coverage

In mobile and radio engineering, coverage means the geographic area where a transmitter's signal is strong enough to be received and used. This is measured not in ideal conditions but in real terrain: through buildings, across hills, and around obstacles. A cell tower nominally covers some radius around itself, but actual coverage is jagged and uneven. The boundary is not a clean circle on a map.

Coverage strength is quantified in decibels relative to a milliwatt (dBm). For a mobile phone to maintain a voice call, signal must typically exceed around -95 to -100 dBm depending on the standard and conditions. Data services demand stronger signals, often -85 dBm or better. Below these thresholds, the link drops or becomes unreliable. Operators measure coverage by driving routes with test equipment, logging signal levels, and building heat maps that show where service is adequate, marginal, or absent.

Mobile networks use overlapping cells to create continuous coverage across a region. Each cell site broadcasts on specific frequencies (850 MHz, 1900 MHz, 2100 MHz, and higher bands in modern systems). A phone selects the strongest available signal and hands off between towers as the user moves. Coverage gaps emerge in valleys, tunnels, dense urban canyons, and remote areas. Indoor coverage is notably weaker; concrete and metal studs attenuate signals severely, which is why in-building systems and femtocells are deployed in some commercial and residential spaces.

Coverage and capacity are distinct. A tower may have good signal reach (coverage) but insufficient bandwidth to serve many simultaneous users (capacity). Operators often deploy additional carriers on the same frequency, add new frequency bands, or install more tower sites to address capacity shortfalls. Coverage is about whether you have any signal; capacity is about whether that signal can handle your traffic.

The term is also used in satellite communications, where coverage refers to the footprint of a satellite's antenna. A geostationary satellite might cover a continent or an ocean basin; low-earth orbit satellites provide regional coverage and require constellation management to maintain global service. In terrestrial broadcasting, coverage describes the area receiving an adequate signal from a transmitter, and regulations in many countries specify minimum coverage obligations for operators holding spectrum licenses.