Radio CBTC For The Las Vegas Monorail
Free (open access)
C. Bantin & J. Siu
In July 2004, the Las Vegas Monorail entered revenue service with a revolutionary new radio communication-based train control system (CBTC). The radio system is the world’s first application of wireless technology in a revenue-earning urban rail transit system using antennas and over-the-air transmission. The system has performed perfectly and is a testament to the application of sophisticated technology to a challenging environment. The entire data communications system (DCS) serving the CBTC is based on the Ethernet 802.3 open-standard. The radio segment uses the 802.11 extension of this standard to mobile networks. Specifically the 802.11 frequency hopping spread spectrum (FHSS) variant is used because it has the best resistance to interference while providing more than adequate data rates. The entire network was designed and built using commercial off-the-shelf equipment, where the 802.11 standard has been implemented for mobile networks capable of routine hand-overs between access points at up to 100 km/h. The system design, using the standard in the 2.4 GHz ISM band, involved several detailed stages to ensure faultless operation. First the nature of the CBTC data has to be understood and the network has to be designed to accommodate this data. Next the link budgets have to be determined as applied to the unique guideway environment used by the monorail. Signal strength surveys were carried out to determine where to place access points such that there was full and redundant coverage throughout the guideway. Furthermore severe co-user interference (802.11b or WiFi) is present at several locations along the guideway and had to be accommodated. Finally the operating parameters of the radios had to be fully understood to optimize the hand-over process. The complete system was extensively tested and many weeks of data was collected in order to verify that the radio system met the performance requirements. Keywords: radio CBTC, ATC, driverless, monorail.
radio CBTC, ATC, driverless, monorail.