JPL's Wireless Communication Reference Website Chapter: Network Concepts and Standards Section: DSRC

Dedicated Short-Range Communications (DSRC) communication architecture

The standardization of application services and the corresponding communication architecture of vehicle-roadside communications (DSRC-Dedicated Short-Range Communications) was pursued in CEN TC 278 (Europe) and ISO TC 204 (International) and first draft standards have been issued during 1995. From 1996 to 1998 the validation of the DSRC standards was pursued in the European research project VASCO (Validation of Dedicated Short- Range Communications).

 
Figure 4:   DSRC architecture

The DSRC communication architecture has been developed by CEN TC 278 WG 9 (see figure 4) according to the ISO-OSI philosophy. Due to the limited system functionality and the real-time constraints a three layer approach has been chosen.

• The DSRC Physical Layer standard proposals provide specifications for two media:
  • Micr wave at 5.8 GHz, in particular the bands 5.795-5.805 GHz according to CEPT recommendation for pan-European usage, and 5.805-5.815 GHz available for national usage (see 6)

  • Infrared at 850 nm (see 7)

  The default downlink / uplink data rates are 500 kbit/s and 250 kbit/s, respectively. Lower and higher data rates can be chosen after a negotiation phase between OBE and RSE.

• The DSRC Data Link Layer consists of the Logical Link Control (LLC) and Medium Access Control (MAC) sub-layers. The LLC sub-layer has been adapted from the IEEE 8088.2 specifications for connection-less and connection-oriented services. The MAC sub-layer caters for efficient contention mechanisms to avoid and resolve data collisions in multi-lane environments 5. The DSRC Data Link Layer has been designed in a medium-independent way, i.e. the parameters can be adapted to both media available for the DSRC.

• The DSRC Application Layer provides a service interface for the applications and specifies fragmentation, application multiplexing (see 7) and a common initialisation mechanism for each communication process between OBE and the roadside equipment (RSE).

On top of this architecture, application standards are being developed by the application-oriented working groups within CEN TC 278, e.g. for Automatic Fee Collection (AFC) (to be issued end of 1996) and Traveller and Traffic Information (TTI) (to be issued in 1996).

JPL's Wireless Communication Reference Website © Christian Wietfeld (author) and Jean-Paul M.G. Linnartz (Ed.), 1996.