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| Communications-specifications, Control communications channels, DSRC (dedicated short range, communication)-specifications, ITS-RS (intelligient transportation systems-radio, service), MAC (medium access control), OBUs (on-board (communications) units), OFDM (orthogonal frequency division multiplexing), OSI (open system interconnection), RSU (roadside (telecommunications) unit), Service communications channels, Telecommunications-specifications, Wide-area communications networks, Wireless communications equipment