attention due to their important underwater applications for military and commercial purposes. Underwater wireless communication networks (UWCNs) consist of. Abstract—Underwater wireless communications can be carried out through the jitter of transceivers were studied in  where PDF of. Underwater Wireless Sensor Networks and Nodes. soundofheaven.info soundofheaven.info), in any relevant.
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UNDERWATER WIRELESS COMMUNICATION NETWORK CHAPTER 1 INTRODUCTION Earth is largely covered by water. This is largely unexplored area and. Underwater Wireless Communication Seminar and PPT with pdf report: Underwater wireless communication is a prosperous research area in. PDF | The system uses the ultra-low power MSPF MCU as the control core, and uses the infrared wireless communication, achieving a.
Submit Search. No notes for slide. The state of the art in current underwater networking technology is oriented towards a setup as shown in Figure 3. This communication will happening between underwater sinker cluster head to sensors. This means that large amounts of data are sent as a series of these data packages. One classification discriminates between static, semi mobile and mobile architectures.
They are usually smaller in size, battery operated, and they mostly transmit data via acoustic modems. The cluster heads are also anchored to the ocean floor. In addition to having acoustic modems. Cluster heads are equipped with two acoustic transceivers, namely a vertical and a horizontal transceiver.
The horizontal transceiver is used by the cluster head or uw- sink to communicate with the sensor nodes in order to send commands and configuration data to the sensors.
This communication will happening between underwater sinker cluster head to sensors. Collect monitored data. This communication will happening between sensors to cluster head or sink. Cluster heads communicate via horizontal acoustic modes with all other individual nodes within the cluster. The data transfer from node to cluster head can be single-hop each node communicated to the cluster head directly or multi-hop.
In case of multi-hop paths, as in terrestrial sensor networks, the data produced by a source sensor is relayed by intermediate sensors until it reaches the uw-sink. This results in energy savings and increased network capacity but increases the complexity of the routing functionality as well. The vertical trans receiver is used by the uw-sinks to relay data to a surface station. Vertical transceivers must be long range transceivers for deep water applications as the ocean can be as deep as 10 km.
The surface station is equipped with an acoustic transceiver that is able to handle multiple parallel communications with the deployed uw-sinks. Finally base or surface station will send the sensed data to on-shore base station via RF signal. Also, the cluster head is potentially the most security-vulnerable component in UWSNs military applications, because it is a single point of failure node.
Three dimensional underwater networks are used to detect and observe phenomena that cannot be adequately observed by means of ocean bottom sensor node, i. In 3D architecture, sensor node float at different depth in order to observe the given phenomenon.
In this architecture each sensor is anchored to the ocean bottom and equipped with a floating buoy that can inflated by a pump. The buoy pushes the sensor towards the ocean surface.
The depth of sensor then can be regulated by adjusting the length of wire that connect the sensor to the anchor, by means of an electronically controlled engine that reside on sensor.
In the former case, all nodes are of the same type, but communication might be more energy intensive than that of the cluster head approach. The cluster head approach requires only the cluster head to carry a long-range communication modem. On the other hand, the clustered approach is vulnerable to single point of failure. Military applications are extremely sensitive to single point of failure hardware components.
Fig 4. Thus, network devices should coordinate their depths such a way that the network topology always connected, i.
The main important factor in this architecture is a mobility of nodes. Mobile node put extra controlling complexity in the network. In addition the network consume more power because they consume extra power due to force or movement of mobile node in water.
Moreover the mobile node is less reliable and shorter lifetime. Both mobile and static architecture has some advantages and disadvantages. In hybrid architecture that include uses both mobile node and static node by which we can transmit our sensed data efficiently from floor sensor to surface station. In this this architecture the mobile node traversing over the static field or static sensor and achieve the point-to-point communication.
Radio waves do not propagate well underwater due to the high energy absorption of water. Therefore, underwater communications are based on acoustic links characterized by large propagation delays. Acoustic channels have low bandwidth.
The link quality in underwater communication is severely affected by multipath, fading, and the refractive properties of the sound channel. As a result, the bit error rates of acoustic links are often high, and losses of connectivity arise.
Underwater sensors move with water currents, and AUVs are mobile. Although certain nodes in underwater applications are anchored to the bottom of the ocean, other applications require sensors to be suspended at certain depths or to move freely in the underwater medium.
The future development of geographical routing is very promising in UWCNs due to its scalability and limited signaling properties. Underwater communication systems have more stringent power requirements than terrestrial systems because acoustic communications are more power hungry, and typical transmission distances in UWCNs are greater; hence, higher transmit power is required to ensure coverage.
The above mentioned characteristics of UWCNs have several security implications. UWCNs suffer from the following vulnerabilities. High bit error rates cause packet errors. Consequently, critical security packets can be lost. Wireless underwater channels can be eavesdropped on.
Attackers may intercept the information transmitted and attempt to modify or drop packets. Malicious nodes can create out-of band connections via fast radio above the water surface and wired links, which are referred to as wormholes. Since sensors are mobile, their relative distances vary with time.
The dynamic topology of the underwater sensor network not only facilitates the creation of wormholes but it also complicates their detection. A jamming attack consists of interfering with the physical channel by putting up carriers on the frequencies neighbor nodes use to communicate.
Since underwater acoustic frequency bands are narrow, UWCNs are vulnerable to narrowband jamming. Localization is affected by the replay attack when the attacker jams the communication between a sender and a receiver, and later replays the same message with stale information posing as the sender.
Spread spectrum is the most common defence against jamming. Frequency hopping spread spectrum FHSS and direct sequence spread spectrum DSSS in underwater communications are drawing attention for their good performance under noise and multipath interference.
These schemes are resistant to interference from attackers, although not infallible. An attacker can jam a wide band of the spectrum or follow the precise hopping sequence when an FHSS scheme is used.
A high-power wideband jamming signal can be used to attack a DSSS scheme. Underwater sensors under a jamming attack should try to preserve their power. When jamming is continuous, sensors can switch to sleep mode and wake up periodically to check if the attack is over. When jamming is intermittent, sensors can buffer data packets and only send high-power high priority messages to report the attack when a gap in jamming occurs.
In ground- based sensor networks, other sensors located along the edge of the area under normal background noise and report intrusion to outside nodes.
That will cause any further traffic to be rerouted around the jammed region. However, this solution cannot be applied to UWCNs, since nodes underwater are usually sparsely deployed, which means there would not be enough sensors to delimit the jammed region accurately and reroute traffic around it.
Another solution proposed for ground-based sensor networks against jamming is to use alternative technologies for communication such as infrared or optical. However, this solution cannot be applied either, since optical and infrared waves are severely attenuated under water.
A wormhole is an out-of-band connection created by the adversary between two physical locations in a network with lower delay and higher bandwidth than ordinary connections. This connection uses fast radio above the sea surface or wired links to significantly decrease the propagation delay. In a wormhole attack the malicious node transfers some selected packets received at one end of the wormhole to the other end using the out-of-band connection, and re- injects them into the network.
This attack is devastating. Routing protocols choose routes that contain wormhole links because they appear to be shorter; thus, the adversary can monitor network traffic and delay or drop packets sent through the wormhole.
Localization protocols can also be affected by these attacks when malicious nodes claim wrong locations and mislead other nodes. Fig 5. However, accurate distance estimation depends on precise localization geographical packet leashes, wormhole detection using position information of anchors , tight clock synchronization temporal packet leashes , or use of specific hardware directional antennas.
In underwater communications accurate localization and time synchronization are still challenging. Since a wormhole contracts the virtual layout at certain regions, some nodes far away appear to be neighbors, and these contradictions can be detected visualizing the virtual layout.
A wormhole indicator variable is defined to compute the distortion in angles; the distortion in edge lengths is computed as the difference between the measured distances among neighboring sensors and the lengths of the reconstructed connections. In a sinkhole attack, a malicious node attempts to attract traffic from a particular area toward it; for example, the malicious node can announce a high-quality route.
Geographic routing and authentication of nodes exchanging routing information are possible defences against this attack, but geographic routing is still an open research topic in UWCNs. A node receiving a HELLO packet from a malicious node may interpret that the adversary is a neighbor this assumption is false if the adversary uses high power for transmission. Bidirectional link verification can help protect against this attack, although it is not accurate due to node mobility and the high propagation delays of UWCNs.
Authentication is also a possible defence.
Shadow zones are formed when the acoustic rays are bent and sound waves cannot penetrate. The acoustic channels have the following characteristics: When a signal is propagated through acoustic channel then it is received by the receiver through a direct path or surface reflection or bottom reflection and this happens due to ray bending of the acoustic waves.
The acoustic modem applied science offers two types of modulation and they are as follows: With the development in the acoustic modem applied science, sensor applied science and vehicular applied science the ocean engineering is moving towards integration of these tools into autonomous networks. As per the applications, the underwater network topologies are two types and they are as follows: Applications of the Underwater Wireless Communication: The applications of the underwater wireless communication are as follows: Advantages of Underwater Wireless Communication: The advantages of the underwater wireless communication are as follows: Disadvantages of Underwater Wireless Communication: The disadvantages of the underwater wireless communication are as follows: Content of the Seminar and pdf report for Underwater Wireless Communication.
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