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Energy Efficient Communication in Wireless Sensor Networks

Yingyue Xu

04/19/23

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Characteristics of Sensor DevicesCharacteristics 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

Power Unit Power Generator

Location Finding System

Mobilizer

Sensor ADC Processor

Storage

Transceiver

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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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– 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 re-

deployment)– Transmission Media (RF (WINS), Infrared

(Bluetooth), and Optical (Smart Dust))– Power Consumption (with < 0.5 Ah, 1.2 V)

Design Factors(Akyildiz et al, IEEE Comm. Mag. Aug. 2002)

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Energy Save Ideas

Task LevelTask Level

Algorithm LevelAlgorithm Level

Protocols LevelProtocols Level

Physical LevelPhysical Level

Acceptable Functionality with Reduced Computations

Acceptable Functionality with Reduced Computations

Collaborative Signal Processing and

Coordinated Communications

Collaborative Signal Processing and

Coordinated Communications

Power Aware Routing and

Selective Multicasting

Power Aware Routing and

Selective Multicasting

Radio Power Control and

Dynamic Bandwidth Management

Radio Power Control and

Dynamic Bandwidth Management

Application and

QoS Driven Energy,

Delay, and Bandwidth

Management

Application and

QoS Driven Energy,

Delay, and Bandwidth

Management

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Energy Save Methods

Power Save Protocols

Network layer

MAC layer

Topology based

Synchronous

Asynchronous

Application layer

Power Control Techniques

Topology control [Tang01]

Maximum lifetime routing

Shutdown

Scaling

Mobile-agent-based

Put a node into sleep state

Span, LEACH

IEEE 802.11

BECA/AFECA

[Srinivasan01]

Energy aware application, localization, tracking

Assign per-node transmit powers

Maximum PA route

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)

Battery Model

Radio Model

CPU Model

Sensor #1 Model

Sensor #2 Model

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1. linear model

2. discharge rate dependent model

3. relaxation model

Battery model

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Radio model

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Computation model

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Sensing model

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• Turning the transceiver off may not always be efficient. Operation in a power-saving mode is energy-efficient only if the time spent in that mode is greater than a certain threshold

Power saving mode

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• Using several short hops may be more energy efficient than using one large hop.

Multiple hops

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• Sending>Receiving>Idle>Sleep

• Small packets (such as “hello” message) are a relatively expensive mechanism

• Broadcast is expensive in a dense network

Some notes

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• 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

Mobile agent paradigm