Adaptive Carrier Sense Mechanism in Safety Vehicular Ad-hoc Networks - - PowerPoint PPT Presentation

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Adaptive Carrier Sense Mechanism in Safety Vehicular Ad-hoc Networks - - PowerPoint PPT Presentation

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Adaptive Carrier Sense Mechanism in Safety Vehicular Ad-hoc Networks Razvan Stanica, Emmanuel Chaput, Andr-Luc Beylot University of Toulouse Institut de Recherche en Informatique de Toulouse IVN Exploratory Seminar INRIA Rocquencourt - 15

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Adaptive Carrier Sense Mechanism in Safety Vehicular Ad-hoc Networks

University of Toulouse Institut de Recherche en Informatique de Toulouse IVN Exploratory Seminar INRIA Rocquencourt - 15 December 2011

Razvan Stanica, Emmanuel Chaput, André-Luc Beylot

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Adaptive Carrier Sense Mechanism in Safety VANETs

 Safety Communication in Vehicular Networks  Particularities of the VANET Control Channel  The Importance of the Carrier Sense Range  Adaptive Carrier Sense Threshold

Razvan Stanica University of Toulouse IVN 2011

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Adaptive CS Safety V2V Carrier Sense Range

VANET objective: Building an accurate image of the exterior world  Cooperative Awareness Message (CAM)  Decentralised Environmental Notification (DEN)

Control Channel Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Control Channel Adaptive CS Carrier Sense Range

 Intersection Collision Warning  Emergency Electronic Brake Lights  Approaching Emergency Vehicle  Lane Change Assistant  Left-Turn Collision Warning

Safety Applications

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V

5.860 5.870 5.880 5.890 5.900 5.910 5.920 G5SC4 G5SC3 G5SC1 G5SC2 G5CC CH172 CH174 CH176 CH178 CH180 CH182 CH184 USA Spectrum Allocation Europe Spectrum Allocation  Service channels (SCH) – non-safety (usually IP-based) applications  Control channel (CCH) – safety applications

Control Channel Adaptive CS Carrier Sense Range Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Control Channel

Safety beaconing

 A beacon expires if the next CAM is produced  No exposed terminals  Practically no internal contention on the CCH  MAC delay automatically considered in the expiration probability  Metric of interest: reception probability

Adaptive CS Carrier Sense Range Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Control Channel

IEEE 802.11p on the CCH

Adaptive CS Carrier Sense Range

100% broadcast communication No ACK message Collisions can not be detected BEB mechanism deactivated Always use the minimum value for CW

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Control Channel

Congestion Control

 Reduce Beaconing Frequency

Adaptive CS Carrier Sense Range Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Control Channel

Congestion Control

 Reduce Beaconing Frequency  Increase Data Rate

Adaptive CS Carrier Sense Range Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Control Channel

Congestion Control

 Reduce Beaconing Frequency  Increase Data Rate  Control Transmission Power

Adaptive CS Carrier Sense Range Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Control Channel

Congestion Control

 Reduce Beaconing Frequency  Increase Data Rate  Control Transmission Power  Modify Back-off Mechanism

Adaptive CS Carrier Sense Range Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Control Channel

Congestion Control

 Reduce Beaconing Frequency  Increase Data Rate  Control Transmission Power  Modify Back-off Mechanism  Adapt Carrier Sensing

Adaptive CS Carrier Sense Range Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Carrier Sense Range Control Channel Adaptive CS

Carrier Sense in IEEE 802.11

 MAC Layer – Network Allocation Vector

  • based on the RTS/CTS handshake
  • unusable on the broadcast CCH

 PLCP Layer – Clear Channel Assignment

  • header detection
  • energy detection

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Carrier Sense Range Control Channel Adaptive CS

Carrier Sense Range

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Carrier Sense Range Control Channel Adaptive CS

Carrier Sense Range Safety Range

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Carrier Sense Range Control Channel Adaptive CS

Carrier Sense Range Safety Range Worst Case Scenario Pt CSt Pi CSi X= CSr/SFr SIR= Pt/Pi(X-1)θ

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Carrier Sense Range Control Channel Adaptive CS

Carrier Sense Range Safety Range Transmission Power Control Pt CSt Pi - Pε CSi SIR

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Carrier Sense Range Control Channel Adaptive CS

Carrier Sense Range Safety Range Carrier Sense Threshold Control Pt CSt Pi CSi - CSε SIR

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Carrier Sense Range Control Channel Adaptive CS

Carrier Sense vs. Transmission Power

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Carrier Sense Range Control Channel Adaptive CS

Carrier Sense Range Safety Range Why Not Use the Minimum Carrier Sense Threshold?

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Safety V2V Carrier Sense Range Control Channel Adaptive CS

Carrier Sense Range = Competition for Channel Access Safety Range Why Not Use the Minimum Carrier Sense Threshold?

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Vehicular Density

 More neighbours – longer back-off  More neighbours – more expired beacons  More neighbours – more collisions

Control Channel Safety V2V

Collision Capture Effect Capture Effect

Carrier Sense Range Adaptive CS Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Vehicular Density

 More neighbours – longer back-off  More neighbours – more expired beacons  More neighbours – more collisions

Control Channel Safety V2V

Collision

Carrier Sense Range Adaptive CS Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Adaptive Carrier Sense Threshold

 Low CSt value under low density  High CSt value under high density  Beacon-based density estimation – λ  CSt= f(λ)

Adaptive CS Control Channel Safety V2V Carrier Sense Range Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Simulation Study

 JiST/SWANS framework  Street Random Waypoint mobility model  Three different real maps from TIGER database  Medium and high vehicular density

Adaptive CS Control Channel Safety V2V Carrier Sense Range Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Adaptive CS Control Channel Safety V2V Carrier Sense Range

Beaconing Reception Probability for different Densities and CS Thresholds

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Adaptive CS Control Channel Safety V2V Carrier Sense Range

Impact of the Carrier Sense Range

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Adaptive CS Control Channel Safety V2V Carrier Sense Range

Adaptive vs. Best Fixed CSt

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Adaptive CS Control Channel Safety V2V Carrier Sense Range

Different Optimal Values for CSt

Adaptive vs. Best Fixed CSt

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Adaptive CS Control Channel Safety V2V Carrier Sense Range

Vehicular Density Adaptive Mechanism CSt= -95 dBm CSt= -85 dBm CSt= -75 dBm 25 veh/lane/km 91.02% 86.42% 89.88% 88.64% 35 veh/lane/km 86.12% 78.38% 84.27% 81.81% 45 veh/lane/km 81.41% 69.76% 76.32% 80.20%

Adaptive vs. Best Fixed CSt

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Adaptive CS Control Channel Safety V2V Carrier Sense Range

Distribution of CSt for the Adaptive Mechanism

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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Conclusion

 The properties of the CCH need to be taken into account when studying V2V communication  The carrier sense mechanism represents the basis for CSMA/CA channel access techniques and should receive more attention  Carrier sense threshold control is more powerful than transmission power control on the VANET CCH  A simple adaptive mechanism can bring important performance improvement in IEEE 802.11p networks

Adaptive Carrier Sense Mechanism in Safety VANETs Razvan Stanica University of Toulouse IVN 2011

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University of Toulouse Institut de Recherche en Informatique de Toulouse

Razvan Stanica, Emmanuel Chaput, André-Luc Beylot

Adaptive Carrier Sense Mechanism in Safety Vehicular Ad-hoc Networks

IVN Exploratory Seminar INRIA Rocquencourt - 15 December 2011