Verification and Power Analysis of TinyOS with Hybrid Automata

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Verification and Power Analysis of TinyOS with
Hybrid Automata

• Sinem Coleri Mustafa Ergen
• EECS EECS
• csinem_at_eecs.berkeley.edu ergen_at_eecs.berkeley.edu

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Outline

• Introduction
• TinyOS
• TinyOS characteristics
• Hytech
• Hytech Description
• Verification of TinyOS
• Power Analysis of a TinyOS sensor node
• SHIFT
• SHIFT description
• Power Analysis of a Sensor Network
• Conclusion

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Introduction

• Why need sensor networks?
• Monitoring environment
• What is the characteristic of sensor networks?
• Deploy once and leave without future maintenance
• Why need verification?
• Guaranteed correct operation in every
  circumstance.
• Why need power analysis?
• Predict the lifetime.
• What type of modelling?
• Discrete events and continuous activities Hybrid
  Automata
• What are the tools?
• HyTech for verification, SHIFT for simulation
• What are the metrics?
• Power consumption of a single node
• Lifetime of the network

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TinyOS

• Component-based
• Modularity by assembling just the software
  components to synthesize app. from hardware
  components
• Components as reentrant cooperating state
  machines
• Event-based
• Components communicating through events and
  commands
• Power efficient
• Spending unused CPU cycles in sleep
• Turning radio off when not is use

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Complete TinyOS application

• Scheduler
• Graph of components
• Each component has
• Interface(.comp)
• Internal Implementation(.c)

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Complete TinyOS application Component

• Interface comprises of synchronous commands and
  asynchronous events
• Upper Interface
• Commands it implements
• Events it signals
• Lower Interface
• Commands it uses
• Events it handles
• Internal Storage
• Fixed-size frame containing the state of
  component
• Internal Implementation
• Light-weight threads tasks
• Command and event handlers

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Description of Application

• Describes the wiring of the interfaces
• Efficient modularity
• Optimization by static info

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Application Graph of Components
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Scheduling

• Events have higher priority
• Events preempt tasks
• Almost instantaneous event execution
• Not wait for long latency actions
• Small amount of work related to component state

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Scheduling

• Tasks have lower priority
• Tasks do not preempt events or other tasks
• Scheduled by FIFO scheduler
• Handled rapidly without blocking or polling
• Unused CPU cycles in sleep state

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Ex. Communication

post a task
Event handling
Put processor sleep
Task handling
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Hytech

• Hytech inputs
• System description
• Composition of linear hybrid automata
• Temporal Logic Requirement
• Hytech outputs
• Safety check
• Debugging traces

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From TinyOS to Hytech

• TinyOS component
• -gt Hytech automaton
• TinyOS event, commands
• -gt Hytech discrete events
• TinyOS clock cycle
• -gt Hytech discrete time step
• TinyOS energy
• -gt Hytech variable

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Overall View of TinyOS Automata
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Packet Generation and Application Automata
Application
Packet_generation
idle
rtgtcbit_time/ rt0, ptpt1, sync rfm_clock
rt0,pt0
at0
atgtcbetween/ at0, sync transmit_pack
rtltcbit_time ptltcidle drt1
ptgtcgeneration/ rt0, bit0, pt0, sync
rfm_clock
atltcbetween dat1
ptgtcidle/ rt0, bit1, pt0, sync rfm_clock
rtltcbit_time ptltcgeneration drt1
sync receive_pack/ sync trans_packet
rtgtcbit_time/ rt0, ptpt1, sync rfm_clock
generate
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RFM Automata
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Task Handler Automata
Task Handler
exec
dht0 dct0 denergycactive
sync rfm_rx_comp sync rfm_tx_comp /
htlt0/
idle
op
dht0 dct0 denergycinactive
htgt0 dht-1 dct0 denergycactive
sync rfm_clock/
sync rfm_clock/
sync decode/ htcdecode, ct0
sync encode/ htcencode, ct0
sync rfm_rx_comp sync rfm_tx_comp /
sync decode/ hthtcdecode, ct0
ctltctask_post dht0 dct1
denergycactive
dht0 dct0 denergycactive
sync encode/ hthtcencode, ct0
op_wait
ctgtctask_post/ sync post_task_done
op_exec
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Verification of TinyOS with Hytech Motivation
Application

Application assumes that packet is sent
successfully
transmitting
packet level
idle
idle
receiving
byte level
receiving
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Verification of TinyOS with Hytech

• Analysis commands for verification
• init_reg ..
• final_reg locrpackettransmit
  locrbytereceive
• reached reach forward from init_reg endreach
• if empty(reached final_reg)
• then prints working fine
• else print trace to final_reg using reached
• endif

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Power Analysis of TinyOS with Hytech

• Power analysis through variable energy by using
  trace generation feature of Hytech
• by setting
• final_reg tgt300000
• by checking variable energy at the end

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Power Analysis of TinyOS with Hytech

• As the number of children increases,
• time to wait before transmitting increases due to
  backoff
• number of packets to be forwarded increases

BS
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Power Consumption vs. of Children
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SHIFT

• Describes dynamic networks of hybrid automata
• Components created, interconnected, destroyed as
  the system evolves
• Components interact through their inputs, outputs
  and exported events

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Clustering of the Network

• Uniform Distribution
• 100 node
• 100m x 100m
• 4 Macro Clusters
• Children determined according to position
  distribution

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Modeling of a sensor network

• 4 Types of Node Automata.
• Create an instance for each node.
• Destroy the instance when the node dies.
• Distribute the load to its group.
• Notify upper group when there is a death.

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Model of a node
X Energy F from the HyTech result.
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Result

• Need powerful nodes in group 1.
• Group 1 suffers from high load and backoff time.
• Group 4 dies at the same time.

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Conclusion

• Sensor nodes are aimed to be left without
  maintenance.
• Power is a detrimental concern in sensor world.
• Verification is needed for reliability.
• Power analysis is needed for the lifetime of the
  node.
• Network power analysis is needed for the lifetime
  of the network.
• Verification and Power analysis with HyTech .
• Network power analysis with SHIFT.