Document IWG-2/006

Author: S. Baruch

April 16, 2001

WRC-2003 ADVISORY COMMITTEE

DRAFT PRELIMINARY VIEWS ON WRC-03

WRC-2003 Agenda Item: 1.15 *--* to review the results of studies
concerning the radionavigation-satellite service in accordance with
Resolutions 604 (WRC-2000), 605 (WRC-2000), and 606 (WRC-2000).

**ISSUES:**

**1. Resolution 604:** To determine whether an aggregate pfd value of
--171 dB (W/m^2^) in a 10 MHz bandwidth at any RA observatory site,
which radionavigation satellite service (RNSS) space-to-Earth systems
operating in the band 5010-5030 MHz cannot exceed for more than 2% of
the time in the band 4990-5000 MHz, adequately protects radioastronomy
in the 4990-5000 MHz band from detrimental interference.

**2. Resolution 605:** (a) To ensure the protection of aeronautical
radionavigation service (ARNS), specifically including Distance
Measuring Equipment (DME), from RNSS space-to-Earth transmissions in the
1164-1215 MHz band; and (b) To assess the need for an aggregate power
flux-density limit on RNSS space-to-Earth transmissions, and if such a
need exists to confirm or revise the provisional aggregate power
flux-density limit adopted in **No. S5.328A** of the Radio Regulations.

**3. Resolution 606:** To ensure, through appropriate technical,
operational, and regulatory studies (including the assessment of the
need for a power flux-density limit on new RNSS (space-to-Earth) systems
in the 1215-1300 MHz band), that the RNSS (space-to-Earth) will not
cause harmful interference to the radionavigation and radiolocation
services.

**BACKGROUND:**

1.  Resolution 604:

WRC-2000 introduced new space-to-space and space-to-Earth allocations to
the RNSS in the band 5010-5030 MHz. For use of the band 5010-5030 MHz by
the RNSS (space-to-Earth), in order to protect MLS systems operating
above 5030 MHz, an aggregate pfd value of --124.5 dB (W/m^2^) in a 150
kHz bandwidth by all space stations of the RNSS service in the band
5030-5150 MHz is specified. To protect radioastronomy from detrimental
interference, a provisional aggregate pfd value of --171 dB (W/m^2^) in
a 10 MHz bandwidth at any RA observatory site cannot be exceeded for
more than 2% of the time in the band 4990-5000 MHz. Under Resolution
**604 (WRC-2000)**, the ITU-R is to review the provisional --171 dB
(W/m^2^/10 MHz) pfd limit.

> 2\. Resolution 605:

WRC-2000 introduced new allocations in the band 1164-1215 MHz for use by
the radionavigation-satellite service ("RNSS") (space-to-space) and
(space-to-Earth) with an aggregate provisional pfd of --115 dB (W/m^2^)
in any 1 MHz produced at the Earth's surface by all space stations
within all RNSS systems and for all angles of arrival. It also stated in
No. S5.328A of the Radio Regulations that the provisions of Resolution
605 (WRC-2000) apply. There was extensive discussion at the WRC with
regards to the need for a pfd limit and the value needed to protect ARNS
(including Distance Measuring Equipment (DME)). Resolution 605 requests
the ITU-R to study the technical, operational, and regulatory aspects of
compatibility between RNSS and ARNS in the band 960-1215 MHz, including
an assessment of the need for an aggregate pfd limit and if such need
exists, to revise, if necessary the provisional pfd limit given in No.
S5.328A concerning the operation of RNSS (space-to-Earth) systems in the
frequency band 1164 -- 1215 MHz.

**3. Resolution 606:**

WRC-2000 introduced allocations to the RNSS (space-to-Earth) in the
1260-1300 MHz band, and for RNSS (space-to-space) in the 1215-1300 MHz
band. Where RNSS use of the 1164-1215 MHz band was made subject to a
provisional aggregate pfd limits, RNSS use of the band 1215-1300 MHz
band is the subject of studies to be conducted pursuant to Resolution
**606 (WRC-2000)**. There are large numbers of GPS receivers operating
in the band 1 215 -- 1 260 MHz. The band 1 240 -- 1 300 MHz is also
allocated on a co*-*primary basis to ARNS and to radiolocation for use
of long range primary radar systems. Among other things, Resolution
**606** calls for studies of "the need for a power flux-density limit
concerning the operation of radionavigation-satellite service
(space-to-Earth) systems in the frequency band 1215 -- 1300 MHz in order
to ensure that the radionavigation-satellite service (space-to-Earth)
will not cause harmful interference to the radionavigation and
radiolocation services."

Also in Resolution **606**, WRC-2000 resolved that no additional
constraints are to be placed on RNSS systems operating in the 1215-1260
MHz band. The Global Positioning System (GPS), an RNSS system which
operates on 1227.6 MHz (24 MHz bandwidth), has been in operation in the
band 1215 -- 1260 MHz since 1988. It provides positioning and navigation
services from space. Currently, this signal is used for high precision
GPS in high productivity applications, such as machine guidance in
survey, construction, agriculture, and mining. With an expanding
capability to receive an additional civilian GPS signal, other civilian
and commercial sectors have yet to be explored. The existing signal will
continue to be a low power signal in the 1215 -- 1300 MHz band. This
signal has been transmitted at its current power level for over 12 years
and has not caused any interference to other users of the band. This has
been accomplished without the need for power flux-density limits in the
Radio Regulations. It is anticipated that in the future there will be
requirements to improve upon the signal.

Studies are currently under way in ITU-R Working Party 8D to address
these three resolutions.

**PRELIMINARY VIEWS:**

**1. Resolution 605:**

The United States of America has a strong need both for RNSS spectrum in
the 1164-1215 MHz band and for the protection of DME systems in the
ARNS. It is participating in ITU-R technical and regulatory studies that
are expected to show how DME systems can be protected while not unduly
constraining the aggregate power flux-density emissions of RNSS systems.
Regardless of the mechanism that is used to provide the requisite
protection to DMEs, it is noted that the ITU-R currently does not have a
methodology that can be used to calculate the power flux-density
produced by RNSS systems, along with appropriate regulatory provisions
that ensure that the desired protection is provided effectively without
unnecessarily delaying or hindering the implementation and provision of
RNSS (space-to-Earth) services.

**2. Resolution 606:**

The United States of America is of the view that there is no need for
any power flux-density limit to be imposed in the 1215-1300 MHz band.
RNSS systems have been successfully operating in the lower portion of
the band (1215-1240 MHz) for more than 12 years with no resultant
interference, and the band is not used by DME systems. Even if ITU-R
studies show that radiolocation and/or ARNS systems require protection
from new RNSS systems in the 1215-1240 MHz band or from RNSS
(space-to-Earth) systems in the 1260-1300 MHz band, it will be necessary
to consider means alternative to power flux-density limits for providing
such protection.

(April 16, 2001)