**United States of America**

**DRAFT PROPOSAL FOR THE WORK OF THE CONFERENCE**

**Agenda Item 1.24**: to review the usage of the band 13.75-14 GHz, in
accordance with Resolution **733 (WRC-2000)**, with a view to addressing
sharing conditions;

**Background Information**: At WARC-92, and as modified at WRC-95,
WRC-97 and WRC-2000, Nos. **5.502** and **5.503** were added to the
Table of Frequency Allocations to facilitate compatibility between the
existing applications of the radio services in the 13.75-14 GHz band. It
was agreed that any modifications to either of these provisions
contemplated to accommodate new technology, requirements or applications
of the FSS, must consider the overall interference environment in the
13.75-14 GHz band and be undertaken with great care in order to avoid
upsetting the delicate balance previously achieved between the services.
The constraints in the provisions are based on the planned use of the
band by gateway earth stations operating with GSO satellites in the FSS
and are intended to limit the number of FSS earth stations to the point
where sharing is possible. The present operational constraints, that
satisfy the protection criteria of current operational applications and
technology in the band 13.75-14 GHz, are found in Nos. **5.502** and
**5.503** **(WRC-2000)**.

Studies that led to the development of provisions **5.502** and
**5.503** did not account for non-geostationary-satellite orbit
fixed-satellite service systems (non-GSO FSS). With the introduction of
non-GSO FSS into this band at WRC-97, Resolution **130 (WRC-97)** was,
among other things, drafted to focus attention on the need to reexamine
the sufficiency of these provisions in maintaining the delicate balance
between the services sharing the 13.75-14 GHz band. At WRC-2000
Resolution **733** **(WRC-2000)** was developed to review the
constraints in **5.502** regarding the minimum antenna diameter of GSO
FSS earth stations, the e.i.r.p limits imposed on the radiolocation
service, and to identify possible alternative sharing situations to
those inherent to **5.502** and **5.503** in time for WRC-03.

The introduction of non-GSO FSS earth station transmitters in the band
at WRC-2000 created a potential sharing issue with the space research
service (space-to-space). Provision **5.503** was modified at WRC-2000
to include an e.i.r.p. density limit on non-GSO FSS earth stations
transmitters to accompany the limit on GSO FSS earth station
transmitters. It was understood that review of the minimum antenna
diameter limit in **5.502** called for in Resolution **733** was only in
regard to GSO FSS earth stations and not in regard to non-GSO FSS earth
stations. Only limited modifications to **5.502** and **5.503** could be
made while continuing to retain the delicate sharing balance between the
allocated services.

Studies conducted since WRC-97 and WRC-2000 have shown several salient
facts:

a)  radiolocation services are already receiving interference from
    existing FSS earth stations, despite the small number that have been
    deployed.

b)  that RR No. **5.502** maintains the delicate sharing balance between
    the radiolocation or radionavigation service and the fixed-satellite
    service only by limiting the number of FSS earth stations. In
    particular, studies have shown that sharing with radiolocation
    systems is significantly more difficult for non-GSO FSS systems than
    for GSO FSS systems, and that if requirements for the minimum
    antenna diameter of the FSS earth station were relaxed, the
    deployment of a large number of low data rate earth stations would
    collectively significantly reduce the performance of radiolocation
    and radionavigation systems, both airborne and shipborne.

c)  The feasibility of sharing between the space research service and
    the fixed-satellite service depends on limiting the number of FSS
    earth stations through RR No. **5.502** and by limiting the maximum
    power spectral density of each FSS earth station through RR No.
    **5.503**.

d)  That there is no practical means for protecting airborne
    radiolocation systems from FSS earth station emissions, and that the
    current situation is tolerable only because the number of earth
    stations is limited by the 5.502 limitations on dish diameter.

e)  ITU-R studies conducted in preparation for WRC-03, show that sharing
    between radiolocation systems and FSS earth stations with antennae
    smaller than 4.5 meters is not possible without the FSS operators
    employing mitigation techniques, and that current technology does
    not allow radar systems to mitigate interference from FSS earth
    stations. Mitigation techniques involving separation distance or
    percentage of time are neither practical nor enforceable, and no
    sharing proposals have been proposed that are enforceable by ITU
    regulations.

f)  ITU studies thus far show that separation distances of greater than
    50 km are required to protect maritime radiolocation systems from
    VSAT earth station transmissions. However, the technique of distance
    separation is not effective for protecting airborne radars or space
    science satellite systems from harmful interference by VSAT earth
    stations.

g)  Studies conducted in preparation for WRC-03 show that the maximum
    allowable power spectral densities for FSS earth station antennae
    smaller than 4.5 meters, needed to ensure protection of space
    research operations, will not allow practical FSS VSAT
    implementations.

The concept of a separation distance to mitigate interference and
promote sharing has been directed at using FSS earth station e.i.r.p.
reductions and placing the VSAT terminals a specified distance inland
from the coast. The reverse of this would be to restrict the radars a
certain distance out to sea from the coast, or some combination of these
approaches. Locating VSAT terminals well inland from coastlines would be
the only solution that would allow maritime radiolocation systems to
maintain operations close to shore. However, the enforceability of this
approach is very questionable given the market needs to have VSATs
placed without restrictions and noting that many population centers are
located close to coasts. Requiring maritime radar systems to remain a
significant distance from shore would impose severe restrictions on the
ability of their host platforms to protect themselves during essential
and routine operations. Therefore, the application of separation
distance as a mitigation technique to protect shipborne radars against
interference from VSAT earth stations is not feasible and thus it cannot
be supported. Furthermore, such an approach would have no affect on
protecting airborne radiolocation systems, or space science platforms.

**Proposal**:

##### USA/ /1 SUP

**Resolution 733 (WRC-2000)**

**Reasons**: Studies completed in accordance with agenda item 1.24 and
Resolution **733** have not determined an effective method of preventing
FSS systems operating with earth stations with antennae smaller than 4.5
meters from creating harmful interference to other services in the
13.75-14.0 GHz band. Therefore Resolution **733 (WRC-2000)** no longer
applies to **5.502** and can be suppressed.

## USA/ /2 (MOD)

**5.502**: In the band 13.75-14 GHz, an earth station in the
fixed-satellite service shall have a minimum antenna diameter of 4.5 m
and the e.i.r.p. of any emission should be at least 68 dBW and should
not exceed 85 dBW. In addition the e.i.r.p., averaged over one second,
radiated by a station in the radiolocation or radionavigation services
shall not exceed 59 dBW. The protection of assignments to receiving
space stations in the fixed-satellite service operating with earth
stations that, individually, have an e.i.r.p. of less than 68 dBW shall
not impose constraints on the operation of the radiolocation and
radionavigation stations operating in accordance with the Radio
Regulations. No. **5.43A** does not apply. ~~See Resolution **733
(WRC-2000)**.~~

**Reasons**: Consequential, we propose *No Change*
(**[NOC]{.underline})** to the text contained in **5.502** other than
the removal of the reference to Resolution **733**.

**USA/ /3 [NOC]{.underline}**

**5.503**

**Reasons**: Provisions **5.502** and **5.503** are integrally related
in maintaining the delicate sharing balance between the radiolocation,
radionavigation, space research and fixed-satellite services in the
13.75-14 GHz band. Maintaining these provisions in their current form
will ensure that all services can continue to share the band in a
compatible manner.