Vehicular Ad-hoc Network Survey 2014.07.02 Kyoungbok Kim

Overview of VANET 01 02 Trends and Issues 03 ETSI ITS G5(EU) vs IEEE WAVE(USA) A Performance Study of Cooperative Awareness in ETSI ITS G5 and IEEE WAVE 04

1. Overview of VANET 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 편의성: 교통 흐름정보 실시간으로 안정성: 차량간 안정성 확보로 사고를 줄일 수 있다. 실제로 미국에서 2012년

1. A example of V2V 편의성: 교통 흐름정보 실시간으로 안정성: 차량간 안정성 확보로 사고를 줄일 수 있다. 실제로 미국에서 2012년.. 3000대 80%예방 2017년까지 의무화 추진

1. Overview of VANET 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 고속이동을 위해 대역폭을 줄이고 인증절차를 없앴다 IEEE 802.11a IEEE 802.11p Default Bandwidth 20 MHz 10 MHz Data rates 6, 9, 12, 18, 24, 36, 48, 56 3, 4.5, 6, 9, 12, 18, 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

2. Trends and Issues 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

2. Bandwidth allocation issue

2. Congestion control research

2. Congestion control research

3. ITS G5(EU) vs IEEE WAVE(USA) Comparison of the protocol stacks

3. Frequency band for ITS 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

3. Frequency band for ITS

3. Frequency band for ITS 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) G5 채널 할당 – Data rate, Power 다 다르다. ETSI ITS-G5 Channel Allocation WAVE Channel Allocation(IEEE 1609.4 Multichannel Operation)

3. Congestion control in WAVE No RTS/CTS -> ACK이 존재하고 Contention Window를 조정하기 어렵기 때문에 Time Slot 낭비가 일어나고 Congestion이 더욱 발생 Adaptive Offset Slot

3. Congestion control in ETSI ITS G5 ETSI Distributed Congestion Control (DCC) algorithm to cooperatively adapt their behavior in transmitting safety messages No RTS/CTS -> ACK이 존재하고 Contention Window를 조정하기 어렵기 때문에 Time Slot 낭비가 일어나고 Congestion이 더욱 발생 Adaptive Offset Slot DCC state machine with four control parameters

3. Less is more No RTS/CTS -> ACK이 존재하고 Contention Window를 조정하기 어렵기 때문에 Time Slot 낭비가 일어나고 Congestion이 더욱 발생 Adaptive Offset Slot

3. Less is more No RTS/CTS -> ACK이 존재하고 Contention Window를 조정하기 어렵기 때문에 Time Slot 낭비가 일어나고 Congestion이 더욱 발생 Adaptive Offset Slot

4. A Performance Study of Cooperative Awareness in ETSI ITS G5 and IEEE WAVE Cooperative Awareness Message

4. A Performance Study of Cooperative Awareness in ETSI ITS G5 and IEEE WAVE Moving traffic = 170 vehicles/km, 100% penetration rate Empirical Distribution

4. A Performance Study of Cooperative Awareness in ETSI ITS G5 and IEEE WAVE Figure 6a, 50%: WAVE’s performance is lower than ITS-G5

4. A Performance Study of Cooperative Awareness in ETSI ITS G5 and IEEE WAVE 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 Figure 6a, 50%: WAVE’s performance is lower than ITS-G5

References [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

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