What is Coverage Hole Detection

--> Coverage holes are the areas where users can't receive the signal from wireless access points.

--> If the users on the Access Point are found at low Received Signal Strength Indicator (RSSI) levels, Cisco Acess Point sends coverage hole alarm to the Cisco Wireless Controller / Prime Infrastructure.

--> Radio Resource Management Coverage Hole Detection Algorithm is used to find out Coverage holes in the wireless network.

--> Coverage holes helps us to know where to deploy one more access point in the wireless network.

--> If the users on lightweight access point are detected at threshold levels lower than Radio Resource Management Algorithm then Access Point sends coverage hole alert to the controller.

--> The alert contains the area where users are experiencing poor signal coverage in the wireless network.

--> The more number of coverage holes in the wireless network causes issues in the seamless roaming.

--> The controller uses the quality of client signal levels reported by the AP to determine if the power level of that AP needs to be increased.

--> Coverage hole detection is controller independent, so the RF group leader is not involved in those calculations.

--> The controller knows how many clients are associated with a particular AP and what the signal-to-noise ratio (SNR) values are for each client.

--> If a client SNR drops below the configured threshold value on the controller, the AP increases its power level to try to compensate for the client.

--> By default Coverage Hole Detection is enabled. You can change the settings in “Wireless -> 802.11a or 802.11b -> RRM -> Coverage” section.

--> We can enable/disable for a given WLAN as well. Under WLAN advanced settings you can see an option to enable or disable Coverage Hole Detection.