V2X Flashcards
SPaT
Signal, Phase, and Timing
Information about traffic signals: What phase an intersection is on, and how much time remains.
MAP
A MAP message defines the intersection geography (literally a map), and is used in conjunction with a SPaT message to understand the state of the intersection
BSM
Basic Safety Message
A message sent out usually at a 10Hz rate (10x a second) by a vehicle’s OBU on its given position and status.
RSU
Roadside Unit
Broadcasts and receives V2X radio messages at an intersection, and communicates with the traffic controller and other services via Ethernet
OBU
Onboard Unit
V2X device on a vehicle that communicates with RSUs and other OBUs. Typically sends BSMs, and listens for SPaT+MAP (and other BSMs).
DSRC
Dedicated Short Range Communication
Wireless standard for sending V2X messages over radio. Has been largely replaced with CV2X although we still offer DSRC at Mcity.
CV2X
Wireless standard for sending V2X messages over radio. This replaced DSRC and utilizes cellular technology
J2735
SAE standard message set for V2X. This contains the definitions for “SPaT”, “MAP”, etc. (used by both DSRC and CV2X)
IFM / IMF
Immediate Forward Message / Immediate Message Forward (interchangeable)
The function on an RSU to broadcast messages received via Ethernet across its radio link (usually the receiving port is UDP 1516)
SRM
The function on an RSU to periodically broadcast messages that are stored locally on the device, such as MAP messages once per second. (As opposed to IMF)