Wireless Information and Power Transfer in Underwater Acoustic Sensor Networks

Wireless information and power transfer(WIPT) enables simultaneously communications and sustainable power supplement without the erection of power supply lines and the replacement operation of the batteries for the terminals. The application of WIPT to the underwater acoustic sensor networks(UWASNs) not only retains the long range communication capabilities, but also provides an auxiliary and convenient energy supplement way for the terminal sensors, and thus is a promising scheme to solve the energy-limited problem for the UWASNs. In this paper, we propose the integration of WIPT into the UWASNs and provide an overview on various enabling techniques for the WIPT based UWASNs(WIPT-UWASNs) as well as pointing out future research challenges and opportunities for WIPT-UWASNs.

A Survey on Underwater Acoustic Sensor Networks: Perspectives on Protocol Design for Signaling, MAC and Routing

Underwater acoustic sensor networks (UASNs) are often used for environmental and industrial sensing in undersea/ocean space, therefore, these networks are also named underwater wireless sensor networks (UWSNs). Underwater sensor networks are different from other sensor networks due to the acoustic channel used in their physical layer, thus we should discuss about the specific features of these underwater networks such as acoustic channel modeling and protocol design for different layers of open system interconnection (OSI) model. Each node of these networks as a sensor needs to exchange data with other nodes;however, complexity of the acoustic channel makes some challenges in practice, especially when we are designing the network protocols. Therefore based on the mentioned cases, we are going to review general issues of the design of an UASN in this paper. In this regard, we firstly describe the network architecture for a typical 3D UASN, then we review the characteristics of the acoustic channel and the corresponding challenges of it and finally, we discuss about the different layers e.g. MAC protocols, routing protocols, and signal processing for the application layer of UASNs.

Data Concurrent Transmission MAC Protocol for Application Oriented Underwater Acoustic Sensor Networks

With the increasing demand for marine exploration, underwater acoustic sensor networks (UASNs) are prone to have the characteristics of large-scale, long term monitoring, and high data traffic load. Underwater media access control (MAC) protocols, which allow multiple users to share the common medium fairly and efficiently, are essential for the performance of UASNs. However, the design of MAC protocols is confronted with the challenges of spatial unfairness, data eruption, and low energy efficiency. In this paper, we propose a novel data concurrent transmission (DCT) MAC protocol, which is able to exploit long propagation delay and conduct concurrent transmission. Specifically, we present the theoretical performance analysis of the proposed MAC protocol in detail and give an analytical solution of the success concurrent transmission probability between nodes. In addition, simulation results are provided to demonstrate that our proposed protocol is appropriate for UASNs and can significantly improve the performance in terms of network throughput and energy consumption. Finally, we give some typical future applications of UASNs and discuss the demands on MAC protocol design.

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 Cooperative Jamming Scheme Based on Node Authentication for Underwater Acoustic Sensor Networks

Cooperative jamming(CJ)is one of the important methods to solve security problems of underwater acoustic sensor networks(UASNs).In this paper,we propose a Cooperative Jamming Scheme based on Node Authentication for UASNs to improve the effect of CJ by selecting suitable jamming source for found illegal nodes.In the node authentication,all nodes will be identified by their trust value(TV).TV is calculated according to three types of evidence:channel-based trust evidence,behavior-based trust evidence and energy-based trust evidence.Besides,to deal with cases where legal nodes may be suspected,the historical TV and trust redemption will be considered when calculating TV.In cooperative jamming,according to the link quality,several nodes are selected to jam illegal nodes.Both simulation and field experiment show that the proposed scheme can accurately find the illegal nodes in the time-vary channel and improve the security of the network.

RSS Based Bridge Scour Measurement Using Underwater Acoustic Sensor Networks

Bridge Scour is one of the major causes of bridge failures all around the world and there have been significant efforts for its detection and measurement using different acoustic approaches. In this paper, we propose and investigate an effective method to utilize Received Signal Strength (RSS) for measuring scour depth where acoustic sensors are deployed. We also extend a statistical testing to determine the difference in signal levels at the sensor nodes prior to and after scour formation and subsequently determine the actual depth of scour. Additionally, we make an attempt to evaluate underwater distance and depth using signal strength perceived at the receiver which makes it free from the requirement of accurate receiver-sender synchronization in contrast to Time of Flight (ToF) or Time of Arrival (ToA) techniques. The scour depths are eventually compared for the conditions when the bottom is composed of a single or multiple layers. The simulation results clearly show that different depths are calculated for the case of multilayered bottom (0.8 to 3.9 meters for instance) as compared to a constant depth of 2 meters for the case of a single layered bottom.

Provisioning Intelligent Water Wave Optimization Approach for Underwater Acoustic Wireless Sensor Networks

In the Acoustics channel,it is incredibly challenging to offer data transfer for time-sourced applications in an energy-efficient manner due to higher error rate and propagation delay.Subsequently,conventional re-transmission over any failure generally initiates significantly larger end-to-end delay,and therefore it is not probable for time-based services.Moreover,standard techniques without any re-transmission consume enormous energy.This investigation proposes a novel multi-hop energy-aware transmission-based intelligent water wave optimization strategy.It ensures reduced end-to-end while attaining potential amongst overall energy efficiency end-to-end packet delay.It merges a naturally inspired meta-heuristic approach with multi-hop routing for data packets to reach the destination.The appropriate design of this Meta heuristic-based energy-aware scheme consumes lesser energy than the conventional one-hop transmission strategy without re-transmission.However,there is no hop-by-hop re-transmission facilitated.The proposed model shows only lesser delay than conventional methods with re-transmission.This work facilitates extensive work to carry out the proposed model performance with the MATLAB simulation environment.The results illustrate that the model is exceptionally energyefficient with lesser packet delays.With 500 nodes,the packet delivery ratio of proposed model is 100%,average delay is reduced by 2%,total energy consumption is 8 J,average packet redundancy is 1.856,and idle energy is 6.9Mwh.The proposed model outperforms existing approaches like OSF,AOR,and DMR respectively.

A Survey of Ranging Algorithms and Localization Schemes in Underwater Acoustic Sensor Network

Underwater Acoustic Sensor Network(UASN) has attracted significant attention because of its great influence on ocean exploration and monitoring. On account of the unique characteristics of underwater environment, localization, as one of the fundamental tasks in UASNs, is a more challenging work than in terrestrial sensor networks. A survey of the ranging algorithms and the network architectures varied with different applications in UASNs is provided in this paper. Algorithms used to estimate the coordinates of the UASNs nodes are classified into two categories: rangebased and range-free. In addition, we analyze the architectures of UASNs based on different applications, and compare their performances from the aspects of communication cost, accuracy, coverage and so on. Open research issues which would affect the accuracy of localization are also discussed, including MAC protocols, sound speed and time synchronization.

Spectrum Allocation and Protocol Based on Cognitive Acoustic Technique in Underwater Networks

In this paper, a strategy is developed for spectrum sharing among multiple cognitive users in underwater environment. This strategy requires all nodes to negotiate and reallocate the channels before sending data, and Hungarian method is used to maximize the sharing rewards. Simulation results show that the proposed strategy can avoid collisions between source-destination node pairs, and guarantee that the communication system gets maximum sharing rewards. Both the parameters of POMDP model and the number of available channels have influence on the system sharing rewards, and the rewards will increase when the channels have larger transition probabilities or more channels are available for communication. However, the channels with larger bandwidths can attract more nodes to access, and thus will lead to more collisions.

Energy-Efficient Mobile Data Collection Adopting Node Cooperation in an Underwater Acoustic Sensor Network

This paper considers an underwater acoustic sensor network with one mobile surface node to collect data from multiple underwater nodes,where the mobile destination requests retransmission from each underwater node individually employing traditional automatic-repeat-request(ARQ) protocol.We propose a practical node cooperation(NC) protocol to enhance the collection efficiency,utilizing the fact that underwater nodes can overhear the transmission of others.To reduce the source level of underwater nodes,the underwater data collection area is divided into several sub-zones,and in each sub-zone,the mobile surface node adopting the NC protocol could switch adaptively between selective relay cooperation(SRC) and dynamic network coded cooperation(DNC) .The difference of SRC and DNC lies in whether or not the selected relay node combines the local data and the data overheard from undecoded node(s) to form network coded packets in the retransmission phase.The NC protocol could also be applied across the sub-zones due to the wiretap property.In addition,we investigate the effects of different mobile collection paths,collection area division and cooperative zone design for energy saving.The numerical results showthat the proposed NC protocol can effectively save energy compared with the traditional ARQ scheme.

A zeroing neurodynamics‐based location method for nodes in underwater acoustic sensor network

Zeroing neurodynamics methodology,which dedicates to finding equilibrium points of equations,has been proven to be a powerful tool in the online solving of problems with considerable complexity.In this paper,a method for underwater acoustic sensor network(UASN)localisation is proposed based on zeroing neurodynamics methodology to preferably locate moving underwater nodes.A zeroing neurodynamics model specifically designed for UASN localisation is constructed with rigorous theoretical analyses of its effectiveness.The proposed zeroing neurodynamics model is compatible with some localisation algorithms,which can be utilised to eliminate error in non‐ideal situations,thus further improving its effectiveness.Finally,the effectiveness and compatibility of the proposed zeroing neurodynamics model are substantiated by examples and computer simulations.

Lifetime Prolonging Algorithms for Underwater Sensor Networks

Underwater acoustic modem technology has attained a level of maturity to support underwater acoustic sensor networks （UASNs） which are generally formed by acoustically connected sensor nodes and a surface station providing a link to an on-shore control center. While many applications require long-term monitoring of the deployment area, the batterypowered network nodes limit the lifetime of UASNs. Therefore, designing a UASN that minimizes the power consumption while maximizing lifetime becomes a very difficult task. In this paper, a method is proposed to determine the optimum number of clnstens throngh combining an application-specific protocol architecture and underwater acoustic communication model so as to reduce the energy dissipation of UASNs. Deploying more sensor nodes which work alternately is another way to prolong the lifetime of UASNs, An algorithm is presented for selecting sensor nodes and putting them into operation in each round, ensuring the monitoring to the whole given area. The present results show that the algorithm can help prolong system lifetime remarkably when it is applied to other conventional approaches for sensor networks under the condition that the sensor node density is high.

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.

水声传感器网络仿真框架UASNSF的设计

仿真是目前水声传感器网络的主要研究手段,在总结现有水声通信网络仿真工作的基础上,提出了水声传感器网络仿真框架UASNSF,并对其体系结构、组成模型、应用场景等几方面进行了描述,最后通过一个典型的水声传感器网络仿真应用,对该框架的实用性进行了验证。仿真结果证明,该仿真框架兼顾了模型准确性和仿真效率,可以方便地实现对水声传感器网络系统的全面模拟,为水声传感器网络的研究与设计提供了较好的实验平台。

Funneling media access control (MAC) protocol for underwater acoustic sensor networks

Due to the characteristics of the underwater acoustic channel, such as long propagation delay and low available bandwidth, the media access control (MAC) protocol designed for underwater acoustic sensor networks (UWASNs) is quite different from that for terrestrial wireless sensor networks. In this paper, we propose a MAC protocol for the UWASNs, named the funneling MAC (FMAC-U), which is a contention-based MAC protocol with a three-way handshake. The FMAC-U protocol uses an improved three-way handshake mechanism and code division multiple access (CDMA) based technology for request-to-send (RTS) signals transmitting to the sink in order that the sink can receive packets from multiple neighbors in a fixed order during each round of handshakes. The mechanism reduces the packet collisions and alleviates the funneling effect, especially alleviating the choke point of the UWASNs. Simulation results show that the proposed FMAC-U protocol achieves higher throughput, smaller packet drop ratio, lower end-to-end delay, and lower overhead of the control packet compared to the existing MAC protocols for UWASNs.

A Dedicated MAC Protocol Package for Real-Time Ocean Current Field Estimation Using Distributed Underwater Acoustic Sensor Networks

Distributed underwater acoustic sensor networks(UASNs)are envisioned in real-time ocean current velocity estimation.However,UASNs at present are still dominated by post-processing partially due to the complexity of on-line detection for travel times and lack of dedicated medium access control(MAC)protocols.In this study,we propose a dedicated MAC protocol package for real-time ocean current velocity estimation using distributed UASNs.First,we introduce the process and requirements of ocean current velocity estimation.Then,we present a series of spatial reuse time division multiple access(TDMA)protocols for each phase of real-time ocean current field estimation using distributed UASNs,followed by numerical analysis.We divide UASNs into two categories according to their computing ability:feature-complete and feature-incomplete systems.The feature-complete systems that have abundant computing ability carry out the presented MAC protocol package in three phases,whereas the feature-incomplete ones do not have enough computing ability and the presented MAC protocol package is reduced to two phases plus an additional downloading phase.Numerical analysis shows that feature-complete systems using mini-slot TDMA have the best real-time performance,in comparison with feature-incomplete systems and other feature-complete counterparts.Feature-incomplete systems are more energy-saving than feature-complete ones,owing to the absence of in-network data exchange.

A Cooperative Security Monitoring Mechanism Aided by Optimal Multiple Slave Cluster Heads for UASNs

As each cluster head(CH)sensor node is used to aggregate,fuse,and forward data from different sensor nodes in an underwater acoustic sensor network(UASN),guaranteeing the data security in a CH is very critical.In this paper,a cooperative security monitoring mechanism aided by multiple slave cluster heads(SCHs)is proposed to keep track of the data security of a CH.By designing a low complexity“equilateral triangle algorithm(ETA)”,the optimal SCHs(named as ETA-based multiple SCHs)are selected from the candidate SCHs so as to improve the dispersion and coverage of SCHs and achieve largescale data security monitoring.In addition,by analyzing the entire monitoring process,the close form expression of the probability of the failure attack identification for the SCHs with respect to the probability of attack launched by ordinary nodes is deduced.The simulation results show that the proposed optimal ETA-based multiple SCH cooperation scheme has lower probability of the failure attack identification than that of the existing schemes.In addition,the numerical simulation results are consistent with the theoretical analysis results,thus verifying the effectiveness of the proposed scheme.

An Acoustic Modem Featuring a Multi-Receiver and Ultra-Low Power

Wireless technology for underwater communication possesses a wide range of potential application, but it is still a relatively unexplored area in many aspects concerning modems physical design. A step towards future deployment of underwater networks is the reduction of power consumption. Therefore, asynchronous wakeup systems need to be integrated within the physical layer design while avoiding the use of additional transducers. This paper offers a practical and generic solution to adapt data reception and transmission together with asynchronous wakeup sub-systems in acoustic underwater modem architectures using a low power and low cost solution. The proposal has been implemented in a real prototype with success.

UASN中改进的锚点定位报文传输方案

水下声学传感器网络具有传输延时较长、数据速率较低、传输损耗较大等特点,影响着现有定位算法的报文传输效率。针对水下声学传感器网络中现有定位算法在报文传输效率方面的不足,提出了一种改进的定位报文传输方案。首先,已知锚点的相对位置及其最大传输范围后,分析了定位时的无冲突报文传输条件,然后定义定位任务时间最小化问题,并证明该问题可以获得最优解。在此基础上,提出两种基于调度的低复杂度求解算法。最后,通过多次仿真实验来比较该改进算法与OCSMA等当前水下MAC协议及传统的时隙方法的性能,实验结果表明本文算法的性能达到准最优水平,且远优于TDMA和OCSMA等其他当前算法。

UASN中改进的锚点定位报文传输方案研究

定位问题是水下声学传感器网络的一个关键问题,如果节点采集到的数据没有附上时间和测量位置便没有意义。针对现有定位算法在报文传输效率方面的不足,文中提出了一种改进的定位报文传输方案。首先,已知锚点的相对位置及其最大传输范围后,分析了定位时的无冲突报文传输条件,然后,定义了定位任务时间最小化问题,并证明该问题可以获得最优解。在此基础上,提出了两种基于调度的低复杂度求解算法。最后,通过多次仿真验证了所提出的算法的准最优性能及相对其他当前算法的优越性。