wireless ad hoc network (fall 2008) wsn survey and research challenges wireless sensor networks...

Wireless Ad hoc Network (Fall 2008) WSN survey and research challenges

Wireless Sensor networksWireless Sensor networkssurvey and research challengessurvey and research challenges

Presented byPresented by

Hosein Sabaghian-BidgoliHosein [email protected]@gmail.com

January 11, 2009

University of TehranUniversity of Tehran

Dept. Electrical and Computer EngineeringDept. Electrical and Computer Engineering

Wireless Ad hoc Network (Fall 2008) WSN survey and research challenges2

OutlinesOutlines Main references Introduction

Definition Communication Architecture Protocol stack WSN Characteristics WSN Design factors

WSANs WSN Structures WSN Constraints WSN Applications WSN types .


Outlines (cont.)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


Main referencesMain references

1. Ian F. Akyildiz, Weilian Su, Yogesh Sankarasubramaniam, and Erdal Cayirci, A Survey on Sensor Networks, IEEE Communications Magazine, August 2002

2. Ian F. Akyildiz, Ismail H. Kasimoglu, Wireless sensor and actor networks research challenges, Elsevier Ad Hoc Networks 2 (2004) 351–367

3. Jennifer Yick, Biswanath Mukherjee, Dipak Ghosal, Wireless sensor network survey, Elsevier Computer Networks 52 (2008) 2292–2330


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IntroductionIntroductionWSN WSN DefinitionDefinition

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

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IntroductionIntroductionWSN communication ArchitectureWSN communication Architecture

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IntroductionIntroductionComponents of Sensor NodeComponents of Sensor Node

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IntroductionIntroductionProtocol StackProtocol Stack

Protocols should be Power aware Location aware Application aware

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IntroductionIntroductionWSN Characteristics WSN 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

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IntroductionIntroductionWSN Design FactorsWSN Design Factors

Fault Tolerance Scalability Production Costs Hardware Constraints Sensor Network Topology Environment Transmission Media Power Consumption [1]


WSN Design Factors WSN Design Factors Fault ToleranceFault 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.

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WSN Design Factors WSN Design Factors ScalabilityScalability

Size: Number of node (100 ~1000) Density : μ(R)=(NR2)/A Protocol should

be able to scale to such high degree take advantage of the high density of such

networks

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WSN Design Factors WSN Design Factors Production CostsProduction Costs

The cost of a single node must be low given the amount of functionalities

Much less than $1

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WSN Design Factors WSN Design Factors Hardware ConstraintsHardware Constraints

All these units combined together must Extremely low power Extremely small volume

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WSN Design Factors WSN Design Factors TopologyTopology

Must be maintained specially in very high densities Pre-deployment and deployment phase

Post-deployment phase

Re-deployment of additional nodes phase

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WSN Design Factors WSN Design Factors EnvironmentEnvironment

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

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WSN Design Factors WSN Design Factors Transmission MediaTransmission Media

RF Infrared Optical Acoustic [3]

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WSN Design Factors WSN Design Factors Power ConsumptionPower Consumption

Power conservation Sensing Communication Data processing

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wireless sensor and actorwireless sensor and actornetworks (WSANs)networks (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

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WSANs unique characteristicsWSANs unique characteristics

Real-time requirement Coordination:

Sensor-Actor Coordination Actor-Actor Coordination

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WSN structureWSN structure

A WSN typically has little or no infrastructure

There are two types of WSNs Structured model Unstructured model

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Unstructured modelUnstructured model

Densely deployed (many node) Randomly Deployed Can have uncovered regions Left unattended to perform the task Maintenance is difficult

managing connectivity detecting failures

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Structured modelStructured model

Deployed in a pre-planned manner Fewer nodes Lower network maintenance Lower cost No uncovered regions

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WSN constraintsWSN 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)

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Available sensors in the marketAvailable 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

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Types of sensor networkTypes of sensor network

Depending on the environment1. terrestrial WSN

– Ad Hoc (unstructured)– Preplanned (structured)

2. underground WSN– Preplanned– more expensive equipment, deployment, maintenance

3. underwater WSN – fewer sensor nodes( sparse deployment)– more expensive than terrestrial– acoustic wave communication

Limited bandwidth long propagation delay signal fading


Types of sensor network (cont.)Types of sensor network (cont.)

Depending on the environment4. 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

5. 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


WSN applicationsWSN applications

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WSN applications (WSN applications (Open research issues)Open research issues)

application-specific characteristics and requirements of environmental monitoring health monitoring industrial monitoring Military tracking

Coupled with today’s 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


Tasks ClassificationTasks 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

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Internal sensor systemInternal 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

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Platform Sample 1Platform Sample 1(Bluetooth-based sensor networks)(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

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Platform Sample 2:VigilNetPlatform Sample 2:VigilNet((Detection-and-classification systemDetection-and-classification 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

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Internal sensor system Internal sensor system StandardsStandards

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

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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

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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) =>QoS synchronous and asynchronous data transfer wireless speakers, portable video, wireless

connectivity for gaming, cordless phones, printers, and televisions

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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

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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.

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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 5–10 m. was released publicly in October 2006.

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Internal sensor system Internal sensor system StorageStorage

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

1. choosing a labeled guest graph2. 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

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Internal sensor system Internal sensor system TestbedsTestbeds

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]


Internal sensor system Internal sensor system Diagnostics and debugging supportDiagnostics 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 – node’s 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

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Internal sensor system Internal sensor system Open research issuesOpen 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

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Network servicesNetwork services

Localization Synchronization Coverage Compression and aggregation Security

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Network services Network services LocalizationLocalization

Problem: determining the node’s 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

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Other solutions: Moore’s 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

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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

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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

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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

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Network services Network services SynchronizationSynchronization

Time synchronization is important for routing power conservation Lifetime Cooperation Scheduling

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Uncertainty-driven approach Lucarelli’s algorithm Reachback firefly algorithm (RFA) Timing-sync protocol for sensor network

(TPSN) CSMNS Time synchronization (TSync) Global synchronization

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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– master–slave 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.

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Network services Network services CoverageCoverage

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

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Network services Network services Compression and aggregationCompression 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

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Network services Network services SecuritySecurity

Constraints in incorporating security into a WSN limitations in storage limitations in communication limitations in computation limitations in processing capabilities

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Network services Network services Open research issuesOpen 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

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Communication protocolCommunication protocol

Transport layer Network layer Data-link layer Physical layer

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Communication protocol Communication protocol Transport layerTransport layer

Packet loss may be due to

– bad radio communication, – congestion, – packet collision, – memory full, – node failures

Detection and recovering– Improve throughput – Energy expenditure

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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

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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):

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Communication protocol Communication protocol Transport layerTransport layer (Open research issues) (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

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Communication protocol Communication protocol Network layerNetwork 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]


Communication protocol Communication protocol Network layer Network layer (Open research issues)(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

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Communication protocol Communication protocol Data-link layerData-link layer (Open research issues)(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

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Communication protocol Communication protocol Physical layerPhysical layer

Bandwidth choices Radio architecture Modulation schemes

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Communication protocol Communication protocol Physical layerPhysical layer (Open research issues)(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

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Communication protocol Communication protocol Cross-layer interactionsCross-layer interactions (Open research issues)(Open research issues)

Collaboration between all the layers to achieve higher energy saving network performance network lifetime

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ConclusionConclusion 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

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Main referencesMain references

1. Ian F. Akyildiz, Weilian Su, Yogesh Sankarasubramaniam, and Erdal Cayirci, A Survey on Sensor Networks, IEEE Communications Magazine, August 2002

2. Ian F. Akyildiz, Ismail H. Kasimoglu, Wireless sensor and actor networks research challenges, Elsevier Ad Hoc Networks 2 (2004) 351–367

3. Jennifer Yick, Biswanath Mukherjee, Dipak Ghosal, Wireless sensor network survey, Elsevier Computer Networks 52 (2008) 2292–2330

wireless ad hoc network (fall 2008) wsn survey and research challenges wireless sensor networks...

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