CS 672 Paper Presentation

1
CS 672 Paper Presentation
A Survey of Inter-Vehicle Communication Jun
Luo, Jean-Pierre Hubuax EPFL, Switzerland Technica
l Report IC/2004/24
Presented By Saif Iqbal
2
IVC - The Big Picture

• About
• Component of Intelligent Transportation System
  (ITS)
• One of the concrete applications of MANETS
• Attracted research attention in US, EU, and Japan
• Motivation
• Improves road safety and efficiency by increasing
  the horizon of drivers
• and on-board devices
• Transmission of road-side information about
  emergencies, congestion,
• etc.
• Ability for inter-driver communication
• Existing ad hoc networks protocols and
  experiences can actually be put
• to practice

3
IVC - The Big Picture

• Groups Applications
• Association of Electronic Technology for
  Automobile Traffic and
• Driving (JSK), Japan - early 1980s
• CarTALK, EU - 2000
• FleetNet, Germany - 2000
• PATH, California
• Chauffeur, EU
• DEMO 2000, Japan

4
IVC Main Applications
Information and Warning Functions Dissemination
of road information to distant vehicles Communica
tion-based Longitudinal Control Exploiting
look-through capacity to avoid accidents,
platooning vehicles, etc. Co-operative
Assistance Systems Coordinating vehicles at
critical points Added-value Applications Internet
access, Location-based services, Multiplayer
games
5
Paper

• Surveys IVC with respect to key-enabling
  technologies
• Focuses the discussion on the various MAC
  protocols that are really
• important for IVC
• Analyzes application requirements and protocols
  and comes up with
• suggestions with regards to the direction of
  future work
• Does not describe applications, but mentions them
  when their enabling
• mechanisms are discussed

6
Radio Frequency Spectrum

• Both infrared and radio waves have been studied
  and employed
• Radio waves VHF, micro, and millimeter waves
• VHF and microwaves are of broadcast type
• Dedicated Short Range Communication (DSRC) spans
  75MHz of
• spectrum in the 5.9 GHz band
• DEMO 2000, Chauffeur used 5.8 GHz DSRC
• CarTALK, FleetNet use ULTRA TDD
• JSK, PATH, CarTALK have used infrared, typically
  for cooperative
• driving

7
MAC/PHY Layer

• WLAN approach
• 802.11, Bluetooth
• Plus inherent support for distributed
  coordination in ad hoc mode
• Minus low flexibility in radio resource
  assignment and transmission rate
• control
• 3G approach
• CDMA
• Plus high granularity for data transmission and
  flexible assignment of
• radio resources
• Minus complexity in designing the the
  coordination function in ad hoc
• mode

8
WLAN

• Can directly use WLAN standards for RVC, but does
  not work as well
• for IVC
• For migrating to IVC the following problems need
  to be tackled
• -Resistance to more severe multipath effects
• -Time synchronization between rapidly moving
  nodes
• -Distributed resource allocation
• Token Ring Protocol - PATH
• Mechanism to construct, recover, join, and leave
  a ring
• Token circulation, recovery, and multiple token
  resolution
• Solves contention for radio resources
• Need further experiments to see if this suitable
  for IVC

9
WLAN

• Location-based Channel Access (LCA)
• Divides the geographical area into cellular
  structure
• Each cell has a unique channel associated with it
• Any multiple access scheme like CSMA, CDMA, TDMA
  can be used
• within the cell
• Adaptability to high mobility in IVC is a
  question mark
• Non-Persistent CSMA DOLPHIN/DEMO 2000
• DOLPHIN Dedicated Omni-purpose inter-vehicle
  communication
• Linkage Protocol for Highway Automation
• Non-persistent CSMA outperforms p-persistent one
  with respect to
• packet loss in IVC

10
3G

• Cannot directly employ it as it is meant for
  centralized cellular networks
• For extending to IVC the following problems need
  to be addressed
• -Distributed radio resource management
• -Power control algorithms
• -Time synchronization
• Solution should rely on distributed media access
  control
• Reservation ALOHA CarTALK/FleetNet
• Use R-ALOHA for distributed channel assignment
• High throughput, as a node which catches a slot
  can use it in subsequent
• frames as long as it has packets to send
• Frequent reservation attempts due to short packet
  trains
• Due to hidden terminal problem, destructive
  interference with
• established channels may occur
• Reliable R-ALOHA lets all nodes know the status
  of the slots

11
3G

• Random Access CDMA
• Combines CDMA with random channel access start
  transmission
• immediately irrespective of the state of the
  channel
• Can avoid primary collisions (two nodes with the
  same code try to
• access the channel together) using code
  assignment, spread-coding
• schemes
• Multi-access interference (MAI) results in
  secondary collisions (near-far
• problem) at the receiver
• Controlled Access CDMA
• Uses a modified RTS/CTS mechanism to solve the
  problem
• Split the channel for control and data RTS/CTS
  is transferred over
• control channels to let the interfering nodes be
  aware of the status
• Use knowledge of power levels to alleviate the
  near-far problem

12
MAC/PHY Layer

• Summary
• Number of MAC protocols proposed, but not all of
  them are put into
• practice
• 802.11b is used for demonstration (FleetNet)
• 802.11a is chosen by ASTM (American Society for
  Testing and
• Materials) as the basis for DSRC
• MAC Protocol based on ULTRA TDD, used in CarTALK,
  could be
• another solution especially in the EU

13
Network Layer

• Any existing position-based routing protocol for
  ad hoc networks can be
• applied to IVC
• Can optimize by using location and surrounding
  awareness information
• Mostly group-oriented communications rather than
  pair-wise
• Unicast Routing
• Contention-Based Forwarding
• Proposes a forwarding scheme avoiding the use of
  beacons and hence
• higher efficiency
• Reactive Location Service - FleetNet
• Reactive routing protocol by requesting the
  location of the destination
• when sending a packet
• Afterwards, a greedy geographical forwarding
  technique is used

14
Network Layer

• Broadcast Routing
• Used to disseminate traffic information
• Can be made adaptive change the
  inter-transmission interval
• Use a randomized interval
• Multi-resolution data structure to express
  information in the message
• Summary
• Unicast routing is superfluous in most cases
• Broadcast routing seems to be a necessary
  supporting mechanism of
• IVC applications
• Broadcast routing could also be optimized in
  various ways

15
Group Communication

• Group communication primitives are important as
  reliability required for
• critical situations, where group information
  dissemination may not work
• Required by two important applications
  platooning and cooperative
• driving
• Localized Group Membership Service (LGMS)
• Reduce the group membership service to the local
  environment of a
• node
• Only tracks memberships of neighbors and installs
  a local view at each
• node
• Works for congestion area detection
• Does not support any functions with reliability
  requirement due to lack
• of a global view of the group

16
Group Communication

• Event-based middleware
• Supports cooperative mobile applications
• Underlying membership service is costly and not
  really needed
• Implemented only on RVC scenarios
• The Driving Philosopher Problem
• Sharing resources among a group of vehicles
• Proposed algorithm solves the model in a
  synchronous model
• Impossible to achieve fairness and concurrency at
  the same time
• Impossible to solve the problem in an
  asynchronous model
• Summary
• Important component of IVC
• Build the system directly upon the MAC layer
• Lightweight membership tracking instead of doing
  it globally

17
Security

• Driver Ad Hoc Networking Infrastructure (DAHNI)
• System mounted on each vehicle which includes
  both processing and
• wireless communication facilities
• Each car constitutes a local communication
  network around itself
• Come to the conclusion that no confidentiality is
  needed, and ignore
• privacy concerns
• To securely estimate the distance between
  vehicles, establishment of
• symmetric keys is required
• Electronic License Plates
• Certified identity that a vehicle provides via a
  wireless link
• Usage Dynamic toll charge, identify culprits,
  distance estimation
• Attacks Disable system, impersonation, denial of
  service
• Supports cooperative driving

18
Security

• Summary
• Security of IVC has been ignored so far by the
  research community
• Some ideas proposed but not followed through and
  implemented
• Emerging and potentially important research topic

19
Mobility Model

• Mobility pattern in IVC is quite different from
  the random waypoint
• model used for ad hoc networks simulation
• Simulations for MAC protocols should also take
  mobility into account
• which is not necessarily the case with
  traditional MAC
• There are proposed tools for traffic simulation
  to help extend the
• network simulators
• Application context has to be taken into account
  before choosing a
• mobility model to evaluate certain protocols
• Mathematical Modeling for Traffic
• Microscopic suitable for simulating group
  communications
• Macroscopic for routing protocols discussion
• Statistical real mobility pattern is in 2-d or
  3-d space, approach based
• on Markov chain theory

20
Conclusion

• Design of communication protocols in IVC is
  extremely challenging
• Ad hoc routing protocols, and group communication
  primitives
• migrated from wired networks might not be
  efficient
• Most of the proposed work is in routing
  algorithms and MAC
• Routing protocols are unnecessary in most cases
• Local distributed coordination functions sitting
  directly upon the
• MAC would be more efficient
• As vehicles become smarter, security and
  privacy gain importance
• Mathematical models for road traffic are
  important for simulations