SPECTRUM AND FREQUENCY ISSUES

Since the beginning of the age of satellite communications with the Extraordinary World Administrative Conference in 1959 when the ITU first allocated frequencies for space telecommunications services, there has been a continuing quest for more and more spectrum for this purpose. Almost every conceivable approach to providing more spectrum has been used. Allocated bands have been expanded. New and higher frequencies have been allocated. Frequency re-use by means of spatial separation, polarization discrimination, and cellular beam patterns have been pursued, as well as closer spacing of satellites in geosynchronous orbit. Advanced modulation, encoding and multiplexing techniques and digital processing and compression have allowed increased information to flow through the same frequency bands.

Nevertheless, these techniques and more have still not satisfied the demand for more and more space services of an ever increasing broadband character. The evolution of new types of orbits for commercial satellites, (LEO, MEO, EEO (extremely elliptical orbit), inclined and polar orbits have compounded the problem in that most of the systems tend to interfere with traditional GEO systems. Future solutions currently in view include much more intensive frequency re-use through much smaller and more efficient cellular beams to achieve frequency re-uses of perhaps 50 to 100 times, allocation of more frequencies in the millimeter wave bands and perhaps rationing frequencies by auctioning them off to the highest bidder.

Further, an international study (sponsored by Europe, Japan, the United States and Canada) has been proposed to allocate "multi-purpose" digital bands so that broader ranges of spectrum can be used for many types of digital satellite services rather than just one. (In practice this is already being done on a de facto basis, but this would "legalize" this tactic to use existing bands more fully, while also developing new "mitigation" strategies to limit interference.)

The highly technical issue of frequency allocations has a number of key political issues attached to it, as follows:

Difference In Perspectives Between Developed and Developing Countries

Newcomers must be accommodated in the latest frequency allocation procedures, but there is still concern among developing countries that not enough frequencies will be available to meet their future needs. Further the needs of new LEO and MEO systems are seen as a threat to established GEO systems of developing countries and of INTELSAT. Very expensive landing rights and licensing costs for ground terminals could well be the consequence. Even going further, some developing countries would like to auction off future satellite communications spectrum to the highest bidder. Since it is difficult for satellite systems to compete with fiber optic cables, this approach could have a deadening effect on future international services via satellite.

European Perspectives on New U.S. Backed Satellite Systems

The many non-GEO systems that are planned by U.S. backed organizations are seen as unneeded in Europe (where terrestrial or GEO based systems are planned to meet forecast needs). This sets up a clash of approach between the U.S. and European administrations.

Difference in Perspectives on Millimeter Wave Frequencies: The Asia-Pacific and the United States

There is a lot of skepticism in the Asia-Pacific region, and particularly in Japan, that reliable and effective services can be provided in that region in Ka-band and above because of the very high rainfall patterns and the attendant severe attenuation at these higher frequencies. This creates a division over the feasibility of using millimeter wave frequencies on a global basis between the United States and Asia-Pacific countries. In short, there is a difference of opinion as to whether new, very broadband allocations for satellite communications should be made in these bands on a global basis.

Paper Satellites

The shortage of available frequencies and orbital slots has also given rise to filings with the ITU of so-called "paper satellites." These are filings which appear to lay claim to a particular band of spectrum and orbital slots by parties who are anticipating the filings of others for these bands and slots, in the hope that they can obtain compensation for their early filings for these resources before the actual system operators have completed time consuming domestic procedures. There are entities in Tonga, Gibraltar and elsewhere that have exploited loopholes in the ITU procedures in this way. There seems to be broad international support for new "due diligence" procedures (either administrative, financial or both) that would discourage filings by entities that do not have serious intent to deploy actual satellite systems.

Fresh Approaches for the Future

In the next five years, there will be approximately 40 meteorological satellites, 150 remote sensing satellites, and perhaps over 1000 new communications satellite systems launched (Euroconsult 1997).

The idea that future broadband services will be met by fiber optic networks and that satellites would be consigned to handle only narrow band services (i.e., the so-called "Negroponte flip") is proving wrong. The strength of satellites to provide mobility, broadcasting services, large and distributed networks and now bypass services that jump over the non-economic "last mile" suggests that tremendous additional demand for spectrum for the 21st century will only accelerate. Creative new approaches on how to meet this new demand (i.e., multi-purpose frequency allocations for digital satellites) deserve high level support and new collaborative strategic planning on an international scale.


Published: December 1998; WTEC Hyper-Librarian