What do you mean by the state of WiFi?
Do you want to identify, when the interface itself is enabled?
Do you want to monitor, when there ae users connected via the WiFi?
Or do you want the router to be used as a client to another access point and monitor data connection health?
In any case, your go to option would be by a combination of I/O juggler and a custom script. As a reference please check this other thread.