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Improved Interference Aware EEDBR Protocol for Underwater Wireless Sensor Networks
... Based on the DBR, Mohammadi et al. in [10] proposed the Fuzzy DBR (FDBR) which selects forwarding nodes based on the number of hops, depth, and energy information, improving the energy efficiency and reducing the end-to-end delay. There are also many similar routing protocols, such as the VARP [11], GEDAR [12], iIA-EEDBR [13], EECOR [14], EEIRA [15], and so on. Similarly, the underwater acoustic routing design based on cooperative communication, such as CoDBR [42], Co-UWSN [43], SPARCO [44], RBCMIC [45], S-DCC [4], etc., also mostly considers end-to-end delay, network lifetime, and energy consumption. ...
... Since the residual energy of nodes is an important factor affecting path selection, the initial energy setting of nodes will affect the choice of path according to Eqs. (13) and (14). It is known from [35] that the energy related parameter for the ACAR protocol is L k,best = 5657436.463287456, ...
For a given source-destination pair in multi-hop underwater acoustic sensor networks (UASNs), an optimal route is the one with the lowest energy consumptions that usually consists of the same relay nodes even under different transmission tasks. However, this will lead to the unbalanced payload of the relay nodes in the multi-hop UASNs and accelerate the loss of the working ability for the entire system. In this paper, we propose a node payload balanced ant colony optimal cooperative routing (PB-ACR) protocol for multi-hop UASNs, through combining the ant colony algorithm and cooperative transmission. The proposed PB-ACR protocol is a relay node energy consumption balanced scheme, which considers both data priority and residual energy of each relay node, aiming to reduce the occurrence of energy holes and thereby prolong the lifetime of the entire UASNs. We compare the proposed PB-ACR protocol with the existing ant colony algorithm routing (ACAR) protocol to verify its performances in multi-hop UASNs, in terms of network throughput, energy consumption, and algorithm complexity. The simulation results show that the proposed PB-ACR protocol can effectively balance the energy consumption of underwater sensor nodes and hence prolong the network lifetime.
... However, the selection of nodes with the lowest energy results in the early death of such nodes, which leads to significant packet drop as the network operates. The improved IA-IEEDBR (iIA-IEEDBR) protocol addresses the early death of low-energy nodes in the IA-IEEDBR protocol [25]. It divides the network into four logical sections with each section having a header that controls the death of nodes. ...
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.
... The authors in [19] propose an improved interference-aware EEDBR (iIA-EEDBR) protocol to avoid creation of holes and prolong network lifetime and the number of packets received at the sink. Half of the nodes are deployed in sensing mode and the rest in sleeping mode. ...
Interference-aware routing protocol design for underwater wireless sensor networks (UWSNs) is one of the key strategies in reducing packet loss in the highly hostile underwater environment. The reduced interference causes efficient utilization of the limited battery power of the sensor nodes that, in consequence, prolongs the entire network lifetime. In this paper, we propose an energy-efficient interference-aware routing (EEIAR) protocol for UWSNs. A sender node selects the best relay node in its neighborhood with the lowest depth and the least number of neighbors. Combination of the two routing metrics ensures that data packets are forwarded along the least interference paths to reach the final destination. The proposed work is unique in that it does not require the full dimensional localization information of sensor nodes and the network total depth is segmented to identify source, relay and neighbor nodes. Simulation results reveal better performance of the scheme than the counterparts DBR and EEDBR techniques in terms of energy efficiency, packet delivery ratio and end-to-end delay.
... In [17], the authors propose improved interference aware EEDBR (iIA-EEDBR) protocol for UWSNs. This selects forwarder node with high residual energy, least depth and less number of neighbors in its transmission range. ...
In this paper, depth and reliability aware delay 1 sensitive (DRADS), interference aware DRADS (iDRADS) and 2 cooperative iDRADS (Co-iDRADS) routing protocols are pro-3 posed for maximizing network good-put while minimizing end-4 to-end delay. We have introduced a new metric called depth 5 threshold to minimize the number of hops between source and 6 destination while ensuring successful packet delivery. Our inter-7 ference aware and cooperative routing based algorithms select 8 the best relay node at each hop. Extensive simulation results 9 validate that the proposed routing techniques perform better 10 than the selected existing ones in terms of good-put and energy 11 cost of the network. Index Terms—Underwater wireless sensor 12 networks, Depth, Cooperation, Reliability, Energy efficiency 13
... Author proposed IiA-EEDBR [4] (Improved Interference Aware EEDBR),In which forwarding node is selected based on least depth from the sink, high residual energy, as well as less number of neighbors. In IiA-EEDBR, network lifetime is improved and routing holes are minimized by deploying sleep nodes in UWSN. ...
Developing an energy efficient routing protocol for underwater wireless sensor networks (UWSNs) is a challenging task due to long propagation delay, low bandwidth, high error probability, and most importantly limited energy. Unlike terrestrial sensor networks, UWSN environment is harsh. Nodes are provided with limited energy. The replacement or charging of batteries is not an easy task. By minimizing number of transmissions and considering some time critical applications. We have proposed an enhanced energy efficient depth based routing protocol, EEEDBR, for UWSNs. EEEDBR, selects a forwarding node based on high residual energy, least depth from the sink. In EEEDBR network lifetime is increased by deploying idle nodes in the medium depth region. As, sensor nodes gets die earlier in low or medium depth region due to the additional relaying of data packets. Moreover, In our proposed scheme nodes can vary their transmission range up to a certain limit in order to find a suitable forwarding node.
Underwater wireless sensor network (UWSN) features many unique characteristics, including slow propagation speed, high end-to-end delay, low available bandwidth, variable link quality, and energy constraint. All these problems pose a big challenge to devise a transmission efficient, energy-saving, and low delay routing protocol for UWSNs. In this paper we devise a relative distance based forwarding (RDBF) routing protocol, which aims to provide transmission efficient, energy-saving, and low delay routing. We utilize a fitness factor to measure and judge the degree of appropriateness for a node to forward the packets. Under the limitations of the fitness factor, RDBF can confine the scope of the candidate forwarders and find the beneficial relays to forward packets. In this way, only a small fraction of nodes are involved in forwarding process, which can distinctly reduce the energy consumption. Moreover, using only the selected beneficial nodes as forwarders can both enhance the transmission efficiency and reduce the end-to-end delay. This is because the distances of these nodes to the sink are the shortest and the hop counts of routing paths consisted by these nodes are minimum. We use the ns-2 based simulator to conduct our experiment; the results show that RDBF performs better in terms of packet delivery ratio, end-to-end delay, and energy efficiency.
The paper studies the distortion performance of multihop underwater acoustic sensor networks. The network is composed of bottom mounted sensor nodes and the sensor to sensor links experience Rician fading. The distortion is evaluated for the case when there is interference from other sensors in the network. The focus is on the sustainable number of hops in the network for a maximum allowed (target) route distortion requirement. Numerical examples are provided that illustrate the results of the analysis and the regions where the network operation is limited, namely, the coverage-limited region and the interference-limited region. The paper also considers the impact of retransmissions on the distortion performance. It is found that the network connectivity and robustness improve with automatic repeat request (ARQ). The improvements are manifested as a reduction of the regions of limited performance, that is, an increase of the region where the network exhibits full connectivity. The analysis results are illustrated through numerical examples.
In multi-hop underwater acoustic sensor networks (UWASNs), packet collisions due to hidden and local nodes adversely affect throughput, energy efficiency and end-to-end delay. Existing medium access control (MAC) protocols try to solve the problem by utilizing a single-phase contention resolution mechanism, which causes a large number of control packet exchanges and energy overhead. In this paper, we introduce a MAC protocol that splits this single-phase contention resolution mechanism into two phases to provide efficient multi-hop networking. In the first phase, local nodes are eliminated from the contention, and in the later phase, the adverse effects of hidden nodes are mitigated. This two-phased contention resolution provides higher energy efficiency, better throughput and shorter end-to-end delay, and it also enables adaptability for different network architectures. A probabilistic model of the proposed protocol is also developed to analyse the performance. The proposed protocol has been evaluated through quantitative analysis and simulation. Results obtained through quantitative analysis and simulation reveal that the proposed protocol achieves significantly better energy efficiency, higher and more stable throughput and lower end-to-end delay compared to existing protocols, namely T-Lohi and slotted floor acquisition multiple access (S-FAMA).
Designing an efficient deployment method to guarantee optimal monitoring quality is one of the key topics in underwater sensor networks. At present, a realistic approach of deployment involves adjusting the depths of nodes in water. One of the typical algorithms used in such process is the self-deployment depth adjustment algorithm (SDDA). This algorithm mainly focuses on maximizing network coverage by constantly adjusting node depths to reduce coverage overlaps between two neighboring nodes, and thus, achieves good performance. However, the connectivity performance of SDDA is irresolute. In this paper, we propose a depth adjustment algorithm based on connected tree (CTDA). In CTDA, the sink node is used as the first root node to start building a connected tree. Finally, the network can be organized as a forest to maintain network connectivity. Coverage overlaps between the parent node and the child node are then reduced within each sub-tree to optimize coverage. The hierarchical strategy is used to adjust the distance between the parent node and the child node to reduce node movement. Furthermore, the silent mode is adopted to reduce communication cost. Simulations show that compared with SDDA, CTDA can achieve high connectivity with various communication ranges and different numbers of nodes. Moreover, it can realize coverage as high as that of SDDA with various sensing ranges and numbers of nodes but with less energy consumption. Simulations under sparse environments show that the connectivity and energy consumption performances of CTDA are considerably better than those of SDDA. Meanwhile, the connectivity and coverage performances of CTDA are close to those depth adjustment algorithms base on connected dominating set (CDA), which is an algorithm similar to CTDA. However, the energy consumption of CTDA is less than that of CDA, particularly in sparse underwater environments.
With the rapid development of underwater acoustic modem technology, underwater acoustic sensor networks (UWASNs) have more applications in long-term monitoring of the deployment area. In the underwater environment, the sensors are costly with limited energy. And acoustic communication medium poses new challenges, including high path loss, low bandwidth, and high energy consumption. Therefore, designing transmission mechanism to decrease energy consumption and to optimize the lifetime of UWASN becomes a significant task. This paper proposes a balance transmission mechanism, and divides the data transmission process into two phases. In the routing set-up phase, an efficient routing algorithm based on the optimum transmission distance is present to optimize the energy consumption of the UWASN. And then, a data balance transmission algorithm is introduced in the stable data transmission phase. The algorithm determines one-hop or multihop data transmission of the node to underwater sink according to the current energy level of adjacent nodes. Furthermore, detailed theoretical analysis evaluates the optimum energy levels in the UWASNs with different scales. The simulation results prove the efficiency of the BTM.
Appropriate network design is very significant for Underwater Wireless Sensor Networks (UWSNs). Application-oriented UWSNs are planned to achieve certain objectives. Therefore, there is always a demand for efficient data routing schemes, which can fulfill certain requirements of application-oriented UWSNs. These networks can be of any shape, i.e., rectangular, cylindrical or square. In this paper, we propose chain-based routing schemes for application-oriented cylindrical networks and also formulate mathematical models to find a global optimum path for data transmission. In the first scheme, we devise four interconnected chains of sensor nodes to perform data communication. In the second scheme, we propose routing scheme in which two chains of sensor nodes are interconnected, whereas in third scheme single-chain based routing is done in cylindrical networks. After finding local optimum paths in separate chains, we find global optimum paths through their interconnection. Moreover, we develop a computational model for the analysis of end-to-end delay. We compare the performance of the above three proposed schemes with that of Power Efficient Gathering System in Sensor Information Systems (PEGASIS) and Congestion adjusted PEGASIS (C-PEGASIS). Simulation results show that our proposed 4-chain based scheme performs better than the other selected schemes in terms of network lifetime, end-to-end delay, path loss, transmission loss, and packet sending rate.
Underwater wireless sensor networks (UWSNs) have attracted significant research attention recently from both industry and academia. Due to the significantly differences from terrestrial wireless sensor networks, including slow propagation speed, high end-to-end delay, low available bandwidth, variable link quality and energy constraint, designing an efficient routing protocol for the underwater sensor networks is challenging. In this paper we devise a relative distance-based forwarding (RDBF) routing protocol, which always try to send the packets along an optimized path without constructing a communication path previously. To limit the scope of candidate forwarders and find the optimal relay, we utilize a fitness factor to measure and judge the degree of appropriateness for a node to forward the packets.
We propose forwarding-function (íµí°¹ íµí°¹) based routing protocol for underwater sensor networks (UWSNs): improved adaptive mobility of courier nodes in threshold-optimized depth-based-routing (iAMCTD). Unlike existing depth-based acoustic protocols, the proposed protocol exploits network density for time-critical applications. In order to tackle flooding, path loss, and propagation latency, we calculate optimal holding time (íµí°» íµí±) and use routing metrics: localization-free signal-to-noise ratio (LSNR), signal quality index (SQI), energy cost function (ECF), and depth-dependent function (DDF). Our proposal provides on-demand routing by formulating hard threshold (íµí°» th), soft threshold (íµí± th), and prime energy limit (íµí±
prime). Simulation results verify effectiveness and efficiency of the proposed iAMCTD.
In many Wireless Sensor Network (WSN) applications such as warning systems or healthcare services it is necessary to update the captured data with location information. A promising solution for statically deployed sensors is to benefit from mobile beacon assisted localization. The main challenge is to design and develop an optimum path planning mechanism for a mobile beacon to decrease the required time for determining location, increase the accuracy of the estimated position and increase the coverage. In this paper, we propose a novel superior path planning mechanism called Z-curve. Our proposed trajectory can successfully localize all deployed sensors with high precision and the shortest required time for localization. We also introduce critical metrics including the ineffective position rate for further evaluation of mobile beacon trajectories. In addition, we consider an accurate and reliable channel model which helps to provide more realistic evaluation. Z-curve is compared with five existing path planning schemes based on three different localization techniques such as Weighted Centroid Localization and trilateration with time priority and accuracy priority. Furthermore, the performance of the Z-curve is evaluated at the presence of obstacles and Z-curve obstacle-handling trajectory is proposed to mitigate the obstacle problem on localization. Simulation results show the advantages of our proposed path planning scheme over the existing schemes.
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.
We propose a path unaware layered routing protocol (PULRP) for dense underwater 3D sensor networks. An uplink transmission is considered, where a set of underwater sensor nodes report events to the sink node. PURLP algorithm consists of two phases. In the first phase (layering phase), a layering structure is presented which is a set of concentric spheres, around a sink node. The radius of the concentric spheres is chosen based on probability of successful packet forwarding as well as packet delivery latency. In the second phase (communication phase), we propose a method to choose the intermediate relay nodes and an on the fly routing algorithm for packet delivery from source node to sink node across the chosen relay nodes. The proposed algorithm, PULRP finds the routing path on the fly and hence it does not require any fixed routing table, localization or time synchronization processes. Our findings show that the proposed algorithm has a considerably better successful packet delivery rate compared to the under water diffusion (UWD) algorithm proposed in the paper by Lee et al. (2007) and Dijkstra's shortest path algorithm. In addition the delay involved in PULRP is comparable with that of UWD.
Deploying a multi-hop underwater acoustic sensor network (UASN) in a large area brings about new challenges in reliable data transmissions and survivability of network due to the limited underwater communication range/bandwidth and the limited energy of underwater sensor nodes. In order to address those challenges and achieve the objectives of maximization of data delivery ratio and minimization of energy consumption of underwater sensor nodes, this paper proposes a new underwater routing scheme, namely AURP (AUV-aided underwater routing protocol), which uses not only heterogeneous acoustic communication channels but also controlled mobility of multiple autonomous underwater vehicles (AUVs). In AURP, the total data transmissions are minimized by using AUVs as relay nodes, which collect sensed data from gateway nodes and then forward to the sink. Moreover, controlled mobility of AUVs makes it possible to apply a short-range high data rate underwater channel for transmissions of a large amount of data. To the best to our knowledge, this work is the first attempt to employ multiple AUVs as relay nodes in a multi-hop UASN to improve the network performance in terms of data delivery ratio and energy consumption. Simulations, which are incorporated with a realistic underwater acoustic communication channel model, are carried out to evaluate the performance of the proposed scheme, and the results indicate that a high delivery ratio and low energy consumption can be achieved.
In recent years, underwater acoustic sensor networks (UWSNs) are envisioned for different potential applications, ranging from long-term marine environmental monitoring, industrial instrumentation control, to military surveillance and security. Compared to wireless sensor networks (WSNs), energy-efficient data transmission becomes more critical in UWSNs due to non-rechargeable batteries of sensor nodes with limited amount of energies in long-term marine monitoring applications. Besides, in underwater acoustic communications, transmitting and receiving power levels dominate the energy consumption during the data transfer. Data packet retransmission caused by network deployment error increases the energy consumption and reduce the network lifetime. In this paper, we investigate a two-dimensional deployment strategy of UWSNs with a square grid topology. We present a mathematical model to study the deployment error of UWSNs. Based on this model, a parameter, i.e., α, is introduced to balance the network robustness and the energy consumption of sensor nodes. α is defined as the ratio of the transmission range of a sensor node to the distance between two closest adjacent sensor nodes. We report optimal values of α corresponding to this balance for different sizes of UWSNs.
Underwater Acoustic Sensor Networks (UASNs) are deemed to facilitate monitoring tasks in aquatic environment. However, battery resource limitation of sensor nodes leads to shorter network lifetime. Also, unbalanced energy consumption which contributes to limited network lifetime needs to be addressed. Therefore, data transmission technique should be designed to overcome energy dissipation and to optimize network lifetime. This paper presents an Efficient and Balanced Energy consumption Technique (EBET) for UASNs. EBET provision solution for the problems of direct transmission energy consumption over long distance. EBET initially establishes communication links between nodes on the basis of optimal distance threshold. The initial energy of sensor nodes is divided into Energy Level Numbers (ELNs) for balanced energy consumption. Then in data transmission phase, appropriate transmission mechanism is chosen on the basis of specified energy level numbers of sensor nodes. The sensor nodes choose data relay type in accordance to the difference in energy level numbers. Long distance direct data transmission is avoided by selecting high ELN node within transmission range. The effectiveness of EBET is validated through simulations.
Underwater wireless sensor networks (UWSNs) are meant to be deployed at the areas that need to be monitored continuously without the human assistance. Therefore, these networks are expected to stay operational for a longer period of time. However, sensor nodes in these networks are equipped with limited energy (e.g., battery) resources. Moreover, uneven energy consumption is one of the biggest challenges in UWSN because it leads to creation of energy holes and ultimately shorten network lifetime. This invites UWSN designers to introduce protocols that can minimize and balance energy consumption of nodes. This paper presents DB-EBH, a Depth-Based Energy-Balanced Hybrid routing protocol for UWSNs. Like EBH, DB-EBH is a hybrid approach which is based on direct and multihop communication. However, DB-EBH considers linear random deployment of nodes. It selects a priority neighbor node for data forwarding on the basis of its depth from the sink. Simulation results validate the performance of DB-EBH in terms of energy efficiency, network lifetime and throughput.
The unique characteristics of Underwater Wireless Sensor Networks (UWSNs) attracted the research community to explore different aspects of these networks. Routing is one of the most important and challenging function in UWSNs, for efficient data communication and longevity of sensor node's battery timing. Sensor nodes have energy constraint because replacing the batteries of sensor nodes is an expensive and tough task in harsh aqueous environment. Also interference is a major performance influencing factor. Providing solutions for interference-free communication are also essential. In this paper, we propose three energy-efficient and interference-aware routing protocols named as Inverse Energy Efficient Depth-Based Routing protocol (IEEDBR), Interference-Aware Energy Efficient Depth-Based Routing protocol (IA-EEDBR) and Interference-Aware Inverse Energy Efficient Depth-Based Routing protocol (IA-IEEDBR). Unlike EEDBR, IEEDBR protocol uses depth and minimum residual energy information for selecting data for-warder. While IA-EEDBR takes minimum number of neighbors for forwarder selection. IA-IEEDBR considers depth, minimum residual energy along with minimum number of neighbors for selection of forwarder. Our proposed schemes are validated through simulation and the results demonstrate better performance in terms of improved network lifetime, maximized throughput and reduced path loss.
We introduce a genetic algorithm-based topology control mechanism, named 3D-GA, for Autonomous Underwater Vehicles (AUVs) operating in Underwater Sensor Networks (UWSNs). Using limited information collected from a node's local neighbours, 3D-GA runs autonomously at each AUV and provides guidance for its speed and direction towards a uniform spatial distribution while maintaining network connectivity. Imprecise and limited neighbourhood knowledge could potentially disrupt convergence towards a uniform and stable spatial coverage. We demonstrate that AUVs running our 3D-GA create a highly resilient network that can adapt to changing conditions such as the addition, loss or malfunction of number of AUVs. We also show that the ambiguity in detecting neighbours' exact locations does not prevent 3D-GA from achieving a uniform coverage but requiring AUVs travel longer distances to stabilise. Our simulation software results verify that 3D-GA is an effective tool for providing a robust solution for volumetric spatial control of AUVs in UWSNs.
Underwater Wireless Sensor Networks (UWSNs) support various applications like pollution monitoring, tsunami warnings, off-shore exploration, tactical surveillance, etc. Distinctive features of UWSNs like low available bandwidth, large propagation delay, highly dynamic network topology, and high error probability pose many challenges for designing efficient and reliable com-munication protocols. In this paper, we propose an extension of IAMCTD (Improved Adaptive Mobility of Courier nodes in Threshold-optimized DBR protocol for UWSNs) that focuses on enhancing network reliability and throughput for critical-range based applications. Our scheme avoids control overhead that was present in IAMCTD for implementing changes in depth thresh-old. The movement pattern of courier nodes along with reducing communication burden on nodes increases throughput as well. Additionally, stability period is improved and node density per round remains comparatively high improving the overall network reliability. Based on the comprehensive simulations using MATLAB, we observe that our scheme improves the performance in terms of throughput and stability period. Moreover, comparatively higher network density per round is maintained and end-to-end delay is stabilized throughout the network lifetime. c ⃝ 2014 The Authors. Published by Elsevier B.V. Selection and peer-review under responsibility of Elhadi M. Shakshuki.
Providing an efficient communication for the underwater wireless sensor networks is a significant problem due to the unique characteristics of such environments. Radio signal cannot propagate well in deep water, and we have to replace this with the acoustic channel. This replacement results in many issues like high latency due to less propagation speeds, low bandwidths and high error probability. In addition, new features like node mobility with water currents and 3-dimensional space brings additional challenges to the underwater sensor network (UWSN) protocol design. Many routing protocols have been proposed for such environments but most of them considered that the complete dimensional location of all the sensor nodes is already known through a localization process, which itself is a challenging task in UWSNs. In this paper, we propose a novel routing protocol, called Hop-by-Hop Dynamic Addressing Based (H2-DAB), in order to provide scalable and time efficient routing. Our routing protocol will take advantage of the multiple-sink architecture of the underwater wireless sensor networks. The novelty of H2-DAB is that, it does not require any dimensional location information, or any extra specialized hardware compared to many other routing protocols in the same area. Our results show that H2-DAB effectively achieves the goals of higher data deliveries with optimal delays and energy consumptions.
Simulation is important in the study of underwater networking because of the difficulty and expense of performing experiments. Underwater acoustic propagation is influenced by a wide variety of environmental factors, rendering analytic models complex, inaccurate, or both. Therefore, simulations based on models are of uncertain utility. In contrast, this simulator uses measured impulse response, CTD, noise, and transmission loss data in an effort to more realistically simulate the channel. The application layer generates data packets whose modulated waveforms are “mixed” with the channel's properties and sent to a receiver implemented fully in software, where the simulated bit error rate (BER) is measured. For a shallow time-invariant test channel, this process results in a simulated BER that is, on average, within 3.34% of the true BER.
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.