A Review and Analysis of Localization Techniques in Underwater Wireless Sensor Networks

In recent years,there has been a rapid growth in Underwater Wireless Sensor Networks(UWSNs).The focus of research in this area is now on solving the problems associated with large-scale UWSN.One of the major issues in such a network is the localization of underwater nodes.Localization is required for tracking objects and detecting the target.It is also considered tagging of data where sensed contents are not found of any use without localization.This is useless for application until the position of sensed content is confirmed.This article’s major goal is to review and analyze underwater node localization to solve the localization issues in UWSN.The present paper describes various existing localization schemes and broadly categorizes these schemes as Centralized and Distributed localization schemes underwater.Also,a detailed subdivision of these localization schemes is given.Further,these localization schemes are compared from different perspectives.The detailed analysis of these schemes in terms of certain performance metrics has been discussed in this paper.At the end,the paper addresses several future directions for potential research in improving localization problems of UWSN.

Dynamic Coverage with Wireless Sensor and Actor Networks in Underwater Environment

This paper studies the problem of dynamic coverage with wireless sensor and actor networks(WSANs) in underwater environment.Different from most existing works,the WSANs consist of two kinds of nodes,i.e.,sensor nodes(SNs) which cannot move autonomously and actor nodes(ANs) which can move autonomously according to the performance requirement.The problem of how to coordinate two kinds of nodes to facilitate dynamic coverage in underwater environment is challenging due to their heterogeneous capabilities.To reduce redundancy of communication links and improve connectivity between ANs and SNs in underwater WSANs,a min-weighted rigid graph based topology optimization scheme is first developed,such that the underwater communication energy consumption can be saved.With the optimized topology,a dynamic coverage strategy is proposed to improve the coverage among SNs and ANs for underwater WSAN where underwater fluid motions are considered.Furthermore,it is proved that the network coverage area is connected by using the min-weighted rigid graph.Finally,simulation results are presented to show the effectiveness of the main results.

Capacity Research in Cluster-Based Underwater Wireless Sensor Networks Based on Stochastic Geometry

Underwater wireless sensor networks(UWSNs) have attracted wide attention in recent years.The capacity research on it is still in the initial stage,lacking adequate performance evaluation for network construction.This paper will focus on this subject by theoretical analysis and simulation,aiming to provide some insights for the actual UWSNs construction.According to the structure features of cluster-based UWSNs and the propagation characteristics of underwater acoustic signal,with the combination of signal to interference plus noise ratio,we define some capacity performance metrics,such as outage probability and transmission capacity.Based on the theory of stochastic geometry,a network capacity analytical model used in the cluster-based UWSNs is presented.The simulation results verify the validity of the theoretical analysis,and the cause of error between theoretical and simulation results has also been clearly explained.

A New Method to Improve Performance of Cooperative Underwater Acoustic Wireless Sensor Networks via Frequency Controlled Transmission Based on Length of Data Links

In this paper a new method to improve performance of cooperative underwater acoustic (UWA) sensor networks will be introduced. The method is based on controlling and optimizing carrier frequencies which are used in data links between network nods. In UWA channels Pathloss and noise power spectrum density (psd) are related to carrier frequency. Therefore, unlike radio communications, in UWA Communications signal to noise ratio (SNR) is related to frequency besides propagation link length. In such channels an optimum frequency in whole frequency band and link lengths cannot be found. In Cooperative transmission, transmitter sends one copy of transmitted data packets to relay node. Then relay depending on cooperation scheme, amplifies or decodes each data packet and retransmit it to destination. Receiver uses and combines both received signals to estimate transmitted data. This paper wants to propose a new method to decrease network power consumptions by controlling and sub-optimizing transmission frequency based on link length. For this purpose, underwater channel parameters is simulated and analyzed in 1km to 10km lengths (midrange channel). Then link lengths sub categorized and in each category, optimum frequency is computed. With these sub optimum frequencies, sensors and base station can adaptively control their carrier frequencies based on link length and decrease network’s power consumptions. Finally Different Cooperative transmission schemes “Decode and Forward (DF)” and “Amplify and Forward (AF)”, are simulated in UWA wireless Sensor network with and without the new method. In receiver maximum ratio combiner (MRC) is used to combining received signals and making data estimations. Simulations show that the new method, called AFC cooperative UWA communication, can improve performance of underwater acoustic wireless sensor networks up to 40.14%.

A synchronous duty-cycled reservation based MAC protocol for underwater wireless sensor networks

To design an energy-efficient Medium Access Control(MAC)protocol for the Underwater Wireless Sensor Networks(UWSNs)is an urgent research issue since depleted batteries cannot be recharged or replaced in the underwater environment.Moreover,the underwater acoustic channels are affected by hindrances such as long propagation delay and limited bandwidth,which appear in the design of the MAC protocol for the UWSNs.The available MAC protocols for the terrestrial wireless sensor networks exhibit low performance in energy efficiency,throughput and reliability in the UWSNs,and cannot be used in the UWSNs directly because of their unique characteristics.This paper proposes a synchronous duty-cycled reservation-based MAC protocol named Ordered Contention MAC(OCMAC)protocol.The basic mechanism of this protocol is to schedule data transmission by transmitters through the scheduling of Ready To Send(RTS)frames.The protocol eliminates the possible collision during data transmission and improves communication efficiency.The paper analyzes the performance in energy efficiency,throughput and reliability of the protocol by modeling the queuing behavior of OCMAC with a Markov Chain process.Furthermore,the analytical model is validated through a simulation study.The analysis results demonstrated that while providing good throughput and reliability,OCMAC can achieve energy saving.

A Void Avoidance Scheme for Grid-Based Multipath Routing in Underwater Wireless Sensor Networks

This work proposes a geographic routing protocol for UWSNs based on the construction of a 3D virtual grid structure, called Void-Avoidance Grid-based Multipath Position-based Routing (VA-GMPR). It consists of two main components, the multipath routing scheme and the grid-based void avoidance (GVA) mechanism for handling routing holes. The multipath routing scheme adopts node-disjoint routes from the source to the sink in order to enhance network reliability and load balancing. While the GVA mechanism handles the problem of holes in 3D virtual grid structure based on three techniques: Hole bypass, path diversion, and path backtracking. The performance evaluation of the VA-GMPR protocol was compared to a recently proposed grid-based routing protocol for UWSNs, called Energy-efficient Multipath Geographic Grid-based Routing (EMGGR). The results showed that the VA-GMPR protocol outperformed the EMGGR protocol in terms of packet delivery ratio, and end-to end-delay. However, the results also showed that the VA-GMPR protocol exhibited higher energy consumption compared to EMGGR.

Hierarchical self-localization of underwater wireless sensor network nodes

The follow-up application of underwater wireless sensor network is influenced by accuracy of self-localization of nodes. The self-localization of nodes is discussed in this paper. First of all, nodes of underwater wireless sensor network are classified into several levels according to the accuracy of position of nodes and the levels are from the first to the fifth in accordance with accuracy of nodes from high to low respectively. Secondly, the level of anchor nodes can be known by those unknown nodes from the information given by the anchor nodes themselves, At the same time the unknown nodes are able to be located in the area controlled by the first level of anchor nodes that are as the aggregation. Then the positioning algorithm is designed correspondingly in accordance with the accuracy level of nodes. Finally, the positioning algorithm is simulated and analyzed. The result shows that the unknown nodes can be located effectively by hierarchical control.

Cooperative Nodes Localization for Three-Dimensional Underwater Wireless Sensor Network Based on Weighted Centroid Localization Algorithm

The underwater wireless sensor network(UWSN) has the features of mobility by drifting,less beacon nodes,longer time for localization and more energy consumption than the terrestrial sensor networks,which makes it more difficult to locate the nodes in marine environment.Aiming at the characteristics of UWSN,a kind of cooperative range-free localization method based on weighted centroid localization(WCL) algorithm for three-dimensional UWSN is proposed.The algorithm assigns the cooperative weights for the beacon nodes according to the received acoustic signal strength,and uses the located unknown nodes as the new beacon nodes to locate the other unknown nodes,so a fast localization can be achieved for the whole sensor networks.Simulation results indicate this method has higher localization accuracy than the centroid localization algorithm,and it needs less beacon nodes and achieves higher rate of effective localization.

A Comparative Assessment of Floating and Submerged Sensor Network Deployments for Monitoring Underwater Sediment Transport Processes

Wireless Sensor Networks (WSNs) are a pioneering technology in many environmental monitoring applications owing to their ability to be deployed for long periods of time in locations that cannot be reached manually. One such use-case is the monitoring of underwater sediment transport, a process that plays a significant role in coastal erosion. Previous examples of WSNs deployed for this purpose have been in the form of underwater sensor networks (UWSNs), which have a number of shortcomings from both a practical and technical viewpoint. As such, this paper provides a comparative assessment of UWSNs and an alternative deployment approach of floating echo- sounding sensor networks for the purpose of monitoring underwater sediment transport.

Study of Wireless Sensor Network Based on Optical Communication:Research Challenges and Current Results

With the rapid developments of commercial demands,a majority of ad­vanced researches have been investigated for the applications of underwa­ter wireless sensor(WSN)networks.Recently optical communication has been considered for underwater wireless sensor network.An experimental set-up for testing optical communication underwater has been provided and designed in present papers to maximize the energy coupled from these displacements to the transduction mechanism that converts the mechanical energy into electrical.The true case has been considered by measuring dif­fuse attenuation coefficients in different seas.One stand out potential opti­cal communication method,Visible Light Communication(VLC)has been talked and several communication methods are compared from many points of view,for example attenuation in salt water.The evaluation of modula­tion techniques for underwater wireless optical communications has been displayed,and further how the data collection and storage with an under­water WSN is introduced.In this paper current researches for an(UWSN)based on optical communication are studied,in particular the potential VLC method and comparisons of VLC with other optical communication approaches.Underwater challenges would be analyzed by comparing a sort of communication methods,applied in underwater.Future work will be de­veloped at last.

Mutual-information based weighted fusion for target tracking in underwater wireless sensor networks

Underwater wireless sensor networks(UWSNs)can provide a promising solution to underwater target tracking.Due to limited energy and bandwidth resources,only a small number of nodes are selected to track a target at each interval.Because all measurements are fused together to provide information in a fusion center,fusion weights of all selected nodes may affect the performance of target tracking.As far as we know,almost all existing tracking schemes neglect this problem.We study a weighted fusion scheme for target tracking in UWSNs.First,because the mutual information(MI)between a node’s measurement and the target state can quantify target information provided by the node,it is calculated to determine proper fusion weights.Second,we design a novel multi-sensor weighted particle filter(MSWPF)using fusion weights determined by MI.Third,we present a local node selection scheme based on posterior Cramer-Rao lower bound(PCRLB)to improve tracking efficiency.Finally,simulation results are presented to verify the performance improvement of our scheme with proper fusion weights.

考虑锚节点位置不确定的水下目标定位算法研究

考虑时钟异步和声波分层效应的影响,该文研究了当测量过程受到未知噪声干扰,且锚节点位置不确定时水下目标节点的定位问题。首先构造了水下节点间飞行时间模型,设计了一种交互式异步通信协议,建立了最小化定位误差的优化目标函数。然后提出了一种基于深度强化学习的水下目标定位算法,并采用层归一化来改进深度神经网络,进一步提高模型的泛化能力。最后,仿真和实验结果验证所提方法的有效性。

基于REPBR跳数效用转发的改进路由算法

针对基于压力的水下无线传感器网络路由协议数据包传输路径距离过长、能量消耗不均衡等问题,提出一种基于REPBR跳数效用转发的改进路由算法。采用一种效用函数策略即加入剩余能量、节点间的跳数和链路质量3种因子解决能量消耗不均衡的问题,引入最小跳数算法获取节点到sink节点的跳数值,在数据包转发阶段综合比较路由效益选择最佳转发节点。仿真结果表明,改进后算法相比REPBR、EEDBR、DBR有较小的网络时延,提升了数据包的转发效率,提高了网络性能。

基于生成对抗网络的UWSNs恶意节点检测方法

水下无线传感器网络(Underwater Wireless Sensor Networks,UWSNs)节点通常部署于无人值守的恶劣环境中,恶意节点的存在对网络的安全构成了极大威胁。为了在缺乏节点行为证据的情况下有效检测恶意节点,提出了一种基于生成对抗网络(Generative Adversarial Network,GAN)的恶意节点检测方法。首先,构建了基于GAN的异常预测模型;其次,收集数据、链路、能量等多维信任证据,构建出训练数据集;最后,训练异常预测模型,并通过信任决策检测恶意节点。仿真结果表明,该方法可以在不需要大量信任证据的情况下有效地进行恶意节点检测,并且与同类型方法相比,所提方法具有较高的恶意节点检测率、通信成功率及较低的假阳率。

水下无线传感器网络自适应锥体矢量路由协议

水声传感器网络(Underwater Acoustic Wireless Sensor Networks,UWSNs)由于复杂的水下环境,面临着投递率低、传播延迟高和节点能耗大等挑战。为解决这些问题,文章提出了一种自适应锥体矢量路由协议(Adaptive Cone Vector Routing Protocol,ACVRP),根据节点密度自适应调整锥体区域大小和方向,减少冗余通信和网络能耗,并根据节点的剩余能量和节点在锥体区域中的位置确定节点转发优先级,以提高投递率、减少传输跳数。仿真实验结果显示,与VBF、AHH-VBF和AHHC-VBF相比,ACVRP在包投递率、能效和端到端延迟方面均表现更佳。

一种能量均衡的水下无线传感器网络覆盖空洞修补方法

针对现有水下无线传感器网络空洞修补方法需要空洞边界探测、通信和计算开销大、覆盖率和能量均衡性差、水下环境模型过于理想化等问题,考虑水底地形复杂,且通常存在较大障碍物等环境因素,建立了基于能量的节点之间、区域边界、零能量空洞、低能量覆盖洞、水底地形及障碍物作用力等多维度的虚拟力模型,提出了基于上述虚拟力模型和能量均衡的空洞修补算法。该算法不需要精确的空洞边界探测,对水下复杂地形和不同环境具有良好的适应性和鲁棒性。此外,提出的对低能量节点、低能量覆盖洞冗余修补的策略,显著提高了修补后网络能量分布的均衡性,减少了因低能量节点的能量很快耗尽而出现新的覆盖空洞的频率,减少了空洞修补频次,降低了网络维护成本。

基于改进的鲸鱼优化迭代算法的水下传感器网络节点定位方法

针对水下无线传感器网络中锚节点较少、迭代误差大导致节点定位精度低的问题,文章提出了一种基于改进的鲸鱼优化-牛顿迭代的水下三维节点定位算法(Improved Whale Optimization-Newton Iteration,IWONI)。该算法首先使用牛顿迭代算法对节点距离远近关系建立对应法则,并利用目标位置估计值和修正因子为改进的鲸鱼优化算法提供动态搜索区域;其次,建立以测量误差为权重的适应度函数作为判断基准,采用改进的鲸鱼优化算法进行迭代求解,以获得最优解;最后,利用定位方程得到网络节点位置。为了验证IWONI算法的性能,将IWONI算法与时间差定位算法(TDOA-CHAN、TDOA-Taylor)、测距定位算法(最小二乘法、高斯牛顿迭代法)和牛顿迭代算法进行定位误差、收敛性能和定位成功率对比实验,并验证了节点数量对定位精度的影响。实验结果表明:(1)IWONI算法的定位误差和收敛速度明显优于其他对比算法。(2)IWONI算法在测量噪声大时的定位成功率高达92%,明显优于其他对比算法。(3)在通信半径不变的情况下,选择5~7个传感器节点可以在IWONI算法中实现定位精度与成本开销的平衡。

一种在线迭代的水下随机传感器阵列生成算法

水下攻防对抗体系逐渐向无人化、网络化发展。为降低水声通信对水下传感器网探测能力的制约,首先分析了水下通信方式的应用特点,提出了水下随机传感器分布式阵列通信方式应用方案。然后结合凝聚式分类技术,建立距离矩阵和通信关系矩阵,提出了一种基于通信距离的在线迭代阵列生成算法,并给出了算法流程和计算实例。最后通过仿真试验验证了算法的有效性,并与规则阵列进行了对比分析。

水下无线传感器网络抗恶意干扰技术应用及研究进展

水下无线传感器网络(UWSNs)越来越广泛地应用于海洋开发等领域,但其水声通信信道的开放性导致UWSNs容易受到水下的各类恶意干扰,各类通信抗干扰技术可有效提高UWSNs的通信可靠性。文中首先介绍了通信抗干扰技术的发展历程及其国内外发展现状,并对通信抗干扰技术的发展规律进行分析;其次分析了UWSNs中通信抗干扰的关键技术以及技术需求,最后对UWSNs通信抗干扰技术的发展应用进行了展望。

基于改进联合概率数据关联的AUV定位算法

基于水下无线传感器网络的位置估计是解决水下自主机器人定位问题的有效方法,然而由于水下无线传感器网络中的传感器节点一般部署在开放水域中,外来的恶意节点在基于到达时间的网络信道中注入恶意噪声延迟会对定位精度产生不利影响。针对这个问题,本文提出了一种改进联合概率数据关联算法。首先,我们考虑了一种异构的网络架构,包括水面浮标节点、水下信标节点和待定位的AUV目标节点,并获取网络架构中信标节点和AUV之间的距离测量;然后,我们设计了一种基于矩阵相似度的恶意噪声识别机制,识别并丢弃受恶意噪声污染的距离测量,并且对检测为未受到恶意噪声污染的距离测量进行分组,利用最小二乘法完成对AUV的初步定位;接着,为了丰富所得到的样本测量点以提高AUV的定位精度,我们在预测点以及检测出未受到恶意噪声污染的测量点的附近生成一系列服从高斯分布的虚拟测量;最后,对这些测量点进行数据关联处理与更新,完成对AUV目标节点的精确定位。仿真结果表明,所提出的定位方法与其他工作相比,在有恶意噪声攻击的情况下仍能保持较好的定位精度。