Wireless information and power transfer(WIPT) enables simultaneously communications and sustainable power supplement without the erection of power supply lines and the replacement operation of the batteries for the te...Wireless information and power transfer(WIPT) enables simultaneously communications and sustainable power supplement without the erection of power supply lines and the replacement operation of the batteries for the terminals. The application of WIPT to the underwater acoustic sensor networks(UWASNs) not only retains the long range communication capabilities, but also provides an auxiliary and convenient energy supplement way for the terminal sensors, and thus is a promising scheme to solve the energy-limited problem for the UWASNs. In this paper, we propose the integration of WIPT into the UWASNs and provide an overview on various enabling techniques for the WIPT based UWASNs(WIPT-UWASNs) as well as pointing out future research challenges and opportunities for WIPT-UWASNs.展开更多
Long propagation delay, limited bandwidth, and high bit error rate pose great challenges in media access control （MAC） protocol design for underwater acoustic networks. A MAC protocol called slotted floor acquisitio...Long propagation delay, limited bandwidth, and high bit error rate pose great challenges in media access control （MAC） protocol design for underwater acoustic networks. A MAC protocol called slotted floor acquisition multiple access （slotted-FAMA） suitable for underwater acoustic networks is proposed and analyzed. This FAMA based protocol adds a time slot mechanism to avoid DATA packet collisions. However, slotted-FAMA is not suitable for dense networks since the multiple request-to-send （RTS） attempts problem in dense networks is serious and greatly limits the network throughput. To overcome this drawback, this paper proposes a slotted-FAMA based MAC protocol for underwater acoustic networks, called RC-SFAMA. RC-SFAMA introduces an RTS competition mechanism to keep the network from high frequency of backoff caused by the multiple RTS attempts problem. Via the RTS competition mechanism, useful data transmission can be completed successfully when the situation of multiple RTS attempts occurs. Simulation results show that RC-SFAMA increases the network throughput efficiency as compared with slotted-FAMA, and minimizes the energy consumption.展开更多
Since mobile nodes such as autonomous underwater vehicles can effectively expand network coverage,underwater acoustic networks with mobile nodes have attracted more and more attention in recent years.To ensure the tim...Since mobile nodes such as autonomous underwater vehicles can effectively expand network coverage,underwater acoustic networks with mobile nodes have attracted more and more attention in recent years.To ensure the timely access of a mobile node without disturbing the normal transmission of data packets from static nodes,a sequence-scheduled and query-based medium access control protocol is proposed in this paper.The underwater nodes with data packets to be transmitted reply with a control packet for channel reservation after receiving the broadcast control packet of the buoy,then the reserved nodes transmit their data packets as the order calculated by the buoy.We develop a mechanism to adjust the transmission order of the control packets sent by the underwater nodes in the handshake phase to reduce the collision and guarantee the success rate of reservation,and a query is initiated when the reserved control packet of the mobile node is not received by the buoy in the handshake to respond to the data transmission request of the mobile node in time.Simulations show that the maximum nodal throughput of the proposed MAC protocol increases by at least 20%and the access delay of the mobile node decreases by about 90%,compared to the two reference protocols.Besides,the average access probability of the mobile node in the proposed protocol is more than 90%.展开更多
Zeroing neurodynamics methodology,which dedicates to finding equilibrium points of equations,has been proven to be a powerful tool in the online solving of problems with considerable complexity.In this paper,a method ...Zeroing neurodynamics methodology,which dedicates to finding equilibrium points of equations,has been proven to be a powerful tool in the online solving of problems with considerable complexity.In this paper,a method for underwater acoustic sensor network(UASN)localisation is proposed based on zeroing neurodynamics methodology to preferably locate moving underwater nodes.A zeroing neurodynamics model specifically designed for UASN localisation is constructed with rigorous theoretical analyses of its effectiveness.The proposed zeroing neurodynamics model is compatible with some localisation algorithms,which can be utilised to eliminate error in non‐ideal situations,thus further improving its effectiveness.Finally,the effectiveness and compatibility of the proposed zeroing neurodynamics model are substantiated by examples and computer simulations.展开更多
With the increasing demand for marine exploration, underwater acoustic sensor networks (UASNs) are prone to have the characteristics of large-scale, long term monitoring, and high data traffic load. Underwater media a...With the increasing demand for marine exploration, underwater acoustic sensor networks (UASNs) are prone to have the characteristics of large-scale, long term monitoring, and high data traffic load. Underwater media access control (MAC) protocols, which allow multiple users to share the common medium fairly and efficiently, are essential for the performance of UASNs. However, the design of MAC protocols is confronted with the challenges of spatial unfairness, data eruption, and low energy efficiency. In this paper, we propose a novel data concurrent transmission (DCT) MAC protocol, which is able to exploit long propagation delay and conduct concurrent transmission. Specifically, we present the theoretical performance analysis of the proposed MAC protocol in detail and give an analytical solution of the success concurrent transmission probability between nodes. In addition, simulation results are provided to demonstrate that our proposed protocol is appropriate for UASNs and can significantly improve the performance in terms of network throughput and energy consumption. Finally, we give some typical future applications of UASNs and discuss the demands on MAC protocol design.展开更多
Traditional underwater acoustic communication networks(UACNs)generally use omnidirectional transmission technology that causes a large number of data-packet collisions,thus resulting in low network throughput and high...Traditional underwater acoustic communication networks(UACNs)generally use omnidirectional transmission technology that causes a large number of data-packet collisions,thus resulting in low network throughput and high end-to-end delays.Compared with omnidirectional transmission technology,directional technology only sends and receives data packets in a specified direction.This can significantly reduce the probability of collisions and improve network performance.However,it also causes a deafness problem,which occurs when the sending node sends a data packet to the receiving node but the receiving node is unable to reply to the sender,because its antenna beam is closed.To resolve this issue,this study proposes a collision classification media access control(CC-MAC)protocol for UACNs.With this protocol,the underwater acoustic channel is divided into two subchannels,and the nodes transmit corresponding data types on them.The sending node can estimate the current status of the receiving node(i.e.,no collision,normal collision,deafness)according to the type of the data packet received and the sub-channel it arrived on,and it can choose correct options to improve network efficiency.Finally,we verify the performance of CC-MAC via simulations,showing that the protocol achieved higher network throughput and lower end-toend delays.展开更多
Cooperative jamming(CJ)is one of the important methods to solve security problems of underwater acoustic sensor networks(UASNs).In this paper,we propose a Cooperative Jamming Scheme based on Node Authentication for UA...Cooperative jamming(CJ)is one of the important methods to solve security problems of underwater acoustic sensor networks(UASNs).In this paper,we propose a Cooperative Jamming Scheme based on Node Authentication for UASNs to improve the effect of CJ by selecting suitable jamming source for found illegal nodes.In the node authentication,all nodes will be identified by their trust value(TV).TV is calculated according to three types of evidence:channel-based trust evidence,behavior-based trust evidence and energy-based trust evidence.Besides,to deal with cases where legal nodes may be suspected,the historical TV and trust redemption will be considered when calculating TV.In cooperative jamming,according to the link quality,several nodes are selected to jam illegal nodes.Both simulation and field experiment show that the proposed scheme can accurately find the illegal nodes in the time-vary channel and improve the security of the network.展开更多
Underwater Acoustic Sensor Network(UASN) has attracted significant attention because of its great influence on ocean exploration and monitoring. On account of the unique characteristics of underwater environment, loca...Underwater Acoustic Sensor Network(UASN) has attracted significant attention because of its great influence on ocean exploration and monitoring. On account of the unique characteristics of underwater environment, localization, as one of the fundamental tasks in UASNs, is a more challenging work than in terrestrial sensor networks. A survey of the ranging algorithms and the network architectures varied with different applications in UASNs is provided in this paper. Algorithms used to estimate the coordinates of the UASNs nodes are classified into two categories: rangebased and range-free. In addition, we analyze the architectures of UASNs based on different applications, and compare their performances from the aspects of communication cost, accuracy, coverage and so on. Open research issues which would affect the accuracy of localization are also discussed, including MAC protocols, sound speed and time synchronization.展开更多
This paper considers an underwater acoustic sensor network with one mobile surface node to collect data from multiple underwater nodes,where the mobile destination requests retransmission from each underwater node ind...This paper considers an underwater acoustic sensor network with one mobile surface node to collect data from multiple underwater nodes,where the mobile destination requests retransmission from each underwater node individually employing traditional automatic-repeat-request(ARQ) protocol.We propose a practical node cooperation(NC) protocol to enhance the collection efficiency,utilizing the fact that underwater nodes can overhear the transmission of others.To reduce the source level of underwater nodes,the underwater data collection area is divided into several sub-zones,and in each sub-zone,the mobile surface node adopting the NC protocol could switch adaptively between selective relay cooperation(SRC) and dynamic network coded cooperation(DNC) .The difference of SRC and DNC lies in whether or not the selected relay node combines the local data and the data overheard from undecoded node(s) to form network coded packets in the retransmission phase.The NC protocol could also be applied across the sub-zones due to the wiretap property.In addition,we investigate the effects of different mobile collection paths,collection area division and cooperative zone design for energy saving.The numerical results showthat the proposed NC protocol can effectively save energy compared with the traditional ARQ scheme.展开更多
As each cluster head(CH)sensor node is used to aggregate,fuse,and forward data from different sensor nodes in an underwater acoustic sensor network(UASN),guaranteeing the data security in a CH is very critical.In this...As each cluster head(CH)sensor node is used to aggregate,fuse,and forward data from different sensor nodes in an underwater acoustic sensor network(UASN),guaranteeing the data security in a CH is very critical.In this paper,a cooperative security monitoring mechanism aided by multiple slave cluster heads(SCHs)is proposed to keep track of the data security of a CH.By designing a low complexity“equilateral triangle algorithm(ETA)”,the optimal SCHs(named as ETA-based multiple SCHs)are selected from the candidate SCHs so as to improve the dispersion and coverage of SCHs and achieve largescale data security monitoring.In addition,by analyzing the entire monitoring process,the close form expression of the probability of the failure attack identification for the SCHs with respect to the probability of attack launched by ordinary nodes is deduced.The simulation results show that the proposed optimal ETA-based multiple SCH cooperation scheme has lower probability of the failure attack identification than that of the existing schemes.In addition,the numerical simulation results are consistent with the theoretical analysis results,thus verifying the effectiveness of the proposed scheme.展开更多
Due to the characteristics of the underwater acoustic channel, such as long propagation delay and low available bandwidth, the media access control (MAC) protocol designed for underwater acoustic sensor networks (UWAS...Due to the characteristics of the underwater acoustic channel, such as long propagation delay and low available bandwidth, the media access control (MAC) protocol designed for underwater acoustic sensor networks (UWASNs) is quite different from that for terrestrial wireless sensor networks. In this paper, we propose a MAC protocol for the UWASNs, named the funneling MAC (FMAC-U), which is a contention-based MAC protocol with a three-way handshake. The FMAC-U protocol uses an improved three-way handshake mechanism and code division multiple access (CDMA) based technology for request-to-send (RTS) signals transmitting to the sink in order that the sink can receive packets from multiple neighbors in a fixed order during each round of handshakes. The mechanism reduces the packet collisions and alleviates the funneling effect, especially alleviating the choke point of the UWASNs. Simulation results show that the proposed FMAC-U protocol achieves higher throughput, smaller packet drop ratio, lower end-to-end delay, and lower overhead of the control packet compared to the existing MAC protocols for UWASNs.展开更多
Distributed underwater acoustic sensor networks(UASNs)are envisioned in real-time ocean current velocity estimation.However,UASNs at present are still dominated by post-processing partially due to the complexity of on...Distributed underwater acoustic sensor networks(UASNs)are envisioned in real-time ocean current velocity estimation.However,UASNs at present are still dominated by post-processing partially due to the complexity of on-line detection for travel times and lack of dedicated medium access control(MAC)protocols.In this study,we propose a dedicated MAC protocol package for real-time ocean current velocity estimation using distributed UASNs.First,we introduce the process and requirements of ocean current velocity estimation.Then,we present a series of spatial reuse time division multiple access(TDMA)protocols for each phase of real-time ocean current field estimation using distributed UASNs,followed by numerical analysis.We divide UASNs into two categories according to their computing ability:feature-complete and feature-incomplete systems.The feature-complete systems that have abundant computing ability carry out the presented MAC protocol package in three phases,whereas the feature-incomplete ones do not have enough computing ability and the presented MAC protocol package is reduced to two phases plus an additional downloading phase.Numerical analysis shows that feature-complete systems using mini-slot TDMA have the best real-time performance,in comparison with feature-incomplete systems and other feature-complete counterparts.Feature-incomplete systems are more energy-saving than feature-complete ones,owing to the absence of in-network data exchange.展开更多
In the underwater medium,the speed of sound varies with water depth,temperature,and salinity.The inhomogeneity of water leads to bending of sound rays,making the existing localization algorithms based on straightline ...In the underwater medium,the speed of sound varies with water depth,temperature,and salinity.The inhomogeneity of water leads to bending of sound rays,making the existing localization algorithms based on straightline propagation less precise.To realize high-precision node positioning in underwater acoustic sensor networks(UASNs),a multi-layer isogradient sound speed profile(SSP)model is developed using the linear segmentation approximation approach.Then,the sound ray tracking problem is converted into a polynomial root-searching problem.Based on the derived gradient of the signal’s Doppler shift at the sensor node,a novel underwater node localization algorithm is proposed using both the time difference of arrival(TDOA)and frequency difference of arrival(FDOA).Simulations are implemented to illustrate the effectiveness of the proposed algorithm.Compared with the traditional straight-line propagation method,the proposed algorithm can effectively handle the sound ray bending phenomenon.Estimation accuracy with different SSP modeling errors is also investigated.Overall,accurate and reliable node localization can be achieved.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant 62171187the Guangdong Basic and Applied Basic Research Foundation under Grant 2022A1515011476+1 种基金the Science and Technology Program of Guangzhou under Grant 201904010373the Key Program of Marine Economy Development (Six Marine Industries) Special Foundation of Department of Natural Resources of Guangdong Province (GDNRC [2020]009)。
文摘Wireless information and power transfer(WIPT) enables simultaneously communications and sustainable power supplement without the erection of power supply lines and the replacement operation of the batteries for the terminals. The application of WIPT to the underwater acoustic sensor networks(UWASNs) not only retains the long range communication capabilities, but also provides an auxiliary and convenient energy supplement way for the terminal sensors, and thus is a promising scheme to solve the energy-limited problem for the UWASNs. In this paper, we propose the integration of WIPT into the UWASNs and provide an overview on various enabling techniques for the WIPT based UWASNs(WIPT-UWASNs) as well as pointing out future research challenges and opportunities for WIPT-UWASNs.
基金supported by the National Natural Science Foundation of China(Nos.61374021,61222310,and 61328302)the Zhejiang Provincial Natural Science Foundation of China(No.LZ14F030003)+3 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China(Nos.20130101110109 and 20120101110115)the Zhejiang Provincial Science and Technology Planning Projects of China(No.2012C21044)the Marine Interdisciplinary Research Guiding Funds for Zhejiang University(No.2012HY009B)the Fundamental Research Funds for the Central Universities,China(No.2014XZZX003-12)
文摘Long propagation delay, limited bandwidth, and high bit error rate pose great challenges in media access control （MAC） protocol design for underwater acoustic networks. A MAC protocol called slotted floor acquisition multiple access （slotted-FAMA） suitable for underwater acoustic networks is proposed and analyzed. This FAMA based protocol adds a time slot mechanism to avoid DATA packet collisions. However, slotted-FAMA is not suitable for dense networks since the multiple request-to-send （RTS） attempts problem in dense networks is serious and greatly limits the network throughput. To overcome this drawback, this paper proposes a slotted-FAMA based MAC protocol for underwater acoustic networks, called RC-SFAMA. RC-SFAMA introduces an RTS competition mechanism to keep the network from high frequency of backoff caused by the multiple RTS attempts problem. Via the RTS competition mechanism, useful data transmission can be completed successfully when the situation of multiple RTS attempts occurs. Simulation results show that RC-SFAMA increases the network throughput efficiency as compared with slotted-FAMA, and minimizes the energy consumption.
基金This work was supported by National Basic Research Program of China(No.2018YFC1405904).
文摘Since mobile nodes such as autonomous underwater vehicles can effectively expand network coverage,underwater acoustic networks with mobile nodes have attracted more and more attention in recent years.To ensure the timely access of a mobile node without disturbing the normal transmission of data packets from static nodes,a sequence-scheduled and query-based medium access control protocol is proposed in this paper.The underwater nodes with data packets to be transmitted reply with a control packet for channel reservation after receiving the broadcast control packet of the buoy,then the reserved nodes transmit their data packets as the order calculated by the buoy.We develop a mechanism to adjust the transmission order of the control packets sent by the underwater nodes in the handshake phase to reduce the collision and guarantee the success rate of reservation,and a query is initiated when the reserved control packet of the mobile node is not received by the buoy in the handshake to respond to the data transmission request of the mobile node in time.Simulations show that the maximum nodal throughput of the proposed MAC protocol increases by at least 20%and the access delay of the mobile node decreases by about 90%,compared to the two reference protocols.Besides,the average access probability of the mobile node in the proposed protocol is more than 90%.
基金supported in part by the Key Laboratory of IoT of Qinghai under Grant 2022‐ZJ‐Y21in part by the National Natural Science Foundation of China under Grant No.61962052.
文摘Zeroing neurodynamics methodology,which dedicates to finding equilibrium points of equations,has been proven to be a powerful tool in the online solving of problems with considerable complexity.In this paper,a method for underwater acoustic sensor network(UASN)localisation is proposed based on zeroing neurodynamics methodology to preferably locate moving underwater nodes.A zeroing neurodynamics model specifically designed for UASN localisation is constructed with rigorous theoretical analyses of its effectiveness.The proposed zeroing neurodynamics model is compatible with some localisation algorithms,which can be utilised to eliminate error in non‐ideal situations,thus further improving its effectiveness.Finally,the effectiveness and compatibility of the proposed zeroing neurodynamics model are substantiated by examples and computer simulations.
基金supported in part by the National Natural Science Foundation of China under Grant 62171405in part by the National Science Fund for Distinguished Young Scholars under Grant 62225114
文摘With the increasing demand for marine exploration, underwater acoustic sensor networks (UASNs) are prone to have the characteristics of large-scale, long term monitoring, and high data traffic load. Underwater media access control (MAC) protocols, which allow multiple users to share the common medium fairly and efficiently, are essential for the performance of UASNs. However, the design of MAC protocols is confronted with the challenges of spatial unfairness, data eruption, and low energy efficiency. In this paper, we propose a novel data concurrent transmission (DCT) MAC protocol, which is able to exploit long propagation delay and conduct concurrent transmission. Specifically, we present the theoretical performance analysis of the proposed MAC protocol in detail and give an analytical solution of the success concurrent transmission probability between nodes. In addition, simulation results are provided to demonstrate that our proposed protocol is appropriate for UASNs and can significantly improve the performance in terms of network throughput and energy consumption. Finally, we give some typical future applications of UASNs and discuss the demands on MAC protocol design.
基金This work was supported by the National Key Research and Development Program of China(No.2018YFC0308500)National Natural Science Foundation of China(Nos.61901273,11774074,61771152,U1806201 and 11974090)+1 种基金Natural Science Foundation of Heilongjiang Province of China(No.YQ2019F002)Acoustic Science and Technology Laboratory,Science and Technology on Underwater Information and Control Laboratory,and by the Young Elite Scientists Sponsorship by CAST.
文摘Traditional underwater acoustic communication networks(UACNs)generally use omnidirectional transmission technology that causes a large number of data-packet collisions,thus resulting in low network throughput and high end-to-end delays.Compared with omnidirectional transmission technology,directional technology only sends and receives data packets in a specified direction.This can significantly reduce the probability of collisions and improve network performance.However,it also causes a deafness problem,which occurs when the sending node sends a data packet to the receiving node but the receiving node is unable to reply to the sender,because its antenna beam is closed.To resolve this issue,this study proposes a collision classification media access control(CC-MAC)protocol for UACNs.With this protocol,the underwater acoustic channel is divided into two subchannels,and the nodes transmit corresponding data types on them.The sending node can estimate the current status of the receiving node(i.e.,no collision,normal collision,deafness)according to the type of the data packet received and the sub-channel it arrived on,and it can choose correct options to improve network efficiency.Finally,we verify the performance of CC-MAC via simulations,showing that the protocol achieved higher network throughput and lower end-toend delays.
基金Supported by the National Natural Science Foundation of China under Grant No.62171310the Marine Defense Innovation Fund JJ-2020-701-09Lanzhou Jiaotong University-Tianjin University Co-Funding under Grant No.2022064。
文摘Cooperative jamming(CJ)is one of the important methods to solve security problems of underwater acoustic sensor networks(UASNs).In this paper,we propose a Cooperative Jamming Scheme based on Node Authentication for UASNs to improve the effect of CJ by selecting suitable jamming source for found illegal nodes.In the node authentication,all nodes will be identified by their trust value(TV).TV is calculated according to three types of evidence:channel-based trust evidence,behavior-based trust evidence and energy-based trust evidence.Besides,to deal with cases where legal nodes may be suspected,the historical TV and trust redemption will be considered when calculating TV.In cooperative jamming,according to the link quality,several nodes are selected to jam illegal nodes.Both simulation and field experiment show that the proposed scheme can accurately find the illegal nodes in the time-vary channel and improve the security of the network.
基金supported by National Natural Science Foundation of China under Grants 61001067,61371093and 61172105Natural Science Foundation of Zhejiang Prov.China under Grants LY13D060001
文摘Underwater Acoustic Sensor Network(UASN) has attracted significant attention because of its great influence on ocean exploration and monitoring. On account of the unique characteristics of underwater environment, localization, as one of the fundamental tasks in UASNs, is a more challenging work than in terrestrial sensor networks. A survey of the ranging algorithms and the network architectures varied with different applications in UASNs is provided in this paper. Algorithms used to estimate the coordinates of the UASNs nodes are classified into two categories: rangebased and range-free. In addition, we analyze the architectures of UASNs based on different applications, and compare their performances from the aspects of communication cost, accuracy, coverage and so on. Open research issues which would affect the accuracy of localization are also discussed, including MAC protocols, sound speed and time synchronization.
基金supported in part by National Key Research and Development Program of China under Grants No.2016YFC1400200 and 2016YFC1400204National Natural Science Foundation of China under Grants No.41476026,41676024 and 41376040Fundamental Research Funds for the Central Universities of China under Grant No.220720140506
文摘This paper considers an underwater acoustic sensor network with one mobile surface node to collect data from multiple underwater nodes,where the mobile destination requests retransmission from each underwater node individually employing traditional automatic-repeat-request(ARQ) protocol.We propose a practical node cooperation(NC) protocol to enhance the collection efficiency,utilizing the fact that underwater nodes can overhear the transmission of others.To reduce the source level of underwater nodes,the underwater data collection area is divided into several sub-zones,and in each sub-zone,the mobile surface node adopting the NC protocol could switch adaptively between selective relay cooperation(SRC) and dynamic network coded cooperation(DNC) .The difference of SRC and DNC lies in whether or not the selected relay node combines the local data and the data overheard from undecoded node(s) to form network coded packets in the retransmission phase.The NC protocol could also be applied across the sub-zones due to the wiretap property.In addition,we investigate the effects of different mobile collection paths,collection area division and cooperative zone design for energy saving.The numerical results showthat the proposed NC protocol can effectively save energy compared with the traditional ARQ scheme.
基金supported in part by the Joint Fund of Science and Technology Department of Liaoning Province and State Key Laboratory of Robotics,China under Grant 2021-KF-22-08in part by the Basic Research Program of Science and Technology of Shenzhen,China under Grant JCYJ20190809161805508in part by the National Natural Science Foundation of China under Grant 62271423 and Grant 41976178.
文摘As each cluster head(CH)sensor node is used to aggregate,fuse,and forward data from different sensor nodes in an underwater acoustic sensor network(UASN),guaranteeing the data security in a CH is very critical.In this paper,a cooperative security monitoring mechanism aided by multiple slave cluster heads(SCHs)is proposed to keep track of the data security of a CH.By designing a low complexity“equilateral triangle algorithm(ETA)”,the optimal SCHs(named as ETA-based multiple SCHs)are selected from the candidate SCHs so as to improve the dispersion and coverage of SCHs and achieve largescale data security monitoring.In addition,by analyzing the entire monitoring process,the close form expression of the probability of the failure attack identification for the SCHs with respect to the probability of attack launched by ordinary nodes is deduced.The simulation results show that the proposed optimal ETA-based multiple SCH cooperation scheme has lower probability of the failure attack identification than that of the existing schemes.In addition,the numerical simulation results are consistent with the theoretical analysis results,thus verifying the effectiveness of the proposed scheme.
基金(No. 2009AA093601-3) supported by the National High-Tech R & D Program (863) of China
文摘Due to the characteristics of the underwater acoustic channel, such as long propagation delay and low available bandwidth, the media access control (MAC) protocol designed for underwater acoustic sensor networks (UWASNs) is quite different from that for terrestrial wireless sensor networks. In this paper, we propose a MAC protocol for the UWASNs, named the funneling MAC (FMAC-U), which is a contention-based MAC protocol with a three-way handshake. The FMAC-U protocol uses an improved three-way handshake mechanism and code division multiple access (CDMA) based technology for request-to-send (RTS) signals transmitting to the sink in order that the sink can receive packets from multiple neighbors in a fixed order during each round of handshakes. The mechanism reduces the packet collisions and alleviates the funneling effect, especially alleviating the choke point of the UWASNs. Simulation results show that the proposed FMAC-U protocol achieves higher throughput, smaller packet drop ratio, lower end-to-end delay, and lower overhead of the control packet compared to the existing MAC protocols for UWASNs.
基金This work was supported by the National Natural Science Foundation of China(No.61531017)the Science and Technology Bureau of Zhoushan(No.2018C41029)the Science and Technology Department of Zhejiang Province(Nos.2018R52046 and LGG18F010005).
文摘Distributed underwater acoustic sensor networks(UASNs)are envisioned in real-time ocean current velocity estimation.However,UASNs at present are still dominated by post-processing partially due to the complexity of on-line detection for travel times and lack of dedicated medium access control(MAC)protocols.In this study,we propose a dedicated MAC protocol package for real-time ocean current velocity estimation using distributed UASNs.First,we introduce the process and requirements of ocean current velocity estimation.Then,we present a series of spatial reuse time division multiple access(TDMA)protocols for each phase of real-time ocean current field estimation using distributed UASNs,followed by numerical analysis.We divide UASNs into two categories according to their computing ability:feature-complete and feature-incomplete systems.The feature-complete systems that have abundant computing ability carry out the presented MAC protocol package in three phases,whereas the feature-incomplete ones do not have enough computing ability and the presented MAC protocol package is reduced to two phases plus an additional downloading phase.Numerical analysis shows that feature-complete systems using mini-slot TDMA have the best real-time performance,in comparison with feature-incomplete systems and other feature-complete counterparts.Feature-incomplete systems are more energy-saving than feature-complete ones,owing to the absence of in-network data exchange.
基金Project supported by the National Key Research and Development Program of China(No.2017YFC0305900)the Zhejiang University K.P.Chao’s High Technology Development Foundation(No.2020ZL013)。
文摘In the underwater medium,the speed of sound varies with water depth,temperature,and salinity.The inhomogeneity of water leads to bending of sound rays,making the existing localization algorithms based on straightline propagation less precise.To realize high-precision node positioning in underwater acoustic sensor networks(UASNs),a multi-layer isogradient sound speed profile(SSP)model is developed using the linear segmentation approximation approach.Then,the sound ray tracking problem is converted into a polynomial root-searching problem.Based on the derived gradient of the signal’s Doppler shift at the sensor node,a novel underwater node localization algorithm is proposed using both the time difference of arrival(TDOA)and frequency difference of arrival(FDOA).Simulations are implemented to illustrate the effectiveness of the proposed algorithm.Compared with the traditional straight-line propagation method,the proposed algorithm can effectively handle the sound ray bending phenomenon.Estimation accuracy with different SSP modeling errors is also investigated.Overall,accurate and reliable node localization can be achieved.
