Formal Verification of Real-Time
Wireless Sensor Networks Protocols
with Realistic Radio Links
Alexandre Mouradian
Isabelle Augé-Blum
RTNS 2013 ---- 18/10/2013
Alexandre Mouradian - RTNS 13 - 18/10/2013
1 / 12
Wireless Sensor Networks
Small battery-powered electronic devices
Adhoc multi-hops large scale networks
Unreliable links
Alexandre Mouradian - RTNS 13 - 18/10/2013
2 / 12
Anomaly detection
Critical applications:
Forest fire detection
Landslide detection
...
sink
Required:
Timeliness
"Does the alarm reach the sink before the deadline?"
There is a need for
Formal verification
Alexandre Mouradian - RTNS 13 - 18/10/2013
3 / 12
WSN verification in the
literature
Model Checking:
[1] Tschirner, S., Xuedong, L., and Yi, W. (2008). Model-based validation of qos properties
of biomedical sensor networks. ACM EMSOFT, pages 69–78, Atlanta, USA.
[2] Watteyne, T., Augé-Blum, I., and Ubéda, S. (2006). Dual-mode real-time mac protocol
for wireless sensor networks : a validation/simulation approach. InterSense, page 2, Nice, France.
[3] Fehnker, A., Van Hoesel, L., and Mader, A. (2007). Modelling and verification of the lmac
protocol for wireless sensor networks. IFM, pages 253–272, Oxford, UK.
.
Senor Network Calculus
[4] Schmitt, J. B., Zdarsky, F. a., and Thiele, L. (2007). A Comprehensive Worst-Case Calculus for
Wireless Sensor Networks with In-Network Processing. IEEE RTSS, Tucson, USA.
.
Probabilistic Model Checking:
[4] Fruth, M. (2011). Formal Methods for the Analysis of Wireless Network Protocols. PhD thesis, Oxford University.
Alexandre Mouradian - RTNS 13 - 18/10/2013
4 / 12
WSN verification in the
literature
Model Checking:
[1] Tschirner, S., Xuedong, L., and Yi, W. (2008). Model-based validation of qos properties
of biomedical sensor networks. ACM EMSOFT, pages 69–78, Atlanta, USA.
[2] Watteyne, T., Augé-Blum, I., and Ubéda, S. (2006). Dual-mode real-time mac protocol
for wireless sensor networks : a validation/simulation approach. InterSense, page 2, Nice, France.
[3] Fehnker, A., Van Hoesel, L., and Mader, A. (2007). Modelling and verification of the lmac
protocol for wireless sensor networks. IFM, pages 253–272, Oxford, UK.
.
Senor Network Calculus
[4] Schmitt, J. B., Zdarsky, F. a., and Thiele, L. (2007). A Comprehensive Worst-Case Calculus for
Wireless Sensor Networks with In-Network Processing. IEEE RTSS, Tucson, USA.
.
Probabilistic Model Checking:
[4] Fruth, M. (2011). Formal Methods for the Analysis of Wireless Network Protocols. PhD thesis, Oxford University.
Alexandre Mouradian - RTNS 13 - 18/10/2013
4 / 12
Analysis of the problem(1):
Radio link
E
R
Alexandre Mouradian - RTNS 13 - 18/10/2013
5 / 12
Analysis of the problem(1):
Radio link
E
R
Alexandre Mouradian - RTNS 13 - 18/10/2013
5 / 12
Analysis of the problem(1):
Radio link
E
R
Alexandre Mouradian - RTNS 13 - 18/10/2013
5 / 12
Analysis of the problem(1):
Radio link
E
R
Alexandre Mouradian - RTNS 13 - 18/10/2013
5 / 12
Analysis of the problem(1):
Radio link
E
R
Alexandre Mouradian - RTNS 13 - 18/10/2013
5 / 12
Analysis of the problem(1):
Radio link
E
R
Alexandre Mouradian - RTNS 13 - 18/10/2013
5 / 12
Analysis of the problem(1):
Radio link
E
R
Alexandre Mouradian - RTNS 13 - 18/10/2013
5 / 12
Analysis of the problem(1):
Radio link
E
R
Alexandre Mouradian - RTNS 13 - 18/10/2013
5 / 12
Analysis of the problem(1):
Radio link
E
R
Alexandre Mouradian - RTNS 13 - 18/10/2013
Modulation
5 / 12
Analysis of the problem(1):
Radio link
E
R
Alexandre Mouradian - RTNS 13 - 18/10/2013
Modulation
Signal
attenuation
5 / 12
Analysis of the problem(2):
Topology dynamics
sink
Alexandre Mouradian - RTNS 13 - 18/10/2013
6 / 12
Analysis of the problem(2):
Topology dynamics
sink
'
Alexandre Mouradian - RTNS 13 - 18/10/2013
6 / 12
Analysis of the problem(2):
Topology dynamics
sink
'
Alexandre Mouradian - RTNS 13 - 18/10/2013
6 / 12
Analysis of the problem(2):
Topology dynamics
sink
'
"With wich topologies the protocol can
provide real-time communications ? "
Reliability
Alexandre Mouradian - RTNS 13 - 18/10/2013
6 / 12
Verification algorithm
Output: probability that the real-time property holds
Generate logical topologies: T
Select topologies: T'
verify topology in T'
Does the
Property
hold ?
yes
PPv=PPv+Ptopo
no
yes
Not verified
topology in T' ?
no
Output: PPv
Alexandre Mouradian - RTNS 13 - 18/10/2013
7 / 12
Verification algorithm
Output: probability that the real-time property holds
Generate logical topologies: T
There are 2N topologies !!!
Select topologies: T'
verify topology in T'
Does the
Property
hold ?
yes
PPv=PPv+Ptopo
no
yes
Not verified
topology in T' ?
no
Output: PPv
Alexandre Mouradian - RTNS 13 - 18/10/2013
7 / 12
Verification algorithm
Output: probability that the real-time property holds
Generate logical topologies: T
There are 2N topologies !!!
Depends on the property to be verified
Select topologies: T'
verify topology in T'
Does the
Property
hold ?
yes
PPv=PPv+Ptopo
no
yes
Not verified
topology in T' ?
no
Output: PPv
Alexandre Mouradian - RTNS 13 - 18/10/2013
7 / 12
Verification algorithm
Output: probability that the real-time property holds
Generate logical topologies: T
There are 2N topologies !!!
Depends on the property to be verified
Select topologies: T'
Check that real-time deadline
is met or not on a model of
the network (protocol and topology)
verify topology in T'
Does the
Property
hold ?
yes
PPv=PPv+Ptopo
no
yes
Not verified
topology in T' ?
no
Output: PPv
Alexandre Mouradian - RTNS 13 - 18/10/2013
7 / 12
Case study
f-MAC protocol
Topology
Property
Alexandre Mouradian - RTNS 13 - 18/10/2013
8 / 12
Case study
framelet
f-MAC protocol
data
data
data
data
Topology
Property
Alexandre Mouradian - RTNS 13 - 18/10/2013
8 / 12
Case study
f-MAC protocol
n1
n2
X
X
t'
t1
t2
t'
Topology
Property
Alexandre Mouradian - RTNS 13 - 18/10/2013
8 / 12
Case study
f-MAC protocol
Topology
Topology A
Property
Alexandre Mouradian - RTNS 13 - 18/10/2013
Topology B
8 / 12
Case study
f-MAC protocol
Topology
Property
"All nodes successfuly send a packet to
the sink (node 0) before the deadline"
Alexandre Mouradian - RTNS 13 - 18/10/2013
8 / 12
Network model
1
0
1
1
1
0
0 1 1 1 0
1 0 1 1 1 0
1 0 1 0 1
0 1 11 0 00 1 11 1 01 1 11 0 0
0 1 1 0 0
1 0 00 1111 0010 1101 0100 11 1
1 1 1 0 1
1 1 11 0010 1111 1001 0110 00 0
0 0 0 1 1
1 1 01 1101 1001 1111 0110 10 1
1 0 1 1 1
0 1 11 0100 0110 0110 1111 10 1
0 11 00 10 10 11
0 1 0 1 1 1
0 1 0 1 1
0
1
0
1
1
1
A[] z>deadline imply rcvd==Nn
Alexandre Mouradian - RTNS 13 - 18/10/2013
9 / 12
Verification results
N umber of
nodes
3
4
5
6
N umber of
topologies
8
64
1024
1073741824
N umber of
verified topologies
2
8
64
1024
Alexandre Mouradian - RTNS 13 - 18/10/2013
D uration (s)
A
B
0.30
0.21
0.32
0.33
15.11
15.22
69066.86 69173.25
P pv
A
0.931
0.918
0.875
0.771
B
0.746
0.368
0.323
0.268
10/ 12
Comparison with simulations
Alexandre Mouradian - RTNS 13 - 18/10/2013
11/ 12
Conclusions and future works
Conclusions on the proposed method:
Estimation of topologies probabilities
Timed verification on the topologies
Verification tool independant
Tested with a case study
Alexandre Mouradian - RTNS 13 - 18/10/2013
12/ 12
Conclusions and future works
Conclusions on the proposed method:
Estimation of topologies probabilities
Timed verification on the topologies
Verification tool independant
Tested with a case study
Future works:
Application to a more realistic protocol
Consider asymetric links
Scalability problem ...
Alexandre Mouradian - RTNS 13 - 18/10/2013
12/ 12