Radio Interference with Satellite-Based Services

Terrestrial wireless service providers are lobbying for more spectrum to meet the demand for mobile data. The Federal Communications Commission (FCC) is considering proposals to share L-band spectrum in or near bands currently used by weather satellites, the Global Positioning System (GPS), and aircraft navigation systems. Powerful terrestrial signals in these frequency bands could interfere with receivers designed to track the relatively weak signals transmitted by navigation and meteorology satellites. The authors suggest that the FCC could undertake spectrum sharing or reallocation studies that not only take into account the near-term profits of spectrum license holders, but also consider:

• The societal benefits of—and public-sector dependence upon—this spectrum
• The economic benefits of existing satellite-based services
• The technical feasibility of mitigating terrestrial interference
• The time and costs to develop, test, manufacture, and install technical mitigations for spectrum sharing
• The vested interests, sunk costs, and innovation already invested in existing systems

Considerations should include the technical differences between radio and wireless applications, the value of precedence in regulatory matters, and the consequences of abrupt changes to traditional spectrum allocations that contradict decades of careful planning. Regulatory decisions should also consider the unique physics of space-based services compared to terrestrial radio services, including potentially large differences in received signal power.

Author: Tom Powell, David Lubar, Karen Jones