1. A simple data-muling protocol**
Pablo Basanta Val
Marisol García-Valls
Miguel Baza-Cuñado
http://www.it.uc3m.es/drequiem/
**Accepted in IEEE Transactions on Industrial informatics (I.F.: 3.1).

2. Outline
• Introduction
• The D&U Data-Muling Protocol
– Constraints &Model
– Discovery and Updates
• D&U Evaluation
– Mote characterization
– Benchmark Results
• Conclusions
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3. Introduction
• Traditional industrial infrastructures were wired
– There a trend towards wireless infrastructures (IWSNs)
– Future industrial infrastructures would be hybrid
(wired+wireless)
• In addition to wired and wireless, infrastructures may
extend wired and wireless with data-muling
– To have a more flexible infrastructure
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4. Wired, Wireless and Data-Muling
in an Industrial Infrastructure
• Potentiality:
– Versatility in supporting different applications
– Data-muling in industrial infrastructures (e.g. a train) is more
predictable than in general (random muling behaviour of people)
scenarios
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5. Some challenges for industrial datamuling
[CH1]
Resource constraints related to energy, memory and CPU
- Mules and motes may have energy constraints and run on embedded
devices
[CH2] Topology problems and environmental issues.
- Networks that appear and disappear dynamically
[CH3] Quality of service requirements
[CH4] Redundancy
[CH5] Security
[CH6] Deployment and ad-hoc integration
[CH7] Internet integration.
- Access from other higher order networks
This work is mainly concerned with CH1 CH2 and CH7.
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6. D&U Data Mulling Protocol
Bounds and Limitations
• Actors: 1) motes, 2) host nodes and 3) the mules
• Communications
– Intermittent communications and no direct vision among different motes
• Energy constraints
– In the mule but not in the motes (they have a supply source)
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7. D&U Data Mulling Protocol
The protocol
• Periodically, the mote looks for other nodes with sleep periods
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8. D&U Data Mulling Protocol
Node Discovery subprotocol
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9. D&U Data Mulling Protocol
Basic Data Update (of b and a) in the D&U protocol
• Two steps for downloading data:
– Clock synchronization for each mule to mote interaction
– Data transmission
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10. D&U Data Mulling Protocol
data model
• Communication model:
-A distributed data table with motes that read and write data
-Synchronized by the mule
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11. D&U Data Mulling Protocol
Data freshness
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12. Implementation
hardware
• The mule and the mote run the same hardware
– On Java’s SunSPOT
– Software modified to run more efficiently
Description
CPU ARM920T -32 bits (ARMv4) at 180MHz
Memory S71PL032J40 Mem
512 KBytes pSRAM and
4 Mbytes NOR Flash
Network
Battery
I/O
ports
TI CC2420 at 2,4 GHz (IEEE 802.15.4)
Li-ION de 3,7V (720 mAh)
1 x USB 1.1/2.0, 2 x UARTs,
5 x general purpose I/O Ports
802.15.4 Tx pot.=-3dbm and freq 26 (2480 Mhz)
setup Max transmission distance= 10 meters
API Clock access and battery access via API
facilities Send/Receive data via connections or
diffusion (802.15.4)
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Energy model of the mote
Mode
Consumption
(mAh)
70-120 mAh
24 mAh
Run mode
Shallow-sleep
mode
Deep sleep mode 32 µAh
Mote Wakeup
70-120 mAh
time
Duration
6-10 hours
30 hours
22500 hours
10 ms (max)
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13. Implementation
software stack and protocols
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14. Empirical evaluation
General issues
Based on the iLAND project and other
internal real-time Java benchmarks
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15. Empirical evaluation
Mote characteristics: data rate and energy costs
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16. Empirical evaluation
Mote characteristics: mule speed
• The maximum update time in ideal conditions
- clocks perfectly synchronized
- Mote detected as soon as the mote is in the 10
meters range.
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17. Empirical evaluation
Mote characteristics: maximum data transferred
• non-feasible area
– 1 mote and 1 mule at 330
km/h
– 128 motes with a mule at
5km/h.
• Original vs. D&U protocol
– 25% of additional motes
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18. Empirical evaluation
Mote characteristics: battery profile
• With (TIUmin=1 hour) and
(TIDmin=1 second)
– 18000 hours of operation
– Ideal data-mulling add 15% of
energy
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19. Benchmark
Memory in the mule
• Infeasibility area
- 512 bytes sampling period
of 2.5 minutes
- with 1 byte and 10
milliseconds)
• Idealized version may add
100% to 190% additional
motes
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20. Benchmark
Time in the mule
• Feasibility area
– 1byte-2us intra period
– 512 bytes-2 ms intra period
range
• With an idealized protocol
you may add 20% to 190%
more motes
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21. Benchmark
Energy in the mule bound
• The mule may recharge in
each round
• Infea
• sibility area
- [1 byte each 3µs]
- [512 bytes each second]
• The Ideal data-muling
protocol improves by 25% to
197%
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22. Conclusions and ongoing work
• Proposed a new communications protocol
– Called the D&U protocol that runs on IEEE
802.15.4
• Evaluation results highlight the importance of
having save energy strategies
– Identified an idealized protocol
• Ongoing work
– To extend this results to other protocols
– E.g. 802.11 and DPWS, UPnP
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23. http://www.it.uc3m.es/drequiem/
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