Secure Communication Techniques for Underwater WSNs

In the past few decades, optical communication with high data rates up to Gb/s in underwater wireless sensor networks (UWSN) has been extensively investigated. However, now a days researchers are highly focused on proposing/implementing localization algorithms for underwater optical wireless sensor networks (UOWSN) that are both fast in computation and cost efficient in terms of hardware design. In this paper we have used two different setups, one consisting of one led as a transmission node Tx. Where we exploit the effects of different angle on optical communication by implementing Lambert cosine law in a (UOWSN). The second setup is made of a led clutch which can communicate in 360 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> . Both setups are used to estimate the location of a sensor node Rx in (UOWSN). To complete the task of localization estimation, a multilateration algorithm based on Euclidean distance between the Tx and Rx nodes is used, where as Gauss–Newton method was used to find the minimum of the function.

Performance modeling and analysis of void-handling methodologies in underwater wireless sensor networks

Underwater wireless sensor networks nodes deployment optimization problem is studied and underwater wireless sensor nodes deployment determines its capability and lifetime. If no underwater wireless sensor node is available in the monitoring area of underwater wireless sensor networks due to used up energy or any other reasons, the monitoring area where is not detected by any underwater wireless sensor node forms coverage holes. In order to improve the coverage of the underwater wireless sensor networks and prolong the lifetime of the underwater wireless sensor networks, based on the perception model, establish nodes detection model, combining with the data fusion. Because the underwater wireless sensor networks nodes coverage holes appear when the initial randomly deployment, a nodes deployment algorithm based on perception model of underwater wireless sensor networks is designed in this article. The simulation results show that this algorithm can effectively reduce the number of deployment underwater wireless sensor networks nodes, improve the efficiency of underwater wireless sensor networks coverage, reduce the underwater wireless sensor networks nodes energy consumption, prolong the lifetime of the underwater wireless sensor networks.

Water covers more than 70 % of the entire planet, contains much of its natural resources. With the increasing use of underwater sensors for the exploitation and monitoring of vast underwater resources, underwater wireless sensor network (UWSN), mostly based on acoustic transmission technologies, have been developing steadily in terms of operation range and data throughput. In an energy-constrained underwater system environment it is very important to find ways to improve the life expectancy of the sensors. Compared to the sensors of a terrestrial Ad Hoc Wireless Sensor Network (WSN), underwater sensors cannot use solar energy to recharge the batteries, and it is difficult to replace the batteries in the sensors. This paper reviews the research progress made to date in the area of energy consumption in underwater sensor networks (UWSN) and concentrates on developing routing algorithms that support energy efficiency. These algorithms are designed to carry out data communication while prolonging the operation time of WSNs.

Underwater acoustic communication is a method of sending and receiving messages beneath the water&#x2019;s surface that has been extensively researched for long-distance communication and localization. While, in this paper we will focus on medium range optical communication localization and short range Magneto Inductive (MI) communication localization. Both optical wireless sensor networks (OWSNs) and magneto inductive wireless sensor networks (MIWSNs) are investigated for localization of sensor nodes using a received signal strength indicator (RSSI) based localization technique for underwater environment/medium. Location information for MI nodes is obtained directly from mutual coupling measurement with a proposed localization scheme. Where as the localization of optical sensor nodes is done by exploiting the Lambert cosine law which gives values for luminous intensity in different distances and orientations. A simulation environment for both underwater optical wireless sensor networks (UOWSNs), and underwater magneto inductive wireless sensor networks (UMIWSNs) consisting of eight Tx anchor nodes and ten Rx sensor nodes is created to elaborate the localization estimation results.

Wireless sensor networks (WSNs) are network of physical small sensors which are interconnected through wireless links. WSNs are ubiquitous in diverse types of environment such as air interface and underwater acoustic communication. WSNs are responsible for collecting data, accomplishing appropriate operations on it and if required then relay it to the sink node. WSNs had many issues and challenges specifically in underwater wireless sensor network (UWSN). Secondly there is an issue of network life time as the sensor nodes have limited battery and it is challenging to replace it frequently specially in UWSN. An important challenge in the performance of the DBR is the energy constraint due to limited battery life time, which can cause the entire network to go down. In this paper, we propose an Energy Harvesting Depth Based Routing Protocol (EH-DBR) protocol. Our proposed protocol (EH-DBR) sensor node harvest and store power via external acoustic source in the form of packets. The key advantage of our protocol is that its lifetime will be extended indefinitely. Moreover, our routing protocol can take advantage of DBR architecture without introducing extra cost. We conduct extensive simulations. The results show that EH-DBR can achieve very high packet delivery ratios due to long time performance.

The underwater wireless sensor network (UWSN) is considered a promising technology for collecting valuable data from underwater areas, particularly for aiding military operations and environmental predictions. UWSNs consist of underwater sensor nodes that have limited energy and use acoustics for communication. Routing in underwater sensor nodes is one of the challenging issues in UWSNs because of the need to forward data packets with minimal energy consumption and a high packet delivery ratio. Selecting the next forwarding nodes is one of the key components of routing in UWSNs and has a direct effect on energy consumption and the packet delivery ratio. Therefore, this problem has gained much attention from the research community with the intent of enhancing the performance of UWSNs. This paper qualitatively reviews routing protocols for UWSNs, focusing on the next-hop selection method and its strengths and weaknesses. A taxonomy is presented for reviewing routing protocols under different categories of the classification. A summary of the qualitative investigation is presented highlighting aims, the next-hop selection method, metrics, and priority considerations. A comprehensive investigation is carried out focusing on energy, link quality, void awareness, reliability, and shortest path characteristics. Finally, we discuss potential future research directions in UWSNs for forwarding node selection.

Underwater wireless sensor networks (UWSNs) are a subclass of wireless sensor networks. Underwater sensor deployment is a significant challenge due to the characteristics of UWSNs and underwater environment. Recent researches for UWSNs deployment mostly focus on the maintenance of network connectivity and maximum communication coverage. However, the broadcast nature of the transmission medium incurs various types of security attacks. This paper studies the security issues and threats of UWSNs topology. Based on the cluster-based topology, an underwater cluster-based security scheme (U-CBSS) is presented to defend against these attacks. and safety.

Owing to the rapid development of underwater applications, the research on underwater wireless sensor networks (UWSNs) is becoming more and more significant. Low bandwidth, high latency, limited energy and node float mobility are basic challenges for underwater sensor networks. Most of the theories for terrestrial sensor networks can not be applied to underwater sensor networks. In this paper, we focus on the localization and routing issues for dynamic UWSNs. Location based routing protocols can suit the dynamic situation of UWSNs well. However, most research assumes that the nodes know their locations, which may be not appropriate for some applications. This paper combines these two aspects together to design a localization based routing protocol for dynamic UWSNs. The simulation results show our method can effectively route data from the source nodes to the sink nodes in a dynamic environment.

Packet collision in underwater wireless sensor networks (UWSNs) can create inconsistent time stamps leading to inaccurate time synchronization in underwater sensor networks. Most extant time synchronization techniques do not model for the probability of packet collision in UWSNs. This paper proposes a novel non-homogenous Poisson process (NHPP)-based back-off technique that estimates probability of packet collision in UWSN over a set period of time and allows sending of data packets only when probability of collision in a network is low. Any inconsistent time stamps are further identified and removed using Mahalanobis distance technique before linear regression is run. The proposed method performs better in extensive simulations as compared to two similar time synchronization techniques in literature.KeywordsUWSNsNon-homogenous Poisson processPacket collisionTime synchronization

Recently, underwater wireless sensor network (UWSN) has paved the way for researchers towards a new era of exploring ocean realm targeting envisioned landscape of underwater applications. These applications can be made viable through underwater communication by using acoustic waves, giving rise to several design challenges like limited bandwidth, large and variable propagation delay, frequent connectivity loss, etc. Reliable data delivery in UWSN is always a tempting issue to be addressed, which is jeopardised by link failures and communication void. Under this context, Link failure Avoidance and Void Recovery (LAVR) routing protocol is proposed that uses link quality as forwarding factor, computed using Triangle Metric, to achieve reliability. A void node recovery procedure is proposed to displace the void node to a new depth to increase the packet delivery ratio. Simulations are performed in Aqua-Sim simulator and LAVR outperforms other existing protocols in terms of packet delivery ratio and network lifetime.

Underwater wireless sensor network nodes deployment optimization problem is studied and underwater wireless sensor nodes deployment determines its capability and lifetime. Underwater wireless sensor network if no wireless sensor node is available in the area due to used up energy or any other reasons, the area which is not detected by any wireless sensor node forms coverage holes. The coverage holes recovery algorithm aiming at the coverage holes in wireless sensor network is designed in this article. The nodes movement is divided into several processes, in each movement process according to the balance distance and location relations move nodes to separate the aggregate nodes and achieve the maximum coverage of the monitoring area. Because of gradually increasing the balance distance between nodes, in each movement process the nodes movement distance is small and reduce the sum of the nodes movement distance. The simulation results show that this recovery algorithm achieves the goal of the nodes reasonable distribution with improving the network coverage and reducing the nodes movement distance thus extends the lifetime of the underwater wireless sensor network in the initial deployment phase and coverage holes recovery phase.

Underwater Wireless Sensor Network (UWSN) is a newly emerging wireless technology in which small size sensors with limited energy and limited memory and bandwidth are deployed in deep sea water and various monitoring operations like tactical surveillance, environmental monitoring, and data collection are performed through these tiny sensors. Underwater wireless sensor networks are used for the exploration of underwater resources, oceanographic data collection, flood or disaster prevention, tactical surveillance systems, and unmanned underwater vehicles. Sensor nodes consist of a small memory, a central processing unit, and an antenna. Underwater networks are much different from terrestrial sensor networks as radio waves cannot be used in underwater wireless sensor networks. Acoustic channels are used for communication in deep sea water. Acoustic signals have many limitations, such as limited bandwidth, higher end-to-end delay, network path loss, higher propagation delay, and dynamic topology. Usually, these limitations result in higher energy consumption with a smaller number of packets delivered. The main aim nowadays is to operate sensor nodes having a smaller battery for a longer time in the network. This survey has discussed the state-of-the-art localization based and localization-free routing protocols. Routing associated issues in area of underwater wireless sensor networks have also been discussed.

Underwater wireless optical sensor networks require high-speed, long-range, and scalable underwater wireless optical communication/ultra-wideband hybrid links to enable real-time data transmission and reliable communication between sensors and surface stations. Such hybrid links can provide seamless connectivity, adaptability to changing underwater environments, and support for various applications including ocean exploration, monitoring, and surveillance. We report an underwater wireless optical communication/ultra-wideband converged transmission link for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:mrow><mml:mn>5</mml:mn><mml:mo>×</mml:mo><mml:mn>1.5</mml:mn></mml:mrow></mml:math> Gb/s underwater wireless optical sensor networks. The directly-modulated lasers are used to modulate and transmit the sensors’ data over underwater wireless optical communication channels towards floating optical base station having radio-access units where multiple ultra-wideband signals are generated employing optical delay line technique. Intensity modulation/direct detection scheme based upon On-off keying modulation is employed in this work. The performance of the sensors is examined taking into account various water bodies and turbulence regimes using metrics of Bit-error rate, Quality factor, and Error-vector magnitude utilizing Gamma-Gamma statistical channel model. The simulation results obtained indicate that forward-error correction target Bit-error rate of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m2"><mml:mrow><mml:mn>3.8</mml:mn><mml:mo>×</mml:mo><mml:mn>1</mml:mn><mml:msup><mml:mrow><mml:mn>0</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>3</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math> is successfully achieved for sensors considering different water bodies and turbulence regimes. The proposed system is potentially scalable, accommodating increased sensors, and supporting higher rates while efficiently generating and processing ultra-wideband signals.

In underwater wireless sensor network communication, communication performance degrades due to factors such as complex underwater channels and limited node resources. To reduce node redundancy energy consumption, improve transmission reliability, and extend the overall network lifetime, this study proposes an intelligent network performance optimization algorithm based on multi-agent reinforcement learning. By constructing an underwater wireless sensor network system model including fixed and mobile nodes, the network performance optimization problem is formalized as a partially observable Markov decision process. Then, multi-agent reinforcement learning is used to construct a comprehensive team reward function containing fair reuse rewards and survival time penalties, thereby establishing a distributed intelligent power management scheme. This solution enables each node to make transmission power decisions based on local observations, combined with the underlying media access control protocol, to collaboratively optimize higher-layer network performance indicators. The results show that in heterogeneous network scenarios, the proposed method achieves a network capacity of 245.68 kb and a fairness reuse index of 1.85. In imperfect networks with 5% node failures, the average communication latency is only 6.18 time slots, which is superior to the comparative algorithm. Under dynamic environments with a signal-to-interference-plus-noise ratio of 10-16 dB and a water flow velocity of 2.0 m/s, it can still maintain a network capacity of over 32,045 kb and an energy efficiency of 0.4 kb/J. These findings demonstrate that the proposed method significantly improves the robustness of underwater wireless sensor networks, providing communication support for ocean monitoring.