Initial Opposition Forms Against WRC-12 Satellite Allocations

GENEVA -- Difficult sharing studies have prompted several administrations to oppose some or all of the proposed bands under a WRC-12 agenda item on possible new mobile satellite service (MSS) allocations to spur advanced wireless communications, according to early proposals. Some regional groups, notably the Americas, Europe and the Asia-Pacific regions, and certain administrations are expected to introduce proposals that may contain support.

Inmarsat and Luxembourg want an ITU-R group on space services this month to consider for approval the draft text in a proposed new report on sharing studies in frequency bands relating to geostationary orbit MSS systems, they said in submissions. The report relates to the WRC-12 agenda item on allocations for MSS. The submissions will be considered at a meeting starting Wednesday. Sharing with non-geostationary MSS systems was not studied, the draft report said.

An ITU-R report shows a shortfall of spectrum available for the satellite component of international mobile telecom (IMT), the international standard for advanced wireless communications, in the space-to Earth direction of between 144 and 257 MHz for the year 2020, a document said. It also indicates a shortfall in the Earth-to-space direction of between 19 and 90 MHz for the year 2020.

Discussions in ITU-R on sharing in a number of bands have been difficult, while some bands were eliminated early in the process. Work under the agenda item is focusing on the 4-16 GHz range. Sharing studies have focused on 5150-5250 (downlink), 7055-7250 (downlink), 8400-8500 MHz (uplink), 10.5-10.6 (downlink), 13.25-13.4 (downlink), and 15.43-15.63 GHz (uplink).

A complicated variety of sharing concerns, including from interests in the aeronautical, maritime, terrestrial and scientific services, have been raised in documents and meetings. The U.S. WRC-12 position calls for no change to the frequency bands, thus no new allocations. ITU-R studies of some of the possible bands indicate difficulties in sharing with existing services, the U.S. position said. ITU-R didn’t study other possible bands, it said. The U.S. proposal advocates no change because of results of ITU-R sharing studies, it said. The European group hasn’t submitted a position. Strong concerns over sharing have also been raised in European meetings.

Administrations in the Regional Commonwealth in the Field of Communications (RCC) “object to” allocation of the bands 7055-7250 MHz (space-to-Earth), 8400-8500 MHz (Earth-to-space), 10.5-10.6 GHz (space-to-Earth) for MSS, a WRC-12 proposal said. The regional group of administrations is made up mostly of former countries of the ex-Soviet Union. The RCC doesn’t support allocation of the bands 13.25-13.4 GHz (space-to-Earth) and 15.43-15.63 GHz (Earth-to-space) for MSS, it said. One MSS executive was hopeful studies would convince Russia that sharing in the 15 GHz band would work (CD Jan 27 p11).

The Scientific Committee on Frequency Allocations for Radio Astronomy and Space Science (IUCAF), in a submission to the ITU-R working party, said studies of compatibility between radio astronomy service (RAS) operations in the band 15.35-15.4 GHz and MSS operations at 15.43-15.63 GHz are immature but provide little indication that compatibility can be achieved. The comments were in response to possible changes this month to the draft new ITU-R report on the feasibility of MSS operations in some frequencies bands. Updated studies say ground-based mobile earth stations would not interfere into RAS stations, Luxembourg said in a submission in response. Luxembourg also questioned the protection criteria for the band 15.43-15.63 GHz provided by an ITU-R group dealing with certain terrestrial services and needed for the aeronautical radio navigation service (ARNS).

Inmarsat said an analysis of interference from aircraft-mounted MSS uplinks into RAS systems in the 15.35-15.4 GHz band showed that the recommended interference threshold into the RAS station can be met if a proper filter is applied to the MSS user terminal. The band is allocated on a primary worldwide basis to the radio astronomy passive space research on a primary basis and is adjacent to the 15.43-15.63 GHz band being considered for a MSS allocation under a WRC-12 agenda item. The interference threshold can be maintained using available technologies, Inmarsat said. A minimum guard band of 30 MHz would exist between the MSS emissions and the RAS band, it said.

Russia said an analysis of the results of the sharing studies allows a final conclusion to be drawn: Co-frequency and co-coverage operation of ARNS, including aircraft landing systems, and MSS in the band 15.43-15.63 GHz isn’t feasible. The required separation distance is up to 500 km, it said. So no global MSS allocation in 15.43-15.63 GHz can be made, Russia said. Sharing between MSS (downlink) and ARNS systems, including sense and avoid navigation aid radars, isn’t feasible in the frequency band 13.25-13.4 GHz, Russia said. For the MSS to obtain an allocation in the 13.25-13.4 GHz band, it must ensure protection of the existing and future ARNS systems from harmful interference, the U.S. said in a submission. It’s necessary for the proposed MSS downlink to operate with a power flux density that will not exceed a level of -137 dBW/m2/1 MHz at the aircraft radionavigation radar antenna, it said.

If a new allocation is made for the proposed MSS downlink under the WRC-12 agenda item 1.25, then a caveat that the MSS downlink operations will not cause harmful interference to or constrain use and development of ARNS must be included in the Radio Regulations, the U.S. said. A recently approved ITU-R report related to a separate WRC-12 agenda item, on allocations for control of unmanned aerial systems (UAS) in unsegregated airspace, points to the 13.25-13.4 GHz band for UAS sense and avoid radionavigation radars, the U.S. said.