Remote Deployment of Sensor Networks

1
Remote Deployment of Sensor Networks

• Case Study Monitoring the mountains of
  Afghanistan

2
Context

• Military monitoring of Oppositional Forces in
  remote, inaccessible areas like the mountains of
  Afghanistan and Pakistan using wireless sensor
  networks.
• The deployment and uplink methods in this
  application are largely unexplored

3
Kyber Pass One of the more accessible roadways
in this part of the world, rarely used by
guerilla fighters
4
Main Problems

• Wireless sensor networks still require (in most
  applications)
• Manual (even if random) placement of nodes
• Infrastructure at head end
• These obstacles must be overcome to deploy a
  monitoring network readily in the target
  environment

5
Issues outlined today

• Distribution method (hands-off)
• Data aggregation, sensor configuration
• Uplink strategy (no infrastructure)
• Network management
• Energy optimization
• Security
• Final Goals

6
Distribution Methods
GOOD Takes ground personnel out of dangerous or
hostile-controlled terrain BAD Result in very
poorly-behaved, random distributions wind
currents or terrain features may cause many
sensors to channel into a ravine, or
riverBallistics and delivery will not be a main
focus of this research
Air-scatter, Air-dropLikely conducted at night
to avoid detection
Multiple Launch Rocket System
7
Distribution Package
Smart Dust or bigger motes could be dropped at
altitude as a bundle with parachute then
scattered at low altitude to control distribution
area
Smart dust is great for military applications
because it is small (appx 1mm), difficult to
detect, can be dropped at high altitude
Motes could be disguised as rocks
8
Data, Sensors The Target
Trucks, horses, pedestrians
Seismic, audio, heat, visual, chemical,
electromagnetic signatures
9
Data, Sensors Sensor Devices

• Heterogeneous approach multiple types of
  sensors, nodes
• Since life of network is dependent on
  functionality of many types of nodes, lifetime
  and failure calculations become more complex

10
Data, Sensors Sensor Devices

• Use passive or low power sensors as
  first-responders (piezoelectrics like audio,
  seismic)
• The first-responder sensors will wake up
  neighboring nodes with other sensors (thermal,
  visual, electromagnetic, chemical, radiological,
  etc)
• Power-hungry sensors should sleep as much as
  possible

11
Uplink Heterogeneous Nodes

• Connect to military satellite constellation
• Uplink nodes will be different from sensor nodes
  larger, more battery, more power
• Uplink nodes form some small of all nodes

12
Uplink Initialization
?
How to initialize the network when the head is
seen as being in multiple places? How to avoid
partitioning? This will be researched and
protocol developed.
13
Network Expendable Uplinks
Active
14
Network Expendable Uplinks
POWER LOW
Active
TAKE OVER
15
Network Expendable Uplinks
Active
One can see this rerouting may be computation
intensive, and is in fact similar to MANET
routing when nodes fail. The main difference
here the network can still be operational if it
is partitioned.
16
Network Protocols

• A significant undertaking of the project is to
  develop and simulate the protocol which reassigns
  the network head in an energy efficient manner
  for various configurations
• Important to optimize whole network power
  consumption

17
Network Protocols

• Routing must transition to avoid periods of
  downtime or routing confusion
• Current head node must select its successor to
  eliminate routing confusion

18
Energy Lifetime

• Network needs to be operational for at least a
  few months at a time otherwise satellite
  monitoring becomes preferable in some
  circumstances
• The heterogeneous nodes will have to adapt to
  over-stimulus to keep network alive. i.e. if
  animals constantly pass by the network and trip
  seismic sensors, they should be able to be
  ignored in favor of reliable detectors like
  electromagnetic

19
Security

• Primary risk is detection of presence not data
  decoding
• Spread spectrum, noise-like signals should be
  used
• Chatter must be kept to minimum
• Alert uplinks are okay

20
Security

• The network may be compromised by several means
• Stimulate for false positives, perhaps rapidly
  depleting the network of energy
• Compromise the uplink signal/device
• Jamming

21
Security Countermeasures

• Detect, isolate, ignore false-positive flood
  input
• Encode uplink transmission
• Spread spectrum jam resistant communications
  links

22
Goals

• Develop basic application proposal for DARPA SBIR
• Identify one narrow topic within the system which
  needs research and development, write a paper on
  that topic
• Current candidate for narrow researchprotocol
  to identify, shift network head-ends

23
Conclusions

• Next lecture will involve the analysis of key
  challenges, quantitative approaches, and outline
  of the draft proposal for DARPA