WIRELESS COMMUNICATIONS FOR TRAFFIC CONTROL SYSTEMS

Wireless communication systems are playing an important role in the implementation of closed-loop and system wide traffic signal controls. As licensed frequencies are becoming scarce the emergence of radio communications systems utilizing the unlicensed band or spread spectrum allocations are increasingly being considered for new and retrofit applications. In the past, customers needing wireless communication systems would be required to obtain an FCC license. In some localities, licenses are becoming difficult, or even impossible to obtain. A popular solution to the licensing problem is provided by the emergence of Spread Spectrum (SS) technology. This new digital technology provides most of the capabilities and performance of a licensed radio system with a license-free approach. For long distance data communications in a control or data gathering application frequency hopping spread spectrum radios provides a robust solution. Spread Spectrum typically uses the frequency band of 902 to 928 MHz. Today's new digital radios employ frequency hopping within this range to ensure maximum performance and maximum reliability for SCADA communications. Sophisticated hopping sequences and forward error correction reduces interference from unwanted sources. These radio enhancements provide very low bit-error rates and greater range of use. Many if not all the traffic control manufacturers are currently offering wireless communications solutions to the traffic control community, yet there is a large gap in the understanding of the application of such technology for closed loop and system wide implementation, this paper should help to close the gap between engineer and end-user. This paper briefly discusses the historical background of spread spectrum radio, FCC rules and regulations, and the definition and application of direct sequence and frequency hopping techniques. Also covered are system architecture options design, and installation considerations

Language

  • English

Media Info

  • Pagination: 13 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00776989
  • Record Type: Publication
  • Source Agency: UC Berkeley Transportation Library
  • Files: PATH
  • Created Date: Nov 17 1999 12:00AM