Vehicle communications: from P2P networks to sensor platforms Taiwan May 11, 2006

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Vehicle communications from P2P networks to
sensor platforms TaiwanMay 11, 2006

• Mario Gerla
• Computer Science Dept
• UCLA

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Outline

• Ad Hoc Wireless Networks
• Vehicle Communications
• Car Torrent
• Ad Torrent
• Cars as mobile sensor platforms

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The three mobile wireless waves

• Wave 1 cellular telephony (1980)
• Still, biggest profit maker
• Wave 2 wireless Internet access (1995)
• WiFI, WIMAX standards
• Most Internet access on US campuses is wireless
• Hot spots are rapidly proliferating in the US
  Europe and Asia to follow soon
• Cellular providers (2.5 G and 3G) are trying to
  keep up
• Wave 3 ad hoc wireless nets (now)
• Set up in an area with NO infrastructure to
  respond to a specific, time limited need

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The 3rd wave Infrastructure vs Ad Hoc
Infrastructure Network (WiFI or 3G)
Ad Hoc, Multihop wireless Network
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Ad Hoc Network Characteristics

• Instantly deployable, re-configurable (No fixed
  infrastructure)
• Created to satisfy a temporary need
• Portable (eg sensors), mobile (eg, cars)
• Multi-hopping ( to save power, overcome
  obstacles, etc.)

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Typical Ad Hoc Network Applications

• Military
• Automated battlefield
• Civilian
• Disaster Recovery (flood, fire, earthquakes etc)
• Law enforcement (crowd control)
• Homeland defense
• Search and rescue in remote areas
• Environment monitoring (sensors)
• Space/planet exploration

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SATELLITE
COMMS
SURVEILLANCE

MISSION
UAV-UAV NETWORK
COMM/TASKING
COMM/TASKING
Unmanned
UAV-UGV NETWORK
Control Platform
COMM/TASKING
Manned
Control Platform
Typical Ad Hoc Network
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Traditional ad hoc nets

• Civilian emergency, tactical applications
• Instant deployment
• Infrastructure absent (so, must recreate it)
• Specialized missions (eg, UAV scouting)
• Critical scalability, survivability, QoS, jam
  protection
• Non critical Cost, Standards, Privacy

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New Trend Opportunistic ad hoc nets

• Commercial applications
• Indoor W-LAN extended coverage
• Group of friends sharing 3G via Bluetooth
• Peer 2 peer networking in the vehicle grid
• Cost is a major issue
• Access to Internet available, but
• bypass it with ad hoc if too costly or
  inadequate
• Critical Standards -gt cost reduction and
  interoperability
• Critical Privacy, security

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Urban opportunistic ad hoc networking
From Wireless to Wired network Via Multihop
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Car to Car communications for Safe Driving
Vehicle type Cadillac XLRCurb weight 3,547
lbsSpeed 65 mphAcceleration -
5m/sec2Coefficient of friction .65Driver
Attention YesEtc.
Vehicle type Cadillac XLRCurb weight 3,547
lbsSpeed 75 mphAcceleration
20m/sec2Coefficient of friction .65Driver
Attention YesEtc.
Alert Status None
Alert Status None
Alert Status Inattentive Driver on Right
Alert Status Slowing vehicle ahead
Alert Status Passing vehicle on left
Vehicle type Cadillac XLRCurb weight 3,547
lbsSpeed 45 mphAcceleration -
20m/sec2Coefficient of friction .65Driver
Attention NoEtc.
Vehicle type Cadillac XLRCurb weight 3,547
lbsSpeed 75 mphAcceleration
10m/sec2Coefficient of friction .65Driver
Attention YesEtc.
Alert Status Passing Vehicle on left
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Opportunistic piggy rides in the urban mesh
Pedestrian transmits a large file block by block
to passing cars, busses The carriers deliver the
blocks to the hot spot
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DSRC / IEEE 802.11p Vehicle Grid Enabler

• Car-Car communications at 5.9Ghz
• Derived from 802.11a
• three types of channels Vehicle-Vehicle service,
  a Vehicle-Gateway service and a control broadcast
  channel .
• Ad hoc mode and infrastructure mode
• 802.11p IEEE Task Group for Car-Car
  communications

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DSRC Channel Characteristics
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CarTorrent Opportunistic Ad Hoc networking to
download large multimedia files

• Alok Nandan, Shirshanka Das
• Giovanni Pau, Mario Gerla
• WONS 2005

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You are driving to VegasYou hear of this new
show on the radioVideo preview on the web (10MB)

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One option Highway Infostation download
Internet
file
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Incentive for opportunistic ad hoc networking

• Problems
• Stopping at gas station for full download is a
  nuisance
• Downloading from GPRS/3G too slow
  and quite expensive
• Observation many other drivers are interested in
  download sharing (like in the Internet)
• Solution Co-operative P2P Downloading via
  Car-Torrent

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CarTorrent Basic Idea
Internet
Download a piece
Outside Range of Gateway
Transferring Piece of File from Gateway
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Co-operative Download Car Torrent
Internet
Vehicle-Vehicle Communication
Exchanging Pieces of File Later
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BitTorrent. A picture..
Uploader/downloader
Uploader/downloader
Uploader/downloader
Tracker
Uploader/downloader
Uploader/downloader
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CarTorrent Gossip protocol
A Gossip message containing Torrent ID, Chunk
list and Timestamp is propagated by each peer
Problem how to select the peer for downloading
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Selection Strategy Critical
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Car Torrent with Network Coding

• Limitations of Car Torrent
• Piece selection critical
• Frequent failures due to loss, path breaks
• New Approach network coding
• Mix and encode the packet contents at
  intermediate nodes
• Random mixing (with arbitrary weights) will do
  the job!

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Network Coding
e e1 e2 e3 encoding vector tells how packet
was mixed (e.g. coded packet p ?eixi where xi
is original packet)
buffer
Receiver recovers original by matrix inversion
random mixing
Intermediate nodes
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Simulation Results
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Simulation Results 2
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AdTorrent Digital BillBoards for Vehicular
Networks

• V2V COM Workshop
• Mobiquitous 2005
• WONS 2006
• Alok Nandan, Shirshanka Das
• Biao Zhou, Giovanni Pau, Mario Gerla

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Digital Billboard

• Safer Physical billboards can be distracting to
  drivers
• Less intrusive The skyline is not marred by
  unsightly boards.
• Efficient With a filter on the client
  (vehicle) side, users will see the Ad only if
  they actively search for it or are interested in
  it.
• Localized The physical wireless medium
  automatically induces locality characteristics
  into the advertisements.

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Digital Billboard

• Every Access Point (AP) disseminates Ads that are
  relevant to the proximity of the AP
• Passing cars pick up the Ads
• What is an Ad?
• simple text message
• trailer of nearby movies,
• virtual tour of hotels etc
• Business owners in the vicinity subscribe to this
  digital billboard service for a fee.

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AdTorrent Features

• Keyword Set Indexing to reduce Communication
  Overhead
• Epidemic Query Dissemination optimized for
  vehicular ad hoc setting
• Swarming of actual content delivery
• Discourage Selfishness

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Hit Rate vs. Hop Count Cache
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Vehicular Sensor Network (VSN)PerSens
2006Uichin Lee, Eugenio Magistretti (UCLA)
1. Fixed Infrastructure 2. Processing and
storage
Infostation
Car to Infostation
1. On-board black box 2. Processing and
storage
Car-Car multi-hop
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Vehicular Sensor Applications

• Environment
• Traffic congestion monitoring
• Urban pollution monitoring
• Civic and Homeland security
• Forensic accident or crime site investigations
• Terrorist alerts

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Accident Scenario storage and retrieval

• Designated Cars
• Continuously collect images on the street (store
  data locally)
• Process the data and detect an event
• Classify the event as Meta-data (Type, Option,
  Location, Vehicle ID)
• Post it on distributed index
• Police retrieve data from designated cars

Crash!
Meta-data Img, -. (10,10), V10
Meta-data Img, Crash, (10,5), V12
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How to retrieve the data?

• Epidemic diffusion
• Mobile nodes periodically broadcast meta-data of
  events to their neighbors
• A mobile agent (the police) queries nodes and
  harvests events
• Data dropped when stale and/or geographically
  irrelevant

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Epidemic Diffusion - Idea Mobility-Assist Data
Diffusion
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Epidemic Diffusion - Idea Mobility-Assist Data
Diffusion
1) periodically Relay (Broadcast) its
Event to Neighbors 2) Listen and store
others relayed events into ones storage
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Epidemic Diffusion - Idea Mobility-Assist Data
Harvesting

• Agent (Police) harvestsMeta-Data from its
  neighbors
• Nodes return all the meta-datathey have
  collected so far

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VSN Mobility-Assist Data Harvesting (cont)

• Assumption
• N disseminating nodes each node ni advertises
  event ei
• k-hop relaying (relay an event to k-hop
  neighbors)
• v average speed, R communication range
• ? network density of disseminating nodes
• Discrete time analysis (time step ?t)
• Metrics
• Average event percolation delay
• Average delay until all relevant data is harvested

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Simulation Experiment

• Simulation Setup
• NS-2 simulator
• 802.11 11Mbps, 250m tx range
• Average speed 10 m/s
• Mobility Models
• Random waypoint (RWP)
• Real-track model
• Group mobility model
• merge and split at intersections (RT)
• Westwood map

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Data harvesting delay with RWP
Agent
Regular Nodes
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Harvesting results with Road Tracks
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Conclusions

• Vehicular Grid new applications
• Dynamic content sharing/delivery
• Car Torrent , Ad Torrent
• Pervasive, mobile sensing
• Research Challenges
• New routing/transport models epidemic, P2P
• Searching massive mobile storage
• Security, privacy, incentives
• Our Future Research
• Car torrent linux implementation testbed
  deployment
• Interconnection with the Internet
• Car 2 Car network games

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Related Projects

• UMassDiesel (UMass)
• A Bus-based Disruption Tolerant Network (DTN)
• http//signl.cs.umass.edu/diesel
• VEDAS (UMBC)
• A Mobile and Distributed Data Stream Mining
  System for Real-Time Vehicle Monitoring and
  diagnostics
• http//www.cs.umbc.edu/hillol/vedas.html
• CarTel (MIT)
• Vehicular Sensor Network for traffic conditions
  and car performance
• http//cartel.csail.mit.edu
• RecognizingCars (UCSD)
• License Plate, Make, and Model Recognition
• Video based car surveillance
• http//vision.ucsd.edu/car_rec.html

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The End

• Thank You