A survey on deployment techniques,localization algorithms,and research challenges for underwater acoustic sensor networks

In recent years, wireless sensor networks (WSNs) have attracted the attention of both the research community and the industry, and this has eventually lead to the widespread use of WSNs in various applications. The significant advancements in WSNs and the advantages brought by WSNs have also enabled the rapid development of underwater acoustic sensor networks (UASNs). In UASNs, in addition to deployment, determining the locations of underwater sensor nodes after they have been deployed is important since it plays a critical role in many applications. Various localization techniques have been proposed for UASNs, and each one is suitable for specific scenarios and has unique challenges. In this paper, after presenting an overview of potential UASN applications, a survey of the deployment techniques and localization algorithms for UASNs has been presented based on their major advantages and disadvantages. Finally, research challenges and open research issues of UASNs have been discussed to provide an insight into future research opportunities.     

UEEDA: Uniform and energy‐efficient deployment algorithm for wireless sensor networks

Efficient and accurate sensor deployment is a critical requirement for the development of wireless sensor networks. Recently, distributed energy‐efficient self‐deployment algorithms, such as the intelligent deployment and clustering algorithm (IDCA) and the distributed self‐spreading algorithm (DSSA), have been proposed to offer almost uniform distribution for sensor deployment by employing a synergistic combination of cluster structuring and a peer‐to‐peer deployment scheme. However, both DSSA and IDCA suffer from unnecessary movements that have arisen from an inappropriate design in partial force. To improve the performance of self‐deployment algorithms, a uniform and energy‐efficient deployment algorithm (UEEDA) is proposed in this paper. Simulation results demonstrate that the proposed UEEDA outperforms both DSSA and IDCA in terms of uniformity and algorithm convergence speed. Copyright © 2007 John Wiley & Sons, Ltd.     

Fault‐tolerant deployment with k‐connectivity and partial k‐connectivity in sensor networks

Wireless sensor networks are prone to failure, so prolonging their lifetime and preventing loss of connectivity are significant. A simple but efficient strategy is to place redundant sensor nodes to establish multi‐connectivity. This paper explores how to add as few as possible nodes (called Steiner nodes) to a sensor network such that the resulting network is k‐connected or partially k‐connected. k‐connectivity means that each pair of the nodes, whether Steiner or original, is connected by at least k node‐disjoint paths, while partial k‐connectivity only requires such connectivity among original nodes. The contribution lies in two aspects. First, the approximation ratio of an existing k‐connectivity repair algorithm is decreased from O(k⁴α) to O(k³α), where α is the approximation ratio of any algorithm that finds a minimum‐weight k‐connected spanning subgraph of a weighted complete graph. This is the best result ever obtained. Second, the first generic partial k‐connectivity repair algorithm is proposed. It is proved that the approximation ratio of this algorithm is at most O(k³α). Copyright © 2008 John Wiley & Sons, Ltd.     

MANCL: a multi‐anchor nodes collaborative localization algorithm for underwater acoustic sensor networks

Localization is an essential and major issue for underwater acoustic sensor networks (UASNs). Almost all the applications in UASNs are closely related to the locations of sensors. In this paper, we propose a multi‐anchor nodes collaborative localization (MANCL) algorithm, a three‐dimensional (3D) localization scheme using anchor nodes and upgrade anchor nodes within two hops for UASNs. The MANCL algorithm divides the whole localization process into four sub‐processes: unknown node localization process, iterative location estimation process, improved 3D Euclidean distance estimation process, and 3D DV‐hop distance estimation process based on two‐hop anchor nodes. In the third sub‐process, we propose a communication mechanism and a vote mechanism to determine the temporary coordinates of unknown nodes. In the fourth sub‐process, we use two‐hop anchor nodes to help localize unknown nodes. We also evaluate and compare the proposed algorithm with a large‐scale localization algorithm through simulations. Results show that the proposed MANCL algorithm can perform better with regard to localization ratio, average localization error, and energy consumption in UASNs. Copyright © 2014 John Wiley & Sons, Ltd.     

LRP: Link quality‐aware queue‐based spectral clustering routing protocol for underwater acoustic sensor networks

Recently, underwater acoustic sensor networks (UASNs) have been considered as a promising approach for monitoring and exploring the oceans in lieu of traditional underwater wireline instruments. As a result, a broad range of applications exists ranging from oil industry to aquaculture and includes oceanographic data collection, disaster prevention, offshore exploration, assisted navigation, tactical surveillance, and pollution monitoring. However, the unique characteristics of underwater acoustic communication channels, such as high bit error rate, limited bandwidth, and variable delay, lead to a large number of packet drops, low throughput, and significant waste of energy because of packets retransmission in these applications. Hence, designing an efficient and reliable data communication protocol between sensor nodes and the sink is crucial for successful data transmission in underwater applications. Accordingly, this paper is intended to introduce a novel nature‐inspired evolutionary link quality‐aware queue‐based spectral clustering routing protocol for UASN‐based underwater applications. Because of its distributed nature, link quality‐aware queue‐based spectral clustering routing protocol successfully distributes network data traffic load evenly in harsh underwater environments and avoids hotspot problems that occur near the sink. In addition, because of its double check mechanism for signal to noise ratio and Euclidean distance, it adopts opportunistically and provides reliable dynamic cluster‐based routing architecture in the entire network. To sum up, the proposed approach successfully finds the best forwarding relay node for data transmission and avoids path loops and packet losses in both sparse and densely deployed UASNs. Our experimental results obtained in a set of extensive simulation studies verify that the proposed protocol performs better than the existing routing protocols in terms of data delivery ratio, overall network throughput, end‐to‐end delay, and energy efficiency.     

Beacon‐based routing protocols for underwater acoustic sensor networks

Underwater Acoustic Sensor Networks (UW‐ASN) are provisioned with limited bandwidth, long variable propagation delay, limited available energy, highly unreliable acoustic channels, and random node mobility. Consequently, efficient data routing between source destination pair requires UW‐ASN to apply a technology different than terrestrial networks. For the past few years researchers have proposed many robust and efficient routing protocols for UW‐ASN, thus reviewing the challenges posed by stringent underwater environment. These protocols can be broadly categorized into localization based and localization‐free protocols. This paper presents a critical review of beacon‐based localization‐free routing protocols and suggest possible solution to improve the working of studied beacon based protocols. This work categorizes beacon based protocols into hop‐by‐hop, end‐to‐end, single, and multiple parameters based forwarding protocols. This categorization will help to differentiate and identify the requirements for the development of new beacon‐based protocols. Finally, this paper presents performance comparison based on simulation results and outlines the research gap and future directions.     

Routing design avoiding energy holes in underwater acoustic sensor networks

Interest in underwater acoustic sensor networks (UW‐ASNs) has rapidly increased with the desire to control the large portion of the world covered by oceans. Energy efficiency is one of the major concerns in UW‐ASNs due to the limited energy budget of the underwater sensor nodes. In this paper, we tackle the problem of energy holes in UW‐ASNs while taking into consideration the unique characteristics of the underwater channel. We prove that we can evenly distribute the transmission load among sensor nodes provided that sensors adjust their communication range when they send or forward the periodically generated data. In particular, we propose a balanced routing strategy along with the associated deployment pattern that meticulously determines the load weight for each possible next hop that leads to fair energy consumption among all underwater sensors. Consequently, the energy holes problem is overcome, and hence, the network lifetime is improved. To the best of our knowledge, this is the first work that addresses the energy hole problem in UW‐ASNs. Copyright © 2016 John Wiley & Sons, Ltd.     

无线传感网规则拓扑结构的部署与设计综述

在无线传感网应用中部署规则拓扑结构能实现感知区域的完全覆盖和采集点的精确定位,以较小的部署代价提供更好的网络性能,为无线传感网的优化设计提供参照依据,对规则拓扑结构的相关研究进行综述。基于节点有效面积这个指标,探讨了完全覆盖、k-覆盖、l-连通情况下的拓扑部署方式与效能,并从连通性、能耗、传输性能、路由方案和MAC协议等方面总结了典型规则拓扑结构的性能、变化规律和适用范围。指出了各结构的最佳适用条件,并提出了若干有待进一步研究的方向。     

An energy‐efficient asynchronous wake‐up scheme for underwater acoustic sensor networks

In addition to the requirements of the terrestrial sensor network where performance metrics such as throughput and packet delivery delay are often emphasized, energy efficiency becomes an even more significant and challenging issue in underwater acoustic sensor networks, especially when long‐term deployment is required. In this paper, we tackle the problem of energy conservation in underwater acoustic sensor networks for long‐term marine monitoring applications. We propose an asynchronous wake‐up scheme based on combinatorial designs to minimize the working duty cycle of sensor nodes. We prove that network connectivity can be properly maintained using such a design even with a reduced duty cycle. We study the utilization ratio of the sink node and the scalability of the network using multiple sink nodes. Simulation results show that the proposed asynchronous wake‐up scheme can effectively reduce the energy consumption for idle listening and can outperform other cyclic difference set‐based wake‐up schemes. More significantly, high performance is achieved without sacrificing network connectivity. Copyright © 2015 John Wiley & Sons, Ltd.     

Oceanic forces and their impact on the performance of mobile underwater acoustic sensor networks

This paper focuses on the performance analysis of Underwater Wireless Acoustic Sensor Networks (UWASNs) with passively mobile sensor nodes moving because of the influence of major oceanic forces. In an UWASN, passive node mobility is inevitable. Therefore, the performance analysis of UWASNs renders meaningful insights with the inclusion of a mobility model, which represents realistic oceanic scenarios. In this regard, the existing works on performance analysis of UWASNs lack the consideration of major dominating forces, which offer impetus for a node's mobility. Additionally, the existing works are limited to only shallow depths and coastal areas. Therefore, in this paper, we have proposed a physical mobility model, named Oceanic Forces Mobility Model , by incorporating important realistic oceanic forces imparted on nodes. The proposed model considers the effects of node mobility in 3‐D space of water. We also present an analysis on the impact of node mobility on the performance of UWASNs in terms of network dispersion and localization. Simulation results indicate performance degradation of UWASNs in the presence of oceanic forces—localization coverage decreases by 36.70% , localization error increases nearly by 21.14% , and average energy consumption increases by 3% approximately. Copyright © 2014 John Wiley & Sons, Ltd.     

一种节省能量的水声传感器网络组织结构与协议

本文为水声传感器网络提出了一种基于簇间协商的事件报告策略,网络节点以簇的形式组织起来,多址接入协议采用了一种适合水声环境的TDMA/CDMA混合式协议,建立了由簇头与网关组成的用于簇间通信的主干链路。仿真结果表明,基于簇间协商的事件报告策略能有效减少网络中的冗余通信量从而延长网络寿命。     

Graph‐based optimal asynchronous scheduling in large propagation delay underwater acoustic sensor networks

Optimal scheduling is essential to minimize the time wastage and maximize throughput in high propagation delay networks such as in underwater and satellite communication. Understanding the drawbacks of synchronous scheduling, this paper addresses an asynchronous optimal scheduling problem to minimize the time wastage during the transmission. The proposed scheduling problem is analyzed in both broadcast and non‐broadcast networks, which is highly applicable in high propagation delay networks. In broadcast networks, the proposed scheduling method reduces to a graph‐theoretic model that is shown to be equivalent to the classic algorithmic asymmetric traveling salesman problem (TSP) which is NP‐Hard. Although it is NP‐Hard, the TSP is well‐investigated with many available methods to find the best solution for up to tens of thousands of nodes. In non‐broadcast networks, the optimal solution to the scheduling problem considers the possibility of parallel transmission, which is optimized using graph coloring algorithm. The groups obtained through graph coloring are solved using Asymmetric Traveling Salesman algorithm to obtain the optimal schedule. The proposed method efficiently solves the scheduling problem for networks of practical size.     

QoS‐aware target coverage in wireless sensor networks

Wireless sensor networks have emerged recently as an effective way of monitoring remote or inhospitable physical targets, which usually have different quality of service (QoS) constraints, i.e., different targets may need different sensing quality in terms of the number of transducers, sampling rate, etc. In this paper, we address the problem of optimizing network lifetime while capturing those diversified QoS coverage constraints in such surveillance sensor networks. We show that this problem belongs to NP‐complete class. We define a subset of sensors meeting QoS requirements as a coverage pattern, and if the full set of coverage patterns is given, we can mathematically formulate the problem. Directly solving this formulation however is difficult since number of coverage patterns may be exponential to number of sensors and targets. Hence, a column generation (CG)‐based approach is proposed to decompose the original formulation into two subproblems and solve them iteratively. Here a column corresponds to a feasible coverage pattern, and the idea is to find a column with steepest ascent in lifetime, based on which we iteratively search for the maximum lifetime solution. An initial feasible set of patterns is generated through a novel random selection algorithm (RSA), in order to launch our approach. Experimental data demonstrate that the proposed CG‐based approach is an efficient solution, even in a harsh environment. Simulation results also reveal the impact of different network parameters on network lifetime, giving certain guidance on designing and maintaining such surveillance sensor networks. Copyright © 2009 John Wiley & Sons, Ltd.     

Deterministic deployment based on information coverage in wireless sensor networks

In this study, a deterministic deployment problem in wireless sensor networks is examined. On the basis of information coverage, we study equilateral triangle and square deployment strategies, and we provide the maximum distance between sensors in order to reach the required detection probability for any point in the monitoring field. First, we provide a model of the signal attenuation. On the basis of the detected signal from the K sensors, the best linear and unbiased estimation is used to estimate the signal parameter with the corresponding error. For the equilateral triangle deployment, the maximum distance between sensors is computed and provided when the received signal data from two or three sensors is used. Similarly, we have computed and supplied the maximum distance between sensors in the square deployment. Simulations are performed to show the relationship between the number of sensors and the detection probability. The simulation results show that it is not a good choice to improve the detection probability with a larger number of sensors.Copyright © 2012 John Wiley & Sons, Ltd.     

Sparse deployment scheme in mobile sensor networks with prioritized event area

Sensor deployment is a fundamental issue in Internet of things. In this paper, It addressed the problem of how to effective deployment for prioritized event area in mobile sensor networks with low density sensors, which coverage completely cannot be realized. When event areas have been detected, the problem how to make mobile nodes moved to a suitable place with effective deployment is studied. Firstly, a coverage weight by priority function of event area is defined. It deduced conclusion that coverage effectiveness have maximization as if all of nodes coverage weight are identical. A nodes deployed strategy have presented that combined coverage weight and virtual force. Finally, some simulations shown that the proposed deployment algorithm are accurate and effective. Copyright © 2015 John Wiley & Sons, Ltd.     

一种用于水声传感网的MAC层协议

针对分簇的水声传感网,提出了一种基于时分多址（TDMA）的MAC层协议——Cluster-TDMA。该协议主要由规划阶段和传输阶段组成。规划阶段,首先由网关节点规划能造成簇间干扰的子节点的传输,其次由各簇头节点分别规划本簇内其他子节点的传输;传输阶段,子节点根据规划表周期性地向簇头节点发送数据,这些数据最终汇聚到网关节点。该协议简单有效地解决了引起簇间干扰子结点的传输规划问题。C++仿真实验表明,该协议具有良好的吞吐率和能量效率性能。     

Static wireless sensor networks deployment using an improved binary PSO

A major issue in designing wireless sensor networks is the deployment problem. Indeed, many performances of the sensor network, such as coverage, are determined by the number and locations of deployed sensors. This paper reviews existing deterministic deployment strategies and devises a modified binary particle swarm optimization, which adopts a new position updating procedure for a faster convergence and exploits the abandonment concept to avoid some drawbacks such as premature convergence. The devised approach combines, in a meaningful way, the characteristics of the binary particle swarm optimization with the wireless sensor networks deployment requirements in order to devise a lightweight and efficient sensor placement algorithm. The effectiveness and efficiency of the proposed approach are evaluated through extensive simulations. The obtained results show that the proposed algorithm outperforms the state‐of‐the‐art approaches, especially in the case of preferential coverage. Copyright © 2015 John Wiley & Sons, Ltd.     

Coverage and connectivity aware critical target monitoring for wireless sensor networks: Novel NSGA‐II–based approach

As sensor nodes have limited sensing and transmission capability, their efficient deployment takes an important role in proper monitoring of the critical targets in various applications of wireless sensor networks (WSNs). The key issues that need to be taken care during deployment are the lesser number of deployed sensors, coverage of the targets, and connectivity between the sensor nodes. In this paper, we have proposed NSGA‐II with modified dominance to solve the node deployment problem with the aforementioned three conflicting objectives. The conventional domination method is modified for better performance of the NSGA‐II. An intelligent representation of chromosome is provided. Three conflicting objectives are derived to evaluate the chromosomes. Extensive simulation on the proposed algorithm and the statistical test, and analysis of variance (ANOVA) followed by post hoc analysis are performed.     

Performance analysis of distributed underwater wireless acoustic sensor networks systems in the presence of internal solitons

In this paper, we have analyzed the performance of distributed Underwater Wireless Acoustic Sensor Networks (UWASNs) in the presence of internal solitons in the ocean. Internal waves commonly occur in a layered oceanic environment having differential medium density. So, in a layered shallow oceanic region, the inclusion of the effect of internal solitons on the performance of the network is important. Based on various observations, it is proved that nonlinear internal waves, that is, solitons are one of the major scatterers of underwater sound. If sensor nodes are deployed in such type of environment, internode communication is affected because of the interaction of wireless acoustic signal with these solitons, as a result of which network performance is greatly affected. We have evaluated the performance of UWASNs in the 3‐D deployment scenario of nodes, in which source nodes are deployed in the ocean floor. In this paper, four performance metrics, namely, Signal‐to‐interference‐plus‐noise‐ratio (SINR), bit error rate (BER), Delay (DELAY), and energy consumption are introduced to assess the performance of UWASNs. Simulation studies show that in the presence of internal solitons, SINR decreases by approximately 10%, BER increases by 17%, delay increases by 0.24%, and energy consumption per node increases by 53.05%, approximately. Copyright © 2014 John Wiley & Sons, Ltd.     

Localization under anchor node uncertainty for underwater acoustic sensor networks

This paper deals with the problem of sensor node localization in the presence of uncertainty in anchor node location. Aqueous environments are prone to adverse effects of underwater currents. This adversity causes non‐negligible mobility to the anchor nodes deployed under water. Localization in the presence of uncertainty in the anchor node location is quite challenging. Also, the authors consider the ray‐bending property of underwater medium due to depth dependent sound speed, to furnish the accurate position estimate of the target node. Standard ray equations are used to model the path followed by acoustic rays in water. Maximum likelihood estimation is proposed to estimate the location of target node with uncertainty in anchor node positions and is compared with the scheme with exact knowledge of anchor node positions, and the results are reported. Monte Carlo simulation is used to assess the performance of the proposed method. Also, the Cramer‐Rao lower bound with uncertainty in anchor nodes is derived and described. Simulation results of the proposed algorithm outperform the existing algorithm with known anchor location by up to 49.4%, and hence, accuracy is improved in the proposed method.