Coverage

In telecom, the coverage of a base station is represented by the geographical area where the station can communicate.

Factors
Coverage depends on: the antenna type, the amplifier power levels, the radio propagation and the receiver sensitivity. To be more precise, the coverage level is influenced by: the terrain type, buildings, technology, radio frequency and perhaps most importantly for two-way telecommunications the sensitivity and transmit efficiency of the consumer equipment. Some frequencies provide better regional coverage, while other frequencies penetrate better through obstacles, such as buildings in cities.



Important Note: Coverage is highly dependent on the mobile station's ability to "see" the antenna, as well as on the antenna's ability to reach the mobile station.

The ability of a mobile phone to connect to a base station depends on the strength of the signal. The signal can be boosted by higher power transmissions, more efficient antennas, taller antenna masts etc.

Coverage also depends on the choice of antenna type, be it omni or sector. Some of the factors influencing this choice are the location of the base station, the terrain, the environment etc.

Radio horizon is a factor that needs to be taken into account when determining the coverage, as it refers to a locus of points at the surface of the Earth where the signal of a transmitting antenna is tangential to its surface. The radio horizon is the farthest point of propagation of a transmitting antenna and is illustrated in the image below.



Coverage Estimation
To measure the coverage, network planners use simple propagation models to roughly calculate what can be expected in a specific environment (such as Hata, COST231 or Walfisch-Ikegami propagation models), or they use more accurate tools that take into account the exact type of environment where the network is to be deployed, as the Radio Mobile RF propagation simulation software.

Coverage Maps
Coverage maps to indicate to users the station’s intended service area. The maps may also separately denote supplementary service areas where good reception may be obtained but other stations may be stronger, or where reception may variable but the service may still be usable. Often coverage maps show general coverage for large regions and therefore any boundary indicated should not be interpreted as a rigid limit.

The biggest cause of uncertainty for a coverage map is the quality (mainly sensitivity) of receiving apparatus used. A coverage map may be produced to indicate the area in which a certain signal strength is delivered. Even if it is 100% accurate (which it never is), a major factor on whether a signal is receivable depends very much on whether the receiving apparatus is sensitive enough to use a signal of that level.