DOI QR코드

DOI QR Code

Random Backoff Scheme of Emergency Warning Message for Vehicle-to-Vehicle Communications

차량 간 통신에서 충돌을 완화하기 위한 랜덤 백오프 방안

  • 변재욱 (울산대학교 전기공학부) ;
  • 권성오 (울산대학교 전기공학부)
  • Received : 2011.12.31
  • Accepted : 2012.03.16
  • Published : 2012.03.30

Abstract

In this paper, we propose a random backoff scheme for Emergency Warning Messages (EWMs) in the vehicle-to-vehicle environment. The EWMs are disseminated from a vehicle that detects an emergency situation to other vehicles in a multi-hop fashion. Since the vehicle-to-vehicle communication based on IEEE 802.11 adapts CSMA/CA, the density of vehicles increase the probability of collisions between transmissions. Moreover, in the presence of background traffic, the EWM should have a higher priority than that of other messages in neighboring vehicles. To that end, we propose the Distant-Dependent Adaptive Backoff (DDAB) scheme, which set a different contention window for random backoff depending on the distance from the sender to the receiver. In the case when a vehicle is expected to located in the outskirts of the communication boundary, the proposed scheme makes the contention window size small in order to compete the background traffic transmission. Otherwise the contention window is set to a large number to reduce the collision possibility among the EWM transmissions. Via simulations, we show that the proposed scheme performs better than the previous schemes for EWM.

본 연구에서는 IEEE 802.11을 기반으로 하는 무선 차량 네트워크에서 위험 경고메시지를 효과적으로 전송하기 위한 Backoff 방안을 제안한다. 차량 간 통신인 IEEE 802.11은 위험 경고메시지를 보낼 때 다중 홉 방식을 사용하고, 다중접속방안으로 CSMA/CA를 적용하므로 차량이 밀집될수록 메시지 전송 충돌 확률이 증가한다. 따라서 위험 경고메시지 전송이 시간 지연될 가능성이 높다. 또한, 배경 트래픽이 있을 경우, 위험 경고메시지가 우선 전송이 되어야 한다. 이 같은 문제를 해결하기 위해 위험 경고메시지 전송차량과 수신차량의 위치에 따라 다른 난수발생범위를 갖는 거리 기반 백오프 방안 (DDAB: Distance-Dependent Adaptive Backoff)을 제안한다. DDAB는 배경 트래픽과 경쟁하는 영역의 차량들은 작은 난수발생범위로 설정하여 배경 트래픽보다 전송 우선순위를 높이고, 같은 위험 경고메시지 간 경쟁이 빈번한 영역의 차량들은 큰 난수발생범위를 갖도록 하여 위험 경고메시지간의 충돌을 줄인다. 실험을 통해 기존의 Backoff 방안과 비교하였으며, DDAB 방안을 적용한 경우 기존의 방안을 적용했을 때보다 성능 향상됨을 보였다.

Keywords

References

  1. A. D. Joseph, "Intelligent Transportation Systems," IEEE CS and IEEE ComSoc, June, 2006.
  2. C. D. Wang, J. P. Thompson, "Apparatus and method for motion detection and tracking of objects in a region for collision avoidance utilizing a real-time adaptive probabilistic neural network", US.Patent No. 5,613,039, 1997.
  3. M. Green, "How Long Does It Take To Stop? Methodological Analysis of Driver Perception-Brake Times", Transportation Human Factors, 2(3):195-216, 2000. https://doi.org/10.1207/STHF0203_1
  4. ASTM E2213-03, "Standard Specification for Telecommunications and Information Exchange Between Roadside and Vehicle Systems - 5 GHz Band Dedicated Short Range Communications (DSRC) Medium Access Control (MAC) and Physical Layer (PHY) Specifications," ASTM International, July, 2003.
  5. TechnoCom, "The WAVE Communications Stack: IEEE 802.11p, 1609.4 and 1609.3", IEEE VTC'07, September, 2007.
  6. K. Bilstrup, E. Uhlemann, E. G. Strom, U. Bilstrup, "Evaluation of the IEEE 802.11 MAC method for Vehicle-to-Vehicle Communication," IEEE magazine, 2008.
  7. P. Brenner, "A Technical Tutorial on the IEEE 802.11 Protocol," Breezecom Wireless Communication, 1997.
  8. B. Kwak, N. Song, L. E. Miller, "Performance Analysis of Exponential Backoff," IEEE/ACM Transactions on Networking, VOL. 13, NO. 2, pp, 343-355, April, 2005. https://doi.org/10.1109/TNET.2005.845533
  9. F. Ye, M. Adams, S. Roy, "V2V Wireless Communication Protocol for Rear-End Collision Avoidance on Highways," ICC 2008, pp,375-379, 2008.
  10. S. Biswas, R. Tatchikou, F. Dion, "Vehicle-to-Vehicle Wireless Communication Protocols for Enhancing Highway Traffic Safety," IEEE Communications Magazine, pp74-82, January, 2006.
  11. 강문수, "V2I, V2V 차량 통신을 위한 MAC 기술," Information Network Review, Vol. 22, May, 2008.
  12. C. Han, M, Dianati, R. Tafazolli, R. Kernchen, "Throughput Analysis of the IEEE 802.11 Enhanced Distributed Channel Access Function in Vehicular Environment," 2010.
  13. B. A. Forouzan, Data Communications and Networking, McGrawHill, 4th Ed., 2006.
  14. 이승관, "A study of Dynamic Channel MAC mechanism in WAVE," MS dissertation, Hanyang University, 2010