Thursday 10 April 2014

CALM, DSRC (Dedicated short-range communications) Standards-short Info

CALM: CALM stands for Communication Access for Land Mobile

CALM enables the following communication modes:

  • Vehicle-to-Infrastructure (V2I)
  • Vehicle-to-Vehicle (V2V)
  • Infrastructure-to-Infrastructure (I2I)

Methods of transmission used by CALM can be any one of these :      

·         Infrared

·         GSM

·         DSRC 5.8-5.9 GHz (legacy systems)

·         IEEE 802.11 standard

·         Bluetooth

·         RFID

DSRC:  Dedicated short-range communications

DSRC :One-way or two-way short-range to medium-range wireless communication channels specifically designed for automotive use, it consists of a collection of standards for all OSI layers and still some are in review phase

    EN 12253:2004 :Physical layer using microwave at 5.8 GHz
    EN 12795:2002 :DSRC Data link layer: Medium Access and Logical Link Control
    EN 12834:2002 :Application layer
    EN 13372:2004 :DSRC profiles for RTTT applications
    EN ISO 14906:2004:Application interface

In October 1999: FCC: allocated 75 MHz of spectrum in the 5.9 GHz band to be used by intelligent transportation systems (ITS).
In August 2008: ETSI allocated 30 MHz of spectrum in the 5.9 GHz band for ITS.

V2I (Vehicle-to-Infrastructure)

·         Two intersection RSE messages enable a suite of intersection-related safety applications.

·         SPaT message - Signal Phase and Timing

·         MAP message – Intersection geometry

·         Other RSEs can send Traveler Information message on curve speed, height restriction, icy roads, etc.

·         IP data exchange with servers in the Internet – RSE acts as forwarder


·         Each vehicle broadcasts its core state information in a “Basic Safety Message” (BSM) nominally 10 times/sec.

·         BSM is sent in 360o pattern using IEEE 802.11p technology.

·         Upon receipt of BSM, vehicle safety host builds model of each neighbor’s trajectory, assesses threat to host vehicle, warns driver (or takes control) if threat becomes acute.


DSRC ppt from