Dependent Access Point can work only when having a working connectivity to an RF controller (Motorola RFS4000, RFS6000, RFS7000, NX4500, NX6500, NX9500). Dependent AP has a 3-digits numbering: AP621, AP622, AP650. When the connectivity between Dependent AP and RF controller is broken or if RF controller fails the wireless LAN service is discontinued. That's why a redundant RF controller is recommended when Dependent APs are utilized.
Independent Access Point can work without any dependency on an RF controller. Optionally, it can be managed by an RF controller. Dependent AP has 4-digits numbering: AP-6511, AP-6521, AP-6522, AP-6532, AP-7131. Independent APs are usually more expensive than Dependent APs. Independent AP are suitable for smaller WLAN deployments (without RF controller) or for installtations on remote sites in large WLAN deployments.