26
U.S. Department of Transportation
Research and Innovative Technology Administration
Active Safety Latency Requirements (secs)
Traffic Signal Violation warning
0.1
Curve Speed Warning
1
Emergency Electronic Brake Lights
0.1
Pre-Crash Sensing
0.02
Cooperative Forward Collision Warning
0.1
Left Turn Assistant
0.1
Lane Change Warning
0.1
Stop Sign Movement Assistance
0.1
Note:  Y-axis not to scale for illustration purposes
Data source:  Vehicle Safety Communications Project – Final Report
Latency (in seconds)
Most Stringent latency
requirement for Active Safety
(.02 sec)
Least stringent latency
requirement for Active Safety
( 1 sec)
Communications Technologies
.02
5.0
1.0
2.0
3.0
10
20
40
60
4.0
WiFi 802.11
(3 – 5 secs)
Terrestrial Digital Radio &
Satellite Digital Audio Radio
(10 – 20 secs)
WiMax
(1.5 – 3.5 secs)
Bluetooth
(3 – 4 secs)
Two-Way Satellite
(60+ secs)
5.9 GHz DSRC (.0002 secs)
Cellular
(1.5 – 3.5 secs)
.01
Latency vs. Communications Technologies For IntelliDriveSM