The struggle to preserve satellite communications using radio frequencies around 4 gigahertz is heating up.

Because the satellite industry uses this C-band frequency around the world, in mid-February, an alliance of leading satellite associations issued an information paper on the perceived threat arising from the rollout of mobile broadband technologies, showing technologies in the same spectrum. This major industry effort shows that the battle lines are shaping up for controversy on this matter at the ITU’s World Radiocommunication Conference (WRC-07), which is scheduled to begin in late October in Geneva.

WRC-07 Agenda item 1.4. deals with identification of future spectrum for development of wireless services, generically known as international mobile telecommunications (IMT). We noted in our roundup of issues for 2007 that this is going to be one of the hot topics this year.

Bearing out these predictions, the world’s satellite associations are making their position clear that the WRC-07 agenda item should not be an excuse to move terrestrial mobile broadband technologies into spectrum already heavily used by satellite links. The European Satellite Operators Association joined with the European Satellite Action Plan Regulatory Group, Asia-Pacific Satellites Communications Council, Satellite Industry Association and the Global VSAT Forum to outline what they view as an “unprecedented threat” to the provision of satellite services.

The satellite associations point out that operators use C-band to provide essential services such as TV transmissions, distance learning, telemedicine and disaster recovery, and in some countries C-band spectrum serves as the core communications network. These particular frequencies are especially useful due to their low susceptibility to rainfall interruptions and their superior propagation characteristics, according to the paper.

The associations argue that about 160 geostationary satellites already operate in this band and nearly two out of three commercial satellites being manufactured will use this spectrum. These facilities under construction represent capacity, by the associations’ calculation, of more than 3,000 transponders. Moreover, communications satellites using other frequencies still depend on the C-band for tracking, telemetry and control links.

Attached to the satellite associations’ information paper are maps showing deployment of earth stations using C-band spectrum for just one major operator. Africa and large parts of South America are literally blanketed with sites, with significant concentrations in Europe and parts of Asia.

Another map identifies registered C-band earth stations in Europe and the 100-kilometer exclusion zone that would be the minimal area around each station for protecting their operation against harmful interference from terrestrial operators. This map supports the point that large areas of Europe would not be usable for terrestrial C-band IMT deployment. The satellite associations argue that any deployment of mobile terrestrial IMT in this band would be irresponsible since those mobile services are by definition supposed to be usable everywhere.

The satellite associations targeted their information paper at the Conference Preparatory Group Meeting (CPM) that met in Geneva in late February to early March. This very intensive two week meeting produced a draft CPM report that the WRC-07 will use as a resource to support its ultimate decisions.

Satellite representatives emphasized the same arguments at a workshop on WRC-07 that the European Commission held in Brussels on March 9.

The satellite associations conclude in their information paper that satellite operators would be “severely affected at [the] global level” by any moves adopted at the ITU to permit deployment of mobile terrestrial broadband services in the C-band. They stress that important satellite services in regions such as Africa, Asia and Latin America would be particularly threatened, and they invite the international community to maintain the current ITU allocation status for C-band satellite services.

The CPM draft report did not reach a definitive conclusion on these issues, instead noting that the C-band may yet be considered as a candidate band for terrestrial IMT services, but also identifying the importance of the band for satellite applications. Because the CPM results do not settle the arguments, these positions will be debated through the rest of this year. For the satellite industry, the struggle for C-band is not over.