V2V applications:End to end or broadcast-based?
Panel
VANET 2007, Sept 10, 2007
Mario Gerla
Computer Science Dept, UCLA
www.cs.ucla.edu
End to end vs broadcast based
• VANET E2E networking (without infrastructure) extremely challenging:– An urban VANET may have over 100,000 nodes– Nodes move in unpredictable ways– End to end routing is HARD
• AODV and OLSR do not scale• Geo-routing can get trapped in “dead ends”• Geo Location Service not very scalable
– TCP over several hops “in motion” is a nightmare!– Intermittent connectivity in most cases
• So, end to end applications (a la mesh network) hard to deploy
• However….
Where are the E2E applications?
• Very few urban scenarios/applicatios require “true” E2E networking:
– Emergency, disaster recovery (eg, earthquake, hostile attack)
– Urban warfare
• Generally, these are situations where the Infrastructure has failed
PowerBlackout
STOP
PowerBlackout
STOP
Broadcast based applications
• The most popular VANET applications are “broadcast” based– Safe navigation - neighborhood broadcast– Content sharing - P2P proximity routing– Distributed urban sensing - Epidemic dissemination
Car to Car broadcast for Safe Driving
Vehicle type: Cadillac XLRCurb weight: 3,547 lbsSpeed: 65 mphAcceleration: - 5m/sec^2Coefficient of friction: .65Driver Attention: YesEtc.
Vehicle type: Cadillac XLRCurb weight: 3,547 lbsSpeed: 45 mphAcceleration: - 20m/sec^2Coefficient of friction: .65Driver Attention: NoEtc.
Vehicle type: Cadillac XLRCurb weight: 3,547 lbsSpeed: 75 mphAcceleration: + 20m/sec^2Coefficient of friction: .65Driver Attention: YesEtc.
Vehicle type: Cadillac XLRCurb weight: 3,547 lbsSpeed: 75 mphAcceleration: + 10m/sec^2Coefficient of friction: .65Driver Attention: YesEtc.
Alert Status: None
Alert Status: Passing Vehicle on left
Alert Status: Inattentive Driver on Right
Alert Status: None
Alert Status: Slowing vehicle aheadAlert Status: Passing vehicle on left
Co-operative Download: Car Torrent
Vehicle-Vehicle Communication
Internet
Exchanging Pieces of File en route
Accident Scenario: storage and retrieval
• Designated Cars (eg, busses, taxicabs, UPS, police agents, etc): – 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)– Epidemically disseminate -> distributed index
• Police retrieve data from designated cars
Meta-data : Img, -. (10,10), V10
CRASH
- Sensing - P rocessing
Crash Summary Reporting
Summary Harvesting
Epidemic Diffusion - Idea: Mobility-Assist Meta-Data Diffusion
Epidemic Diffusion - Idea: Mobility-Assist Meta-Data Diffusion
1) “periodically” Relay (Broadcast) its Event to Neighbors 2) Listen and store other’s relayed events into one’s storage
Keep “relaying” its meta-data to neighbors
Epidemic Diffusion - Idea: Mobility-Assist Meta-Data Harvesting
Meta-Data Req
1. Agent (Police) harvestsMeta-Data from its neighbors
2. Nodes return all the meta-datathey have collected so far
Meta-Data Rep
The Future
• Future VANET applications will be broadcast, proximity routing based
• However, proximity and broadcast only removes the E2E complexity
• Enormous challenges still ahead:• Navigation safety
– “liability” stigma– strict delay constraints
• Location aware content, Infotainment– Driver distraction -> more accidents?– Virus scare
• Urban Sensing– Business model not clear (who makes money?)– Privacy issues
Thank You