| 摘要 |
Geographic reuse of frequencies within a multisite communication system is dynamically altered as a function of communication unit type. For example, a portable communication unit generally has a relatively small effective coverage area (101) due to its low power and unfavorable antenna structure. A vehicle-mounted communication unit usually employs higher power and a more-efficient, vehicle-mounted antenna structure, thus giving the vehicle-mounted unit a larger effective coverage area (102). Communication units installed in aircraft enjoy a still wider coverage area (103), primarily because of the antenna's superior height above terrain. Since some communication unit types pose a smaller risk of interference, increased geographic reuse can be tolerated. Similarly, reuse can be diminished to accommodate communication unit types that pose a significant risk of interference over a wide geographic area. |
