The network coverage design involves planning of the network coverage areas and signal strength within the coverage areas. This section first describes the concept of the wireless network coverage area, and then introduces the coverage radius and coverage distance that measure a wireless coverage area.

Coverage Area

An AP transmits radio signals through an antenna and generates a wireless network coverage area around the antenna. The signal strength becomes weaker as radio signals are transmitted further. Generally, the area where the signal strength around an antenna is greater than the edge field strength is called wireless network coverage area, as shown in Figure 1. The field strength of radio signals at the edge of a network coverage area is called edge field strength. For example, if the signal strength indicator value in a common coverage area is -65 dBm, the edge field strength must be greater than or equal to -65 dBm.

Figure 1 Network coverage area from the top view (omnidirectional antenna)

Coverage Radius

The coverage area of omnidirectional antennas is measured by coverage radius. An AP with an omnidirectional antenna installed on a ceiling is used as an example, as shown in Figure 2. The AP's installation height is determined according to the site survey. The maximum transmission distance of radio signals can be calculated based on the edge field strength. After the installation height and maximum transmission distance are determined, the coverage radius of the antenna can be calculated, thereby the effective coverage area of radio signals can be obtained.

Figure 2 Coverage radius

Coverage Distance

The coverage area of a directional antenna is measured by coverage distance. An AP with a directional antenna installed against a pole outdoors is used as an example, as shown in Figure 3. The maximum transmission distance from the antenna to the coverage area edge can be calculated using a formula. The antenna height can be obtained according to the site survey.

Figure 3 Coverage distance

Figure 4 Network coverage area from the top view (directional antenna)

As shown in the preceding figures, the coverage radius and coverage distance can be calculated when the maximum transmission distance is determined. To calculate the maximum transmission distance, the radio transmit power and signal strength are required. The following section will describe the concepts of power and signal strength.

More information, please refer to:

WLAN Network Planning Guide