specifies the operating channel of the system, within the 100 MHz available in the 5.8GHz UNII band. To avoid interference, two PTP links operating in the same physical location (co-located) or within close proximity (e.g. across the street) must be separated by at least one channel, i.e. the gap between channels should be 20 MHz or more (e.g. channels 1 and 3).