Routing Protocols for Underwater Acoustic Sensor Networks: A Survey from an Application Perspective

Underwater acoustic communications are different from terrestrial radio communications; acoustic channel is asymmetric and has large and variable end‐to‐end propagation delays, distance‐dependent limited bandwidth, high bit error rates, and multi‐path fading. Besides, nodes’ mobility and limited battery power also cause problems for networking protocol design. Among them, routing in underwater acoustic networks is a challenging task, and many protocols have been proposed. In this chapter, we first classify the routing protocols according to application scenarios, which are classified according to the number of sinks that an underwater acoustic sensor network (UASN) may use, namely single‐sink, multi‐sink, and no‐sink. We review some typical routing strategies proposed for these application scenarios, such as cross‐layer and reinforcement learning as well as opportunistic routing. Finally, some remaining key issues are highlighted

DOW-PR dolphin and whale pods routing protocol for underwater wireless sensor networks (UWSNs)

Underwater Wireless Sensor Networks (UWSNs) have intrinsic challenges that include long propagation delays, high mobility of sensor nodes due to water currents, Doppler spread, delay variance, multipath, attenuation and geometric spreading. The existing Weighting Depth and Forwarding Area Division Depth Based Routing (WDFAD-DBR) protocol considers the weighting depth of the two hops in order to select the next Potential Forwarding Node (PFN). To improve the performance of WDFAD-DBR, we propose DOlphin and Whale Pod Routing protocol (DOW-PR). In this scheme, we divide the transmission range into a number of transmission power levels and at the same time select the next PFNs from forwarding and suppressed zones. In contrast to WDFAD-DBR, our scheme not only considers the packet upward advancement, but also takes into account the number of suppressed nodes and number of PFNs at the first and second hops. Consequently, reasonable energy reduction is observed while receiving and transmitting packets. Moreover, our scheme also considers the hops count of the PFNs from the sink. In the absence of PFNs, the proposed scheme will select the node from the suppressed region for broadcasting and thus ensures minimum loss of data. Besides this, we also propose another routing scheme (whale pod) in which multiple sinks are placed at water surface, but one sink is embedded inside the water and is physically connected with the surface sink through high bandwidth connection. Simulation results show that the proposed scheme has high Packet Delivery Ratio (PDR), low energy tax, reduced Accumulated Propagation Distance (APD) and increased the network lifetime

Efficient ARQ algorithm based on majority logic decision

Primena diverziti tehnike i majoritetnog kombinovanja paketa predstavlja jednostavno i atraktivno rešenje za kontrolu grešaka u bežičnim telekomunikacionim sistemima. Ove tehnike su posebno interesantne u paketski orijentisanim mrežama sa višestrukim putanjama i kooperativnim mrežama sa jednom ili više predajnih i prijemnih antena. Tipičan primer su bežične senzorske mreže koje često rade u ekstremno otežanim uslovima prenosa, pri čemu zahtevi za pouzdanim prenosom imaju veći prioritet od zahteva za racionalnim korišćenjem komunikacionih kapaciteta. Teorijski i aproksimativni izrazi za verovatnoću pogrešnog prenosa paketa u slučaju proizvoljnog broja kanala sa različitim verovatnoćama grešaka predstavljaju ključne parametre za procenu energetske efikasnosti senzorskih čvorova. Cilj rada: U okviru ove problematike, u tezi su postavljeni sledeći ciljevi: (i) da se dobiju teorijski izrazi za verovatnoću pogrešnog prenosa paketa u slučaju primene selektivnog i majoritetnog odlučivanja, u uslovima kada su verovatnoće grešaka različite na različitim putanjama i kada je broj mogućih paralelnih putanja proizvoljan; analitički izrazi su veoma bitni prilikom odreĎivanja optimalnog broja putanja u senzorskoj mreži sa ciljem maksimalne uštede potrošnje energije u senzorskim čvorovima, (ii) da se analizira efikasnost hibridne ARQ šeme imajući u vidu različita scenarija pristizanja paketa u odredišni čvor; naime, prisustvo prostornih putanja pri kojima su na pojedim putanjama uslovi prenosa loši, ne obezbeĎuje garantovano prepoznavanje paketa i prenos po svim putanjama, tako da se uslovi za majoritetno odlučivanje mogu obezbediti posle jedne ili više retransmisija; zbog toga, realni scenario je kombinacija prostornog i vremenskog diverzitija u korist jednog ili drugog scenarija, (iii) da se sagleda mogućnost implementacije imajući u vidu korišćenje poznatih standarda i postojećih hardverskih i softverskih rešenja koja se koriste u senzorskim mrežama; posebno težište je bilo dato modifikaciji rešenja neohodnih za implementaciju korekcije grešaka na bazi majoritetnog kombinovanja paketa...The application of diversity technique and majority packet combining is a simple and attractive solution for error control in wireless telecommunication systems. These techniques are especially interesting in packet-oriented multipath and cooperative networks with one or more transmitting and receiving antennas. A typical example is wireless sensor network which often operates in extremely harsh conditions, where requirements for reliable packet transmission have a higher priority than requirements for efficient usage of communication capacities. Theoretical and approximate expressions of packet error probabilities in the case of an arbitrary number of channels with distinct channel error probabilities are key parameters for estimation of the energy efficiency of sensor nodes. Goal of research: As part of this problem, the thesis sets the following objectives: (i) to obtain theoretical expressions for packet error probability in the case of application of selective and majority decision when the number of parallel channels is arbitrary and channel error probabilities are distinct; analitical expressions are very important in determining the optimal number of paths in a sensor network in order to achieve maximum saving of energy in sensor nodes, (ii) to analyze the throughput efficiency of a hybrid ARQ scheme, considering various scenarios of packet receiving in the destination node; namely, the presence of spatial paths, with poor transmission conditions in certain paths, does not provide guaranteed detection and transmission of frame copies via all paths, so that the conditions for majority combining may be provided after one or more retransmissions; therefore, the real scenario is a combination of space and time diversity in favor of one or the other scenario, (iii) to examine the possibility of implementation of majority combining, having in mind the known standards and the usage of existing hardware and software solutions in sensor networks; the particular focus was given to the modification of solutions required for the implementation of error correction, based on majority packet combining..

EFFICIENT DYNAMIC ADDRESSING BASED ROUTING FOR UNDERWATER WIRELESS SENSOR NETWORKS

This thesis presents a study about the problem of data gathering in the inhospitable underwater environment. Besides long propagation delays and high error probability, continuous node movement also makes it difficult to manage the routing information during the process of data forwarding. In order to overcome the problem of large propagation delays and unreliable link quality, many algorithms have been proposed and some of them provide good solutions for these issues, yet continuous node movements still need attention. Considering the node mobility as a challenging task, a distributed routing scheme called Hop-by-Hop Dynamic Addressing Based (H2- DAB) routing protocol is proposed where every node in the network will be assigned a routable address quickly and efficiently without any explicit configuration or any dimensional location information. According to our best knowledge, H2-DAB is first addressing based routing approach for underwater wireless sensor networks (UWSNs) and not only has it helped to choose the routing path faster but also efficiently enables a recovery procedure in case of smooth forwarding failure. The proposed scheme provides an option where nodes is able to communicate without any centralized infrastructure, and a mechanism furthermore is available where nodes can come and leave the network without having any serious effect on the rest of the network. Moreover, another serious issue in UWSNs is that acoustic links are subject to high transmission power with high channel impairments that result in higher error rates and temporary path losses, which accordingly restrict the efficiency of these networks. The limited resources have made it difficult to design a protocol which is capable of maximizing the reliability of these networks. For this purpose, a Two-Hop Acknowledgement (2H-ACK) reliability model where two copies of the same data packet are maintained in the network without extra burden on the available resources is proposed. Simulation results show that H2-DAB can easily manage during the quick routing changes where node movements are very frequent yet it requires little or no overhead to efficiently complete its tasks

High Power Capacitive Power Transfer for Electric Vehicle Charging Applications

Capacitive power transfer (CPT) technology is an effective way to charge electric vehicles, in which electric fields between metal plates are used to transfer power. Compared to the conventional inductive power transfer (IPT) system, a CPT system has three advantages: it does not generate eddy-current loss in nearby metal objects; it can reduce the system weight and cost; it has better misalignment performance. However, the coupling capacitance in a CPT system is usually in the pF range, which limits the CPT system power and efficiency. Through overcoming the limitation of small capacitance in a CPT system, this dissertation has achieved three breakthroughs in CPT technology: the system power is increased from several tens of watts to several kW; the transfer distance is increased from less than 1 mm to hundreds of mm; the transfer efficiency is increased from about 30% to over 90%. A double-sided LCLC compensation circuit has been proposed to realize high-power and long-distance capacitive power transfer. The compensation circuit provides resonances with the coupling capacitance, and increases the voltages on metal plates to kV level to achieve kW power transfer. A prototype has been constructed and validates the proposed circuit. Experimental results show that the prototype realizes 2.4 kW power transfer across an air-gap distance of 150 mm with a dc-dc efficiency of 90.8%. The experiments also show that the CPT system has better misalignment performance than the conventional IPT system. An IPT-CPT combined system has also been proposed to integrate the IPT and CPT technology together. The combination can increase the efficiency of the CPT system, and improve the misalignment performance of the IPT system. A prototype has been constructed to validate the combined idea. Experimental results show that the prototype realizes 2.84 kW power transfer across an air-gap distance of 150 mm with a dc-dc efficiency of 94.4%. Using the designed LCLC compensation circuit, a dynamic CPT system has been proposed to realize power transfer to receivers in moving status. A long-track coupler structure is used to reduce the pulsation of received power. A prototype has been constructed to validate dynamic charging. Experimental results show that the prototype realizes 154W power transfer across an air-gap distance of 50 mm with a dc-dc efficiency of 85.4%. Considering practical applications, the safety issues and foreign object influence have been studied in this dissertation. The high voltage issue can be solved by reliable insulation, and the electric field emissions can be reduced through capacitive coupler structure design. The foreign object, either metallic or dielectric, can influence the coupling capacitances in a CPT system depends on the position and size. The CPT system can also influence the voltage and power loss in the foreign object. To sum up, this dissertation has demonstrated that the CPT technology is a good solution to realize the charging of electric vehicles. In future work, the power density and efficiency of the CPT system will be further improved to make it more competitive with the inductive and conductive charging technology.PHDElectrical Engineering: SystemsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/138493/1/feilu_1.pd