***RCS WRC --07 Agenda Item Scope and High-Level Work Plan***[^1]

**Agenda Item 1.8 (Res 122)**: "to consider the results of ITU-R studies
on technical sharing and regulatory provisions for the application of
high altitude platform stations operating in the bands 27.5-28.35 GHz
and 31-31.3 GHz in response to Resolution **145 (WRC-03)**, and for high
altitude platform stations operating in the bands 47.2-47.5 GHz and
47.9-48.2 GHz, in accordance with Resolution **122** **(Rev. WRC‑03);**

**Short Description**: Resolution **122 (WRC-03)**, contains the
following issues:

1.  To study, as a matter of urgency, power limitations applicable for
    HAPS ground stations to facilitate sharing with space stations
    receivers.

2.  To review refinements to the regulatory provisions that might be
    needed in order to address those cases where the deployment of HAPS
    in the territory of one administration may affect other
    administrations.

3.  Continue to carry on studies to determine the appropriate technical
    sharing criteria, considering the operational environments and
    requirements of the Fixed, MSS, FSS, and RAS services.

**Background**:

WRC-97 made a provision for the operation of High Altitude Platform
Stations (HAPS), also known as strategic repeaters, within a 2 X 300 MHz
portion of the fixed-service allocation in the bands 47.2-47.5 GHz and
47.9-48.2 GHz. During WRC-00, several countries expressed a need for a
lower frequency band for HAPS due to excessive rain attenuation that
occurs at 47 GHz.

In the WRC-03 revision to Resolution 122, the ITU-R was requested to
complete sharing studies between the FSS and HAPS operation in the fixed
service. Following WRC-2000, Recommendation ITU-R SF.1481 was developed
and adopted. This recommendation makes clear that co-frequency operation
between HAPS in the fixed service and FSS networks and systems is
feasible in the 47.2 -- 47.5 GHz and 47.9 -- 48.2 GHz band (even though
it was noted that "there may be a need to develop the maximum allowable
power flux-density at satellites on the GSO due to aggregate
interference caused by ground user terminals of high altitude platform
networks").

In the revision to Resolution 122 approved at WRC-03, co-existence
between HAPS in the FS and the FSS at 47.2 -- 47.5 GHz and 47.9 -- 48.2
GHz was presumed feasible, as administrations were encouraged to
facilitate inter-service coordination. The ITU-R was invited to study
power limitations on HAPS ground stations to facilitate sharing with
space station receivers, regulatory criteria between HAPS in the FS and
both radio astronomy and FSS systems (taking into account operational
environments and the requirements of FSS systems). WRC-03 decided, after
much debate, to retain the prior limitation on notices for new FSS
networks -- but only in Regions 1 and 3. WRC-03 also decided to maintain
indefinitely notices for HAPS that were received by the BR prior to 22
November 1997.

**Countries with a particular interest:** Japan

**Scope of Agenda Item**: The responsible group for this agenda item is
WP 4-9S, with WP 9B and 9D as contributing groups, and WP
4A(orbit/spectrum utilization), as an interested group.

**Key technical/regulatory issues to be resolved**:

-   Appropriate power limits that permit HAPS ground station operation
    while protecting space borne receivers.

-   Refinement of regulatory provisions applicable to HAPS stations in
    the fixed service in these bands.

**Key policy issues to be resolved**:

-   Possible sharing and continued protection of incumbent services.

-   Coordination procedures between systems in the fixed service and
    systems of the co-primary satellite service in the same bands
    (47.2-47.5 GHz and 47.9-48.2 GHz)

**Work Plan and Organization Participation**:

Work to be completed in support of this agenda item is as follows:

1.  Determine future HAPS operational and technical requirements.
    (Government and Industry)

2.  Determine acceptable power limitations that provide protection for
    incumbent satellite services. (Government and Industry)

3.  Perform appropriate sharing studies. (Government and Industry)

4.  Develop Draft CPM text. (Government and Industry)

5.  The responsible group for this agenda item is WP 4-9S while WP 9B
    and 9D are Contributing groups and WP 4A is an interested group.

**Reference Material**:

ITU-R Recommendation **F.1500**, ITU-R Recommendation **SF.1481**,
WRC-03 Resolution **122**, RR No. **5.552**

[^1]: **Author**: G. Chinault (DoD) and Lily Assefa (DoD) **Document
    Date**: June 1, 2004