Satellite interference is a costly problem for operators around the world. Interference comes from many sources although the majority are human error and accidental. In the last year, however, there has been a growing controversy over the deployment of broadband wireless access (BWA) services such as WiMAX and International Mobile Telecommunications (IMT) systems and the potentially devastating outcome on the C-band frequency.

The C-band frequency is used by fixed satellite services (FSS) operators around the world to deliver vital communications services and is critical to countries in the Equator region where extensive rain fade makes the use of Ku-band impractical. There are approximately 160 geostationary satellites currently operating in the C-band frequency and it is estimated that two out of every three commercial satellites currently under construction will likely utilize the C-band frequency.

An extensive hardware deployment representing billions of dollars worth of investment by satellite operators and users is in place today in support of FSS communications in C-band. Contrary to terrestrial systems that can be modified post deployment to accommodate changes, satellites, once in orbit, cannot be altered.

The Problem of Spectrum Sharing As deployment of BWA services gain momentum in several countries, the satellite industry has had to combat an increase in reported interference incidents where fixed and mobile satellite services are being severely disrupted by interference from terrestrial wireless services. These incidents have, at times, brought TV-signal feeds down completely as was the case in Hong Kong when an estimated 300,000 households throughout Asia lost signal due to a BWA field trial. Another test in Bolivia during the start of World Cup soccer impacted about 30 percent of households receiving World Cup coverage via satellite.

BWA equipment will operate within the 3.4-3.7 GHz ranges of the FSS extended C-band frequency. This presents problems for satellite systems with overlapping bands that are susceptible to out-of-band emissions and LNA/LNB saturation. Industry analyses and early tests of potential BWA interference have all pointed to the potential for significant threat to satellite services in the C-band.

The possibility that portions of the C-band spectrum would be allocated for IMT systems is also causing concern on the regulatory environment. Satellite operators, fearful that spectrum will become unavailable during the lifetime of a new satellite, thus leaving the operator unable to successfully market new or even replacement inventory, may reconsider future investments.

What is Being Done The satellite industry is committed to defining the impact of sharing the C-band frequencies and identifying if – and how – fixed satellite services and wireless services can co-exist. Organizations such as the Asia-Pacific Broadcasting Union, the Asia Pacific Satellite communications Council, Asia-Pacific Telecommunity, Global VSAT Forum, Satellite Users Interference Reduction Group (SUIRG) and a consortium of prominent satellite operators have all submitted papers and studies on this topic.

Earlier this year for example, SUIRG and eight other trade associations representing over 400 satellite companies worldwide with a combined revenue in excess of €66 billion, sent a letter to the EC Commissioners urging them to oppose the preliminary European proposal to the International Telecommunication Union (ITU) World Radiocommunication Conference (WRC) 2007 to open any part of the C-band for terrestrial mobile technologies. Thanks to the overwhelming demonstrations of support from national administrations, the communications user community and the global satellite industry, WRC decided to restrict IMT, including WiMAX, from any part of the satellite C-band.

Robert W. Ames. Jr.
President
Satellite Users Interference Reduction Group