Conference Paper

Energy Hole Minimization Technique for Energy Efficient Routing in Under Water Sensor Networks

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Energy conservation is one of the challenging tasks in Wireless Sensor Networks (WSNs) whether deployed on ground or underwater. Applications of Underwater Sensor Networks (UWSNs) are gradually increasing due to the remote nature of control and automatic data transmission to onshore base stations. However, this automatic mechanism of WSNs is totally based on their built-in battery, which can not be replaced during network operation. Depth based routing is a popular routing technique which, do not needs full dimensional location information. However, consideration of depth and residual energy information for selection of next hop are not enough for balanced energy consumption of WSNs. In this research work, we identified the areas where energy is consumed most in depth based routing techniques. Due to which energy hole may be created. In addition we introduced Receive Signal Strength Indicator (RSSI) based location identification and multilevel power transmission in depth based routing technique. Simulation result shows that the proposed technique gives better results than its counterparts.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Moreover, coverage repair process during network operation is not yet investigated in UWSNs. In this research work, which is extended form of our previous work in [13], we propose a coverage hole repair technique for UWSNs. Initially, we analyse depth based routing which enables us to identify the spots where most of the energy is consumed. ...
... Since radio waves are not practical in underwater environment, we have replaced these with acoustic waves. For location information, we use Received Signal Strength Indicator (RSSI) as location finder [13], and use MoteTrack location identification scheme [14]. We are also motivated to address the following challenges among the mentioned ones in Section I. ...
Article
Due to the limited battery capacity of sensor nodes, a minimization of energy consumption is a potential research area in underwater wireless sensor networks (UWSNs). However, energy hole and coverage hole creations lead performance degradation of UWSNs in terms of network lifetime and throughput. In this paper, we address the energy hole creation issue in depth-based routing techniques, and devise a technique to overcome the deficiencies in existing techniques. Besides addressing the energy hole issue, the proposition of a coverage hole repair technique is also part of this paper. In areas of the dense deployment, sensing ranges of nodes redundantly overlap. Our proposed technique takes a benefit of redundant overlapping and repairs a coverage hole during network operation. Simulation results show that our two techniques cohesively conserve nodes' energy, which ultimately maximizes the network lifetime and throughput at the cost of increased delay.
... This protocol can cope with transmitting bursty traffic in a duty-cycled UWSNs and deliver traffic efficiently. In paper [15], to address the energy hole issues for most of depth relied on UWSNs routing protocol, Kamran et al. investigate the depth based technologies to enhance the energy efficient for the routing protocol. In addition, Rachman et al. measure the energy consumption at the nodes in UWSNs through simulation [16]. ...
... × N wires × L link (15) where L wires is the length of the bus cable, N wires is the amount of the bus cable, L link is the data load. In our MMSL model, since the multi-sensor modules share one cable, N wires is set to be 1. ...
Article
Full-text available
In this paper, we propose a novel design named multi-module separated linear (MMSL) underwater sensor node. Traditionally, the design of the underwater sensor node is the all-in-one type. The process module, sensor module, and communication module are integrated into one module, and generally, one node carries only one communication module. Therefore, the coverage of the Underwater Wireless Sensor Network (UWSNs) mainly rely on the number of the underwater sensor nodes, and when the scale of the UWSNs increases, the communication delay rapidly increases. MMSL underwater sensor node is composed of multiple traditional sensor modules and common communication modules. With the deployment of this type of new nodes, the completed acoustic channel would be transformed into the hybrid channel which is a combination of the acoustic and cable channel. We compare the coverage rate, data transmission energy loss, and delivery delay of this MMSL sensor node composed network with traditional UWSNs as well. According to the theoretical analysis and the simulation experiments based on the MATLAB platform and the UWSNs, which consist of MMSL sensor nodes, have distinct advantage in coverage rate and perform better on communication energy consumption and delivery delay.
... The conventional routing protocols that cope with energy holes require that the localization information of an energy hole is known [9,10]. However, localization is a cumbersome and challenging task, as nodes change their positions with water currents. ...
Article
Full-text available
Interference and energy holes formation in underwater wireless sensor networks (UWSNs) threaten the reliable delivery of data packets from a source to a destination. Interference also causes inefficient utilization of the limited battery power of the sensor nodes in that more power is consumed in the retransmission of the lost packets. Energy holes are dead nodes close to the surface of water, and their early death interrupts data delivery even when the network has live nodes. This paper proposes a localization-free interference and energy holes minimization (LF-IEHM) routing protocol for UWSNs. The proposed algorithm overcomes interference during data packet forwarding by defining a unique packet holding time for every sensor node. The energy holes formation is mitigated by a variable transmission range of the sensor nodes. As compared to the conventional routing protocols, the proposed protocol does not require the localization information of the sensor nodes, which is cumbersome and difficult to obtain, as nodes change their positions with water currents. Simulation results show superior performance of the proposed scheme in terms of packets received at the final destination and end-to-end delay.
... To design a communication system, we have to consider these features in UWSNs [3]: (1) low available bandwidth; in UWSNs, the available bandwidth is less than 100 KHz; (2) dynamic topology; the underwater sensor nodes usually move with water current, which leads to the uncertainty of neighbor nodes and varied topology; (3) limited energy; underwater sensor nodes are powered by batteries which are hard to replace or recharge. Once the power runs out, the sensor node is considered to be dead [4]; (4) unknown position; positioning technology used on land, such as GPS, is not applicable in UWSNs. ...
Article
Underwater wireless sensor networks (UWSNs) are featured by long propagation delay, limited energy, narrow bandwidth, high BER (Bit Error Rate) and variable topology structure. These features make it very difficult to design a short delay and high energy-efficiency routing protocol for UWSNs. In this paper, a routing protocol independent of location information is proposed based on received signal strength (RSS), which is called RRSS. In RRSS, a sensor node firstly establishes a vector from the node to a sink node; the length of the vector indicates the RSS of the beacon signal (RSSB) from the sink node. A node selects the next-hop along the vector according to RSSB and the RSS of a hello packet (RSSH). The node nearer to the vector has higher priority to be a candidate next-hop. To avoid data packets being delivered to the neighbor nodes in a void area, a void-avoiding algorithm is introduced. In addition, residual energy is considered when selecting the next-hop. Meanwhile, we establish mathematic models to analyze the robustness and energy efficiency of RRSS. Lastly, we conduct extensive simulations, and the simulation results show RRSS can save energy consumption and decrease end-to-end delay.
... In [15], the authers analyzed the evolution of certain UWSNs routing protocols like VBF, DBR, H2-DAB, QELAR [16] etc. in terms of their localization , energy minimization and holding time calculation techniques. Each protocol follows certain goals i.e. minimization of energy consumption, communication latency improvement, robustness and scalability etc. ...
Article
Full-text available
The protocols proposed for Underwater Wireless Sensor Networks have addressed various issues concerning the unique characteristics of the Underwater Wireless Sensor Networks environment. Particularly, improving the network lifetime and balanced energy consumption is an important issue in Underwater Wireless Sensor Networks. Replacement of the batteries of underwater nodes is very expensive due to harsh underwater environment. In order to, handle the problem of network life time, balanced energy consumption and unreliable link quality; many authors proposed multi hop data delivery routing protocols like, Depth Based Routing (DBR) protocols, Energy Efficient Depth Based Routing (EEDBR) protocol and Hop by Hop Dynamic Addressing Based (H2-DAB) protocols. However, in such multi hop routing protocols the initial energy of nodes is same and the ones nearer to sink drain energy quickly as compared to distant nodes. In this paper, we implemented our proposed protocol called Advance Energy Efficient Depth Based Routing protocol (AEEDBR) which not only distributes energy evenly throughout the network for all the nodes but also helps to improve network lifetime, as nodes nearer to sink consume more energy than nodes away from sink in DBR protocol and EEDBR Routing protocol. Moreover, our proposed protocol does not require any location information of nodes and only a limited number of nodes are involved during the packet forwarding process
... In [15], the authers analyzed the evolution of certain UWSNs routing protocols like VBF, DBR, H2-DAB, QELAR [16] etc. in terms of their localization , energy minimization and holding time calculation techniques. Each protocol follows certain goals i.e. minimization of energy consumption, communication latency improvement, robustness and scalability etc. ...
Article
Full-text available
The protocols proposed for Underwater Wireless Sensor Networks have addressed various issues concerning the unique characteristics of the Underwater Wireless Sensor Networks environment. Particularly, improving the network lifetime and balanced energy consumption is an important issue in Underwater Wireless Sensor Networks. Replacement of the batteries of underwater nodes is very expensive due to harsh underwater environment. In order to, handle the problem of network life time, balanced energy consumption and unreliable link quality; many authors proposed multi hop data delivery routing protocols like, Depth Based Routing (DBR) protocols, Energy Efficient Depth Based Routing (EEDBR) protocol and Hop by Hop Dynamic Addressing Based (H2-DAB) protocols. However, in such multi hop routing protocols the initial energy of nodes is same and the ones nearer to sink drain energy quickly as compared to distant nodes. In this paper, we implemented our proposed protocol called Advance Energy Efficient Depth Based Routing protocol (AEEDBR) which not only distributes energy evenly throughout the network for all the nodes but also helps to improve network lifetime, as nodes nearer to sink consume more energy than nodes away from sink in DBR protocol and EEDBR Routing protocol. Moreover, our proposed protocol does not require any location information of nodes and only a limited number of nodes are involved during the packet forwarding process.
... Acoustic models are also used to detect energy holes in network. Latif et.al [12] propose energy hole minimization technique in UWSNs by using the acoustic models. Using the acoustic models, surveys are also conducted in order to achieve minimization of delay in UWSN. ...
Conference Paper
Depth-based routing protocols play a key role in assuming realistic approach by considering the continuous node movement in aqueous environment. The performance attributes of depth-based routing protocols highly depend upon the depth information of sensor nodes. Although this information is not prioritized by all acoustic models to estimate channel conditions, however, some notable models consider depth information of nodes. In this paper, we discuss the analysis of two major acoustic propagation models of Thorp and Monterey-Miami Parabolic Equation (MMPE) in predicting transmission losses with four notable depth-based routing techniques of Depth-Based Routing (DBR), Energy Efficient Depth-Based Routing (EEDBR), Adaptive Mobility of Courier nodes in Threshold-optimized Dbr (AMCTD) and Improved Adaptive Mobility of Courier nodes in Threshold-optimized Dbr (IAMCTD). We highlight the complexity and accuracy of these models in estimating the performance of higher layer protocols. Simulations show that physical layer parameters highly affect the performance of routing layer protocols as predicted by later propagation models. Results also prove that distant transmissions cause high propagation losses which are overcome by latest depth-based routing protocols. These protocols analyze the results of MMPE model to enhance upper channel limits and network lifetime.
Article
Full-text available
The major difference between underwater sensor networks (UWSNs) and terrestrial sensor networks is the use of acoustic signals as a communication medium rather than radio signals. The main reason behind this is the poor performance of radio signals in water. UWSNs have some distinct characteristics which makes them more research-oriented which is the large propagation delay, high error rate, low bandwidth, and limited energy. UWSNs have their application in the field of oceanographic, data collection, pollution monitoring, off-shore exploration, disaster prevention, assisted navigation, tactical surveillance, etc. In UWSNs the main advantages of protocol design are to a reliable and effective data transmission from source to destination. Among those, energy efficiency plays an important role in underwater communication. The main energy sources of UWSNs are batteries which are very difficult to replace frequently. There are two popular underwater protocols that are DBR and EEDBR. DBR is one of the popular routing techniques which don't use the full dimensional location information. In this article the authors use an efficient area localization scheme for UWSNs to minimize the energy hole created. Rather than finding the exact sensor position, this technique will estimate the position of every sensor node within certain area. In addition to that the authors introduced a RF based location finding and multilevel power transmission scheme. Simulation results shows that the proposed scheme produces better result than its counter parts.
Article
Full-text available
In this paper, we discuss a 3-dimensional localization sensor node using EM waves (Electromagnetic waves) with RSSI (Received Signal Strength Indicator). Generally EM waves cannot be used in underwater environment, because the signal is highly attenuated by the water medium according to the distance. Although the signal quickly reduces in underwater, the reducing tendency is very clear and uniform. Hence EM waves have possibility as underwater distance sensors. The authors have verified the possibility by theory and several experiments, and developed calibration methods in case of linear and planer environment. For 3-dimensional localization in underwater, it must be known antenna's radiation pattern property in electric plane(called E-plane). In this paper, we proceed experiments to verify attenuation tendency with z axis movement, PLF (Polarization Loss Factor) and ILF (Inclination Loss Factor) with its theoretical approach.
Article
Full-text available
Recently, underwater wireless sensor networks (UWSNs) have attracted much research attention from both academia and industry, in order to explore the vast underwater environment. UWSNs have peculiar characteristics; that is, they have large propagation delay, high error rate, low bandwidth, and limited energy. Therefore, designing network/routing protocols for UWSNs is very challenging. Also, in UWSNs, improving the energy efficiency is one of the most important issues since the replacement of the batteries of underwater sensor nodes is very expensive due to the unpleasant underwater environment. In this paper, we therefore propose an energy efficient routing protocol, named (energy-efficient depth-based routing protocol) EEDBR for UWSNs. EEDBR utilizes the depth of sensor nodes for forwarding data packets. Furthermore, the residual energy of sensor nodes is also taken into account in order to improve the network lifetime. Based on the comprehensive simulation using NS2, we observe that EEDBR contributes to the performance improvements in terms of the network lifetime, energy consumption, and end-to-end delay. A previous version of this paper was accepted in AST-2011 conference.
Article
Full-text available
In dense underwater sensor networks (UWSN), the major confronts are high error probability, incessant variation in topology of sensor nodes, and much energy consumption for data transmission. However, there are some remarkable applications of UWSN such as management of seabed and oil reservoirs, exploration of deep sea situation and prevention of aqueous disasters. In order to accomplish these applications, ignorance of the limitations of acoustic communications such as high delay and low bandwidth is not feasible. In this paper, we propose Adaptive mobility of Courier nodes in Threshold-optimized Depth-based routing (AMCTD), exploring the proficient amendments in depth threshold and implementing the optimal weight function to achieve longer network lifetime. We segregate our scheme in 3 major phases of weight updating, depth threshold variation and adaptive mobility of courier nodes. During data forwarding, we provide the framework for alterations in threshold to cope with the sparse condition of network. We ultimately perform detailed simulations to scrutinize the performance of our proposed scheme and its comparison with other two notable routing protocols in term of network lifetime and other essential parameters. The simulations results verify that our scheme performs better than the other techniques and near to optimal in the field of UWSN.
Conference Paper
Full-text available
IEEE 802.15.4 standard is specifically designed for low Rate Wireless Personal Area Network (LR-WPAN) with low data rate and low power capabilities. Due to very low power consumption with duty cycle even less than 0.1, the standard is being widely applied in Wireless Sensor Networks applications. It operates in Beacon and Non Beacon enabled modes. During Beacon enabled mode, it has Contention Access Period (CAP) and optional Contention Free Period. We have analyzed its performance during CAP where slotted CSMA/CA algorithm is used. The performance analysis includes channel access busy, transmission failure chances along with reliability and throughput against all three frequency bands with load variation.
Article
Full-text available
From energy conservation perspective in Wireless Sensor Networks (WSNs), clustering of sensor nodes is a challenging task. Clustering technique in routing protocols play a key role to prolong the stability period and lifetime of the network. In this paper, we propose and evaluate a new routing protocol for WSNs. Our protocol; Divide-and-Rule (DR) is based upon static clustering and dynamic Cluster Head (CH) selection technique. This technique selects fixed number of CHs in each round instead of probabilistic selection of CH. Simulation results show that DR protocol outperform its counterpart routing protocols.
Conference Paper
Full-text available
In this paper, we tackle one fundamental problem in Underwater Sensor Networks (UWSNs): robust, scalable and energy efficient routing. UWSNs are significantly different from terrestrial sensor networks in the following aspects: low bandwidth, high latency, node float mobility (resulting in high network dynamics), high error probability, and 3-dimensional space. These new features bring many challenges to the network protocol design of UWSNs. In this paper, we propose a novel routing protocol, called vector-based forwarding (VBF), to provide robust, scalable and energy efficient routing. VBF is essentially a position-based routing approach: nodes close to the “vector” from the source to the destination will forward the message. In this way, only a small fraction of the nodes are involved in routing. VBF also adopts a localized and distributed self-adaptation algorithm which allows nodes to weigh the benefit of forwarding packets and thus reduce energy consumption by discarding the low benefit packets. Through simulation experiments, we show the promising performance of VBF.
Conference Paper
Full-text available
This paper investigates a fundamental networking problem in underwater sensor networks: robust and energy-efficient routing. We present an adaptive location-based routing protocol, called hop-by-hop vector-based forwarding (HH-VBF). It uses the notion of a "routing vector" (a vector from the source to the sink) acting as the axis of the "routing pipe", similar to the vector based forward (VBF) routing in the work of P. Xie, J.-H. Cui and L. Lao (VBF: Vector-Based Forwarding Protocol for Underwater Sensor Networks. Technical report, UCONN CSE Technical Report: UbiNet-TR05-03 (BECAT/CSE-TR-05-6), Feb. 2005). Unlike the original VBF approach, however, HH-VBF suggests the use of a routing vector for each individual forwarder in the network, instead of a single network-wide source-to-sink routing vector. By the creation of the hop-by-hop vectors, HH-VBF can overcome two major problems in VBF: (1) too small data delivery ratio for sparse networks; (2) too sensitive to "routing pipe" radius threshold. We conduct simulations to evaluate HH-VBF, and the results show that HH-VBF yields much better performance than VBF in sparse networks. In addition, HH-VBF is less sensitive to the routing pipe radius threshold. Furthermore, we also analyze the behavior of HH-VBF and show that assuming proper redundancy and feedback techniques, HH-VBF can facilitate the avoidance of any "void" areas in the network.
Conference Paper
Full-text available
For large wireless sensor networks, identifying the exact location of every sensor may not be feasible and the cost may be very high. A coarse estimate of the sensors' locations is usually sufficient for many applications. In this paper, we propose an efficient Area Localization Scheme (ALS) for underwater sensor networks. This scheme tries to estimate the position of every sensor within a certain area rather than its exact location. The granularity of the areas estimated for each node can be easily adjusted by varying system parameters. All the complex calculations are handled by the powerful sinks instead of the sensors. This reduces the energy consumed by the sensors and helps extend the lifetime of the network.
Article
Full-text available
In this paper, a new wireless sensor network architecture is introduced for underwater surveillance systems where sensors lie in surface buoys when nodes are first deployed. After deployment, sensors are lowered to various depths selected by our scheme such that the maximum coverage of the three dimensional sensor space is maintained. Each node has multiple microsensors of various types; acoustic, magnetic, radiation and mechanical. A classification based data mining scheme based on the readings of these sensor types detects and classifies submarines, small delivery vehicles, mines and divers.
Conference Paper
Full-text available
In this paper, architectures for two-dimensional and three -dimensional underwater sensor networks are discussed. A detailed overview on the current solutions for medium access control, network, and transport layer protocols are given and open research issues are dis- cussed.
Article
Cluster based routing technique is most popular routing technique in Wireless Sensor Networks (WSNs). Due to varying need of WSN applications efficient energy utilization in routing protocols is still a potential area of research. In this research work we introduced a new energy efficient cluster based routing technique. In this technique we tried to overcome the problem of coverage hole and energy hole. In our technique we controlled these problems by introducing density controlled uniform distribution of nodes and fixing optimum number of Cluster Heads (CHs) in each round. Finally we verified our technique by experimental results of MATLAB simulations.
Article
SUMMARY Recently, underwater wireless sensor networks (UWSNs) have attracted much research attention to support various applications for pollution monitoring, tsunami warnings, offshore exploration, tactical surveillance, etc. However, because of the peculiar characteristics of UWSNs, designing communication protocols for UWSNs is a challenging task. Particularly, designing a routing protocol is of the most importance for successful data transmissions between sensors and the sink. In this paper, we propose a reliable and energy-efficient routing protocol, named R-ERP2R (Reliable Energy-efficient Routing Protocol based on physical distance and residual energy). The main idea behind R-ERP2R is to utilize physical distance as a routing metric and to balance energy consumption among sensors. Furthermore, during the selection of forwarding nodes, link quality towards the forwarding nodes is also considered to provide reliability and the residual energy of the forwarding nodes to prolong network lifetime. Using the NS-2 simulator, R-ERP2R is compared against a well-known routing protocol (i.e. depth-based routing) in terms of network lifetime, energy consumption, end-to-end delay and delivery ratio. The simulation results proved that R-ERP2R performs better in UWSNs.Copyright © 2012 John Wiley & Sons, Ltd.
Conference Paper
Cluster based routing technique is most popular routing technique in Wireless Sensor Networks (WSNs). Due to varying need of WSN applications efficient energy utilization in routing protocols is still a potential area of research. In this research work we introduced a new energy efficient cluster based routing technique. In this technique we tried to overcome the problem of coverage hole and energy hole. In our technique we controlled these problems by introducing density controlled uniform distribution of nodes and fixing optimum number of Cluster Heads (CHs) in each round. Finally we verified our technique by experimental results of MATLAB simulations.
Conference Paper
We propose a connectivity-based routing protocol (named CRP) for underwater wireless sensor networks (UWSNs). CRP considers the reliability issue due to high error rate in UWSNs. Hence, during forwarding, a node with the highest connectivity to the sink is selected as a next forwarding node. Using the NS-2 simulator, CRP is compared against a localization-free routing protocol in UWSNs (i.e. H2-DAB). Simulation results prove that CRP shows increased performance improvements over H2-DAB.
Article
Underwater Wireless Sensor Networks are significantly different from terrestrial sensor networks due to peculiar characteristics of low bandwidth, high latency, limited energy, node float mobility and high error probability. These features bring many challenges to the network protocol design of UWSNs. Several routing protocols have been developed in recent years for these networks. One of the major difficulties in comparison and validation of the performance of these proposals is the lack of a common standard to model the acoustic propagation in the harsh underwater environment. In this paper we analyze the evolution of certain underwater routing protocols like VBF, DBR, H2-DAB, QELAR etc. in terms of their localization techniques, energy minimization characteristics and holding time calculations. The design of each protocol follows certain goals i.e. reduction of energy consumption, improvement of communication latency, achievement of robustness and scalability etc. This paper examines the main approaches and challenges in the design and implementation of underwater sensor networks. The detailed descriptions of the selected protocols contribute in understanding the direction of the current research on routing layer in UWSN.
Article
In this paper, we present a comprehensive study of Medium Access Control (MAC) protocols developed for Wireless Body Area Networks (WBANs). In WBANs, small batteryoperated on-body or implanted biomedical sensor nodes are used to monitor physiological signs such as temperature, blood pressure, ElectroCardioGram (ECG), ElectroEncephaloGraphy (EEG) etc. We discuss design requirements for WBANs with major sources of energy dissipation. Then, we further investigate the existing designed protocols for WBANs with focus on their strengths and weaknesses. Paper ends up with concluding remarks and open research issues for future work.
Article
Extensive energy is consumed by Transceiver communication operation [1]. Existing research on MAC layer focuses to maximize battery-powered sensor node's life. Bottleneck of MAC layer protocol design for WBAN is to achieve high reliability and energy minimization. Majority of MAC protocols designed for WBANs are based upon TDMA approach. However, a new protocol needs to be defined to achieve high energy efficiency, fairness and avoid extra energy consumption due to synchronization.
Chapter
Recently, Underwater Wireless Sensor Networks (UWSNs) have attracted much research attention from both academia and industry, in order to explore the vast underwater environment. However, designing network protocols is challenging in UWSNs since UWSNs have peculiar characteristics of large propagation delay, high error rate, low bandwidth and limited energy. In UWSNs, improving the energy efficiency is one of the most important issues since the replacement of the batteries of such nodes is very expensive due to harsh underwater environment. Hence, in this paper, we propose an energy efficient routing protocol, named EEDBR (Energy-Efficient Depth Based Routing protocol) for UWSNs. Our proposed protocol utilizes the depth of the sensor nodes for forwarding the data packets. Furthermore, the residual energy of the sensor nodes is also taken into account in order to improve the network life-time. Based on the comprehensive simulation using NS2, we observe that our proposed routing protocol contributes to the performance improvements in terms of the network lifetime, energy consumption and end-to-end delay. KeywordsUnderwater wireless sensor networks–routing–network life-time–residual energy
Conference Paper
Underwater wireless sensor Networks (UWSN) will provide a variety of attractive working fields such as aquaculture, offshore exploitation, biological monitoring as well as water and seafloor pollution, seismic activity and ocean currents. A practical implementation of these applications will require spreading an important number of nodes to facilitate underwater monitoring by means of data acquiring, so it becomes a challenge to develop simple and reliable modem architectures to reduce both the cost in components and the developing time, still being efficient and robust. Moreover power consumption must be also considered due to energy harvesting difficulties in an underwater environment. This work is focused in the design and implementation of a low cost and energy efficient underwater modem. The paper presents a new acoustic modem design based on an original signal-conditioning model optimally adapted to commercial echo sounder based piezoelectric transducers. It represents a very low-cost solution with a power consumption level similar to current terrestrial wireless sensor networks. The modulation and demodulation algorithms are essential to define the modem architecture. In this work, they have been adapted to a low power microcontroller processing capabilities. The proposed modem architecture includes an 8-bit microcontroller and few external analog components. A binary Coherent-FSK modulation has been chosen because it is more efficient in terms of bandwidth than a non-coherent FSK. Coherent FSK modulation algorithm is quite simple, and can be easily implemented in an 8-bit microcontroller with negligible execution time. Demodulation algorithm is more complex and needs a low-power solution. The paper investigates different alternatives, obtaining a new optimal solution including an additional specific processing unit to the microprocessor core. Compared with previous researches that used microcontrollers, the presented approach also improves energy efficiency - - without lowering bit rate and bandwidth efficiency. The design has a variable gain reception to measure precisely the incoming signal level and obtaining signal quality indicators similar to RSSI used in wireless RF sensor networks. The circuit has been simulated and experimentally tested too with a prototype. Several tests have been carried out using the different alternatives presented. The goal of the first experiments was to characterize the frequency response of the transducers, and validate acoustic wave generation and amplification models obtained by means of simulation. Measurements were also taken to obtain receiver sensitivity and communication efficiency to power variations. Efficient design of both power amplifier and receiver analog processing stages, combined with optimal microcontroller power saving modes has extended estimated battery. As a conclusion, a worthwhile modem has been designed with the following advantages: Ultra-Low power consumption, a small form factor and a low final cost which enable future low cost deployment of underwater sensor networks.
Article
Underwater sensor networks find applications in oceanographic data collection, pollution monitoring, offshore exploration, disaster prevention, assisted navigation, and tactical surveillance. In this paper, deployment strategies for two-dimensional and three-dimensional communication architectures for underwater acoustic sensor networks are proposed, and a mathematical deployment analysis for both architectures is provided. The objective is to determine the minimum number of sensors to be deployed to achieve optimal sensing and communication coverage, which are dictated by application requirements; provide guidelines on how to choose the optimal deployment surface area, given a target body of water; study the robustness of the sensor network to node failures, and provide an estimate of the number of redundant sensor nodes to be deployed to compensate for potential failures.
Conference Paper
Providing scalable and ecient routing services in underwater sensor net- works (UWSNs) is very challenging due to the unique characteristics of UWSNs. Firstly, UWSNs often employ acoustic channels for communications because radio signals do not work well in water. Compared with radio-frequency channels, acous- tic channels feature much lower bandwidths and several orders of magnitudes longer propagation delays. Secondly, UWSNs usually have very dynamic topology as sen- sors move passively with water currents. Some routing protocols have been proposed to address the challenging problem in UWSNs. However, most of them assume that the full-dimensional location information of all sensor nodes in a network is known in prior through a localization process, which is yet another challenging issue to be solved in UWSNs. In this paper, we propose a depth-based routing (DBR) protocol. DBR does not require full-dimensional location information of sensor nodes. Instead, it needs only local depth information, which can be easily obtained with an inex- pensive depth sensor that can be equipped in every underwater sensor node. A key advantage of our protocol is that it can handle network dynamics eciently with- out the assistance of a localization service. Moreover, our routing protocol can take advantage of a multiple-sink underwater sensor network architecture without intro- ducing extra cost. We conduct extensive simulations. The results show that DBR can achieve very high packet delivery ratios (at least 95%) for dense networks with only small communication cost.
Conference Paper
In this paper, we study the localization problem in large-scale underwater sensor networks. The adverse aqueous environ- ments, the node mobility, and the large network scale all pose new challenges, and most current localization schemes are not applicable. We propose a hierarchical approach which divides the whole localization process into two sub-processes: anchor node localization and ordinary node localization. Many existing techniques can be used in the former. For the ordinary node localization process, we propose a distributed localization scheme which novelly integrates a 3-dimensional Euclidean distance estimation method with a recursive location estimation method. Simulation results show that our proposed solution can achieve high localization coverage with relatively small localization error and low communication overhead in large-scale 3-dimensional underwater sensor networks.
Conference Paper
Multi-hop transmission is considered for large coverage ar- eas in bandwidth-limited underwater acoustic networks. In this paper, we present a scalable routing technique based on location information, and optimized for minimum energy per bit consumption. The proposed Focused Beam Rout- ing (FBR) protocol is suitable for networks containing both static and mobile nodes, which are not necessarily synchro- nized to a global clock. A source node must be aware of its own location and the location of its final destination, but not those of other nodes. The FBR protocol can be defined as a cross-layer ap- proach, in which the routing protocol, the medium access control and the physical layer functionalities are tightly cou- pled by power control. It can be described as a distributed algorithm, in which a route is dynamically established as the data packet traverses the network towards its final destina- tion. The selection of the next relay is made at each step of the path after suitable candidates have proposed themselves. The system performance is measured in terms of energy per bit consumption and average packet end-to-end delay. The results are compared to those obtained using pre-establi- shed routes, defined via Dijkstra's algorithm for minimal power consumption. It is shown that the protocol's perfor- mance is close to the ideal case, as the additional burden of dynamic route discovery is minimal.
Conference Paper
In this paper, we present a robust, decentralized approach to RF-based location tracking. Our system, called MoteTrack, is based on low-power radio transceivers coupled with a modest amount of computation and storage capabilities. MoteTrack does not rely upon any back-end server or network infrastructure: the location of each mobile node is computed using a received radio signal strength signature from numerous beacon nodes to a database of signatures that is replicated across the beacon nodes themselves. This design allows the system to function despite significant failures of the radio beacon infrastructure. In our deployment of MoteTrack, consisting of 20 beacon nodes distributed across our Computer Science building, we achieve a 50th percentile and 80th percentile location-tracking accuracy of 2 meters and 3 meters respectively. In addition, MoteTrack can tolerate the failure of up to 60% of the beacon nodes without severely degrading accuracy, making the system suitable for deployment in highly volatile conditions. We present a detailed analysis of MoteTrack’s performance under a wide range of conditions, including variance in the number of obstructions, beacon node failure, radio signature perturbations, receiver sensitivity, and beacon node density.
Divide-and-rule scheme for energy efficient routing in wireless sensor networks
  • K Latif
  • A Ahmad
  • N Javaid
  • Z Khan
  • N Alrajeh