Transcript Energy Efficient Communication in Wireless Sensor Networks

Energy Efficient Communication
in Wireless Sensor Networks
Yingyue Xu
7/18/2015
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Characteristics of Sensor Devices
• Ability to monitor a wide variety of
ambient conditions:
– temperature,
– pressure,
– mechanical stress level on attached
objects…
• Will be equipped with significant
processing, memory, and wireless
communication capabilities.
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Sensor Node Architecture
Location Finding
System
Sensor
ADC
Mobilizer
Processor
Transceiver
Storage
PowerUnit
Power
Generator
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Sensor Networks
• Large number of heterogeneous sensor
devices
– Scalable
• Energy constrained
• Dynamic, adaptive to changeing
• Data centric: data is requested based on
certain attributes, SPIN and Direct
diffusion
• Application specific
• Unattended operation, configuration done
automatically and repeatedly
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Sensor Networks Architecture
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Design Factors(Akyildiz et al, IEEE
Comm. Mag. Aug. 2002)
–
–
–
–
Fault Tolerance (sustain functionalities)
Scalability (hundreds or thousands)
Production Cost (now $10, near future $1)
Hardware Constraints(small, environment,
unattended)
– Network Topology (pre-, post-, and redeployment)
– Transmission Media (RF (WINS), Infrared
(Bluetooth), and Optical (Smart Dust))
– Power Consumption (with < 0.5 Ah, 1.2 V)
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Energy Save Ideas
Task Level
Acceptable Functionality
with Reduced Computations
Algorithm Level
Collaborative Signal Processing
and
Coordinated Communications
Protocols Level
Power Aware Routing
and
Selective Multicasting
Physical Level
Radio Power Control
and
Dynamic Bandwidth Management
Application
and
QoS Driven
Energy,
Delay, and
Bandwidth
Management
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Energy Save Methods
Shutdown
Put a node into sleep state
MAC layer
Power Save Protocols
Network layer
[Srinivasan01]
Scaling
Synchronous
IEEE 802.11
Topology
based
Span,
LEACH
Asynchronous
Application
layer
Power Control
Techniques
BECA/AFECA
Mobile-agent-based
Energy aware application, localization, tracking
Topology control [Tang01]
Assign per-node transmit
powers
Maximum PA route
Maximum lifetime
routing
Minimum energy route
Minimum hop route
Maximum minimum PA node route
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Sensor node energy model
Micro Sensor Node
Power Model
(Energy Consumers and Providers)
Radio Model
CPU Model
Battery
Model
Sensor #1 Model
Sensor #2 Model
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Battery model
1. linear model
2. discharge rate dependent model
3. relaxation model
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Radio model
Etx  (11   2 d ) * r
n
Erx  12 * r
W E
Tx
elec
 ERF  E
Rx
elec
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Computation model
Etot  C V  Vdd Ileak t
2
tot dd
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Sensing model
Esen sin g   3 * r
 3  12
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Power saving mode
• Turning the transceiver off may not
always be efficient. Operation in a
power-saving mode is energyefficient only if the time spent in that
mode is greater than a certain
threshold
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Multiple hops
• Using several short hops may be
more energy efficient than using one
large hop.
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Some notes
• Sending>Receiving>Idle>Sleep
• Small packets (such as “hello”
message) are a relatively expensive
mechanism
• Broadcast is expensive in a dense
network
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Mobile agent paradigm
• Good for distributed environment, such as
sensor networks
• Low delay
• Energy efficient
– Migrate the nodes near the phenomenon, other nodes can
keep in sleep state
– Reduce network traffic
– Itinerary design can further improve the lifetime of
sensor network
• Fault tolerant
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