**UNITED STATES**

**PRELIMINARY VIEWS ON WRC-07**

**WRC-07 Agenda Item 1.8:** 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 response to Resolution **122 (Rev.WRC‑03)**;

**ISSUE:**

**Resolution 122:** Matters related to the use of the bands 47.2-47.5
GHz and 47.9-48.2 GHz by high altitude platform stations (HAPS) in the
fixed service and by systems and networks in the fixed-satellite service
(FSS).

**Resolution 145:** The feasibility, subject to the conditions in
*resolves 2* and *3* of Resolution 145, of identifying a suitable and
preferably a common 300 MHz segment of the band 27.5-28.35 GHz paired
with the 300 MHz band at 31-31.3 GHz, for use by HAPS in the countries
listed in Nos. **5.537A** and **5.543A** or countries in Region 2
planning provisional operation, taking into account the requirements of
other fixed-service systems and other services.

**BACKGROUND**:

**Resolution 122:** The ITU has been considering the implications of
HAPS in the fixed service in the 47.2-47.5 GHz and 47.9-48.2 GHz band
since 1997, when WRC-97 first made provision for the operation of HAPS
within the fixed service. Studies have been ongoing under versions of
Resolution 122 since WRC-97.

In the WRC-2000 revision to Resolution 122, the ITU-R was requested to
complete sharing studies between the FSS and HAPS operations in the
fixed service. Following WRC-2000, Recommendation ITU-R SF.1481 was
developed and adopted. This recommendation makes clear that co-frequency
operations 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 bands (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
interservice coordination. The ITU-R was invited to study power
limitations on HAPS ground stations to facilitate sharing with space
station receivers, regulatory provisions to address deployment of HAPS
in the FS near country borders, and technical sharing criteria between
HAPS in the FS and both radio astronomy and FSS systems (taking into
account the 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.

**Resolution 145:** WRC-2000 decided to adopt provisions for the
operation of HAPS on a non-interfering/non-protected basis in the bands
27.5-28.35 and 31-31.3 GHz in Region 3, but did not allow operation in
the entire bands until studies could be completed to determine how best
to protect existing services in these and nearby frequency bands.

WRC-03 further refined these provisions by deciding to limit HAPS
operation to 300 MHz in a specified direction in each of these two
bands, retaining the requirement for HAPS to operate on a
non-interfering/non-protected basis in these 300 MHz segments, and
adopting Resolution **145**, which created the possibility of allowing
Region 2 administrations to advise the Radiocommunications Bureau of
their intent to implement HAPS systems within the bands 27.5-28.35 and
31-31.3 GHz. Administrations intending to implement HAPS in these bands
are to seek the explicit agreement of concerned administrations in
accordance with *resolves* 4 of this Resolution.

Under Resolution 145 (WRC-03), the use of HAPS within the fixed-service
allocations within the 27.5-28.35 GHz and 31-31.3 GHz bands must be
limited, pending the completion of the feasibility studies, to 300 MHz
in each band, and is subject to the condition that such use must not
cause harmful interference to, nor claim protection from, other stations
of services operating in accordance with the Table of Frequency
Allocations of Article **5**. Furthermore, the resolution specifies that
that the development of these other services shall proceed without
constraints by HAPS operating pursuant to the resolution. With respect
to the band 31-31.3 GHz, Resolution 145 specifies that systems using
HAPS in the band 31-31.3 GHz must not cause harmful interference to the
radio astronomy service having a primary allocation in the band
31.3-31.8 GHz, taking into account the protection criterion given in
Recommendation ITU‑R RA.769. The resolution contains limits on the level
of unwanted power density into the HAPS ground station antenna in the
band 31.3-31.8 GHz in order to ensure the protection of satellite
passive services.

**U.S. VIEWS:**

**[Resolution 122 (Rev. WRC-03)]{.underline}**

1\. The U.S. believes, as it did at WRC-03, that the question of the
feasibility of co-frequency operation between HAPS in the FS and the FSS
at 47.2-47.5 GHz and 47.9-48.2 GHz has been answered in the affirmative.
With that, there no longer is any need for Resolution 122, the
restrictions it imposes on FSS notices in Regions 1 and 3, or on the
extraordinary freedom from implementation deadlines it extends to FS
HAPS notices in the 47.2-47.5 GHz and 47.9-48.2 GHz bands. Thus,
Resolution 122 should be suppressed.

2\. The U.S. will participate in studies on the power limitations to be
applied to HAPS ground stations to protect space station receivers in
the 47.2-47.5 GHz and 47.9-48.2 GHz bands.

**[Resolution 145 (WRC-03)]{.underline}**

1\. HAPS use of the 31-31.3 GHz allocation must ensure protection from
interference to the passive services operating in 31.3-31.8 GHz

2\. The existing HAPS ground station power density limits described in
No. 5.543A adequately protect passive satellite services operating in
31.3-31.8 GHz, yet provide sufficient power for operation of
ground-to-HAPS links. The United States anticipates supporting no change
to the existing No. 5.543A. The U.S. will participate in studies on the
power limitations to be applied to HAPS ground stations to protect space
station receivers.

3\. The United States also supports the continued studies called for in
Resolution **145 (WRC-03)** that will demonstrate whether HAPS can
operate successfully on a non-interference/non-protected basis in the 28
GHz and 31 GHz bands, and the inclusion of the results of these studies,
as appropriate, in ITU-R Recommendations. However, recognizing the
regulatory status of this service in these bands, the United States does
not support the specification of interference or sharing criteria for
HAPS in ITU Radio Regulations for these bands. (June 2004)