Document IWG-3/008 (04.11.01)

WRC-2003 ADVISORY COMMITTEE

DRAFT PRELIMINARY VIEWS ON WRC-03

*WRC-2003 Agenda Item 1.29 --* to consider the results of studies
related to Resolutions 136 \[COM5/3\] (WRC‑2000) and 78 \[COM5/23\]
(WRC‑2000) dealing with sharing between non-GSO and GSO systems

**ISSUE (Res. 136)**: Frequency sharing in the range 37.5-50.2 GHz
between GSO and non-GSO FSS networks.

**BACKGROUND (Res. 136)**: Both GSO FSS and non-GSO FSS systems are
planned for operation within the 37.5-42.5 GHz and 47.2-50.2 GHz bands.
FSS systems based on the use of new technologies associated with both
geostationary and non-geostationary orbits are capable of providing the
most isolated regions of the world with high capacity and low-cost means
of communications. WRC-2000 took several steps toward harmonized use of
the band 37.5-42.5 GHz by fixed and space services. The band 37.5-42.5
GHz is now allocated to the FSS (space-to-Earth) on a primary basis in
all three ITU Regions.

WRC-2000 adopted, in Article **S21**, power flux-density (pfd) limits on
GSO and non-GSO FSS space stations in the bands 37.5-40 GHz and
40.5-42.5 GHz in order to protect terrestrial services. The new limits
are provisional, and are subject to review under Resolution 84
\[COM5/28\] (WRC-2000) at WRC-2003. The pfd limits vary between
different band segments, and between geostationary and non-geostationary
systems within each band segment, and will have to be taken into
consideration when addressing sharing between GSO and non-GSO FSS
systems in those band segments.

Sharing studies between GSO FSS networks and non-GSO FSS systems in the
frequency range 37.5-50.2 GHz are underway taking into account the
significant propagation losses at these frequencies, duration of
interference events, differences in planned earth station antenna sizes,
availability requirements, potential mitigation techniques such as
polarization isolation, and the pfd limits in Article **S21**. Sharing
between GSO FSS and non-GSO FSS systems in this range is currently
regulated under No. **S22.2** of the Radio Regulations, which provides
that "\[n\]on-geostationary-satellite systems shall not cause
unacceptable interfer­ence to geostationary‑satellite systems in the
fixed-satellite service and the broadcasting-satellite service operating
in accordance with these Regulations." 

In Resolution 130 (WRC-97), WRC-97 recognized that "the diverging
interpretations arising from No. **S22.2** result in an ambiguous
regulatory status for both existing and future GSO and non-GSO systems
in the FSS in the bands where this provision applies, with consequential
risks for both types of systems." Because there has been little or no
deployment of satellite systems to date in the band 37.5-50.2 GHz,
WRC-2000 recognized in Resolution 136 (WRC-2000) that both GSO FSS and
non-GSO FSS operators should be expected to exhibit flexibility in
achieving the appropriate balance in the sharing environment, and urged
administrations, in the application of Article **S22** to their GSO and
non-GSO FSS systems in this range prior to WRC-03, to seek balanced
sharing arrangements. Resolution 136 invites the ITU-R to undertake the
appropriate technical, operational, and regulatory studies on sharing
arrangements which achieve an appropriate balance between GSO FSS
networks and non-GSO FSS systems in the 37.5-50.2 GHz frequency range.

**PRELIMINARY VIEW (Res. 136)**:

The U.S. continues to participate in the technical, operational and
regulatory studies on sharing arrangements in order to achieve an
appropriate balance between GSO FSS, non-GSO FSS, space research, and
terrestrial systems in the frequency range 37.5-50.2 GHz.

The development of sharing criteria between GSO and non-GSO FSS systems
in the 37.5-50.2 GHz range should, notwithstanding the current
applicability of No. **S22.2**, be based on a principle of "equitable
burden sharing," to be defined by appropriate ITU-R recommendations,
between these two types of systems. Nevertheless, a
first-come/first-served regime (e.g., **S9.11A**) without appropriate
technical standards is insufficient.

(04.11.01)