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Enhancement Technology for Vehicular Communications

Explore V2V and V2I applications, WAVE technology, MAC layer enhancements, and handover issues for improved vehicular communication.

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Enhancement Technology for Vehicular Communications

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  1. Enhancement Technology for Vehicular Communications Date: 2009-07-15 Authors: Slide 1

  2. V2V(Vehicle-to-Vehicle) applications: • Vehicle safety via vehicle multi-hop communications • V2I(Vehicle-to-Infrastructure) applications: • ITS/Telematics via bi-directional communications • Basic requirements • Communication schemes: broadcasting, unicasting • Mobility: up to 200km/h • Long packet transmission:~2K bytes • Packet Latency: 100 msec < • Networking: V2I, V2V Vehicular Communications

  3. WAVE(Wireless Access in Vehicular Environments) • PHY/MAC: 802.11p • Upper layers: 1609.x • 802.11p • PHY layer(10MHz Bandwidth) • Uses scaled version of 802.11a-20MHz • Defines sharp spectrum mask in transmission • Defines enhanced channel rejection at the receiver • MAC layer • Uses CSMA/CA of 802.11 • Uses AIFS(Arbitration InterFrame Space) in 802.11e for QoS supplement Vehicular Communications Standard

  4. PHY layer • Channel estimation • Adopts 802.11 scheme, i.e., preamble based estimation, without any modification  Suitable for short packet transmission  Not sufficient for long packet transmission • MAC layer • Collision • Most safety applications use broadcasting  As the # of nodes increases, probability of collision increases • Fairness • Unbalanced bandwidth requirements in V2I  CSMA/CA cannot provide differentiated channel access priority between RSEs and OBUs Some Drawbacks of 802.11p

  5. Need to guarantee long packet transmission • Modification of channel estimation • Ex) Midamble based channel estimation • 11-08-0875r1 “Radio Transmission Technology for V2V/V2I Applications” • 11-08-1046r0 “Channel Modeling and the Midamble Insertion Effects”  Verify the benefit of midamble based system Enhancement Technology in PHY

  6. Provide priority access • Consider TDMA-like system • Ex) Hybrid MAC: TDMA+CSMA/CA • 11-08-0875r1 “Radio Transmission Technology for V2V/V2I Applications” • 11-08-1273r1 “Hybrid MAC for VANET”  Hybrid MAC has better throughput than CSMA/CA Enhancement Technology in MAC

  7. Vehicles are move rapidly along roads • Handover occurs often, and handover issue becomes more important than 802.11 • When OBU enters new RSE, it takes long channel scanning time to carry out handover • 802.11p does not provide a sufficient answer for handover issue • Fast handover scheme in vehicular network is needed to provide continuous communication between RSEs Handover Issues

  8. Consider • Modification of PHY • To support long packet transmission  Enable to provide various services • Modification of MAC • To provide priority access  Solve collision problem and increase throughput • Fast handover • To achieve continuous communication links  Provide communication environments with high quality Next Step in Vehicular Communications

  9. Yes : No : Don’t care : Need more information : Straw Poll Q. Should IEEE 802.11 WNG receive further presentations on the topic of enhancement technology for vehicular communications?

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