Electrical Engineering
      and Computer Sciences

Electrical Engineering and Computer Sciences


UC Berkeley


2009 Research Summary

Multiband Wireless Vehicular Communications (DSRC)

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Ian Tan, Youwei Zhang, Carl Chun, Ken Laberteaux1 and Ahmad Bahai

Toyota Motors Inc.

Over the past two decades, electronics have played an increasingly essential role in controlling automobiles. However, what has been noticeably absent is a means for vehicles to communicate in a reliable and timely manner. Such vehicle-area-networks (VANETs) hold the potential to increase roadway safety, provide transportation-related services, and aid in large-scale traffic management.

To enable such communications, the Federal Communications Commission (FCC) has allocated a frequency band at 5.9 GHz for dedicated short-range communications (DSRC) in vehicular environments. Our research seeks to enable robust automotive communications by measuring and quantifying impairments present in the vehicular wireless channel, developing relevant improvements, and analyzing the impact of physical layer behavior upon other areas of the DSRC architecture.

To investigate DSRC-band impairments, we developed a vehicle-to-vehicle, GPS-enabled channel sounding platform and utilized it in an extensive field measurement campaign spanning various speeds and line-of-sight conditions. Based on data collected at over 200 locations, we have presented a comprehensive characterization of the vehicular wireless channel [1]. From these measurements, which suggested a potential problem with shortened coherence times, we proposed a time-domain differential OFDM modification to the current DSRC standard [2]. In the near future, we will be conducting more detailed measurements to quantify angle-of-arrival properties at 5.9 GHz, as well as a second measurement campaign at 700 MHz. Subsequent results will drive further investigation into multi-antenna beamforming and alternative vehicular communication methods. Furthermore, deployment scenarios for DSRC and our measurements have prompted our continuing research into power control, interference mitigation, and multi-channel MAC protocols for DSRC.

I. Tan, W. Tang, K. Laberteaux, and A. Bahai, "Measurement and Analysis of Wireless Channel Impairments in DSRC Vehicular Communications," IEEE International Conference on Communications, May 2008, pp. 4882-4888.
Y. Zhang, I. Tan, C. Chun, K. Laberteaux, and A. Bahai, "A Differential OFDM Approach to Coherence Time Mitigation in DSRC," Proceedings of the Fifth ACM international Workshop on Vehicular Inter-Networking, San Francisco, CA, September 2008. DOI=http://doi.acm.org/10.1145/1410043.1410045.

1Toyota Research