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XYZ: A Motion-Enabled, Power XYZ: A Motion-Enabled, Power Aware Sensor Node Platform for Aware Sensor Node Platform for

Distributed Sensor Network Distributed Sensor Network ApplicationsApplications

Presenter: JamesPresenter: James

D. Lymberopoulos, A. Savvides

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Why this paper?Why this paper?• Similarity to underwater sensor network:

– 3 Dimensional – Motion enabled

• Smart dust or Stupid dust?

• Detailed power consumption analysis

• Some interesting observations

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ENALAB 3-D testbedENALAB 3-D testbed

• XYZ sensor nodes: – The fundamental building block of sensor infrastructure and testbed

for various applications at ENALAB, Yale University • Applications:

– Surveillance, Child motion monitoring, Traffic management, etc.

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XYZ HardwaresXYZ Hardwares

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XYZ ArchitectureXYZ Architecture• Main Processing Unit:

– OKI ML67Q5002 (ARM7 core)– 57.6MHz– 7 hardware timers– 256KB Flash, 32KB RAM and 4KB boot ROM

• Radio Unit: – CC2420– IEEE 802.15.4

• 2Mbits(256kbit x 16) external RAM• Temperature Sensor & Light Sensor• Mobility Support Mechanism• Three Rechargeable Batteries:

– 3 x 1200~2000mAH

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Long Term Deep Sleep Long Term Deep Sleep ModeMode

• Power Consumption: 30uA• Sleep Interval: 1 minute ~ 200 years

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Software InfrastructureSoftware Infrastructure

• An OS designed for mote-class wireless sensor network from UCLA

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Overview of SOSOverview of SOS

• Reconfigurable– Loadable Modules

• Microkernel

• Event Driven

• Non-preemptive– For non-concurrency-intensive applications

• Size: – Tens of KBytes

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SOS and TinyOSSOS and TinyOSSOS TinyOS

Microkernel Monolith

Dynamic Memory Allocation

Fixed Frame

Dynamic Loadable Modules

Fixed modules when deployed

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XYZ support API in SOSXYZ support API in SOS• Device Drivers Module

– Radio, Real Time Clock, ADC, UART, timers and DMA controllers.

• Sleep Mode Driver Module– STANDBY, HALT, Deep Sleep

• Radio Manager Module– For configure the communication

subsystem.• Frequency Manager Module

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Power CharacterizationPower Characterization• Measurement

Setup

– PCI-DAS6036:• For CPU, I/O and Radio

– TDS2012: • For mode transition

energy overheads

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CPU Frequency ScalingCPU Frequency Scaling

57.6( ,15.18 )32

MHz mA

(57.6 ,78.28 )MHz mA

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Transitioning Overheads:Transitioning Overheads:

• In HALT mode, the power consumption heavily depends on the previous state of the processor.

• It’s better first scale the frequency down before going to HALT mode.

From Active to STANDBY or HALTFrom Active to STANDBY or HALT

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Transitioning Overheads:Transitioning Overheads:

• Transition times and energy for the STANDBY mode are significantly higher.

• It’s better to first reduce the clock frequency before jump to sleep

From STANDBY or HALT to sleepFrom STANDBY or HALT to sleep

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Communication OverheadsCommunication Overheads

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Main ContributionsMain Contributions

• A long-term ultra low power sleep mode

• The ability to scale down or scale up its computation ability.

• Insightful power characterization.

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DiscussionsDiscussions• Using powerful processor may not necessarily

mean a waste of energy and money.• Micaz and XYZ

XYZ Micaz

MCU ARM7 ATmega103L

Frequency 57.6MHz 4MHz

Memory 256KB ROM/32KB RAM

128KB ROM/ 4KB RAM

Energy for Active Mode (When Radio is listening)

35.8~90mA >28mA

Costs $150 $125

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ThanksThanks

• Questions and Comments?