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On Energy Efficiency in Underwater Wireless Sensor Networks with Cooperative Routing
Abstract
Abstract In this paper, we exploit cooperative communication for design- ing an energy efficient routing algorithm in Underwater Wireless Sensor Net- works (UWSNs). Each network node is equipped with a single omnidirectional antenna and multiple nodes coordinate while taking advantage of spatial di- versity. This research work is limited in scope to Amplify-and-Forward (AF) scheme at the relay node and Fixed Ratio Combining (FRC) strategy at the receiver node. Cooperative diversity at the physical layer and multi-hop rout- ing at the network layer enable us to formulate minimum energy routing as a joint optimization of the transmission power at physical layer and link selection at the network layer. Simulations results show that our proposed Cooperative Energy Efficient routing for UWSNs (Co-EEUWSN) performs better than the selected non-cooperative routing protocols (Depth-Based Routing (DBR) and Energy-Efficient DBR (EEDBR)) and Cooperative DBR (Co-DBR) in terms of packet delivery ratio, end-to-end delay, and energy efficiency.
... Recently more works were introduced on opportunistic data forwarding for UWSNs [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46]. The energy-efficient chain-based routing method had introduced in [32] for UWSNs. ...
... They designed BEAR in three phases such as initialization phase, the tree-building phase, and the data transmission phase. Cooperative communication had exploited in [42] to propose an energy-efficient algorithm for UWSNs. Each node had equipped with multiple node coordinates and an Omni directional antenna in the network. ...
... Similarly, the distance computation techniques may lead to void in the network [31][32][33][34][35][36]. Some other recently presented methods [37][38][39][40][41][42][43][44][45][46] were based on efficient route formation and data transmission via selecting the best relay nodes suffering from various challenges related to network scalability and performance reliability. Most of these protocols used a maximum of two parameters for forwarding relay selection like residual energy (commonly used) and either packet delivering probability or distance to sink. ...
The technology advancement in the Internet of Things (IoT) enables a variety of smart monitoring applications assisted by networks like Wireless Sensor Networks (WSNs) and Underwater WSNs (UWSNs). The IoT-UWSNs supported a wide range of applications such as underwater data collection, underwater equipment monitoring, underwater imaging, etc. The acoustic signals have been utilized for communication in IoT-UWSNs over radio signals and optical signals. Data transmission using acoustic signals is suffering from lower throughput, excessive energy consumption, long transmission delay, and lower network lifetime. Several data forwarding and clustering algorithms have recently been proposed to enhance UWSN's performances. This paper proposed a novel routing solution for energy and QoS-efficient data transmission from the underwater sensor node to the surface sink using Swarm Intelligence (SI). This protocol called Energy Optimization using Routing Optimization (EORO) protocol. To optimize the UWSNs performance, we used Effective Fitness Function-based Particle Swarm Optimization (EFF-PSO) to select the best forwarder node for data transmission. In EORO, forwarding relay nodes discovered by the intended source node using location information firstly. Then EFF-PSO algorithm is applied to select the optimal relay node considering the rich set of parameters. Four parameters of each forwarder node used for fitness computation as residual energy, packet transmission ability, node connectivity, and distance. These parameters are intelligently selected to avoid packet collisions to achieve energy consumption and delay reduction with higher throughput. An experimental result shows that the EORO protocol outperformed underlying routing techniques using throughput, energy consumption, delay, and Packet Delivery Ratio (PDR).
... Ahmed et al. [14] also proposed cooperative communication to build an energyefficient protocol for UWASNs, referred to as Cooperative Energy Efficient routing for UWSNs (Co-EEUWSN). In this protocol, all nodes of the UWASN contains a directional antenna, while several nodes coordinate with each other. ...
... At the relay, Co-EEUWSN employed the amplify-and-forward mechanism; however, at the receiving node, the fixed ratio combining was used. In a comparison of this scheme's results with those of EEDBR and cooperative DBR, Co-EEUWSN showed improved energy efficiency, decreased end-to-end delays, and enhanced throughput [14]. ...
... Based on the literature review, most researchers [9,10,14,15] use node depth as a parameter for data routing. However, they do not address node load balancing and the distribution of load when the sensor nodes are uneven. ...
In underwater acoustic sensor networks (UWASNs), nodes are either static or dynamic depending upon the network configuration and type of application. Direct or multi-hop transmissions are used to forward data toward the sink. Alternatively, sinks can also be mobile or static, depending on whether the application is real time or passive. The variety of nodes and sink deployments greatly affect the performance of routing protocols. In this chapter, we analyze the effects of node density and scalability on the performance of routing protocols in UWASNs. Two popular UWASNs protocols were selected for this purpose: the depth-based routing protocol (DBR) and energy-efficient depth-based routing protocol (EEDBR). DBR is a non-cluster-based technique that performs routing using only the depth of nodes, whereas EEDBR is a location-free scheme that uses both the depth and the residual energy of nodes to route data. The scalability of node deployment was used to check the efficiency of these schemes in the context of three parameters: packet delivery ratio, end-to-end delay, and path loss.
... As a consequence, to mitigate UWSN problems and provide better communication, some studies have been developed from the physical layer to the network layer. There are some work about developing acoustic modems to effectively utilize the channels [28,62,65], medium access control (see Sect. 2), and routing information between sensor nodes [10, 22-26, 54, 76, 84]. ...
... Ahmad et al. [2] also use, at the relay, an amplify-andforward method, to perform cooperative communication. At the receiver, they also apply a fixed ratio combining strategy. ...
The novel Underwater Wireless Sensor Network (UWSN) can contribute to monitor and explore aquatic environments. But, communicating in these environments is still hard and has many challenges. For example, optical and electromagnetic waves deteriorate from high-attenuation. Moreover, acoustic communication has a large packet error rate and low throughput. A large number of solutions to improve aquatic communication refers to routing protocols, medium access control protocols, and designing acoustic modems. Cooperative communication explores the broadcast nature of wireless transmission and enhances its performance. However, cooperative communication has not been fully explored in UWSNs. In this work, we present COPPER, a Cooperative Protocol for Pervasive Underwater Acoustic Networks. COPPER considers LLC and MAC sub-layers and operates synchronously or asynchronously over Time Division Multiple Access using a selective repeat ARQ scheme. COPPER exploits the broadcast nature of wireless communication and, sensor nodes that are idle can operate as a relay, enhancing communication by space diversity. Simulation results show that COPPER improves network performance. For example, the network goodput improves by 17% and the packet error rate decreases by 65%.
... Destination node receive data from two sources simultaneously and apply fixed ratio combining technique [13] to analyze and select the most accurate signal out of the two sources. For reliable and efficient communication in UWSNs, many cooperation based communication protocols have been suggested in the current literature [14][15][16][17] and in [18,19]. For example, [18] deployed a single relay node for cooperation however a single relay node quickly exhaust energy which decreases a network lifetime. ...
... In [16], authors used amplify and forward technique at relay nodes and Fixed Ratio Combining technique (FRC) technique at destination node to increase the efficient use of energy and balance the data transmission load in a network. This technique does not employ energy harvesting enabled relay nodes, as a result the technique puts extra data forwarding load on the relay nodes, resulting in decreased network life time. ...
Underwater sensor networks (UWSNs) are ad-hoc networks which are deployed at rivers, seas and oceans to explore and monitor the phenomena such as pollution control, seismic activities and petroleum mining etc. The sensor nodes of UWSNs have limited charging capabilities. UWSNs networks are generally operated under two deployment mechanisms i.e localization and non-localization based. However, in both the mechanisms, balanced energy utilization is a challenging issue. Inefficient usage of energy significantly affects stability period, packet delivery ratio, end-to-end delay, path loss and throughput of a network. To efficiently utilize and harvest energy, this paper present a novel scheme called EH-ARCUN (Energy Harvesting Analytical approach towards Reliability with Cooperation for UWSNs) based on cooperation with energy harvesting. The scheme employs Amplify-and-Forward (AF) technique at relay nodes for data forwarding and Fixed Combining Ratio (FCR) technique at destination node to select accurate signal. The proposed technique selects relay nodes among its neighbor nodes based on harvested energy level. Most cooperation-based UWSN routing techniques do not exhibit energy harvesting mechanism at the relay nodes. EH-ARCUN deploys piezoelectric energy harvesting at relay nodes to improve the working capabilities of sensors in UWSNs. The proposed scheme is an extension of our previously implemented routing scheme called ARCUN for UWSNs. Performance of the proposed scheme is compared with ARCUN and RACE (Reliability and Adaptive Cooperation for efficient Underwater sensor Networks) schemes in term of stability period, packet delivery ratio, network throughput and path loss. Extensive simulation results show that EH-ARCUN performs better than both previous schemes in terms of the considered parameters.
... In noncooperative algorithms, delivery through a single link consumes less energy and time than cooperative techniques. However, these algorithms are not reliable and have greater chances of packets loss [12]. A small obstacle may lead to data loss and failure. ...
... In noncooperative algorithms, delivery through a single link consumes less energy and time than cooperative techniques. However, these algorithms are not reliable and have greater chances of packets loss [12]. A small obstacle may lead to data loss and failure. ...
Designing an efficient, reliable, and stable algorithm
for underwater acoustic wireless sensor networks(UA-WSNs).
... Retransmission is not appropriate for data received over the same noisy link. Additionally, many antennas are expensive and impractical in the underwater environment [6]. Cooperation is the optimal strategy for ensuring reliable and effective communication in UAWSNs. ...
Underwater wireless sensor networks (UWSNs) contain sensor nodes that sense the data and then transfer them to the sink node or base station. Sensor nodes are operationalized through limited-power batteries. Therefore, improvement in energy consumption becomes critical in UWSNs. Data forwarding through the nearest sensor node to the sink or base station reduces the network's reliability and stability because it creates a hotspot and drains the energy early. In this paper, we propose the cooperative energy-efficient routing (CEER) protocol to increase the network lifetime and acquire a reliable network. We use the sink mobility scheme to reduce energy consumption by eliminating the hotspot issue. We have divided the area into multiple sections for better deployment and deployed the sink nodes in each area. Sensor nodes generate the data and send it to the sink nodes to reduce energy consumption. We have also used the cooperative technique to achieve reliability in the network. Based on simulation results, the proposed scheme performed better than existing routing protocols in terms of packet delivery ratio (PDR), energy consumption, transmission loss, and end-to-end delay.
... In [148] the author presented a cooperative and E2RP (CO-E2RP) for UWSNs. The repeater node is chosen from Tx anchor node to sensor Rx node, which is based on channel capacity and signal-to-noise ratio (SNR). ...
Underwater wireless sensor networks (UWSNs) have become highly efficient in performing different operations in oceanic environments. Compared to terrestrial wireless sensor networks (TWSNs), MAC and routing protocols in UWSNs are prone to low bandwidth, low throughput, high energy consumption, and high propagation delay. UWSNs are located remotely and do not need to operate with any human involvement. In UWSNs, the majority of sensor batteries have limited energy and very difficult to replace. The uneven use of energy resources is one of the main problems for UWSNs, which reduce the lifetime of the network. Therefore, an energy-efficient MAC and routing techniques are required to address the aforementioned challenges. Several important research projects have been tried to realize this objective by designing energy-efficient MAC and routing protocols to improve efficient data packet routing from Tx anchor node to sensor Rx node. In this article, we concentrate on discussing about different energy-efficient MAC and routing protocols which are presently accessible for UWSNs, categorize both MAC and routing protocols with a new taxonomy, as well as provide a comparative discussion. Finally, we conclude by presenting various current problems and research difficulties for future research.
... In order to overcome this issue as well as to improve the link stability and quality, broadcast nature cooperative communication is superior. Decode & forward, estimate & forward, and amplify & forward are three cooperative techniques with capacity of channel were analyzed [3][4][5]. Underwater acoustic communications performance is challenging to meet the requirements of practical applications due to intrinsic instant-split-incidence fluctuation, low bandwidth, greater sound, and many way as well as extensive broadcast latency. ...
Underwater Acoustic Sensor Networks (UASNs) encompass concerned a great deal interest in together with the educational as well as manufacturing fields. Because of the instant predictability, incidence selectivity and extremely in complete obtainable bandwidth, the Underwater Acoustic (UWA) strait are usually recognized because it demanding message intermediate utilized nowadays. The paper proposed Cluster-Based Cuckoo Search Algorithm (CSA) to accomplish the weight of extensive underwater sensor networks. The network optimized structural design and it establishes the idea of cluster within wireless cellular message. Then, the Fuzzy Clustering Means (FCM) is used to cluster the underwater sensor nodes thereby providing information communication topology amongst underwater sensor nodes thus the whole power utilization method is able to decreased along with trouble of power utilizing stability of underwater sensor nodes be able to resolve wherever the information gathered through every cluster head is broadcast toward the bottom getting terminal equipment, with more over stability as well as consume the energy of the network. The result revealed that our proposed performance execute better results than existing optimization algorithms like GWO with GA intended for energy consumption along within formation delivery ratio, because Cluster-Based CSA is able to provide extensively less empower utilization of network thereby developing better data transmission of nodes.
... Since relay selection seriously affected network performance, the limitation needed to be further overcome. Ahmad [22] proposed a cooperative energy-saving routing (Co-EEUWSN), which optimized the physical layer transmission power and network layer links. It improved the data delivery ratio but introduced noise. ...
Underwater wireless sensor network (UWSN) is one of the effective methods to acquire ocean observation data, and research on underwater routing technology has become a hot spot. However, the lifetime of UWSN is an important factor affecting the overall performance of routing protocols. Due to the uncertain underwater environment and poor link quality, it will affect data integrity and network survival ability. Cooperative communication is an excellent technique for solving such problems. In this communication, the source node forwards data through a cooperative path to improve network throughput, while the destination node receives data packets that do not contain obvious errors. Therefore, this paper provides a cooperative communication method to solve the packet loss problem and lifetime of UWSN. The underwater-layered routing network structure is adopted to divide the network nodes into clusters for energy balance. Compared with the traditional layered protocol, the cooperative communication can better guarantee the link quality of the underwater channel. The k-means algorithm is also used to cluster nodes, and conditional probability can select cluster heads. During data transmission, relay nodes will amplify the signal and backup the data packets to avoid dropping packets. The proposed protocol is simulated and compared with non-cooperative protocols (LDBR and MLCEE), the results show that the proposed protocol outperformed the other protocols in terms of network lifetime, throughput, energy consumption and end-to-end delay.
... In noncooperative algorithms, delivery through a single link consumes less energy and time than cooperative techniques. However, these algorithms are not reliable and have greater chances of packets loss [12]. A small obstacle may lead to data loss and failure. ...
Designing an efficient, reliable, and stable algorithm for underwater acoustic wireless sensor networks (UA-WSNs) needs immense attention. It is due to their notable and distinctive challenges. To address the difficulties and challenges, the article introduces two algorithms: the multilayer sink (MuLSi) algorithm and its reliable version MuLSi-Co using the cooperation technique. The first algorithm proposes a multilayered network structure instead of a solid single structure and sinks placement at the optimal position, which reduces multiple hops communication. Moreover, the best forwarder selection amongst the nodes based on nodes’ closeness to the sink is a good choice. As a result, it makes the network perform better. Unlike the traditional algorithms, the proposed scheme does not need location information about nodes. However, the MuLSi algorithm does not fulfill the requirement of reliable operation due to a single link. Therefore, the MuLSi-Co algorithm utilizes nodes’collaborative behavior for reliable information. In cooperation, the receiver has multiple copies of the same data. Then, it combines these packets for the purpose of correct data reception. The data forwarding by the relay without any latency eliminates the synchronization problem. Moreover, the overhearing of the data gets rid of duplicate transmissions. The proposed schemes are superior in energy cost and reliable exchanging of data and have more alive and less dead nodes.
... Cooperative energy-efficient routing for UWSNs (Co-EEUWSN) was proposed [43]. The relay node is selected from the source to the destination based on the signal-to-noise ratio (SNR) and channel capacity. ...
Underwater wireless sensor networks (UWSNs) have become highly efficient in conducting various operations in maritime environments. Compared to terrestrial wireless sensor networks, routing protocols in UWSNs are prone to high propagation delay, high energy consumption, low bandwidth, and low throughput. UWSNs are remotely located and operate without the need for human intervention. Most sensor batteries are energy restricted and very difficult to replace. One of the major challenges of UWSNs is the uneven utilization of energy resources, which reduces the network lifetime. Therefore, an energy-efficient routing mechanism is necessary to overcome the aforementioned problems. Many significant studies have attempted to realize this goal by designing energy-efficient routing protocols to provide efficient packet routing from source to destination. In this paper, we focus on discussing various energy-efficient routing protocols that are currently available for UWSNs, categorize them with a new taxonomy, and provide a comparative discussion. Finally, we present various research problems that remain open and challenges for future research.
... Geological processes in ocean level, studying the water specifications that includes temperature, salinity, oxygen, bacteria and its pollution levels, Mines discovery, weather changes forecast, studying the humankind influence on the marine ecosystems, discovering the underwater oil fields are some examples of these motivations [1][2][3][4][5]. ...
The provision of proper routing methods in wireless sensor networks is important due to the sensors' limited hardware and software resources. Some important metrics should be achieved with the use of an efficient routing algorithm, such as low packet loss, improved quality of service, and low energy consumption. Clustering-based routing algorithms have a more efficient performance in the case of link breakages, compared to the other table-based methods. Therefore, a new clustering-based routing algorithm is proposed in this paper that takes the sensors' energy limitation into consideration. The proposed method is designed based on a three-step fuzzy logic. The steps are used to determine the cluster head node and to discover and select a suitable route. In the proposed fuzzy system, the best selection is done based on the existing real-time information. Simulation results show that the proposed method results in a 7% reduction in the network energy consumption simultaneous with a higher packet delivery ratio up to 4% in comparison with IDACB, as the basic algorithm.
... For larger organizations, a known approach to utilize energy but is costly during implementation is the use of underwater based cooling systems, similar to what was presented at the work of Ahmad et. al (Ahmad, 2017). ...
... In [15], cooperative communication is exploited to develop a routing algorithm with efficient energy for UWSNs. One omnidirectional antenna is implemented in each node, and the merits of spatial diversity are taken into consideration to coordinate the multiple nodes. ...
In today's scenario, underwater wireless sensor network (UWSN) has raised as a most famous research areas for the researchers due to its advancement in the real world. In UWSNs, the sensor nodes sense the environment, and then this sensed information is conveyed to one of the sink node and finally to the base station for processing. It is a known fact that nearly about 70% of the total earth surface is filled with the water. It is difficult for the humans to get the valuable information from the seabed. Major applications of UWSN are marine surveillance, sea monitoring, deep sea archaeology, oil monitoring etc. Major goal of this work is to provide the broad survey of underwater sensor networks with its application, deployment techniques and routing algorithms. This study also provides a comparative analysis of the deployment techniques and routing algorithms that will aid the researchers to find the research gaps in the deployment and routing techniques. Moreover, some of the UWSN applications also reviewed, which provides varied and valuable information about the UWSN approach. This study presents an overview about the conventional technologies of UWSN and its major focus is to present the significant research approaches towards the UWSNs' applications, deployment techniques, and routing process.
... The harsh and unpredictable nature of the sea is one of the major hurdles to reliable communications in underwater wireless sensor networks (UWSNs). The usually variable characteristics of the sea, therefore, need to be properly addressed so that information is reliably transmitted towards the end destination [1]. Such reliable information transmission finds applications in tactical surveillance, disaster prevention, assisted navigation, resource investigation, environmental monitoring and oil and gas spill [2][3][4][5][6]. ...
Owing to the harsh and unpredictable behavior of the sea channel, network protocols that combat the undesirable and challenging properties of the channel are of critical significance. Protocols addressing such challenges exist in literature. However, these protocols consume an excessive amount of energy due to redundant packets transmission or have computational complexity by being dependent on the geographical positions of nodes. To address these challenges, this article designs two protocols for underwater wireless sensor networks (UWSNs). The first protocol, depth and noise-aware routing (DNAR), incorporates the extent of link noise in combination with the depth of a node to decide the next information forwarding candidate. However, it sends data over a single link and is, therefore, vulnerable to the harshness of the channel. Therefore, routing in a cooperative fashion is added to it that makes another scheme called cooperative DNAR (Co-DNAR), which uses source-relay-destination triplets in information advancement. This reduces the probability of information corruption that would otherwise be sent over a single source-destination link. Simulations-backed results reveal the superior performance of the proposed schemes over some competitive schemes in consumed energy, packet advancement to destination, and network stability.
... The designing of routing protocols is not an easy task in underwater wireless sensor network due to acoustic channel limitations, propagation delay, low battery power, water pressure and water current [4][5][6]. The underwater obstacles, water pressure and water current affects the link quality of the for routing path [7,8] due the node mobility. This research paper focuses the link-aware routing protocols with its advantages, limitations and metric performance analysis. ...
Underwater Wireless Sensor Network becomes more attractive area for researchers due to its well-known applications like: oil/gas, silver, gold, minerals, ocean monitoring, pollution monitoring, tactical surveillance etc. The researchers are mining the application based information from underwater through designing of routing protocols. The designing of the link-aware routing protocols is one of the challenging tasks due to underwater obstacles like: acoustic channel limitations, propagation delay, water pressure, water current which effects the node movement and node may drop the packets. This research article focuses the link-aware routing protocols with their limitations and drawbacks. The performance analysis through analytical method focuses the unique parameters through which we can examine which protocol is controls the link quality in underwater environment.
... However, it is a harsh environment that makes the delivery of packets from the bottom to the surface of water a challenging task. Cooperative routing is considered as one of the best solutions to reliably delivery packets to the water surface [2]. It is similar to the concept of sparse recovery in that a destination node combines two noisy copies of the same data packets, one from the source and one from the relay node. ...
Cooperative routing mitigates the adverse channel effects in the harsh underwater environment
and ensures reliable delivery of packets from the bottom to the surface of water. Cooperative routing is
analogous to sparse recovery in that faded copies of data packets are processed by the destination node to
extract the desired information. However, it usually requires information about the two or three position
coordinates of the nodes. It also requires the synchronization of the source, relay, and destination nodes.
These features make the cooperative routing a challenging task as sensor nodes move with water currents.
Moreover, the data packets are simply discarded if the acceptable threshold is not met at the destination.
This threatens the reliable delivery of data to the final destination. To cope with these challenges, this
paper proposes a cooperative energy-efficient optimal relay selection protocol for underwater wireless
sensor networks. Unlike the existing routing protocols involving cooperation, the proposed scheme combines
location and depth of the sensor nodes to select the destination nodes. Combination of these two parameters
does not involve knowing the position coordinates of the nodes and results in selection of the destination
nodes closest to the water surface. As a result, data packets are less affected by the channel properties.
In addition, a source node chooses a relay node and a destination node. Data packets are sent to the destination
node by the relay node as soon as the relay node receives them. This eliminates the need for synchronization
among the source, relay, and destination nodes. Moreover, the destination node acknowledges the source
node about the successful reception or retransmission of the data packets. This overcomes the packets drop.
Based on simulation results, the proposed scheme is superior in delivering packets to the final destination
than some existing techniques.
... Stable election protocol (SEP) and prolong stable election protocol (P-SEP) are proposed to balance the energy consumption in WSNs [8] and to increase the network stability [9]. Energy efficiency of acoustic UWSNs has been recently investigated in [10] for amplify-and-forward scheme along with a minimum energy routing protocol. An enhanced energy efficient protocol is addressed in [11], which also takes the depth of sensor nodes into account. ...
Underwater wireless technologies demand to transmit at higher data rate for ocean exploration. Currently, large coverage is achieved by acoustic sensor networks with low data rate, high cost, high latency, high power consumption, and negative impact on marine mammals. Meanwhile, optical communication for underwater networks has the advantage of the higher data rate albeit for limited communication distances. Moreover, energy consumption is another major problem for underwater sensor networks, due to limited battery power and difficulty in replacing or recharging the battery of a sensor node. The ultimate solution to this problem is to add energy harvesting capability to the acoustic-optical sensor nodes. Localization of underwater sensor networks is of utmost importance because the data collected from underwater sensor nodes is useful only if the location of the nodes is known. Therefore, a novel localization technique for energy harvesting hybrid acoustic-optical underwater wireless sensor networks (AO-UWSNs) is proposed. AO-UWSN employs optical communication for higher data rate at a short transmission distance and employs acoustic communication for low data rate and long transmission distance. A hybrid received signal strength (RSS) based localization technique is proposed to localize the nodes in AO-UWSNs. The proposed technique combines the noisy RSS based measurements from acoustic communication and optical communication and estimates the final locations of acoustic-optical sensor nodes. A weighted multiple observations paradigm is proposed for hybrid estimated distances to suppress the noisy observations and give more importance to the accurate observations. Furthermore, the closed form solution for Cramer-Rao lower bound (CRLB) is derived for localization accuracy of the proposed technique.
... SACRP shows significant improvement in terms of delay and PDR. A routing protocol called on energy efficiency in UWSNs with cooperative routing [51] has been proposed to achieve energy conservation in the network. In this scheme, AF technique is used at the relay node for amplification of signals and fixed ratio combining (FRC) is incorporated at receiver node as a cooperative combining technique to combine the received signals. ...
In this work, we present two routing protocols for circular underwater wireless sensor networks (UWSNs); circular sparsity-aware energy efficient clustering (CSEEC) and circular depth-based sparsity-aware energy efficient clustering (CDSEEC) with sink mobility. In CSEEC, we divide circular network area into 5 concentric circular regions. We deployed sensor nodes randomly and placed a static sink at the top of the circular underwater network region. We further sub-divided the 5 concentric circles into 10 regions. Then, we identified sparse and dense regions based on the number of nodes in each region. We used cluster based routing approach in dense network regions and introduced sink mobility in least node density region to achieve balanced energy consumption in the network. In CDSEEC, circular network area is divided into upper and lower semi-circles. Sensor nodes are random uniformly deployed in upper and lower semi-circles and a static sink is placed at the surface of the network region. In upper semi-circle, each sensor node send its sensed data to surface sink using depth information of sensor nodes to achieve energy efficiency by selecting forwarder node with minimum depth. In lower semi-circle, we implement cluster based routing approach in high node density regions and used sink mobility in least density network regions to achieve balanced energy consumption. In UWSNs, uneven distribution of sensor nodes and dynamic network topology creates void holes and high collision probability due to channel interference in dense networks. For avoiding void holes and reducing collision probability, we proposed a virtual chain based routing (VCBR) protocol for UWSNs. In VCBR, we build virtual chains between sensor nodes and sinks to avoid void holes. VCBR also minimizes collision probability which is due to channel interference in the network. The proposed VCBR protocol, introduces a mechanism to forward data packet through best suitable virtual chain to manage the energy resources of sensor nodes efficiently during data communication. The shortest virtual chain between source node and destination is calculated based on the location information of sensor nodes. Furthermore, we also exploit cooperative diversity by presenting two routing protocols (i.e., fixed adaptive cooperative virtual chain based routing (FACVCBR) and incremental adaptive cooperative virtual chain based routing (IACVCBR) to achieve data reliability and prolong network lifetime. In FACVCBR, source node broadcasts data to destination and two relays to achieve diversity which results in data reliability. In IACVCBR, retransmission of data packet is done incrementally to improve data reliability and successful delivery of data packets. In proposed FACVCBR and IACVCBR protocols, we introduce adaptive power control mechanism to utilize energy of sensor nodes in an efficient manner. We validate our propositions via simulations. The results verify that our proposed routing protocols outperform baseline protocols in terms of selected performance parameters.
Because of its wide application in the underwater environment, underwater acoustic networks (UANs) have received high attention. However, the intrinsic attributions of low bandwidth, long propagation delay, high bit error rate, and restricted energy bring about great challenges to data transmission in UANs. In this paper, we propose a routing protocol for UANs called fuzzy control-based layering routing protocol (FCLR). With the FCLR protocol, an underwater node may learn or update its layer and the information of its neighbors from packets overhead before selecting the best forwarding node. A fuzzy control system is used to select the best forwarding node based on input variables including residual energy and node density of neighbor nodes. Extensive experiments are conducted by the NS3 network simulator to evaluate the performance of the FCLR protocol. The results show that the FCLR protocol has superior performance in terms of packet delivery rate, end to end delay, and total energy consumption. Furthermore, the FCLR protocol is tested in Qinghai Lake, the largest saltwater lake in China, and its performance was evaluated in terms of packet delivery rate, throughput, and end-to-end delay. When nodes are moving, the packet delivery rate can reach 92.6 percent and the throughput can reach 350.64bps.
Several data forwarding and clustering techniques have been proposed to improve Underwater Wireless Sensor Networks (UWSNs) performance, but void communications, packet collisions, and energy efficiency remain unresolved. We introduce a novel routing solution for energy and QoS-efficient data transmission from the underwater sensor node to the surface sink using Swarm Intelligence (SI). The protocol Energy Optimization using the Routing Optimization (EORO) is proposed to overcome the existing challenges. We design Effective Fitness Function-based Particle Swarm Optimization (EFF-PSO) to choose the optimal forwarder node for UWSN data delivery. In EORO, forwarding relay nodes are discovered by the intended source node using location information first. Then EFF-PSO algorithm is applied to select the optimal relay node considering the rich set of parameters. Four parameters of each forwarder node are used for fitness computation as residual energy, packet transmission ability, node connectivity, and distance. These parameters are deliberately chosen to reduce energy consumption, latency, and throughput by avoiding packet collisions. EORO surpassed underlying routing solutions in throughput, energy consumption, latency, and Packet Delivery Ratio (PDR).
Cancer is one of the leading causes of death. According to World Health Organization, lung cancer is the most common cause of cancer deaths in 2020, with over 1.8 million deaths. Therefore, lung cancer mortality can be reduced with early detection and treatment. The components of early detection require screening and accurate detection of the tumor for staging and treatment planning. Due to the advances in medicine, nuclear medicine has become the forefront of precise lung cancer diagnosis. Currently, PET/CT is the most preferred diagnostic modality for lung cancer detection. However, variable results and noise in the imaging modalities and the lung's complexity as an organ have made it challenging to identify lung tumors from the clinical images. In addition, the factors such as respiration can cause blurry images and introduce other artifacts in the images. Although nuclear medicine is at the forefront of diagnosing, evaluating, and treating various diseases, it is highly dependent on image quality, which has led to many approaches, such as the fusion of modalities to evaluate the disease. In addition, the fusion of diagnostic modalities can be accurate when well-processed images are acquired, which is challenging due to different diagnostic machines and external and internal factors associated with lung cancer patients. The current works focus on single imaging modalities for lung cancer detection, and there are no specific techniques identified individually for PET and CT images, respectively, for attaining effective and noise-free hybrid imaging for lung cancer detection. Based on the survey, it has been identified that several image preprocessing filters are used for different noise types. However, for successful preprocessing, it is essential to identify the types of noise present in PET and CT images and the appropriate techniques that perform well for these modalities. Therefore, the primary aim of the review is to identify efficient preprocessing techniques for noise and artifact removal in the PET/CT images that can preserve the critical features of the tumor for accurate lung cancer diagnosis.
A wireless sensor network incorporates a range of sensor motes or nodes that normally run-on battery power with limited energy capacity and also the battery replacement is a difficult job because of the size of these networks. Energy efficiency is thus one of the main problem and the design of energy-efficient protocols is essential for life extension. In this paper, we discuss communication systems that may have a major effect on the total dissipation of energy of the WSN networks. Based on the reviews, that traditional mechanisms for route discovery, static clustering, multi-hop routing as well as minimum transmission are not ideal for heterogeneous sensor network operations, we formulated customized low-energy network clustering hierarchy (CLENCH) which uses the random rotational mode of local cluster sink stations (cluster heads) for dynamic distribution of energy between the sensor nodes within the network. Simulation showed that CLENCH may reduce power consumption by as much as eight factors compared to traditional routing methods. CLENCH may also uniformly distribute energy among the sensor nodes which almost doubles the usable network lifetime for the model designed.
Wireless data transmission on the Internet of Things (IoT) needs data-aware communication protocols. Clustering is one of the effective network management approaches that enhance the lifetime of IoT. The primary challenge in the data transmission across IoT is designing an energy-efficient clustering mechanism. Existing protocols struggle with the non-optimal selection of CHs and frequent re-clustering on IoT, which leads to significant energy consumption. If the cluster head (CH) lifetime of the devices (nodes) is known prior, then re-clustering can be avoided to a reasonable extent. Therefore, in this paper, we estimate the lifetime of devices as CHs by solving a linear optimization problem to extend the first node death as much as possible and also, stalls the frequent re-clustering process to minimize the energy consumption. We also apply the uniform distribution of CHs to ensure balanced energy consumption on IoT devices. The proposed clustering technique named ECFEL (Efficient Clustering using Fuzzy logic based on Estimated Lifetime) for IoT outperforms the existing protocols, namely Low Energy Adaptive Clustering Hierarchy (LEACH), MODified LEACH (MOD-LEACH), Dynamic k-LEACH (DkLEACH), Novel-PSO-LEACH, FM-SCHEL, and M-IWOCA techniques in terms of first node death (FND), half node death (HND), last node death (LND). Our simulation results showcase that ECFEL is having a better lifetime in terms of FND, HND, and LND, respectively. Furthermore, the experiments also confirm that ECFEL consumes less energy while maintaining a packet delivery ratio for a more extended period.
Underwater acoustic sensor networks (UASN) play a crucial role in various applications such as tsunami detection, surveillance of the ocean by the defense department, monitoring offshore oil, and identifying gas basins underwater. UASNs can be one of the supporting infrastructures for the Internet of Things (IoT). UASNs have the problems of long latency, high bit error rate, and low bandwidth. These pose various challenges such as high consumption of energy, low reliability, low packet retransmission, and high delay for UASNs. To overcome the shortcomings mentioned above, various approaches are suggested. This article proposes a multi-layer fuzzy logic cluster-based energy-efficient routing protocol for UASNs. It splits the network area into equal sized rings. The priority number (PRN) is utilized for all underwater cluster heads (UCHs). Based on the highest PRN, the UCH starts communicating among UCHs. Here, the PRN makes the task very selective avoiding collisions and also reducing propagation delays. The cluster formation is done by sending a message to all underwater cluster members (UCMs) and the selection of UCH and UCM are done. Each has a threshold value. The intra-ring clustering process splits a ring into equal-sized clusters. Additionally, inter-cluster routing applies the fuzzy logic metrics to choose the optimum data route in transferring the data from the underwater cluster head (UCH) to the sink node (SN). It is tested using Aqua-Sim simulation which is based on NS2. It is compared with an existing protocol such as multi-layer cluster energy efficient (MLCEE), depth-based routing (DBR), energy efficient DBR (EEDBR). The results prove that it has improved energy efficiency, packet delivery ratio, throughput, and the network's lifetime.
Underwater Wireless Sensor Networks (UWSNs) consist of several sensor nodes deployed underwater and gathering information from the underwater situation. Sometimes during a communication void regions occur when a forwarder node is unable to find the next forwarder node closer to the sink within the transmission ranges which results from its took extra energy consumption. In this research work, we intend schemes for void hole avoidance. First one is, Avoiding Void Hole Adaptive Hop by Hop Vector‐Based Forwarding (AVH‐AHH‐VBF) in an UWSN, and the second, scheme for increasing lifetime and minimizing consumption of energy of the network, Sink Mobility (SM‐AHH‐VBF). Simulation results show that our schemes outperform compared with baseline solution in terms of average Packet Delivery Ratio (PDR), Average Propagation Distance (APD), energy consumption. The simulation results verify the AVH‐AHH‐VBF scheme results is equals to 14% and SM/AHH‐VBF equal to 32% in terms of PDR, AVH‐AHH‐VBF equals to 57% and SM equals to 39% for energy consumption, AVH‐AHH‐VBF had a tradeoff of 63% because of considering two hops and SM equals 20% tradeoff for the average delay and AVH‐AHH‐VBF equals 35% and SM equals 61% improvement for average APD.
In this thesis, a suite of schemes is presented to enhance the performance of cooperative communication networks. In particular, techniques to improve the outage probability, end-to-end delay and throughput performances are presented. Firstly, a buffer-aided cooperative communication is studied and analyzed for packet selection and relay selection. A three-node network is considered in the beginning and the phenomenon of packet diversity is taken into consideration to overcome bad channel conditions of the
source to relay (SR) and relay to destination (RD) links. The closed-form expressions for the computation of the outage probability along with the delay, throughput and diversity gain are derived. Then, packet selection is studied along with relay selection for buffer-aided amplify and forward (AF) cooperative relaying networks. The proposed protocol is analyzed for both symmetric and asymmetric channel conditions and buffer size using multiple antennas at relays and compared against the existing buffer-aided schemes.
Markov chain (MC) is used to derive the closed-form expressions for outage probability, diversity gain, delay and throughput.
Next, the performance of SNR based hybrid decode-amplify-forward relaying protocol is observed. When SR link is the strongest, data is transmitted to the selected relay and checked against the predefined threshold at the relay. If it is greater than the threshold, data is decoded and stored in the corresponding buffer. Otherwise, it is amplified and stored in the respective buffer. When RD link is the strongest, data is transmitted to the destination. MC based theoretical framework is used to derive an expression for the outage probability, the average end-to-end delay and throughput. Then, relay selection schemes considering the instantaneous link quality along with buffer status in the relay selection are proposed. A scheme is proposed that simultaneously considers buffer status and link quality. Then, we discuss multiple links with equal weights using a general relay selection factor. It includes the weight of the link as the first metric and the link quality, or priority, as the second metric for different cases of the same weight. The proposed scheme is evaluated for symmetric and asymmetric channel conditions.
Moreover, we propose a specific parameter, termed as the bu�er-limit, which controls the selection of SR or RD links and also have its impact on the average delay and throughput. In this scheme, the outage probability is traded with the average end-to-end queuing delay or the average throughput by adjusting the values of the buffer-limit. The MC based framework is employed to derive the closed-form expressions for the outage probability, average end-to-end queuing delay and the average throughput. The suggested schemes are compared to the existing bufferaided relay selection schemes.
Lastly, we consider the energy constraint cooperative network and propose a generalized approach to study the performance of energy harvesting relaying schemes.
The unified modeling of generalized energy harvesting relaying (GEHR) scheme covers the non-energy harvesting schemes and the well-known energy harvesting schemes, i.e., time switching based relaying (TSR) and power splitting based relaying (PSR). Moreover, the scheme also caters the hybrid of both TSR and PSR schemes. The closed-form expressions for the outage probability and ergodic capacity and average throughput are formulated for non-mixed Rayleigh fading and mixed Rayleigh-Rician fading channels. Each case is analyzed for AF and decode and forward relaying models. Comprehensive Monte-Carlo simulations confirm all theoretical results.
Underwater sensor networks are ad hoc networks to monitor different underwater phenomenons such as pollution control, petrol mining, and observation of echo life. For underwater sensor networks to operate for longer duration of time, hoarding energy from background sources is viable option. One such source is harvesting energy from water currents using piezoelectric material embedded in sensor nodes. Piezoelectric materials can produce electricity when pressure is applied on it in the form of oscillating frequency produced by hydrophones. In this paper we have analyzed cooperation-based technique in underwater sensor networks containing sensor nodes which select relay nodes in their immediate vicinity with energy harvesting capabilities. These relay sensor nodes employ technique of amplify and forward (AF). As in current literature, all cooperative-based UWSN routing techniques are without integration of any type of energy harvesting schemes; considering this, we have incorporated piezoelectric energy harvesting mechanism into relay nodes in order to decrease end-to-end delay, increase stability period, and improve packet delivery ratio. As case study, we have selected cooperation-based UWSN protocol ARCUN (Analytical Approach towards Reliability with Cooperation for Underwater WSNs) and integrated piezoelectric energy harvesting scheme with it. We compared our new scheme EH (energy harvested)-ARCUN with ARCUN and RACE (Reliability and Adaptive Cooperation for Efficient Underwater Sensor Networks). Simulation results show improvement of EH-ARCUN over ARCUN and RACE schemes.
Mitigation of channel unfavorable circumstances during data routing in underwater wireless sensor networks (UWSNs) has utmost significance. It guarantees saving packet corruption along unfavorable channels so that vital data is not lost or become meaningless. This paper proposes two routing protocols for UWSNs: localization free energy efficient routing (LFEER) and its improved version, localization free energy efficient cooperative routing (Co-LFEER). The LFEER makes decision of choosing a relay based on its maximum residual energy, number of hops and the bit error rate of the link over which packets are transmitted. These metrics are chosen to save packets from corruption to the maximum limit and maintain stable paths (where nodes do not die soon). Since a single link is used in the LFEER for packets forwarding, the link may become worse with changing circumstances of the channel. To deal with this issue, cooperative routing is added to the LFFER to construct the Co-LFEER protocol, in which some copies of packets are received by destination to decide about packets quality. Converse to some prevalent protocols, both LFEER and Co-LFEER are independent of knowing the sensor nodes’ positions, which increases computational complexity and wasteful utilization of resources. Based on extensive simulations, the proposed schemes are better than Co-DBR in reducing energy utilization and advancing packets to the desired destination.
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.
This paper embeds a bi-fold contribution for Underwater Wireless Sensor Networks 1 (UWSNs); performance analysis of incremental relaying in terms of outage and error probability, 2 and based on the analysis proposition of two new cooperative routing protocols. Subject to 3 the first contribution, a three step procedure is carried out; a system model is presented, the 4 number of available relays are determined, and based on cooperative incremental retransmission 5 methodology, closed-form expressions for outage and error probability are derived. Subject to the 6 second contribution, Adaptive Cooperation in Energy (ACE) efficient depth based routing and 7 Enhanced-ACE (E-ACE) are presented. In the proposed model, feedback mechanism indicates 8 success or failure of data transmission. If direct transmission is successful, there is no need of 9 relaying by cooperative relay nodes. In case of failure, all the available relays retransmit the data 10 one by one till the desired signal quality is achieved at destination. Simulation results show that the 11 ACE and E-ACE significantly improves network performance, i.e., throughput, when compared 12 with other incremental relaying protocols like Cooperative Automatic Repeat reQuest (CARQ). 13 E-ACE and ACE achieve 69% and 63% more throughput respectively as compared to CARQ in 14 hard underwater environment. 15 Keywords: Underwater wireless sensor network, incremental relaying, cooperative diversity, 16 retransmission, automatic repeat request.
Underwater Wireless Sensor Network (UWSN) communication at high frequencies is extremely challenging. The intricacies presented by the underwater environment are far more compared to the terrestrial environment. The prime reason for such intricacies are the physical characteristics of the underwater environment that have a big impact on electromagnetic (EM) signals. Acoustics signals are by far the most preferred choice for underwater wireless communication. Because high frequency signals have the luxury of large bandwidth (BW) at shorter distances, high frequency EM signals cannot penetrate and propagate deep in underwater environments. The EM properties of water tend to resist their propagation and cause severe attenuation. Accordingly, there are two questions that need to be addressed for underwater environment, first what happens when high frequency EM signals operating at 2.4 GHz are used for communication, and second which factors affect the most to high frequency EM signals. To answer these questions, we present real-time experiments conducted at 2.4 GHz in terrestrial and underwater (fresh water) environments. The obtained results helped in studying the physical characteristics (i.e., EM properties, propagation and absorption loss) of underwater environments. It is observed that high frequency EM signals can propagate in fresh water at a shallow depth only and can be considered for a specific class of applications such as water sports. Furthermore, path loss, velocity of propagation, absorption loss and the rate of signal loss in different underwater environments are also calculated and presented in order to understand why EM signals cannot propagate in sea water and oceanic water environments. An optimal solk6ution for underwater communication in terms of coverage distance, bandwidth and nature of communication is presented, along with possible underwater applications of UWSNs at 2.4 GHz.
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.
The area of three-dimensional (3D) underwater wireless sensor networks (UWSNs) has attracted significant attention recently due to its applications in detecting and observing phenomena that cannot be adequately observed by means of two-dimensional UWSNs. However, designing routing protocols for 3D UWSNs is a challenging task due to stringent constraints imposed by acoustic communications and high energy consumption in acoustic modems. In this paper, we present an ultrasonic frog calling algorithm (UFCA) that aims to achieve energy-efficient routing under harsh underwater conditions of UWSNs. In UFCA, the process of selecting relay nodes to forward the data packet is similar to that of calling behavior of ultrasonic frog for mating. We define the gravity function to represent the attractiveness from one sensor node to another. In order to save energy, different sensor nodes adopt different transmission radius and the values can be tuned dynamically according to their residual energy. Moreover, the sensor nodes that own less energy or locate in worse places choose to enter sleep mode for the purpose of saving energy. Simulation results show the performance improvement in metrics of packet delivery ratio, energy consumption, throughput, and end-to-end delay as compared to existing state-of-the-art routing protocols.
There are many applications for using wireless sensor networks (WSN) in ocean science; however, identifying the exact location of a sensor by itself (localization) is still a challenging problem, where global positioning system (GPS) devices are not applicable underwater. Precise distance measurement between two sensors is a tool of localization and received signal strength (RSS), reflecting transmission loss (TL) phenomena, is widely used in terrestrial WSNs for that matter. Underwater acoustic sensor networks have not been used (UASN), due to the complexity of the TL function. In this paper, we addressed these problems by expressing underwater TL via the Lambert W function, for accurate distance inversion by the Halley method, and compared this to Newton-Raphson inversion. Mathematical proof, MATLAB simulation, and real device implementation demonstrate the accuracy and efficiency of the proposed equation in distance calculation, with fewer iterations, computation stability for short and long distances, and remarkably short processing time. Then, the sensitivities of Lambert W function and Newton-Raphson inversion to alteration in TL were examined. The simulation results showed that Lambert W function is more stable to errors than Newton-Raphson inversion. Finally, with a likelihood method, it was shown that RSS is a practical tool for distance measurement in UASN.
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.
Due to intrinsic properties of aqueous environments, routing protocols for underwater wireless sensor network (UWSN) have to cope with many challenges such as long propagation delay, bad robustness, and high energy consumption. Basic ant colony optimization algorithm (ACOA) is an intelligent heuristic algorithm which has good robustness, distributed computing and combines with other algorithms easily. But its disadvantage is that it may converge at local solution, not global solution. Artificial fish swarm algorithm (AFSA) is one kind of intelligent algorithm that can converge at global solution set quickly but has lower precision in finding global solution. Therefore we can make use of AFSA and ACOA based on idea of complementary advantages. So ACOA-AFSA fusion routing algorithm is proposed which possesses advantages of AFSA and ACOA. As fusion algorithm has aforementioned virtues, it can reduce existing routing protocols’ transmission delay, energy consumption and improve routing protocols’ robustness theoretically. Finally we verify the feasibility and effectiveness of fusion algorithm through a series of simulations.
Tracking underwater targets is a focused application area in modern underwater defence systems. Using traditional techniques based on imaging or sensor arrays may be difficult and impractical in some mission-critical systems. Alternatively, the underwater wireless sensor network (UWSN) is able to offer a promising solution. This paper tackles the problem of accurately tracking underwater targets moving through the UWSN environment. This problem is considered nonlinear and non-Gaussian where the present solution methods based on the particle filter technique are powerful and simple to implement. For three-dimensional underwater maneuvering target tracking, the traditional particle filter tracking algorithm may fail to track the targets robustly and accurately. Thus, the interacting multiple model method is combined with the particle filter to cope with uncertainties in target maneuvers. Simulation results show that the proposed method is a promising substitute for the traditional imaging-based or sensor-based approaches.
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.
This is the second in a two-part series of papers on information-theoretic capacity scaling laws for an underwater acoustic network. Part II focuses on a dense network scenario, where nodes are deployed in a unit area. By deriving a cut-set upper bound on the capacity scaling, we first show that there exists either a bandwidth or power limitation, or both, according to the operating regimes (i.e., path-loss attenuation regimes), thus yielding the upper bound that follows three fundamentally different information transfer arguments. In addition, an achievability result based on the multi-hop (MH) transmission is presented for dense networks. MH is shown to guarantee the order optimality under certain operating regimes. More specifically, it turns out that scaling the carrier frequency faster than or as
$n^{1/4}$
is instrumental towards achieving the order optimality of the MH protocol.
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.
Wireless sensor networks (WSN) are presented as
proper solution for wildfire monitoring. However, this application
requires a design of WSN taking into account the network lifetime
and the shadowing effect generated by the trees in the forest
environment. Cooperative communication is a promising solution
for WSN which uses, at each hop, the resources of multiple nodes
to transmit its data. Thus, by sharing resources between nodes,
the transmission quality is enhanced. In this paper, we use the
technique of reinforcement learning by opponent modeling, optimizing
a cooperative communication protocol based on RSSI and
node energy consumption in a competitive context (RSSI/energy-CC), that is, an energy and quality-of-service aware-based cooperative
communication routing protocol. Simulation results show that the
proposed algorithm performs well in terms of network lifetime,
packet delay, and energy consumption.
The remotely powered underwater acoustic sensor
networks (RPUASN) paradigm is introduced, whereby sensor
nodes harvest and store the power supplied by an external
acoustic source, indefinitely extending their lifetime. Necessary
source characteristics are determined. Feasibility is illustrated
with realistic examples, and open research issues are pointed
out. Performance of RPUASN is directly related to the sensing
coverage and communication connectivity over the field the
sensor nodes are deployed. The required number of RPUASN
nodes and the volume which is guaranteed to be covered by the
nodes are analyzed in terms of electrical power, range, directivity,
and transmission frequency of the external acoustic source, and
node power requirements.
In this paper, we propose an output-threshold multiple relay selection scheme for dual-hop multi-branch cooperative wireless networks. The proposed scheme selects the first L<sub>c</sub> arbitrary ordered relays out of L relays such that the maximal ratio combined signal-to-noise-ratio (SNR) of the L<sub>c</sub> relayed paths and the direct path barely exceeds a preset threshold. Closed-form expressions are derived for the cumulative distribution function, the probability density function, and the moment generating function of an output SNR upper bound for independent and identically distributed Rayleigh fading. Lower bounds for the outage probability, the average symbol error rate, and the average number of selected relays are also derived. Moreover, upper bounds for the average output SNR and the ergodic capacity are also derived. The analytical results are verified via the Monte-Carlo simulation. The performance of our proposed scheme is compared to that of the existing relay selection schemes. The proposed schemes provide more flexibility in utilizing bandwidth and spatial diversity in cooperative wireless networks.
In this paper, we investigate a mobicast, also called a mobile geocast, problem in three-dimensional (3-D) underwater sensor networks (USNs), which aims to overcome the hole problem and minimizes the energy consumption of the sensor nodes while maximizing the data collection. In this paper, all underwater sensor nodes are randomly distributed in a 3-D underwater environment in the sea to form a 3-D USN. Considered a mobile sink or an autonomous underwater vehicle (AUV), all possible sensor nodes near the AUV form a 3-D geographic zone called a 3-D zone of reference (3-D ZOR). The AUV travels a user-defined route and continuously collects data from sensor nodes within a series of 3-D ZORs at different times. The main problem is how to efficiently collect data from sensor nodes within a 3-D ZOR while those sensor nodes are usually in sleep mode for a long period. The routing protocol relies on two phases: the first phase consists of collecting data within a 3-D ZOR, and the second phase consists of waking up those sensor nodes in the next 3-D ZOR to be queried while trying to avoid topology holes. To save power, only sensor nodes in a 3-D ZOR are notified to enter the active mode in order to deliver sensed results to the AUV. The specific characteristics of USNs, including low communication bandwidth, large propagation delay, and ocean current, are significantly different from wireless sensor networks. To consider the characteristics of USNs, a new mobicast routing protocol is developed in 3-D USNs. The key design challenge is to develop a power-saving mobicast protocol in 3-D USNs to overcome the unpredictable 3-D hole problem. To solve the hole problem, an “apple slice” technique is used to build multiple segments to surround the hole and to assure routing path continuity. Finally, performance analysis is derived, and simulation results illustrate the performance improvement in successful delivery rate, power consumption, and message overhead.
Cooperative communication systems using various relay strategies can achieve spatial diversity gains, enhance coverage, and potentially increase capacity. For the practically attractive decode-and-forward (DF) relay strategy, we derive a high-performance low-complexity coherent demodulator at the destination in the form of a weighted combiner. The weights are selected adaptively to account for the quality of both source-relay-destination and source-destination links. Analysis proves that the novel coherent demodulator can achieve the maximum possible diversity, regardless of the underlying constellation. Its error performance tightly bounds that of maximum-likelihood (ML) demodulation, which provably quantifies the diversity gain of ML detection with DF relaying. Simulations corroborate the analysis and compare the performance of the novel decoder with existing diversity-achieving strategies including analog amplify-and-forward and selective-relaying.
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.
Underwater Acoustic Sensor Networks (UASNs) have recently been attracted significant attention from both academia and industry for resources exploration and for scientific data gathering in underwater environments. The important characteristic of a UASN is that most underwater acoustic sensor nodes have a certain beam width and a three dimension direction, which is ignored by the existing underwater routing protocols. This characteristic will reduce the network connectivity and cause a large number of asymmetric links, so it will lead to sharp decline of the existing protocol performance. We develop a routing protocol to tackle this problem in UASNs. A link detection mechanism is employed to get link state information (symmetrical link or asymmetric link), and an adaptive routing feedback method is adopted to make full use of the underwater asymmetric link and save energy. We propose a time-based priority forwarding mechanism and utilize downstream node table to prevent flooding, and a credit-based routing table update mechanism is adopted to avoid energy consumption caused by frequent update of routing table. The proposed protocol is compared with a representative routing protocol for UASNs. The simulation results verify the effectiveness and feasibility of the proposed protocol.
Many wireless sensor network applications require sensor nodes to be deployed on the ground or other surfaces. However, there has been little effort to characterize the large- and small-scale path loss for surface-level radio communications. We present a comprehensive measurement of path loss and fading characteriztics for surface-level sensor nodes in the 400 MHz band in both flat and irregular outdoor terrain in an effort to improve the understanding of surface-level sensor network communications performance and to increase the accuracy of sensor network modeling and simulation. Based on our measurement results, we characterize the spatial small-scale area fading effects as a Rician distribution with a distance-dependent K-factor. We also propose a new semi-empirical path loss model for outdoor surface-level wireless sensor networks called the Surface-Level Irregular Terrain (SLIT) model. We verify our model by comparing measurement results with predicted values obtained from high-resolution digital elevation model (DEM) data and computer simulation for the 400 MHz and 2.4 GHz band. Finally, we discuss the impact of the SLIT model and demonstrate through simulation the effects when SLIT is used as the path loss model for existing sensor network protocols.
Localization and mapping are the fundamental ability for underwater robots to carry out exploration and searching tasks autonomously. This paper presents a novel approach to localization and mapping of a school of wirelessly connected underwater robotic fish (URF). It is based on both Cooperative Localization Particle Filter (CLPF) scheme and Occupancy Grid Mapping Algorithm (OGMA). Using the probabilistic framework, the proposed CLPF has the major advantage that no prior knowledge about the kinematic model of URF is required to achieve accurate 3D localization. It works well when the number of mobile beacons is less than four, which is the minimum number for some traditional localization algorithms. The localization result of CLPF is fed into OGMA to build the environment map. The performance of the proposed algorithms is evaluated through extensive simulation experiments, and results verify the feasibility and effectiveness of the proposed strategy.
The depths of the oceans have a high potential for future industrial development and applications. Robotic autonomous systems will greatly depend on a reliable communications channel with operators and equipment either performing joint operations or on the surface. However, communications must face harsh conditions that hinder the performance. Neither electromagnetic nor optical technologies are suitable for communication because of their short range in this medium. Due to this, acoustic equipment is envisaged as the most appropriate technology, even though it suffers several negative effects such as strong attenuation at high (ultrasonic) frequencies, Doppler shifts and a time-varying multipath. In this paper, we describe the characteristics of the acoustic underwater channel and how it impacts the mechanisms at the link and network layers.
Cooperation and network coding are two powerful techniques for wireless networks. During the past few years a surge of research activity has tried to combine the best of these two philosophies to improve the performance and error correction capabilities of radio networks. This article gives an overview of the literature in the field, summarizes the main achievements and design guidelines found so far, and finally highlights the main challenges yet to be solved.
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.
We introduce and study the localization problem in large scale underwater acoustic sensor networks. Considering that depth information is typically available for underwater sensors, we transform the 3D underwater positioning problem into its two-dimensional counterpart via a projection technique. We then introduce a localization scheme specifically designed for large scale acoustic underwater sensor networks. The proposed localization scheme does not require time-synchronization in the network. This scheme relies on time-differences of arrival (TDoA) measured locally at a sensor to detect range differences from the sensor to three anchors that can mutually hear each other. We consider variations in the speed of sound and analyze the performance of the proposed scheme in terms of the number of localized nodes, location errors, and the number of reference nodes.
In this paper, we present a silent positioning scheme termed UPS for underwater acoustic sensor networks. UPS relies on the time difference of arrivals locally measured at a sensor to detect range differences from the sensor to four anchor nodes. These range differences are averaged over multiple beacon intervals before they are combined to estimate the 3-D sensor location through trilateration. UPS requires no time synchronization and provides location privacy at underwater vehicles/sensors whose locations need to be determined. To study the performance of UPS, we model the underwater acoustic channel as a modified ultrawideband Saleh-Valenzuela model: The arrival of each path cluster and the paths within each cluster follow double Poisson distributions, and the multipath channel gain follows a Rician distribution. Based on this channel model, we perform both theoretical analysis and simulation study on the position error of UPS under acoustic fading channels. The obtained results indicate that UPS is an effective scheme for underwater vehicle/sensor self-positioning.
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