Transcript Slides
2014.07.02 Kyoungbok Kim 01 Overview of VANET 02 Trends and Issues 03 ETSI ITS G5(EU) vs IEEE WAVE(USA) 04 A Performance Study of Cooperative Awareness in ETSI ITS G5 and IEEE WAVE ITS(Intelligent Transport System) : ICT + Transportation system V2X : Vehicular communication technology for safety and ease - V2V - V2I VANET : Vehicular networks can be connected autonomously, rapidly 2 / 17 3 / 17 IEEE 802.11p - Use CSMA/CA (+EDCA) - Periodic information sending: 100ms - Coverage 1000m (Wi-Fi < 100m) Comparison of IEEE 802.11a(Wi-Fi) and IEEE 802.11p IEEE 802.11a IEEE 802.11p Default Bandwidth 20 MHz 10 MHz Data rates 6, 9, 12, 18, 24, 36, 3, 4.5, 6, 9, 12, 18, 48, 56 24, 27 Frequency Band 5 GHz ISM 5.9 GHz dedicated Authentication O X Symbol duration 4 us 8 us Guard period 0.8 us 1.6 us 4 / 17 Congestion control - contention in the CCH in 802.11p technology can be easily achieved, DCC (Decentralized Congestion Control) mechanism proposed by ETSI is a complex architecture QoS policy at level 3(IP level) - applied to control the bandwidth occupation and enable congestion avoidance Security issues - protection against malicious manipulations and masquerade of message information (ex road safety messages) Privacy issues - respect of private information owned and transmitted by the vehicle (ex vehicle tracking) Bandwidth allocation in Korea 5 / 17 6 / 17 7 / 17 8 / 17 Comparison of the protocol stacks 9 / 17 North America – 5.850‐5.925 GHz Intelligent Transportation Systems • 75 MHz – 7x10 MHz channels • 1 control channel and 6 service channels EU – 5.875‐5.925 GHz (30 MHz + 20 MHz) • Road traffic safety – 1x10 MHz control channel and 2x10 MHz service channels • Traffic efficiency – 2x10 MHz service channels 10 / 17 11 / 17 A ITS-G5 station must be able to decode packets on two separate channel at the same time(2 receiver) A WAVE station can use the time division to switch back and forth between CCH and SCH(1 receiver) ETSI ITS-G5 Channel Allocation WAVE Channel Allocation(IEEE 1609.4 Multichannel Operation) 12 / 17 / 17 ETSI Distributed Congestion Control (DCC) algorithm to cooperatively adapt their behavior in transmitting safety messages DCC state machine with four control parameters / 17 / 17 / 17 17 / 17 18 / 17 19 / 17 One of the main differences in ITS G5 is that there is no alternating access scheme IEEE 1609.4 causes problems by reducing the available bandwidth by more than a half and by introducing synchronization effect at interval border DCC mechanism improves the overall system performance to some extent, but introduces new effect such as the local and global oscillation of state machine ETSI ITS G5 performs better than WAVE at higher penetration rates but has problems even at low distances 20 / 17 [1] “Distributed Congestion Control Approaches for the IEEE 802.11p Vehicular Networks”, IEEE Intelligent transportation systems magazine, Oct 2013 [2] “IT 융합 기반 V2X 차량 통신 기술개발 동향”, Journal of Communications & Radio Spectrum, Oct 2012 [3] “Standardization of Wireless Vehicular Communications within IEEE and ETSI“, IEEE VTS Workshop on Wireless Vehicular Communications, Nov 2011 [4] “ITS European profile standard for the physical and medium access control layer of Intelligent Transport Systems operating in the 5 GHz frequency band”, ETSI ES 202 663 V1.1.0, Jan 2010 [5] ”ITS Decentralized Congestion Control Mechanisms for Intelligent Transport Systems operating in the 5 GHz range Access layer part”, ETSI ES 102 687 V1.1.1, July 2011 [6] “On Medium Access and Physical Layer Standards for Cooperative Intelligent Transport Systems in Europe”, Proceedings of the IEEE, 2011 [7] “A Performance Study of Cooperative Awareness in ETSI ITS G5 and IEEE WAVE”, 10th Annual Conference on Wireless On-Demand Network Systems and Service, 2013 21 / 17 22 / 17