Abstract—Underwater wireless communication (UWC) has
become a significant technique that is used to investigate the
underwater environment. It is also noteworthy that the collected
data from underwater has to transmit to inland data fusion
centers for further investigation and operating instructions need
to transmit from the inland center to underwater autonomous
vehicles (UAVs) to operate as per the real-time requirements.
Therefore, a hybrid terrestrial and UWC setup is required in
most of the underwater military and commercial applications
Development of an FHMA-based Underwater Acoustic Communications System for Mu...Waqas Tariq
This paper describes the design of an underwater acoustic communications system for multiple underwater vehicles, based on frequency-hopping multiple-access (FHMA) and tamed spread-spectrum communications. The system makes used of the tamed spread-spectrum method, frequency hopping, 4FSK, and a rake receiver. In order to make the system more practical, the underwater channel and the effect of the number of users on the bit error ratio (BER) are also taken into account. Since the necessary proving experiments are not easily conducted in the ocean, a platform is developed that uses the sound card of a computer, combined with a sound box and microphone, to transduce energy for acoustic communications. Simulated and experimental results indicate that this system could provide reliable underwater communications between multiple underwater vehicles.
An implementation of_partial_transmit_seWaleed Raza
In this article we research about underwater
acoustics transceivers. As Underwater acoustic transceivers
consume more power than Radio frequency transceivers.
The techniques which are being utilized in radio frequency
cannot be implemented directly in underwater acoustic
system it needs to be re investigated to design new methods.
To achieve reliable acoustic data transmission new
techniques should be achieved or the traditional
Orthogonal frequency divisional multiplexing techniques
should be revised. The power consumption also relies upon
underwater acoustic signal propagation and transmission
distances. Several underwater acoustic applications require
long-term monitoring of the sea. For the battery powered
modems, it becomes very serious problem. By designing an
Energy efficient OFDM Communication system we can
solve this problem. We study about peak to average power
ratio in an Orthogonal frequency divisional multiplexing
system by reducing the major draw-back of OFDM system.
The PAPR reduction utilized in this paper is Partial
Transmit Sequences for underwater acoustic OFDM
communication system which has lesser complexity. The
results have provided better performance in underwater
acoustic OFDM communication system.
Implementation of Optical wireless communication through underwater channelSANKETLKENDUR
This project is based on transformation of data like text, voice, audio and image through underwater using visible light. This is major application in military like navy and submarines, scientific community for underwater research, flood detection, climatic changes , oceanography and more . The cost of this budget around 15k to 17k.
Design of Underwater wireless optical/acoustic link for reduction of back-sca...theijes
Underwater communication plays a significant role in the study of climate change through ocean monitoring and associated sensor networks. It is severely limited when compared to free space communication because water is essentially opaque to electromagnetic radiation except in the visible band. Even in the visible band, light penetrates only a few hundred meters in the clearest waters and much less in turbid waters due to the presence of suspended sediment or high concentrations of marine life. Consequently, acoustic techniques are been used for underwater communication systems which is relatively mature and robust. Acoustic systems are capable of long range communication. But traditional underwater acoustic communications cannot provide high enough data rates to enable monitoring technology. Optical wireless communications, centred around blue-green wavelengths, are being used as an alternative. Here a hybrid design is being introduced using an optical/acoustic link to reduce back scattering of transmitted light.
Underwater localization and node mobility estimationIJECEIAES
In this paper, localizing a moving node in the context of underwater wireless sensor networks (UWSNs) is considered. Most existing algorithms have had designed to work with a static node in the networks. However, in practical case, the node is dynamic due to relative motion between the transmitter and receiver. The main idea is to record the time of arrival message (ToA) stamp and estimating the drift in the sampling frequency accordingly. It should be emphasized that, the channel conditions such as multipath and delay spread, and ambient noise is considered to make the system pragmatic. A joint prediction of the node mobility and speed are estimated based on the sampling frequency offset estimation. This sampling frequency offset drift is detected based on correlating an anticipated window in the orthogonal frequency division multiplexing (OFDM) of the received packet. The range and the distance of the mobile node is predicted from estimating the speed at the received packet and reused in the position estimation algorithm. The underwater acoustic channel is considered in this paper with 8 paths and maximum delay spread of 48 ms to simulate a pragmatic case. The performance is evaluated by adopting different nodes speeds in the simulation in two scenarios of expansion and compression. The results show that the proposed algorithm has a stable profile in the presence of severe channel conditions. Also, the result shows that the maximum speed that can be adopted in this algorithm is 9 km/h and the expansion case profile is more stable than the compression scenario. In addition, a comparison with a dynamic triangular algorithm (DTN) is presented in order to evaluate the proposed system.
LBRP: A RESILIENT ENERGY HARVESTING NOISE AWARE ROUTING PROTOCOL FOR UNDER WA...ijfcstjournal
Underwater detector network is one amongst the foremost difficult and fascinating analysis arenas that open the door of pleasing plenty of researchers during this field of study. In several under water based
sensor applications, nodes are square measured and through this the energy is affected. Thus, the mobility of each sensor nodes are measured through the water atmosphere from the water flow for sensor based protocol formations. Researchers have developed many routing protocols. However, those lost their charm with the time. This can be the demand of the age to supply associate degree upon energy-efficient and ascendable strong routing protocol for under water actuator networks. During this work, the authors tend to propose a customary routing protocol named level primarily based routing protocol (LBRP), reaching to offer strong, ascendable and energy economical routing. LBRP conjointly guarantees the most effective use of total energy consumption and ensures packet transmission which redirects as an additional reliability in compare to different routing protocols. In this work, the authors have used the level of forwarding node, residual energy and distance from the forwarding node to the causing node as a proof in multicasting technique comparisons. Throughout this work, the authors have got a recognition result concerning about
86.35% on the average in node multicasting performances. Simulation has been experienced each in a wheezy and quiet atmosphere which represents the endorsement of higher performance for the planned protocol.
LBRP: A RESILIENT ENERGY HARVESTING NOISE AWARE ROUTING PROTOCOL FOR UNDER WA...ijfcstjournal
Underwater detector network is one amongst the foremost difficult and fascinating analysis arenas that
open the door of pleasing plenty of researchers during this field of study. In several under water based
sensor applications, nodes are square measured and through this the energy is affected. Thus, the mobility
of each sensor nodes are measured through the water atmosphere from the water flow for sensor based
protocol formations. Researchers have developed many routing protocols. However, those lost their charm
with the time. This can be the demand of the age to supply associate degree upon energy-efficient and
ascendable strong routing protocol for under water actuator networks. During this work, the authors tend
to propose a customary routing protocol named level primarily based routing protocol (LBRP), reaching to
offer strong, ascendable and energy economical routing. LBRP conjointly guarantees the most effective use
of total energy consumption and ensures packet transmission which redirects as an additional reliability in
compare to different routing protocols. In this work, the authors have used the level of forwarding node,
residual energy and distance from the forwarding node to the causing node as a proof in multicasting
technique comparisons. Throughout this work, the authors have got a recognition result concerning about
86.35% on the average in node multicasting performances. Simulation has been experienced each in a
wheezy and quiet atmosphere which represents the endorsement of higher performance for the planned
protocol.
Development of an FHMA-based Underwater Acoustic Communications System for Mu...Waqas Tariq
This paper describes the design of an underwater acoustic communications system for multiple underwater vehicles, based on frequency-hopping multiple-access (FHMA) and tamed spread-spectrum communications. The system makes used of the tamed spread-spectrum method, frequency hopping, 4FSK, and a rake receiver. In order to make the system more practical, the underwater channel and the effect of the number of users on the bit error ratio (BER) are also taken into account. Since the necessary proving experiments are not easily conducted in the ocean, a platform is developed that uses the sound card of a computer, combined with a sound box and microphone, to transduce energy for acoustic communications. Simulated and experimental results indicate that this system could provide reliable underwater communications between multiple underwater vehicles.
An implementation of_partial_transmit_seWaleed Raza
In this article we research about underwater
acoustics transceivers. As Underwater acoustic transceivers
consume more power than Radio frequency transceivers.
The techniques which are being utilized in radio frequency
cannot be implemented directly in underwater acoustic
system it needs to be re investigated to design new methods.
To achieve reliable acoustic data transmission new
techniques should be achieved or the traditional
Orthogonal frequency divisional multiplexing techniques
should be revised. The power consumption also relies upon
underwater acoustic signal propagation and transmission
distances. Several underwater acoustic applications require
long-term monitoring of the sea. For the battery powered
modems, it becomes very serious problem. By designing an
Energy efficient OFDM Communication system we can
solve this problem. We study about peak to average power
ratio in an Orthogonal frequency divisional multiplexing
system by reducing the major draw-back of OFDM system.
The PAPR reduction utilized in this paper is Partial
Transmit Sequences for underwater acoustic OFDM
communication system which has lesser complexity. The
results have provided better performance in underwater
acoustic OFDM communication system.
Implementation of Optical wireless communication through underwater channelSANKETLKENDUR
This project is based on transformation of data like text, voice, audio and image through underwater using visible light. This is major application in military like navy and submarines, scientific community for underwater research, flood detection, climatic changes , oceanography and more . The cost of this budget around 15k to 17k.
Design of Underwater wireless optical/acoustic link for reduction of back-sca...theijes
Underwater communication plays a significant role in the study of climate change through ocean monitoring and associated sensor networks. It is severely limited when compared to free space communication because water is essentially opaque to electromagnetic radiation except in the visible band. Even in the visible band, light penetrates only a few hundred meters in the clearest waters and much less in turbid waters due to the presence of suspended sediment or high concentrations of marine life. Consequently, acoustic techniques are been used for underwater communication systems which is relatively mature and robust. Acoustic systems are capable of long range communication. But traditional underwater acoustic communications cannot provide high enough data rates to enable monitoring technology. Optical wireless communications, centred around blue-green wavelengths, are being used as an alternative. Here a hybrid design is being introduced using an optical/acoustic link to reduce back scattering of transmitted light.
Underwater localization and node mobility estimationIJECEIAES
In this paper, localizing a moving node in the context of underwater wireless sensor networks (UWSNs) is considered. Most existing algorithms have had designed to work with a static node in the networks. However, in practical case, the node is dynamic due to relative motion between the transmitter and receiver. The main idea is to record the time of arrival message (ToA) stamp and estimating the drift in the sampling frequency accordingly. It should be emphasized that, the channel conditions such as multipath and delay spread, and ambient noise is considered to make the system pragmatic. A joint prediction of the node mobility and speed are estimated based on the sampling frequency offset estimation. This sampling frequency offset drift is detected based on correlating an anticipated window in the orthogonal frequency division multiplexing (OFDM) of the received packet. The range and the distance of the mobile node is predicted from estimating the speed at the received packet and reused in the position estimation algorithm. The underwater acoustic channel is considered in this paper with 8 paths and maximum delay spread of 48 ms to simulate a pragmatic case. The performance is evaluated by adopting different nodes speeds in the simulation in two scenarios of expansion and compression. The results show that the proposed algorithm has a stable profile in the presence of severe channel conditions. Also, the result shows that the maximum speed that can be adopted in this algorithm is 9 km/h and the expansion case profile is more stable than the compression scenario. In addition, a comparison with a dynamic triangular algorithm (DTN) is presented in order to evaluate the proposed system.
LBRP: A RESILIENT ENERGY HARVESTING NOISE AWARE ROUTING PROTOCOL FOR UNDER WA...ijfcstjournal
Underwater detector network is one amongst the foremost difficult and fascinating analysis arenas that open the door of pleasing plenty of researchers during this field of study. In several under water based
sensor applications, nodes are square measured and through this the energy is affected. Thus, the mobility of each sensor nodes are measured through the water atmosphere from the water flow for sensor based protocol formations. Researchers have developed many routing protocols. However, those lost their charm with the time. This can be the demand of the age to supply associate degree upon energy-efficient and ascendable strong routing protocol for under water actuator networks. During this work, the authors tend to propose a customary routing protocol named level primarily based routing protocol (LBRP), reaching to offer strong, ascendable and energy economical routing. LBRP conjointly guarantees the most effective use of total energy consumption and ensures packet transmission which redirects as an additional reliability in compare to different routing protocols. In this work, the authors have used the level of forwarding node, residual energy and distance from the forwarding node to the causing node as a proof in multicasting technique comparisons. Throughout this work, the authors have got a recognition result concerning about
86.35% on the average in node multicasting performances. Simulation has been experienced each in a wheezy and quiet atmosphere which represents the endorsement of higher performance for the planned protocol.
LBRP: A RESILIENT ENERGY HARVESTING NOISE AWARE ROUTING PROTOCOL FOR UNDER WA...ijfcstjournal
Underwater detector network is one amongst the foremost difficult and fascinating analysis arenas that
open the door of pleasing plenty of researchers during this field of study. In several under water based
sensor applications, nodes are square measured and through this the energy is affected. Thus, the mobility
of each sensor nodes are measured through the water atmosphere from the water flow for sensor based
protocol formations. Researchers have developed many routing protocols. However, those lost their charm
with the time. This can be the demand of the age to supply associate degree upon energy-efficient and
ascendable strong routing protocol for under water actuator networks. During this work, the authors tend
to propose a customary routing protocol named level primarily based routing protocol (LBRP), reaching to
offer strong, ascendable and energy economical routing. LBRP conjointly guarantees the most effective use
of total energy consumption and ensures packet transmission which redirects as an additional reliability in
compare to different routing protocols. In this work, the authors have used the level of forwarding node,
residual energy and distance from the forwarding node to the causing node as a proof in multicasting
technique comparisons. Throughout this work, the authors have got a recognition result concerning about
86.35% on the average in node multicasting performances. Simulation has been experienced each in a
wheezy and quiet atmosphere which represents the endorsement of higher performance for the planned
protocol.
LBRP: A RESILIENT ENERGY HARVESTING NOISE AWARE ROUTING PROTOCOL FOR UNDER WA...ijfcstjournal
Underwater detector network is one amongst the foremost difficult and fascinating analysis arenas that open the door of pleasing plenty of researchers during this field of study. In several under water based sensor applications, nodes are square measured and through this the energy is affected. Thus, the mobility of each sensor nodes are measured through the water atmosphere from the water flow for sensor based protocol formations. Researchers have developed many routing protocols. However, those lost their charm with the time. This can be the demand of the age to supply associate degree upon energy-efficient and ascendable strong routing protocol for under water actuator networks. During this work, the authors tend to propose a customary routing protocol named level primarily based routing protocol (LBRP), reaching to offer strong, ascendable and energy economical routing. LBRP conjointly guarantees the most effective use of total energy consumption and ensures packet transmission which redirects as an additional reliability in compare to different routing protocols. In this work, the authors have used the level of forwarding node, residual energy and distance from the forwarding node to the causing node as a proof in multicasting technique comparisons. Throughout this work, the authors have got a recognition result concerning about 86.35% on the average in node multicasting performances. Simulation has been experienced each in a wheezy and quiet atmosphere which represents the endorsement of higher performance for the planned protocol.
Geographic routing protocols for underwater wireless sensor networks a surveyijwmn
Underwater wireless sensor networks (UWSN), similar to the terrestrial sensor networks, have different
challenges such as limited bandwidth, low battery power, defective underwater channels, and high variable
propagation delay. A crucial problem in UWSN is finding an efficient route between a source and a
destination. Consequently, great efforts have been made for designing efficient protocols while considering
the unique characteristics of underwater communication. Several routing protocols are proposed for this
issue and can be classified into geographic and non-geographic routing protocols. In this paper we focus
on the geographic routing protocols. We introduce a review and comparison of different algorithms
proposed recently in the literature. We also presented a novel taxonomy of these routing in which the
protocols are classified into three categories (greedy, restricted directional flooding and hierarchical)
according to their forwarding strategies.
Seawater salinity modelling based on electromagnetic wave characterizationIJECEIAES
Wireless communications have experienced tremendous growth, and improving their performance based on specific parameters requires an accurate model. Salt seawater, being an abundant resource, could play a crucial role in various applications such as enhancing electrical conductivity, monitoring security, improving battery power efficiency, and creating liquid antennas. Salinity is an essential factor to consider when developing these applications. This paper focused on investigating the electromagnetic properties of seawater salinity in the context of marine wireless communications. The results of the study showed that salinity has a significant impact on the Fresnel reflection coefficient in terms of magnitude, phase shift, and polarization, and can either constructively or destructively affect it. The new model paved the way for the development of an integrated salt seawater model that addressed the complex salinity issues involved in these applications.
Fuzzy based clustering and energy efficientIJCNCJournal
Underwater Wireless Sensor Network (UWSN) is a particular kind of sensor networks which is
characterized by using acoustic channels for communication. UWSN is challenged by great issues specially
the energy supply of sensor node which can be wasted rapidly by several factors. The most proposed
routing protocols for terrestrial sensor networks are not adequate for UWSN, thus new design of routing
protocols must be adapted to this constrain. In this paper we propose two new clustering algorithms based
on Fuzzy C-Means mechanisms. In the first proposition, the cluster head is elected initially based on the
closeness to the center of the cluster, then the node having the higher residual energy elects itself as a
cluster head. All non-cluster head nodes transmit sensed data to the cluster head. This latter performs data
aggregation and transmits the data directly to the base station. The second algorithm uses the same
principle in forming clusters and electing cluster heads but operates in multi-hop mode to forward data
from cluster heads to the underwater sink (uw-sink). Furthermore the two proposed algorithms are tested
for static and dynamic deployment. Simulation results demonstrate the effectiveness of the proposed
algorithms resulting in an extension of the network lifetime.
An energy aware scheme for layered chain in underwater wireless sensor networ...IJECEIAES
Extending the network lifetime is a very challenging problem that needs to be taken into account during routing data in wireless sensor networks in general and particularly in underwater wireless sensor networks (UWSN). For this purpose, the present paper proposes a multilayer chain based on genetic algorithm routing (MCGA) for routing data from nodes to the sink. This algorithm consists to create a limited number of local chains constructed by using genetic algorithm in order to obtain the shortest path between nodes; furthermore, a leader node (LN) is elected in each chain followed by constructing a global chain containing LNs. The selection of the LN in the closest chain to the sink is as follows: Initially, the closest node to sink is elected LN in this latter because all nodes have initially the same energy value; then the future selection of the LN is based on the residual energy of the nodes. LNs in the other chains are selected based on the proximity to the previous LNs. Data transmission is performed in two steps: intra-chain transmission and inter-chain transmission. Furthermore, MCGA is simulated for different scenarios of mobility and density of nodes in the networks. The performance evaluation of the proposed technique shows a considerable reduction in terms of energy consumption and network lifespan.
On performance analysis of non-orthogonal multiple access downlink for cellul...IJECEIAES
This paper presents the unmanned aerial vehicle (UAV) relays’ assisted vehicle-to-everything (V2X) network to implement the internet of things (IoT) systems with improvement in the coverage area. Such a network benefits from many advantages of the non-orthogonal multiple access (NOMA) scheme. We have implemented a decode-and-forward (DF) scheme for these UAVs. Then, we characterize the channels as Nakagami-m fading to evaluate the performance of the system. We derive closed-form expressions of outage probability (OP), ergodic capacity (EC), and throughput. The results show that the performance of the system depends on the transmitted signal-to-noise ratio (SNR) at the base station and the heights of the UAV relays. Target rate and power allocation factors are two main parameters that can be adjusted to achieve better performance. The results also compare to the system without UAV and OMA technique that shows the advantages of deploying UAV-assisted NOMA. Therefore, the design of NOMA for UAV relay-assisted V2X systems provides sufficient demand. The simulation results verified the effectiveness of the proposed UAV network and the precision of the theoretical analysis.
The Underwater Sensor Network (UWSN) is main interesting area due to its most valuable
applications like: disaster preventions, distributed tactical surveillance, undersea exploration, seismic
monitoring, environmental monitoring and many more. The design of energy efficient routing protocol
however is a challenging issue because in underwater environment the batteries of the sensor nodes
cannot be recharged easily. Majority of the researchers have adapted the terrestrial WSN methodologies
to overcome this problem but in underwater environment the terrestrial WSN approach is not feasible due
to the acoustic signaling and water current. This research paper focuses the key limitation of the current
energy efficient routing protocols. The simulation results with comparative analysis for energy efficient
routing protocols are also presented in this research article; which helps the researchers to find the further
research gap in the field of energy efficient routing protocols.
Abstract: The growing demand on wireless communication service has created the necessity to support higher data rates for multimedia services. .As next generation wireless communication networks are expected to provide broadband multimedia services such as voice, web browsing, video conferencing etc. For high data rate achievement one must enhance the capacity of the wireless communication system. The capacity of a communication system can be enhanced by using OFDM system. OFDM is commonly used for communication system due to its high transmission rate and robustness against multipath fading So as to enhance the capacity of fading channels the OFDM system are combined to form hybrid system. Capacity is the measure of maximum information that can be transmitted reliably over a channel. This paper review on different channel capacity enhancement techniques used in OFDM system is SVD (Singular Value Decomposition), water Filling algorithm.
STATE-OF-THE-ART OF THE PHYSICAL LAYER IN UNDERWATER WIRELESS SENSOR NETWORKSijwmn
With the current technology revolution, underwater wireless sensor networks (UWSNs) find several applications such as disaster prevention, water quality monitoring, military surveillance and fish farming. Nevertheless, this kind of networks faces a number of challenges induced by the nature of the underwater environment and its influence on the network physical media. Therefore, the ultimate objective of this paper is to lay down the key aspects of the physical layer of the underwater sensor networks (UWSNs). It discusses issues related to the characteristics and challenges of the underwater communication channel, differences between terrestrial wireless sensor networks and UWSNs, and acoustic propagation models in underwater. The paper also surveys some of the underwater acoustic modems. This study is essential to better understand the challenges of designing UWSNs and alleviate their effects.
We make use of the existence of cell-disjoint paths in the 3D grid topology to design a new highly reliable adaptive geographic routing protocol called Grid-based Adaptive Routing Protocol (GARP) for Underwater Wireless Sensor Networks. In GARP, the underwater environment is viewed as a virtual 3D grid of cells. A packet is forwarded following a pre-constructed routing path from a node in a grid cell to a node in a neighbouring grid cell repeatedly until the destination sink node is reached. When a selected routing path becomes unavailable, GARP adapts to the condition by switching to an alternative path making use of the existing cell-disjoint paths. Since the protocol uses pre-constructed routing paths, it avoids path establishment and path maintenance overheads. Analytical performance evaluation results for GARP are obtained showing its high reliability. In tested cases, the delivery ratio has approached 100% when the network density has reached a minimum number of sensor nodes per grid cell.
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LBRP: A RESILIENT ENERGY HARVESTING NOISE AWARE ROUTING PROTOCOL FOR UNDER WA...ijfcstjournal
Underwater detector network is one amongst the foremost difficult and fascinating analysis arenas that open the door of pleasing plenty of researchers during this field of study. In several under water based sensor applications, nodes are square measured and through this the energy is affected. Thus, the mobility of each sensor nodes are measured through the water atmosphere from the water flow for sensor based protocol formations. Researchers have developed many routing protocols. However, those lost their charm with the time. This can be the demand of the age to supply associate degree upon energy-efficient and ascendable strong routing protocol for under water actuator networks. During this work, the authors tend to propose a customary routing protocol named level primarily based routing protocol (LBRP), reaching to offer strong, ascendable and energy economical routing. LBRP conjointly guarantees the most effective use of total energy consumption and ensures packet transmission which redirects as an additional reliability in compare to different routing protocols. In this work, the authors have used the level of forwarding node, residual energy and distance from the forwarding node to the causing node as a proof in multicasting technique comparisons. Throughout this work, the authors have got a recognition result concerning about 86.35% on the average in node multicasting performances. Simulation has been experienced each in a wheezy and quiet atmosphere which represents the endorsement of higher performance for the planned protocol.
Geographic routing protocols for underwater wireless sensor networks a surveyijwmn
Underwater wireless sensor networks (UWSN), similar to the terrestrial sensor networks, have different
challenges such as limited bandwidth, low battery power, defective underwater channels, and high variable
propagation delay. A crucial problem in UWSN is finding an efficient route between a source and a
destination. Consequently, great efforts have been made for designing efficient protocols while considering
the unique characteristics of underwater communication. Several routing protocols are proposed for this
issue and can be classified into geographic and non-geographic routing protocols. In this paper we focus
on the geographic routing protocols. We introduce a review and comparison of different algorithms
proposed recently in the literature. We also presented a novel taxonomy of these routing in which the
protocols are classified into three categories (greedy, restricted directional flooding and hierarchical)
according to their forwarding strategies.
Seawater salinity modelling based on electromagnetic wave characterizationIJECEIAES
Wireless communications have experienced tremendous growth, and improving their performance based on specific parameters requires an accurate model. Salt seawater, being an abundant resource, could play a crucial role in various applications such as enhancing electrical conductivity, monitoring security, improving battery power efficiency, and creating liquid antennas. Salinity is an essential factor to consider when developing these applications. This paper focused on investigating the electromagnetic properties of seawater salinity in the context of marine wireless communications. The results of the study showed that salinity has a significant impact on the Fresnel reflection coefficient in terms of magnitude, phase shift, and polarization, and can either constructively or destructively affect it. The new model paved the way for the development of an integrated salt seawater model that addressed the complex salinity issues involved in these applications.
Fuzzy based clustering and energy efficientIJCNCJournal
Underwater Wireless Sensor Network (UWSN) is a particular kind of sensor networks which is
characterized by using acoustic channels for communication. UWSN is challenged by great issues specially
the energy supply of sensor node which can be wasted rapidly by several factors. The most proposed
routing protocols for terrestrial sensor networks are not adequate for UWSN, thus new design of routing
protocols must be adapted to this constrain. In this paper we propose two new clustering algorithms based
on Fuzzy C-Means mechanisms. In the first proposition, the cluster head is elected initially based on the
closeness to the center of the cluster, then the node having the higher residual energy elects itself as a
cluster head. All non-cluster head nodes transmit sensed data to the cluster head. This latter performs data
aggregation and transmits the data directly to the base station. The second algorithm uses the same
principle in forming clusters and electing cluster heads but operates in multi-hop mode to forward data
from cluster heads to the underwater sink (uw-sink). Furthermore the two proposed algorithms are tested
for static and dynamic deployment. Simulation results demonstrate the effectiveness of the proposed
algorithms resulting in an extension of the network lifetime.
An energy aware scheme for layered chain in underwater wireless sensor networ...IJECEIAES
Extending the network lifetime is a very challenging problem that needs to be taken into account during routing data in wireless sensor networks in general and particularly in underwater wireless sensor networks (UWSN). For this purpose, the present paper proposes a multilayer chain based on genetic algorithm routing (MCGA) for routing data from nodes to the sink. This algorithm consists to create a limited number of local chains constructed by using genetic algorithm in order to obtain the shortest path between nodes; furthermore, a leader node (LN) is elected in each chain followed by constructing a global chain containing LNs. The selection of the LN in the closest chain to the sink is as follows: Initially, the closest node to sink is elected LN in this latter because all nodes have initially the same energy value; then the future selection of the LN is based on the residual energy of the nodes. LNs in the other chains are selected based on the proximity to the previous LNs. Data transmission is performed in two steps: intra-chain transmission and inter-chain transmission. Furthermore, MCGA is simulated for different scenarios of mobility and density of nodes in the networks. The performance evaluation of the proposed technique shows a considerable reduction in terms of energy consumption and network lifespan.
On performance analysis of non-orthogonal multiple access downlink for cellul...IJECEIAES
This paper presents the unmanned aerial vehicle (UAV) relays’ assisted vehicle-to-everything (V2X) network to implement the internet of things (IoT) systems with improvement in the coverage area. Such a network benefits from many advantages of the non-orthogonal multiple access (NOMA) scheme. We have implemented a decode-and-forward (DF) scheme for these UAVs. Then, we characterize the channels as Nakagami-m fading to evaluate the performance of the system. We derive closed-form expressions of outage probability (OP), ergodic capacity (EC), and throughput. The results show that the performance of the system depends on the transmitted signal-to-noise ratio (SNR) at the base station and the heights of the UAV relays. Target rate and power allocation factors are two main parameters that can be adjusted to achieve better performance. The results also compare to the system without UAV and OMA technique that shows the advantages of deploying UAV-assisted NOMA. Therefore, the design of NOMA for UAV relay-assisted V2X systems provides sufficient demand. The simulation results verified the effectiveness of the proposed UAV network and the precision of the theoretical analysis.
The Underwater Sensor Network (UWSN) is main interesting area due to its most valuable
applications like: disaster preventions, distributed tactical surveillance, undersea exploration, seismic
monitoring, environmental monitoring and many more. The design of energy efficient routing protocol
however is a challenging issue because in underwater environment the batteries of the sensor nodes
cannot be recharged easily. Majority of the researchers have adapted the terrestrial WSN methodologies
to overcome this problem but in underwater environment the terrestrial WSN approach is not feasible due
to the acoustic signaling and water current. This research paper focuses the key limitation of the current
energy efficient routing protocols. The simulation results with comparative analysis for energy efficient
routing protocols are also presented in this research article; which helps the researchers to find the further
research gap in the field of energy efficient routing protocols.
Abstract: The growing demand on wireless communication service has created the necessity to support higher data rates for multimedia services. .As next generation wireless communication networks are expected to provide broadband multimedia services such as voice, web browsing, video conferencing etc. For high data rate achievement one must enhance the capacity of the wireless communication system. The capacity of a communication system can be enhanced by using OFDM system. OFDM is commonly used for communication system due to its high transmission rate and robustness against multipath fading So as to enhance the capacity of fading channels the OFDM system are combined to form hybrid system. Capacity is the measure of maximum information that can be transmitted reliably over a channel. This paper review on different channel capacity enhancement techniques used in OFDM system is SVD (Singular Value Decomposition), water Filling algorithm.
STATE-OF-THE-ART OF THE PHYSICAL LAYER IN UNDERWATER WIRELESS SENSOR NETWORKSijwmn
With the current technology revolution, underwater wireless sensor networks (UWSNs) find several applications such as disaster prevention, water quality monitoring, military surveillance and fish farming. Nevertheless, this kind of networks faces a number of challenges induced by the nature of the underwater environment and its influence on the network physical media. Therefore, the ultimate objective of this paper is to lay down the key aspects of the physical layer of the underwater sensor networks (UWSNs). It discusses issues related to the characteristics and challenges of the underwater communication channel, differences between terrestrial wireless sensor networks and UWSNs, and acoustic propagation models in underwater. The paper also surveys some of the underwater acoustic modems. This study is essential to better understand the challenges of designing UWSNs and alleviate their effects.
We make use of the existence of cell-disjoint paths in the 3D grid topology to design a new highly reliable adaptive geographic routing protocol called Grid-based Adaptive Routing Protocol (GARP) for Underwater Wireless Sensor Networks. In GARP, the underwater environment is viewed as a virtual 3D grid of cells. A packet is forwarded following a pre-constructed routing path from a node in a grid cell to a node in a neighbouring grid cell repeatedly until the destination sink node is reached. When a selected routing path becomes unavailable, GARP adapts to the condition by switching to an alternative path making use of the existing cell-disjoint paths. Since the protocol uses pre-constructed routing paths, it avoids path establishment and path maintenance overheads. Analytical performance evaluation results for GARP are obtained showing its high reliability. In tested cases, the delivery ratio has approached 100% when the network density has reached a minimum number of sensor nodes per grid cell.
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Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
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More examples of our work https://www.r-r-consult.dk/en/cases-en/
Final project report on grocery store management system..pdfKamal Acharya
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Student information management system project report ii.pdfKamal Acharya
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1. A Hybrid RF/FSO and Underwater VLC
Cooperative Relay Communication System
Mohammad Furqan Ali∗, Tharindu D. Ponnimbaduge Perera∗,Dushantha Nalin K. Jayakody∗† and Sahil Garg∗,
∗School of Computer Science and Robotics, National Research Tomsk Polytechnic University, RUSSIA
†School of Postgraduate Studies, Sri Lanka Technological Campus, SRI LANKA
‡Department, Ecole de Technologie Superieure, Universite du Quebec, Montreal, Canada
Email:[ali89, ponnimbaduage, nalin, stefanpnc]@tpu.ru, morapitiya18@gmail.com, sahil.garg@ieee.org
Abstract—Underwater wireless communication (UWC) has
become a significant technique that is used to investigate the
underwater environment. It is also noteworthy that the collected
data from underwater has to transmit to inland data fusion
centers for further investigation and operating instructions need
to transmit from the inland center to underwater autonomous
vehicles (UAVs) to operate as per the real-time requirements.
Therefore, a hybrid terrestrial and UWC setup is required in
most of the underwater military and commercial applications.
In this paper, a dual-hop hybrid terrestrial and underwater co-
operative communication system has been investigated. A floating
buoy works as a relay node to assist information transmission
and visible light communication (VLC) is used for UWC. Free-
space optics (FSO) and RF are used as potential candidates for
terrestrial communication link of the proposed system. Numerical
results show that FSO-VLC combination has the superior bit-
error-rate (BER) performance with compare to RF-VLC setup
in higher SNR conditions regardless of the water mediums.
Index Terms—Cooperative communication, Free space optical
communication (FSO), Underwater wireless communication
(UWC), Visible light communication (VLC).
I. INTRODUCTION
Earth is a water planet, occupied more than 70% of its
surface by water and 95% of such water areas are still
unexplored to envisage underwater phenomenal activities. Due
to an evolutionary revolution and growing interest of human
activities in exploring the undersea environment, UWC has
received significant attention from the wireless communication
research community. Various underwater applications have
been introduced in existing open literature such as marine
life, oil and gas rig monitoring systems, water pollution
control systems and early detection warning of earthquakes
and tsunami [1]. Acoustic, optical and radio frequency (RF)
wireless carriers are used as potential candidates for UWC [2].
Optical signaling provides a high bandwidth data rate with low
latency and is particularly appealing for real-time underwater
applications [3]. Visible light as a the most favorable candidate
for the UWC [4]. In addition, visible light communication
(VLC) is relatively cost-effective and easy to deploy in various
underwater applications over a short distance (up to 50 m)
[5]. VLC has been recognized as a promising alternative and
complementary communication technology to data transfer in
various applications. It has gained an attraction as a potential
wireless candidate for signal transmission in underwater en-
vironment. For underwater wireless communication scenario,
It is easy to install in harsh channel conditions and supports
larger bandwidth along with secured communication unlike
RF communication.
Motivated of this paper, and summarizing above mentioned
facts, we are investigating the BER performance comparison
for two different dual-hop hybrid cooperative relay based com-
munication system models in different underwater mediums
along with strong channel conditions. Dual-hop communi-
cation link has been proposed for a fair solution over long
ranges. In both of the system models, the signal broadcasting
from terrestrial base station to underwater based relay through
RF or FSO link whereas the information forwards to the
destination from relay with VLC (common for both system
models) link. Underwater VLC (UVLC) link considered as
under the combined influence of turbulence and pointing error
impairments of water channel. Additionally, VLC technology
does not interfere with RF waves and it is safe to use in various
applications. It has fruitful future prospects, because of popu-
larity of LEDs. Thus, VLC has shown a potential acceptability
for next generation communication systems for revolution in
the communication era. UVLC has been investigated in most
of the recent existing works on UWC systems [6]–[9]. The
authors in [6], have investigated performance analysis of a
vertical underwater VLC link between the two corresponding
points. Moreover, unlike the horizontal underwater VLC links,
the authors have modeled vertical VLC link with varying
turbulence strength based on the depth-dependant temperature
and salinity. The performance analysis of vertical underwater
VLC link considering the strong water turbulence conditions
is investigated in [7]. The authors have used Gamma-Gamma
probability density function to model strong turbulence in
underwater VLC and formulated a closed-form bit error rate
(BER) expression in underwater based destination. The per-
formance of vertical underwater VLC links, which are subject
to both strong turbulence and pointing errors is investigated in
[8]. In [9], the authors have carried out a detailed underwater
VLC channel modeling and characterization study taking into
account the presence of human and man-made objects. It
is shown that even in complete line-of-site (LOS) blockage,
transmission can take place due to scattering without being
2. affected by the increase in path-loss.
Dual-hop communication has been used to improve system
performance for long-range communication links. In order
to operate and control unmanned autonomous underwater
vehicle (UAUV) along with the real-time data transmission
in underwater, a high demand of dual-hop cooperative hybrid
terrestrial and underwater communication system is required
for numerous underwater applications [10]. A dual-hop un-
derwater RF and underwater wireless optical communication
(UWO) system has been investigated in [10] [11]. In [10], the
authors have examined the secrecy performance of a dual-hop
mixed RF/UWO system and formulated the average secrecy
capacity metrics for the fixed-gain relaying scheme. The more
similar work has been carried out and investigated on secrecy
performance and outage probability of a dual-hop mixed
RF-UWO system in [11]. The authors have shown that the
secrecy performance of the system improves significantly by
increasing the parameters of the legitimate link. Recently, an
efficient alternative signal transmission technique, free-space
optical (FSO) communication over lognormal turbulence chan-
nel conditions has been widely advocated in open literature
[12] [13]. Thus, mixed RF/FSO systems have been extensively
investigated in open literature [14]. In most recent work, based
on wireless energy harvested relay underwater cooperative
communication technique investigated in [15]. The authors
in [15], proposed the simultaneous wireless information and
power transmission (SWIPT) technique with the underwater
based relay. In [16], the authors have conducted a performance
analysis of dual-hop mixed RF/FSO system, where both RF
and FSO links are subjected to Nakagami-m and Gamma-
Gamma fading channels, respectively.
However, to the best of our knowledge, there is no per-
formance evaluation has been conducted between RF-VLC
and FSO-VLC dual-hop hybrid terrestrial and underwater
cooperative communication systems in the open literature.
Thus, in this paper, we investigate the performance differences
of RF-VLC and FSO-VLC dual-hop communications systems
by analyzing the BER performance at the underwater AUV
in different water. We model underwater VLC channel sub-
ject to both turbulence and pointing errors. For the system
performance analysis and comparison both of mixed dual-
hop communication, we have used an identical VLC link and
a similar distance between terrestrial base station to floating
buoy (relay node) in both RF-VLC and FSO-VLC cooperative
communication systems.
The remainder of the paper is organized into five sections. In
Section II, we obtain Bit-error-rate (BER) performance from
our simulation results, in RF and FSO links in each system
model proposed by Fig.1. In Section III, BER performance
calculated by implementing of on-off-keying modulation tech-
nique. In Section IV, the simulation results are presented to
identify of system performance of proposed models. Finally,
Section V concludes the paper.
II. SYSTEM MODEL
In this paper, we are considering the two dual-hop hybrid
terrestrial and underwater cooperative communication systems
as shown in Fig.1. The proposed systems are consists of one
inland base station (s), floating buoy as a relay node (r) and
a remotely operated AUV as the destination node (d) located
in underwater. Inland base station transmits information to the
underwater AUV via floating buoy using decode-and-forward
(DF) relay protocol. It is assumed that all three nodes are
equipped with single antenna and work in the half-duplex
mode. Except for the terrestrial communication link, all other
parameters of the systems are identical to each other. System
model-1 (SM1) uses RF in terrestrial communication link
while the other system model-2 (SM2) used FSO link. RF link
in SM1 is experienced Rayleigh fast fading and corresponding
channel coefficient is denoted as hRF . The channel power gain
represents as h2
RF , which follows the exponential distribution.
We use hF SO = hlhpht to denote the channel coefficient
experience in FSO terrestrial link in SM2, where hl denotes
the path loss, hp denotes the pointing errors between the
source (transmitter) and the relay as a signal receiver and
atmospheric turbulence is assigned by the ht. Note that the hl
is deterministic, and ht and hp are random variables follow-
ing Gaussian and Gamma-Gamma probabilistic distributions
respectively [17]. Detailed optical channel model of FSO link
is provided in Section III. An underwater VLC communication
link is common for both systems and the channel coefficient
is explained in detail in subsection D. The additive white
Gaussian noise (AWGN) with zero mean and variance σ2
xy
is used to model noise between communication nodes, where
x, y ∈ {s, r, d}. Similarly, the distance apart communication
nodes are represented as dα
xy, where α annotates the pathloss
exponent.
Fig. 1. A proposed system model of dual-hop hybrid cooperative RFVLC
underwater wireless communication, where source communicates with des-
tination through relay in different communication link along with different
channel conditions
3. A. SM1-Source to Relay (s-r) Communication RF Link
In SM1, the RF link is used for the communication between
the source and the relay node. The received signal at the
floating buoy can be written as,
yRF =
s
Ps
dα
sr
hRF x + nsr, (1)
where Ps is the signal transmission power of the inland base
station, x denotes the BPSK modulated information symbol,
dsr is the distance between the inland base station and floating
buoy and nsr assigns as AWGN noise experience by the RF
link. Thus, signal-to-noise ration (SNR) at the surface buoy
can be expressed as,
γRF =
Psd−α
sr h2
RF
σ2
sr
, (2)
where σ2
sr denoted as the noise variance of the AWGN. The
surface buoy decodes the received information signal and
forward the regenerated information signal to the AUV through
VLC link in the underwater environment.
B. SM2-Source to Relay (s-r) FSO Communication Link
In SM2, the inland base station uses FSO link to send
information to the surface buoy. In FSO communication link,
signal propagation depends on geometrical constraints of the
system, such as electrical to optical conversion efficiency (η1)
and photo-detector responsivity (r1) of photo-diode. Thus, At
the floating buoy, the received signal through FSO link can be
calculated as,
yF SO =
p
Psη1r1hF SOx + nsr, (3)
The SNR of the FSO link at the buoy can be expressed as
γF SO =
Psη1
2
r1
2
h2
F SO
σ2
rs
. (4)
III. OPTICAL CHANNEL MODEL
In FSO signal propagation, the channel is impaired by
channel fading. Thus, FSO channel hF SO is modeled by
pathloss (hl), considering the atmospheric absorption and
scattering cause attenuation, atmospheric turbulence (ht) and
misalignment also known as pointing errors (hp). The normal-
ized channel coefficient of the FSO link can be described as
in [17],
hF SO = hlhpht. (5)
A. Atmospheric Attenuation
Optical signal affected by attenuation is also known as the
extinction coefficient, which includes atmospheric absorption
and scattering. The attenuation coefficient considered as a
fixed factor of which has no randomness exists in its behavior.
The attenuation coefficient depends on the physical constraints
and distribution of scattering signals and the wavelength
utilized [17]. Thus, adhering to Beer-Lambert law, the path
loss of the FSO link can be given as,
hl(λ, L) =
P(λ, L)
P(λ, 0)
= exp{−c1(λ)L}, (6)
where the distance apart inland base station and the buoy is
denoted by L, P(λ, L) is the transmitted signal power for the
given distance L. However, c1(λ) is an extinction coefficient
which is the total sum of optical absorption and scattering by
the atmospheric conditions.
B. Turbulence Channel Fading Model
In existing works of literature has many statistical channel
models for weak turbulence intensity fluctuation probability
density function (PDF) are experimentally modeled as the log-
normal distribution [18]. In recent work with related FSO com-
munication, a Gamma-Gamma probability distribution was
used to model atmospheric turbulence related channel fading.
According to [17], the PDF of atmospheric turbulence ht is
given as,
fht(ht) = 2
(αβ)
(α+β)
2
Γ(α)Γ(β)
(ht)
(α+β)
2 −1
Kα−β(2
p
αβht), (7)
where the term K(α−β)(·) is defined as the modified Bessel
function of the second kind, α and β are defined as the large
scale variance and small scale variance, respectively [17].
C. Pointing Error
The pointing error is an another parameter of fading in
line of sight (LOS) optical communications. In the LOS,
FSO communication, pointing accuracy is a crucial factor in
determining system performance and reliability. The pointing
error may occur due to the flexible pace of the transmitter and
receiver or due to wind loads, thermal expansions, etc. The
pointing error fading coefficient can be written as [17],
hp = Aoexp
−
2a2
w2
zeq
, (8)
where a denotes the random radial displacement at the signal
receiver and A0 is the fraction of the collected power at the
displacement randomness of a = 0. The displacement of
randomness (a) depends on the horizontal and vertical move-
ments of signal receiver and wzeq represents the equivalent
beamwidth.
D. Relay Buoy to AUV VLC Link
Buoy to AUV communication link is modeled using vertical
VLC, where relay buoy forwards the information received
from the inland base station to the AUV. It is also noteworthy
that the VLC link is common in both SM1 and SM2. The
buoy is assumed to be placed at a fixed location on the sea
surface with a laser diode (LD) directing vertically towards
the stationary AUV. Thus, the received signal at the AUV can
be expressed as,
yV LC =
p
Prη2r2hV LCx̄ + nrd, (9)
4. where Pr the relay buoy’s transmission signal power, η2 is
electrical to optical conversion efficiency at the receiver and
r2 is the photo-detector responsivity. The random attenuation
propagation channel in VLC link is modeled by considering
three factors, i.e., path loss (h0
l) , atmospheric turbulence (h0
t)
and pointing errors (h0
p) [8]. Thus, underwater VLC channel
can be expressed as,
hV LC = (h0
l)(h0
t)(h0
p). (10)
E. VLC Underwater Attenuation Model
The path loss in the VLC link depends on the attenuation
coefficient c(λ). The attenuation coefficient is the sum of total
absorption a(λ) and scattering b(λ) of photons in underwater
environment. Thus, the underwater attenuation coefficient can
be expressed as in [19],
c(λ) = a(λ) + b(λ), (11)
The typical values of a(λ) and b(λ) in different types of water
medium are given in Table I. Thus, by considering (11), the
pathloss of the underwater VLC link can be expressed as [20],
h0
l = e−c(λ)dt
, (12)
where dt is the vertical LOS distance between relay buoy and
the underwater based AUV.
Description of water for
UWC
a(λ) b(λ) c(λ)
Pure sea water 0.053 0.003 0.056
Clear Ocean water 0.069 0.08 0.15
Coastal Ocean water 0.088 0.216 0.305
Turbid Harbor water 0.295 1.875 2.17
TABLE I
THE VALUES OF ABSORPTION, SCATTERING AND ATTENUATION
COEFFICIENTS IN DIFFERENT WATER MEDIUMS [21]
F. Underwater VLC Turbulence Channel Model
We consider the turbulence model proposed in [6]. In this
turbulence model, the authors have modeled the VLC under-
water vertical channel into successive k number of layers and
the fading coefficient associated with each distinct layers. The
fading coefficient is modeled as independent but not identically
distributed Gamma-Gamma random variables. Thus, Gamma-
Gamma pdf for the kth
layer can be given as [8],
fhtk
(h0
tk
) = 2
(αkβk)
(αk+βk)
2
Γ(αk)Γ(βk)
(h0
tk
)
(αk+βk)
2 −1
Kαk−βk
(2
p
αkβkhtk
),
(13)
where Γ(·) is the Gamma function and K(αk−βk)(·) defined
as the modified Bessel function of the second kind. The
consideration of kth
layers in the underwater environment for
scattering process, the large scale cells and small scale cells
are defined by αk and βk respectively, which can be written
as, respectively
αk =
exp
0.49σ2
h0
tk
1 + 1.11σ
12
5
h0
tk
7
6
− 1
−1
, (14)
βk =
exp
0.51σ2
h0
tk
1 + 0.69σ
12
5
h0
tk
5
6
− 1
−1
. (15)
where σ2
h0
tk
represent the scintillation index for plane wave
model known as Rytov variance [7].
G. Pointing Error In Underwater VLC Link
Pointing error is also one another source of fading in un-
derwater VLC link. Pointing error occurs due to misalignment
phenomena and tilting position of buoy’s transmitter and/or
AUV’s receiver due to ocean waves and currents. Thus, the
pointing error can be represented as [8],
h0
p = Aoexp
−
2R2
w0
zeq
2
, (16)
where Ao denoted as the fraction of the collected power at
the value of R = 0 and w0
zeq is the equivalent beam width of
underwater VLC link. The beam-width of the VLC link can
be written as w0
zeq = 2σsζ, where ζ is the ratio between of
equivalent beam radius which is the pointing error displace-
ment standard deviation denoted by the σs. The random radial
displacement R at the AUV’s receiver end, calculated by R
=
q
R2
x + R2
y. The displacement along horizontal and vertical
axes is defined by the fraction R2
x and R2
y respectively.
IV. BER PERFORMANCE AT THE DESTINATION
The proposed both of the system models, an underwater
VLC link is in common and consider as vertical link. The sig-
nal transmits to an underwater based AUV through transmis-
sion relay over the different channel conditions. Analytically,
in RF-VLC mixed communication link the average SNR at the
destination can be calculated as [10] [22],
γRF −V LC =
γRF γV LC
γV LC + 1
, (17)
For the FSO-VLC mixed communication the average SNR can
be calculated as
γF SO−V LC =
γF SOγV LC
γV LC + 1
, (18)
where γRF −V LC and γF SO−V LC the average SNR at the
underwater based destination, respectively. Based on (17) and
(18), a single-carrier system with simple modulation technique
as on-off keying (OOK) can be used [6]. The BER for OOK
over real AWGN channel mentioned in [23]. Based on (17), the
BER performance at the destination in SM1 can be calculated
as,
BERd =
Q
r
γRF −V LC
2
, (19)
5. -5 0 5 10 15 20 25
SNR, dB
10
-4
10
-3
10
-2
10
-1
10
0
Bit
Error
Rate
FSO Link
RF Link
Fig. 2. Comparison of BER performance at relay enabled RF and FSO link
Similarly, Based on (18), the BER performance at the desti-
nation in SM2 can be calculated as,
BER0
d =
Q
r
γF SO−V LC
2
. (20)
V. NUMERICAL RESULTS
In this section, we present the simulation results to inves-
tigate the BER performance of SM1 and SM2 at the AUV.
We considered the targeting destination located vertically in
underwater environment with respect to buoy. Unless other-
wise status, we use receiver aperture diameter of Dr = 15cm,
full width transmitter beam divergence angle θ = 6◦
, distance
between inland base station and buoy dsr = 200m and vertical
depth AUV from sea surface dt = 40m. The attenuation
coefficient value of 0.43 for clear air used in FSO link [24].
The corresponding values of pointing error parameters depend
on the fraction of the collected power Ao and equivalent
beam width ζ mentioned in [8]. In Fig.2, we present the
BER performance comparison between terrestrial RF and
FSO communication links at the buoy in both of proposed
system models. As we can clearly see from the Fig.2, FSO
link shows superior BER performance in higher transmitting
SNR conditions, while RF shows superior performance in
lower SNR conditions. However, in transmit SNR 17dB, both
the FSO and RF link show the similar BER performance.
Although, the achievable rate (AR) is out of scope of this
work, the comparison shows the superior BER performance
of the dual-hop hybrid underwater wireless communication.
In Fig.3, we compare the BER performance of SM1 and
SM2 at the AUV in different seawater types, i.e., pure, clear
and coastal water. It can clearly see from the Fig.3 that SM1
(RF-VLC) combination shows better BER performance com-
pare to SM2 (FSO-VLC) in lower SNR conditions regardless
-5 0 5 10 15 20 25
SNR, dB
10
-4
10
-3
10
-2
10
-1
10
0
Bit
Error
Rate
(SM1) RF/VLC in Pure Sea Water
(SM1) RF/VLC in Clear Sea Water
(SM1) RF/VLC in Coastal Sea Water
(SM2) FSO/VLC in Pure Sea Water
(SM2) FSO/VLC in Clear Sea Water
(SM2) FSO/VLC in Coastal Sea Water
Fig. 3. BER performance comparison of RF/VLC and FSO/VLC cooperative
communication in different water mediums
of the water type. However, SM2 (FSO-VLC) shows superior
BER performance in higher SNR, in all mentioned seawater
types. The best BER performance achieved in Fig.3 owns by
the SM2 (FSO-VLC) in pure, clear and coastal seawater. In
addition, Fig.3 proves the results obtained in Fig.2 showing
the similar pattern in BER performance.
In Fig.4, we present FSO and VLC pointing error effect
on the BER performance at the AUV in SM2 (FSO-VLC).
We assumed that both FSO and VLC link experience a
similar pointing error in this simulation. We use different
displacement standard deviation values as presented in Fig.4
to model pointing error. Corresponding pointing error values
are illustrated in the legends of the Fig.4. It can clearly
observed from Fig.4 that the effect on BER performance when
σs = 0.1 is negligible. However, as expected the effect on BER
performance is increased with the increase in displacement
standard deviation. It is also can be seen from the Fig.4 that the
BER performance curve’s slope is relatively has a low value
in higher σs conditions as compare to the lower σs values.
VI. CONCLUSION
In this paper, we investigate the BER performance of hybrid
terrestrial and underwater cooperative communication under
two different setups, where one setup consists of RF terrestrial
link and VLC underwater link while the other use FSO for the
terrestrial link. The floating buoy has been used as a relay to
assist information transmission between an inland base station
and underwater based AUV. Then we have compared the BER
performance at the relay buoy and the AUV to identify the
performance difference between the proposed two cooperative
system set-ups. Simulation results have shown that the FSO-
VLC combination has the superior BER performance in higher
transmitted SNR condition compare to RF-VLC cooperative
6. -5 0 5 10 15 20 25
SNR, dB
10
-4
10
-3
10
-2
10
-1
10
0
Bit
Error
Rate
Fig. 4. FSO and VLC Pointing error effect on BER performance at the AUV
in SM2(FSO/VLC).
setup. In addition, pointing error effect on BER performance
of the FSO-VLC setup also investigated.
VII. ACKNOWLEDGEMENT
This work was funded, in part, by the Scheme for Promotion
of Academic and Research Collaboration (SPARC), Ministry
of Human Resource Development, India under the No. P145,
in part, by the Russian Federation State Project Science, Grant
No. 8.13264.2018/8.9 and by the framework of Competitive-
ness Enhancement Program of the National Research Tomsk
Polytechnic University, in part, by the Academy of Finland
Grant No. 325692 and, in part, by the international cooperation
project of Sri Lanka Technological Campus, Sri Lanka and
Tomsk Polytechnic University, No. RRSG/19/5008 and COST
IRACON grant No. CA15104.
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