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ARRL General Bulletin ARLB072 (1998)

ARLB072 League says 75 MHz too much for DSRC

QST de W1AW  
ARRL Bulletin 72  ARLB072
From ARRL Headquarters  
Newington CT  September 17, 1998
To all radio amateurs 

ARLB072 League says 75 MHz too much for DSRC

The ARRL says the FCC is proposing too much spectrum at 5.9 GHz for
deployment of Dedicated Short Range Communications (DSRC) systems
for intelligent transportation system (ITS) applications. The
League's comments follow a June 11 Notice of Proposed Rulemaking (ET
Docket No 98-95) in which the FCC proposed setting aside 75
MHz--5.850 to 5.925 GHz for use by ITS on a coprimary basis. The
Amateur Service has a secondary allocation at 5.650 to 5.925 GHz,
sharing with government radars and nongovernment fixed satellite
service uplinks.

The League suggested that if the FCC goes ahead with a 75 MHz
allocation, it should compensate by elevating remaining Amateur and
Amateur Satellite allocations at 5.650 to 5.725 and 5.825 to 5.850
GHz to nongovernment primary ''to insure against future preemption by
nongovernment services with higher allocation status.''

The ARRL said it's not apparent from the FCC's NPRM that 75 MHz of
spectrum is necessary. The DSRC allocation at 5 GHz in Europe is
only 10 MHz wide, the League pointed out, and the FCC Notice does
not account for the disparity ''between that bandwidth and the
claimed need for 75 MHz for unspecified future DSRC applications.''
The League said the Commission ought to explore the opportunities of
frequency reuse and the availability of the 902-928 MHz band for
some DSRC functions.

In earlier comments, the League questioned whether the 5.9 GHz band
was appropriate for DSRC and urged the FCC to look into frequencies
above 40 GHz, where DSRC systems could avoid interference from other

The League also recommended that the Commission mandate prior
coordination between ITS America (a nonprofit ITS promotional
organization) and the League or restrict DSRC facilities to those
using ''listen-before-transmit protocols and frequency-agile
transmitters with roaming channel selection.''

Possible ITS applications include various highway safety systems,
including traffic control, automated roadside safety inspections,
enroute driver information systems, and systems where DSRC-equipped
vehicles could be equipped to more quickly detect traffic congestion
and dispatch emergency personnel or take other actions.

ITS DSRC transmissions would be ''narrowly focused and rapidly
dissipating signals,'' according to ITS America. The FCC has proposed
a maximum of 30 W EIRP for DSRC systems.

A complete copy of the League's comments is on the ARRLWeb at


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