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Verification and Power Analysis of TinyOS with Hybrid Automata
Sinem Coleri Mustafa Ergen
EECS EECS
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 2
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
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 3
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
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 4
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
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 5
Complete TinyOS application
Scheduler Graph of components
Each component has Interface(.comp) Internal Implementation(.c)
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 6
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
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 7
Description of Application
Describes the wiring of the interfaces Efficient modularity
Optimization by static info
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 8
Application Graph of Components
RFM
Radio byte
Radio Packet
photo
clocksbit
byte
packet
sensing applicationapplication
HW
SW
ADC
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 9
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
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 10
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
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 11
Ex. Communication
RFM Bit Level
Byte Level
Packet Level
Event handling
Task handling
Put processor sleep
…
post a task
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 12
Hytech
Hytech inputs System description
Composition of linear hybrid automata Temporal Logic Requirement
Hytech outputs Safety check Debugging traces
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 13
From TinyOS to Hytech
TinyOS component-> Hytech automaton
TinyOS event, commands-> Hytech discrete events
TinyOS clock cycle-> Hytech discrete time step
TinyOS energy -> Hytech variable
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 14
Overall View of TinyOS Automata
RFM
Radio byte
Radio Packet
bit
byte
packet
sensing applicationapplication
Task handler
Packet generation
rfm_clock
transmit_pack
rfm_rx_ev
rfm_tx_ev
rfm_rx_comp
rfm_tx_comp
rx_byte_ready
tx_byte_ready
tx_byte
packet_done_neg
packet_done_pos post_encode
post_decode
receive_pack
rfm_clock
rfm_rx_comp
rfm_tx_comp
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 15
Packet Generation and Application Automata
rt<=cbit_timept<=cidle drt=1
rt<=cbit_timept<=cgeneration drt=1
rt>=cbit_time/rt’=0, pt’=pt+1,sync rfm_clock
rt>=cbit_time/rt’=0, pt’=pt+1,sync rfm_clock
pt>=cidle/rt’=0, bit’=1,pt’=0,sync rfm_clock
pt>=cgeneration/rt’=0, bit’=0,pt’=0,sync rfm_clock
Packet_generation Application
rt=0,pt=0at=0
idle
generate
at<=cbetween dat=1
at>=cbetween/at’=0, sync transmit_pack
sync receive_pack/sync trans_packet
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 16
RFM AutomataRFM
drfmt=0
sync rfm_clock/rfmt’=0,energy’=energy+crec
rfmt<=crec_handler drfmt=1
rfmt>=crec_handler/sync rfm_rx_ev
drfmt=0
sync rfm_rx_comp/
drfmt=0
sync rfm_clock/rfmt’=0,energy’=energy+ctrans
rfmt<=ctrans_handler drfmt=1
rfmt>=crec_handler/sync rfm_tx_ev
drfmt=0
syncrfm_tx_comp/
sync rfm_tx_comp/
sync rfm_rx_comp/
receive
rec_energy rec_wait
transmit
trans_waittrans_energy
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 17
Task Handler AutomataTask Handler
dht=0dct=0denergy=cinactive
sync encode/ht’=cencode,ct’=0
sync decode/ht’=cdecode,ct’=0
ct<=ctask_post dht=0 dct=1 denergy=cactive
ct>=ctask_post/sync post_task_done
dht=0 dct=0denergy=cactive
sync rfm_rx_comp |sync rfm_tx_comp /
ht>=0dht=-1dct=0denergy=cactive
ht<=0/
sync rfm_clock/
sync rfm_clock/
sync rfm_rx_comp |sync rfm_tx_comp /
dht=0dct=0denergy=cactive
sync encode/ht’=ht+cencode,ct’=0
sync decode/ht’=ht+cdecode,ct’=0
idleop
op_waitop_exec
exec
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 18
Verification of TinyOS with Hytech: Motivation
RFM Bit Level
Byte Level
Packet Level
idle packet level
byte levelreceiving
idle
…
Application
transmitting
Application assumes that packet is sent successfully
receiving
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 19
Verification of TinyOS with Hytech
Analysis commands for verification:init_reg := …..;
final_reg := loc[rpacket]=transmit & loc[rbyte]=receive;
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;
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 20
Power Analysis of TinyOS with Hytech
Power analysis through variable energy by using trace generation feature of Hytech by setting
final_reg = t>300000; by checking variable energy at the end
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 21
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
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 22
Power Consumption vs. # of Children
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 23
SHIFT
Describes dynamic networks of hybrid automata Components created, interconnected, destroyed as the system
evolves Components interact through their inputs, outputs and exported
events
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 24
Clustering of the Network
Uniform Distribution
100 node 100m x 100m 4 Macro Clusters Children
determined according to position distribution
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 25
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.
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 26
Model of a node
X – EnergyF – from the HyTech result.
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 27
Result
Need powerful nodes in group 1.
Group 1 suffers from high load and backoff time.
Group 4 dies at the same time.
EE291E Hybrid Systems – T. John Koo and Shankar Sastry 28
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.
