SAFIRENET: Next-Generation Networks for Situational Awareness

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SAFIRENET Next-Generation Networks for
Situational Awareness

• Nalini Venkatasubramanian

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Situational Awareness for Firefighters
Questions to be answered Where are the
firefighters? Are they doing well? Any danger?
Deliver contextual data sensed by firefighters to
the incident commander
Challenges
Limited infrastructure access
High network deployment cost
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Motivation

• Multitude of technologies
• WiFi (infrastructure, ad-hoc), WSN, UWB, mesh
  networks, DTN, zigbee
• SAFIRE Data needs
• Timeliness
• immediate medical triage to a FF with significant
  CO exposure
• Reliability
• accuracy levels needed for CO monitoring
• Limitations
• Resource Constraints
• Video, imagery
• Transmission Power, Coverage,
• Failures and Unpredictability
• Goal
• Reliable delivery of data over unpredictable
  infrastructure

Information need
DATA
NEEDS
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Experiences with Existing Network Technologies

• Lessons Learned Despite multitudes of
  technologies, rapidly deployable,
  self-configuring networks that provide end-to-end
  continuous connectivity are hard to create!!!

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Experiences in deploying WiFi Mesh
Commercial mesh routers not good enough
5X improvement with new antenna
technology Better signal coverage better building
penetration

• Some Setup effort required
• Not always feasible
• Vulnerable to hardware failures

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SAFIRE Mote Sensor Deployment
Heart Rate
Crossbow MIB510 Serial Gateway
Crossbow MDA 300CA Data Acquisition board on
MICAz 2.4Ghz Mote
Inertial positioning
IEEE 802.15.4 (zigbee)
To SAFIRE Server
Carbon monoxide
Temperature, humidity
Carboxyhaemoglobin, light
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Experiences in deploying mote sensors and Zigbee
networks
?Mobility?Reliability Network convergence,
gateway availability
Calibration is essential
static
Frequency matters!!
mobile
?Density?Reliability

Topology matters!!
?Size?Reliability
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(Un) Reliability of Wi-Fi Networks
Ad-hoc 1hop gt Ad-hoc 2 hops gt Private AP gtgtgt
Public AP

• No background traffic
• Controllable configuration

• Increased bandwidth share
• Reduced contentions/collisions

• Less interferences
• Distributed Beaconing

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Creating Reliable Networks for Onsite
Communication

• Goal Enabling Robust, Timely Data Transfer by
  combining technologies

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Approaches

• Exploit multiple networks that together provide
  connectivity (Mobiquitous 2005, WCNC 2007,
  INFOCOM 2009)
• WiFi mesh direct connectivity to a mesh router
• MANETS hop by hop connectivity to gateway nodes
• Zigbee adhoc connect to WiFi backbone through
  gateway node
• Exploit mobility when disconnected
• Store-and-forward networks (Delay Tolerant
  Networking)
• mobile nodes ferry data to gateway node
• Combine connected network clouds and disconnected
  networks

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Reliable Content Delivery in Connected Networks

• Two aspects Data delivery, message awareness
• RADCAST Flash Broadcast in MANETS (Infocom 2009,
  Percom 2009)
• Concurrent dissemination of awareness and content
• Data diffusion based on a mix of push/pull
  (Pryer)
• Awareness assurance network traversal using
  walkers (Peddler)
• Problem fast network traversal (NP-hard)
• Minimizing cover time, termination time and
  transmission overhead

Assures reception

Walker
Metadata

Awareness Assurance
concurrent
Reliable Content Dissemination
Walker
Guides
Fragmentation
Retrieves missing
concurrent

Pull
Content Data
Data Diffusion
concurrent
Push
Spreads
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Supporting Varying Reliability Needs in Connected
Networks
Reliability Level Reliability Needs Awareness Assurance Data Diffusion Network Size Knowledge Cost
Max All reachable nodes receive the content v v Ignore High
Lower-Bounded A specified number of nodes are guaranteed to receive the content v v Exploit Medium
Best-Effort As many nodes as possible receive the content, no guarantee is required v N/A Low
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Situational Awareness in a disconnected
environment
Periodically sensing e.g., WiFi AP fingerprints,
accelerometer readings, residue battery,
snapshots, audio/video recording, etc.
A Store-Move-and-Forward (DTN) based approach
Easy deployment of one or several mesh routers at
the edge of the area
Forward bundles upon device encounters
Forward bundles upon gateway encounters
Incident Commander Board
Aggregate contextual data
Visualizing the task execution process spatially
and temporally
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The Store-and-Forward Data Transfer Problem

• Each device maintains a cache storing bundles
  from itself and others
• Devices exchange certain bundles in cache upon
  encounters

• High reliability
• Low storage cost
• Low transmission cost
• Short latency

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Store-and-Forward Data Transfer Solution Overview
Components
Strategies
Modeling

Fixed Number of Distinct Copies
Replication
Context Sens- ing Collection
Location- Closeness Based
Task Scheduling
Forwarding
Aliveness-Signi- ficance Based
0-1 Knapsack
Purging
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Implementation on Mobile Devices
Emergency Situ-ational Awareness
Flash Broadcast
RADcast
Maemo
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Note Reliable networks ?Reliable Data Collection

• Sensing Errors Occur
• Visibility Readings vary
• Occlusions etc.
• Spikes in SpCO readings due to FF movement
• Read errors due to misaligned sensor strip
• Reliability at application level is also needed
  needed
• Sensor Calibration (MMCN08)
• Heart-rate, CO exposure
• Exploitation of Semantics, prediction
• Exploit application tolerance to errors