**Document IWG-2/010**

**Author: D. Weinreich**

**17 April 2001**

**WRC-2003 ADVISORY COMMITTEE**

**DRAFT PRELIMINARY VIEWS ON WRC-03**

**WRC-2003 Agenda Item: 1.6** - to consider regulatory measures to
protect feeder links (Earth-to-space) for the mobile satellite service
which operate in the band 5150-5250 MHz, taking into account the latest
ITU-R Recommendations (for example, Recommendations ITU-R S.1426, ITU-R
S.1427 and ITU- R M.1454);

**ISSUE:** Regulatory measures for the protection of non-GSO MSS Feeder
Uplinks at 5150-5250 MHz potentially including power flux density limits
at the spacecraft altitude, limits on the output powers and constraints
on the deployment of Fixed and Mobile Service transmitters in this band.

**BACKGROUND:** The proliferation of transmitters in the Fixed and
Mobile Services providing applications such as Radio Local Area Networks
(RLANs) and other non-licensed applications presents the threat of
potentially serious interference to the feeder uplinks of non-GSO Mobile
Satellite Service systems, operating in the Fixed Satellite Service.
Regulatory measures must be devised that can effectively protect these
vital links from unacceptable interference.

The band 5150-5250 MHz is allocated on a primary basis to the FSS and
its use is limited to non-GSO MSS feeder links by footnote S5.447A. This
band is also allocated by footnote S5.447 to the mobile service (MS) on
a co-primary basis in 27 countries in Regions 1 and 3 subject to S9.21.
Administrations are currently considering the introduction of Fixed and
Mobile Services in the band 5150-5250 MHz on a national and unlicensed,
uncoordinated basis (see Recommendation ITU-R M.1454).

At WRC-2000, Resolution 1156 called for studies by the ITU-R leading to
technical and operational recommendations to facilitate sharing between
existing services and Fixed and Mobile Services, including RLANs in the
bands 5150-5350 MHz and 5470-5725 MHz. It is anticipated that these
studies will provide assurance that allocation to Fixed and Mobile
Services, in these bands, can co-exist with incumbent non-GSO MSS feeder
links and Aeronautical Radionavigation Service systems.

During the 1998-2000 study period, considerable time and effort was
spent on the development of three ITU-R Recommendations addressing this
topic.

JRG 8A-9B developed Recommendation ITU-R M.1454 entitled \"EIRP Density
Limit and Operational Restrictions for RLANs or Other Wireless Access
Transmitters in order to Ensure the Protection of Feeder Links of
Non-Geostationary Systems in the Mobile Satellite Service in the
Frequency Band 5150-5250 MHz.\" This Recommendation calls for
implementers of wireless access systems to limit the EIRP density of
such transmitters to 10mW in any 1 MHz, operate these transmitters only
indoors and ensure that the aggregate emissions of these transmitters do
not exceed the power flux density limit given in Recommendation ITU-R
S.1426.

Working Party 4A also considered the protection of MSS Feeder Links from
wireless access system emissions and created two Recommendations in
response to these studies. Recommendation ITU-R S.1426, entitled
\"Aggregate Power Flux Density Limits at the FSS Satellite Orbit for
Radio Local Area Network (RLAN) Transmitters Operating in the 5150-5250
MHz Band Sharing Frequencies with the FSS (RR No. S5.447A)\" imposes an
aggregate power flux density limit on Fixed and Mobile Services equal to
--124 --20log~10~(h~sat~/1414) dB(W/MHz/square meter), where h~sat~ is
the altitude of the spacecraft in kilometers. This limit is for the
protection of FSS satellites using full earth coverage receive antenna
beams.

Further, WP 4A created Recommendation ITU-R S.1427, entitled
\"Methodology and Criterion to Assess Interference from Radio Local Area
Network (RLAN) Transmitters to Non-GSO MSS Feeder Links in the Band
5150-5250 MHz.\" This Recommendation specified that interference from
RLAN transmitters should be assessed on the basis of an increase in
T~sat~, the satellite receiver noise temperature, and, to ensure
protection, this increase should be no greater than 3%. A Note to the
Recommendation indicated that the interference absorbed by the satellite
system should not lead to a reduction in capacity of more than 1%.

Unconstrained deployment of Fixed and Mobile Service applications will
cause unacceptable levels of interference into the feeder uplinks of the
non-GSO MSS. Appreciating this fact, WRC-2000 developed agenda item 1.6
for WRC-2003, which calls for the consideration of regulatory measures
to protect the FSS (Earth-to-space) allocation in the band 5150-5250 MHz
from RLAN interference.

**PRELIMINARY VIEW:** The establishment of regulatory measures to
protect non-GSO MSS feeder uplinks from unlicensed applications in the
Fixed and Mobile Service allocations is necessary to protect these
feeder links from unacceptable interference. These regulatory measures
could include Radio Regulations which address the emission and
deployment limitations and the power flux density limit at the non-GSO
MSS satellite altitude for transmitters in the Fixed and Mobile
Services. (17 April 2001)