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Wireless Sensor networks survey and research challenges

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University of Tehran Dept. Electrical and Computer Engineering Wireless Sensor networks survey and research challenges Presented by Hosein Sabaghian-Bidgoli – PowerPoint PPT presentation

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Title: Wireless Sensor networks survey and research challenges


1
Wireless Sensor networkssurvey and research
challenges
University of Tehran Dept. Electrical and
Computer Engineering
  • Presented by
  • Hosein Sabaghian-Bidgoli
  • hsabaghianb_at_gmail.com
  • January 11, 2009

2
Outlines
  • Main references
  • Introduction
  • Definition
  • Communication Architecture
  • Protocol stack
  • WSN Characteristics
  • WSN Design factors
  • WSANs
  • WSN Structures
  • WSN Constraints
  • WSN Applications
  • WSN types
  • .

3
Outlines (cont.)
  • Task classification
  • Internal sensor system
  • Standard
  • Storage
  • Testbed
  • Diagnostic and debugging support
  • Network services
  • Localization
  • Synchronization
  • Coverage
  • Compression and aggregation
  • Security
  • Communication protocol
  • Transport
  • Network
  • Data link
  • Physical
  • Cross-layer
  • Conclusion

4
Main references
  • Ian F. Akyildiz, Weilian Su, Yogesh
    Sankarasubramaniam, and Erdal Cayirci, A Survey
    on Sensor Networks, IEEE Communications Magazine,
    August 2002
  • Ian F. Akyildiz, Ismail H. Kasimoglu, Wireless
    sensor and actor networks research challenges,
    Elsevier Ad Hoc Networks 2 (2004) 351367
  • Jennifer Yick, Biswanath Mukherjee, Dipak Ghosal,
    Wireless sensor network survey, Elsevier Computer
    Networks 52 (2008) 22922330

5
1
6
2
7
3
8
IntroductionWSN Definition
  • A sensor network is composed of a large number of
    sensor nodes that are densely deployed inside or
    very close to the phenomenon
  • random deployment
  • self-organizing capabilities

1
9
IntroductionWSN communication Architecture
1
10
IntroductionComponents of Sensor Node
1
11
IntroductionProtocol Stack
  • Protocols should be
  • Power aware
  • Location aware
  • Application aware

1
12
IntroductionWSN Characteristics
  • Major differences between sensor and ad-hoc
    network
  • Number of nodes is higher
  • Densely deployment
  • Sensor nodes are prone to failure.
  • Frequent topology changes
  • Broadcast communication paradigm
  • Limited processing and power capabilities.
  • Possible absence of unique global ID

1
13
IntroductionWSN Design Factors
  • Fault Tolerance
  • Scalability
  • Production Costs
  • Hardware Constraints
  • Sensor Network Topology
  • Environment
  • Transmission Media
  • Power Consumption

1
14
WSN Design Factors Fault Tolerance
  • Each Nodes are prone to unexpected failure (more
    than other network)
  • Fault tolerance is the ability to sustain sensor
    network functionalities without any interruption
    due to sensor node failures.

1
15
WSN Design Factors Scalability
  • Size Number of node (100 1000)
  • Density µ(R)(N?R2)/A
  • Protocol should
  • be able to scale to such high degree
  • take advantage of the high density of such
    networks

1
16
WSN Design Factors Production Costs
  • The cost of a single node must be low given the
    amount of functionalities
  • Much less than 1

1
17
WSN Design Factors Hardware Constraints
  • All these units combined together must
  • Extremely low power
  • Extremely small volume

1
18
WSN Design Factors Topology
  • Must be maintained specially in very high
    densities
  • Pre-deployment and deployment phase
  • Post-deployment phase
  • Re-deployment of additional nodes phase

1
19
WSN Design Factors Environment
  • May be inaccessible
  • either because of hostile environment
  • or because they are embedded in a structure
  • Impact of environment condition
  • Temperature
  • Humidity
  • Movement
  • Underwater
  • Underground

1
20
WSN Design Factors Environment
  • Busy intersections
  • Interior of a large machinery
  • Bottom of an ocean
  • Surface of an ocean during a tornado
  • Biologically or chemically contaminated field
  • Battlefield beyond the enemy lines
  • Home or a large building
  • Large warehouse
  • Animals
  • Fast moving vehicles
  • Drain or river moving with current

1
21
WSN Design Factors Transmission Media
  • RF
  • Infrared
  • Optical
  • Acoustic 3

1
22
WSN Design Factors Power Consumption
  • Power conservation
  • Sensing
  • Communication
  • Data processing

1
23
Some Research Projects
1
24
wireless sensor and actornetworks (WSANs)
  • WSAN Capabilities
  • Observing the physical world
  • Processing the data
  • Making decisions
  • Performing appropriate actions
  • WSAN applications
  • battlefield surveillance
  • microclimate control in buildings
  • nuclear, biological and chemical attack detection
  • Home automation
  • environmental monitoring

2
25
WSANs unique characteristics
  • Real-time requirement
  • Coordination
  • Sensor-Actor Coordination
  • Actor-Actor Coordination

2
26
WSN structure
  • A WSN typically has little or no infrastructure
  • There are two types of WSNs
  • Structured model
  • Unstructured model

3
27
Unstructured model
  • Densely deployed (many node)
  • Randomly Deployed
  • Can have uncovered regions
  • Left unattended to perform the task
  • Maintenance is difficult
  • managing connectivity
  • detecting failures

3
28
Structured model
  • Deployed in a pre-planned manner
  • Fewer nodes
  • Lower network maintenance
  • Lower cost
  • No uncovered regions

3
29
WSN constraints
  • Resource constraints
  • limited energy
  • short communication range
  • low bandwidth
  • limited processing
  • limited storage
  • Design constraints
  • application dependent
  • environment dependent
  • size of the network / number of node
  • deployment scheme
  • network topology (obstacle)

3
30
Available sensors in the market
  • Generic nodes (take measurements)
  • Light, Temperature, Humidity, barometric
    pressure, velocity, Acceleration, Acoustics,
    magnetic field
  • Gateway (bridge) node
  • gather data from generic sensors and relay them
    to the base station
  • higher processing capability
  • higher battery power
  • higher transmission (radio) range

3
31
Types of sensor network
  • Depending on the environment
  • terrestrial WSN
  • Ad Hoc (unstructured)
  • Preplanned (structured)
  • underground WSN
  • Preplanned
  • more expensive equipment, deployment, maintenance
  • underwater WSN
  • fewer sensor nodes( sparse deployment)
  • more expensive than terrestrial
  • acoustic wave communication
  • Limited bandwidth
  • long propagation delay
  • signal fading

32
Types of sensor network (cont.)
  • Depending on the environment
  • multi-media WSN
  • sensor nodes equipped with cameras and
    microphones
  • pre-planned to guarantee coverage
  • High bandwidth/low energy, QoS, filtering, data
    processing and compressing techniques
  • mobile WSN
  • ability to reposition and organize itself in the
    network
  • Start with Initial deployment and spread out to
    gather information
  • deployment, localization, self-organization,
    navigation and control, coverage, energy,
    maintenance, data process

33
WSN applications
3
34
WSN applications (Open research issues)
  • application-specific characteristics and
    requirements of
  • environmental monitoring
  • health monitoring
  • industrial monitoring
  • Military tracking
  • Coupled with todays technology
  • Lead to different hardware platforms and software
    development
  • more experimental work is necessary to make these
    applications more reliable and robust in the real
    world
  • Applying sensor technology to industrial
    applications will improve business

35
Tasks Classification
  • Systems
  • Each sensor node is an individual system
  • Development of new platforms, operating systems,
    and storage schemes
  • Communication protocols
  • Between sensors
  • In different layer(app, trspt, net, DLink, phy)
  • services
  • which are developed
  • to enhance the application
  • to improve system performance
  • and network efficiency

3
36
Internal sensor system
  • sensor platform
  • radio components
  • processors
  • Storage
  • sensors (multiple)
  • OS
  • OS must support these sensor platforms
  • researches
  • Designing platforms that support
  • automatic management
  • optimizing network longevity,
  • distributed programming

3
37
Platform Sample 1(Bluetooth-based sensor
networks)
  • WSN typically uses single freq (Share channel)
  • BTnodes use spread-spectrum transmission
  • A special version of TinyOS is used
  • Two radio communication
  • Master (up to 7 connection)
  • Slave
  • Note
  • Bluetooth is connection oriented
  • New node enables its slave radio
  • Topology connected tree
  • high throughput, high energy consumption

3
38
Platform Sample 2VigilNet(Detection-and-classifi
cation system)
  • detection and classification
  • vehicles
  • persons
  • persons carrying ferrous objects
  • 200 sensor nodes with
  • Magnetometer
  • motion sensor,
  • and a microphone
  • deployed in a preplanned manner
  • four tiers hierarchical architecture
  • sensor-level,
  • node-level,
  • group-level,
  • and base-level

3
39
Internal sensor system Standards
  • IEEE 802.15.4
  • standard for low rate wireless personal area
    networks (LR-WPAN)
  • low cost deployment
  • low complexity
  • low power consumption
  • topology star and peer-to-peer
  • physical layer 868/915 MHz 2.4 GHz
  • MAC layer CSMA-CA mechanism

3
40
Internal sensor system Standards
  • ZigBee
  • higher layer communication protocols built on the
    IEEE 802.15.4 standards for LR-PANs.
  • simple, low cost, and low power
  • embedded applications
  • can form mesh networks connecting hundreds to
    thousands of devices together.
  • types of ZigBee devices
  • ZigBee coordinator stores information, bridge
  • ZigBee router link groups of devices
  • ZigBee end device sensors, actuators communicate
    only to routers

3
41
Internal sensor system Standards
  • IEEE 802.15.3
  • physical and MAC layer standard high data rate
    WPAN.
  • support real-time multi-media streaming
  • data rates (11 Mbps to 55 Mbps)
  • time division multiple access (TDMA) gtQoS
  • synchronous and asynchronous data transfer
  • wireless speakers, portable video, wireless
    connectivity for gaming, cordless phones,
    printers, and televisions

3
42
Internal sensor system Standards
  • WirelessHART (released in September 2007)
  • Process measurement and control applications
  • based on IEEE 802.15.4
  • supports channel hopping, and time-synchronized
    messaging
  • Security with encryption, verification,
    authentication and key management
  • support mesh, star, and combined network
    topologies
  • manages the routing and network traffic

3
43
Internal sensor system Standards
  • ISA100.11a
  • defines the specifications for the OSI layer,
    security, and system management
  • low energy consumption, scalability,
    infrastructure, robustness
  • interoperability with other wireless devices
  • use only 2.4 GHz radio and channel hopping to
    minimize interference
  • provides simple, flexible, and scaleable security
    functionality.

3
44
Internal sensor system Standards
  • 6LoWPAN
  • IPv6-based Low power Wireless Personal Area
    Networks
  • over an IEEE 802.15.4 based network.
  • Low power device can communicate directly with IP
    devices using IPbased protocols
  • Wibree
  • designed for low power consumption, short-range
    communication, and low cost devices
  • is designed to work with Bluetooth
  • operates on 2.4 GHz
  • data rate of 1 Mbps
  • linking distance is 510 m.
  • was released publicly in October 2006.

3
45
Internal sensor system Storage
  • problems
  • storage space is limited
  • Communication is expensive
  • Solutions
  • Aggregation and compression
  • query-and-collect (selective gathering)
  • a storage model to satisfy storage constraints
    and query requirements
  • GEM Graph Embedding
  • provides an infrastructure for routing and
    data-centric storage
  • choosing a labeled guest graph
  • embed the guest graph onto the actual sensor
    topology
  • Each node has a label encoded with its position
  • each data item has a name that can be mapped to a
    label
  • TSAR Two-tier sensor storage architecture
  • Multi-resolution storage provides storage and
    long-term querying of the data for data-intensive
    applications

3
46
Internal sensor system Testbeds
  • Provides researchers a way to test their
    protocols, algorithms, network issues and
    applications in real world setting
  • Controlled environment to deploy, configure, run,
    and monitoring of sensor remotely
  • Some testbeds
  • ORBIT Open access research testbed for next
    generation wireless networks
  • 64 nodes, 1 GHZ
  • MoteLab web-based WSN testbed
  • central server handles scheduling, reprogramming
    and data logging of the nodes
  • Emulab remotely accessible mobile and wireless
    sensor (such as a robot)

3
47
Internal sensor system Diagnostics and debugging
support
  • Measure and monitor the sensor node performance
    of the overall network
  • to guarantee the success of the sensor network in
    the real environment
  • Sympathy
  • is a diagnosis tool for detecting and debugging
    failures in sensor networks
  • designed for data-collection applications
  • detects failures in a system by selecting metrics
    such as
  • Connectivity
  • data flow
  • nodes neighbor
  • can identify three types of failures self, path
    and sink
  • Analysis of data packet delivery
  • packet delivery performance at the physical and
    MAC layers

3
48
Internal sensor system Open research issues
  • optimization of (HW, SW, HW/SW) to make a WSN
    efficient
  • more practical platform solution for problems in
    new applications
  • data structure
  • Performance
  • energy-efficient storage
  • Performance
  • communication throughput when network size
    increases
  • Scalability issues can degrade system performance
  • Optimizing protocols at different layers
  • services to handle node before and after failures

3
49
Network services
  • Localization
  • Synchronization
  • Coverage
  • Compression and aggregation
  • Security

3
50
Network services Localization
  • Problem
  • determining the nodes location (position)
  • Solutions
  • global positioning system (GPS)
  • Simple
  • Expensive
  • outdoor
  • beacon (or anchor) nodes
  • does not scale well in large networks
  • problems may arise due to environmental
    conditions
  • proximity-based
  • Make use of neighbor nodes to determine their
    position
  • then act as beacons for other nodes

3
51
Network services Localization
  • Other solutions
  • Moores algorithm
  • distributed algorithm for location estimation
    without the use of GPS or fixed beacon (anchor)
    nodes
  • algorithm has three phases
  • cluster localization phase
  • cluster optimization phase
  • cluster transformation phase

3
52
Network services Localization
  • Other solutions
  • RIPS Radio Interferometric Positioning System
  • Two radio transmitters create an interference
    signal at slightly different frequencies
  • At least two receivers are needed to measure
    relative phase of two signal
  • The relative phase offset is a function of the
    relative positions

3
53
Network services Localization
  • Other solutions
  • Secure localization
  • goal is to prevent malicious beacon nodes from
    providing false location to sensors
  • Sensors must only accept information from
    authenticated beacon nodes
  • Sensors should be able to request location
    information at anytime
  • Upon a location request, information exchange
    must take place immediately and not at a later
    time.
  • SeRloc, Beacon Suite, DRBTS, SPINE, ROPE

3
54
Network services Localization
  • Other solutions
  • MAL Mobile-assisted localization
  • Mobile node collects distance information between
    itself and static sensor nodes for node
    localization
  • given a graph with measured distance edges

3
55
Network services Synchronization
  • Time synchronization is important for
  • routing
  • power conservation
  • Lifetime
  • Cooperation
  • Scheduling

3
56
Network services Synchronization
  • Uncertainty-driven approach
  • Lucarellis algorithm
  • Reachback firefly algorithm (RFA)
  • Timing-sync protocol for sensor network (TPSN)
  • CSMNS
  • Time synchronization (TSync)
  • Global synchronization

3
57
Network services Synchronization
  • Synchronization protocol classification
  • application-dependent features approaches
  • single-hop vs. multi-hop networks
  • stationary vs. mobile networks
  • MAC layer-based vs. standard-based
  • synchronization issues
  • adjusting their local clocks to a common time
    scale
  • masterslave synchronization
  • peer-to-peer synchronization
  • clock correction
  • untethered clocks
  • internal synchronization,
  • external synchronization,
  • Probabilistic synchronization,
  • deterministic synchronization,
  • sender to receiver synchronization,
  • and receiver-to-receiver synchronization.

3
58
Network services Coverage
  • Is important in evaluating effectiveness
  • Degree of coverage is application dependent
  • Impacts on energy conservation
  • Techniques
  • selecting minimal set of active nodes to be awake
    to maintain coverage
  • sensor deployment strategies

3
59
Network services Compression and aggregation
  • Both of them
  • reduce communication cost
  • increase reliability of data transfer
  • Data-compression
  • compressing data before transmission to base
  • Decompression occurs at the base station
  • no information should be lost
  • data aggregation
  • data is collected from multiple sensors
  • combined together to transmit to base station
  • Is used in cluster base architectures

3
60
Network services Security
  • Constraints in incorporating security into a WSN
  • limitations in storage
  • limitations in communication
  • limitations in computation
  • limitations in processing capabilities

3
61
Network services Open research issues
  • localization
  • efficient algorithms
  • minimum energy
  • minimum cost
  • minimum localization errors
  • Coverage optimizing for better energy
    conservation
  • time synchronization minimizing uncertainty
    errors over long periods of time and dealing with
    precision
  • compression and aggregation Development of
    various scheme
  • event-based data collection
  • continuous data collection
  • Secure monitoring protocols have to monitor,
    detect, and respond to attacks
  • It has done for network and data-link layer (can
    be improved)
  • Should be done for different layers of the
    protocol stack
  • Cross-layer secure monitoring is another research
    area

3
62
Communication protocol
  • Transport layer
  • Network layer
  • Data-link layer
  • Physical layer

3
63
Communication protocol Transport layer
  • Packet loss
  • may be due to
  • bad radio communication,
  • congestion,
  • packet collision,
  • memory full,
  • node failures
  • Detection and recovering
  • Improve throughput
  • Energy expenditure

3
64
Communication protocol Transport layer
  • Congestion control/packet recovery
  • hop-by-hop
  • intermediate cache
  • more energy efficient (shorter retransmission)
  • higher reliability
  • end-to-end
  • source caches the packet
  • Variable reliability

3
65
Communication protocol Transport layer
  • Sensor transmission control protocol (STCP)
  • Price-oriented reliable transport protocol (PORT)
  • GARUDA
  • Delay sensitive transport (DST)
  • Pump slowly, fetch quickly (PSFQ)
  • Event-to-sink reliable transport (ESRT)
  • Congestion detection and avoidance (CODA)

3
66
Communication protocol Transport layer (Open
research issues)
  • cross-layer optimization
  • selecting better paths for retransmission
  • getting error reports from the link layer
  • Fairness
  • assign packets with priority
  • frequently-changing topology
  • Congestion control with active queue management

3
67
Communication protocol Transport layer
3
68
Communication protocol Network layer
  • Important
  • energy efficiency
  • traffic flows
  • Routing protocols
  • location-based considers node location to route
    data
  • cluster-based employs cluster heads to do data
    aggregation and relay to base station

3
69
Communication protocol Network layer (Open
research issues)
  • Future research issues should address
  • Security
  • Experimental studies regarding security applied
    to different routing protocols in WSNs should be
    examined
  • QoS
  • guarantees end-to-end delay and energy efficient
    routing
  • node mobility
  • handle frequent topology changes and reliable
    delivery

3
70
Communication protocol Network layer
3
71
Communication protocol Data-link layer (Open
research issues)
  • system performance optimization
  • Cross-layer optimization
  • Cross-layer interaction can
  • reduce packet overhead on each layer
  • reduce energy consumption
  • Interaction with the MAC layer provide
  • congestion control information
  • enhance route selection
  • Comparing performance of existing protocols of
    static network in a mobile network
  • improve communication reliability and energy
    efficiency

3
72
Communication protocol Data-link layer
3
73
Communication protocol Physical layer
  • Bandwidth choices
  • Radio architecture
  • Modulation schemes

3
74
Communication protocol Physical layer (Open
research issues)
  • Minimizing the energy consumption
  • Optimizing of circuitry energy
  • reduction of wakeup and startup times
  • Optimizing of transmission energy
  • Modulation schemes
  • Future work
  • new innovations in low power radio design with
    emerging technologies
  • exploring ultra-wideband techniques as an
    alternative for communication
  • creating simple modulation schemes to reduce
    synchronization and transmission power
  • building more energy-efficient protocols and
    algorithms

3
75
Communication protocol Physical layer
3
76
Communication protocol Cross-layer interactions
(Open research issues)
  • Collaboration between all the layers to achieve
    higher
  • energy saving
  • network performance
  • network lifetime

3
77
Communication protocol Cross-layer interactions
3
78
Conclusion
  • Large number of application is exist regarding to
    WSN
  • Large number of work has done on WSN
  • There are still many open issue research in WSN
  • Open research area
  • Application-specific characteristic
  • Power efficient algorithm
  • Cross-layer optimization
  • more experimental work to reach more reliability
  • Improvement of existing protocol
  • Security
  • Error reduction in localization

3
79
Main references
  • Ian F. Akyildiz, Weilian Su, Yogesh
    Sankarasubramaniam, and Erdal Cayirci, A Survey
    on Sensor Networks, IEEE Communications Magazine,
    August 2002
  • Ian F. Akyildiz, Ismail H. Kasimoglu, Wireless
    sensor and actor networks research challenges,
    Elsevier Ad Hoc Networks 2 (2004) 351367
  • Jennifer Yick, Biswanath Mukherjee, Dipak Ghosal,
    Wireless sensor network survey, Elsevier Computer
    Networks 52 (2008) 22922330
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