Results 1 - 10
of
315
the relationship between capacity and distance in an underwater acoustic communication channel
- ACM SIGMOBILE Mobile Computing and Communications Review (MC2R), vol.11, Issue
, 2007
"... Path loss of an underwater acoustic communication channel depends not only on the transmission distance, but also on the signal frequency. As a result, the useful bandwidth depends on the transmission distance, a feature that distinguishes an underwater acoustic system from a terrestrial radio one. ..."
Abstract
-
Cited by 165 (37 self)
- Add to MetaCart
(Show Context)
Path loss of an underwater acoustic communication channel depends not only on the transmission distance, but also on the signal frequency. As a result, the useful bandwidth depends on the transmission distance, a feature that distinguishes an underwater acoustic system from a terrestrial radio one. This fact influences the design of an acoustic network: a greater information throughput is available if messages are relayed over multiple short hops instead of being transmitted directly over one long hop. We asses the bandwidth dependency on the distance using an analytical method that takes into account physical models of acoustic propagation loss and ambient noise. A simple, single-path time-invariant model is considered as a first step. To assess the fundamental bandwidth limitation, we take an information-theoretic approach and define the bandwidth corresponding to optimal signal energy allocation – one that maximizes the channel capacity subject to the constraint that the transmission power is finite. Numerical evaluation quantifies the bandwidth and the channel capacity, as well as the transmission power needed to achieve a pre-specified SNR threshold, as functions of distance. These results lead to closed-form approximations, which may become useful tools in the design and analysis of acoustic networks. I.
A Survey of Practical Issues in Underwater Networks
- In Proc. ACM WUWNet
, 2006
"... ..."
(Show Context)
Routing Algorithms for Delay-insensitive and Delay-sensitive Applications in Underwater Sensor Networks
- In Proc. of ACM Conference on Mobile Computing and Networking (MobiCom
, 2006
"... Underwater sensor networks consist of sensors and vehicles deployed to perform collaborative monitoring tasks over a given region. Underwater sensor networks will find applications in oceanographic data collection, pollution monitoring, offshore exploration, disaster prevention, assisted navigation, ..."
Abstract
-
Cited by 70 (10 self)
- Add to MetaCart
(Show Context)
Underwater sensor networks consist of sensors and vehicles deployed to perform collaborative monitoring tasks over a given region. Underwater sensor networks will find applications in oceanographic data collection, pollution monitoring, offshore exploration, disaster prevention, assisted navigation, tactical surveillance, and mine reconnaissance. Underwater acoustic networking is the enabling technology for these applications. In this paper, an architecture for three-dimensional underwater sensor networks is considered, and a model characterizing the acoustic channel utilization efficiency is introduced, which allows investigating some fundamental characteristics of the underwater environment. In particular, the model allows setting the optimal packet size for underwater communications given monitored volume, density of the sensor network, and application requirements. Moreover, the problem of data gathering is investigated at the network layer by considering the cross-layer interactions between the routing functions and the characteristics of the underwater acoustic channel. Two distributed routing algorithms are introduced for delay-insensitive and delaysensitive applications. The proposed solutions allow each node to select its next hop, with the objective of minimizing the energy consumption taking the varying condition of the underwater channel and the different application requirements into account. The proposed routing solutions are shown to achieve the performance targets by means of simulation.
Time synchronization for high latency acoustic networks
- In Proc. IEEE InfoCom
, 2006
"... Abstract — Distributed time synchronization is an important part of a sensor network where sensing and actuation must be coordinated across multiple nodes. Several time synchronization protocol that maximize accuracy and energy conservation have been developed, including FTSP, TPSN, and RBS. All of ..."
Abstract
-
Cited by 68 (10 self)
- Add to MetaCart
(Show Context)
Abstract — Distributed time synchronization is an important part of a sensor network where sensing and actuation must be coordinated across multiple nodes. Several time synchronization protocol that maximize accuracy and energy conservation have been developed, including FTSP, TPSN, and RBS. All of these assume nearly instantaneous wireless communication between sensor nodes; each of them work well in today’s RF-based sensor networks. We are just beginning to explore underwater sensor networks where communication is primarily via acoustic telemetry. With acoustic communication, where the propagation speed is nearly five orders of magnitude slower than RF, assumptions about rapid communication are incorrect and new approaches to time synchronization are required. We present Time Synchronization for High Latency (TSHL), designed assuming such high latency propagation. We show through analysis and simulation that it achieves precise time synchronization with minimal energy cost. Although at very short distances existing protocols are adequate, TSHL shows twice the accuracy at 500m, demonstrating the need to model both clock skew and propagation latency. I.
Stochastic event capture using mobile sensors subject to a quality metric
- in Proc. of ACM MobiCom
, 2006
"... Mobile sensors cover more area over a period of time than the same number of stationary sensors. However, the quality of coverage achieved by mobile sensors depends on the velocity, mobility pattern, number of mobile sensors deployed and the dynamics of the phenomenon being sensed. The gains attaine ..."
Abstract
-
Cited by 57 (1 self)
- Add to MetaCart
(Show Context)
Mobile sensors cover more area over a period of time than the same number of stationary sensors. However, the quality of coverage achieved by mobile sensors depends on the velocity, mobility pattern, number of mobile sensors deployed and the dynamics of the phenomenon being sensed. The gains attained by mobile sensors over static sensors and the optimal motion strategies for mobile sensors are not well understood. In this paper we consider the problem of event capture using mobile sensors. The events of interest arrive at certain points in the sensor field and fade away according to arrival and departure time distributions. An event is said to be captured if it is sensed by one of the mobile sensors before it fades away. For this scenario we analyze how the quality of coverage scales with the velocity, path and number of mobile sensors. We characterize the cases where the deployment of mobile sensors has
T-Lohi: A new class of MAC protocols for underwater acoustic sensor networks
, 2007
"... Abstract—This paper introduces T-Lohi, a new class of distributed and energy-efficient media-access protocols (MAC) for underwater acoustic sensor networks (UWSN). MAC design for UWSN faces significant challenges. For example, acoustic communication suffers from latencies five orders-of-magnitude la ..."
Abstract
-
Cited by 43 (9 self)
- Add to MetaCart
(Show Context)
Abstract—This paper introduces T-Lohi, a new class of distributed and energy-efficient media-access protocols (MAC) for underwater acoustic sensor networks (UWSN). MAC design for UWSN faces significant challenges. For example, acoustic communication suffers from latencies five orders-of-magnitude larger than radio communication, so a naive CSMA MAC would require very long listen time resulting in low throughput and poor energy efficiency. In this paper, we first identify unique characteristics in underwater networking that may affect all MACs, such as space-time uncertainty and deafness conditions. We then develop T-Lohi employing a novel tone-based contention resolution mechanism that exploits space-time uncertainty and high latency to detect collisions and count contenders, achieving goodthroughputacrossallofferedloads.Lohiusesourlow-power wake-up receiver to significantly reduce energy consumption. Finally, we evaluate design choices and protocol performance through extensive simulation. The results show that the energy cost of packet transmission is within 3–9 % of optimal, and that Lohi achieves good channel utilization, within 30 % utilization of the theoretical maximum. We also show that Lohi is stable and fair under both low and very high offered loads. I.
State-of-the-art in protocol research for underwater acoustic sensor networks
- In Underwater Networks
, 2006
"... In this paper, architectures for two-dimensional and three-dimensional underwater sensor networks are discussed. A detailed overview on the current solutions for medium access control, network, and transport layer protocols are given and open research issues are discussed. Categories and Subject Des ..."
Abstract
-
Cited by 42 (0 self)
- Add to MetaCart
(Show Context)
In this paper, architectures for two-dimensional and three-dimensional underwater sensor networks are discussed. A detailed overview on the current solutions for medium access control, network, and transport layer protocols are given and open research issues are discussed. Categories and Subject Descriptors:
Akyildiz, “Deployment analysis in underwater acoustic wireless sensor networks,” in WUWNet ’06
- Proceedings of the first ACM international workshop on Under Water Networks. Los
"... In this paper, different deployment strategies for two-dimensional and three-dimensional communication architectures for UnderWater Acoustic Sensor Networks (UW-ASNs) are proposed, and statistical deployment analysis for both architectures is provided. The objectives of this paper are to determine t ..."
Abstract
-
Cited by 41 (1 self)
- Add to MetaCart
(Show Context)
In this paper, different deployment strategies for two-dimensional and three-dimensional communication architectures for UnderWater Acoustic Sensor Networks (UW-ASNs) are proposed, and statistical deployment analysis for both architectures is provided. The objectives of this paper are to determine the minimum number of sensors needed to be deployed to achieve the optimal sensing and communication coverage, which are dictated by the application; provide guidelines on how to choose the optimal deployment surface area, given a target region; study the robustness of the sensor network to node failures, and provide an estimate of the number of redundant sensors to be deployed to compensate for possible failures. Categories and Subject Descriptors:
On routing with guaranteed delivery in threedimensional ad hoc wireless networks
- In Proceedings of the International Conference on Distributed Computing and Networking, volume 4904 of Lecture Notes in Computer Science
, 2008
"... We study the problem of routing in three-dimensional ad hoc networks. We are interested in routing algorithms that guarantee delivery and are k-local, i.e., each intermediate node v’s routing decision only depends on knowledge of the labels of the source and destination nodes, of the subgraph induce ..."
Abstract
-
Cited by 40 (3 self)
- Add to MetaCart
(Show Context)
We study the problem of routing in three-dimensional ad hoc networks. We are interested in routing algorithms that guarantee delivery and are k-local, i.e., each intermediate node v’s routing decision only depends on knowledge of the labels of the source and destination nodes, of the subgraph induced by nodes within distance k of v, and of the neighbour of v from which the message was received. We model a threedimensional ad hoc network by a unit ball graph, where nodes are points in three-dimensional space, and for each node v, there is an edge between v and every node u contained in the unit-radius ball centred at v. The question of whether there is a simple local routing algorithm that guarantees delivery in unit ball graphs has been open for some time. In this paper, we answer this question in the negative: we show that for any fixed k, there can be no k-local routing algorithm that guarantees delivery on all unit ball graphs. This result is in contrast with the twodimensional case, where 1-local routing algorithms that guarantee delivery are known. Specifically, we show that guaranteed delivery is possible if the nodes of the unit ball graph are contained in a slab of thickness 1 / √ 2. However, there is no k-local routing algorithm that guarantees delivery for the class of unit ball graphs contained in thicker slabs, i.e., slabs of thickness 1 / √ 2+ɛ for some ɛ> 0. The algorithm for routing in thin slabs derives from a transformation of unit ball graphs contained in thin slabs into quasi unit
Underwater Localization in Sparse 3D Acoustic Sensor Networks
- in Proceedings of INFOCOM
, 2008
"... Abstract—We study the localization problem in sparse 3D underwater sensor networks. Considering the fact that depth information is typically available for underwater sensors, we transform the 3D underwater positioning problem into its twodimensional counterpart via a projection technique and prove t ..."
Abstract
-
Cited by 39 (3 self)
- Add to MetaCart
(Show Context)
Abstract—We study the localization problem in sparse 3D underwater sensor networks. Considering the fact that depth information is typically available for underwater sensors, we transform the 3D underwater positioning problem into its twodimensional counterpart via a projection technique and prove that a non-degenerative projection preserves network localizability. We further prove that given a network and a constant k, all of the geometric k-lateration localization methods are equivalent. Based on these results, we design a purely distributed localization framework termed USP. This framework can be applied with any ranging method proposed for 2D terrestrial sensor networks. Through theoretical analysis and extensive simulation, we show that USP preserves the localizability of the original 3D network via a simple projection and improves localization capabilities when bilateration is employed. USP has low storage and computation requirements, and predictable and balanced communication overhead. Index Terms—3D underwater localization, acoustic sensor networks, network localization problem, localizability. I.
