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UNDERWATER ACUSTIC SENSOR NETWORKS (UW-ASNs). Daladier Jabba Molinares Department of Computer Science and Engineering University of South Florida Tampa, FL 33620 daladier@cse.usf.edu. UNDERWATER ACUSTIC SENSOR NETWORKS (UW-ASNs). Introduction Communication architecture

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underwater acustic sensor networks uw asns

UNDERWATER ACUSTIC SENSOR NETWORKS (UW-ASNs)

Daladier Jabba Molinares

Department of Computer Science and Engineering

University of South Florida

Tampa, FL 33620

daladier@cse.usf.edu

underwater acustic sensor networks uw asns1
UNDERWATER ACUSTIC SENSOR NETWORKS (UW-ASNs)
  • Introduction
  • Communication architecture
  • UW-ASN: Design challenges
  • Principal layers
    • MAC Layer
    • Network Layer
    • Transport Layer
  • Clusters in Mobile Ad hoc Networks
  • Minimum Cut problem applied to UW-ASN
  • References
  • Questions
introduction1
INTRODUCTION
  • Group of sensors and vehicles deployed underwater and networked via acoustic links, performing collaborative tasks
  • Equipment
    • Autonomous Underwater Vehicles (AUVs)
    • Underwater sensors (UW-ASN)
introduction cont
INTRODUCTION (Cont…)
  • Objectives
    • UW_ASNs
      • To exploit multi hop paths
      • To minimize the signaling overhead for building underwater paths
    • AUVs
      • Rely on local intelligence
      • Less dependent on communications from online shores
      • Control strategies (autonomous coordination obstacle avoidance)
introduction cont1
INTRODUCTION (Cont…)
  • Applications
    • Environment monitoring
      • Review how human activities affect the marine ecosystem
    • Undersea explorations
      • Detect underwater oilfields
    • Disaster prevention
      • Monitoring ocean currents and winds (Tsunamis)
    • Assisted navigation
      • Locate dangerous rocks in shallow waters
    • Distributed tactical surveillance
      • Intrusion detection (Navy)
introduction cont2
INTRODUCTION (Cont…)
  • Acoustic comms  physical layer technology in underwater networks
  • High attenuation  radio waves propagation problems
  • Links for underwater networks based on acoustic wireless communications (typically used)
introduction cont3
INTRODUCTION (Cont…)
  • Challenges
    • Available bandwidth is limited
    • Propagation delayUnderwater=5 x Radio Frequency(RF)ground
    • High bit errors and temporary loss of connectivity
    • Limited battery power
    • Tendency of failure in the underwater sensors because of corrosion
comms architecture1
COMMS ARCHITECTURE
  • Two-dimensional Underwater Sensor Networks : for ocean bottom monitoring
  • Three-dimensional Underwater Sensor Networks : for ocean-column monitoring
  • Sensor Networks with Autonomous Underwater vehicles : for underwater explorations
comms architecture cont
COMMS ARCHITECTURE (Cont…)

1. Static two-dimensional UW-ASNs for ocean bottom monitoring

  • Components:

Gateway

*: not necessary

comms architecture cont1
COMMS ARCHITECTURE (Cont…)

Satellite comms

RF comms

Comms with the surface station

Acoustic link comms

Comms. Intra clusters (using CH)

anchored

slide13
Static two-dimensional UW-ASNs for ocean

bottom monitoring (Cont…)

  • Problems
    • Long distances between gateways and UW-ASNs
      • Power to transmit decay easy
      • It is better multi hop paths
    • Bandwidth limitations
      • Greater bandwidth for a shorter transmission distance
    • Increasing the UW-ASNs density generates routing complexity
  • Solving the problems
    • Energy savings
    • Increase network capacity
comms architecture cont2
COMMS ARCHITECTURE (Cont…)

2. Three-dimensional Underwater Sensor

Networks

  • Components:

*: not necessary

comms architecture cont3
COMMS ARCHITECTURE (Cont…)

Satellite comms

RF comms

Comms with the surface station

Acoustic link comms

anchored

slide16
Three-dimensional Underwater Sensor

Networks (Cont…)

  • Problems
    • If they are attached to a surface buoy
      • They can be easily detected by enemies
      • Floating buoys are vulnerable to the weather and pilfering
      • ship navigations can be a problem
    • Increasing the UW-ASNs density generates routing complexity
  • Solving the problems
    • Be anchored to the bottom of the ocean (to an anchors by wires)
    • Energy savings
    • Increase network capacity
comms architecture cont4
COMMS ARCHITECTURE (Cont…)

3. Sensor Networks with Autonomous

Underwater vehicles

  • Components:

AUV

*: not necessary

comms architecture cont5
COMMS ARCHITECTURE (Cont…)

Satellite comms

RF comms

Comms with the surface station

Acoustic link comms

anchored

design challenges cont
DESIGN CHALLENGES (Cont…)
  • UWSNs vs Terrestrial Sensor Networks
    • Cost
      • Terrestrial sensor networks will be cheaper and cheaper with the time
      • UWSNs are expensive
    • Deployment
      • Terrestrial SNs are densely deployed
      • UWSNs are generally more sparse
    • Power
      • For UWSNs is higher
    • Memory
      • Terrestrial sensors have less capacity
design challenges cont1
DESIGN CHALLENGES (Cont…)
  • Basics of acoustic propagation in UWSNs
    • Radio waves propagation for long distances through sea water only at frequencies of 30-300 Hz
      • High transmission power
      • Large antennas
    • Poor available Bandwidth

* In 802.11b : between 2.412 GHz to 2.484 GHz

design challenges cont2
DESIGN CHALLENGES (Cont…)
  • Some factors that affect the design
    • Path loss
      • Attenuation provoked by absorption due to conversion of acoustic energy into heat
      • Because of the spreading sound energy as a result of the expansion of the wavefronts
    • Noise
      • Man-made noise
      • Ambient noise
    • High delay
      • Propagation delayUnderwater=5 x Radio Frequency(RF)ground
medium access control layer
MEDIUM ACCESS CONTROL LAYER

Biomimetic Underwater Robot, Robolobster

mac layer cont
MAC LAYER (Cont…)
  • Multiple access techniques
    • Code Division Multiple Access (CDMA)
    • Carrier Sense Multiple Access (CSMA)
    • Time Division Multiple Access (TDMA)
    • Frequency Division Multiple Access (FDMA)
mac layer cont1
MAC LAYER (Cont…)
  • Proposed MAC protocols
    • Slotted Fama
      • Applies control packets before starting transmission to avoid multiple transmissions at the same time
      • Issue: handshaking process can generate low throughput
mac layer cont2
MAC LAYER (Cont…)
  • Adapted MACA to underwater acoustic networks
    • It uses CTS-RTS-DATA exchange and for Error detection STOP and WAIT ARQ
    • Retransmitting packets because of timeout in receiving ACK
    • The source drops the communication after K trials
  • Problems
  • Energy consumption because of repeating RTS several times before receiving a CTS
  • Deadlock problems
  • Solutions
  • To add a WAIT commands (destination tells that is busy)
  • Add an assignment priority to every packet
mac layer cont3
MAC LAYER (Cont…)
  • Clustering and CDMA/TDMA multiple access
    • For distributed UW-ASNs
    • Communication intra cluster uses TDMA (time slots)
    • CDMA by each cluster using a different code for transmission
    • Problem
      • Number of code is limited
    • Solution proposed
      • Reusable code (possible because the acoustic signal fades due to distance)
mac layer cont4
MAC LAYER (Cont…)
  • Open research issues
    • Design access codes for CDMA taking into account minimum interference among nodes
    • Maximize the channel utilization
    • Distributed protocols to save battery consumption
network layer cont
NETWORK LAYER (Cont…)
  • Proactive routing protocols
    • Dynamic Destination Sequenced Distance Vector (DSDV), Optimizing Link State Routing (OLSR)
    • They are not suitable for UW-ASNs
      • Large signaling overhead every time network topology has to be updated
      • All nodes are able to establish a path with others and it is not necessary
network layer cont1
NETWORK LAYER (Cont…)
  • Reactive routing protocols
    • Ad hoc On Demand Distance Vector (AODV) and Dynamic Source Routing (DSR)
    • They are not suitable for UW-ASNs
      • It requires flooding of control packets at the beginning to establish paths (excessive signaling overhead)
      • High latency on establishment of paths
      • Must of the reactive protocols rely in symmetrical links
network layer cont2
NETWORK LAYER (Cont…)
  • Geographical routing protocols
    • Routing with Guaranteed Delivery in Ad Hoc Wireless Networks (GFG) and Optimal local topology knowledge for energy efficient geographical routing in sensor networks (PTKF)
    • Establish source destination paths by leveraginglocalization information
      • A node selects its next hop based on the position of its neighbors and of the destination node
    • Problems
      • They work with GPS (GPS uses waves in the 1.5 GHz band)
      • It has not been improved the localization information in the underwater environment
network layer cont3
NETWORK LAYER (Cont…)
  • Solution proposed
    • Network layer protocols specifically tailored to underwater environment
    • Example
      • A routing protocol was proposed that autonomously establishes the underwater network topology, control network resources and establishes the network flows using a centralized management
network layer cont4
NETWORK LAYER (Cont…)
  • Open research issues
    • Develop algorithms that reduces the latency
    • Handle loss of connectivity using mechanisms without generating retransmission
    • Algorithms and protocols needs to improve the way to deal with disconnections because of failures of battery depletion
    • How to integrate AUV with UW-ASNs and able communication among them
transport layer cont
TRANSPORT LAYER (Cont…)
  • Unexplored area
  • It has to perform:
    • Flow control
      • To avoid that network devices with limited memory are overwhelmed by data transmissions
    • Congestion control
      • To prevent the network being congested
  • TCP implementations are not suited
    • The long Round Trip Time (RTT) in underwater environment affect the throughput
transport layer cont1
TRANSPORT LAYER (Cont…)
  • A transport layer for UW-ASNs requieres:
    • Reliability hop by hop
    • In case of congestion, transport layer need to be adapted faster to decrease the response time
    • Minimum energy consumption
    • To avoid many feedbacks with the ACK mechanism that can utilize bandwidth unnecessarily
transport layer cont2
TRANSPORT LAYER (Cont…)
  • Open research issues
    • Flow control strategies to reduce not only the high delay but also delay variance of the control messages
    • Efficient mechanisms to find the cause of packet loss
    • To create solutions for handling the effect of losses of connectivity caused by shadow zones
clusters in mobile ad hoc networks cont
Clusters in Mobile Ad hoc Networks (Cont…)
  • Reduce the overhead in the network
  • Reduce power consumption
  • Different type of nodes
    • Cluster head
    • Gateway
    • Nodes in the cluster
  • Communication
    • Intra cluster
    • Inter cluster
clusters in mobile ad hoc networks cont1
Clusters in Mobile Ad hoc Networks (Cont…)
  • Problems
    • Hidden Terminal problem
    • Exposed Terminal problem
clusters in mobile ad hoc networks cont2
Clusters in Mobile Ad hoc Networks (Cont…)
  • Topology control (Cluster Initialization)
    • LIDCA algorithm
      • lowest identifier
    • HCCA algorithm
      • high connectivity
    • Minimum cut problem (graph theory)
      • Contract nodes
  • Routing protocols
  • Maintenance
challenge

c

b

a

a

x

c

b

x

b,c

e

d

f

e

d

f

a

x

D,e,f

b,c

X,a,b,c

e

f

d

Connectivity

Challenge
  • Minimum Cut problem applied to UW-ASN (Network layer)
    • To reduce interference
references
References
  • I. F. Akyildiz, D. Pompili, and T. Melodia. Underwater Acoustic Sensor Networks: Research Challenges. Ad Hoc Networks (Elsevier), vol. 3(3), pp. 257–279, May 2005.
  • K. Kredo and P. Mohapatra. Medium Access Control in Wireless Sensor Networks. to appear in Computer Networks (Elsevier), 2006.
  • F. Salva-Garau and M. Stojanovic. Multi-cluster Protocol for Ad Hoc Mobile Underwater Acoustic Networks. In Proc. Of MTS/IEEE OCEANS. San Francisco, CA, Sep. 2003.
  • Hayat DOUKKALI and Loutfi NUAYMI. Analysis of MAC protocols for Underwater Acoustic Data Networks. 0-7803-8887-9/05. (c)2005 IEEE
  • Jim Partan, Jim Kurose Brian Neil Levine. A Survey of Practical Issues in Underwater Networks.
  • Borja Peleato and Milica Stojanovic. A MAC Protocol for Ad Hoc Underwater Acoustic Sensor Networks. WUWNet’06, September 25, 2006.
  • Ian F. Akyildiz, Dario Pompili, and Tommaso Melodia. State of the Art In Protocol Research for Underwater Acoustic Sensor Networks. WUWNet’06, September 25, 2006.
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