane(called E-plane). In this paper, we proceed experiments to verify attenuation tendency with z axis movement, PLF (Polarization Loss Factor) and ILF (Inclination Loss Factor) with its theoretical approach.
Recently, underwater wireless sensor networks (UWSNs) have attracted much research attention from both academia and industry, in order to explore the vast underwater environment. UWSNs have peculiar characteristics; that is, they have large propagation delay, high error rate, low bandwidth, and limited energy. Therefore, designing network/routing protocols for UWSNs is very challenging. Also, in UWSNs, improving the energy efficiency is one of the most important issues since the replacement of the batteries of underwater sensor nodes is very expensive due to the unpleasant underwater environment. In this paper, we therefore propose an energy efficient routing protocol, named (energy-efficient depth-based routing protocol) EEDBR for UWSNs. EEDBR utilizes the depth of sensor nodes for forwarding data packets. Furthermore, the residual energy of sensor nodes is also taken into account in order to improve the network lifetime. Based on the comprehensive simulation using NS2, we observe that EEDBR contributes to the performance improvements in terms of the network lifetime, energy consumption, and end-to-end delay. A previous version of this paper was accepted in AST-2011 conference.
In this paper, we tackle one fundamental problem in Underwater Sensor Networks (UWSNs): robust, scalable and energy efficient
routing. UWSNs are significantly different from terrestrial sensor networks in the following aspects: low bandwidth, high
latency, node float mobility (resulting in high network dynamics), high error probability, and 3-dimensional space. These
new features bring many challenges to the network protocol design of UWSNs. In this paper, we propose a novel routing protocol,
called vector-based forwarding (VBF), to provide robust, scalable and energy efficient routing. VBF is essentially a position-based
routing approach: nodes close to the “vector” from the source to the destination will forward the message. In this way, only
a small fraction of the nodes are involved in routing. VBF also adopts a localized and distributed self-adaptation algorithm
which allows nodes to weigh the benefit of forwarding packets and thus reduce energy consumption by discarding the low benefit
packets. Through simulation experiments, we show the promising performance of VBF.
Underwater acoustic sensor networks (UWA-SNs) are envisioned to perform monitoring tasks over the large portion of the world covered by oceans. Due to economics and the large area of the ocean, UWA-SNs are mainly sparsely deployed networks nowadays. The limited battery resources is a big challenge for the deployment of such long-term sensor networks. Unbalanced battery energy consumption will lead to early energy depletion of nodes, which partitions the whole networks and impairs the integrity of the monitoring datasets or even results in the collapse of the entire networks. On the contrary, balanced energy dissipation of nodes can prolong the lifetime of such networks. In this paper, we focus on the energy balance dissipation problem of two types of sparsely deployed UWA-SNs: underwater moored monitoring systems and sparsely deployed two-dimensional UWA-SNs. We first analyze the reasons of unbalanced energy consumption in such networks, then we propose two energy balanced strategies to maximize the lifetime of networks both in shallow and deep water. Finally, we evaluate our methods by simulations and the results show that the two strategies can achieve balanced energy consumption per node while at the same time prolong the networks lifetime.
Underwater sensor nodes will find applications in oceanographic data collection, pollution monitoring, offshore exploration, disaster prevention, assisted navigation and tactical surveillance applications. Moreover, unmanned or autonomous underwater vehicles (UUVs, AUVs), equipped with sensors, will enable the exploration of natural undersea resources and gathering of scientific data in collaborative monitoring missions. Underwater acoustic networking is the enabling technology for these applications. Underwater networks consist of a variable number of sensors and vehicles that are deployed to perform collaborative monitoring tasks over a given area.In this paper, several fundamental key aspects of underwater acoustic communications are investigated. Different architectures for two-dimensional and three-dimensional underwater sensor networks are discussed, and the characteristics of the underwater channel are detailed. The main challenges for the development of efficient networking solutions posed by the underwater environment are detailed and a cross-layer approach to the integration of all communication functionalities is suggested. Furthermore, open research issues are discussed and possible solution approaches are outlined.
In this paper, a new wireless sensor network architecture is introduced for underwater surveillance systems where sensors lie in surface buoys when nodes are first deployed. After deployment, sensors are lowered to various depths selected by our scheme such that the maximum coverage of the three dimensional sensor space is maintained. Each node has multiple microsensors of various types; acoustic, magnetic, radiation and mechanical. A classification based data mining scheme based on the readings of these sensor types detects and classifies submarines, small delivery vehicles, mines and divers.
Recently, Wireless Sensor Networks (WSNs) have attracted lot of attention due to their pervasive nature and their wide deployment in Internet of Things, Cyber Physical Systems, and other emerging areas. The limited energy associated with WSNs is a major bottleneck of WSN technologies. To overcome this major limitation, the design and development of efficient and high performance energy harvesting systems for WSN environments are being explored. We present a comprehensive taxonomy of the various energy harvesting sources that can be used by WSNs. We also discuss various recently proposed energy prediction models that have the potential to maximize the energy harvested in WSNs. Finally, we identify some of the challenges that still need to be addressed to develop cost-effective, efficient, and reliable energy harvesting systems for the WSN environment.
Water plays a vital role in the proper functioning
of the Earth’s ecosystems, and practically
all human activities, such as agriculture, manufacturing,
transportation, and energy production.
The proliferation of industrial and agricultural
activities in modern society, however, poses
threats to water resources in the form of chemical,
biological, and thermal pollution. On the
other hand, tremendous advancements in science
and technology offer valuable tools to
address water sustainability challenges. Key technologies,
including sensing technology, wireless
communications and networking, hydrodynamic
modeling, data analysis, and control, enable
intelligently wireless networked water cyberphysical
systems (CPS) with embedded sensors,
processors, and actuators that can sense and
interact with the water environment. This article
provides an overview of water CPS for sustainability
from four critical aspects: sensing and
instrumentation; communications and networking;
computing; and control. The article also
explores opportunities and design challenges of
relevant techniques.
Water plays a vital role in the proper functioning of the Earth’s ecosystems, and practically
all human activities, such as agriculture, manufacturing, transportation, and energy production.
The proliferation of industrial and agricultural activities in modern society, however, poses
threats to water resources in the form of chemical, biological, and thermal pollution. On the other hand, tremendous advancements in science and technology offer valuable tools to address water sustainability challenges. Key technologies, including sensing technology, wireless communications and networking, hydrodynamic modeling, data analysis, and control, enable intelligently wireless networked water cyberphysical systems (CPS) with embedded sensors, processors, and actuators that can sense and
interact with the water environment. This article provides an overview of water CPS for sustainability
from four critical aspects: sensing and instrumentation; communications and networking;
computing; and control. The article also explores opportunities and design challenges of
relevant techniques.
IEEE 802.15.4 standard is a relatively new standard designed for low power low data rate wireless sensor networks (WSN), which has a wide range of applications, e.g., environment monitoring, e-health, home and industry automation. In this paper, we investigate the problems of hidden devices in coverage overlapped IEEE 802.15.4 WSNs, which is likely to arise when multiple 802.15.4 WSNs are deployed closely and independently. We consider a typical scenario of two 802.15.4 WSNs with partial coverage overlapping and propose a Markov-chain based analytical model to reveal the performance degradation due to the hidden devices from the coverage overlapping. Impacts of the hidden devices and network sleeping modes on saturated throughput and energy consumption are modeled. The analytic model is verified by simulations, which can provide the insights to network design and planning when multiple 802.15.4 WSNs are deployed closely.
Energy conservation is one of the challenging tasks in Wireless Sensor Networks (WSNs) whether deployed on ground or underwater. Applications of Underwater Sensor Networks (UWSNs) are gradually increasing due to the remote nature of control and automatic data transmission to onshore base stations. However, this automatic mechanism of WSNs is totally based on their built-in battery, which can not be replaced during network operation. Depth based routing is a popular routing technique which, do not needs full dimensional location information. However, consideration of depth and residual energy information for selection of next hop are not enough for balanced energy consumption of WSNs. In this research work, we identified the areas where energy is consumed most in depth based routing techniques. Due to which energy hole may be created. In addition we introduced Receive Signal Strength Indicator (RSSI) based location identification and multilevel power transmission in depth based routing technique. Simulation result shows that the proposed technique gives better results than its counterparts.
Providing an efficient communication for the underwater wireless sensor networks is a significant problem due to the unique characteristics of such environments. Radio signal cannot propagate well in deep water, and we have to replace this with the acoustic channel. This replacement results in many issues like high latency due to less propagation speeds, low bandwidths and high error probability. In addition, new features like node mobility with water currents and 3-dimensional space brings additional challenges to the underwater sensor network (UWSN) protocol design. Many routing protocols have been proposed for such environments but most of them considered that the complete dimensional location of all the sensor nodes is already known through a localization process, which itself is a challenging task in UWSNs. In this paper, we propose a novel routing protocol, called Hop-by-Hop Dynamic Addressing Based (H2-DAB), in order to provide scalable and time efficient routing. Our routing protocol will take advantage of the multiple-sink architecture of the underwater wireless sensor networks. The novelty of H2-DAB is that, it does not require any dimensional location information, or any extra specialized hardware compared to many other routing protocols in the same area. Our results show that H2-DAB effectively achieves the goals of higher data deliveries with optimal delays and energy consumptions.
In this paper, we present a robust, decentralized approach to RF-based location tracking. Our system, called MoteTrack, is
based on low-power radio transceivers coupled with a modest amount of computation and storage capabilities. MoteTrack does
not rely upon any back-end server or network infrastructure: the location of each mobile node is computed using a received
radio signal strength signature from numerous beacon nodes to a database of signatures that is replicated across the beacon
nodes themselves. This design allows the system to function despite significant failures of the radio beacon infrastructure.
In our deployment of MoteTrack, consisting of 23 beacon nodes distributed across our Computer Science building, we achieve
a 50th percentile and 80th percentile location-tracking accuracy of 0.9 and 1.6m respectively. In addition, MoteTrack can
tolerate the failure of up to 60% of the beacon nodes without severely degrading accuracy, making the system suitable for
deployment in highly volatile conditions. We present a detailed analysis of MoteTrack’s performance under a wide range of
conditions, including variance in the number of obstructions, beacon node failure, radio signature perturbations, receiver
sensitivity, and beacon node density.
Energy-efficiency in wireless sensor networks is a very critical design issue, because they usually operate with tiny batteries and take a long time for replacement. In this context, we analyze the optimized scheduling strategy to minimize the energy consumed by data fusion in wireless sensor network. For implementation purpose, a low-complexity fractional-inverse- log scheduling (FILS) algorithm is presented to reduce extra significant amount of energy consumption compared to previously designed protocols. Next, in order to eliminate the communication overhead in centralized scheduling protocols, the simplified distributed fractional-inverse-log scheduling is also provided, which is shown to be very efficient in energy saving especially for a large-scale wireless sensor network. With consideration of the peak power constraint in real circuit design, we update FILS to further constrict the transmission time. Simulation results show that with peak transmission power limitation, energy consumption is still substantially reduced by FILS, and it yields more energy saving for the system with high peak-to-average power ratio (PAPR).
Underwater wireless sensor Networks (UWSN) will provide a variety of attractive working fields such as aquaculture, offshore exploitation, biological monitoring as well as water and seafloor pollution, seismic activity and ocean currents. A practical implementation of these applications will require spreading an important number of nodes to facilitate underwater monitoring by means of data acquiring, so it becomes a challenge to develop simple and reliable modem architectures to reduce both the cost in components and the developing time, still being efficient and robust. Moreover power consumption must be also considered due to energy harvesting difficulties in an underwater environment. This work is focused in the design and implementation of a low cost and energy efficient underwater modem. The paper presents a new acoustic modem design based on an original signal-conditioning model optimally adapted to commercial echo sounder based piezoelectric transducers. It represents a very low-cost solution with a power consumption level similar to current terrestrial wireless sensor networks. The modulation and demodulation algorithms are essential to define the modem architecture. In this work, they have been adapted to a low power microcontroller processing capabilities. The proposed modem architecture includes an 8-bit microcontroller and few external analog components. A binary Coherent-FSK modulation has been chosen because it is more efficient in terms of bandwidth than a non-coherent FSK. Coherent FSK modulation algorithm is quite simple, and can be easily implemented in an 8-bit microcontroller with negligible execution time. Demodulation algorithm is more complex and needs a low-power solution. The paper investigates different alternatives, obtaining a new optimal solution including an additional specific processing unit to the microprocessor core. Compared with previous researches that used microcontrollers, the presented approach also improves energy efficiency -
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without lowering bit rate and bandwidth efficiency. The design has a variable gain reception to measure precisely the incoming signal level and obtaining signal quality indicators similar to RSSI used in wireless RF sensor networks. The circuit has been simulated and experimentally tested too with a prototype. Several tests have been carried out using the different alternatives presented. The goal of the first experiments was to characterize the frequency response of the transducers, and validate acoustic wave generation and amplification models obtained by means of simulation. Measurements were also taken to obtain receiver sensitivity and communication efficiency to power variations. Efficient design of both power amplifier and receiver analog processing stages, combined with optimal microcontroller power saving modes has extended estimated battery. As a conclusion, a worthwhile modem has been designed with the following advantages: Ultra-Low power consumption, a small form factor and a low final cost which enable future low cost deployment of underwater sensor networks.
Underwater sensor networks find applications in oceanographic data collection, pollution monitoring, offshore exploration, disaster prevention, assisted navigation, and tactical surveillance. In this paper, deployment strategies for two-dimensional and three-dimensional communication architectures for underwater acoustic sensor networks are proposed, and a mathematical deployment analysis for both architectures is provided. The objective is to determine the minimum number of sensors to be deployed to achieve optimal sensing and communication coverage, which are dictated by application requirements; provide guidelines on how to choose the optimal deployment surface area, given a target body of water; study the robustness of the sensor network to node failures, and provide an estimate of the number of redundant sensor nodes to be deployed to compensate for potential failures.
In this paper we investigate the problem of uneven energy consumption in a large class of many-to-one sensor networks. In a many-to-one sensor network, all sensor nodes generate constant bit rate (CBR) data and send them to a single sink via multihop transmissions. This type of sensor network has many potential applications such as environmental monitoring and data gathering. Based on the observation that sensor nodes sitting around the sink need to relay more traffic compared to other nodes in outer sub-regions, our analysis verifies that nodes in inner rings suffer much faster energy consumption rates (ECR) and thus have much shorter expected lifetimes. We term this phenomenon of uneven energy consumption rates as the “energy hole” problem, which may result in severe consequences such as early dysfunction of the entire network. We proposed analytical modeling for this problem, which can help understand the relevance of different factors on energy consumption rates. Using this model, we study the effectiveness of several existing approaches towards mitigating the “energy hole” problem, including deployment assistance, traffic compression and aggregation. We have used simulation results to validate our analysis.
Providing scalable and ecient routing services in underwater sensor net- works (UWSNs) is very challenging due to the unique characteristics of UWSNs. Firstly, UWSNs often employ acoustic channels for communications because radio signals do not work well in water. Compared with radio-frequency channels, acous- tic channels feature much lower bandwidths and several orders of magnitudes longer propagation delays. Secondly, UWSNs usually have very dynamic topology as sen- sors move passively with water currents. Some routing protocols have been proposed to address the challenging problem in UWSNs. However, most of them assume that the full-dimensional location information of all sensor nodes in a network is known in prior through a localization process, which is yet another challenging issue to be solved in UWSNs. In this paper, we propose a depth-based routing (DBR) protocol. DBR does not require full-dimensional location information of sensor nodes. Instead, it needs only local depth information, which can be easily obtained with an inex- pensive depth sensor that can be equipped in every underwater sensor node. A key advantage of our protocol is that it can handle network dynamics eciently with- out the assistance of a localization service. Moreover, our routing protocol can take advantage of a multiple-sink underwater sensor network architecture without intro- ducing extra cost. We conduct extensive simulations. The results show that DBR can achieve very high packet delivery ratios (at least 95%) for dense networks with only small communication cost.
In this paper, we present a robust, decentralized approach to RF-based location tracking. Our system, called MoteTrack, is based on low-power radio transceivers coupled with a modest amount of computation and storage capabilities. MoteTrack does not rely upon any back-end server or network infrastructure: the location of each mobile node is computed using a received radio signal strength signature from numerous beacon nodes to a database of signatures that is replicated across the beacon nodes themselves. This design allows the system to function despite significant failures of the radio beacon infrastructure. In our deployment of MoteTrack, consisting of 20 beacon nodes distributed across our Computer Science building, we achieve a 50th
percentile and 80th
percentile location-tracking accuracy of 2 meters and 3 meters respectively. In addition, MoteTrack can tolerate the failure of up to 60% of the beacon nodes without severely degrading accuracy, making the system suitable for deployment in highly volatile conditions. We present a detailed analysis of MoteTrack’s performance under a wide range of conditions, including variance in the number of obstructions, beacon node failure, radio signature perturbations, receiver sensitivity, and beacon node density.
Underwater acoustic networks have the potential to support a large variety of applications, such as mining equipment and environmental monitoring. Although underwater acoustics has been studied for decades, underwater networking and protocol design is just beginning as a research field. One critical tool used for the design and testing of new protocols is a network simulator. For simulators to be useful tools, accurate models of both the channel and the modem need to be implemented. In this paper we present the design and implementation of our interface and channel model for underwater acoustic networks in the ns2 network simulator. We show that the models accurately predict the channel con- ditions and interface costs by comparing them to previously published numerical predictions of channel state. Finally, we present a case study of a protocol designed and simu- lated using our model. Our simulation code is open source and available for general use.
Real-time wireless link reliability estimation is a fundamental building block for self-organization of multihop sensor networks. Observed connectivity at low-power is more chaotic and unpredictable than in wireless LANs, and available resources are severely constrained. We seek estimators that react quickly to large changes, yet are stable, have a small memory footprint and are simple to compute. We create a simple model that generates link loss characteristics similar to empirical traces collected under different contexts. With this model, we simulate a variety of estimators, and uses the simple exponentially weighted moving average (EWMA) estimator, as a basis for comparison. We find that recently propose flip-flop estimators are not superior. However, our cascaded EWMA on windowed averaging is very effective
Various energy and computational constraints for sensor nodes in wireless sensor networks have led to the development of many protocols with emphasis on medium access control (MAC) layer protocols. Several applications have already been envisioned for wireless sensor networks. This paper classifies the existing MAC protocols & the applications/ scenarios for wireless sensor networks. In addition the paper analyses and compares the application specific-ness of the existing Hybrid-MAC protocols depicting the effect of the inefficient behavior of these protocols if imposed on some other applications/ scenarios. Simulation results also verify their application dependency which highlights the need for a generalized, standardized & adaptive MAC protocol suitable for a wider range of applications. The paper concludes with some recommendations for such protocols.
This paper presents a distributed protocol for multi-hop robot positioning in underwater environment without relying on GPS data at each robot. It is a complementary approach for localization and coordination estimations in underwater scenarios where GPS services are unavailable, unstable, or unreliable. The protocol conducts the positioning task in three phases periodically: distance estimating, positioning, and refining. Issues caused by alias problems and measurement errors are discussed and solved in order to improve the practicability of the approach and its accuracy of the location and coordinates estimations. Simulation results comparing to those by the existing work show that our research contributes: (i) a distributed multi-hop positioning algorithm and an associated protocol for underwater multi-hop robot networks; (ii) solutions to two practical issues that increase the practicability of the protocol; and (iii) investigations on relationships between network density, network scale, positionability, and positioning accuracy
A large variety of Autonomous Underwater Vehicles (AUVs) are
currently under development or in production. In order for an AUV to be
useful, its self-navigation capabilities must support the mission
requirements. Often, underwater acoustic navigation techniques must be
utilized in order to meet the navigational accuracy requirements. In
addition to vehicle self-navigation, most AUV operators also require a
method of tracking the vehicle while it is underway, so that its
progress may be monitored, and also so that it may be located easily
upon surfacing, or in the event of a vehicle failure. The Woods Hole
Oceanographic Institution (WHOI) has developed a buoy-based system that
simultaneously provides for both vehicle self-navigation and external
tracking. This system has been used extensively by WHOI to support the
REMUS AUV operations, and has also been used by the Naval Oceanographic
Office to support sea-trials of the LAZARUS vehicle system. Long
Baseline Acoustic Navigation is often the preferred subsea navigation
method. It is generally accomplished by deploying two or more acoustic
transponders, moored to the seafloor, near the desired area of
operations. The vehicle then interrogates the transponders, determines
its range to each, and finds its position using triangulation
techniques. WHOI has developed a radio-controlled buoy, which can serve
as a navigation transponder for the vehicle, and can also be commanded
via the radio link to interrogate the AUV and report the measured travel
time back to the operator. This paper describes the PARADIGM (Portable
Acoustic RADio Geo-referenced Monitoring) system architecture, and
presents data describing results achieved
GIB system: The underwater GPS solution
- bechaz
C. Bechaz and H. Thomas, "GIB system: The underwater GPS solution,"
in Proc. 5th Eur. Conf. Underwater Acoust., 2000, pp. 613-618.