View
222
Download
4
Category
Tags:
Preview:
Citation preview
Lan F.Akyildiz,Weilian Su, Erdal Cayirci ,and Yogesh
sankarasubramaniamIEEE Communications Magazine 2002
Speaker:earl
A Survey on Sensor Networks
Outline
IntroductionCommunication architectureProtocol stackConclusion
Sensor Networks…low-cost, rapid deployment, self-organizing, and fault toleranceApplication areas: heath, military, and homeLarge number of sensor nodes that are densely deployedNodes use their processing abilities to locally carry out simple computations and transmit the required and partially processed data
Introduction
Application areas - heath
Compress data to reduce storage and communication bandwidth!
Application areas - military
Inactive Sensor
Application areas
Application areas
Active Sensor
Application areas
Ad hoc networks are not suitable for the sensor networks because of their unique features and application requirement The sensor network may have a much
larger number of nodes Transmission power and radio range Topology changes Mobility rate Power conservation
Introduction
Internet and Satellite
Sink
Task managernode
User
Sensor nodesSensor field
A
B
CDE
Communication Architecture
Fault Tolerance the ability to sustain sensor network functionalities
without any interruption due to sensor node failures
Scalability the density of sensor nodes can range from few
sensor nodes to few hundred sensor nodes in a region
Production Costs the cost of sensor node should be much less than
US$1 in order for the sensor network to be feasible
Environment can work in different environments
Design Factors
Power Unit Power
generator
Location finding system Mobilizer
TransceiverSensor ADC
SensingUnit
ProcessingUnit
Processor
Storage
Design FactorsHardware Constraints
Sensor Network Topology Predeployment and deployment phase Post-deployment phase Redeployment of additional nodes phase
Transmission Media links between nodes can be formed by
radio, infrared, or optical media
Power Consumption battery lifetime design of power-aware protocols and
algorithms
Design Factors
Protocol Stack
Application layer
Transport layer
Network layer
Data link layer
Physical layer
Pow
er m
an
ag
em
en
t pla
ne
Mob
ility m
an
ag
em
en
t pla
ne
Task m
an
ag
em
en
t pla
ne
Multiplexing of data streamsData frame detectionMedium access and error controlEnsures reliable point-to-point and point-to-multipoint connections in a communication network
The Data Link Layer
Goals share communication resources
between sensor nodes fairly and efficiently
The Data Link Layer - Medium Access Control
MAC protocol Power conservation
SMACS and EAR[13] Random wakeup during setup and turning off while idle
Hybrid TDMA/FDMA[8] Hardware-based approach for system energy minimization
CSMA-based[9] Constant listening time for energy efficiency
The Data Link Layer -Some of the proposed MAC protocols
Power saving modes of operation Turning the transceiver off during idling
may not always be efficient due to energy spent in turning it back on each time
Error control Two modes of error control:
Forward Error Correction(FEC) decoding complexities
Automatic Repeat Request (ARQ) additional retransmission energy cost and
overhead
The Data Link Layer
The Data Link Layer-Research issues
MAC for mobile sensor networksDetermination of lower bounds on the energy required for sensor network self-organizationError control coding schemesPower-saving modes of operation
Task: energy efficient routes
Sink
A (PA=2)
B (PA=2)
C (PA=2) T
D (PA=3)
E (PA=1)
F (PA=4)
α
1=1
α
α10=2
α
αα
α
α
α
α 5=2
3=2
4=2
2=1 6=2
7=1
8=2
9=2
Route 1: Sink-A-B-T, total PA=4, total α = 3 Route 2: Sink-A-B-C-T, total PA=6, total α = 6Route 3: Sink-D-T, total PA=3, total α = 4Route 4: Sink-E-F-T, total PA=5, total α = 6
Approaches:• Minimum PA route: route 4• Minimum Energy (ME) route: route 1• Minimum hop (MH) route: route 3• Maximum minimum PA node route: route 3
PA: available powerα:: energy required
Network Layer
Data Aggregation, data fusion
AB C
DE
FG
Sink
Network Layer
Floodingeach node receiving a data or management packet repeats it by broadcasting Deficiencies
Implosion Overlap
Gossipingsend the incoming packets to a randomly selected neighbor Deficiency: takes a long time to propagate
the message to all sensor nodes
Network Layer -Routing techniques
Sensor Protocols for Information via Negotiation (SPIN)
Step 1
ADV
Step 2
REQ
Step 3
DATA
Step 4
ADV REQ
Step 5 Step 6
DATA
Network Layer
Sequential Assignment Routing (SAR) Creates multiple trees where the root of
each tree is a one-hop neighbor from the sink
Low-Energy Adaptive Clustering Hierarchy (LEACH) Forms clusters to minimize energy
dissipation
Directed diffusion Sets up gradients for data to flow from
source to sink during interest dissemination
Network Layer
Network Layer
LEACH and Directed diffusionBS
Sensor node
Cluster head
Cluster
Base station
LEACHDirected diffusion
Conclusion
Sensor network is a new Research issue
Recommended