A Query on Dedicated Short Range Communications ("DSRC")
(As noted in the CGC Communicator  #632 for May 11, 2004)

DSRC is a short range communications system that has had a number of varied suggested uses proposed for communications to and from vehicles.  For example, the service could be used to exchange payment data between a toll booths and a passing vehicle, thus eliminating the traditional and cumbersome manual process.  After reading a story on the technology, Bob Gonsett posed a question to Richard Doering about the potential use of the service to deliver "hi-fi" material such as music.   Richard has plenty of valuable insight on DSRC and has been following the development of this new technology and its applications for some time.

Bob: "Can DSRC carry hi-fi audio broadcasts to vehicles (music, etc.)?  If so, this would capture the interest of many broadcasters and would-be broadcasters."

Richard:  "DSRC is not a broadcast service, and probably will not become a continuous ribbon coverage area, rather there are hot spots such as at a gas station or rest area, or at a spot along the road where traffic info/safety warnings are needed.  It is primarily a high performance messaging service for short, very timely, safety and traffic information messages, although there are many prospective uses outlined in the NPRM and R & O, and in standards activities.

It (hi-fi material) appears to be allowed under the FCC report and order. This would be under the category of private downloads of music files on a secondary basis to public safety messages, as enforced by the protocol, channelization and licensing attributes on DSRC (5.9 GHz band) frequencies.

I would also note that there have been discussions and demos using dual mode equipment where such downloads also would be in the nearby 5.2 or 5.8 GHz unlicensed band, such as 802.11a or UNII bands.  Thus, a vehicular installation may download various files while refueling or parked in the garage that could provide high-fidelity music or entertainment.

The difference between 802.11a and 5.9 GHz DSRC, to a first approximation in the physical medium, is lower data rate for DSRC (1/2 that of 802.11a) to provide better multipath performance along highways and between buildings of urban canyons, and higher allowed power on DSRC, especially for public safety users.

Between support by some of the vehicle manufacturers, and Federal Highways encouragement of the standardization, this medium for communications appears to have "traction" for deployment along roadways.

Hope this unofficial interpretation is helpful.

Richard Doering, WA6CFM

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