1. Vehicular Ad-hoc Network Survey
Kyoungbok Kim

2. 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

3. 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

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

5. 1. Overview of VANET IEEE 802.11p
Use CSMA/CA (+EDCA)
Periodic information sending: 100ms
Coverage 1000m (Wi-Fi < 100m)
Comparison of IEEE a(Wi-Fi) and IEEE p
고속이동을 위해 대역폭을 줄이고 인증절차를 없앴다
IEEE a
IEEE p
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

6. 2. Trends and Issues Congestion control
- contention in the CCH in p 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

7. 2. Bandwidth allocation issue

8. 2. Congestion control research

9. 2. Congestion control research

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

11. 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

12. 3. Frequency band for ITS

13. 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 Multichannel Operation)

14. 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

15. 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

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

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

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

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

20. 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

21. 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 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

22. References
[1] “Distributed Congestion Control Approaches for the IEEE p 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 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 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

23. Thank you !