Description: The mode uses to set the guard interval which is the necessary interval to receive and dispatch wireless signal to make the communication well. Normal means it sets the normal guard interval, short means it sets the short guard interval. The default guard interval mode is normal mode. The normal guard interval is 800 ns, and the short guard interval is 400 ns. If it's is not a kind of 11n or mixed with 11n AP, you can't config the it's hwRadio80211nGuardIntervalMode value. When the AP changed to be other kinds, the value of hwRadio80211nGuardIntervalMode will change to be default value.