1. doc.: IEEE 802.11-09/0832r1 Submission Woong Cho, ETRI July 2009 Slide 1 Enhancement Technology for Vehicular Communications Date: 2009-07-15 Authors:

2. doc.: IEEE 802.11-09/0832r1 Submission Woong Cho, ETRI July 2009 Vehicular Communications 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 Slide 2

3. doc.: IEEE 802.11-09/0832r1 Submission Woong Cho, ETRI Vehicular Communications Standard 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 July 2009 Slide 3

4. doc.: IEEE 802.11-09/0832r1 Submission Woong Cho, ETRI Some Drawbacks of 802.11p 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 July 2009 Slide 4

5. doc.: IEEE 802.11-09/0832r1 Submission Woong Cho, ETRI Enhancement Technology in PHY 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 July 2009 Slide 5

6. doc.: IEEE 802.11-09/0832r1 Submission Woong Cho, ETRI July 2009 Slide 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. doc.: IEEE 802.11-09/0832r1 Submission Woong Cho, ETRI Handover Issues 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 July 2009 Slide 7

8. doc.: IEEE 802.11-09/0832r1 Submission Woong Cho, ETRI Next Step in Vehicular Communications 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 July 2009 Slide 8

9. doc.: IEEE 802.11-09/0832r1 Submission Woong Cho, ETRI Straw Poll Yes : No : Don’t care : Need more information : July 2009 Slide 9 Q. Should IEEE 802.11 WNG receive further presentations on the topic of enhancement technology for vehicular communications?